Abstract
Adult wolf eel (Anarrhichthys ocellatus) breeding pairs (out-crossed brood years 1995 and 2001) located at two different sites (the Vancouver Aquarium and the DFO/UBC-Centre for Aquaculture and Environmental Research) each had previous histories of producing unfertilized eggs. In each of these years and at both sites, the females appeared to be ovulating and releasing normal eggs; therefore, the cause of these unsuccessful fertilizations were attributed to the males not being fully mature. This past spawning season (2009-2010), the male wolf eel located at the DFO/UBC-Centre for Aquaculture and Environmental Research was implanted with OvaplantTM (Syndel Laboratories Ltd., Qualicum Beach, BC). This implant contains 75 µg of a synthetic analogue of salmon GnRH, which was injected into the base of the dorsal fin (ridge) in the anaesthetised male. The implanting of this male was performed at a time when spawning had occurred in previous years, and when the female showed similar signs and behaviour that spawning was imminent (i.e., a distended abdomen). Approximately one week post-implantation, the female spawned and the male successfully fertilized the eggs, which resulted in a large, cohesive egg mass. The egg mass was removed from the tank and incubated in an inverted basket with a constant high flow of 8°C seawater. Egg development was monitored throughout the incubation period by removing samples from the egg mass on a weekly basis. Sampling continued up to the start of hatching (approximately 3 months post-fertilization).
The effect of OvaplantTM in facilitating male maturation and successful breeding of wolf eels was later examined again by similarly implanting the male wolf eel located at the Vancouver Aquarium. Approximately 10 days post-implantation, a large cohesive mass of fertilized eggs was observed within the wolf eel den. The use of hormone implants and the development of various incubation and husbandry techniques have demonstrated that wolf eels can be successfully bred and reared in captivity. The implications of these results are of interest not only for aquariums worldwide, but also for those interested in using wolf eels for aquaculture in the live market food industry.
Acknowledgements
The authors would like to thank the assistance of Dr. M. Haulena, W. Wong, D. Carlson, K. Kaufman and C. Heaven in this project. We would also like to acknowledge the support from Fisheries and Oceans Canada (ACRDP) and Island Scallops Ltd.