Response of individual shoaling Atlantic cod to ocean currents on the northeast Newfoundland Shelf

Abstract

The movements of sonically-tagged Atlantic cod swimming within a large (80,000 mt) shoal of post-spawning ®sh on the northeast Newfoundland Shelf were related to the acoustically determined position of the shoal and event structure in the local ocean currents. For the ®rst several days of the study, a period when currents were unfavorable for shoreward transport, the tagged ®sh maintained station. There was little net movement of individual ®sh and no change in the geographical location of the shoal. Then, apparently in response to a shoreward current event, the cod moved with the¯ow. The tagged cod behaved as members of the shoal, in that their net movement was similar to that of the shoal itself. These observations further support the hypothesis that cod on the northeast Newfoundland Shelf selectively use currents for transport during their shoreward feeding migration. The cue to initiate migration by post-spawning cod is apparently an organized onshore¯ow exceeding a threshold velocity and duration. #

Migration route familiarity and homing of transplanted Atlantic cod (Gadus morhua)

“…However, any movement with prevailing currents is more likely to be a result of active rather than passive transport. Observations of the selective use of currents by migrating cod (Arnold et al, 1994;Rose et al, 1995;Wroblewski et al, 2000), as well as observed migrations of postspawning cod moving against the prevailing currents in Placentia Bay (Lawson and Rose, 2000) support this claim. It is unclear how prevailing currents may provide directional clues to homing cod.…”

Acoustic approaches to remote species identification: a review

“…A miniature electronic pinger is placed subcutaneously or in the abdominal cavity of an individual animal. Hydrophones are then used to track the animal’s horizontal and vertical movements (Arnold and Greer Walker, 1992; Wroblewski et al ., 1994, 2000). Tags transmit at specific frequencies to provide a unique marker for each individual.…”

Analysis on Chaotic Behaviour of Movements of Sea Bream and Halibut in Open Sea

“…Tracking of fish in the sea was investigated to locating movement of fish such as flat fish 1,2,3,4), cod 5,6,7,8), saithe 9) and mackerel 10,11) etc.…”