13 - Fiji: Study

Fiji Spawning Aggregation Baseline Study - A Progress Report

SCRFA and the Fiji Fisheries Department's Research Division have been working in partnership at a well-known spawning aggregation site situated on the island of Kadavu. This site is in a marine protected area established in 2004. It is popular with divers and patrolled by local village stewards although poaching is believed to occur. In addition to Fisheries Research Division staff, staff from the Wildlife Conservation Society and biologists Dr. Rick Nemeth from the University of the (U.S.) Virgin Islands and Dr. Michael Domeier of the Marine Conservation Science Institute, California joined us on the study this summer.

The objectives of this study are to establish the baseline conditions of the aggregation site, in terms of timing of spawning, species, numbers, etc., provide training in aggregation research and monitoring, develop a sampling protocol, and use the project to provide information to local communities that complements other marine conservation and management initiatives in Kadavu. We also introduced this year a small tagging component to determine the catchment area of Epinephelus polyphekadion (or the kawakawa locally) between spawning seasons. An external tag with high retention designed by Dr. Domeier was used.

The field season was conducted over 6 weeks in July and August, 2009, later and longer than in 2008, and during the main spawning season for the three groupers that use the spawning site, according to previously conducted interviews. A total of 40 E. polyphekadion were tagged with yellow tags marked with individual numbers and contact details to the Lami Fisheries (see photos). T-shirts were provided as rewards for returned tags and for the tagging team. Tagged fish ranged in size from 420 to 544 mm total length, all within the mature size range of the species. E. fuscoguttatus and Plectropomus laevis were also observed in good numbers this year. P. areolatus were not seen this year although they were numerous last year during a slightly earlier period.

We paid visits to the coastal communities both north and south of the spawning site, with sevusevu traditional gift of kava (‘yaqona', the dried root of the plant Piper methysticum), to provide information on the tagging project and its relevance the to fishery and marine protected areas, and to invite community members' participation by returning the tags. Discussions were also made addressing issues concerning marine conservation and management.

Several interesting patterns were found by surveying the full extent of the aggregation site. First, the three species peaked in numbers at different phases of the moon. The most abundant species, as last year, was E. polyphekadion which peaked at almost 300 fish. E. fuscoguttatus peaked at about 120 fish, at the same time and a pair-spawn was observed. P. laevis occurred in much smaller numbers (maximum counted on any one day was 34) and peaked at a different time; large males displayed some wonderful colour changes including an intense black/white pattern with white lips while they patrolled high above the substrate among groups of 9-10 fish (probable females). We also noted that the three species were consistently found within specific depth ranges and differed in their occurrence on either side of the channel spawning site; this highlights the need to carefully check the entire aggregation area. A few of the tagged fish remained at the same locations of the study site for at least 2 week after spawning finished and their space use was characterized. Fish behaviour returned to normal shortly after tagging.

Yvonne Sadovy de Mitcheson
SCRFA
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Aisake Batibasaga
Fiji Fisheries Department
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