Science Advisory Report 2018/052

2018 Assessment of 4VWX Herring

Summary

SW Nova Scotia/Bay of Fundy

• Landings for the 2014-2015 and 2015-2016 quota years were 49,204t and 50,012t against a Total Allowable Catch (TAC) of 50,000t each year for the SW Nova Scotia/Bay of Fundy component. In the 2016-2017 quota year, landings were 39,430t against a TAC of 42,500t. The quota was reduced in 2017 due to concerns related to the lack of stock rebuilding and decreased acoustic biomass estimates from the main spawning grounds.
• Although there is uncertainty associated with the biomass estimates, longer term trends in biomass appear to be evident for the Southwest Nova Scotia/Bay of Fundy (SWNS/BoF) spawning component: a decreasing trend in the German Bank area from 1999 to present, and an increasing trend in the Scots Bay area since 2005. The last three years on German Bank have been the lowest in the history of the surveys.
• At the March 2013 Assessment Meeting, it was noted that fish abundance could be overestimated (double-counting) or underestimated (missing fish) using the acoustic survey approach employed. Methodology was presented in Melvin et al. (2014) to account for double-counting. These results were used to revise the acoustic Spawning Stock Biomass (SSB ) estimates for the entire time series, including the Limit Reference Point (LRP). Consensus was reached on using these revised estimates as the basis of the assessment and the advice.
• In 2012, an LRP for the SWNS/BoF Herring spawning component (German Bank and Scots Bay) was identified as the 2005-2010 average acoustic survey biomass (371,067t), below which the risk of serious harm is unacceptable (Clark et al. 2012). Revisions to the method for estimating the SSB adopted at this assessment resulted in a change in the LRP from 371,067t to 316,313t.
• The three-year moving average decreased by about 8% in 2017 to be at the LRP for the first time since 2011. Stock biomass and the TAC have been relatively stable at a low level in recent years from (2011 to 2016). The consensus of the meeting was that further management measures that reduce exploitation are required to support stock rebuilding.
• The biomass of spawning fish estimated to be on Trinity Ledge from 2015 to 2016 is low relative to values observed in the early 2000s; however, there was a substantial increase in the SSB in 2017. This is a good sign and may indicate a return of spawning to the area. Additionally, spawning biomass was also recorded in the fall in the Spectacle Buoy area for the first time since 2006. Until there is a sustained increase in the biomass estimate over several years, fishing during the spawning season on Trinity Ledge has the potential to jeopardize the persistence of this spawning unit.
• The broad range of ages 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 and should be continued and strengthened.
• There has been a trend of declining mean weight at age. Declining trends in commercial mean weight at age since the 1970s have reduced productivity of the stock.
• Given that the stock is at the LRP, the importance of a new framework assessment for this stock to address sources of uncertainty and make improvements to the assessment was emphasized.

Offshore Scotian Shelf Banks

• Since 1996, a fishery has occurred on feeding aggregations on the offshore banks, primarily in May and June, with catches ranging from 20,261t in 1997 to 58t in 2014. Landings have been low, less than 10,000t since 2012, averaging less than 2,000t but increased to 4,000t in 2017. Landings from the offshore are subject to market, weather and fish availability.
• No industry surveys were conducted on the Offshore Scotian Shelf during the years 2015-2017.
• In the absence of recent information about stock status there is no basis for evaluating the current 12,000t catch allocation. The industry is encouraged to explore and undertake structured surveys of the offshore area. Coastal (South Shore, Eastern Shore and Cape Breton) Nova Scotia
• From 2009 to 2017, landings in the Little Hope/Port Mouton area have ranged between 2,150t and 5,943t, and have been near or above the allocation in some years (from −1,246t to +1,559t).
• From 2009 to 2017, landings in the Eastern Shore area have ranged between 771t and 6,045t, and are generally within the allocation.
• Landings were minimal for Glace Bay with 4t reported in 2016 and none in 2015 and 2017.
• The Bras d’Or Lakes area remained 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 the Bras d’Or Lakes should remain closed.
• 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 in the absence of information about the status of the specific spawning group.
• With the exception of the four main areas, the size 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 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); however, in 2017 older fish were present the catch. This is a departure from what was being caught during the last decade.
• For the time series presented, current landings are at or near the lowest observed. In 2015 and 2017, the number of weirs with landings was the second lowest recorded (11), but 26 weir reported landings in 2016.
• Abundance of Herring available to the weirs is unknown and there is no research being conducted to investigate local Herring abundance.
• The primary sources of information for assessing this component are the landings, which have declined markedly from the 1980s to present. The landings time series for this fishery may not be indicative of abundance because catches are extremely susceptible to many factors in addition to abundance, including effort.

Upper Stock Reference

• An Upper Stock Reference (USR) of 632,626t for the combined observed acoustic biomass on the spawning grounds of German Bank and Scots Bay was proposed. As no consensus could be reached, it was agreed that no USR recommendation would be put forward from this meeting. This discussion will be revisited at the next stock framework.

This Science Advisory Report is from the April 11-12, 2018, Assessment of 4VWX Herring.  Additional publications from this process will be posted on the Fisheries and Oceans Canada (DFO) Science Advisory Schedule as they become available.

Complete document (PDF, 1,317 KB)

Accessibility Notice

This document is available in PDF format. If the document is not accessible to you, please contact the Secretariat to obtain another appropriate format, such as regular print, large print, Braille or audio version.