Seasonal Distribution and Abundance of Tidepool Fishes at Six Locations within the Southern California Bight, 2004-2005

Abstract

Abstract. Several studies have been conducted on the California coast investigating the distribution and abundance patterns of rocky intertidal fishes; however, most of these studies have focused on only one or two sites along a large expanse of coastline primarily north of Point Conception. This study examined six sites in the central portion of the Southern California Bight to assess regional patterns of abundance and distribution of rocky intertidal fishes more accurately. All six sites were sampled within the same low tide series quarterly from January 2004 to February 2005. Species abundances, biomass, densities, species diversity (H′), and size distributions were determined and compared. All assemblages were dominated by Clinocottus analis (Cottidae) both in abundance and biomass although a total of ten species were found throughout the study representing six families. Species composition did vary with latitude as warm temperate species, Girella nigricans and Gobiesox rhessodon, were associated with southern sites, and cool temperate species, Clinocottus recalvus and Oligocottus snyderi, were found at northern sites. Differences in community structure may reflect site specific environmental conditions such as surfgrass coverage or wave energy. When considering abundance and density, each metric yielded a different result, i.e., the site with greatest abundance had the lowest density. This may be reflective of a funneling effect of intertidal fishes from surface area of habitat available at high tide to low tide rather than simply standardizing for pool size. H′ was not influenced by season or latitude but was negatively correlated with wave exposure. Three of the five most common species (Clinocottus analis, Girella nigricans and Gobiesox rhessodon) recruited in the late fall, early winter. Assessment of Clinocottus analis by site revealed regional variation: recruitment was only detected at the three southern sites in January 2004 but at all six sites in February 2005.