|Scientific Name:||Epinephelus striatus|
|Species Authority:||(Bloch, 1792)|
Epinephelus striatus (Bloch, 1792)
|Red List Category & Criteria:||Endangered A2ad ver 3.1|
|Assessor/s:||Cornish, A. & Eklund, A.-M.|
|Reviewer/s:||Garcia-Moliner, G. & Sadovy, Y. (Grouper & Wrasse Red List Authority)|
Epinephelus striatus is assessed as Endangered based on a high rate of decline in population size. It is estimated that the population has declined by approximately 60% over the last three generations (27-30 years).
|Range Description:||The Nassau Grouper is found from Bermuda and Florida throughout the Bahamas and Caribbean Sea. Heemstra and Randall (1993) indicate a second subpopulation lying along the coast of Brazil, roughly from Forteleza to Rio de Janeiro. However this may be an error, as there do not appear to be any specimens or verifiable photographs of the Nassau grouper from Brazil (Heemstra, pers. comm. 2001, Moura 2001).|
Native:Anguilla; Antigua and Barbuda; Aruba; Bahamas; Barbados; Belize; Bermuda; Cayman Islands; Colombia; Costa Rica; Cuba; Curaçao; Dominica; Dominican Republic; French Guiana; Grenada; Guadeloupe; Guatemala; Guyana; Haiti; Honduras; Jamaica; Mexico; Montserrat; Netherlands Antilles (Curaçao); Nicaragua; Panama; Puerto Rico; Saint Kitts and Nevis; Saint Lucia; Saint Vincent and the Grenadines; Suriname; Trinidad and Tobago; Turks and Caicos Islands; United States (Florida); United States Minor Outlying Islands; Venezuela; Virgin Islands, British; Virgin Islands, U.S.
|FAO Marine Fishing Areas:||
Atlantic – western central
|Range Map:||Click here to open the map viewer and explore range.|
Most time series landings/CPUE data sets show some yearly fluctuations and even large ones, but not order of magnitude fluctuations. However, Table 16 in Sadovy and Eklund (1999) of commercial landings in the US showed order of magnitude variations from 1986 to 1988 when total landings in pounds were 15,633, 0, 4,737 respectively. The data has been checked and indeed, very few Nassau were caught in 1987, and for no apparent external reason (Eklund, pers. comm., March 2001). As the Nassau grouper is long-lived and relatively sedentary this is rather surprising.
Current population size is estimated at >10,000 mature individuals. It is estimated that a population decline of 60% has occurred over the last three generations (27-30 years). Ideally, the percentage decline (from the best available data, i.e., landings, CPUE, spawning aggregation size) would be applied to estimates of the original Nassau subpopulation within each country for which the decline applies. This would be done for all countries and the overall decline would be the percentage difference between the original global population size and the current one. Unfortunately, estimates of country stock size are rare. Therefore, past declines were weighted by coral reef area (rather than population size) to give an overall decline figure. This method assumes that pristine densities of Nassau grouper were the same at all localities. This is probably not likely to have been the case but it enables a single figure to be derived, which is likely more representative of the global situation than the alternative, which would be to say that the decline lies between 55 and 99.5% (the lowest and highest documented decline rates).
From the available data and most recent reports, Nassau subpopulations are likely to either be stable (e.g., the U.S.) or in decline (e.g., Cuba, Belize). Overall, it seems very likely (80-100%) that overall, the global population of Nassau grouper will continue to decline over the foreseeable future.
There is no evidence of distinct subpopulations of Nassau grouper based on genetic work (mtDNA and microsatellites) of fish sampled from a number of sites in Florida, Cuba, Belize and the Bahamas (Sedberry et al. 1996). Therefore, it is considered that there is only one subpopulation with all individuals in it, that the population is not severely fragmented. There is no evidence of extreme fluctuations in the number of locations or subpopulations.
|Habitat and Ecology:||
Occurs to at least 130 m and is most abundant in clear water with high relief coral reefs or rocky substrate (Sadovy and Ekland 1999) Post-settlement fish inhabit Laurencia macroalgal clumps, seagrass beds and coral (Eggleston 1995, Dahlgren 1998).
