Research Document 2023/076

Assessment of Capelin (Mallotus villosus) in 2J3KL to 2019

By Mowbray, F.K., Adamack, A.T., Murphy, H.M., Lewis, K., and Koen-Alonso, M.

Abstract

The assessment of the 2J3KL Capelin (Mallotus villosus) stock included fisheries and ecosystem data to the fall of 2019, and the sea ice data available to March 2020. Data sources reviewed included spring 3L acoustic surveys, inshore larval surveys, multispecies bottom trawl surveys and fishery catches, state of the ecosystem, predatory fish diets and consumption of Capelin by fishes. Following the collapse of this stock in the early 1990s, the spring acoustic survey abundance index declined by an order of magnitude. Coincidentally the size at age of younger Capelin increased and the age at maturity decreased. There have been no strong indications of recovery of the stock since. The 2019 spring acoustic abundance index was at a similar level to 2017 and was consistent with values observed during the period of lowest values during the early 2000s. Age-3 fish comprised a larger than usual portion of the spring survey abundance and fishery catches in 2019. Patterns in Capelin distribution, growth and maturation were consistent with the interpretation that the surveyed cohorts were weak (2018) to moderate (2017) in strength. Due to the high proportion of maturing age-2 fish and the usual high rates of post-spawning mortality few age-3 spawners are expected in 2020. The larval index has indicated poor production for the last 5 years including the two cohorts entering the fishery in 2020. However fewer empty stomachs in adults suggests that feeding success has improved moderately in the last 3-4 years, which may lead to an improvement in post larval survival. The forecast model predicts that Capelin biomass index for the 2020 spring acoustic survey will likely decline compared to 2019, returning to low biomass levels similar to that seen in 2017. The increases in groundfish observed in the late-2000s and early-2010s appear associated with bottom-up processes, including an improved prey field, with modest increases in Capelin availability in comparison with the 1990s. Capelin and shrimp are key forage species in the ecosystem. More recent declines in total finfish biomass may be associated with simultaneous reductions in Capelin and shrimp availability.

Research Document 2023/076 (PDF, 3,257 KB)

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