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Rincon-Diaz M.P.,University of Puerto Rico at San Juan | Van Dam R.P.,Chelonia Inc. | Sabat A.M.,University of Puerto Rico at San Juan
Journal of Herpetology | Year: 2011

Recent literature on foraging in Hawksbill Sea Turtles in the Caribbean region concludes that prey selectivity is a combination of preference for certain prey species and their local abundance. In this study, prey selectivity patterns were measured in five juvenile Hawksbill Sea Turtle (Eretmochelys imbricata) aggregations in the Culebra Archipelago, Puerto Rico, and the hypothesis that juvenile Hawksbill Sea Turtles exhibit selectivity for certain prey items independent of their environmental availability was tested. Hawksbill Sea Turtles showed positive selection for the corallimorph Ricordea florida, which was rare in all four study sites, and for the alga Lobophora variegata, that was abundant in one site. Turtles exhibited low preference for the sponge Chondrilla nucula, the most common prey item in both diet samples and the environment at all study sites. Low preference for this sponge corresponds to its high availability in the environment. Turtles also exhibited low preference for the sponge Cinacyrella sp. and the branching anemone Lebrunia danae. That juvenile hawksbills exhibited strong positive selectivity for rare items indicates that diet selection is not necessarily related to the abundance of the items in the environment. In addition, spatial variability in diet composition among Hawksbill Sea Turtles in the Culebra Archipelago indicates plasticity in their foraging habits. © 2011 Society for the Study of Amphibians and Reptiles.


Rincon-Diaz M.P.,University of Puerto Rico at San Juan | Van Dam R.P.,Chelonia Inc | Sabat A.M.,University of Puerto Rico at San Juan
Chelonian Conservation and Biology | Year: 2011

Habitat features influence the distribution and abundance of marine animals and are used to identify critical areas to protect threatened marine species. In this study, we surveyed juvenile hawksbill turtles in 5 localities of the Culebra Archipelago, Puerto Rico; described the habitats using cover of benthic features; and related relative abundance of turtles among localities with food availability. We tested the hypothesis that variability in turtle abundance among study sites was related to spatial variability in the availability of diet items. Our results point out that spatial variability in turtle abundance is not related to food availability by itself; rather, the structural complexity and types of benthic structure played a more important role in explaining the turtles' local abundance. The importance of structural complexity is most likely related to sheltering. © 2011 Chelonian Research Foundation.


Page-Karjian A.,University of Georgia | Rivera S.,Zoo Atlanta | Torres F.,U.S. Department of Agriculture | Van Dam R.,Chelonia Inc. | Brown C.,University of Georgia
Comparative Clinical Pathology | Year: 2015

In Puerto Rico, green sea turtles (Chelonia mydas) appear to congregate in certain areas that constitute neritic developmental habitats for juvenile green turtles and foraging habitats for migrating larger immature and adult green turtles. The objective of this study was to establish baseline blood health indices in free-ranging green sea turtles occupying such habitats in Puerto Rico. We analyzed packed cell volume, morphometrics, and plasma biochemistry and protein electrophoresis parameters for free-ranging green sea turtles in the Culebra archipelago of Puerto Rico. The general health of turtles included in this study was rated as good based on body condition, physical examination, and molecular diagnostics. We report packed cell volume, plasma biochemistry, and protein electrophoresis reference interval values for juvenile and subadult green sea turtles. Development of site-specific baseline blood health parameters for wild, healthy sea turtle populations is an important factor in creating effective management protocols and enhances our ability to understand the effects of anthropogenic and environmental changes on sea turtle health. © 2014, Springer-Verlag London.


Esteban N.,University of Swansea | van Dam R.P.,Chelonia Inc | Harrison E.,Sea Turtle Conservancy | Herrera A.,University of Exeter | Berkel J.,Statia National Marine Park
Marine Biology | Year: 2015

Satellite transmitters were deployed on three green turtles, Chelonia mydas, and two hawksbill turtles, Eretmochelys imbricata, nesting in the Lesser Antilles islands, Caribbean, between 2005 and 2007 to obtain preliminary information about the inter-nesting, migratory and foraging habitats in the region. Despite the extremely small dataset, both year-round residents and migrants were identified; specifically, (1) two green turtles used local shallow coastal sites within 50 km of the nesting beach during all of their inter-nesting periods and then settled at these sites on completion of their breeding seasons, (2) one hawksbill turtle travelled 200 km westward before reversing direction and settling within 50 km of the original nesting beach and (3) one green and one hawksbill turtle initially nested at the proximate site, before permanently relocating to an alternative nesting site over 190 km distant. A lack of nesting beach fidelity was supported by flipper tag datasets for the region. Tagging datasets from 2002 to 2012 supported that some green and hawksbill individuals exhibit low fidelity to nesting beaches, whereas other females exhibited a high degree of fidelity (26 turtles tagged, 40.0 km maximum distance recorded from original nesting beach). Individual turtles nesting on St Eustatius and St Maarten appear to exhibit behavioural plasticity in their inter-nesting behaviour and post-nesting migration routes in the eastern Caribbean. The tracking and tagging data combined indicate that some of the green and hawksbill females that nest in the Lesser Antilles islands are year-round residents, whilst others may nest and forage at alternative sites. Thus, continued year-round protection of these islands and implementation of protection programmes in nearby islands could contribute towards safeguarding the green and hawksbill populations of the region. © 2015, Springer-Verlag Berlin Heidelberg.


