Science Advisory Report 2021/005
Assessment of the West Coast of Newfoundland (NAFO Division 4R) Herring Stock Assessment in 2019
- Based on preliminary data, herring catches from the West coast of Newfoundland (NAFO Division 4R) totalled 7,418 t in 2018 and 15,806 t in 2019, with an annual total allowable catch of 20,000 t. The fishery experienced difficulties due to weather, changes in herring distribution and management measures.
- The proportion of landings composed of the spring-spawning stock have increased from 2.3 % in 2014 to 30.0 % in 2019. Catches of spring-spawning herring were dominated by the 2013 cohort.
- Fall spawning herring age 11+ dominate the landings since 2014. The 2008 cohort contributed to the fishery in recent years, but was not as dominant as the 2000 year-class.
- Both of these stocks show a general downward trend in mean weight-at-age for ages 3+ herring since the beginning of the 1980s, and a downward trend in condition since early 2000s. Relative condition factors were well predicted by zooplankton indices.
- Evidence from scientific sampling and the fishery indicates the presence of young fish in recent years.
- The 2019 fall acoustic survey estimated 47,522 t and 68,796 t of spring and fall spawning herring, respectively. There is evidence of changes in catchability of the acoustic survey in recent years indicating that the survey may not consistently provide a reliable index of abundance.
- Further investigation of the assessment model used as the basis of the advice confirmed existing concerns over model sensitivity to time-varying survey catchability and other input assumptions (constant natural mortality) and model’s inability to reliably estimate recruitment. As a result, the model was rejected as the basis of the advice. A review of the assessment framework for 4R herring is recommended.
- The available evidence up to 2019 (commercial catch-at-age, age and length at maturity, abundance of young fish, low exploitation rate in 2019) indicate that current harvest levels do not pose significant risk to herring stocks in 4R in the short term. This conclusion should be revisited following a review of the assessment framework.
This Science Advisory Report is from the November 18-20, 2020 regional advisory meeting on the Assessment of the West Coast of Newfoundland (NAFO Division 4R) herring (Clupea harengus) stocks in 2020. 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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