Fish larvae were sampled in the entrance channel and in the two basins of the permanently open
Nornalup-Walpole Estuary, on the southern coast of Western Australia, in each month between October
1989 and September 1990. Sampling yielded a total of 39 068 larvae belonging to 36 species and 23
families, with the engraulidid Engraulis australis (56.7%) and the gobies Pseudogobius olorum (24.4%)
and Favonigobius lateralis (15.0%) being the most abundant species. Most of the larvae were caught
between November and March, with the concentrations of the most abundant species reaching peaks
between January and March, when water temperatures had reached 21-24�C. In terms of number of larvae,
the larval fish assemblage in the basins was dominated by species that spawn within the estuary, with the
larvae of these species contributing ≥98.7% to the totals at the basin sites. Although the larvae of 26 marine
species were caught in the entrance channel, these were either rare or absent in the basins, except for those
of the terapontid Pelates sexlineatus, which were moderately abundant in the outer basin. The fact that the
larvae of most of these marine species were at the preflexion stage, and that all but three of those species
had never been previously recorded as either juveniles or adults within the system, indicates that they were
passively transported from outside the estuary. The absence of larvae of most of the marine teleosts that are
abundant in the basins of the Nornalup-Walpole Estuary parallels the situation in the nearby and seasonally
closed Wilson Inlet.
Entrainment and retention of the coastal larval fish assemblage by a short-lived, submesoscale, frontal eddy of the East Australian Current
