Sentinel Surveys 1995-2021 – Catch rates and biological information on Atlantic Cod (Gadus morhua) in NAFO Subdivision 3Ps

Abstract

Catch rates and biological information of Atlantic Cod (Gadus morhua) from the Sentinel survey in the Northwest Atlantic Fisheries Organization (NAFO) Subdivision 3Ps are updated for 2020, and preliminary results presented for 2021. Temporal trends in gillnet (small 3¼ inch mesh, large 5½ inch mesh) and linetrawl unstandardized catch rates were similar for all gears, with the highest values at the beginning of each time-series, followed by sharp declines after 1997, and oscillating around the series’ mean catch rate thereafter. Age-disaggregated standardized catch rates for large mesh gillnet in recent year-classes were generally weaker than those in the past, but have increased for linetrawl in 2018–20. Age-aggregated catch rates were higher at the beginning of each time-series for both large mesh gillnets and linetrawl, declined over the mid to-late 1990s, then remained at their lowest levels thereafter in the case of large mesh gillnet, but increased in the case of linetrawl in 2018–20. Length frequencies of Atlantic Cod measured in Sentinel surveys indicated that the small mesh gillnet was the least selective gear (retaining small and large fish from multiple length-classes), whereas large mesh gillnet and linetrawl captured larger fish in specific size ranges and few overlapping length-classes. Fish lengths from small mesh gillnet showed several modes ranging between 37–43 cm and 53–60 cm throughout the time-series, while those of fish from large mesh gillnet and linetrawl ranged between 60–68 cm and 42–61 cm, respectively. Indices describing the physiological condition of Atlantic Cod varied at both seasonal and annual scales. Total annual removals of Atlantic Cod by Sentinel harvesters peaked at 38 t (2001), then declined to a minimum of 9.9 t (2016), prior to increasing to 15.4 t in 2020. At least 15 fish species have been recorded as Sentinel bycatch over 2005–20, with American Plaice (Hippoglossoides platessoides) and Redfish (Sebastes sp.) being the most common in gillnet and linetrawl, respectively.