On the Feeding of the Hagfish Myxine Glutinosa in the North Sea

Extract

The myxinoid cyclostomes, of which the hagfish Myxine glutinosa L. is one of the best known examples, are of unique biological interest as representatives of a group of jawless vertebrates which probably had their origin in the pteraspidomorph ostracoderms of the Ordovician era (Nybelin, 1973). They have been much studied by comparative anatomists and physiologists but somewhat neglected by ecologists. There is, for instance, very little critical information on their normal feeding biology. Perhaps one reason for this is that, although hagfish may be extremely abundant locally (their principal habitat requirements are stable, soft muddy sediments and a salinity in excess of 31 %, (Gustafson, 1935)), they tend to be missed by most exploratory fishing and biological sampling programmes. This is because benthic sampling techniques are often ill-adapted for the capture of large active organisms capable of swimming and burrowing and because, unless blocked by the catch, the cod-end mesh sizes of the trawls used by most British commercial fishermen would easily permit the escape of even the largest hagfish. However, the research otter trawls used by the Department of Agriculture and Fisheries for Scotland (D.A.F.S.) for surveying the North Sea stocks of the deep water pink shrimp, Pandalus borealis Krøyer, are fitted with cod-end covers of small mesh, and it is found that the catches frequently include small numbers of hagfish, presumably caught while swimming close to the bottom, or possibly when buried in the surface of the sediments. The present study is largely based on the examination of hagfish collected during the D.A.F.S. Pandalus surveys of 1975 and 1976. The remaining material was kindly provided by Dr J. B. Buchanan of the Dove Marine Laboratory at Cullercoats, Northumberland.