Sea Turtle Nesting Activity in Ghana, West Africa

Andrews Agyekumhene; Prince Yankson; Leyna Stemle; Phil Allman

doi:10.2744/ccb-1487.1

Finding of a two-headed green turtle embryo during nest monitoring in Baa Atoll, Maldives

Onderstepoort Journal of Veterinary Research ◽

10.4102/ojvr.v88i1.1940 ◽

2021 ◽

Vol 88 (1) ◽

Author(s):

Stephanie Köhnk ◽

Rosie Brown ◽

Amelia Liddell

Keyword(s):

Success Rate ◽

Green Turtle ◽

Hatching Success ◽

Sea Turtles ◽

Sea Turtle ◽

Radiographic Images ◽

Marine Turtles ◽

Green Sea Turtles ◽

Neck Area ◽

Nesting Activity

Green sea turtles are one of the two species of marine turtles known to nest in the Maldives. The prevalent time of nesting seems to be inconsistent throughout the island nation. In this study, sea turtle nesting activity was monitored on the island of Coco Palm Dhuni Kolhu in Baa Atoll over a period of 12 months. A total of 13 nests were confirmed with a median hatching success rate of 89.58% as ascertained by nest excavation. In one of the nests, a severely deformed hatchling with polycephaly, an opening in the neck area and a lordotic spine was found, and we investigated in detail with radiographic images and a necropsy. Our findings support the importance of consistent nesting activity and nest monitoring efforts in the country as a basis for conservation efforts.

Download Full-text

Nesting biology and conservation of the olive ridley sea turtle (Lepidochelys olivacea) in Brazil, 1991/1992 to 2002/2003

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315407056378 ◽

2007 ◽

Vol 87 (4) ◽

pp. 1047-1056 ◽

Cited By ~ 41

Author(s):

Augusto Cesar C.D. da Silva ◽

Jaqueline C. de Castilhos ◽

Gustave G. Lopez ◽

Paulo C.R. Barata

Keyword(s):

Fold Increase ◽

Sea Turtle ◽

Biological Data ◽

Biological Knowledge ◽

Olive Ridley ◽

Nesting Biology ◽

Western Atlantic ◽

Lepidochelys Olivacea ◽

Turtle Conservation ◽

Nesting Activity

This article presents biological data and an assessment of the conservation of the olive ridley sea turtle (Lepidochelys olivacea) population nesting in the States of Sergipe and Bahia, north-eastern Brazil, between 1991/1992 and 2002/2003. Projeto TAMAR-IBAMA (the Brazilian Sea Turtle Conservation Programme) maintains seven field stations in that region to monitor nesting activity over 339 km of beach. An increasing trend was observed in the estimated number of nests per nesting season: from 252 nests in 1991/1992 to 2606 in 2002/2003, an approximately 10-fold increase in 11 years. The available data and biological knowledge suggest that TAMAR's conservation efforts may have contributed to the significant increase in olive ridley nesting in Sergipe and Bahia; that increase is not only of regional importance, but also of significance at the western Atlantic level.

Download Full-text

Nesting activity of the Loggerhead sea turtle, Caretta caretta, in Calabria: 2016-2020 reproductive seasons

Mediterranean Marine Science ◽

10.12681/mms.26085 ◽

2021 ◽

Author(s):

MARIA DENARO ◽

TERESA MALITO ◽

CARMELA MANCUSO ◽

GIOVANNI PARISE ◽

SALVATORE URSO

Keyword(s):

New Technologies ◽

Survey Methods ◽

Loggerhead Turtle ◽

Sea Turtle ◽

Success Rates ◽

Monitoring Method ◽

Loggerhead Sea Turtle ◽

Emergence Success ◽

The Mean ◽

Nesting Activity

The nesting activity of the loggerhead turtle along the coast of Calabria during five reproductive seasons (2016-2020) is presented. From May to August, survey methods were conducted using traditional observations on foot and utilizing additional innovative technologies, including electric fat bikes and drones. Monitoring was intensively focused on a key nesting area of approximately 40 km located on the southernmost Ionian coast of Reggio Calabria, and, for only the 2020 season, the area was extended an additional 40 km northeast. In the five nesting seasons, 419 female emergences were recorded, 192 of which were classified as nests. Overall, 65.1% (n = 125) of nests were found along the area regularly monitored in all nesting seasons. The maximum nesting activity was observed during July, and the mean nesting success was 45.8%. The average number of eggs for all seasons was 92.2 (n = 163; S.D.: ± 21.1; range: 39-160). The mean hatching and emergence success rates were 70.8% and 62.5%, respectively. The mean incubation period was 49 days (n = 122; S.D.: ± 5.4; range: 42-82). Considering previous data from the same area, our study shows an actual increase in nesting activity, probably due to the implementation of an effective monitoring method that includes the use of new technologies, which made it possible to expand the regularly monitored area, and a greater awareness campaign in recent years. Regarding the reproductive parameters, our data is similar to that reported for other Mediterranean nesting grounds.