Nuuttila H.K.,Bangor University | Nuuttila H.K.,University of Swansea | Thomas L.,University of St. Andrews | Hiddink J.G.,Bangor University | And 6 more authors.
Journal of the Acoustical Society of America | Year: 2013

Acoustic dataloggers are used for monitoring the occurrence of cetaceans and can aid in fulfilling statutory monitoring requirements of protected species. Although useful for long-term monitoring, their spatial coverage is restricted, and for many devices the effective detection distance is not specified. A generalized additive mixed model (GAMM) was used to investigate the effects of (1) distance from datalogger, (2) animal behavior (feeding and traveling), and (3) group size on the detection probability of bottlenose dolphins (Tursiops truncatus) with autonomous dataloggers (C-PODs) validated with visual observations. The average probability of acoustic detection for minutes with a sighting was 0.59 and the maximum detection distance ranged from 1343-1779 m. Minutes with feeding activity had higher acoustic detection rates and longer average effective detection radius (EDR) than traveling ones. The detection probability for single dolphins was significantly higher than for groups, indicating that their acoustic behavior may differ from those of larger groups in the area, making them more detectable. The C-POD is effective at detecting dolphin presence but the effects of behavior and group size on detectability create challenges for estimating density from detections as higher detection rate of feeding dolphins could yield erroneously high density estimates in feeding areas. © 2013 Acoustical Society of America.


PubMed | Chelonia Ltd, Andrews University, National Oceanic and Atmospheric Administration, CICESE and Southwest Fisheries Science Center
Type: Journal Article | Journal: Conservation biology : the journal of the Society for Conservation Biology | Year: 2016

The vaquita (Phocoena sinus) is the worlds most endangered marine mammal with approximately 245 individuals remaining in 2008. This species of porpoise is endemic to the northern Gulf of California, Mexico, and historically the population has declined because of unsustainable bycatch in gillnets. An illegal gillnet fishery for an endangered fish, the totoaba (Totoaba macdonaldi), has recently resurged throughout the vaquitas range. The secretive but lucrative wildlife trade with China for totoaba swim bladders has probably increased vaquita bycatch mortality by an unknown amount. Precise population monitoring by visual surveys is difficult because vaquitas are inherently hard to see and have now become so rare that sighting rates are very low. However, their echolocation clicks can be identified readily on specialized acoustic detectors. Acoustic detections on an array of 46 moored detectors indicated vaquita acoustic activity declined by 80% between 2011 and 2015 in the central part of the species range. Statistical models estimated an annual rate of decline of 34% (95% Bayesian credible interval -48% to -21%). Based on results from 2011 to 2014, the government of Mexico enacted and is enforcing an emergency 2-year ban on gillnets throughout the species range to prevent extinction, at a cost of US$74 million to compensate fishers. Developing precise acoustic monitoring methods proved critical to exposing the severity of vaquitas decline and emphasizes the need for continual monitoring to effectively manage critically endangered species.


Temple A.J.,Northumbria University | Tregenza N.,Chelonia Ltd | Amir O.A.,Ministry of Livestock and Fisheries | Jiddawi N.,University of Dar es Salaam | Berggren P.,Northumbria University
PLoS ONE | Year: 2016

Understanding temporal patterns in distribution, occurrence and behaviour is vital for the effective conservation of cetaceans. This study used cetacean click detectors (C-PODs) to investigate spatial and temporal variation in occurrence and foraging activity of the Indo- Pacific bottlenose (Tursiops aduncus) and Indian Ocean humpback (Sousa plumbea) dolphins resident in the Menai Bay Conservation Area (MBCA), Zanzibar, Tanzania. Occurrence was measured using detection positive minutes. Inter-click intervals were used to identify terminal buzz vocalisations, allowing for analysis of foraging activity. Data were analysed in relation to spatial (location) and temporal (monsoon season, diel phase and tidal phase) variables. Results showed significantly increased occurrence and foraging activity of dolphins in southern areas and during hours of darkness. Higher occurrence at night was not explained by diel variation in echolocation rate and so were considered representative of occurrence patterns. Both tidal phase and monsoon season influenced occurrence but results varied among sites, with no general patterns found. Foraging activity was greatest during hours of darkness, High water and Flood tidal phases. Comparisons of echolocation data among sites suggested differences in the broadband click spectra of MBCA dolphins, possibly indicative of species differences. These dolphin populations are threatened by unsustainable fisheries bycatch and tourism activities. The spatial and temporal patterns identified in this study have implications for future conservation and management actions with regards to these two threats. Further, the results indicate future potential for using passive acoustics to identify and monitor the occurrence of these two species in areas where they co-exist. © 2016 Temple et al.This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.


