Variation of Size at Maturity of Female Hawksbill Turtles (&lt;i&gt;Eretmochelys imbricata&lt;/i&gt;), with Speculations on Life-History Tactics Relative to Proper Stock Management

Witzell, W. N.

doi:10.5358/hsj1972.11.2_46

Cited by 3 publications

(4 citation statements)

References 8 publications

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“…In the current study, the percentage of yolkless eggs, including very small eggs and odd-shaped eggs, ranged between 6 and 21% (Table 2), which was within the limits of previous study (Hirth, 1980). However, the clutch size of wild hawksbills ranged from 32-250 eggs, while the diameter of normal eggs ranged from 34-39.6 mm (Witzell and Banner, 1980;Limpus et al, 1983;Hirth et al, 1985;Witzell, 1985;Wood, 1986;Miller, 1997;Moncada et al, 1999;Pilcher and Ali, 1999;Xavier et al, 2006). In the current study, the clutch sizes produced by the hawksbills were relatively small; however, for eight of nine turtles, the clutch sizes (except Turtle no.…”

Section: Discussionsupporting

confidence: 54%

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Induction of Oviposition by the Administration of Oxytocin in Hawksbill Turtles

et al. 2014

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We set out to develop an oviposition induction technique for captive female hawksbill turtles Eretmochelys imbricata. The infertile eggs of nine females were induced to develop by the administration of follicle-stimulating hormone, after which we investigated the effects of administering oxytocin on oviposition. Seven of the turtles were held in a stationary horizontal position on a retention stand, and then oxytocin was administrated (0.6-0.8 units/kg of body weight; 5 mL). The seven turtles were retained for a mandatory 2 h period after oxytocin administration, and were then returned to the holding tanks. As the control, normal saline (5 mL) was administered to the other two turtles, followed by the administration of oxytocin after 24 h. The eggs in oviducts of all nine turtles were observed by ultrasonography at 24 h after oxytocin administration. The control experiment validated that stationary retention and normal saline administration had no effect on egg oviposition. Eight of the turtles began ovipositing eggs at 17-43 min after oxytocin administration, while one began ovipositing in the holding tank immediately after retention. All turtles finished ovipositing eggs within 24 h of oxytocin administration. This report is the first to demonstrate successful induced oviposition in sea turtles. We suggest that the muscles in the oviducts of hawksbill turtles may respond to relatively lower doses of oxytocin (inducing contractions) compared to land and freshwater turtles (4-40 units/kg) based on existing studies.

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Section: Discussionsupporting

confidence: 54%

“…3) were within the limits of previous studies (Table 2). Witzell (1985) reported that turtle body size and age correlate with clutch size in nesting hawksbill turtles. In our study, seven of the nine hawksbills were definitely virgins, because these turtles were bred in captivity (hatching in 1994).…”

Section: Discussionmentioning

confidence: 97%

Induction of Oviposition by the Administration of Oxytocin in Hawksbill Turtles

et al. 2014

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“…Comparisons of the morphologies among populations provide a better understanding of evolutionary and genetic relationships, whereas comparisons of the body sizes among individuals and populations help to clarify physiological and ecological relationships. It has been reported that body size is connected to body temperature (Spotila and Standora 1985), metabolic rate (Prange and Jackson 1976), growth rate (Bjorndal and Bolten 1988), and clutch size (Witzell 1985). Because it is relatively easy to measure the morphological characteristics of marine turtles, there have been a number of studies of carapace size in various populations of the hawksbill turtle, Eretmochelys imbricata (Linnaeus, 1766) (Witzell 1985).…”

Section: Introductionmentioning

confidence: 99%

“…It has been reported that body size is connected to body temperature (Spotila and Standora 1985), metabolic rate (Prange and Jackson 1976), growth rate (Bjorndal and Bolten 1988), and clutch size (Witzell 1985). Because it is relatively easy to measure the morphological characteristics of marine turtles, there have been a number of studies of carapace size in various populations of the hawksbill turtle, Eretmochelys imbricata (Linnaeus, 1766) (Witzell 1985). However, because of the difficulty of gathering specimens and determining the sex of immature turtles, these studies often had only a small sample size and hadn't dealt with the distinction between females and males.…”

Section: Introductionmentioning

confidence: 99%

Morphological Characteristics of the Carapace of the Hawksbill Turtle, Eretmochelys imbricata, from Cuban Waters

Kobayashi

2004

GCR

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Hawksbill turtles, Eretmochelys imbricata (Linnaeus, 1766), from Cuban waters of the Caribbean were analyzed to determine the relationships between straight carapace length (SCL) and either straight carapace width (SCW) or body weight (Wt). The regression equations were SCW = 0.9136(SCL) 0.951 (R 2 = 0.923, n = 315) and Wt = 4.17 10 -4 (SCL) 2.68 (R 2 = 0.798, n = 289), respectively. The regression equations between the first costal width (C1W) and either SCW or Wt were SCW = 3.223(C1W) 0.847 (R 2 = 0.919, n = 156) and Wt = 1.416 x 10 -2 (C1W) 2.426 (R 2 = 0.740, n = 133), respectively. There was no difference in slopes of the C1W-SCL relationship between wild and captive raised turtles as analyzed by ANCOVA. Thus, I pooled the group data and re-calculated the C1W and SCL relationship as SCL = 4.353(C1W) 0.848 (R 2 = 0.953, n = 340). This result indicated that SCL measurements could be estimated based on C1W measurements and that the C1W-SCL relationship could be applied to captive raised or wild hawksbills. It is clear that the SCL-SCW and C1W-SCW relationships were more similar to the relationship in the hawksbill turtles from Puerto Rican waters than to those captured in Australian waters, although there was no significant geographic difference between specimens from the Caribbean and Australian

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Reproductive ecology of the hawksbill turtle Eretmochelys imbricata in captivity

Kobayashi

Okuzawa²,

Soyano³

et al. 2010

NSUGAF

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In order to reveal the reproductive ecology of captive hawksbill caught from the wild, we investigated the mating and nesting behavior, clutch size, number of clutches and hatching rate from 2006 to 2009. We used a video camera system in order to determine the date and time of mating and nesting. Mean mating duration ranged from 50 to 150 minutes, and the period from mating to the 1 st nesting was 29.6±3.4 days. As for nesting, 4 fe- 25.2 eggs and 3.5±0.7 clutches, respectively. These results closely correlated with data from wild populations.Hatching rate of captive eggs was markedly lower compared to that of wild eggs. However, the straight carapace length and body weight of hatchlings in captivity were comparable to those of the wild ones.

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Variation of Size at Maturity of Female Hawksbill Turtles (<i>Eretmochelys imbricata</i>), with Speculations on Life-History Tactics Relative to Proper Stock Management

Cited by 3 publications

References 8 publications

Induction of Oviposition by the Administration of Oxytocin in Hawksbill Turtles

Induction of Oviposition by the Administration of Oxytocin in Hawksbill Turtles

Morphological Characteristics of the Carapace of the Hawksbill Turtle, Eretmochelys imbricata, from Cuban Waters

Reproductive ecology of the hawksbill turtle Eretmochelys imbricata in captivity

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