Characterizing spawning behavior of Greenland halibut (Reinhardtius hippoglossoides) in the eastern Bering Sea and Aleutian Islands

2 Department of Fisheries College of Fisheries and Ocean Sciences University of Alaska Fairbanks P.O. Box 757220 Fairbanks, Alaska 99775 Abstract—Understanding spawning behavior of commercial fish populations provides a basis for making management decisions related to these stocks. Archival tags can be used to define spawning behavior when depthspecific movements are involved. Spawning behavior of Greenland halibut (Reinhardtius hippoglossoides) in the eastern Bering Sea and the Aleutian Islands was inferred from archival tag data. The predominant period of identified spawning activity, based on abrupt vertical rises of females, occurred in January and February, and females reached apexes in their upward movement (spawning rises) at depths of approximately 200–350 m below the surface, indicating that the release of eggs could occur at depths shallower than previously assumed. Females had a single spawning rise annually, a result supporting the notion that this species is a total (singlebatch) spawner. Male Greenland halibut exhibited spawning behavior, rises to shallower depths one or more times, for an average of 20 d. For large female Greenland halibut (>80 cm in fork length), spawning rises occurred in consecutive years, indicating that, despite oocyte development taking more than 1 year, spawning occurs annually. Inferring spawning behavior by using data collected with archival tags can aid in understanding the maturity of Greenland halibut.