Meeting Abstract

94.4  Wednesday, Jan. 7  Effect of Rearing Temperature on the Onset and Duration of Dispersal of Early Life Stages of Shortnose Sturgeon PARKER, E.L.*; KYNARD, B.; PARKER, T.K.; KYNARD, B.E.; USGS, Conte Anadromous Fish Research Center; BK-Riverfish, LLC.; BK-Riverfish, LLC.; BK-Riverfish, LLC. eparker@usgs.gov

Shortnose sturgeon (Acipenser brevirostrum) undergo a downstream dispersal during the larval life stage. The objective of this study was to determine the effect of three temperature regimes on the timing and pattern of downstream dispersal of Connecticut River (MA, USA) shortnose sturgeon larvae. Tests were conducted in artificial stream tanks with three replicates at each of three temperatures, 10, 15, and 20C. Fish were introduced to experimental tanks immediately upon hatching, and their movements were monitored day and night with video cameras. Rearing fish at 10C caused development to slow and delayed the onset of dispersal. Fish in the 10C group had a single peak of dispersal lasting 8 days. Increasing the temperature (15 and 20C) caused fish to begin dispersing at a younger age (in days after hatch), but also produced a dispersal with multiple peaks. Fish were all at or close to the beginning of the larval life stage (i.e. beginning exogenous feeding) and were all morphologically similar when they began dispersing, regardless of temperature. Fish in the 15 and 20C treatments required a similar number of degree-days to become larvae, but fish in the 15C group took more degree-days to begin dispersal than fish in the 20C group. Fish in the 10C group took many more degree-days both to become larvae and to initiate dispersal than fish in the other two groups. These results show development and dispersal of shortnose sturgeon early life stages can be influenced by river temperature, and anthropogenic impacts that alter river temperature regimes have the potential to affect sturgeon dispersal patterns.