Fishing methods to reduce sea turtle mortality associated with pelagic longlines

2005 ◽  
Vol 62 (5) ◽  
pp. 965-981 ◽  
Author(s):  
John W Watson ◽  
Sheryan P Epperly ◽  
Arvind K Shah ◽  
Daniel G Foster
Keyword(s):  
North Atlantic ◽  
North Atlantic Ocean ◽  
Sea Turtles ◽  
Capture Rate ◽  
Sea Turtle ◽  
Mitigation Measures ◽  
Dermochelys Coriacea ◽  
Primary Target ◽  
Negative Effect ◽  
Catch Rates

Changes in hook design and bait type were investigated as measures to reduce the bycatch of sea turtles on pelagic longlines in the western North Atlantic Ocean. Specifically, the effectiveness of 18/0 circle hooks and mackerel (Scomber scombrus) bait was evaluated with respect to reducing sea turtle interactions and maintaining swordfish (Xiphias gladius) and tuna (Thunnus spp.) catch rates. Individually, circle hooks and mackerel bait significantly reduced both loggerhead (Caretta caretta) and leatherback (Dermochelys coriacea) sea turtle bycatch. Circle hooks also significantly reduced the rate of hook ingestion by the loggerheads, potentially reducing postrelease mortality. The combination of circle hooks and mackerel bait was even more effective for loggerhead turtles and had no negative effect on swordfish catch. These modifications in fishing methods, in conjunction with tools developed to remove hooks and line from the turtles, significantly reduced the capture rate of sea turtles and potentially the post-hooking mortality of those that were caught and did not negatively impact the primary target species catch rate. In addition, these mitigation measures have the potential to reduce mortality of sea turtles and other bycatch species worldwide.

Tursiocola neliana sp. nov (Bacillariophyceae) epizoic on South African leatherback sea turtles (Dermochelys coriacea) and new observations on the genus Tursiocola

Phytotaxa ◽  
2020 ◽  
Vol 453 (1) ◽  
pp. 1-15 ◽  
Author(s):  
ROKSANA MAJEWSKA
Keyword(s):  
Sea Turtles ◽  
Central Area ◽  
Sea Turtle ◽  
Dermochelys Coriacea ◽  
Eastern Coast ◽  
New Taxon ◽  
Freshwater Turtles ◽  
Diatom Genus ◽  
Leatherback Sea Turtles ◽  
Internal Side

Tursiocola, a presumably exclusively epizoic diatom genus, comprises species found on various aquatic animals such as cetaceans, manatees, and marine and freshwater turtles. The genus is characterised by linear or lanceolate valves with well-developed pseudosepta at both poles, a valvocopula with three pairs of siliceous tabs, and a butterfly-like structure extending from the central nodule on the internal side of the valve. The current study describes a novel species of Tursiocola, T. neliana Majewska sp. nov. that grows epizoically on leatherback sea turtles from the Eastern Coast of South Africa based on detailed observations using light and scanning electron microscopy. The new taxon resembles the other currently known sea turtle-associated Tursiocola species in possessing relatively small, slightly heteropolar valves with acute apices and a strongly reduced butterfly structure on the internal side. However, T. neliana differs from all other members of the genus in being distinctly dorsiventral, with a clearly bowtie-shaped central area, unequal stria density on two sides of the raphe-sternum, and up to 8 areolae per stria. The description of the new taxon brings the total number of the sea turtle-associated Tursiocola species known so far up to four. An emended description of Tursiocola is proposed based on the new observations presented in this and other recent reports. Furthermore, the current understanding of the genus ecology is summarised.

