Research Informs Legislative Change in a Marine Turtle Fishery
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Biodivers Conserv DOI 10.1007/s10531-015-0900-1 ORIGINAL PAPER Protecting the breeders: research informs legislative change in a marine turtle fishery 1 2 Thomas B. Stringell • Wesley V. Clerveaux • 1 2 Brendan J. Godley • Quinton Phillips • 1,3 1,3 Susan Ranger • Peter B. Richardson • 3 1 Amdeep Sanghera • Annette C. Broderick Received: 12 September 2014 / Revised: 20 February 2015 / Accepted: 4 March 2015 Ó Springer Science+Business Media Dordrecht 2015 Abstract Marine turtles are sensitive to harvesting because of life-cycle traits such as longevity, late maturity and natal philopatry. The take of nesting females is of conservation concern because they are key to population maintenance and has led to global efforts to protect this life stage. In the Turks and Caicos Islands (TCI; a UK Overseas Territory in the Caribbean), previous turtle fishery legislation protected nesting turtles on the beach but not in the water, where turtles over a minimum size were subject to legal take. In a 2-year study, we undertook nesting beach and in-water surveys, molecular analyses, satellite tracking and collation of fisheries landing data to investigate the populations of green (Chelonia mydas) and hawksbill (Eretmochelys imbricata) turtles in the TCI and its turtle fishery. Adults were frequently taken in one of the region’s largest legal and artisanal turtle fisheries. We suggest that nesting populations in the TCI, which contain genetically unique haplotypes, have diminished since the 1980s, likely as a result of the harvest of adults. Using these multiple lines of evidence, we highlight the inadequacies of the former fishery regulations and propose specific legislative amendments, which, as a result of this study, were implemented on 1 July 2014 by the TCI government. With good enforcement, these measures will protect adults breeding in the TCI and those from nesting rookeries in the region that use the waters of the TCI, improve the management of this fishery, and safe- guard fisher livelihoods. Communicated by Angus Jackson. & Thomas B. Stringell [email protected] Annette C. Broderick [email protected] 1 Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Cornwall Campus, Penryn TR10 9FE, UK 2 Department of Environment and Maritime Affairs, South Caicos, Turks and Caicos Islands 3 Marine Conservation Society, Ross-on-Wye, Herefordshire HR9 5NB, UK 123 Biodivers Conserv Keywords Turks and Caicos Islands Á UK overseas territories Á Marine turtle harvest Á Nesting phenology Á mtDNA haplotypes Á Satellite tracking Introduction Fishing has played a dominant role in almost every marine ecosystem, with numerous species overexploited and greatly reduced (FAO 2010; Myers and Worm 2003; Pauly et al. 2005). Marine turtles are no exception, and their reduction from historical abundances is widely known, particularly in the Caribbean region (Jackson et al. 2001; McClenachan et al. 2006). Marine turtles are sensitive to exploitation because they are long-lived, late maturing, exhibit natal philopatry, lay eggs on land and, in most species, their life-cycle involves migrations and distinct life stages where habitats and locations are partitioned (Crouse et al. 1987; Crowder et al. 1994; Fitzsimmons et al. 1997; Heppell and Crowder 1996). This results in genetically differentiated populations that occupy broad marine regions—often entire ocean basins—and cross international boundaries (Bowen and Karl 2007). Conservation of such wide ranging species is, therefore, complex and may often involve a multitude of stakeholders and nations that have differing regulatory and man- agement frameworks, and cultural, traditional and economic values (Blumenthal et al. 2007; Frazier 2002; Hawkes et al. 2012). Despite this complexity, management at the country level rather than multilateral agreements has been suggested as one of the most important steps towards regional conservation (Moncada et al. 2012; Richardson et al. 2013b). Exploitation of nesting females from natal rookeries can quickly reduce populations (Kittinger et al. 2013; McClenachan et al. 2006). Protection of nesting rookeries has con- sequently been one of the tenets of marine turtle conservation and has led to the recovery of once exploited populations (Broderick et al. 2006; Chaloupka et al. 2008). There are, how- ever, many rookeries that have not been entirely extirpated but remain small, particularly in the Caribbean (McClenachan et al. 2006). Here, there is a call for a renewed conservation focus on remnant nesting populations, especially for the hawksbill turtle (Eretmochelys imbricata), which is considered critically endangered by the International Union for Con- servation of Nature (IUCN) (McClenachan et al. 2006; Mortimer and Donnelly 2008). In- deed, LeRoux et al. (2012) call for the genetic characterisation of smaller and unsampled hawksbill turtle rookeries in the wider Caribbean and suggest that all hawksbill turtle rookeries be treated as distinct management units, because of their potential to maintain