Canadian Science Advisory Secretariat (CSAS) 

Research Document 2022/038 
Quebec Region 

June 2022  

Assessment of the Arctic surfclam (Mactromeris polynyma) stocks of Quebec 
coastal waters in 2020 

Rénald Belley and Anne-Sara Sean 

Fisheries and Oceans Canada 
Institute Maurice-Lamontagne 

850, route de la Mer 
Mont-Joli, Québec G5H 3Z4



 

 

Foreword 
This series documents the scientific basis for the evaluation of aquatic resources and 
ecosystems in Canada. As such, it addresses the issues of the day in the time frames required 
and the documents it contains are not intended as definitive statements on the subjects 
addressed but rather as progress reports on ongoing investigations. 

Published by: 
Fisheries and Oceans Canada  

Canadian Science Advisory Secretariat  
200 Kent Street 

Ottawa ON K1A 0E6 
http://www.dfo-mpo.gc.ca/csas-sccs/  

csas-sccs@dfo-mpo.gc.ca 

 
 

© Her Majesty the Queen in Right of Canada, 2022 
ISSN 1919-5044 

ISBN 978-0-660-44107-8 Cat. No. Fs70-5/2022-038E-PDF 
Correct citation for this publication:  
Belley, R. and Sean, A.-S. 2022. Assessment of the Arctic surfclam (Mactromeris polynyma) 

stocks of Quebec coastal waters in 2020. DFO Can. Sci. Advis. Sec. Res. Doc. 2022/038. 
viii + 74 p. 

Aussi disponible en français : 
Belley, R. et Sean, A.-S. 2022. Évaluation des stocks de mactre de Stimpson (Mactromeris 

polynyma) des eaux côtières du Québec en 2020. Secr. can. des avis sci. du MPO. Doc. de 
rech. 2022/038. ix + 75 p. 

http://www.dfo-mpo.gc.ca/csas-sccs/
mailto:csas-sccs@dfo-mpo.gc.ca


iii 

TABLE OF CONTENTS 
ABSTRACT ................................................................................................................................ viii 
INTRODUCTION .......................................................................................................................... 1 

ARCTIC SURFCLAM DISTRIBUTION AND BIOLOGY ................................................................ 1 
DISTRIBUTION ........................................................................................................................ 1 
GROWTH ................................................................................................................................. 2 
REPRODUCTION .................................................................................................................... 2 

DESCRIPTION OF THE FISHERY ............................................................................................... 3 
FISHERY MANAGEMENT ....................................................................................................... 3 
CONSERVATION APPROACH ............................................................................................... 3 

DATA SOURCE AND ANALYSES ............................................................................................... 4 
COMMERCIAL FISHERY DATA .............................................................................................. 4 

Landings ................................................................................................................................ 5 
Fishing effort ......................................................................................................................... 5 
Catch per unit effort ............................................................................................................... 6 
Exploitation rate indicator ...................................................................................................... 6 

COMMERCIAL SAMPLING ..................................................................................................... 7 
RESEARCH SURVEYS ........................................................................................................... 7 

ASSESSMENT OF THE RESOURCE STATUS ........................................................................... 8 
REVIEW OF INDICATORS ...................................................................................................... 8 

Decision rules ........................................................................................................................ 9 
ECOSYSTEM CONSIDERATIONS ......................................................................................... 9 

Habitat ................................................................................................................................. 10 
Species present .................................................................................................................. 10 

CONCLUSION ............................................................................................................................ 11 

REFERENCES CITED ................................................................................................................ 12 

TABLES ...................................................................................................................................... 15 

FIGURES .................................................................................................................................... 28 



 

iv 

LIST OF TABLES 
Table 1. Parameters of the von Bertalanffy growth curve estimated from growth rings on 

the shells of Arctic surfclams from some eastern Canadian beds. ......................... 15 
Table 2. Management measures for the Arctic surfclam commercial fishery in 2020. ... 15 
Table 3. Number of Arctic surfclam samples collected from 2018 to 2020 in the DFO 

commercial dockside sampling program and sampling protocol by fishing area. ... 16 
Table 4. Arctic surfclam landings (t live weight) by region and year. ............................. 17 
Table 5. Arctic surfclam landings (t live weight) by fishing area group and year. .......... 18 
Table 6. Total Allowable Catch (TAC, t live weight) of Arctic surfclams since the 

beginning of the fishery in 1993 by fishing area and year. ..................................... 19 
Table 7. Arctic surfclam fishing effort (in days) by fishing area and year....................... 20 
Table 8. Effort in area dredged (km2) in the Arctic surfclam commercial fishery by fishing 

area and year. ........................................................................................................ 21 
Table 9. Catches per unit of effort (kg per tow for a 1-m-wide dredge) estimated using 

logbook data, by fishing area of the Arctic surfclam commercial fishery by fishing 
area and year. ........................................................................................................ 22 

Table 10. Area of the beds, number of daily fishing positions available and retained for 
the beds, and areas estimated through the Kernel analysis corresponding to 100% 
and 95% of the fishing effort, by fishing area and bed. .......................................... 23 

Table 11. Known area of the beds, area corresponding to 95% of the fishing intensity, 
total and mean fishing effort (area dredged) and mean exploitation rate by bed and 
fishing area. ........................................................................................................... 24 

Table 12. Annual mean size (mm) at landing of Arctic surfclams, by fishing area and 
year, estimated by a model that takes into account the year and bed. ................... 26 

Table 13. Indicators used in the decision rule to increase the TAC. Indicators in bold 
mean that they meet the conditions for a quota increase. ...................................... 27 

  



 

v 

LIST OF FIGURES 
Figure 1. Mactromeris polynyma (English name: Arctic surfclam, Stimpson’s surfclam; 

French name: mactre de Stimpson) (Bourdages and Goudreau 2012). ................. 28 
Figure 2. Known distribution of Arctic surfclams in Quebec inshore waters based on 

data collected from logbooks, research surveys and exploratory fisheries 
(Bourdages and Goudreau 2012). .......................................................................... 28 

Figure 3. Von Bertalanffy growth curves estimated from growth rings on the shells of 
Arctic surfclams from some eastern Canadian beds. ............................................. 29 

Figure 4. New England hydraulic dredge (Bourdages and Goudreau 2012). ................ 29 
Figure 5. Management areas for the Arctic surfclam fishery in Quebec (Bourdages and 

Goudreau 2012). .................................................................................................... 30 
Figure 6. Annual Arctic surfclam landings in Quebec by marine region. ....................... 30 
Figure 7. Annual Arctic surfclam landings in Quebec by fishing area group. ................. 31 
Figure 8. Location of known Arctic surfclam beds in Area 1A. ...................................... 32 
Figure 9. Annual Arctic surfclam landings in Area 1A. ................................................... 33 
Figure 10. Fishing effort in area dredged (km2) and annual exploitation rates in Area 1A.

 ............................................................................................................................... 33 
Figure 11. Annual catch per unit effort (± 95% confidence interval) in Area 1A. ........... 34 
Figure 12. Annual distribution of the size at landing of Arctic surfclams measured by bed 

in Area 1A. ............................................................................................................. 35 
Figure 13. Estimated annual mean size (± 95% confidence interval) at landing of 

surfclams in Area 1A. ............................................................................................. 36 
Figure 14. Intensity of exploitation from 1993 to 2020 in the Les Escoumins (A), 

Forestville (B) and Cap Colombier (C) beds in Area 1A. ........................................ 37 
Figure 15. Annual distribution of fishing effort per 10 seconds of longitude in Area 1A. 38 
Figure 16. Location of known Arctic surfclam beds in Area 1B. .................................... 38 
Figure 17. Annual Arctic surfclam landings in Area 1B. ................................................. 39 
Figure 18. Fishing effort in area dredged (km2) and annual exploitation rates in Area 1B.

 ............................................................................................................................... 39 
Figure 19. Annual catch per unit effort (± 95% confidence interval) in Area 1B. ........... 40 
Figure 20. Annual distribution of the size at landing of Arctic surfclams measured by bed 

in Area 1B. ............................................................................................................. 40 
Figure 21. Estimated annual mean size (± 95% confidence interval) at landing of 

surfclams in Area 1B. ............................................................................................. 41 
Figure 22. Intensity of exploitation from 1993 to 2020 in the Cap Colombier bed in 

Area 1B. ................................................................................................................. 41 
Figure 23. Annual distribution of fishing effort per 10 seconds of longitude in Area 1B. 42 
Figure 24. Location of known Arctic surfclam beds in Area 2. ....................................... 43 
Figure 25. Annual Arctic surfclam landings in Area 2. ................................................... 44 
Figure 26. Fishing effort in area dredged (km2) and annual exploitation rates in Area 2.

 ............................................................................................................................... 44 
Figure 27. Annual catch per unit effort (± 95% confidence interval) in Area 2. .............. 45 
Figure 28. Annual distribution of size at landing of Arctic surfclams measured by bed in 

Area 2. ................................................................................................................... 46 
Figure 29. Estimated annual mean size (± 95% confidence interval) at landing of 

surfclams in Area 2. ............................................................................................... 47 



 

vi 

Figure 30. Intensity of exploitation from 1993 to 2020 in the Baie-Trinité Centre bed in 
Area 2. ................................................................................................................... 47 

Figure 31. Annual distribution of fishing effort per 10 seconds of longitude in Area 2. .. 48 
Figure 32. Location of known Arctic surfclam beds in Area 3A. .................................... 48 
Figure 33. Annual Arctic surfclam landings in Area 3A. ................................................. 49 
Figure 34. Fishing effort in area dredged (km2) and annual exploitation rates in Area 3A.

 ............................................................................................................................... 49 
Figure 35. Annual catch per unit effort (± 95% confidence interval) in Area 3A. ........... 50 
Figure 36. Annual distribution of the size at landing of Arctic surfclams measured by bed 

in Area 3A. ............................................................................................................. 51 
Figure 37. Estimated annual mean size (± 95% confidence interval) at landing of 

surfclams in Area 3A. ............................................................................................. 52 
Figure 38. Intensity of exploitation from 1993 to 2020 in the Ste-Marguerite (A) and west 

Moisie River (B) beds in Area 3A. .......................................................................... 53 
Figure 39. Annual distribution of fishing effort per 10 seconds of longitude in Area 3A. 54 
Figure 40. Location of known Arctic surfclam beds in Area 3B. .................................... 54 
Figure 41. Annual Arctic surfclam landings in Area 3B. ................................................. 55 
Figure 42. Fishing effort in area dredged (km2) and annual exploitation rates in Area 3B.

 ............................................................................................................................... 55 
Figure 43. Annual catch per unit effort (± 95% confidence interval) in Area 3B. ........... 56 
Figure 44. Annual distribution of the size at landing of Arctic surfclams measured by bed 

in Area 3B. ............................................................................................................. 57 
Figure 45. Estimated annual mean size (± 95% confidence interval) at landing of 

surfclams in Area 3B. ............................................................................................. 58 
Figure 46. Intensity of exploitation from 1993 to 2020 in the Rivière-au-Tonnerre Est bed 

in Area 3B. ............................................................................................................. 58 
Figure 47. Annual distribution of fishing effort per 10 seconds of longitude in Area 3B. 59 
Figure 48. Location of known Arctic surfclam beds in Area 4A. .................................... 59 
Figure 49. Annual Arctic surfclam landings in Area 4A. ................................................. 60 
Figure 50. Fishing effort in area dredged (km2) and annual exploitation rates in Area 4A.

