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Life history of Spurdog

From Life History of the Piked Dogfish (Squalus acanthias L.) in Swedish Waters
Charlott Stenberg Fiskeriverkets Utredningskontor, Göteborg, Sweden

The piked, or spiny, dogfish, Squalus acanthias, is a common shark in the Atlantic, the Pacific Ocean and in the Black Sea.

Jones and Geen (1976) studied whether the piked dogfish in the Pacific Ocean should be classified as a species of its own, Squalus suckleyi, as it has been in other studies, or if it is in fact the same species in both the Atlantic and the Pacific Ocean.

After electrophoretic analyses of muscle tissue and blood, comparing morphometric ratios and the number of vertebra on sharks from North America’s east and west coasts, their conclusion was that the differences between the populations were not big enough to classify the population of the Pacific Ocean as a subspecies of the piked dogfish from the Atlantic Ocean.

On the other hand many researchers write about the possibility of physiological differences or differences in the metabolic rate that can exist between the sharks in the different oceans.

Ketchen (1975) wrote that it seems as if the piked dogfish in the Atlantic Ocean have a more rapid initial growth, become sexually mature earlier and do not attain the same size as its relatives in the Pacific Ocean. Most probably they do not reach the same age either.

Something that does not seem to differ between the piked dogfish in the Atlantic and the Pacific Ocean is that it takes between 20 and 23 months for the embryos to develop after fertilization (Holden and Meadows, 1964; Jones and Geen, 1977b). On the other hand Kirnosova (1989) maintains that the piked dogfish in the Black Sea only needs 12 months for the same process.

The study examines the life history of the piked dogfish in Swedish waters

Posted in: Infocentre
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