Estimating past and present sex ratios of sea turtles in Suriname

1996 ◽  
Vol 74 (2) ◽  
pp. 267-277 ◽  
Author(s):  
Matthew H. Godfrey ◽  
N. Mrosovsky ◽  
R. Barreto
Keyword(s):  
Sea Turtles ◽  
Sex Ratios ◽  
Negative Relationship ◽  
Chelonia Mydas ◽  
Sea Turtle ◽  
Dermochelys Coriacea ◽  
Green Turtles ◽  
Sand Temperature ◽  
Turtle Conservation ◽  
Sea Turtle Conservation

Leatherback (Dermochelys coriacea) and green (Chelonia mydas) sea turtles in Suriname lay eggs over several months of the year. During this nesting season, changes in rainfall produce changes in sand temperature, which in turn influence the sexual differentiation of incubating sea turtle embryos. The overall sex ratio of leatherback and green sea turtle hatchlings produced at Matapica beach in Suriname was investigated. Estimates of the sex ratios of these turtles in 1993 (green turtles 63.8% female, leatherbacks 69.4% female) were roughly 10% more female-biased than those from an earlier study in 1982. For both species, a significant negative relationship was found between monthly rainfall and monthly sex ratios. Using this relationship and data on rainfall in the past, it was possible to estimate overall sex ratios for an additional 12 years. These estimates varied considerably among different years, ranging from 20 to 90% female in the case of green turtles. Nevertheless, males tended to be produced primarily in April and May, while some females were produced in all months. Such seasonal patterns of production of turtles of different sexes have implications for sea turtle conservation programs that involve manipulating or harvesting eggs.

scholarly journals End of the century CO2 concentrations do not have a negative effect on vital rates of Calanus finmarchicus, an ecologically critical planktonic species in North Atlantic ecosystems

2016 ◽  
Vol 73 (3) ◽  
pp. 937-950 ◽  
Author(s):  
Jeffrey A. Runge ◽  
David M. Fields ◽  
Cameron R. S. Thompson ◽  
Steven D. Shema ◽  
Reidun M. Bjelland ◽  
...  
Keyword(s):  
North Atlantic ◽  
North Atlantic Ocean ◽  
Co2 Concentration ◽  
Calanus Finmarchicus ◽  
Vital Rates ◽  
Significant Treatment ◽  
The North ◽  
Pco2 Treatment ◽  
Negative Effect ◽  
Abundance And Distribution

Abstract The Subarctic copepod, Calanus finmarchicus, is an ecologically critical foundation species throughout the North Atlantic Ocean. Any change in the abundance and distribution of C. finmarchicus would have profound effects on North Atlantic pelagic ecosystems and the services that they support, particularly on the coastal shelves located at the southern margins of the species' range. We tested the hypothesis that the physiological rates and processes of C. finmarchicus, determining its vital rates, are unaffected by increases in CO2 concentration predicted to occur in the surface waters of the ocean during the next 100 years. We reared C. finmarchicus from eggs to adults at a control (580 µatm, the ambient concentration at the laboratory's seawater intake) and at predicted mid-range (1200 µatm) and high (1900 µatm) pCO2. There was no significant effect of pCO2 on development times, lipid accumulation, feeding rate, or metabolic rate. Small but significant treatment effects were found in body length and mass (in terms of dry, carbon and nitrogen mass), notably a somewhat larger body size at the mid-pCO2 treatment; that is, a putatively beneficial effect. Based on these results, and a review of other studies of Calanus, we conclude that the present parameterizations of vital rates in models of C. finmarchicus population dynamics, used to generate scenarios of abundance and distribution of this species under future conditions, do not require an “ocean acidification effect” adjustment. A review of research on planktonic copepods indicates that, with only a few exceptions, impacts of increased CO2 are small at the levels predicted to occur during the next century.

scholarly journals Chelonid Alphaherpesvirus 5 Prevalence and First Confirmed Case of Sea Turtle Fibropapillomatosis in Grenada, West Indies

Animals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1490
Author(s):  
Amanda James ◽  
Annie Page-Karjian ◽  
Kate E. Charles ◽  
Jonnel Edwards ◽  
Christopher R. Gregory ◽  
...  
Keyword(s):  
West Indies ◽  
Sea Turtles ◽  
Chelonia Mydas ◽  
Sea Turtle ◽  
Dermochelys Coriacea ◽  
Neoplastic Disease ◽  
Extrinsic Factors ◽  
Eretmochelys Imbricata ◽  
Specific Pcr ◽  
The Impact

