The Giant Cuttlefish population in Spencer Gulf is the largest in the world and is highly valued by local residents, the tourism industry and the recreational diving sector. But surveys over the last 13 years has indicated that the northern population has, and continues to, decline markedly - leading to major public consternation.

The Spencer Gulf Prawn Fishery is known as one of the best managed trawl fisheries in the world and is permitted to only land three species, the western king prawn, bugs and southern calamari

A recent SARDI study correlated the observed decline in Cuttlefish abundances with a range of potential factors including: water temperature, weather, pollution (including those from increased shipping activities), predators, prey, habitats, diseases, fishing pressure and tourism. Of these, rainfall was the only factor found to correlate inversely with peak cuttlefish abundance. The study noted the incidental capture of Giant Cuttlefish in the Prawn Fishery but found no clear association between the decline in cuttlefish and fishing intensity. The study noted a positive correlation between trawl effort and the size of the cuttlefish population but this relationship is counter-intuitive and is likely to be coincidental. The evidence therefore does not support an assertion that the recent decline in the abundance of Giant Cuttlefish in northern Spencer Gulf has been caused by prawn trawling or any other forms of fishing.

Nevertheless, due to the low population numbers, all sources of potential mortality of cuttlefish, including that from prawn trawl bycatch, need to be minimized urgently and carefully managed. This project is focused on an attempt to reduce the bycatch of cuttlefish in this fishery using modifications to the trawls used (termed ‘bycatch reduction devices’ or ‘BRDs’). If successful, such BRDs should be suitable for use in locations and at times where cuttlefish bycatches are significant.