Generation time is estimated at 9-10 years, based on average fish size from an unexploited aggregation in Belize and the growth curve from five Cayman Island spawning aggregations (Sadovy and Eklund 1999).
Nassau Grouper are fished commercially and recreationally by handline, longline, fish traps, spear guns and gillnets. Aggregations are mainly exploited by handlines, or by fish traps, although gillnets have recently been used in Mexico. Declines in landings, catch per unit effort (CPUE) and, by implication, abundance have been reported throughout its range and it is now considered to be commercially extinct in a number of areas (Sadovy and Ekland 1999). The fact that much of the catch in many areas comes from spawning aggregations (Sadovy and Eklund 1999) is also worrying given that targeted aggregations have evidently collapsed in many countries.
Suitable habitat for the Nassau grouper is also likely to be in decline. Of the estimated 20,000 km² of coral reef in the Caribbean, 29% is estimated to be under high risk of degradation from human activities, 32% is at medium risk and 39% is at low risk (Bryant et al. 1998). Although the Nassau grouper also inhabits rocky reefs, these are unlikely to be able to compensate for the loss of quality coral reef habitat.
There has been a complete ban on the fishing of Nassau grouper in the US federal waters since 1990. This includes federal waters around Puerto Rico and the U.S. Virgin Islands. There is also a ban on U.S. state waters. The species is a candidate for the US Endangered Species List.
In Mexico in 1997, the fishery authority completely banned fishing Nassau grouper "during spawning aggregations" (December to February) (Aguilar-Perera, pers. comm. 2001). This regulation is believed to still be in place.
In the Bahamas, three spawning aggregation sites, High Cay of the coast of Central Andros and two sites off the east coast off Long Island were protected by law from 17 Dec 1999 to 24 February 2000. In addition, fishing for Nassau grouper was banned throughout the Bahamas from 12-26 February 2000 (M. Braynen press release, February 2000). As of 2003, there is no enforcement (other than voluntary at one site) of fishery bans on aggregations at any site in the Bahamas (Sir Nicholas Nuttall, pers. comm.).
In Belize, spawning aggregation sites were open to fishing on a rotational basis but in at least one recent case (Glover's Reef in 1999/2000), there was no enforcement of a fishing ban and it was fished (Sala and Ballesteros 2000). As a result of growing concern, all Nassau grouper aggregations were closed to fishing at the end of 2002 in Belize.
In the Cayman Islands, there are three main ('traditional') grouper 'holes' in the Cayman Islands which only residents are allowed to fish during spawning season. Only line fishing is permitted. This legislation appears to have come into effect in 1978 (Phil Bush, pers. comm. 2001). Recognizing further declines new legislation is to be introduced in January 2003 to protect Nassau grouper at designated spawning areas (Phillippe Bush pers. comm.).
In addition, it is forbidden to fish for groupers during spawning seasons in the Dominican Republic, there is a moratorium on fishing for Nassau groupers in Bermuda and a quota system was introduced for the capture of Nassau's in Cuba (see Sadovy and Eklund 1999).
The degree to which the Nassau grouper receives protection through no-take marine protected areas is not known.
The available evidence indicates that spawning aggregations are extremely important to maintenance of Nassau grouper populations, most of the data needed to improve the accuracy of this assessment in the future would be on the current status and importance of these aggregations. Information on the following would be of great value:
1) Are traditional aggregation sites special or can aggregations form in new areas ?
2) Does reproduction in the Nassau grouper only occur in spawning aggregations and if this is the case, do mature individuals reproduce each year and do they always use the same site ?
3) There are a number of traditional aggregation sites that have reportedly disappeared (see Sadovy and Eklund 1999) that do not appear to have re-visited in recent years. Assessing the health of Nassau grouper populations in the future would be greatly improved by annual monitoring of as many traditional aggregation sites as possible. This would include checking for the possible formation of aggregations in the vicinity of traditional sites where no aggregation currently occurs.
It would also be helpful to know the degree to which Nassau groupers receive effective protection in marine protected areas of the Caribbean.
|Citation:||Cornish, A. & Eklund, A.-M. 2003. Epinephelus striatus. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. <www.iucnredlist.org>. Downloaded on 20 May 2013.|
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