 Using TEDs to reduce sea turtle by-catch in commercial fisheries in Sabah, Malaysia
The primary goals of this project were to improve the sustainable livelihoods and building the capacity of the local fisherfolk communities to enable them i) to undertake much more sustainable fishing efforts, particularly among the local communities operating out of Sandakan, Sabah, Malaysia, and ii) to reduce the loss of marine biodiversity, especially of the green turtle Chelonia mydas, listed as Endangered by the IUCN Red List. The project aimed to demonstrate the impact of commercial trawling on adult and juvenile endangered sea turtle populations off the east coast of Borneo, and also determine its potential impacts on marine diversity and on the sustainable livelihoods of local fisherfolk communities, while developing potential mitigation options at the operational and management levels.  This project was developed in partnership with the Sabah Department of Fisheries, and is already providing the data upon which the Government can base further fishery practice controls to conserve marine turtles, be it through the use of excluder devices, or possibly seasonal and/or temporal closures. The project is the first of its kind to receive the blessing of the Sabah Fisheries Department as a first step in determining 1) the level of bycatch and 2) the opportunities for introducing TEDs on a voluntary basis (at first) and subsequently as a Government mandate. The reduction in the bycatch of endangered marine turtles and other key taxa is a key conservation objective of many global marine biodiversity programmes, besides being identified as one of the focal species groups (turtles, cetaceans, birds and sharks) of marine bycatch reduction efforts. Fishing behaviour and aspects of fishing activity which could have impacted catch and bycatch composition were not found to be substantially different. Often, amongst trials of these type, there is a degree of hesitance in accepting results which often contradict initial impressions. Graphic depiction of results is often overridden by statistically robust analyses, and personally impressions are found to be biased based on (often) preconceived opinions. The setting time – the time of day at which nets were deployed – was not found to differ significantly between trials with TEDs and trials without TEDs. Fishing vessels operating with TEDs set their nets at night 64.2% of the time (in two deployments around eight pm and two am) while those without TEDs set their nets at night 61.5% of the time (similarly in two deployments around eight pm and two am). Trawl depth – the average depth in waters through which the net was towed – was not found to differ significantly between trials with TEDs and trials without TEDs. Trawl duration – the length of time each net was ‘soaked’ – was the only aspect of the fishing that varied to any notable extent, with trials using TEDs being slightly shorter than those operating without TEDs. An analysis of variance of the individual trawl patters concluded statistically that tows with TEDs lasted approximately 8 minutes shorter on average than those operating without TEDs. Trawl duration was, however, found to have more profound implications, irrespective of its impact on catch and bycatch rates. Simply put, these long trawl durations will undoubtedly drown any turtle they capture. Turtles are air-breathing reptiles, and able to hold their breaths for 1-2 hours under normal circumstances. Caught in fishing nets these abilities are compromised, and breath-holding drops to less than 1 hour. For this reason trawl durations are recommended to last < 1 hour to be turtle-friendly in TED-compliant nations.  These fishing trials were conducted over an 18-month fishing period, with trials both in the monsoon and the non-monsoon seasons. There was a lack of geographical variation across both set of fishing trials, which showed concentrations of activity to the south off the mouths of the Sandakan bay and upper Kinabatangan river mouth, down to the lower Kinabatangan river mouth and as far as Kg. Tangau; and to the north of Sandakan as far as Kg. Gum Gum and Terusan. Interestingly, few among both groups of fishers elected to fish in the vicinity of the Turtle Islands Park, a marine protected area, as depicted by the dearth of points. It appears that there was no significant variation in fishing behaviour through the use of TEDs, except for the slightly longer trials in vessels operating without TEDs (by only some 8 minutes over five and a half hours). Thus, so long as trials were conducted in a similar manner in similar places (invariably vessels operated in pairs and covered similar fishing grounds), the evaluations of catch composition and quality and bycatch and debris exclusion rates should be directly comparable with no introduced bias. It is a measure of credit to the fishers who participated in these trials, and the impartiality of the observers, that this is so.
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Posted on: Wednesday, February 25, 2009