Baited video, but not diver video, detects a greater contrast in the abundance of legal-size target species between no-take and fished zones

Inherent differences between baited remote video versus diver-operated video survey methodologies may influence their ability to detect effects of fishing. Here the ability of no-take zones (NTZs) to provide protection for legal-sized fish from targeted species within the Ningaloo Marine Park (NMP) was assessed using both baited remote underwater stereo-video (stereo-BRUV) and diver operated stereo-video (stereo-DOV). The relative abundance of legal-sized individuals of three recreationally targeted fish species, spangled emperor Lethrinus nebulosus, chinaman cod Epinephelus rivulatus and goldspotted trevally Carangoides fulvoguttatus, were examined using both methodologies inside and outside six NTZs across the NMP. Stereo-BRUVs found positive effects of protection on the relative abundance of legal-size C. fulvoguttatus and L. nebulosus in NTZs. Stereo-DOVs, however, did not detect any differences in relative abundances and sizes of these species between areas opened and closed to fishing. These contrasting results suggest that choice of sampling methodology can influence interpretations of the ability of NTZs to provide adequate levels of protection for target species. Thus it is suggested to further investigate the ability of stereo-BRUVs and stereo-DOVs to observe differences in the abundance of targeted species inside and outside of NTZs for the long-term monitoring of the NMP.

Pseudorhabdosynochus inversus sp. nov. (Monogenea, Diplectanidae) from the halfmoon grouper Epinephelus rivulatus (Perciformes, Serranidae) off New Caledonia

Pseudorhabdosynochus inversus sp. nov. is described from three specimens found in a halfmoon grouper, Epinephelus rivulatus, from the external slope of the barrier reef, New Caledonia, South Pacific. The new species is characterised by the structure of its sclerotised vagina, which resembles that of P. epinepheli (Yamaguti, 1938) but has its primary chamber inverted, and by its measurements. The diplectanid fauna of E. rivulatus shows the same pattern as in other groupers, probably belonging to a clade in which fish species harbour both an abundant species of the ‘Pseudorhabdosynochus cupatus group’ (here P. calathus Hinsinger et Justine, 2006) and a rare species (here P. inversus).