Newfoundland and Labrador Comparative Fishing Analysis – Part II

Abstract

An extension of the Newfoundland and Labrador (NL) comparative fishing program was undertaken in 2023, expanding coverage and addressing data gaps in the 2021–22 comparative program. Results presented here must be considered alongside those reported during Newfoundland & Labrador Comparative Fishing Analysis – Part I. Comparative fishing in the spring of 2023 between the Canadian Coast Guard Ship (CCGS) Teleost and CCGS John Cabot indicated that conversion factors are required for Div. 3LNO for 12 taxa, including two with significant length effects. Thirty four taxa showed no significant difference in relative catchability, and three evaluated taxa had insufficient data to determine if a conversion factor is appropriate. Deep water (>750 m) comparative fishing in the fall of 2023 supported the estimation of conversion factors for the fall CCGS Teleost survey series for seven taxa, including one (Greenland Halibut) which showed a significant length effect. Sixteen taxa showed no significant difference in relative catchability. A re-evaluation of some taxa groupings, following a recommendation from Part I, led to the additional estimation of eight conversion factors for the CCGS Teleost and nine for the CCGS Alfred Needler in fall. Two re-evaluated groupings for the Teleost fall had insufficient data to determine if a conversion factor is appropriate. To support community-level analyses, conversion factors were estimated for functional groups on an Ecosystem Production Unit scale and for Division (Div.) 2J3KL. Consistent with single-species analyses, coverage and sample size were insufficient to estimate conversion factors in Subdivision (Subdiv.) 3Ps or for the CCGS Alfred Needler on the Grand Bank (Div. 3LNO). Conversion factors are specific to the area, season and species, taxa, or functional group for which they have been estimated, and are not interchangeable between the CCGS Alfred Needler and CCGS Teleost. The CCGS Teleost and CCGS Alfred Needler have been used interchangeably in the NL multispecies surveys, with catchability previously assumed to be equal. Though no direct comparisons of catchability were performed, trawl performance and geometry, and variation in conversion factors estimated for each of these vessels relative to the new Offshore Fishery Science Vessels (OFSVs) indicate differing catchability.