Research Document 2020/062
2018 Evaluation of Northwest Atlantic Fisheries Organization (NAFO) Divisions 4VWX Herring
By Singh, R., Knox, D., MacIntyre, A., and Melvin, G.D.
Abstract
The 2018 evaluation of the Northwest Atlantic Fisheries Organization (NAFO) Divisions 4VWX Herring considered the data from the 2014–2015, 2015–2016 and 2016–2017 quota years. Quota landings of Atlantic Herring (Clupea harengus) in 2014–2015 were 49,204 tonne (t) and in 2015–2016 were 50,012 t against a Total Allowable Catch (TAC) of 50,000 t for each quota year for the Southwest Nova Scotia/Bay of Fundy (SWNS/BoF) component. In the 2016–2017 quota year, landings were 39,430 t against a TAC of 42,500 t. In 2015, the Spawning Stock Biomass (SSB) estimate was 462,241 t, which decreased in 2016 to 328,253 t and increased to 393,396t in 2017. A survey on 2017 German Bank was initially excluded because it was nine days after the previous one; however, this resulted in a 28-day gap before the next acceptable survey. Subesquently, at the assessment meeting, this survey was included. In 2017, the SWNS/BoF stock component biomass estimate was 11% below the long-term average. It is evident that fluctuations in the biomass estimates are occurring both in Scots Bay and German Bank. In 2015, the fishery catch at age composition by number was comprised of 40% fish at age 2, 15% fish at age 3, 14% at age 4, and 31% at ages 5+. In 2016, the fishery catch at age composition by number was comprised of 27% fish at age 2, 38% at age 3, 10% at age 4, and 25% at ages 5+. In 2017, the fishery catch at age composition by number was comprised of 15% fish at age 2, 33% at age 3, 30% at age 4, and 21% at ages 5+. The proportion of the catch age 5+ has decreased from the 2013 high of 35%.
Landings from the Offshore Scotian Shelf banks improved from the historical low of 58 t in 2014 to 1,803 t (2015), decreased to 1,035 t (2016), and then increased to 3,955 t (2017). There were only limited landings of Herring from the bottom trawl and mid-water trawl gear in the Offshore Scotian Shelf banks areas. No acoustic survey was completed for the offshore area during 2015–2017. Herring abundance in the summer bottom trawl research vessel survey remained relatively constant between 2011 and 2014 and has trended upwards since then. The overall 4VWX area showed an increase in abundance by number in the last three years. This survey has not been considered indicative of overall abundance due to changes in catchability for Herring and a lack of year-class tracking.
The recorded landings in the gillnet and trap net fisheries along the coast of Nova Scotia increased from 4,760 t (2014) to 5,166 t (2015), 7,780 t (2016) and to 7,816 t (2017). In the Little Hope/Port Mouton area, there was substantial increase in the surveyed acoustic biomass in 2015 to a historic high of 145,396 t from 46,077 t in 2014. The surveyed biomass decreased to 61,408 t in 2016 and increased to 66,815 t in 2017, which is below the five-year average of 78,845 t. There was a substantial increase in the surveyed acoustic biomass in the Halifax/Eastern Shore area from 9,586 t (2014) to 68,562 t (2015), followed by a decrease to 54,312 t. The biomass estimate increased to 58,681 t in 2017, which is above both the five-year average (39,602 t) and the long-term average (33,606 t). No survey was completed near Glace Bay during the reporting period (2015–2017). Minimal landings of 4 t were reported in 2016 with no reports of landings in 2015 and 2017. No Herring surveys took place in the Bras d’Or Lakes.
Landings in the New Brunswick weir and shut-off fishery were decreased to a historic low of 146 t in 2015. Landings increased to 4,060 t in 2016 and then decreased to 2,102 t in 2017. In 2007, landings were 30,944 t, the highest in 20 years. The age distribution of fish caught in the New Brunswick weir and shutoff fishery were primarily juveniles, with 99% (2015), 84% (2016) and 58% (2017) by numbers at either age 1 or age 2. There were more older fish caught in the weirs in 2017 which is a departure from what was being caught in the recent years. The success of this passive trap fishery has been historically unpredictable and landings have declined markedly from the 1980s to present. Landings may not be indicative of abundance because catches are extremely susceptible to many factors in addition to abundance, including effort.
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