 ............................................................................................................................... 60 
Figure 51. Annual catch per unit effort (± 95% confidence interval) in Area 4A. ........... 61 
Figure 52. Annual distribution of the size at landing of Arctic surfclams measured by bed 

in Area 4A. ............................................................................................................. 62 
Figure 53. Estimated annual mean size (± 95% confidence interval) at landing of 

surfclams in Area 4A. ............................................................................................. 63 
Figure 54. Intensity of exploitation from 1993 to 2020 in the Longue-Pointe-de-Mingan 

bed in Area 4A. ...................................................................................................... 63 
Figure 55. Annual distribution of fishing effort per 10 seconds of longitude in Area 4A. 64 
Figure 56. Location of known Arctic surfclam beds in Area 4B. .................................... 64 
Figure 57. Annual Arctic surfclam landings in Area 4B. ................................................. 65 
Figure 58. Fishing effort in area dredged (km2) and annual exploitation rates in Area 4B.

 ............................................................................................................................... 65 
Figure 59. Annual catch per unit effort (± 95% confidence interval) in Area 4B. ........... 66 
Figure 60. Annual distribution of the size at landing of Arctic surfclams measured by bed 

in Area 4B. ............................................................................................................. 66 



 

vii 

Figure 61. Estimated annual mean size (± 95% confidence interval) at landing of 
surfclams in Area 4B. ............................................................................................. 67 

Figure 62. Intensity of exploitation from 1993 to 2020 in the Natashquan bed in Area 4B.
 ............................................................................................................................... 67 

Figure 63. Annual distribution of fishing effort per 10 seconds of longitude in Area 4B. 68 
Figure 64. Location of known Arctic surfclam beds in Area 4C. .................................... 68 
Figure 65. Location of known Arctic surfclam beds in areas 5A and 5B. ....................... 69 
Figure 66. Annual Arctic surfclam landings in Area 5B. ................................................. 69 
Figure 67. Fishing effort in area dredged (km2) and annual exploitation rates in Area 5B.

 ............................................................................................................................... 70 
Figure 68. Annual catch per unit effort (± 95% confidence interval) in Area 5B. ........... 70 
Figure 69. Annual distribution of the size at landing of Arctic surfclams measured by bed 

in Area 5B. ............................................................................................................. 71 
Figure 70. Estimated annual mean size (± 95% confidence interval) at landing of 

surfclams in Area 5B. ............................................................................................. 71 
Figure 71. Intensity of exploitation from 1993 to 2020 in the Rocher aux Oiseaux bed in 

Area 5B. ................................................................................................................. 72 
Figure 72. Annual distribution of fishing effort per 10 seconds of longitude in Area 5B. 72 
Figure 73. Landings and total allowable catch (TAC) by fishing area. ........................... 73 
Figure 74. Catches per unit effort (kg per tow for a 1-m-wide dredge) estimated using 

logbook data of the commercial fishery, by fishing area and by year. The colour 
code represents the value of the anomaly that corresponds to the difference 
between the CPUE in a given year and the mean CPUE in the time series for each 
fishing area divided by the standard deviation of this mean. .................................. 74 

  



 

viii 

ABSTRACT 
This research paper presents the Arctic surfclam biology and fishing activities. It also presents 
data and methodologies used to prepare the Quebec inshore waters Arctic surfclam stock 
assessment after the 2020 fishing season. This information was presented at the peer review 
meeting held virtually on February 22, 2021. 
Mean annual Arctic surfclam landings in Quebec totalled 587 t from 2018 to 2020, an 
8% decrease compared with the 2015–2017 period. The North Shore accounted for 99% of 
landings and the Magdalen Islands for 1%. The annual Total Allowable Catch (TAC) for the 
2018–2020 period averaged over 80% in areas 3A and 3B. There was no fishing in areas 1A 
and 5B in 2018 and Area 2 was fished in 2018 only. There was no fishing in Area 1B from 2018 
to 2020 and areas 4C and 5A remain unexploited. Mean catches per unit effort (CPUE) from 
2018 to 2020 are above the time series (1993–2019) median for Area 3A but below it for 
areas 1A, 2, 3B, 4A, 4B and 5B. Mean sizes at landing of surfclams from 2018 to 2020 are 
above the time series median for areas 2, 3A, 4B and 5B, but below it for areas 1A, 3B and 4A. 
The exploitation rate in each area (based on the dredged surface area) was below the 
recommended rate of 3% in all fishing areas. According to the existing decision rules, only 
Area 3A meets all the conditions for a 6% quota increase. Maintaining the current quota in the 
other areas should not affect the status of the resource. Fishing effort in one fishing area should 
be distributed within and among beds in order to limit the possibility of local overexploitation. 
 



 

1 

INTRODUCTION 
A review and assessment of Arctic surfclam (Mactromeris polynyma) stocks in Quebec inshore 
waters has been conducted for several years by Fisheries and Oceans Canada (DFO). 
Assessments are conducted every three years. This report presents the data and analytical 
methods used for the assessment to produce the Science Advisory Report (DFO 2021) after the 
2020 fishing season. 

ARCTIC SURFCLAM DISTRIBUTION AND BIOLOGY 

DISTRIBUTION 
Arctic surfclam (Figure 1) can be found along the west coast of the Atlantic, from Labrador to 
Rhode Island (Rowell and Amaratunga 1986, Roddick and Kenchington 1990); on the Pacific 
coast, from Alaska to Vancouver Island (Hughes and Bourne 1981); and on the coast of Russia. 
A Canadian study showed that there were no genetic differences between the Atlantic 
populations, but there was a difference between the Atlantic and Pacific populations (Cassista 
and Hart 2007). 
Arctic surfclam (Mactromeris polynyma) is a sedentary endobenthic bivalve mollusc that lives 
buried in sediments. Arctic surfclams rarely make voluntary movements, but when dislodged 
from the sediment, either by currents, waves or fishing gear, they have the ability to rebury 
themselves as they are strong and active burrowers (DFO 2007). Burying depth depends on the 
length of their siphon. Larger individuals are found deeper in the sediment. They use their 
inhalant siphon to feed, filtering small organisms suspended in water. 
This species is found buried in sandy sediments. More specifically, the sediment composition of 
its habitat has been assessed on a few occasions during exploratory fisheries. Bourassa et al. 
(2008) observed on a surfclam bed on the Middle North Shore that the sediments consisted on 
average of 98% to 99% sand, 0.5% to 1% gravel and less than 0.5% clay. Using divers, 
Lambert and Goudreau (1995a) observed the presence of Arctic surfclams on sand and sandy 
mud sites. Brulotte (1995) did not observe any surfclams at the sites explored where the 
sediment was muddy. 
Surfclams gather in aggregations called “beds” on the sublittoral zone or under the low tide line. 
During exploratory fisheries on the North Shore, surfclams were observed at depths of 1 to 46 m 
and maximum densities were observed at depths of 15 to 20 m. The distribution of these beds is 
closely related to large North Shore rivers. These rivers release large quantities of sediment at 
their mouths, which favours the presence of this species. Lambert and Goudreau (1999) 
recorded temperatures ranging from 1 to 9 ºC at a 13-m depth at the Rivière-au-Tonnerre study 
site from May to November 1996. In the Magdalen Islands, the species can be found at depths 
ranging from 25 to 60 m. 
The known distribution of Arctic surfclam in Quebec inshore waters is presented in Figure 2. 
This distribution is based on several sources of information, namely exploratory fisheries, 
scientific surveys and fishers’ logbooks. From these positions, it was possible to delineate the 
beds by setting their spatial boundaries at positions where the surfclam density becomes zero 
or very low over a distance of 1 km (Lambert and Goudreau 1997). This delineation is adjusted 
based on new data in each stock assessment and was done using ArcGIS Pro (version 2.5.0) 
by creating polygons around georeferenced positions where the surfclam was present. The 
distributions of mean densities and probabilities of occurrence, having been calculated within 



 

2 

each 2-minute latitude and longitude square, are presented in Figures 26 and 27 in Bourdages 
et al. (2012).  

GROWTH 
Arctic surfclams have a slow growth rate, which appears to vary according to the species’ 
distribution (Table 1 and Figure 3; Landry et al. 1992, Lambert and Goudreau 1999, Bourassa et 
al. 2008; Ziccardi et al. 2012, Trottier and Goudreau 2015). On the North Shore, they require 
between 13 and 16 years to reach a size of 80 mm (anteroposterior length); in the Magdalen 
islands, they require more than 20 years. Reaching a size of 100 mm takes 20 to 25 years on 
the North Shore and about 35 years in the Magdalen Islands. The mean size of surfclams fished 
on the North Shore and in the Magdalen Islands is around 110 and 100 mm, respectively, which 
would represent individuals of at least 25 years of age. The maximum size observed in the 
commercial fishery is 150 mm on the North Shore and 130 mm in the Magdalen Islands. These 
specimens could be more than 75 years old, which indicates that this mollusc has a long 
lifespan. 
Lambert and Goudreau (1999) and Bourassa et al. (2008) studied the growth of the surfclam in 
the wild. To do this, in 1995 and 2004, they marked surfclams with a small numbered tag glued 
to their shell. These surfclams were then returned to the study site. The next year, 36 surfclams 
were recaptured. According to these studies, growth is highly variable among individuals. 
Individuals between 40 and 80 mm had a growth of about 5 mm while those over 100 mm had a 
mean growth of about 1 mm. Lambert and Goudreau (1999) studied growth in the laboratory. 
They observed increases greater than what had been observed in the wild in the smallest 
individuals. A graphical representation of different annual growth models was made using data 
from the work done by Bourdages and Goudreau (2012). 
There also appears to be a negative relationship between individual density and growth 
(Lambert and Goudreau 1999). 

REPRODUCTION 
The Arctic surfclam is dioecious, meaning that the sexes are separated. Lambert and Goudreau 
(1997) studied its reproductive cycle and observed a sex ratio of nearly 1:1 for individuals 
between 50 and 80 mm and clearly in favour of females for individuals over 80 mm. They also 
observed that the majority of individuals over 62 mm had spawned or possessed mature 
gonads, but that at this size, their contribution to the population’s reproductive potential was low 
because like other bivalve species, gamete production is considered to increase with size 
(Langton et al. 1987). Similarly, they observed that spawning occurred primarily from late June 
through mid-July and that there may be secondary spawning in the fall. Reproduction is 
synchronous and gamete fertilization occurs in the water column. After eggs hatch, a pelagic 
larval stage extending over a few weeks precedes benthic life. From laboratory observations, 
Davis and Shumway (1996) estimated that larval metamorphosis occurred after 24 days of 
growth at 15 ºC and after 42 days at 10 ºC. 



