Science Advisory Report 2018/036

Assessment of the West Coast of Newfoundland (division 4R) herring stocks in 2017

Summary

• Based on preliminary data, herring catches from the West coast of Newfoundland (NAFO Division 4R) totalled 19,938 t in 2016 and 15,194 t in 2017 with an annual total allowable catch of 20,000 t. The quotas allocated to large and small seiners, as well as fixed gears, were not reached in 2017.
• Fall-spawning West coast of Newfoundland herring aged 11+ dominate catches since 2014. The 2008 cohort has been contributing to the fishery, but is not as dominant as the 2000 year-class.
• Catches of the spring-spawning stock have increased slightly in 2017 and have been mostly made up of the 2012 and 2013 cohorts.
• Both of these stocks show a downward trend in mean length-at-age and weight-at-age since the beginning of the 1980s. Since 2011, the condition index of the two stocks is below the series’ average.
• The mean fork length at which 50% of individuals are mature (L₅₀), calculated with data from 1982 to 2017, is respectively 24.1 cm and 25.0 cm for spring spawners and fall spawners. Even though the L₅₀ values varied over the years, recent values are just over their respective averages.
• According to the fall 2017 acoustic survey, fall-spawning herring represent 90% of total abundance of herring.
• Biomass of fall-spawning herring, as estimated from the acoustic survey, has dropped by 63% since 2011, falling to 45,313 t in 2017. Such a low level has not been estimated for this stock since the 1990s.
• For spring-spawning herring, the acoustic index of total biomass is estimated at 5,050 t, which is one of the lowest values of the series.
• A Virtual Population Analysis (VPA) of spring and fall-spawning stocks contains uncertainties on the absolute level of biomass of spawners. The VPA follows the acoustic index, which also suggests that the spawning stock biomass of spring-spawning herring has been very low in recent years and under the limit reference point (LRP = 37,384 t). The spawning stock biomass of fall-spawning herring has been declining for many years and is getting close to the upper reference point (URP = 61,07  t) established in 2010.
• Since old fish from the fall spawning stock that supported the fishery in recent years have declined and recruitment is apparently very weak, maintaining the current level of catches could bring the stock below the upper reference point in the short term.
• Given that the spring-spawning stock is still in the critical zone, it would be advisable to maintain a low level of fishing mortality.

This Science Advisory Report is from the May 2, 2018 Assessment of the West Coast of Newfoundland (Division 4R) herring stocks in 2017. 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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