Captive Spawning and Egg Quality of CALIFORNIA YELLOWTAIL Seriola dorsalis

The lack of knowledge in what optimizes egg and larval quality is an important limiting factor in developing culture techniques for any species. Inconsistent or poor egg quality significantly affects the production of larval and juvenile fish. Egg quality is a known predictor of subsequent larval viability, quality, and stress resistance. Without high quality eggs, it is not possible to optimize husbandry practices.

Here we tracked egg quality in a population of California yellowtail (Seriola dorsalis) housed at the Hubbs-Sea World Research Institute.  We used spawn events from three consecutive years and monitored basic egg quality metrics such as: spawning frequency, spawn viability, egg diameter, oil diameter, hatch rates, larval size at hatch, and larval survival to first feeding.  Along with these metrics we also ran parentage analysis on all the spawning events.  Finally, we ran proximate composition and fatty acid analysis of select spawning events to assess nutrient resources of good, fair, and poor spawn events.

Between 2014 and 2015 there was an increase in the spawning events but a decrease in the total eggs produced.  Using parentage analysis we found that a single female was responsible for a majority of the spawn events (39%), and those spawn events were mostly of poor quality.  Based on this result the female was removed prior to the 2016 spawning season.  In 2016 spawn quality improved while number of spawn events and eggs produced decreased.    

Proximate composition analysis (PC) and fatty acid analysis (FA) showed differences between good (>70% viability), fair (31-69% viability) and poor (0-30% viability) batches of eggs.  Poor spawns had significantly more protein than eggs from good spawns.  Significant differences in FA composition attributable to quality were also detected in egg samples.  The proportion of arachidonic acid (ARA) in eggs from fair spawns was 20% higher than eggs from good spawns and 14% higher than eggs from poor spawns. Compared to good and poor spawns, fair spawns also had a lower ratio of eicosapentaenoic acid (EPA) to ARA ratio. Last, fair spawns had a higher proportion of 22:5 n-3 than good spawns, but were not different from poor spawns