 

3 

DESCRIPTION OF THE FISHERY 
The first exploratory fisheries in the northern Gulf took place in 1990 in the Magdalen Islands 
and in 1991 on the North Shore (Landry et al. 1992). Subsequently, other exploratory fisheries 
took place on the North Shore (Mercier 1992, Cyr 1994, Lambert and Giguère 1994, Lambert 
and Goudreau 1995b, Lepage 1994), on the shores of the Lower St. Lawrence, and on the north 
shore of the Gaspé Peninsula (Brulotte 1995). These exploratory fisheries located several beds. 
From that time onward, the fishery began to develop more abundantly on the North Shore and 
in the Magdalen Islands. The first landings were recorded in 1993 (Lambert and Goudreau 
1997). In Quebec, the Arctic surfclam fishery is complementary because fishers engage in other 
fisheries during the year. 
The Arctic surfclam fishery is conducted using a New England hydraulic dredge (Figure 4). It is 
a sophisticated dredge designed to (1) be extremely efficient, (2) have a low bycatch rate and 
(3) retain few undersized surfclams (Northeast Region Essential Fish Habitat Steering 
Committee 2002). According to Lambert and Goudreau (1995a), the effectiveness of this type of 
dredge is estimated at more than 90% for surfclams measuring more than 80 mm. 
Depending on the management measures specific to each region, the typical dredge used in 
Quebec is 1.83 or 2.13 m (6 or 7 ft.) wide by 1.83 m (6 ft.) long. Spacing between the basket 
bars must be at least 3.175 cm. The dredge’s cutting bar is adjusted to fish at a depth of about 
20 cm and the water jet pressure is adjusted to about 414 to 715 kPa (60 to 75 PSI). The water 
jets penetrate the sediment in front of the dredge to a depth of about 20 cm, liquefying the 
sediment. The endobenthic organisms thus released are then collected in the bucket when the 
dredge passes. The dredge is towed at a speed of about 11 m/min (0.35 knots) for about 
10 minutes per tow at depths between 10 and 20 m, but the depth may vary depending on the 
fishing site. 

FISHERY MANAGEMENT 
Quebec has 10 fishing areas: 8 on the North Shore and 2 in the Magdalen Islands (Figure 5). 
This inshore fishery is managed throughout the area by a number of licences, a fishing season, 
a total allowable catch (TAC) and a minimum catch size of 80 mm (Table 2). In 2020, 
15 permanent licences and 3 exploratory licences were issued. Some licences give access to 
more than one fishing area. The TAC by fishing area and year is presented in Table 6. 

CONSERVATION APPROACH 
A workshop on biological reference points for invertebrates was held in Halifax in 2002 (Smith 
2003). The findings of this workshop were presented for several species that were divided by 
life cycle category. The Arctic surfclam was in the group of species with a larval dispersal phase 
and with sessile adults that are open-water spawners (and release their gametes into the water 
where fertilization occurs). These species are found in beds and are highly fecund, and fishing 
operations can be very disruptive to the habitat. Most conservation strategies for these species 
include providing a refuge area for spawners or maintaining a spawning density at a level that 
ensures effective reproduction. Catch control generally involves effort limitation through 
restricted access, seasons or protected areas. A minimum catch size equivalent to the size at 
sexual maturity is commonly brought into force. Gear restrictions exist for several fisheries. 
Rotational fishing is strongly recommended. 
The objective of the Arctic surfclam conservation approach is to protect the reproductive 
potential and genetic integrity of Quebec populations and to limit the fishery’s impact on the 
ecosystem. Management measures to achieve these objectives are effort control, sampling 
method, escapement control (selectivity) and the development of a precautionary approach. 



 

4 

To achieve this, Quebec is divided into several fishing areas where access is limited to only a 
few fishers (one to five per area, Table 2). Generally, they have access to the area for a few 
months (from July to November) and they have a TAC. In most fishing areas, there are also 
shellfish areas that are closed on account of unsafe shellfish. Although these areas are closed 
within the scope of the Canadian Shellfish Sanitation Program, these closures protect some of 
the surfclam population from being harvested, but their abundance and contribution to 
reproductive potential remains unknown. The density of spawners is critical for reproductive 
success, and protecting small areas with a high density of adults may be beneficial for the 
population. In addition, portions of beds with a high density of pre-commercial size (< 80 mm) 
surfclams should be protected from the fishery because they are less evenly distributed within 
the beds compared with commercial-size surfclams. The exploitation rate per bed must remain 
low given the species’ low productivity. Currently, the dredged area remains relatively small 
compared with the known area of the beds. 
The current minimum catch size of 80 mm allows individuals to reproduce a few years before 
being vulnerable to the fishery. In addition, the regulated spacing of the dredge bars minimizes 
catching surfclams smaller than 80 mm; however, even if they are not caught, the survival rate 
of these surfclams is unknown after the dredge passes. 
Population monitoring and management measures are necessary for this conservation 
approach. The monitoring tools already in place should be maintained and others should be 
developed (in italics):  

• Tracking of catch per unit effort (CPUE) by logbook and purchase receipt. 

• Dockside sampling with appropriate spatial coverage. 

• Using the logbook to monitor spatial distribution of fishing effort. 

• A vessel monitoring system (VMS) would improve knowledge of bed distribution, exploited 
areas and fishing patterns. 

• Knowledge of bycatch and incidental mortality could be improved. 

Research surveys provide basic knowledge of the species’ biology. Such surveys conducted 
before exploiting a bed would provide information on the demographic structure of the virgin 
population. A periodic survey would allow for management based on exploitable biomass and 
on reference points. 
According to Richard and Maguire (1998), future harvesting strategies should be based on 
stock-specific reference points and pre-established decision rules. Objectives and reference 
points associated with the Arctic surfclam fishery are not yet developed. Discussions between 
the fishing industry and DFO will be required in order to develop this precautionary approach. 
Development of reference points based on virgin biomass will not be possible for beds that have 
already been exploited where few or no data are available before exploitation begins. However, 
it would be wise to acquire a good knowledge before exploitation starts if new beds are 
discovered in the future. 

DATA SOURCE AND ANALYSES 

COMMERCIAL FISHERY DATA 
Commercial Arctic surfclam fishery data are derived from three separate sources of information: 
the fisher’s logbook, the purchase receipt and commercial catch sampling conducted by DFO. 



 

5 

The fishers fill in their logbooks on each fishing day. The logbooks contain the date, the weight 
of the catch, the position (latitude and longitude) at the beginning and end of the fishing day, the 
fishing quadrilateral (10-minute latitude and longitude square), the fishing duration, the number 
of tows, the width of the dredge and the number of crew members. The logbook data are 
entered into a database by DFO area offices. The fishing activities reported in the logbooks are 
then paired with the plant purchase receipts to account for each operator’s landings. At the end 
of the season, these data are extracted for DFO’s Ecosystems and Oceans Science Sector. The 
data are then validated and corrected as needed by the scientists. Outliers are removed from 
the calculations. In late fall, fishing statistics are updated for the current year and the two 
previous years. Data from the two previous years are still considered preliminary. 
At the beginning of this fishery, from 1993 to 1997, with some exceptions, fishers cooperated 
with DFO by completing a detailed logbook for each fishing tow. The position, depth, duration 
and weight caught in each tow were recorded in the logbook. In those days, fishers did a lot of 
exploring. The information obtained was very helpful in defining the extent of the Arctic surfclam 
beds. In addition, from these data, the mean duration of a tow was estimated, as was the fishing 
speed. In order to make these data comparable with the data currently collected in the 
logbooks, i.e., data per fishing day, the information from the fishing tows on the same day was 
summed up or an average per day was calculated. These aggregate data were used to estimate 
CPUE and to define the areas exploited. 
The function of the DFO commercial sampling program is to characterize the individuals 
harvested by the fishery in order to complete the information essential to the assessment of the 
impact of exploitation on marine resources. In the case of the Arctic surfclam, this sampling 
takes place at the dock given that: 
1. the dredge is very selective in catching only individuals of legal size, so the release of Arctic 

surfclams is minimal.  
2. the species is not processed at sea; it is landed in its entirety.  
3.  bycatch is very low. 
Since 2004, dockside sampling has taken place either upon landing or at the plant. A sample of 
about 150 surfclams is taken and the size of each is measured along the longitudinal axis to the 
nearest millimetre. Information on the source of the catch is also compiled. The number of 
samples requested annually by Science is presented in Table 3. Because of the surfclam’s slow 
growth during the fishing season, there are no details on when to collect the samples. Landings 
can therefore be sampled at any time during the fishing season. The goal is to sample 6 to 10 
fishing activities per area annually. 

Landings 
Landings are expressed in live weight (the whole surfclam with shells). Landings from the same 
bed, fishing area or marine region are totalled by year. 

Fishing effort 
Much of the information available in the logbook can be used to define the fishing effort (for 
example, the fishing duration expressed in hours, the number of fishing days, the number of 
tows and the width of the dredge). The number of fishing tows was preferred to describe fishing 
effort since it is more consistently noted among fishers. 
The number of tows can be converted to dredged area. To do this, knowledge of the mean 
duration of a tow, the fishing speed and the width of the dredge is required. The mean duration 



 

6 

of a tow was estimated at 10.346 minutes in the logbooks from 1993 to 1997. It would be 
appropriate to reassess this duration, which may have varied over time because the duration 
varies from tow to tow. However, analysis of these historical data did not reveal any significant 
effects from fishers or the fishing area. The fishing speed used is 11 m/min (0.35 knots) (Jean 
Lambert, DFO, pers. comm.). This fishing speed is comparable to speeds observed in research 
projects conducted with fishers from 1993 to 1997. However, a dredging speed of 22 m/min 
(0.7 knots) has been used since 2013 for areas 2, 3A and 3B after a change in the fishing 
pattern. The width used is the width of the dredge cutting bar provided in the logbook. Effort is 
also expressed in fishing days. In this case, it is the number of daily trips made by fishers in the 
area. 
The distribution of daily fishing positions was studied in relation to the longitude of the activities. 
The longitude represents the axis of the coast on the North Shore and the distribution of the 
beds. The latitudinal extent of the fishing sites is relatively small. The number of fishing days 
was added up by year for each 10-second longitude interval, which corresponds to a distance of 
about 310 m. The distribution of this effort is presented by year and by area and provides 
information on the dynamics of the spatial distribution of fishing effort, i.e., which beds are 
exploited and how effort shifts within a bed and between years. 
The calculation of fishing effort is mostly based on variables derived from logbooks and some 
constants assessed during the 1993–1997 commercial fishery. Any change in fishing technique 
(for example, an increase in dredging speed) would have a direct impact on areas dredged and 
exploitation rates. 

Catch per unit effort 
Annually, CPUE is estimated from logbook data using a Jackknife estimator (Smith 1980). The 
Jackknife estimator 𝑅𝑅𝐽𝐽 is the average of n quantities: 

𝑅𝑅−𝑗𝑗′ = 𝑛𝑛𝑃𝑃
𝐸𝐸 − (𝑛𝑛 − 1)𝑅𝑅−𝑗𝑗, 

where n is the number of activities in the fishing area, P and E are the total catch and total effort 
in the area in question, and 𝑅𝑅−𝑗𝑗 = ∑𝑃𝑃𝑖𝑖𝑗𝑗 /∑𝐸𝐸𝑖𝑖𝑗𝑗 with the jth observation removed. The catch is 
expressed in kg live weight and the effort in number of tows for a 1-metre-wide dredge (number 
of tows multiplied by the width of the dredge). 

