Growth of juvenile Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) in response to dual-season spawning and latitudinal thermal regimes

Erin L. Markin, David H. Secor
2020 Fishery Bulletin  
sturgeon (Acipenser oxyrinchus oxyrinchus) occur over a broad latitudinal range, such that size-dependent winter mortality of juveniles could select for latitudinal countergradient variation in growth rate of juveniles. To investigate latitudinal countergradient variation in growth between populations, growth of strains of the Saint John River (New Brunswick, Canada) and the Altamaha River (Georgia) was compared in a common-garden experiment by exposing juveniles (Altamaha River strain: mean
more » ... gth of 178 mm [standard deviation (SD) 8.1]; Saint John River strain: mean length of 180 mm [SD 9.2]) to simulated temperature regimes representing the latitudinal range of this subspecies (in the Saint John, Choptank, and Edisto Rivers). No strain effect was detected. To evaluate thermal phenology, a growth-degree-day (GDD) model was developed from responses of fish in a laboratory. Growth degree days were predicted for juveniles that spawned in the fall and for systems south of Chesapeake Bay, where supraoptimal summertime temperatures occur. Predicted lengths of age-1 Atlantic sturgeon generally fell within the range of values reported in literature. Results of analyses with the GDD model support evidence that spawning occurs in the fall only in systems south of the New York Bight, and the model could be applied in evaluation of scenarios of warming and dual-season spawning throughout the range of this subspecies. Abstract-Populations of Atlantic
doi:10.7755/fb.118.1.7 fatcat:obe45zakgzcmtjqe2qzxbfsm34