Tide-dependent Predation Patterns of Piscivorous Fishes in Shallow Estuarine Creeks

• Main Author: Helms, Matthew Ross
• Format: Thesis
• Language: unknown
• Published: CCU Digital Commons 2015
• Subjects: Estuaries; Fish; Predators; Salt Marsh; Tidal Creeks; Tides; Ecology and Evolutionary Biology; Minnows; Near Creek; Red drum
• Online Access: https://digitalcommons.coastal.edu/etd/21; https://digitalcommons.coastal.edu/cgi/viewcontent.cgi?article=1020&context=etd

The distribution and foraging behavior of predatory salt marsh fishes is shaped by the movements of prey, many of whom seek shelter in shallow and tributary creeks. I hypothesized that the distribution of piscivorous fishes in marsh creek channels would differ with proximity to the mouths of intertidal creeks and with tidal stage. Custom-built trotlines baited with live minnows were deployed during four discrete tidal stages at two microhabitats in main creek channels: (1) adjacent to intertidal creek mouths, and (2) along straight banks in North Inlet estuary, South Carolina. Catch-per-unit-effort of predatory fishes was significantly higher (Wilcoxon signed-rank tests, p < 0.05) near creek mouths during all tidal blocks except the period between slack high tide and mid-ebb. I infer that these predators were attempting to intercept prey species that enter and leave small creeks that offer refuge during high tides. A total of 176 animals representing 14 species were captured, with Atlantic sharpnose sharks, Atlantic stingrays, ladyfish, and red drum composing 88.7% of the catch. The ability to predict spatial and temporal distributions for these and other piscivores improves our understanding of trophic and ecosystem function and may aid in the management of recreational fisheries.