The variance estimate of 𝑅𝑅𝐽𝐽 is calculated as follows: 

𝑉𝑉�𝑅𝑅𝐽𝐽� = 1
𝑛𝑛(𝑛𝑛−1)�(𝑅𝑅

−𝑗𝑗′−𝑅𝑅𝐽𝐽
)2

𝑛𝑛

 

CPUE is presented with its 95% confidence interval and is expressed in kg per tow for a 
1-metre-wide dredge and in g/m2, assuming that an area of 113.8 m2 is covered during a tow by 
a 1-metre-wide dredge, as defined above. 

Exploitation rate indicator 
From the daily positions provided in the logbooks since 1993, it was possible to map the 
intensity of exploitation on the beds with the Kernel density analysis tool in the ArcGIS Pro 
(version 2.5.0) Spatial Analyst suite. Intensity of exploitation was estimated on a 5x5-metre grid 
by implementing a search ellipse constraint with a 200-m radius. This radius approximates the 
fishers’ range as revealed by logbook data from 1993 to 1997. At that time, fishers recorded the 
positions of all the day’s tows and focused their effort locally within a radius of about 200 m 
before heading out. 



 

7 

The area of the exploited zone in each bed that circumscribes 100% of the fishing intensity 
(fishing intensity > 0) was estimated from the maps of intensity of exploitation. Subsequently, a 
second area corresponding to the area where 95% of the intensity of exploitation is distributed 
was estimated. The number of observations used to estimate these surface areas and the two 
estimated areas are presented by bed in Table 10. 
An exploitation rate indicator was developed using the quotient between the area dredged 
annually by fishers and the area where 95% of the intensity of exploitation is concentrated; that 
is: 

𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝑛𝑛 𝑟𝑟𝐸𝐸𝐸𝐸𝑟𝑟𝑏𝑏𝑏𝑏𝑏𝑏,𝑦𝑦𝑏𝑏𝑦𝑦𝑦𝑦 =
𝑑𝑑𝑟𝑟𝑟𝑟𝑑𝑑𝑑𝑑𝑟𝑟𝑑𝑑 𝐸𝐸𝑟𝑟𝑟𝑟𝐸𝐸𝑏𝑏𝑏𝑏𝑏𝑏,𝑦𝑦𝑏𝑏𝑦𝑦𝑦𝑦

𝑟𝑟𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝑟𝑟𝑑𝑑 𝐸𝐸𝑟𝑟𝑟𝑟𝐸𝐸𝑏𝑏𝑏𝑏𝑏𝑏,𝑦𝑦𝑏𝑏𝑦𝑦𝑦𝑦
 

The exploitation rate is estimated by year and by bed. However, the exploitation rate for some 
beds was calculated using the total area of these beds because of the low fishing intensity (less 
than 30 fishing days in all years). An exploitation rate for each area is also calculated for this 
assessment period using the mean dredged area for the years 2018–2020 divided by the area 
where 95% of the fishing intensity for that same area is concentrated. 

COMMERCIAL SAMPLING 
A boxplot is used to measure the size at landing of surfclams by year and by bed. The boxplot is 
a quick way to present several descriptive statistics of the variable being studied. To begin with, 
the rectangle drawn runs from the first quartile to the third quartile and is intersected by the 
median so that 50% of the observations fall within the boundaries of the box. The lower end of 
the whisker represents the minimum value of an observation that is above the low boundary 
value while the upper end represents the maximum value of an observation that is below the 
high boundary value. These limits deviate by 1.5 times the height of the box above or below the 
box boundaries. Lastly, extreme observations lie outside the boundaries of the whisker and are 
represented by dots. The 5th and 95th percentiles of the distribution were also added to the 
graph. 
An analysis of variance model (LS Means Analysis of Variance) was used to estimate the mean 
size at landing of surfclams to account for differences among the beds. The fixed factors in the 
model are year and bed and a random factor is assigned to the sample. The year and bed 
factors are significant in the analyses. For some areas, a few beds had to be removed from the 
analysis because they had not been sampled frequently enough. Therefore, the Îles de Mai 
(Area 2) and northwest of Grosse-Île (Area 5B) beds were not used to estimate the mean size 
indicator, nor was the sample collected in 1998 at Natashquan. 

RESEARCH SURVEYS 
Research surveys conducted on the North Shore in 2009 and 2010 as part of the Fisheries 
Science Collaborative Program (FSCP) showed a very localized presence of high densities of 
surfclams measuring less than 80 mm in the Longue-Pointe-de-Mingan (Area 4A) and 
Natashquan (Area 4B) beds and lower densities in the Forestville (Area 1A) bed (Bourdages 
and Goudreau 2012). Furthermore, commercial size surfclams were more evenly distributed 
within these beds compared with pre-commercial size surfclams (< 80 mm) (Trottier and 
Goudreau 2015). This work also showed that the highest densities of surfclams (< 80 mm and 
≥ 80 mm) were found in the same locations on the Longue-Pointe-de-Mingan bed compared 
with the 1994 study by Lambert and Goudreau (1995b) (Trottier and Goudreau 2015). 
Age readings were taken on a sample of surfclams collected during Bourdages and Goudreau’s 
work (2012) in 2010 on the Natashquan bed. Age was estimated by assessing the number of 



 

8 

growth rings on the shell chondrophore of each individual. The parameters of the growth curve 
according to the von Bertalanffy model were estimated and these parameters are presented in 
Table 1 and Figure 3. 
Given this species’ sedentary nature and slow growth, it would be worthwhile to consider the 
cumulative effects of exploitation on the beds. Moreover, the density and biomass of several 
beds are not known, and it would be useful to acquire new knowledge on this subject. 

ASSESSMENT OF THE RESOURCE STATUS 
In order to facilitate the reading and use of this research paper, the various tables and figures 
are placed in continuous form at the end of the document. Initially, the overall results are 
presented by region or by area grouping. Therefore, there are landings (Tables 4 and 5 and 
Figures 6 and 7), fishing effort in days (Table 7) and dredged area (Table 8), CPUE (Table 9), 
exploitation rate (Table 11) and mean size estimate (Table 12). 
Thereafter, the results are presented by fishing area (Figures 8 to 74). All information from one 
area is grouped together. For each fishing area, the order of the different figures is the same, 
i.e., bed location (Figures 8, 16, 24, 32, 40, 48, 56, 64 and 65), landings (Figures 9, 17, 25, 33, 
41, 49, 57 and 66), fishing effort in dredged area (Figures 10, 18, 26, 34, 42, 50, 58 and 67), 
CPUE (Figures 11, 19, 27, 35, 43, 51, 59 and 68), distribution of sizes at landing of surfclams by 
bed (figures 12, 20, 28, 36, 44, 52, 60 and 69), mean size (Figures 13, 21, 29, 37, 45, 53, 61 
and 70), intensity of exploitation (Figures 14, 22, 30, 38, 46, 54, 62 and 71) and, lastly, 
distribution of fishing effort (Figures 15, 23, 31, 39, 47, 55, 63 and 72). 
The median presented on the effort, CPUE and mean size figures represents the time series 
median value from 1993 to 2019, which excludes the last year. 

REVIEW OF INDICATORS 
Arctic surfclam is distributed in heterogeneous densities along the entire North Shore, from the 
Lower Estuary (Les Escoumins) to the Lower North Shore (Blanc-Sablon). There are more than 
25 known beds along this coast; these beds cover a total area of 197 km2 (Figure 2 and 
Table 11). In the Magdalen Islands, surfclam is present everywhere around the islands at a 
distance of about 25 to 40 km from the coast and at depths ranging from 25 to 60 m (Figure 65). 
There are four known beds in this region, and they cover a total area of 464 km2 (Table 11). The 
area of the beds varies greatly. For example, on the North Shore, the smallest bed is 0.6 km2 
while the largest is 60 km2, while in the Magdalen Islands, the smallest is 9 km2 and the largest 
is 214 km2. 
Fishing effort is not distributed uniformly in the surfclam’s known habitat. Fishers prefer to go to 
sites with high concentrations of commercial size surfclams in the beds. Over the past three 
years, fishing efforts have been made on 14 beds on the North Shore and on one bed in the 
Magdalen Islands (Table 11). 
In Quebec, mean landings over the last three years totalled 587 t, down 8% compared with the 
2015–2017 period (Table 4, Figures 6 and 7). This decrease is due to fishing inactivity in 
areas 1A and 5B in 2018 and in Area 2 in 2019 and 2020. In addition, Area 1B has not been 
exploited in the past four years. From 2018 to 2020, the North Shore accounted for 99% of 
landings and the Magdalen Islands for 1%. Figure 73 shows the proportion of the TAC that was 
reached by year and area. Two areas remain unexploited, namely areas 4C and 5A. The annual 
TAC for the 2018–2020 period averaged over 80% in areas 3A and 3B. For areas 1A, 2, 4A, 4B 
and 5B, the TAC for the same period averaged 5% to 76%. 



 

9 

The mean catches per unit effort (CPUE) for the 2018–2020 period were above the time series 
medians for Area 3A, but below them for Areas 1A, 2, 3B, 4A, 4B and 5B (Table 9). Figure 74 
shows the difference between the annual CPUE and the time series mean for each fishing area. 
Until now, throughout each area, fishers were able to maintain good yields by moving over the 
same bed or from one bed to another. On a small scale, the fishery could still bring about a 
decrease in density and mean size and, consequently, in CPUE. 
The mean size at landing is high in all areas compared with the legal size of 80 mm (Table 12). 
The mean sizes for the 2018–2020 period are above the time series median for areas 2, 3A, 4B 
and 5B, but below it for areas 1A, 3B and 4A (Table 12). For most areas, fishers were able to 
maintain high sizes by moving their fishing effort. The number of individuals measuring less than 
80 mm in landings is minimal (about 0.6%) because of the dredge’s selectivity. 
The mean exploitation rate in each area for the 2018–2020 period is below the recommended 
rate of 3% in all fishing areas (Table 11). The exploitation rates are below the recommended 
limit except in two beds, where it is exceeded: Baie de Moisie west of Area 3A (3.4%) and 
Rivière-au-Tonnerre east of Area 3B (4.0%). Such exploitation rates may not be sustainable in 
the long term. 

Decision rules 
Quota increases must be conservative, as the Arctic surfclam’s low growth rate and 
sedentariness make certain beds vulnerable to overexploitation. According to the guidelines 
established to recommend quota adjustments in each fishing area, increases should not exceed 
6% per three-year period. A quota cannot be increased unless over 80% of it, on average, has 
been reached consistently during the assessment period and the CPUE and mean size 
indicators are above the time series median. In addition, the exploitation rate in the area should 
be below 3%. 
According to the existing decision rule (Bourdages and Goudreau 2012), only Area 3A meets all 
the conditions for a 6% quota increase. The status quo is recommended for all other areas 
(Table 13). 
1. We should also start thinking now about adding conditions to this decision rule for situations 

where the indicators would show a negative signal because of exploitation. In this respect, 
Bourdages and Goudreau (2012) proposed three types of reference points that could be 
used to develop a precautionary approach. In short, reference points based on indicators of 
CPUE and of mean size at landing.  

