13 - Indonesia

Aggregation Fishing and Tag-Recapture in Ayau, Raja Ampat, Indonesia

The Nature Conservancy- Indonesia (TNC) and Conservation International-Indonesia (CI) recently conducted a Packardfunded training workshop to assess grouper spawning aggregations at Ayau, Raja Ampat, Indonesia, currently under a system of traditional management based on local marine tenure. The cruise (8th to 17th October) was initiated to train local TNC and CI staff, local community members and government partners (Department of Fisheries-West Papua and Department of Nature Conservation-West Papua) in conventional and acoustic tag-recapture and fisheries monitoring, and demonstrate how this information can be used in fisheries management and MPA design. In Raja Ampat, grouper (fish) spawning aggregations (FSA) have been targeted by local fishers for the Southeast Asia-based live reef food fish trade (LRFFT) since the 1980s.

Nine potential FSA sites were identified during previous surveys. Based on advice from local fishers, one was selected for the training. This site was confirmed as an FSA for brown-marbled grouper Epinephelus fuscoguttatus and squaretail coralgrouper Plectropomus areolatus from observations of courtship, temporary colour changes and the presence of many gravid females. In addition, aggregations of bigeye trevally Caranx sexfasciatus, barracuda Sphyraena sp., Humpback unicornfish Naso brachycentron, Longface emperor Lethrinus olivaceus, Ringtail surgeonfish Acanthurus blochii and sea chub Kyphosus sp. were observed. Large (≥1 m) Blacksaddled coralgrouper Plectropomus laevis and Humphead wrasse Cheilinus undulatus were also seen although they were not confirmed to be spawning aggregations. Spawning was confirmed for C. sexfasciatus, with frequent colour changes and courtship, and a spawning rush observed at ca. 1600 hr, 2 days prior to new moon.

At the FSA, fishery trainees and participants tagged 40 P. areolatus, including 20 with acoustic tags, to examine sex-specific residency and movement. Ten acoustic receivers will remain moored in and around the FSA site until March 2010, including three aggregation months. Timing and specific locations of aggregations are kept confidential to reduce the potential for increase in commercial exploitation.

Provincial government representatives and local stakeholders also participated in catch-per-unit-effort (CPUE) data collection from the FSA fishery. Over 5 days, 39 local FSA fishers, who fish for the commercial Asian live reef fish market, used hook-and-line to remove 564 P. areolatus from the FSA, with a CPUE of 0.7 fish per hour per fisher Two acoustically tagged fish and one conventionally tagged fish were re-captured and rereleased, including one that was re-captured twice.

Underwater visual census (UVC) identified the distribution and abundance of fishes on the FSA site. On the final cruise day, monitors counted ca. 80 E. fuscoguttatus, and ca. 300 P. areolatus. Combined CPUE data and UVC monitoring suggest more than 800 P. areolatus were present during the aggregation monitoring period, with >70% of those removed for the LRFFT. Findings will be shared with the local community, stakeholders and relevant fisheries agencies to advise them further on the vulnerability of this and other FSAs to commercial fishing for the LRFFT.

Kevin L. Rhodes
Pacific Marine Science and Conservation
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Joanne Wilson
The Nature Conservancy-Indonesia
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Chris Rotinsulu
Conservation International
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