Download Full-text

Green turtle (Chelonia mydas) nesting on Atol das Rocas, north-eastern Brazil, 1990–2008

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s002531541200046x ◽

2012 ◽

Vol 93 (4) ◽

pp. 1117-1132 ◽

Cited By ~ 19

Author(s):

Claudio Bellini ◽

Armando J.B. Santos ◽

Alice Grossman ◽

Maria A. Marcovaldi ◽

Paulo C. R. Barata

Keyword(s):

Green Turtle ◽

Carapace Length ◽

Temporal Distribution ◽

Chelonia Mydas ◽

Sea Turtle ◽

Annual Number ◽

Eastern Brazil ◽

North Eastern ◽

The Mean ◽

Nesting Activity

In this paper, information is presented on green turtle (Chelonia mydas) nesting on Atol das Rocas (Rocas Atoll), north-eastern Brazil. The temporal distribution of nesting events per season, annual number of nests, carapace length of nesting females, clutch size, hatching success, incubation period, internesting interval, clutch frequency, observed reproductive lifespan, and remigration period are reported. The study period included the nesting seasons from 1990 to 2008, but no regular beach monitoring was carried out in 1998 and 1999. Two sorts of methods were applied to the estimation of the annual number of nests in some seasons. Taking into account the estimated annual numbers of nests, the mean annual number of nests in the study period, excluding 1998–1999, was 335 (standard deviation = 139, range = 136–563, N = 17). An analysis of the available data indicates that the average nesting levels at the beginning of the study period (the first five seasons) and at its end (the last five seasons) were roughly the same. The mean curved carapace length of the nesting turtles decreased significantly during the study period, from 115.9 cm in 1990–1992 to 112.9 cm in 2006–2008. Atol das Rocas was established as a federal biological reserve in 1979, but regular sea turtle conservation activities actually started there in 1990. Since that year, the killing of nesting turtles has ceased, nesting activity by the turtles can proceed in an undisturbed fashion, and their clutches can incubate in a protected environment.

Download Full-text

Nesting and at-sea distribution of marine turtles in Angola, West Africa, 2000–2006: occurrence, threats and conservation implications

Oryx ◽

10.1017/s003060530700186x ◽

2007 ◽

Vol 41 (2) ◽

pp. 224-231 ◽

Cited By ~ 14

Author(s):

Caroline R. Weir ◽

Tamar Ron ◽

Miguel Morais ◽

Agostinho Domingos C. Duarte

Keyword(s):

West Africa ◽

Chelonia Mydas ◽

Sea Turtle ◽

Dermochelys Coriacea ◽

Fishing Communities ◽

Nest Density ◽

Olive Ridley ◽

Marine Turtles ◽

Conservation Implications ◽

Olive Ridley Turtle

AbstractThe status of marine turtles in Angola, West Africa, is poorly known, and therefore during 2000–2006 a combination of both dedicated and opportunistic beach and at-sea turtle surveys were carried out, and interviews conducted with fishing communities and at markets. Green Chelonia mydas, olive ridley Lepidochelys olivacea, leatherback Dermochelys coriacea and loggerhead turtles Caretta caretta were recorded, and nesting of the first three species confirmed during September–March (peaking November–December). Green turtles nested mainly in the south, leatherback turtles in north and central Angola, and olive ridley turtle nesting was widespread. Olive ridley turtle nest density at Palmeirinhas averaged 32 nests km−1. At-sea surveys produced 298 turtle records, with peak occurrence during August. Significant anthropogenic-related mortality (including exploitation of meat and eggs and fishing bycatch) was recorded, in addition to natural predation and other threats. Maintenance of the long-term sustainability of these turtle populations should focus on the involvement of fishing communities and increasing awareness throughout Angola.

Download Full-text