Hard life in cold waters: Size distribution and gonads show that Greenland halibut temporarily inhabit the Siberian Arctic

Abstract

The range of the Greenland halibut Reinhardtius hippoglossoides (Walbaum, 1792) includes vast areas in the northern parts of the Atlantic and Pacific oceans, as well as the seas of the Arctic Ocean. Despite its commercial importance and decades of study, many aspects of its life cycle and reproduction remain poorly understood. Here, we evaluate the size distribution of Greenland halibut in the catches of research surveys in the Barents, Kara, and Laptev seas and conduct micro- and macroscopic studies of their gonads in the Laptev Sea. The size of Greenland halibut individuals increases from west to east, which is associated with the settling of pelagic juveniles and the subsequent residency of growing individuals near their settling sites. To the greatest extent, this size imbalance is manifested in the areas most remote from spawning grounds, i.e. the Kara and Laptev seas. The process of maturation in large individuals of Greenland halibut in the Arctic seas is characterized by a state of inhibition-waiting in the early stages of gametogenesis (previtellogenesis). The data obtained indicate that Greenland halibut in the North Atlantic and the Siberian Arctic have a continuous range. The continental slope of the Barents Sea is a spawning and maturing ground, while the northern parts of the Barents and Kara seas, as well as the continental slope of the Laptev Sea, are feeding grounds for juveniles. The results of this study might serve as a necessary basis for monitoring condition of halibut stocks as well as for reallocation of the total allowable catch between countries that exploited them in the Norwegian and Barents seas.

Keywords

• Reinhardtius hippoglossoides
• Lifecycle
• Reproduction
• Testes
• Ovaries
• Spawning ground