Ecological Aspects of the Distributions of Fishes at Fanning Island

Abstract

The nearshore marine environment of Fanning Island (30 55' N, 159 23' W) was subjectively partitioned into seven habitats which are briefly described. Efforts were made to sample in each in order to obtain as complete as possible a record of the fish species present. Observations were made underwater by skin and SCUBA diving during July-August 1972, and April 1973; 214 species of fishes (96 genera in 37 families) were seen. Tables provide semiquantitative abundance estimates for each species in every habitat, and a list of characteristic species associated with various substrates within the habitats. Semiquantitative abundance estimates were used to generate diversity estimates and two measures of faunal resemblance for the habitats taken two at a time. Relationships between the faunas of the different habitats were used to generate hypotheses about ecological relationships between habitats. It is argued that strong surge and tidal currents strongly influence the distributions of Fanning Island fishes, separating outer reef fishes from lagoon fishes by a rich zone associated with the English Harbor channel. Our observations include the addition of 57 species to the Line Islands fish fauna. Their zoogeographical affinities support an earlier determination of a central Pacific character for the Line Islands fishes.