Abstract. The New South Wales (NSW) government has operated a program of netting beaches for the protection of swimmers and surfers against shark attack since 1937 in Sydney, and since 1949 in Newcastle and Wollongong. The scope and directives of the Shark Meshing Program have remained constant since its inception, with operational modifications in net specifications in 1972, changes in spatial deployment in 1972, 1987 and 1992, and the elimination of winter netting since 1989. This markedly increased meshing effort in 1972, and again in 1987. In the present study, we examine the trends in catch and effort for the period from 1950-1951 to 2009-2010 over this 200-km section of the NSW coast. Significant temporal trends in species, size and sex composition are described herein. Catches were consistently dominated by three shark taxa, hammerhead sharks (Sphyrna spp.), whaler sharks (Carcharhinus spp.) and Australian angel sharks (Squatina australis), although their relative contributions to catches varied over time. Catch per unit effort has significantly declined for five of the most abundant shark taxa over the study period, increasing only for a single taxon, the sevengill shark (Notorynchus cepedianus). Catches of larger, potentially dangerous white sharks (Carcharodon carcharias) and tiger sharks (Galeocerdo cuvier) saw fewer large animals being caught over time. This pattern was not observed across other taxa. Four different monthly trends were observed in landings of the most abundant eight taxa, reflecting differences in the biology of the catch species. The current study also provides useful information on catches and sizes of grey nurse (Carcharias taurus) and white sharks before and after their protection in NSW waters in 1984 and 1998, respectively.

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Samples of 16 key fish species targeted by oceanic prawn trawlers and oceanic and estuarine beach seiners in southeastern Australia were measured for up to 10 morphological dimensions that included: total (Wt) and eviscerated weights (EWt); total (TL), fork (FL), natural (NL), standard (SL), dorsal standard (DSL), and anal standard lengths (ASL); and maximum body height (MH), width (MW), and girth (MG). All partial lengths were indexed against TL to provide linear relationships and, where there were sufficient data, tested for intra-specific sexual dimorphism. Nearly all species that were sexed demonstrated at least some morphological divergence, and especially for transverse measures; probably owing to different reproductive conditions. Sex-specific or combined regressions of DSL and ASL and transverse measures versus TL were used to identify the most appropriate: (1) partial length for compliance purposes; and (2) mesh sizes and configurations for the different fishing gears M05052;

In a 2‐year grow‐out trial, triploid Sydney rock oysters, Saccostrea commercialis (Iredale & Roughley), from two initial size grades grew faster (in terms of both mean whole weight and shell height) than the equivalent initial size grades of sibling diploids (P < 0.05). Small size grade triploids caught up with and had significantly heavier (P < 0.05) final whole weights than large size grade diploids after a 2‐years grow‐out period. The initial size grade had a significant effect on final mean whole weight and shell height for both ploidy types. After the 2‐years grow‐out trial, the final mean whole weights (but not shell heights) of small and large diploids (35.8 ± 0.6 g and 39.4 ± 0.5 g, respectively) were significantly different (P < 0.05). Small and large triploids grew at a similar rate for the first 18 months despite the significantly (P < 0.05) heavier final mean weight of large grade triploids (48.4 ± 0.8 g and 61.2 ± 0.7 g, respectively). The effect of the initial size grade on subsequent growth of both diploid and triploid oysters which was demonstrated in the present study is of significant commercial value to hatchery and nursery operators as well as growers of single seed oysters. In addition, small‐grade triploids appeared to be more valuable in terms of potential growth rate than all diploid grades. There was no significant difference in the final percentage triploidy between small and large grade triploids. A large proportion of diploid/triploid mosaicism was detected in adult oysters.