Transatlantic Journey of a Tagged Cod

Abstract

ALTHOUGH cod (Gadus morhua) populations in the North Atlantic form more or less discrete stocks, many tagged cod have travelled long distances, for example, between Iceland and Greenland, from Iceland to the Faeroes, and the Faeroes to the North Sea¹, and from Bear Island to Iceland and Greenland². Since 1956 more than 4,000 cod have been tagged in the central North Sea from English vessels, and until this year none had been returned from outside the North Sea. On January 4, 1962, the Lea-type tag³ No. 1137 which had been attached by a monofilament nylon loop between the first and second dorsal fins to a cod caught on the North-west Rough (central North Sea, 55° 6′ N., 1° 24′ E.) on June 9, 1957, was handed to Mr. G. R. Williamson by a member of the crew of the Polish stern trawl factory ship Kastor at St. Johns, Newfoundland, as having been caught on the Grand Banks. At the time no special significance was attached to this fish, as it was presumed to have been tagged in the Newfoundland area. When the exceptional movement was known, further inquiries were made through Mgr. Jozef Wolek, director of the Polish Sea Fisheries Institute, Gdynia, who visited the ship and interviewed the fishermen. They confirmed that the fish was caught on December 7, 1961, on the north-eastern slope of the Grand Banks (47° 54′ N., 47° 54′ W.) in 300–320 m., as witnessed by several fishermen, including the second mate. The fish was still alive, with the tag attached normally, and was measured before the tag was removed and the fish sent for filleting and freezing. It had grown from 57 cm. total length when tagged to 75 cm. when recaptured. In the North Sea a 60-cm. cod might grow 15 cm. a year, but on the north-east slopes of the Grand Banks only about 3 cm. a year.