15 - Spawning aggregation site in Fiji

Since 2003 SCRFA has worked with the Fisheries Research Division in Fiji, headed by Mr. Aisake Batibasaga. Initially, we conducted interviews around the country to discover what was known about spawning aggregations. We found evidence of many fished aggregations, as well as of declines in catch rates at the more accessible sites. At Naiqoro Passage, set in a marine protected area, our aims were to describe the timing and locations of the species that aggregate, establish a baseline against which to compare possible changes over time, and look at catchment area for the camouflage grouper by tagging and recapturing fish. We are also monitoring annual water temperature and doing outreach on marine conservation in local communities. Since divers pay a levy to dive in Naiqoro Passage to the village that stewards it, there is a strong local interest to protect the Passage from poaching and our results can, amongst other things, help to better plan which day or days enforcement is likely to be most effective.

Studying Naiqoro Passage is a challenge. Weather changes daily and this year we had long spells of wind and rain making access to the site impossible at worst, uncomfortable at best. The site is on an outer reef and exposed to unpredictable tides and currents. The maximum depth and size of the site barely allow us to complete all transects in one day although the area is just small enough to survey in its entirety in two dives with three divers swimming in parallel. The species that aggregate are the camouflage grouper, Epinephelus polyphekadion, brown-marbled grouper, E. fuscoguttatus, blacksaddled coralgrouper, Plectropomus laevis, and squaretailed coralgrouper, P. areolatus (for more details of this study see - SCRFA Newsletter 13 and our 5-part BLOG [www.scrfa.org]).

Numbers of camouflage grouper increased daily over about 10 days to about 300 by the full moon when spawning occurred. The animals then disappeared, literally overnight. A couple of days before spawning we saw females full of hydrated eggs (see photo on front page of newsletter) and males spent much of their time fighting each other. Water temperature was lower (24-25ºC) than at other studied sites (e.g. Solomon Is., Palau, Pohnpei) in the Pacific at the time of spawning. The brown-marbled groupers (maximum about 120 fish) were restricted to a small area to the south of the study site, largely separate from the camouflage grouper and adjacent to the small black-saddled coral grouper aggregation (maximum about 50 fish). After spawning, all but a few of the 300 fish quickly left the site. We were lucky to see one ‘school’ of camouflage grouper, about 30-40 fish at 10 m, moving closely together into the lagoon through the reef passage and away from the aggregation site.

The government is currently discussing recommendations to be formalized in legislation/ regulation by the end of 2011. These include complete protection/no fishing of aggregation sites for all larger reef-associated fishes such as bumphead parrotfish, Napoleon fish, giant sweetlips, sharks and rays. For the groupers, protection would be during 3-5 major spawning months (July-November). In addition reef passages and adjoining promontories, patch reef systems/and outer reef slopes where spawning aggregations occur would be incorporated into Marine Protected Areas and into the FLMMA community-based management network. Protection of these habitats would benefit large reef fishes and mega-fauna such as sharks, sea turtles, rays, manta rays, whales and dolphins etc.

Yvonne Sadovy de Mitcheson
Aisake Batibatasaga
SCRFA and Fiji Fisheries Research Division
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