Summer-season populations of epibenthic marine fishes in the Indian River lagoon system, Florida

Epibenthic marine fish populations were sampled in order to establish quantitative baseline data for use in long-term monitoring of the northern Indian River lagoon system, Florida. Fish samples were taken by trawling monthly at 8 fixed stations from June through September 1979 and 1980. Fifty-seven species representing 29 families were collected. The community was numerically dominated by a very few species. Anchoa mitchilli alone accounted for 87% of the 105,853 individuals collected. Abundance, dominance, and species diversity were compared among the 3 lagoon subdivisions – Mosquito Lagoon, Indian River, and Banana River. Greater numbers of fishes were collected in the Indian River, whereas the highest diversity levels were in the Banana River. Although most species were collected in all 3 subareas, inequities occurred in the numbers of individuals taken. For example. Mosquito Lagoon produced significantly more Micropogonias undulatus and Leiostomus xanthurus than either the Indian or Banana rivers. Significantly more Syngnathus scovelli and Anchoa mitchilli were collected in Indian River than in Banana River, and Banana River produced significantly more Lagodon rhomboïdes than did Indian River. The only measured environmental parameters that appeared to be significant in determining fish populations were vegetative cover and salinity. An importance value (IV) index, combining relative abundance, relative frequency of capture, and relative size (biomass) per individual, was calculated for each species in the community. Dominance ranking by IV has advantages over dominance ranking by relative abundance alone and is valuable for making comparisons in a long-term monitoring study.