Minor Olafsen Research Articles

Gyrodactylus anarhichatis n. sp. and G. microanchoratus n. sp. (Monogenea: Gyrodactylidae) from the Atlantic wolf-fish Anarhichas lupus (Anarhichadidae) off the coast of Norway

The gyrodactylid monogeneans Gyrodactylus anarhichatis n. sp. and G. microanchoratus n. sp. are reported from the skin and fins of wild Atlantic wolf-fish Anarhichas lupus L. caught off the coast of northern Norway. G. anarhichatis n. sp. is also reported from farmed Atlantic wolf-fish and spotted wolf-fish A. minor Olafsen. G. anarhichatis n. sp. most closely resembles G. corti Mizelle & Kritsky, 1967, but is also similar to G. perlucidus Bychowsky & Poljansky, 1953 and G. errabundus Malmberg, 1970, while G. microanchoratus n. sp. differs from most other Gyrodactylus spp. by having marginal hooks longer than anchors and a peculiar lump on the marginal hook sickle toe pointing towards the sickle point.

Growth rates of the common wolffish, Anarhichas lupus L., and spotted wolffish, A. minor Olafsen, in captivity

. Field-caught fry of the common wolfish, Anarhichas lupus L., and the spotted wolffish, A. minor Olafsen, were reared on a commercial dry pellet. Both species experienced the same environmental conditions, including an annual fluctuation in temperature from 5·8 to 13·7°C. The spotted wolffish reached 1·58 kg in 2 years from hatching, more than four times the weight of common wolffish (0·37kg). Analysis showed that for both species the specific growth rate decreased with increasing fish size and increasing temperature. Estimates, based upon optimum conditions, indicate that the spotted wolffish would reach a total wet weight of 5 kg (<7°C) in 2 years from hatching, and the common wolffish (7–9°C) a total wet weight of 2·5kg within that same period. Female common wolffish matured at a weight above 0·5kg, whereas those of the spotted wolffish matured at a weight above 2·5kg. The spotted wolffish had a significantly higher fillet proportion (∼50%) than the common wolffish (∼45%) and a significantly lower hepato-somatic index (3·7% and 5% respectively).