The Development and Introduction of By-catch Reducing Technologies in Three Australian Prawn-Trawl Fisheries
Authors: Kennelly Steven J. 
Published: October 2011

Three tasks are usually required to introduce new technologies that reduce by-catches in commercial fisheries: (i) identify and quantify the particular by-catch issue that requires the new devices; (ii) develop and test the devices; and (iii) implement the devices into industry by voluntary
acceptance and/or legislation. To solve by-catch problems in prawn-trawl fisheries in three regions of Australia, different approaches have been followed with varying success, and their comparison identifies an ideal framework under which such problems can be resolved.In northern Australia’s
prawn-trawl fisheries, the main by-catch issues involved turtles and the discard of a large diversity offish species. To quantify these issues, data were obtained from research vessels, industry logbooks and samples from fishers. Before and during this work, modified gears were developed and
tested in a flume tank and in the field using research vessels and, to a lesser extent, commercial vessels. Next, a separate project was established to encourage acceptance of the new technologies by industry and involved workshops, newsletters and a library that lent out various by-catch
reducing devices to fishers. Voluntary acceptance of the new gears is currently estimated to be 50‐80% in some ports and 0‐20% in others, and a three-phase plan for their legislation is due to occur between 1999 and 2002.In New South Wales, the main by-catch issue was the
large number of undersize fish discarded by prawn trawlers as they caught prawns and other species of retained by-catch. Firstly, observer programmes on commercial vessels were used to identify and quantify size- and species-specific by-catches. Then, modifications to fishing gears that reduced
the identified problematic by-catches were developed and tested on chartered commercial fishing vessels. Next, involving fishers in this work (and workshops, posters, videos, etc.) led to the voluntary acceptance of the new modifications by the majority of fishers (estimated to be 100% in
some fisheries and 50‐100% in others). Finally, the new devices were made mandatory by legislation in several fisheries, with the others to follow within 12 months.In South Australia’s Gulf St. Vincent, the chief by-catch issue mainly came from the prawn-trawl industry itself
and concerned the by-catch of small prawns and fish. The approach used was to begin gear-development research without any formal quantification phase. After preliminary trials by industry, only five days of formal tests of new devices were required to recommend a design that was optimal for
industry’s (and management’s) requirements. Within two weeks of the completion of the field trials, 100 of the industry was using this new gear voluntarily and its legislation is planned to occur within the next few years to ensure continued compliance.The simple pattern that
emerges from these examples is that the sooner industry is fully involved in all stages of the work (driving the issue, quantifying it, developing devices and implementing them), the sooner and more complete is the voluntary acceptance of by-catch reducing fishing technology, and the more
painless is the implementation of the relevant legislation.