regional genetic diversity. Similarly, Shamblin et al. (2012) call for further investigation of small, remnant green turtle (Chelonia mydas) rookeries in the Caribbean to further elucidate their importance in regional stock demographic connectivity. In several Wider Caribbean nations, legislation regulating the remaining legal turtle fisheries typically utilises minimum size limits that prohibit take of small juveniles and permit the take of larger size classes, such as adults (Brautigam and Eckert 2006; Fleming 2001; Humber et al. 2014; Richardson et al. 2006b). Such regulations were inherited from fin-fisheries legislation where minimum landing size is commonly used, but for long-lived species such as marine turtles, protection of large juveniles and reproductive adults is likely critical to their recovery (Carr et al. 1982; Crouse et al. 1987; Crowder et al. 1994; Heppell and Crowder 1996). Four of the six UK Overseas Territories in the Wider Car- ibbean Region still permit the take of turtles (Godley et al. 2004b). Of these, the Cayman 123 Biodivers Conserv Islands recently amended its legislation to protect larger turtles by establishing a maximum size limit and an extended closed season (Blumenthal et al. 2010; Cayman Islands Government 2008). Prior to 2014, the Turks and Caicos Islands (TCI) turtle fishery was regulated by the 1997 Fisheries Protection Ordinance (Government of the Turks and Caicos Islands 1998), which prohibited the take of green turtles and hawksbill turtles below the minimum size limit of ‘20 inches in length measured from the neck scale to the tail piece’ or a weight of at least 20 lbs. There were no seasonal restrictions to the harvest (closed seasons) and fishers were legally entitled to remove an unlimited number of turtles larger than these minimum size limits if caught at sea at any time of the year. Turtles of other species could only be taken if they weighed at least 20 lbs. Any take of turtle above the low-water mark (i.e., nesting females) was prohibited, so too was the possession, purchase or sale of ‘laid’ turtle eggs (see Richardson et al. 2006b for review). Little was known about the magnitude or seasonality of the green turtle and hawksbill turtle rookeries of the TCI. However, they are thought to be remnants of past populations that were subject to regular harvest (Richardson et al. 2009). Until recently, the legal turtle fishery of the TCI was likely to have been a threat to the local nesting turtle populations and impacted the recovery of both species here. The TCI’s hawksbill turtle fishery is thought to be one of the largest in the Atlantic (Humber et al. 2014; Stringell et al. 2013) and the take of breeding adults was a conservation concern (Stringell et al. 2013). There has been a clear need to better understand the dynamics of the nesting populations and examine the presence, behaviour and residency of adult marine turtles in the waters of the TCI, in order to inform management reform of the traditional turtle fishery of the TCI. In 2008, at the invitation of the local government, the TCI turtle project (TCITP) was established to assess both the biological and socio-economic aspects of the fishery and make management recommendations. We undertook a 2-year study to examine spatio- temporal patterns and magnitude of nesting in hawksbill and green turtles in the TCI and assess these patterns in relation to the fishery. We combine these observations of nesting activity, with information about the presence of adults in the TCI’s waters through captures by the fishery, from in-water surveys and satellite tracking. Satellite telemetry of adult marine turtles can be used to reveal valuable insights into migratory and residency be- haviours of adults, and provide context to conservation measures (Godley et al. 2008b; Hawkes et al. 2011, 2012; Hays et al. 2003; Rees et al. 2012; Scott et al. 2012). We also genetically characterise the marine turtle rookeries of the TCI using mitochondrial DNA markers. In this paper, we report on these multiple lines of biological evidence that un- derpinned the resultant recommendations for legislative change that were implemented by the Government of the TCI in July 2014 (Government of the Turks and Caicos Islands 2014); these changes promote ‘wise harvesting’ and are likely to have positive conser- vation impact both locally and internationally. Materials and methods Study site The TCI are located at the southeastern end of the Bahamas chain (21°45N, 71°35W). The majority of the human population lives on the three islands of Grand Turk, Providenciales and South Caicos. The economy of the TCI is driven principally by tourism, offshore 123 Biodivers Conserv finance and fishing. The spiny lobster (Panulirus argus) and queen conch (Strombus gigas) are the dominant fisheries, and largely supply the export market (Be´ne´ and Tewfik 2001; Tewfik and Be´ne´ 2004). As part of this mixed small scale fishery, marine turtles are usually captured opportunistically for personal consumption, although there is limited directed take for local commercial sale; export is prohibited (Richardson et al.