Research Document 2024/019
Sentinel Surveys 1995–2018 – Catch Rates and Biological Information on Atlantic Cod (Gadus morhua) in NAFO Divisions 2J3KL
By Mello, L.G.S., Simpson, M.R., and Maddock Parsons, D.
Abstract
Catch rates and biological information of Atlantic Cod from the Sentinel survey program in Northwest Atlantic Fisheries Organization (NAFO) Divisions (Divs.) 2J3KL are updated for 2018. Temporal trends in gillnet (3¼ and 5½ inch mesh) and linetrawl unstandardized catch rates were initially similar for all gears, with relatively high values at the beginning of each time-series, followed by sharp declines in the late-1990s, early-2000s. Catch rates for small mesh gillnet and linetrawl oscillated around or below the historical mean catch rate thereafter, and increased for large mesh gillnet until 2014–15. Catch rates for all gears declined since then. Mean catch rate for small mesh gillnet was consistently higher than that of large mesh gillnet for most of the time-series.
Standardized age-disaggregated catch rate for large mesh gillnet in the Northern area was stable at low levels in 1995–2004 (mostly ≥6 year-old fish), then increased rapidly and peaked in 2015 before declining over 2016–17. The contribution of ≤7 year-old fish increased considerably since 2012. Catch rates in the Central area were higher at the beginning of the time-series (mostly 6–8 year-old fish), declined rapidly to their lowest values in 2002, and then followed a pattern similar to that of the Northern area. Catch rates in the Southern area declined rapidly over 1998–2002, then remained stable at low levels. Catch rates for small mesh gillnet in Northern and Central areas indicated patterns similar to those of large mesh size gillnet. In the Southern area, catch rates declined until 2014, then increased by several folds over 2015–16. Temporal trend for linetrawl (Central area) was also similar to those of gillnets in Northern and Central areas (mostly 3–8 year-old fish). Three to five year-old fish were well-represented in 1995–2008, but declined thereafter. Age-aggregated catch rates showed patterns similar to those of age-disaggregated estimates in all cases.
Large mesh gillnet and linetrawl captured larger fish from specific size ranges; whereas the small mesh gillnet retaining small and large fish from multiple length-classes. Indices of physiological condition for both males and females 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 (1995–2017) peaked at 388 t in 1998, declined to 92 t in 2003, reached 270 t annually over 2012–15, and then declined to 173 t in 2017. Several fish species were recorded as Sentinel bycatch in 1995–2017: American Plaice and Winter Flounder were the most common in large mesh gillnet.
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