Distribution, relative abundance and size composition of the threatened serranid Epinephelus daemelii in New South Wales, Australia.

Journal of fish biology

PubMedID: 23902312

Harasti D, Malcolm H. Distribution, relative abundance and size composition of the threatened serranid Epinephelus daemelii in New South Wales, Australia. J Fish Biol. 2013;83(2):378-95.
The aim of this study was to undertake baseline surveys on the distribution, relative abundance and total lengths (LT ) of a threatened epinephelid species, black cod Epinephelus daemelii, in New South Wales (NSW), Australia, their westernmost distribution. Diving surveys at 83 sites where E. daemelii were expected to occur were undertaken from 2009 to 2011 using 45?min roving diver counts. Sites were spread through northern NSW, including Lord Howe Island (LHI). Individual fish were measured using stereo-video, enabling accurate length measurement. Surveys were repeated at a sub-set of sites to assess temporal variation across days, seasons and years. A total of 117 E. daemelii were recorded during baseline surveys, occurring at 42% of the surveyed sites. Across all surveys, the highest numbers recorded (14-18 individuals at a site) were at the outer Solitary Islands and Fish Rock (Smoky Cape). Fewer E. daemelii were found southwards, but two sites in the Port Stephens-Great Lakes Marine Park had consistent numbers (three to six) over four annual surveys. Only 12 E. daemelii were recorded from eight of the 18 sites at LHI. The numbers observed at re-surveyed sites were generally stable over years. There were latitudinal and cross-shelf differences in LT . Individuals in the north were found to be significantly larger than those further south, and fish offshore were significantly larger than those inshore. The largest measured fish was 135?cm, smaller than the maximum LT (c. 170?cm) recorded for this species. The smallest fish was 26?cm. Overall, it is considered that the abundance of E. daemelii is low compared to anecdotal data even though they have been protected for c. 30?years in NSW. These findings provide an essential benchmark to assess ongoing status and response to protective management.