Chelonid alphaherpesvirus 5 (ChHV5) is strongly associated with fibropapillomatosis, a neoplastic disease of sea turtles that can result in debilitation and mortality. The objectives of this study were to examine green (Chelonia mydas), hawksbill (Eretmochelys imbricata), and leatherback (Dermochelys coriacea) sea turtles in Grenada, West Indies, for fibropapillomatosis and to utilize ChHV5-specific PCR, degenerate herpesvirus PCR, and serology to non-invasively evaluate the prevalence of ChHV5 infection and exposure. One-hundred and sixty-seven turtles examined from 2017 to 2019 demonstrated no external fibropapilloma-like lesions and no amplification of ChHV5 DNA from whole blood or skin biopsies. An ELISA performed on serum detected ChHV5-specific IgY in 18/52 (34.6%) of green turtles tested. In 2020, an adult, female green turtle presented for necropsy from the inshore waters of Grenada with severe emaciation and cutaneous fibropapillomas. Multiple tumors tested positive for ChHV5 by qPCR, providing the first confirmed case of ChHV5-associated fibropapillomatosis in Grenada. These results indicate that active ChHV5 infection is rare, although viral exposure in green sea turtles is relatively high. The impact of fibropapillomatosis in Grenada is suggested to be low at the present time and further studies comparing host genetics and immunologic factors, as well as examination into extrinsic factors that may influence disease, are warranted.

scholarly journals Strandings of sea turtles on beaches around the oil capital in Brazil

2021 ◽  
Vol 16 (4) ◽  
pp. 521-538
Author(s):  
Raísa da Silva Costa Rêgo ◽  
Eric Azevedo Cazetta ◽  
Caio Henrique Gonçalves Cutrim ◽  
Amanda Soares Miranda ◽  
Ana Paula Albano Araújo ◽  
...  
Keyword(s):  
Sea Turtles ◽  
Chelonia Mydas ◽  
Sea Turtle ◽  
The State ◽  
Dermochelys Coriacea ◽  
Anthropogenic Factors ◽  
Long Beach ◽  
Eretmochelys Imbricata ◽  
Lepidochelys Olivacea ◽  
The North

The south-western region of the Atlantic Ocean has feeding and nesting areas for the five species of sea turtles registered in Brazil, which are in different degrees of extinction threat, mainly due to anthropogenic factors. Fishing and the ingestion of solid waste, were identified as causing stranding and the mortality of sea turtles. In this work, data from the monitoring of beaches in the Municipalities of Macaé and Rio das Ostras, important oil zone in Brazil, in the north-central region of the State of Rio de Janeiro, were used in order to analyse the effects of seasonality on the sea turtle stranding. The monitoring was carried out daily from September 2017 to June 2019, in a study area covering 23.8 km long beach. Stranding data were obtained from active (n = 126) and passive (n = 66) monitoring of beaches and included the records of Chelonia mydas (n = 151), Caretta caretta (n = 23), Lepidochelys olivacea (n = 14), Dermochelys coriacea (n = 2) and Eretmochelys imbricata (n = 1). The largest stranding record occurred in the summer (n = 61) and spring (n = 60), a period compatible with the reproductive season of the species. The results obtained in this study emphasise the importance of the analysis of strandings of sea turtles, which provide relevant data on the biology of the group, the intra and interspecific dynamics and the state of conservation of these animals.

scholarly journals Methods to Reduce Sea Turtle Interactions in the Atlantic Canadian Pelagic Long Line Fleet

2017 ◽  
Author(s):  
Zachary T. Sherker
Keyword(s):  
Sea Turtles ◽  
The United States ◽  
Sea Turtle ◽  
Fishing Effort ◽  
Dermochelys Coriacea ◽  
Small Scale ◽  
The North ◽  
Spatio Temporal ◽  
Socio Economic Impact ◽  
By Catch

