Preliminary Captive Burbot Spawning Observations
Nathan R. Jensen, Scott R. Williams, Susan C. Ireland, John T. Siple, Matthew D. Neufeld, and Kenneth D. Cain
Abstract.—Localized population declines of North American burbot Lota lota maculosa have prompted interest in developing artificial propagation techniques for recovery efforts. Twenty adult burbot were observed over two consecutive spawning seasons to evaluate the feasibility of captive spawning and the ability to successfully incubate eggs. Preliminary spawning attempts (year 1) were successful and incorporated two forms of exogenous hormone (GnRH) analog to synchronize (foreshorten) female spawn timing. Mean days to spawn (post hormone delivery) were significantly (P < 0.05) reduced in female burbot given an implantable GnRH analog compared to females allowed to ovulate naturally. A high percentage (69%) of fish released gametes in holding tanks (volitional spawning) in year 1. In year 2, hormone treatments were administered to all females, and sexes were segregated in an attempt to control volitional spawning. Despite segregation, volitional spawning occurred, which suggests that chemical signals may play a larger role than physical contact for initiation of spawning. Viable gametes were obtained and incubated each year and ranged in diameter from 0.7 to 1.1 mm. Methods to enumerate eggs and estimate fertilization rates were developed and fertilization rates ranged from 10% to 80%. Nearly all fish (92%) spawned over consecutive years, but gamete quality appeared to be reduced during year 2.