Science Advisory Report 2017/028

Assessment of Newfoundland east and south coast herring to the spring of 2016

Summary

Overview

• The spring research gillnet program was used to update the stock status index in Bonavista Bay-Trinity Bay and Fortune Bay. The group was only able to provide advice for St. Mary’s Bay-Placentia Bay because of an opportunistic acoustic survey in 2016.
• Given the absence of a quantitative indicator to evaluate stock trajectory, the group was unable to provide advice on stock status for White Bay-Notre Dame Bay or Conception Bay-Southern Shore.

Biological and Ecological Information

• Since 2010, large-scale ocean colour imagery over the northwest Atlantic, from the southern Grand Bank to northern Labrador, indicates later onset in peak timing and reduced duration of the spring phytoplankton bloom compared to normal conditions.
• Following a period of above average values, a composite index of climate conditions throughout the region fell below average in 2014-15, returning to above average in 2016.
• Herring spawning stock composition changed in the early 2000s from spring spawner to fall spawner dominance in all stock areas except Fortune Bay. These changes are potentially correlated with environmental indicators.
• In 2015 a broad age distribution with multiple year classes above the long term mean was observed in all stock areas except Fortune Bay.
• The length at 50% maturity (L50) decreased through the late 1980s and 1990s, but showed a general increasing trend since 1996. The average L50 of spring spawners in the commercial fishery from 2010 to 2015 was 246 mm and for fall spawners was 255 mm (fork length).
• The size at age decreased in all stock areas in the 1990s but has remained stable since the 2000s.
• While Harp Seal abundance has been stable at a high level since the mid-late 2000s, total finfish biomass in the Newfoundland and Labrador shelves bioregion increased from the mid-2000s to early 2010s, then leveled off, and over the last couple of years is showing signs of decline, especially in southern areas (3LNO and 3Ps). This coincides with a joint reduced availability of capelin and shrimp in the offshore since 2014. Consequently there is a potential for increased predation pressure on herring, particularly if predators increase their foraging/residence in inshore waters.

White Bay – Notre Dame Bay

• Without a fishery-independent index of abundance (i.e. acoustic survey or research gillnet program), the status of this stock could not be assessed. Biological updates were provided based on samples collected from the commercial fishery.
• Landings increased over the past three years and industry reports that effort has been consistent over that time period. Preliminary data indicate that at least 65% of the TAC was taken in 2016, the highest landings since the mid-1990s.
• The 2008 year class continued to dominate the 2014 catch; in 2015 age 2 spring spawners comprised an unusually large proportion of the catch - however this is based on a small sample size. Fall spawners comprised 68% of the 2015 catch.
• Purse and tuck seine fishers indicated increasing abundance in 2015, gillnet fishers indicated increasing abundance from 2011 to 2014 but a decrease in 2015.

Bonavista Bay – Trinity Bay

• The stock status index derived from the research gillnet program had an increasing trend over the past five years and the 2014 and 2015 values are among the highest in the time series. The evaluation of current stock status is positive.
• Short term prospects for the stock are positive, with mean catch rates of age 4-6 herring of both spawning components increasing over the past several years.
• Landings in 2015 were at the highest level since 1990s, and 73% of TAC was taken. Preliminary data indicates landings were down slightly in 2016.
• Overall there was a broad age distribution in the commercial catch, however the 2008 fall year class continued to dominate in 2014 and 2015. Fall spawners comprised 80% of landings in both years.
• Purse and tuck seine fishers indicated increasing abundance from 2010 to 2015, gillnet fishers indicated increasing abundance from 2011 to 2015.
• Combined catch rates in the spring research gillnet program generally increased from 2010 to 2015, reaching the second highest level in the time series. Catch rates declined dramatically in 2016, and fishers indicated this was due to the late arrival of herring in the spring. There is a broad age structure in the research gillnet program, however the 2008 fall year class dominates the catch.
• Recruitment of age 4 fish in the research gillnet program in 2015 was high for fall spawners and average for spring spawners.

Conception Bay – Southern Shore

• Without a fishery-independent index of abundance (i.e. acoustic survey or research gillnet program), the status of this stock could not be assessed. Biological updates were provided based on samples collected from the commercial fishery.
• After a period of low fishing activity, participation and landings have generally increased in this stock area over the past four years; 20% of the TAC was taken in 2015 and preliminary data indicates landings were higher in 2016. All commercial landings were in Conception Bay.
• The age distribution in the commercial fishery was dominated by the 2008 fall year class with a broad distribution in 2015; fall spawners accounted for 73% of the catch.
• All fleets indicated that abundance in the area increased from 2014 to 2015.

St. Mary’s Bay – Placentia Bay

• An opportunistic acoustic survey was conducted in February 2016 in Placentia Bay, providing an estimate of relative abundance; however without acoustic surveys or the research gillnet program, it will not be possible to update the status of this stock going forward.
• The acoustic survey indicated that biomass in Placentia Bay was slightly below the mean of the acoustic surveys conducted between 1986 and 2000. Based on these results the overall evaluation of the current stock status is positive.
• After a period of no purse seine fishing activity, landings in Placentia Bay have increased over the past five years. In 2015, 16% of the TAC was taken and preliminary data indicates 25% was landed in 2016.
• In 2015, commercial samples were largely composed of age 11+ fish with 95% fall spawners, however this was based on a small sample size. The age distribution of bait samples taken at the same time was broader, with 59% fall spawners.
• Purse seine fishers indicated an increase in abundance from 2013 to 2015. Gillnet fishers indicated a decrease in abundance from 2012 to 2015.

Fortune Bay

• Spring spawners comprise over 85% of the catch in Fortune Bay. Fall spawners do not occur in adequate numbers to allow evaluation of this spawning component.
• The stock status index derived from the spring research gillnet program has had a declining trend since 2010. The evaluation of current stock status is negative.
• Future prospects based on the catch rate of age 4-6 herring are poor.
• Landings and TAC have been decreasing since 2006, and only 11% of the TAC was landed in 2016.
• The age distribution of the commercial catch continued to be highly skewed toward older fish, with over 80% of the catch consisting of age 11+ spring spawners in 2014 and 2015.
• Gillnet fishers indicated declining abundance from 2001 to 2015. Bar seiners indicated increasing abundance since being included in the survey in 2013.
• Combined catch rates in the spring research gillnet program have been well below the time series average since 2011. The age distribution has been highly skewed toward age 11+ spring spawners since 2013. In 2016, age 4 and 11+ spring spawners each accounted for 40% of the catch.
• Recruitment of age 4 herring was extremely poor from 2003-15; recruitment in 2016 was above average.

This Science Advisory Report is from the January 31 to February 1, 2017 Status of Divisions 3KL and Subdivision 3Ps Herring meeting in St. John’s, NL. Additional publications from this meeting will be posted on the Fisheries and Oceans Canada (DFO) Science Advisory Schedule as they become available.

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