Science Advisory Report  2011/046

2011 Assessment of 4VWX Herring

Summary

SW Nova Scotia/Bay of Fundy

• Landings for the 2009/2010 quota year were 45,534t against a Total Allowable Catch (TAC) of 55,000t for the Soutwest Nova Scotia (SWNS)/Bay of Fundy component. Landings have tracked the TAC in recent years, with most of the quota being taken each year since 2002. In 2010, as a result of an industry decision late in the season 9,466t of quota was left in the water. This was in order to avoid catching and adding more fish of a size of less than 23cm to the 2010 landings.
• In 2009, the fishery catch at age composition was comprised of 45% fish by number at 2 years of age and 7% older than age 5. In 2010 there were 60% fish by number at age 2 and only 3% older than age 5 in the catch. Acoustic survey age composition had a broad age distribution of spawning fish with ages 3-11 and 15% older than age 5.
• In 2010, biomass estimates decreased in the main areas for Scots Bay and German Bank to a total of 312kt, which is a decrease of approximately 175kt from 2009 (36% decrease). The amount of spawning fish documented on Trinity Ledge in 2010 was again extremely low.
• There has been a trend of declining mean-weight at age but it was significantly more than would have occurred if the trend continued in 2010. About 10-15% of the observed decline in stock spawning biomass (SSB) from 2009 to 2010 can be attributed to this reduced mean weight at age. This unexpected reduction was consistent with the unusual environmental conditions in 2010. Declining trends in mean-weight at age since the 1970s has reduced productivity of the stock.
• Relative exploitation rate has been constant in response to changes in survey biomass.
• SSB has declined from the average of 551kt to 377kt (32% reduction) for the time periods 2001-2004 to 2005-2010. This assessment indicates stability at the lower level from 2005-2010 and shows little or no signs of improvement.  This lack of rebuilding despite reduced catch levels in recent years is cause for concern.
• Harvest strategy that exercises caution, including additional restrictions in small fish removals, is appropriate.

Offshore Scotian Shelf Banks

• Since 1996, a fishery has taken place on feeding aggregations on the offshore banks of the Scotian Shelf, primarily in May and June, with catches ranging from 1,000 to 20,000t. In 2010, almost the entire allocation was caught with total landings above average at 11,862t
• An industry survey of the offshore Scotian Shelf area was conducted on ‘The Patch’ in June 2010, with 3.5kt of biomass estimated. The industry is again encouraged to explore and undertake further structured surveys of the offshore area in 2011.
• There is minimal new information to add and no reason to change the previous recommendation that the initial catch allocation for 2011 should not exceed 12,000t as described in the DFO management plan.

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

• The landings in the roe gillnet fisheries along the coast of Nova Scotia decreased from 9,783t in 2009 to 5,575t in 2010.
• In 2010 the survey biomass for the Little Hope/Port Mouton area declined to 26.7kt, just above the recent 5 year average of 20.9kt. The survey biomass in the Halifax/Eastern shore area declined to 27.7kt, well below the recent 5 year average of 41.9kt.
• Collaborative research with industry has improved knowledge of three areas (Little Hope/Port Mouton, Halifax/Eastern Shore and Glace Bay), but there has been no increase in knowledge of other areas. It is again recommended that no coastal spawning groups experience a large effort increase in new areas until enough information is available to evaluate the state of that spawning group.
• It has been noted since 1997 that the status of herring in the Bras d’Or Lakes is cause for concern, but there has been no research or surveys in recent years. It is; therefore, appropriate to reiterate that no fishing should take place on this spawning component.
• Harvest levels from these areas use a five year average of recent catches and/or surveyed acoustic biomass with the Calibration Integration Factor (CIF) to set initial targets. It is recommended that the “survey, assess, then fish” protocol should continue to be applied.

SW New Brunswick Migrant Juvenile

• The southwest New Brunswick juvenile herring (ages 1-3) are considered to be a mixture of juveniles, dominated by those originating from Northwest Atlantic Fisheries Organization (NAFO) Subarea 5 spawning components, and have, therefore, been excluded from the SW Nova Scotia/Bay of Fundy quota.
• Landings in the 2010 New Brunswick weir and shut-off fishery were 10,958t, up from the low of 4,031t in the previous year. It is notable that as recently as 2007 landings were 30,944t, the highest in nearly 20 years and higher than the long term average of 23,560t.
• The age distribution of fish caught in the 2010 New Brunswick weir and shutoff fishery were mostly juveniles, which are well suited to the sardine market, with 95% at age 2.
• The number of weirs with catches increased in the 2010 season, but effort (number of active weirs) remained similar.
• The success of this passive fishery is historically unpredictable, and catches are inherently susceptible to many natural variables in addition to abundance.

This Science Advisory Report is from the Fisheries and Oceans Canada, Canadian Science Advisory Secretariat, regional advisory meeting of 7-8 April 2011 on NAFO Divisions 4VWX Herring stock assessments. Additional publications from this process will be posted as they become available on the DFO Science Advisory Schedule.

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