AbstractThis project investigates the role of fisheries management in the conservation of loggerhead (Caretta caretta) and leatherback sea turtles (Dermochelys coriacea), both of which are currently listed as vulnerable by the IUCN (International Union for Conservation of Nature). These species migrate from nesting grounds in South America to feed on gelatinous zooplankton (jellyfish) in the North Atlantic off the coast of the United States and Canada. The seasonal foraging grounds of sea turtles heavily overlap with areas of high fishing effort for the longline tuna and swordfish fleet, a fishery that has significantly high rates of sea turtle incidents. The dynamic nature of sea turtle foraging patterns renders static spatio-temporal fishing area closures ineffective. Rather, turtle by-catch mitigation requires small-scale, event-triggered closures and decentralized management to reduce incidents while minimizing the negative socio-economic impact of area closures on fishermen. A number of methods that increase fishing selectivity have been implemented in other commercial fisheries around the globe and are suggested for the Atlantic Canadian fleet moving forward.

scholarly journals Orientation behaviour of leatherback sea turtles within the North Atlantic subtropical gyre

2015 ◽  
Vol 282 (1804) ◽  
pp. 20143129 ◽  
Author(s):  
Kara L. Dodge ◽  
Benjamin Galuardi ◽  
Molly E. Lutcavage
Keyword(s):  
North Atlantic ◽  
Sea Turtles ◽  
Sensory Information ◽  
Subtropical Gyre ◽  
Dermochelys Coriacea ◽  
Male Adult ◽  
The North ◽  
The North Atlantic ◽  
Leatherback Sea Turtles ◽  
Nesting Beaches

Leatherback sea turtles ( Dermochelys coriacea ) travel thousands of kilometres between temperate feeding and tropical breeding/over-wintering grounds, with adult turtles able to pinpoint specific nesting beaches after multi-year absences. Their extensive migrations often occur in oceanic habitat where limited known sensory information is available to aid in orientation. Here, we examined the migratory orientation of adult male, adult female and subadult leatherbacks during their open-ocean movements within the North Atlantic subtropical gyre by analysing satellite-derived tracks from fifteen individuals over a 2-year period. To determine the turtles' true headings, we corrected the reconstructed tracks for current drift and found negligible differences between current-corrected and observed tracks within the gyre. Individual leatherback headings were remarkably consistent throughout the subtropical gyre, with turtles significantly oriented to the south-southeast. Adult leatherbacks of both sexes maintained similar mean headings and showed greater orientation precision overall. The consistent headings maintained by adult and subadult leatherbacks within the gyre suggest use of a common compass sense.

scholarly journals First satellite tracks of neonate sea turtles redefine the ‘lost years’ oceanic niche

2014 ◽  
Vol 281 (1781) ◽  
pp. 20133039 ◽  
Author(s):  
Katherine L. Mansfield ◽  
Jeanette Wyneken ◽  
Warren P. Porter ◽  
Jiangang Luo
Keyword(s):  
North Atlantic ◽  
Sea Turtles ◽  
Life Stage ◽  
Sea Turtle ◽  
Sea Surface ◽  
The North ◽  
Satellite Transmitters ◽  
The North Atlantic ◽  
Solar Powered

Few at-sea behavioural data exist for oceanic-stage neonate sea turtles, a life-stage commonly referred to as the sea turtle ‘lost years’. Historically, the long-term tracking of small, fast-growing organisms in the open ocean was logistically or technologically impossible. Here, we provide the first long-term satellite tracks of neonate sea turtles. Loggerheads ( Caretta caretta ) were remotely tracked in the Atlantic Ocean using small solar-powered satellite transmitters. We show that oceanic-stage turtles (i) rarely travel in Continental Shelf waters, (ii) frequently depart the currents associated with the North Atlantic Subtropical Gyre, (iii) travel quickly when in Gyre currents, and (iv) select sea surface habitats that are likely to provide a thermal benefit or refuge to young sea turtles, supporting growth, foraging and survival. Our satellite tracks help define Atlantic loggerhead nursery grounds and early loggerhead habitat use, allowing us to re-examine sea turtle ‘lost years’ paradigms.

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