As highlighted above, flooding in NSW rivers pushes a suite of important species to sea, including mature School Prawn (SP), juvenile Mulloway, and also Eastern King Prawn (EKP). Trawl fishers can enjoy good catches of large/valuable SP following these flood events (which usually occur around March), but the abundant School Prawn is frequently matched by abundant juvenile Mulloway in trawlable areas (Mulloway is overfished in NSW). In recent years, bycatch of juvenile Mulloway has led to spatial closures in the trawl fishery, which mean that inshore trawlers cannot access valuable School Prawn when productivity and demand for product are at their highest.
New South Wales has network of permanent trawling closures along the coast, many of which are present in the inshore areas adjacent to the mouths of estuaries in northern New South Wales. These closures were initiated collaboratively by DPI-Fisheries and industry to improve offshore yields of Eastern King Prawn by limiting harvest on smaller Eastern King Prawn in inshore waters. In the context of the above information, the Professional Fisherman’s Association (PFA) and DPI-Fisheries managers requested an evaluation of these permanent closures, in terms of 1) whether they afford protection for juvenile Mulloway during periods when they are flushed from the river; and 2) whether School Prawn occur in these closure areas (without Mulloway) following floods which could be exploited when other areas are closed. Consequently, managers and fishers are seeking this scientific data to 1) put bycatch levels of juvenile Mulloway into a broader context of potential impact and importance to the stock; and 2) underpin a suite of complementary management arrangements which give regard to both maintaining trawl catches and protecting juvenile Mulloway.
The NSW Department of Primary Industries-Fisheries has outlined the results of a four-year trawl survey (2017-2020) aimed at evaluating spatial management provisions within the NSW Ocean Trawl Fishery (OTF) and the potential for these to be adapted to deal with tactical challenges associated with Eastern School Prawn (Metapenaeus macleayi) harvest and Mulloway (Argyrosomus japonicus) bycatch following floods in northern NSW.
This was the first evaluation of one of the most extensive closure networks used in a penaeid trawl fishery and highlights the unquantified impact of other inshore spatial management arrangements within NSW (e.g., Marine Protected Areas) on species that trawl fisheries interact with.
The closure network was implemented at a time when the NSW OTF fleet was much larger. However, while not specifically intended in their implementation, the closure network provides considerable protection from fishing mortality for the broader assemblage of species which are impacted by the activities of the NSW OTF. Coupled with the fact that the closures were spearheaded by industry, this adds to the sustainability credentials for the fishery, and the social license which supports its operation.
More information: Matt Taylor firstname.lastname@example.org