Toxin in the Flesh of the Greenland Shark and Other Arctic Animals

Extract

The poisonous properties of shark meat have long been a subject of interest to travellers and dwellers in northern regions. In a short but important paper (Medd. om Grønland. Bd. 125, Nr. 5, 1939, pp. 1–16) Ove Bøje gives the results of an investigation at Upernavik. He summarises former knowledge of the subject derived from both European and native sources, and goes on to an account of his experiments on sledge-dogs. Similar in their effect to the flesh of the Greenland shark (Somniosus microcephalus), though to a lesser extent, are the meat of the “uvac” or Greenland cod (Gadus ogac) and the sea scorpion (Cottus scorpius), and sometimes, with weakly subjects, the flesh of the halibut (Reinhardtius hippoglossides). Similar, but apparently not the same, are the poisonous qualities of the liver of the polar bear, the bearded seal and the Greenland sledge-dog. The toxin in the shark meat apparently is inactivated, but not destroyed by the drying process to which the flesh is normally subjected before being given by the Eskimo to his dogs. Enzymes present in the fresh tissues of any animal can apparently re-activate the toxin in the shark flesh if the two types of meat be eaten together. A number of hypotheses are discussed, and there seems to be some evidence for believing that the toxin may be derived from the common food of these various fishes on the Greenland coast in the autumn. This consists of a pelagic mollusc (a Pterapod, Limacina helicina), and the “uvac” and even eider ducks sometimes themselves show symptoms of poisoning after feeding on this food. The author regrets that so far he has been unable to undertake detailed chemical analysis of the flesh of the species in question. Judging by symptoms he considers that the toxin is probably related chemically to muscarine (a fungal poison).