Long-term variability in spawning stock age structure influences climate-recruitment link for Barents Sea cod

Area of Science:

• Marine Ecology
• Fisheries Science
• Population Dynamics

Background:

• Fish recruitment, a critical factor in population dynamics, is influenced by spawning stock characteristics and environmental conditions.
• Understanding the interplay between spawning stock state and environmental factors is essential for predicting recruitment success.
• Previous research suggests a link between spawning stock age structure and vulnerability to environmental fluctuations.

Purpose of the Study:

• To investigate if the relationship between environmental conditions and fish recruitment is modulated by the spawning stock's state.
• To re-evaluate the hypothesis that recruitment is more vulnerable to environmental changes when the spawning stock is composed of younger fish with limited age diversity.
• To extend the temporal data series for the Barents Sea Atlantic cod stock to strengthen the analysis.

Main Methods:

• Analysis of a long-term dataset (1922-2019) for the Barents Sea Atlantic cod stock.
• Examination of correlations between spawning stock attributes (biomass, mean age, age diversity) and recruitment.
• Assessment of how environmental fluctuations interact with spawning stock characteristics to affect recruitment.

Main Results:

• Findings support the hypothesis that recruitment is more susceptible to environmental variability when the spawning stock is dominated by young fish and has low age diversity.
• The extended time series strengthens the evidence for the proposed relationship.
• Correlative analyses indicate a significant interaction between environmental status and spawning stock structure in influencing recruitment.

Conclusions:

• The state of the spawning stock, particularly its age structure, plays a crucial role in mediating the impact of environmental conditions on fish recruitment.
• Fisheries management strategies should incorporate environmental status alongside spawning stock considerations for effective stock management.
• These findings reinforce the importance of maintaining diverse and mature spawning populations for resilient fisheries.