2. The exploitation rate calculated from the dredged areas.  
3. Knowledge of exploitable biomass through research surveys could be explored.  
Finally, the application of this rule is only reviewed at the time of the stock assessment every 
three years or if a negative signal of the exploitation of the resource is perceptible at the time of 
the annual indicator update. 

ECOSYSTEM CONSIDERATIONS 
A science advisory report on the potential effects of mobile gear on benthic habitats and 
communities was published by DFO’s Canadian Science Advisory Secretariat in 2006 (DFO 
2006). The effects of mobile gear are not uniform, but are at least a function of these 
considerations: (1) the particular characteristics of the benthic habitats, including the natural 
disturbance regime, (2) the species present, (3) the type of gear used, and (4) previous human 
activities. In applying the precautionary principle to the management of ecosystem effects from 



 

10 

human activity, it is important to consider the ability of ecosystem components to recover from 
disturbances. 

Habitat 
Use of the hydraulic dredge has an immediate impact on substrate and benthic organisms. 
Dredge water jets liquefy the sediment up to 20 cm deep to collect most of the larger organisms 
and cause sedimentation adjacent to the dredge’s path (Lambert and Goudreau 1995a, 
Gilkinson et al. 2003). The greatest impact of this fishery is to remove the largest surfclams from 
a bed, either through fishing or incidental mortality. Sedentariness, irregular recruitment and low 
growth rate mean that, after a stock is depleted, it could take many years for surfclams in a bed 
to recover to commercial sizes. 
The impact of this fishery was studied on Banquereau Bank at a depth of 70 m (Gilkinson et al. 
2003, 2005). At this depth, the study showed an impact on habitat and non-target organisms 
within the first two years after dredging. Juvenile surfclams were low in number throughout the 
study and no impact could be detected on them. In this time frame, there was considerable 
recovery of the composition of non-target benthic species, such as echinoderms, with a shift in 
relative abundance of the species present. Visual assessment with a camera did not reveal any 
dredge marks after one year. However, with side-scan sonar, it was still possible to see the 
marks after 10 years. At another shallower site, on Sable Island Bank at a 40-m depth, half of 
the marks could no longer be seen with side-scan sonar after one year (Ned King, Atlantic 
Geoscience Centre, pers. comm. in DFO 2012). 
Recovery speed varies depending on the site’s depth, sediment type and degree of 
hydrodynamics. Shallower sites with higher hydrodynamics produced by currents seem to 
recover their initial state of sediment and meiofaunal/macrofaunal composition between a few 
days to a few months (Hall et al. 1990, Constantino et al. 2009, Tuck et al. 2000). The rapid 
recovery could be caused by the high hydrodynamics and the more mobile nature of the sandy 
bottoms, favouring communities that are more resilient to disturbances (Zajac and Whitlatch 
2003). 
In Quebec, the fishery is carried out mainly along the coast on sandy bottoms, at depths of 10 to 
25 m on the North Shore and about 30 m in the Magdalen Islands. Therefore, a more rapid 
recovery could be assumed on these fishing grounds than what was observed on Banquereau 
Bank. The overall effect of dredging on some elements of the benthic community could be 
mitigated by the fact that the fishery occurs on fairly mobile and well-stratified sand (Northeast 
Region Essential Fish Habitat Steering Committee 2002). At these depths, sandy sediments are 
disturbed and resuspended naturally by storms, waves and, in some places, strong currents. 
However, there are some uncertainties about the effect of dredging on benthic productivity in 
general. 
The mean annual surface areas dredged from 2018 to 2020 totalled 0.656 km2 on the North 
Shore and 0.015 km2 in the Magdalen Islands. The total area dredged since the beginning of 
the fishery in 1993 is about 14.9 km2 on the North Shore and 2.0 km2 in the Magdalen Islands 
(Table 11). The footprint of this fishery on this habitat is relatively small compared with the 
surface areas of known beds—197 km2 on the North Shore and 464 km2 in the Magdalen 
Islands—and represents about 7.6% and 0.4% of the known surfclam habitat on the North 
Shore and in the Magdalen Islands, respectively. 

Species present 
Bourdages and Goudreau (2012) identified 15 research projects on the Upper and Middle North 
Shore from 1993 to 2010 that provided information on the species composition of the Arctic 



 

11 

surfclam beds. These projects were conducted using a hydraulic dredge with a 20-mm liner 
(research component) inside the bucket and without a liner (commercial fishing component). In 
summary, the proportion in number of different species caught at the fishing sites varies 
spatially. On the Upper and Middle North Shore, the dominant species in research survey 
situations were Arctic wedge clam (Mesodesma arctatum, 33.7%), sand dollar (Echinarachnius 
parma, 31.5%), Arctic surfclam (Mactromeris polynyma, 22.9%), Northern propeller clam 
(Cyrtodaria siliqua, 3.5%), Greenland cockle (Serripes groenlandicus, 2.4%), and truncate 
softshell (Mya truncata, 1.6%). These six species account for more than 95% of the individuals 
caught in number by the lined dredge and represent potentially catchable species on the beds. 
For the stations sampled, the densities of these species are independent of the density of the 
Arctic surfclam; moreover, these species may occur outside the surfclam beds. 
This same work has proven that in a commercial fishing situation, the dredge is very selective. 
Arctic surfclams account for 91.7% of the catch in numbers. Other species more frequently 
observed are the sand dollar, Northern propeller clam, waved whelk (Buccinum undatum), 
Greenland cockle, truncate softshell, green sea urchin (Strongylocentrotus droebachiensis), 
Arctic wedge clam, Iceland cockle (Ciliatocardium ciliatum), brittle star, Atlantic razor (Siliqua 
costata), quahog (Arctica islandica), hermit crab (Pagurus sp.), marine worm and razor clam 
(Ensis directus). Along with the Arctic surfclam, these species account for over 99.8% of 
individuals caught in commercial fishing situations. The only fish likely to be caught is the 
American sand lance (Ammodytes americanus, 0.02%). The same observation was made on 
Banquereau Bank: the proportion of non-bivalve bycatch is low (DFO 2012). 
In studies of hydraulic dredge selectivity performance, Lambert and Goudreau (1995a) 
observed an efficiency rate greater than 90% for harvesting surfclams ≥ 80 mm. Nearly two 
thirds of the surfclams ≥ 66 mm left on the bottom were damaged when the dredge passed. For 
the smallest ones, mortality associated with dredge passes could be about 15% (Dale Roddick, 
DFO, pers. comm.). Also, Lambert and Goudreau (1995a) observed that for other species not 
harvested by the dredge, the percentage of damaged individuals was low. 

CONCLUSION 
The Arctic surfclam fishery has been relatively stable in recent years with the vast majority of 
landings coming from the North Shore. Until now, throughout each area, fishers were able to 
maintain good yields by moving over the same bed or from one bed to another. The exploitation 
rate in each area (based on the dredged surface area) was below the recommended rate of 3% 
in all fishing areas. However, some beds are exploited at more than 3% in two fishing areas. 
Climate change and various environmental phenomena (for example, storm surges, shoreline 
erosion, reduced ice cover) could negatively affect Arctic surfclam populations, sandy sediments 
and recruitment to the population. We do not currently have accurate information on recruitment 
to the population from the different beds. Given the variable recruitment from year to year and 
the slow growth of this mollusc, it is important to enhance our knowledge of recruitment 
dynamics and to review some of the data used, including those used to determine the effort 
deployed and fishers’ catches per unit effort, which date back to the 1990s. The resumption of 
scientific surveys in the different fishing areas would allow the determination of more precise 
reference points and a proper precautionary approach to ensure sustainable exploitation of this 
mollusc. 



 

12 

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Lambert, J., and Giguère, M. 1994. Développement de la pêche à la mactre de Stimpson 
(Mactromeris polynyma) au Québec et efficacité de la drague hydraulique de type Nouvelle-
Angleterre. In The development of underutilized invertebrate fisheries in eastern Canada. 
Édité par L. Gendron et S. Robinson. Can. Manus. Rep. Fish. Aquat. Sci. 2247. pp. 73-81. 

Lambert, J., and Goudreau, P. 1995a. Performance de la drague hydraulique de type Nouvelle-
Angleterre pour la récolte de la mactre de Stimpson (Mactromeris polynyma). Rapp. can. 
ind. sci. halieut. aquat. 235. vii + 28 pages. 

Lambert, J., and Goudreau, P. 1995b. Mactre de Stimpson et couteau des côtes du Québec. In 
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crevette nordique et zooplancton de l’estuaire et du golfe du Saint-Laurent. Édité par 
L. Savard. Rapp. manus. can. sci. halieut. aquat. 2323. 93-103. 

Lambert, J., and Goudreau, P. 1997. Biologie et exploitation de la mactre de Stimpson 
(Mactromeris polynyma) sur les côtes du Québec. MPO Sec. can. éval. stock, Doc. rech. 
97/101. 44 p. 

Lambert, J., and Goudreau, P. 1999. Indices de croissance de la mactre de Stimpson 
(Mactromeris polynyma). Rapp. tech. can. sci. halieut. aquat. 2269. vii + 39 p. 

Landry, T.E., Wade, E., and Giguère, M. 1992. Évaluation des gisements de mactre de 
Stimpson, Mactromeris polynyma, dans le golfe du Saint-Laurent : résultats préliminaires. 
CSCPCA, Doc. rech. 92/86, 29 p. 

Langton, R.W., Robinson, W.E. and Schick, D. 1987. Fecundity and reproductive effort of sea 
scallops Placopecten magellanicus from the Gulf of Maine. Mar. Ecol. Prog. Ser. 37 : 19-25. 

Lepage, D. 1994. Distribution et abondance relative de différentes espèces de mollusques à 
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pêches de l’Atlantique (Canada). No 59. 24 p. 

Mercier, P.-H. 1992. Pêche exploratoire et estimation de l’abondance de mactres de Stimpson 
dans le secteur de Sept-Îles. Programme d’adaptation des pêches de l’Atlantique (Canada). 
No 42. 39 p. 

Northeast Region Essential Fish Habitat Steering Committee. 2002. Workshop on the effects of 
fishing gear on marine habitats off the Northeastern United States, October 23-25, 2001, 
Boston Massachussetts. Northeast Fish. Sci. Cent. Ref. Doc. 02-01. 86 p. 

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production potential for the Ocean Quahaug (Arctica islandica) and Stimpson’s surf clam 
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https://waves-vagues.dfo-mpo.gc.ca/Library/192941.pdf
https://waves-vagues.dfo-mpo.gc.ca/Library/192941.pdf
http://www.dfo-mpo.gc.ca/csas-sccs/publications/resdocs-docrech/1997/1997_101-fra.htm
http://www.dfo-mpo.gc.ca/csas-sccs/publications/resdocs-docrech/1997/1997_101-fra.htm
http://www.dfo-mpo.gc.ca/csas-sccs/publications/resdocs-docrech/1992/1992_086-fra.html
http://www.dfo-mpo.gc.ca/csas-sccs/publications/resdocs-docrech/1992/1992_086-fra.html
https://www.dfo-mpo.gc.ca/csas-sccs/publications/resdocs-docrech/1990/1990_014-eng.html
https://www.dfo-mpo.gc.ca/csas-sccs/publications/resdocs-docrech/1990/1990_014-eng.html
https://www.dfo-mpo.gc.ca/csas-sccs/Publications/ResDocs-DocRech/2012/2012_050-eng.html
https://www.dfo-mpo.gc.ca/csas-sccs/publications/resdocs-docrech/1986/1986_056-eng.html
https://www.dfo-mpo.gc.ca/csas-sccs/publications/resdocs-docrech/1986/1986_056-eng.html
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14 

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https://www.dfo-mpo.gc.ca/csas-sccs/Publications/ResDocs-DocRech/2015/2015_063-fra.html


 

15 

TABLES 

Table 1. Parameters of the von Bertalanffy growth curve estimated from growth rings on the shells of 
Arctic surfclams from some eastern Canadian beds. 

