Regionally endangered, locally abundant

Story & Photos By John Claydon, PhD & Marta Calosso, MS, MA – TCI Nassau Grouper Project leaders

Go on any SCUBA dive or snorkel trip in the Turks & Caicos Islands and you would be very unlucky not to see a Nassau grouper or two. It is no exaggeration to say that there is nowhere else in the world where you encounter this species so frequently. When they see you from a distance, they usually remain quite stationary except to turn their heads to track your movement as you swim by. Often they can be curious, and they may approach divers — however, this is typically a sign that the fish is accustomed to being fed which should not be encouraged.

It is also quite easy to find them on a dinner plate: many restaurants will offer this locally caught fish, usually listed simply as “grouper” on the menu. We take this for granted, but in some other countries Nassau groupers have become so rare that it is illegal to catch them. In fact, the species is considered endangered by the International Union for the Conservation of Nature, the organisation tasked with assessing species’ risks of extinction.

Nassau grouper is usually considered to be a coral reef fish, but that is a little misleading. When grouper spawn, eggs are released high above the substratum; eggs then hatch into larvae and spend about forty days in the water column drifting offshore and potentially dispersing long distances in the currents. Eventually, once they have grown about an inch long and become capable swimmers, larvae are ready to swim back to shallow areas and settle, but typically the habitats they choose are not reefs, but seagrass or algal areas.
In the TCI, early juvenile Nassau grouper often use discarded conch shells and “blowout” ledges — the shelter formed by exposed roots and rhizomes in seagrass beds. After spending about a year in their early juvenile habitats, Nassau grouper migrate to shallow patch reefs, and then to deeper reefs, where they become reproductively mature at four to eight years of age. While some reef fishes breed year-round, Nassau grouper has a very short spawning season of two to three months only, which in the TCI runs from December to the end of February and synchronises with a phase of the moon. Nassau grouper breeding can be spectacular: they form aggregations of thousands (reportedly up to one hundred thousand) with individuals capable of migrating over sixty miles to spawn at the same location year after year.
Unfortunately, the demise of Nassau grouper throughout the region is directly linked to fishing spawning aggregations. Large numbers of big fish found at the same time and place each year are attractive targets for fishers, but such fishing has rarely been sustainable, and sometimes an aggregation of tens of thousands can be “fished out” in a few years. When this happens, the local population crashes, the fishery is no longer viable, and your chances of seeing one on a dive are close to zero. Even worse, there are few signs of populations recovering.
Fortunately, the TCI has been quite lucky compared to rest of the region: commercial and export fisheries have focused on lobster and conch, and although most fishers know about the aggregations, they do not fish them much. The single most effective management strategy is to prevent such fishing, and although the pressure is currently low, it does appear to be growing. Consequently, as a proactive measure, Nassau grouper will be protected during their breeding season (December 1 to February 28) through Amendments to the Fisheries Protection Ordinance introduced earlier this year. During this closed season, Nassau grouper will be off-limits to fishers and off the menu in restaurants, in much the same way as the closed season for spiny lobster.
The social and ecological dynamics of the Nassau grouper fishery and the species’ ecology in the TCI is the focus of an ongoing research collaboration between DEMA, the Reef Environmental Education Foundation, Oregon State University, and Scripps Institution of Oceanography, UC San Diego. Our goals are to better understand the complex dynamics of the Nassau grouper fishery in the TCI and to document the status of spawning aggregations and the stocks in general, so that the TCI can continue to enjoy its unique status where fishers can still catch groupers, tourists can still see them in the water, and everyone can enjoy eating them.
The project was initiated in 2014 through a grant from The Flagship Species Fund, Fauna and Flora International which enabled us to spend three months all over the TCI conducting interviews with fishers and various stakeholders, monitoring dock landings, collecting biological samples, and tagging Nassau groupers on SCUBA. We are very grateful for the support provided by Big Blue Unlimited, The School for Field Studies, MV Glen Ellen, and a friend of the Turks & Caicos Reef Fund. Special thanks go to the community of South Caicos.