The Interaction between offshore cod trawlers and harp (Phoca groenlandica) and hooded (Cystophora c
David Pemberton,* Bora Merdsoy, Rosemary Gales* & Deane Renouf
*Department of Parks, Wildlife and Heritage, P.O. Box 44A, Hobart, Tasmania, Australia
Ocean Sciences Centre, Memorial University of Newfoundland, St John's. Newfoundland. Canada A I C 5S7
Biological Conservation. 1994. Elsevier Science Limited.
Abstract: The direct interaction between the seals and the trawl or dragger fishery results in seals being trapped in trawler nets and either drowned, released, or killed. A study undertaken between 17 and 27 February 1992 showed that more seals interacted with the net whilst fishing for Atlantic cod (Gadus morhua) in 450 fathoms of water (10 - 60 seals) than when fishing for witch (Glyptocephalus cynoglossus) in over 750 fathoms of water (0-6 seals). Seals were captured only whilst fishing for Atlantic cod (eight harp seals and two hooded seals). Harp seals (Phoca groenlandica), (33.2 +/- 21.8), were more plentiful around the trawler than hooded seals (0 80 +/- 0.4) and adult male harp seals were most common (73%). The impact of seals on the caught fish was negligible with less than 0.002% of the catch being taken by seals. All observations (n=32) of seals eating Atlantic cod showed that they swallowed them head first and whole. The number of seals captured can be reduced by altering setting methods, and the provision of a runway for the seals over the work deck to the side of the trawler would obviate the need to kill them. We hypothesize that the apparent increase in harp seal/trawler interactions is the result of smaller catches of cod, with consequential decrease in spillage from the nets requiring the seals to enter the nets to obtain cod. This results in increased by-catch of seals.