Bed Year L∞ K t0 Reference 

Rivière Moisie 1993 119.47 0.0825 0.1926 Lambert and Goudreau 1999 
Rivière-au-Tonnerre 1994 110.63 0.0980 0.4870 Lambert and Goudreau 1999 
Longue-Pointe-de-
Mingan 

2004 134.00 0.0686 0.2120 Bourassa et al. 2008 

Magdalen Islands 1992 122.37 0.0490 -0.8990 Landry et al. 1992 
Banquereau 2010 119.56 0.0830 0.0980 Roddick et al. 2012 
Natashquan 2010 125.52 0.0777 0.5899 Trottier and Goudreau 2015 

Table 2. Management measures for the Arctic surfclam commercial fishery in 2020. 

Management measures 
Fishing area 

1A 1B 2 3A 3B 4A 4B 4C 5A 5B 

Number of licences 1 1 4 2 2 2 5 3 1 4 4 
TAC (t) 80.0 68.6 54.9 85.2 93.7 174.5 425.0 170.1 204.0 113.0 

TAC Management 2 ITQ ITQ Comp. ITQ ITQ ITQ Comp. Comp. Comp. Comp. 
Start of fishing season 14/06 

 
21/07 23/03 23/03 

End of fishing season 14/11 17/10 31/12 31/12 

Hail in 100% 0% 100% 
Dredge: number 1 
Dredge: width 1.83 m 2.13 m 

Dredge: spacing between 
stems 

3.2 cm 3.175 cm 

Minimum legal size 80 mm 
1 Exploratory licence 
2 Comp. (competitive fishery), ITQ (individual transferable quota with restriction) 
  



 

16 

Table 3. Number of Arctic surfclam samples collected from 2018 to 2020 in the DFO commercial dockside 
sampling program and sampling protocol by fishing area. 

Fishing area 
Year 

Protocol 1 
2018 2019 2020 

1A - 7 10 10 samples distributed throughout the season 
1B - - - 10 samples distributed throughout the season 
2 7 - - 8 samples distributed throughout the season 

3A 9 10 10 10 samples distributed throughout the season 
3B 11 10 9 10 samples distributed throughout the season 
4A 6 8 17 10 samples distributed throughout the season 
4B 10 12 - 10 samples distributed throughout the season 
4C - - - no sample 
5A - - - 6 samples distributed throughout the season 
5B - 2 - 6 samples distributed throughout the season 

1 One sample corresponds to about 150 measured surfclams 
  



 

17 

Table 4. Arctic surfclam landings (t live weight) by region and year. 

Year 
Region 

Quebec 
North Shore Magdalen Islands 

1993 71 4 76 
1994 221 153 375 
1995 178 50 228 
1996 164 46 210 
1997 128 86 214 
1998 194 106 300 
1999 255 6 261 
2000 346 99 445 
2001 384 27 411 
2002 476 46 522 
2003 835 48 883 
2004 813 21 834 
2005 879 8 887 
2006 879 9 888 
2007 608 17 625 
2008 646 8 653 
2009 896 0 896 
2010 905 8 913 
2011 805 41 846 
2012 656 90 746 
2013 806 102 909 
2014 731 56 787 
2015 675 38 714 
2016 631 20 651 
2017 552 0 552 
2018 608 0 608 
2019 605 10 615 
2020 533 6 539 

  



 

18 

Table 5. Arctic surfclam landings (t live weight) by fishing area group and year. 

Year 
Fishing area 

1A, 1B, 2 et 3A 3B, 4A, 4B et 4C 5A et 5B 
1993 8 64 4 
1994 24 197 153 
1995 30 148 45 
1996 67 97 44 
1997 44 84 84 
1998 56 131 106 
1999 166 88 6 
2000 170 176 99 
2001 149 228 27 
2002 220 245 46 
2003 177 652 48 
2004 134 675 21 
2005 180 694 8 
2006 179 700 9 
2007 180 428 17 
2008 155 489 8 
2009 233 661 0 
2010 237 666 8 
2011 141 662 41 
2012 186 470 88 
2013 194 612 100 
2014 112 619 54 
2015 171 503 38 
2016 173 457 20 
2017 101 449 0 
2018 107 494 0 
2019 166 439 10 
2020 158 374 6 

  



 

19 

Table 6. Total Allowable Catch (TAC, t live weight) of Arctic surfclams since the beginning of the fishery in 
1993 by fishing area and year. 

Year 
Fishing area 

1A 1B 2 3A 3B 4A 4B 4C 5A 5B 
1993 - - - - - - - - - - 
1994 57 57 23 60 60 - 465 - 204 - 
1995 57 57 23 60 60 102 249 - 204 91 
1996 57 57 23 60 60 136 215 - 204 91 
1997 57 57 23 60 60 136 442 - 204 91 
1998 57 57 23 60 60 102 476 57 204 113 
1999 57 57 45 60 60 91 408 57 204 113 
2000 62 62 59 70 70 145 408 57 204 113 
2001 66 66 64 76 96 143 465 170 204 113 
2002 69 69 55 76 76 150 425 170 204 113 
2003 69 69 55 76 76 150 425 170 204 113 
2004 69 69 55 76 94 177 425 170 204 113 
2005 69 69 55 76 94 177 425 170 204 113 
2006 75 69 55 76 102 192 425 170 204 113 
2007 75 69 55 76 102 192 425 170 204 113 
2008 75 69 55 76 83 165 425 170 204 113 
2009 75 69 55 76 83 165 425 170 204 113 
2010 75 69 55 76 83 165 425 170 204 113 
2011 76 69 55 80 88 175 425 170 204 113 
2012 80 69 55 80 88 175 425 170 204 113 
2013 80 69 55 80 88 175 425 170 204 113 
2014 80 69 55 80 88 175 425 170 204 113 
2015 80 69 55 80 94 175 425 170 204 113 
2016 80 69 55 80 94 175 425 170 204 113 
2017 80 69 55 80 94 175 425 170 204 113 
2018 80 69 55 80 94 175 425 170 204 113 
2019 80 69 55 85 94 175 425 170 204 113 
2020 80 69 55 85 94 175 425 170 204 113 

  



 

20 

Table 7. Arctic surfclam fishing effort (in days) by fishing area and year. 

Year 
Fishing area 

1A 1B 2 3A 3B 4A 4B 4C 5A 5B 
1993 0 0 0 3 17 16 0 0 0 3 
1994 0 0 0 18 21 52 0 0 0 42 
1995 0 3 0 15 25 49 0 0 0 12 
1996 10 14 0 20 13 36 0 0 0 10 
1997 0 9 0 4 14 17 0 0 0 10 
1998 11 13 0 9 0 32 15 0 0 19 
1999 16 22 20 23 16 7 0 0 0 2 
2000 18 14 17 27 16 23 0 0 0 32 
2001 19 12 9 24 22 29 0 0 0 11 
2002 25 23 17 29 20 27 4 0 0 14 
2003 18 18 10 31 21 26 71 0 1 13 
2004 18 16 2 21 17 29 70 0 6 0 
2005 16 25 2 21 12 30 89 0 0 3 
2006 20 4 13 27 16 34 93 0 0 4 
2007 23 1 13 17 11 15 56 0 0 6 
2008 25 0 6 17 21 14 66 3 0 3 
2009 19 14 5 23 14 24 65 0 0 0 
2010 20 10 9 20 15 25 83 0 0 3 
2011 18 7 0 12 16 26 60 0 0 15 
2012 18 11 0 17 12 21 54 0 0 24 
2013 18 0 12 17 14 25 76 0 0 20 
2014 0 0 9 16 13 20 74 0 0 9 
2015 22 4 0 14 15 7 69 0 0 6 
2016 26 6 0 12 15 0 68 0 0 7 
2017 9 0 0 16 14 0 69 0 0 0 
2018 0 0 12 16 15 26 68 0 0 0 
2019 23 0 0 17 11 26 45 0 0 2 
2020 23 0 0 15 12 28 23 0 0 2 

  



 

21 

Table 8. Effort in area dredged (km2) in the Arctic surfclam commercial fishery by fishing area and year. 

Year 
Fishing area 

1A 1B 2 3A 3B 4A 4B 4C 5A 5B 
1993 - - - - 0.040 0.045 - - - - 
1994 - - - 0.062 0.056 0.184 - - - 0.174 
1995 - 0.004 - 0.054 0.054 0.125 - - - 0.055 
1996 0.022 0.032 - 0.055 0.025 0.070 - - - 0.086 
1997 - 0.028 - - 0.032 0.083 - - - 0.126 
1998 0.040 0.034 - 0.030 - 0.107 0.051 - - 0.160 
1999 0.026 0.068 0.056 0.065 0.041 0.033 - - - 0.026 
2000 0.060 0.033 0.058 0.085 0.043 0.099 - - - 0.244 
2001 0.053 0.026 0.030 0.090 0.066 0.096 - - - 0.069 
2002 0.075 0.095 0.058 0.108 0.071 0.102 0.017 - - 0.096 
2003 0.060 0.069 0.038 0.113 0.076 0.104 0.366 - 0.015 0.078 
2004 0.057 0.024 0.002 0.064 0.056 0.128 0.342 - 0.041 - 
2005 0.050 0.078 0.007 0.064 0.045 0.122 0.413 - - 0.017 
2006 0.057 0.018 0.058 0.077 0.063 0.141 0.507 - - 0.018 
2007 0.065 0.003 0.058 0.061 0.042 0.077 0.371 - - 0.034 
2008 0.070 - 0.023 0.058 0.063 0.053 0.378 0.002 - 0.016 
2009 0.055 0.055 0.018 0.083 0.052 0.109 0.382 - - - 
2010 0.059 0.038 0.046 0.094 0.055 0.126 0.451 - - 0.022 
2011 0.059 0.028 - 0.056 0.058 0.131 0.390 - - 0.081 
2012 0.068 0.048 - 0.076 0.049 0.104 0.304 - - 0.209 
2013 0.075 - 0.104 0.142 0.124 0.132 0.441 - - 0.197 
2014 - - 0.076 0.126 0.088 0.089 0.437 - - 0.107 
2015 0.090 0.015 - 0.122 0.106 0.025 0.442 - - 0.076 
2016 0.105 0.024 - 0.104 0.107 - 0.431 - - 0.048 
2017 0.032 - - 0.126 0.111 - 0.383 - - - 
2018 - - 0.97 0.102 0.088 0.094 0.392 - - - 
2019 0.070 - - 0.136 0.091 0.090 0.244 - - 0.021 
2020 0.077 - - 0.133 0.093 0.123 0.135 - - 0.025 

  



 

22 

Table 9. Catches per unit of effort (kg per tow for a 1-m-wide dredge) estimated using logbook data, by 
fishing area of the Arctic surfclam commercial fishery by fishing area and year. 

