Banded Sculpin (Cottus carolinae) Life History Trait Variation Across a Stream Size Gradient

Environmental gradients shape the distribution and abundance of stream fishes by filtering life history traits. According to life history theory, trade-offs related to survival, growth, and reproduction affect the ability of fishes to inhabit streams with contrasting hydrologic regimes. We measured life history trait variation for Banded Sculpin (Cottus carolinae) across stream sizes (orders 2-5) to test for life history trait variation across a hydrologic gradient. We measured population size and age structure to assess survival, condition factor and otolith annuli to assess growth, and gonadosomatic index (GSI) and oocyte counts to assess reproduction. Survival was greater at two hydrologically stable sites compared to two sites with more variable hydrology, and distinct age groups dominated by younger age classes were apparent at hydrologically variable sites. Condition factors were similar among sites, but growth rates were greater at hydrologically variable sites with higher summer water temperatures. Reproductive investment measured as GSI was also greater at hydrologically variable sites with lower winter water temperatures that corresponded with spawning. Our study reveals Banded Sculpin expresses intermediate life history traits with some plasticity, and we suggest this is at least one mechanistic underpinning for the occurrence of the species across streams of varying size.