Northeast Arctic Cod and Prey Match-Mismatch in a High-Latitude Spring-Bloom System

Frode B Vikebø,Jolynn Carroll,Håvard G Frøysa,Jonas Juselius,Ole Jacob Broch,Clarissa Akemi Kajiya Endo,Øystein Langangen

doi:10.3389/fmars.2021.767191

Abstract

By combining an ocean model, a nutrient-phytoplankton-zooplankton-detritus-model and an individual-based model for early life stages of Northeast Arctic cod we systematically investigate food limitations and growth performance for individual cod larvae drifting along the Norwegian coast from spawning grounds toward nursery areas in the Barents Sea. We hypothesize that there is food shortage for larvae spawned early and late in the 2-monthlong spawning period, and to a larger degree to the north and south of the main spawning grounds in the Lofoten. Model results for three contrasting years (1995, 2001, and 2002) show that spawning early in the season at spawning grounds in the Lofoten and farther north is favorable for larval growth close to their size- and temperature-dependent potential. Still, both early and late spawned larvae experience slower growth than individuals originating closer to the time of peak spawning late March/early April. The reasons are low temperatures and shortage in suitable prey, respectively, and this occurs more frequent in areas of strong currents about 1–2 months post hatching. In particular, late spawned larvae grow relatively slow despite higher temperatures later in the season because they are outgrown by their preferred prey.

Highlights

Life stages of fish experience high mortality rates, associated with a range of potential drivers, that lead to high losses prior to recruitment to the stock (“recruitment-processes”). Hjort’s (1914) seminal work emphasizes the need for first-feeding larvae to match prey immediately after the yolk sac is absorbed (“critical period”) and being transported to favorable nursery grounds (“aberrant drift”)
The smoothing of abundances of nauplii 3 and 4 per grid cell is done by diving the number of nauplii in each grid cell across 5 by 5 grid cells according to a bell-shaped function
North of 66◦N the highest values are found in the core of the Norwegian Coastal Current (NCC) and at the shelf edge, while farther south the C. finmarchicus are spread more out across the shelf

Summary

Introduction

Life stages of fish experience high mortality rates, associated with a range of potential drivers, that lead to high losses prior to recruitment to the stock (“recruitment-processes”). Hjort’s (1914) seminal work emphasizes the need for first-feeding larvae to match prey immediately after the yolk sac is absorbed (“critical period”) and being transported to favorable nursery grounds (“aberrant drift”). Hjort’s (1914) seminal work emphasizes the need for first-feeding larvae to match prey immediately after the yolk sac is absorbed (“critical period”) and being transported to favorable nursery grounds (“aberrant drift”). This has since been further developed by utilizing new observational data and methods (Cushing, 1990; Houde, 2008; Ottersen et al, 2014). Several environmental factors typically play an important role in the recruitment process, including spatiotemporally varying temperatures, dispersal, light conditions, turbulence, prey availability, and predation (Ottersen et al, 2014)

Methods

Results

Conclusion