Early development of Northeast Arctic Greenland halibut (Reinhardtius hippoglossoides)

Abstract

The early development of the Greenland halibut (Reinhardtius hippoglossoides) has not been described. This study presents some preliminary notes on the egg development of the Northeast Arctic Greenland halibut. Buoyancy and morphometric characteristics of artificially spawned eggs are compared with field sampled eggs, in order to identify these to species. The eggs in the ovary of ripening females were large (about 4 mm), transparent, almost equal in size and stuck to the walls of the ovary. In running, artificially spawned females the ovulated eggs were all easily released in one batch. This may indicate that Greenland halibut has a comparatively long period between each egg batch delivered. Artificially spawned eggs of the Greenland halibut had a diameter varying from 3.3 to 4.2 mm and a neutral buoyancy in seawater of ca. 33‰ (c. 5°C) during the first four days of development. During gastrulation the egg density increased until closure of blastopore. Eggs from field surveys had a diameter raging from 3.9 to 4.7 mm and a neutral buoyancy in seawater of 35.2‰ (ca. 5°C). This corresponds to a density near 1.0279 g/cm3. This density is found at depths around 650 m (34.9‰ salinity and 1.8°C) in the spawning area. The eggs hatched after nearly two months of incubation at ca. 2°C. The embryo seemed to hatch at a premature stage.