Ichthyoplankton assemblages associated with pink snapper (Pagrus auratus) spawning aggregations in coastal embayments of southwestern Australia

摘要

Pink snapper (Pagrus auratus) form spawning aggregations during the austral spring/summer in three adjacent, sheltered, coastal embayments in southwestern Australia (Cockburn Sound, Warnbro Sound and Owen Anchorage). Larval fishes were sampled in these embayments, as well as in the more exposed adjacent waters of Five Fathom Bank, to ascertain which teleost species utilised these areas for spawning concurrently with P. auratus. Obliquely towed bongo nets (500 μm mesh) were used to collect icthyoplankton in November 2007 over three days during the new moon period when spawning of P. auratus is known to peak. A total of 13 270 larvae from 30 teleost families was collected with an overall mean larval fish concentration of 1.91 m -3 (± s.e. 0.28). Larval fish assemblages were significantly different in each of the three embayments and Five Fathom Bank, reflecting the degree of shelter, water-circulation patterns and associated benthic habitats. The highest larval fish concentrations were recorded in Cockburn Sound (3.69 m -3 ± s.e. 0.05) and the lowest along Five Fathom Bank (0.16 m -3 ± s.e. 0.02). P. auratus larvae were only present in samples from the three embayments. The most abundant larvae were those of the Australian anchovy (Engraulis australis), which occurred predominantly in Cockburn Sound and, to a lesser extent, Owen Anchorage. The most ubiquitous larvae included the longspine dragonet (Callionymus goodladi) and leatherjackets (Monacanthidae). This study provides circumstantial evidence that eggs and larvae of P. auratus and other teleosts are retained in the sheltered waters of Cockburn and Warnbro Sounds during spring/summer.