Cuevas E.,CINVESTAV | Abreu-Grobois F.A.,National Autonomous University of Mexico | Guzman-Hernandez V.,Area de Proteccion de Flora y Fauna Laguna de Terminos | Liceaga-Correa M.A.,CINVESTAV | van Dam R.P.,Chelonia Inc.
Endangered Species Research | Year: 2010

The Yucatan Peninsula harbors the largest nesting population of hawksbill turtle Eretmochelys imbricata in the Atlantic Basin. In Mexico, one of the most significant conservation problems for this species is the lack of knowledge on migratory patterns and the location of feeding grounds for post-nesting hawksbill females. The main goal of this study was to gather information on the hawksbill's migratory patterns and the location of their feeding grounds by tracking 3 post-nesting females from Campeche state, Mexico. We attached satellite transmitters and tracked the 3 turtles for 166, 446 and 510 d, respectively. The turtles remained within Mexican territorial waters, reaching separate foraging grounds off the coast of Campeche and in the Mexican Caribbean. No significant relationships were observed between turtles' migrating behavior and sea-surface temperature or geostrophic currents. Spatial analysis of the data recorded in this study has generated novel information on hawksbill turtle migratory patterns and feeding grounds, which will aid in decisionmaking for hawksbill turtle conservation in the Yucatan Peninsula. © Inter-Research 2008.


Patricio A.R.,University of Puerto Rico at San Juan | Velez-Zuazo X.,University of Puerto Rico at San Juan | Diez C.E.,Programa de Especies Protegidas | Van Dam R.,Chelonia Inc. | Sabat A.M.,University of Puerto Rico at San Juan
Marine Ecology Progress Series | Year: 2011

Inshore bays are key foraging grounds for immature green turtles Chelonia mydas. At these confined areas, capture-mark-recapture (CMR) programs generate valuable information that can be used to estimate vital rates, essential for the effective conservation of this endangered species. We compiled the CMR history profiles of 273 individuals from 13 yr of in-water surveys and employed the Cormack-Jolly-Seber model to estimate the survival probabilities of green turtles in 2 neritic bays at Culebra municipality, Puerto Rico. The CMR profiles were grouped into 2 size classes: juvenile and subadult. No adults were captured during the study. We found no significant differences in survival probability between the green turtles occupying each bay. We also assessed the survival probability of fibropapillomatosis (FP)-afflicted turtles versus FP-free turtles and found no significant differences among these groups. However, there was a significant difference in survival between the 2 size classes. Juveniles showed a higher survival probability (0.8322, 95% CI = 0.7875 to 0.8690) than subadults (0.5290, 95% CI = 0.3851 to 0.6682). The low survival of subadults is potentially biased by the permanent emigration of some of these individuals. Previous studies have shown that larger immatures leave shallow protected bays and occupy deeper open waters, sometimes associated with adults. Juveniles seem to be resident, and their survival rate can serve as a reference value for viability analysis. This is the first study on the survival of green turtles in the West Indies. © 2011 Inter-Research.


Tom H.,Cornwall Wildlife Trust | Tom H.,Chelonia Ltd | Ruth W.,Cornwall Wildlife Trust | Ruth W.,Chelonia Ltd | And 4 more authors.
Journal of Cetacean Research and Management | Year: 2012

In Europe, problems with the use of pingers on larger fishing vessels have raised the question as to whether pingers would be practical on smaller vessels, which are a large proportion of the European static net fishing fleet. In this study, four netting vessels less than 10m long used AQUAmark pingers on part of their nets off the southwest coast of Britain over a 12 month period. Boat skippers recorded ease of use. Acoustic click detectors were deployed on test and control nets to assess the response of cetaceans to the pingers. No significant practical problems, apart from premature failure of pingers, were encountered. During the study, only one harbour porpoise was bycaught, in an unpingered net. In 650 days of acoustic data from pingered and non-pingered nets, matched by location, date and boat, there was a highly significant reduction in the number of porpoise clicks recorded at nets with pingers to 48% of the number predicted from the number recorded at control nets (range 35-51%). To assess habituation, single, modified pingers that were active for alternate seven hour periods were moored below a click detector at two sites, one of which has strong tides and high levels of associated ambient noise. This study showed a stronger pinger effect at the quiet site and a much reduced effect at the noisy site. There was evidence of a period of exclusion of porpoises following pinger use that could exceed seven hours, and no evidence of habituation. Results suggest that pingers are practical on small vessels, that they reduce harbour porpoise activity around nets and are therefore likely to reduce bycatch. Easier means of detecting pinger failure are needed. Pingers should be considered as a bycatch mitigation method in small vessel fisheries using bottom set nets.

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