Recruitment variability in North Atlantic cod and match-mismatch dynamics

Area of Science:

• Marine Ecology
• Fisheries Science
• Climate Change Impacts

Background:

• Fisheries exploitation, habitat destruction, and climate variability impact recruitment success in marine ecosystems.
• Understanding recruitment variability is crucial for addressing declines in key fish species.
• The match-mismatch theory links successful fish recruitment to the timing of larval fish abundance and prey availability, but mechanisms remain unclear.

Purpose of the Study:

• To investigate the influence of ocean temperature on larval cod (Gadus morhua) survival.
• To quantify spatial differences in recruitment success drivers.
• To test the match-mismatch theory in North Atlantic cod populations.

Main Methods:

• Utilized empirical data on larval fish abundance.
• Employed a mechanistic individual-based model to simulate larval survival.
• Analyzed ocean temperature reanalysis data from 1960 to 2002.

Main Results:

• Modeled survival rates of larval cod (Gadus morhua) across four North Atlantic spawning sites.
• Found substantial increases in cumulative survival during warmer years (308% to 385% for specific stocks).
• Observed that match-mismatch dynamics become more critical at higher latitudes.

Conclusions:

• The duration of overlap between larval fish and prey is more critical for survival than peak timing.
• Warmer years prolong this overlap due to earlier spring blooms, enhancing growth and survival.
• Prolonged overlap leads to more large individuals with better recruitment potential.