Year 
Fishing area 

1A 1B 2 3A 3B 4A 4B 4C 5A 5B 
1993 - - - - 87.6 84.8 - - - - 
1994 - - - 45.1 96.6 93.4 - - - 101.4 
1995 - 62.6 - 57.9 97.4 94.1 - - - 94.8 
1996 96.8 69.2 - 60.5 120.0 114.6 - - - 57.8 
1997 - 83.2 - - 138.7 62.8 - - - 75.7 
1998 54.0 73.2 - 59.4 - 107.3 66.7 - - 75.8 
1999 136.9 78.5 96.4 74.0 122.4 154.0 - - - 23.0 
2000 95.0 80.8 84.8 70.4 144.0 142.6 - - - 46.5 
2001 97.8 81.7 102.8 73.6 142.4 172.4 - - - 39.7 
2002 90.7 37.4 106.5 79.8 121.3 167.7 141.3 - - 54.6 
2003 104.5 32.1 76.7 77.0 113.4 160.4 135.3 - 41.7 62.9 
2004 137.8 80.0 76.6 86.6 153.1 158.1 142.0 - 60.2 - 
2005 158.1 93.0 110.1 73.0 156.9 153.3 130.3 - - 53.3 
2006 146.8 31.9 84.5 86.8 150.1 155.5 96.7 - - 55.7 
2007 134.3 50.2 97.8 100.6 111.7 179.0 82.7 - - 55.5 
2008 120.9 - 136.2 105.7 149.7 178.9 98.4 58.8 - 58.4 
2009 157.5 132.3 128.0 103.4 182.9 172.4 124.6 - - - 
2010 145.8 144.5 104.2 89.2 173.0 150.0 106.7 - - 38.5 
2011 147.5 113.5 - 75.7 169.1 150.9 119.2 - - 58.4 
2012 133.7 95.3 - 100.6 150.5 130.8 108.5 - - 48.4 
2013 122.3 - 43.5 60.0 78.3 134.7 96.8 - - 58.0 
2014 - - 47.6 73.3 107.5 157.4 108.6 - - 57.7 
2015 100.0 94.2 - 75.8 99.6 167.3 96.9 - - 57.3 
2016 86.5 67.2 - 88.3 99.9 - 97.0 - - 50.3 
2017 73.3 - - 73.2 97.0 - 106.6 - - - 
2018 - - 31.7 90.4 122.3 112.1 90.4 - - - 
2019 132.2 - - 72.5 118.5 165.9 100.5 - - 53.9 
2020 109.2 - - 72.8 115.2 162.0 90.5 - - 30.3 

Average 2018-
2020 

120.7 - 31.7 78.6 118.7 146.6 93.8 - - 42.1 

Median 1993-
2019 

122.3 80.0 96.4 75.7 121.8 153.3 106.6 58.8 51.0 56.5 

  



 

23 

Table 10. Area of the beds, number of daily fishing positions available and retained for the beds, and 
areas estimated through the Kernel analysis corresponding to 100% and 95% of the fishing effort, by 
fishing area and bed. 

Fishing 
area Bed Bed surface 

area (km²) 
Positions on 
the bed (n) 

Retained 
positions (n) 

Exploited 
surface area 
100 % (km2) 

Exploited 
surface 

area 95 % 
(km2) 

1A Les Escoumins 0.881 39 24 0.352 0.282 
Forestville 14.828 300 287 7.034 4.355 
Colombier (1A) 1.306 75 54 1.013 0.715 

2 Rivière-Pentecôte 6.797 15 13 0.778 0.502 
Baie-Trinité 3.338 91 89 1.997 1.313 

3A Moisie Ouest 7.326 215 197 3.422 2.281 
Ste-Marguerite 3.149 100 79 2.190 1.480 
Rivière à Bouleau 4.321 5 4 0.106 0.073 

3B Magpie 4.238 2 2 0.025 0.018 
Rivière-au-Tonnère Est 3.650 182 166 3.208 2.245 

4A Longue-Pointe 5.735 568 465 4.698 3.427 
Longue-Pointe Village 4.578 21 19 0.845 0.556 
Longue-Pointe Ouest 6.234 17 9 0.335 0.206 

4B Natashquan 36.565 1210 1097 23.123 15.225 
5B Rochers aux Oiseaux 

(south) 
13.101 241 191 6.487 4.212 

  



 

24 

Table 11. Known area of the beds, area corresponding to 95% of the fishing intensity, total and mean 
fishing effort (area dredged) and mean exploitation rate by bed and fishing area. 

Area Bed Bed surface 
area (km²) 

Exploited 
surface 

area 
Kernel 
95 % 
(km2) 

Fishing effort (km2) 

Exploitation 
rate 2018-
2020 (%) 

Total 
1993-
2020 

Annual 
average 
2018-
2020 

1A 

Les Escoumins 0.881 0.282 0.133 0.003 0.99 
Forestville 14.828 4.355 0.910 0.029 0.66 
Cap Colombier (1A) 1.306 0.715 0.280 0.018 2.47 
TOTAL 17.015 5.351 1.323 0.049 0.92 

1B 

Cap Colombier (1B) 1.032 0.649 0.198 - - 
Pointe à Michel - 0.010 0.012 - - 
Manicouagan 7.075 0.309 0.047 - - 
Baie-Comeau 6.958 2.041 0.433 - - 
TOTAL 15.065 3.009 0.690 - - 

2 

Baie-Trinité Ouest 1.650 - 0.010 - - 
Baie-Trinité Centre 3.338 1.313 0.378 0.031 2.38 
Baie-Trinité Est 9.235 - 0.012 - - 
Rivière Pentecôte 6.797 0.502 0.061 0.001 0.01 2 
Caouis 3.257 0.249 0.028 - - 
Îles de Mai 4.105 1.067 0.103 - - 
TOTAL 28.382 3.131 0.591 0.032 1.03 

3A 

Ste-Marguerite 3.149 1.480 0.379 0.043 2.90 
Sept-Îles 1.174 0.631 0.403 - - 
Caye de l’Est 1 0.883 0.425 0.188 - - 
Rivière Moisie Ouest 7.326 2.281 0.859 0.078 3.44 
Rivière Moisie Est 4.282 - 0.009 - - 
Pointe St-Charles 0.787 - 0.003 - - 
Pointe à la Perche 3.869 - - - - 
Rivière au Bouleau 4.321 0.073 0.012 0.002 0.05 2 
Rivière Manitou 3.639 - 0.001 - - 
TOTAL 28.547 4.464 1.664 0.124 2.77 

3B 

Sheldrake 1.390 0.763 0.134 - - 
Rivière-au-Tonnerre Ouest 3.098  0.027 - - 
Rivière-au-Tonnerre Centre 4.213 1.723 0.521 - - 
Rivière-au-Tonnerre Est 3.650 2.245 0.676 0.089 3.96 
Magpie 4.238 0.018 0.006 0.002 0.042 
TOTAL 16.589 4.749 1.365 0.091 1.91 

4A 

Longue-Pointe Ouest 6.234 0.206 0.067 0.013 0.212 
Longue-Pointe 5.735 3.427 2.278 0.083 2.42 
Longue-Pointe Village 4.578 0.556 0.067 0.007 0.152 
Mingan - - 0.005 - - 
Havre-Saint-Pierre 0.801 - 0.008 - - 
Île Saint-Charles 0.618 - - - - 
TOTAL 17.966 4.190 2.424 0.103 2.46 



 

25 

Area Bed Bed surface 
area (km²) 

Exploited 
surface 

area 
Kernel 
95 % 
(km2) 

Fishing effort (km2) 

Exploitation 
rate 2018-
2020 (%) 

Total 
1993-
2020 

Annual 
average 
2018-
2020 

4B 

Aguanish 7.260 - 0.002 - - 
Natashquan 36.565 15.225 6.840 0.257 1.69 
Natashquan Est 26.126 - 0.021 - - 
TOTAL 69.951 15.225 6.863 0.257 1.69 

4C 
Blanc-Sablon 2.610 - 0.002 - - 
Brador 0.607 - - - - 

TOTAL 3.217 0.000 0.002 - - 

5A 
5A 20.302 - 0.057 - - 
TOTAL 20.302 0.000 0.057 - - 

5B 

Rocher aux Oiseaux 13.101 4.212 1.811 0.015 0.36 
Rocher aux Oiseaux Nord 1.306 - - - - 
5B N-E 0.083 - - - - 
Est Havre-aux-Maisons 118.027 - - - - 
Est Île d’Entrée 214.303 - - - - 
N-O Grosse-Île 97.017 - 0.110 - - 
TOTAL 443.838 4.212 1.921 0.015 0.36 

1 The Sept-Îles bed includes beds, such as Caye de l’Est. 
2 Average exploitation rate calculated with the total area of the bed. 
  



 

26 

Table 12. Annual mean size (mm) at landing of Arctic surfclams, by fishing area and year, estimated by a 
model that takes into account the year and bed. 

Year 
Fishing area 

1A 1B 2 3A 3B 4A 4B 4C 5A 5B 
1993 - - - - - - - - - - 
1994 - - - 109.4 110.7 115.2 - - - 95.5 
1995 - 95.3 109.2 105.7 116.7 115.1 - - - 98.0 
1996 - 93.9 - 104.4 113.5 111.9 - - - 94.9 
1997 - 95.2 - 104.8 113.5 110.9 - - - 96.4 
1998 - 102.2 - 116.2  112.4 - - - 98.9 
1999 - 110.3 - 115.6 111.1 110.9 - - - - 
2000 115.6 107.2 - 119.1 109.2 111.6 - - - 101.6 
2001 110.0 108.3 - 114.1 111.6 110.8 - - - 99.0 
2002 111.6 108.5 114.6 104.2 106.8 113.0 - - - - 
2003 110.6 - 112.6 112.3 115.0 110.2 100.9 - - 102.3 
2004 114.6 104.1 113.0 114.6 110.1 108.5 105.5 - - 101.1 
2005 113.7 - 110.3 111.1 107.4 111.3 103.4 - - 100.8 
2006 113.7 - 115.4 108.1 104.5 106.1 104.1 - - - 
2007 113.9 - 114.3 109.3 110.1 112.8 101.5 - - 101.6 
2008 112.7 - 113.1 109.2 107.6 113.4 102.3 - - - 
2009 109.0 112.7 115.3 117.6 117.5 113.6 100.0 - - - 
2010 118.5 110.1 115.5 112.9 115.2 116.2 107.2 - - - 
2011 117.7 113.3 - 108.8 115.1 116.4 104.6 - - - 
2012 117.6 114.3 - 108.9 112.7 113.8 104.0 - - 97.0 
2013 115.4 - 113.5 110.0 109.3 112.3 105.6 - - 98.7 
2014 - - 112.9 110.9 112.5 107.8 108.5 - - 94.3 
2015 115.7 117.5 - 110.3 109.8 108.2 110.5 - - 100.3 
2016 117.7 112.6 - 110.4 109.9 - 109.4 - - 98.6 
2017 119.0 - - 111.9 109.7 - 109.2 - - - 
2018 - - 114.6 108.7 111.9 113.4 110.2 - - - 
2019 112.6 - - 112.3 112.4 113.5 106.2 - - 100.2 
2020 114.6 - - 110.2 107.6 107.3 107.4 - - - 

Average 2018-2020 113.6 - 114.6 110.4 110.6 111.4 107.9 - - 100.2 
Median 1993-2019 114.3 108.5 113.5 110.3 111.1 112.3 105.5 - - 98.9 

  



 

27 

Table 13. Indicators used in the decision rule to increase the TAC. Indicators in bold mean that they meet 
the conditions for a quota increase. 

