Sentinel Surveys 1995-2020 – Catch rates and biological information on Atlantic Cod (Gadus morhua) in NAFO Divisions 2J3KL

Abstract

Catch rates and biological information of Atlantic Cod (Gadus morhua) from the Sentinel gillnet and linetrawl surveys in Northwest Atlantic Fisheries Organization (NAFO) Divisions (Divs.) 2J3KL are updated for 2020. Catch rates for all gears were considerably variable among communities. Catch rates were relatively low and stable in most communities from the North stratum prior to 2005. In contrast, catch rates from the communities located in the South stratum were higher at the beginning of the time-series, and then declined by ten-fold in the mid 2000s. In the Central stratum, catch rates for most communities remained relatively high throughout the time-series. Catch rates increased steadily in communities from the North stratum since the mid 2000s and were relatively high thereafter but remained stable at low levels in the communities from the South stratum during the same period. Similar patterns were observed in catch rates from the small mesh gillnet (all strata) and linetrawl (Central and South strata) surveys. Standardized age-disaggregated catch rate for large mesh gillnet was higher at the beginning of the time-series, peaking in 1998 and dominated by 5–8 year-old fish. Catch rates declined rapidly to the lowest estimate in 2002, then increased during most of the 2003–14 period, before declining once more in the following years. In the case of small mesh gillnet (experimental sites), catch rate declined from 1996 to 2001, then fluctuated during 2002–16, before declining by 50% or more in 2017–20. Most fish caught were 3–7 year-old until 2015, but the contribution of younger year-classes, notably 3 and 4 year-old fish, was reduced thereafter. Large mesh gillnet and linetrawl surveys captured larger fish from specific size ranges, whereas the small mesh gillnet survey retained small and large fish from multiple length-classes. Indices of physiological condition for both male and female cod (Fulton’s condition factor, Hepatosomatic Index, and Gonadosomatic Index) varied seasonally and annually. Total removals (control plus experimental sites, all gears combined) of Atlantic Cod caught in Divs. 2J3KL Sentinel surveys (1995–2020) peaked at 388 t in 1998, declined to 92 t in 2003, reached 270 t annually over 2012–15, and then declined thereafter, reaching 71 t in 2020. Several fish species were recorded as Sentinel bycatch in 2005–20, American Plaice and Winter Flounder were the most common in large mesh gillnet survey.