Abundance, distribution and species composition of fish larvae in the Swartkops estuary

Abstract

A two-year quantitative survey of the ichthyoplankton of the Swartkops estuary has resulted in the identification of 17 larval fish. The ichthyoplankton was present through all months of the year, but was only abundant during the summer months (November-February). During both years sampled, thehighest densities were recorded in December. An attemptwas made to correlate the data with environmental parameters such as temperature, salinity and rainfall. The ichthyoplankton of the Swartkops is dominated by few species. The family Gobiidae (59,44%) and a clupeid species, Gilchristella aestuarius (31,12%), accounted for 90,56% of all the fish larvae sampled. The family Gobiidae were most common in the mouth and lower reaches of the estuary, while G. aestuarius dominated the mid- and upper estuary.