Fishing 
area 

Average landing 
2018-2020 

(80 % of TAC, t) 

Average 
CPUE 

2018-2020 
(median, 
kg/tow) 

Average size 
2018-2020 

(median, mm) 

Exploitation 
rate 

2018-2020 
(%) 

Recommended 
quota increase 

1A 51.5 
(64.0) 

120.7 
(122.3) 

113.6 
(114.3) 0.92 No 

1B Not fished between 2018 and 2020 No 

2 8.9 
(43.9) 

31.7 
(96.4) 

114.6 
(113.5) 1.03 No 

3A 83.4 
(68.2) 

78.6 
(75.7) 

110.4 
(110.3) 2.77 Yes 

3B 93.9 
(75.0) 

118.7 
(121.8) 

110.6 
(111.1) 1.91 No 

4A 132.2 
(139.6) 

146.6 
(153.3) 

111.4 
(112.3) 2.46 No 

4B 209.5 
(340.0) 

93.8 
(106.6) 

107.9 
(105.5) 1.69 No 

4C Not fished between 2018 and 2020 No 
5A Not fished between 2018 and 2020 No 

5B 5.4 
(90.4) 

42.1 
(56.5) 

100.2 
(98.9) 0.36 No 

  



 

28 

FIGURES 

 
Figure 1. Mactromeris polynyma (English name: Arctic surfclam, Stimpson’s surfclam; French name: 
mactre de Stimpson) (Bourdages and Goudreau 2012). 

 
Figure 2. Known distribution of Arctic surfclams in Quebec inshore waters based on data collected from 
logbooks, research surveys and exploratory fisheries (Bourdages and Goudreau 2012). 



 

29 

 
Figure 3. Von Bertalanffy growth curves estimated from growth rings on the shells of Arctic surfclams from 
some eastern Canadian beds. 

 
Figure 4. New England hydraulic dredge (Bourdages and Goudreau 2012). 



 

30 

 
Figure 5. Management areas for the Arctic surfclam fishery in Quebec (Bourdages and Goudreau 2012). 

 
Figure 6. Annual Arctic surfclam landings in Quebec by marine region. 



 

31 

 
Figure 7. Annual Arctic surfclam landings in Quebec by fishing area group. 



 

32 

 
Figure 8. Location of known Arctic surfclam beds in Area 1A. 



 

33 

 
Figure 9. Annual Arctic surfclam landings in Area 1A. 

 
Figure 10. Fishing effort in area dredged (km2) and annual exploitation rates in Area 1A. 



 

34 

 
Figure 11. Annual catch per unit effort (± 95% confidence interval) in Area 1A. 

  



 

35 

 
Figure 12. Annual distribution of the size at landing of Arctic surfclams measured by bed in Area 1A. 



 

36 

 
Figure 13. Estimated annual mean size (± 95% confidence interval) at landing of surfclams in Area 1A. 

  



 

37 

 
Figure 14. Intensity of exploitation from 1993 to 2020 in the Les Escoumins (A), Forestville (B) and Cap 
Colombier (C) beds in Area 1A. 



 

38 

 
Figure 15. Annual distribution of fishing effort per 10 seconds of longitude in Area 1A. 

 
Figure 16. Location of known Arctic surfclam beds in Area 1B. 



 

39 

 
Figure 17. Annual Arctic surfclam landings in Area 1B. 

 
Figure 18. Fishing effort in area dredged (km2) and annual exploitation rates in Area 1B. 



 

40 

 
Figure 19. Annual catch per unit effort (± 95% confidence interval) in Area 1B. 

 
Figure 20. Annual distribution of the size at landing of Arctic surfclams measured by bed in Area 1B. 



 

41 

 
Figure 21. Estimated annual mean size (± 95% confidence interval) at landing of surfclams in Area 1B. 

 
Figure 22. Intensity of exploitation from 1993 to 2020 in the Cap Colombier bed in Area 1B. 



 

42 

 
Figure 23. Annual distribution of fishing effort per 10 seconds of longitude in Area 1B. 



 

43 

 
Figure 24. Location of known Arctic surfclam beds in Area 2. 



 

44 

 
Figure 25. Annual Arctic surfclam landings in Area 2. 

 
Figure 26. Fishing effort in area dredged (km2) and annual exploitation rates in Area 2. 



 

45 

 
Figure 27. Annual catch per unit effort (± 95% confidence interval) in Area 2. 



 

46 

 
Figure 28. Annual distribution of size at landing of Arctic surfclams measured by bed in Area 2. 



 

47 

 
Figure 29. Estimated annual mean size (± 95% confidence interval) at landing of surfclams in Area 2. 

 
Figure 30. Intensity of exploitation from 1993 to 2020 in the Baie-Trinité Centre bed in Area 2. 



 

48 

 
Figure 31. Annual distribution of fishing effort per 10 seconds of longitude in Area 2. 

 
Figure 32. Location of known Arctic surfclam beds in Area 3A. 



 

49 

 
Figure 33. Annual Arctic surfclam landings in Area 3A. 

 
Figure 34. Fishing effort in area dredged (km2) and annual exploitation rates in Area 3A. 



 

50 

 
Figure 35. Annual catch per unit effort (± 95% confidence interval) in Area 3A. 



 

51 

 
Figure 36. Annual distribution of the size at landing of Arctic surfclams measured by bed in Area 3A. 



 

52 

 
Figure 37. Estimated annual mean size (± 95% confidence interval) at landing of surfclams in Area 3A. 

  



 

53 

 
Figure 38. Intensity of exploitation from 1993 to 2020 in the Ste-Marguerite (A) and west Moisie River (B) 
beds in Area 3A. 

  



 

54 

 
Figure 39. Annual distribution of fishing effort per 10 seconds of longitude in Area 3A. 

 
Figure 40. Location of known Arctic surfclam beds in Area 3B. 



 

55 

 
Figure 41. Annual Arctic surfclam landings in Area 3B. 

 
Figure 42. Fishing effort in area dredged (km2) and annual exploitation rates in Area 3B. 



 

56 

 
Figure 43. Annual catch per unit effort (± 95% confidence interval) in Area 3B. 



 

57 

 
Figure 44. Annual distribution of the size at landing of Arctic surfclams measured by bed in Area 3B. 



 

58 

 
Figure 45. Estimated annual mean size (± 95% confidence interval) at landing of surfclams in Area 3B. 

 
Figure 46. Intensity of exploitation from 1993 to 2020 in the Rivière-au-Tonnerre Est bed in Area 3B. 



 

59 

 
Figure 47. Annual distribution of fishing effort per 10 seconds of longitude in Area 3B. 

 
Figure 48. Location of known Arctic surfclam beds in Area 4A. 



 

60 

 
Figure 49. Annual Arctic surfclam landings in Area 4A. 

 
Figure 50. Fishing effort in area dredged (km2) and annual exploitation rates in Area 4A. 



 

61 

 
Figure 51. Annual catch per unit effort (± 95% confidence interval) in Area 4A. 



 

62 

 
Figure 52. Annual distribution of the size at landing of Arctic surfclams measured by bed in Area 4A. 



 

63 

 
Figure 53. Estimated annual mean size (± 95% confidence interval) at landing of surfclams in Area 4A. 

 
Figure 54. Intensity of exploitation from 1993 to 2020 in the Longue-Pointe-de-Mingan bed in Area 4A. 

  



 

64 

 
Figure 55. Annual distribution of fishing effort per 10 seconds of longitude in Area 4A. 

 
Figure 56. Location of known Arctic surfclam beds in Area 4B. 



 

65 

 
Figure 57. Annual Arctic surfclam landings in Area 4B. 

 
Figure 58. Fishing effort in area dredged (km2) and annual exploitation rates in Area 4B. 



 

66 

 
Figure 59. Annual catch per unit effort (± 95% confidence interval) in Area 4B. 

 
Figure 60. Annual distribution of the size at landing of Arctic surfclams measured by bed in Area 4B. 



 

67 

 
Figure 61. Estimated annual mean size (± 95% confidence interval) at landing of surfclams in Area 4B. 

 
Figure 62. Intensity of exploitation from 1993 to 2020 in the Natashquan bed in Area 4B. 



 

68 

 
Figure 63. Annual distribution of fishing effort per 10 seconds of longitude in Area 4B. 

 
Figure 64. Location of known Arctic surfclam beds in Area 4C. 



 

69 

 
Figure 65. Location of known Arctic surfclam beds in areas 5A and 5B. 

 
Figure 66. Annual Arctic surfclam landings in Area 5B. 



 

70 

 
Figure 67. Fishing effort in area dredged (km2) and annual exploitation rates in Area 5B. 

 
Figure 68. Annual catch per unit effort (± 95% confidence interval) in Area 5B. 



 

71 

 
Figure 69. Annual distribution of the size at landing of Arctic surfclams measured by bed in Area 5B. 

 
Figure 70. Estimated annual mean size (± 95% confidence interval) at landing of surfclams in Area 5B. 



 

72 

 
Figure 71. Intensity of exploitation from 1993 to 2020 in the Rocher aux Oiseaux bed in Area 5B. 

 
Figure 72. Annual distribution of fishing effort per 10 seconds of longitude in Area 5B. 



 

73 

 
Figure 73. Landings and total allowable catch (TAC) by fishing area. 



 

74 

 
Figure 74. Catches per unit effort (kg per tow for a 1-m-wide dredge) estimated using logbook data of the 
commercial fishery, by fishing area and by year. The colour code represents the value of the anomaly that 
corresponds to the difference between the CPUE in a given year and the mean CPUE in the time series 
for each fishing area divided by the standard deviation of this mean. 


	ABSTRACT
	INTRODUCTION
	ARCTIC SURFCLAM DISTRIBUTION AND BIOLOGY
	DISTRIBUTION
	GROWTH
	REPRODUCTION

	DESCRIPTION OF THE FISHERY
	FISHERY MANAGEMENT
	CONSERVATION APPROACH

	DATA SOURCE AND ANALYSES
	COMMERCIAL FISHERY DATA
	Landings
	Fishing effort
	Catch per unit effort
	Exploitation rate indicator

	COMMERCIAL SAMPLING
	RESEARCH SURVEYS

	ASSESSMENT OF THE RESOURCE STATUS
	REVIEW OF INDICATORS
	Decision rules

	ECOSYSTEM CONSIDERATIONS
	Habitat
	Species present


	CONCLUSION
	REFERENCES CITED
	TABLES
	FIGURES