Modeling the timing of spawning and hatching of shortnose sturgeon, Acipenser brevirostrum, in the Saint John River, New Brunswick, Canada

• Published in: Canadian journal of fisheries and aquatic sciences 2012-08, Vol.69 (8), p.1316-1328
• Main Authors: USVYATSOV, Sima, PICKA, Jeffrey, SCOTT HARDY, Ryan, DAWSON SHEPHERD, Travis, WATMOUGH, James, KENNETH LITVAK, Matthew
• Format: Article
• Language: English
• Subjects: Acipenser; Acipenser brevirostrum; Animal reproduction; Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; Exploitation and management of natural biological resources (hunting, fishing and exploited populations survey, etc.); Fish migration; Fisheries management; Freshwater; Fundamental and applied biological sciences. Psychology; General aspects. Techniques; Hatching; Larvae; Methods and techniques (sampling, tagging, trapping, modelling...); Rivers; Spawning; Sturgeon; Temperature; Water temperature
• ISSN: 0706-652X; 1205-7533
• DOI: 10.1139/f2012-062

Timing of spawning and hatching of shortnose sturgeon, Acipenser brevirostrum , in the Saint John River, New Brunswick, Canada, was estimated using inverse prediction. We examined egg incubation periods at 5, 9, and 13 °C to back-calculate spawning dates. No larvae hatched at 5 °C. At 9 and 13 °C, hatching began after 18 and 8 days post fertilization, respectively. Lengths of yolk-sac larvae reared in the laboratory at 13–21 °C were used to develop a temperature-mediated Gompertz growth model. The inverted Gompertz model, predicting larval age from larval size and water temperature, was applied to 671, 164, and 746 larvae captured in the wild in 2008, 2009, and 2010, respectively. Estimated hatching distributions peaked in late May, and mean spawning events were predicted to occur in late April – early May (9 °C scenario) and middle to late May (13 °C scenario). Larval ages at the two sampling transects, 4.5 km apart, were similar, while catch per unit effort was lower downstream, indicating mortality during dispersal. Inverse prediction of larval ages provides fast and cost-effective estimates of the timing of spawning, hatching, and larval migration in the wild.