Fine-scale activity, distribution and habitat utilization of Atlantic cod (Gadus morhua) on the Ipswich Bay spawning ground

• Main Author: Siceloff, Laughlin
• Format: Text
• Language: unknown
• Published: University of New Hampshire Scholars' Repository 2009
• Subjects: Biology; Oceanography; Agriculture; Fisheries and Aquaculture; atlantic cod; Gadus morhua
• Online Access: https://scholars.unh.edu/thesis/460; https://scholars.unh.edu/context/thesis/article/1459/viewcontent/1466953.pdf

Data storage tags (DSTs) and acoustic telemetry were applied to examine cod spawning habitat utilization in Ipswich Bay and compare seasonal activity patterns. I tagged 200 spawning cod in Ipswich Bay during April--May 2006 with DSTs recording depth and temperature. Twenty-six cod were also implanted with acoustic transmitters and relocated manually and with stationary listening stations during May and June. Twenty-five DSTs were returned, showing that most cod departed the spawning ground during May and June and dispersed throughout the western Gulf of Maine. Cod shared a low vertical activity pattern in Ipswich Bay, but adopted various site-specific vertical behaviors alter leaving. Spawning activity was concentrated in a ∼35 km2 area where cod aggregated alongside particular bathymetric features. These fine-scale movement and spawning data have implications for area closures, defining Essential Fish Habitat, and identifying cod population structure in the Gulf of Maine.