COUNTERGRADIENT VARIATION IN GROWTH OF YOUNG STRIPED BASS (MORONE-SAXATILIS) FROM DIFFERENT LATITUDES

Common garden experiments were undertaken to test the hypothesis that the genetic capacity for growth of striped bass (Morone saxatilis) var ies inversely with length of the growing season across a latitudinal g radient (i.e., countergradient variation (CnGV) in growth). Newly hatc hed larvae were obtained from six native anadromous stocks spanning mo st of the natural range of striped bass (Florida to Nova Scotia). Grow th experiments were conducted under conditions of unlimited food at th ree temperatures (17, 21, 28 degrees C) and commenced after larvae had exhausted maternal energy resources (i.e., yolk and oil) and had begu n to metamorphose. Mixed-model nested ANOVA demonstrated that length a nd dry weight growth differed significantly among latitudes in most co mparisons. South Carolina fish ranked consistently as the slowest grow ing group in virtually all comparisons, but the rank order of the othe r latitudes differed among trials. North Carolina and Gulf of Mexico f ish generally had intermediate rates of growth whereas New York, Maryl and, and Nova Scotia fish generally had the highest growth. Overall, t he average growth rate of progeny from the 28 mothers tested in this s tudy had a strong positive correlation with latitude of origin, strong ly indicating CnGV in growth.