Science Advisory Report 2022/050

2022 Assessment of 4VWX Herring

Summary

Southwest Nova Scotia/Bay of Fundy Spawning Component

• Landings were 34,159 t in 2020 and 32,629 t in 2021, and the fisheries did not exceed the Total Allowable Catch (TAC) of 35,000 t for each year for the SWNS/BoF component.
• Although there is uncertainty with annual estimates of spawning stock biomass (SSB), there is a decreasing trend in the acoustic index since 1999 to present that is evident for the two remaining major spawning grounds, German Bank and Scots Bay, which are used to assess the relative stock status of the SWNS/BoF component.
• Since 2018, the three-year moving average acoustic index of SSB from Scots Bay and German Bank, that is used to determine stock status, has been below the Limit Reference Point (LRP). The SWNS/BoF stock is in the Critical zone according to DFO’s Precautionary Approach (PA) policy. The PA policy requires that exploitation be kept at the lowest possible level until the stock is considered to be out of the Critical zone.
• For every surveyed spawning ground (Scots Bay, German Bank, Trinity Ledge, Spectacle Buoy and Seal Island), spawning biomass is from 16–48% less than the 1999–2021 average biomass.
• Trinity Ledge and Seal Island were historical major spawning grounds and have not recovered.
• The age structure observed in the commercial catch indicates that the conservation objective to maintain a broad range of ages is generally being met. Industry-developed management measures that limit exploitation on juvenile fish and spawning grounds are important for sustainability. Management procedures with different selectivity for small fish were evaluated in the MSE framework. Under assumptions used in the MSE operating models, there is evidence that limiting removals of small fish can increase productivity of the stock but not to the extent that was conventionally considered.
• Since the 1970s, mean weight-at-age for Ages 4–11 has been declining and mean weight-at-age for Ages 1 and 2 has been increasing. The mechanisms influencing changes in weight-at-age for the SWNS/BoF component Herring are not well understood and require further study.

Offshore Scotian Shelf Banks

• Since 1996, a fishery has occurred on aggregations on the offshore banks, primarily in May and June, with catches ranging from 20,261 t in 1997 to 37 t in 2020. Landings have been low, far less than the 12,000 t annual allocation, since 2012. Landings from the offshore are subject to market, weather, and fish availability.
• No acoustic surveys were conducted on the Offshore Scotian Shelf during the years 2015–2021.
• In the absence of recent information about stock status, there is no basis for evaluating whether the current 12,000 t catch allocation is appropriate.

Coastal (South Shore, Eastern Shore and Cape Breton) Nova Scotia

• From 2012 to 2021, landings in the Little Hope/Port Mouton area have ranged between 2,150 t and 10,747 t, and have been near or slightly above the allocation.
• From 2012 to 2021, landings in the Eastern Shore area have ranged between 771 t and 6,871 t, and have been within the allocation.
• Landings were minimal for Glace Bay, between 0 t to 9 t annually, since 2018.
• The Bras d’Or Lakes area remains closed to Herring fishing. It has been noted since 1997 that the status of Herring in the Bras d’Or Lakes is cause for concern. In the absence of current abundance information, there is no basis for provision of Science advice on appropriate catch levels for the Bras d’Or Lakes.
• Individual spawning groups within the Coastal component are considered vulnerable to fishing because of their relatively small size (biomass) and proximity to shore. For this reason, a large effort increase in new areas has a potential to markedly reduce abundance, with limited tracking of information about the status of the individual spawning groups.
• With the exception of the four main spawning areas, the biomass of various additional spawning groups and landings from these groups are poorly documented. In addition to the traditional bait and personal-use fisheries, directed roe fisheries have occurred on several spawning grounds since 1996.

Southwest New Brunswick Migrant Juvenile

• The southwest New Brunswick (NB) weir and shutoff fisheries have relied, for over a century, on the aggregation of juvenile Herring (Ages 1–3) near shore at the mouth of the Bay of Fundy.
• The landings in this fishery are usually juveniles (Age 1 or 2), as observed in 2020 and 2021; however, the catch consisted of 55% Age 3 fish in 2019.

• NB weir landings are currently at, or near, the lowest observed values since reporting began in the 1970s. Landings for this fishery are highly variable and are not indicative of abundance because catches are susceptible to market, effort, and fish availability.

Management Procedure Performance and Exceptional Circumstances

• DFO Resource Management has requested DFO Science to use the MSE framework to identify candidate Management Procedures (MPs) that are expected to rebuild the SWNS/BoF component above the LRP with a high probability.
• Of the 11 candidate MPs evaluated, 8 MPs (Nfref, fix12.5, HS_PA_F11.8, HS_PA_F13.1a, P3.5, P3.6a, P3.7_20_80, and STEP1a) had a probability of the Spawning Stock Biomass (SSB) being above the mean SSB from 2005–2010 of at least 75% in each year from years 10–15 of the projection period for each Operating Model (OM) in the reference set of OMs.
• No exceptional circumstances were triggered during the first two projection years of the MSE framework.

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  This Science Advisory Report is from the March 31, 2022, Maritimes Regional peer review of the Stock Assessment of Herring in Northwest Atlantic Fisheries Organization (NAFO) Fishing Areas 4VWX. Additional publications from this meeting will be posted on the Fisheries and Oceans Canada (DFO) Science Advisory Schedule as they become available.

  

  Science Advisory Report 2022/050 (PDF, 1892 KB)

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