Overwinter survival of juvenile Atlantic cod (Gadus morhua) in a costal ecosystem ...

• Main Author: Geissinger, Emilie A.
• Format: Text
• Language: English
• Published: Memorial University of Newfoundland 2022
• Subjects: atlantic cod; Gadus morhua; Newfoundland
• Online Access: https://dx.doi.org/10.48336/kqwv-fj98; https://research.library.mun.ca/15804/

Acknowledging poor understanding of natural mortality in juvenile fish, especially throughout first winter, I synthesized past studies that suggest that physiological and metabolic stress in the first winter result in a critical survival period that determines cohort strength. Juvenile Atlantic cod (Gadus morhua) in coastal Newfoundland settle in nearshore habitats in 3-6 pulsed events each year, creating a broad size-structured age-0 year-class with potentially different survival trajectories entering their first winter. To assess size-specific survival across winter, I classified age-0 and age-1 pulse structure using finite mixture distribution models. I evaluated juvenile cod survey data and archived juvenile cod samples with winter temperature records to determine effects of winter duration, body condition, and settlement time on overwinter survival. Higher condition entering winter and smaller size combined with earlier fall settlement all improved overwinter survival among pulses. Increased body ...