Better Science Needed for Restoration in the Gulf of Mexico

Bjorndal, Karen A.; Bowen, Brian W.; Chaloupka, Milani; Crowder, Larry B.; Heppell, Selina S.; Jones, Cynthia M.; Lutcavage, Molly E.; Policansky, David; Solow, Andrew R.; Witherington, Blair E.

doi:10.1126/science.1199935

Cited by 69 publications

(49 citation statements)

References 20 publications

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“…protection efforts and conservation planning for sea turtles, we measured the importance of surfacepelagic habitat occupied by post-hatchling and early juvenile sea turtles in the western North Atlantic and Gulf of Mexico. In 2010, assessments of sea turtle habitat use in the Gulf of Mexico were shown to be critically lacking when Gulf waters received the largest offshore oil spill ever recorded (Camilli et al 2010, Bjorndal et al 2011. Spill-response (turtle rescue) data (NOAA 2012a) show that this spill was particularly harmful to the sea turtle life stage and surface-pelagic habitat we describe here.…”

Section: Introductionmentioning

confidence: 83%

Young sea turtles of the pelagic Sargassum-dominated drift community: habitat use, population density, and threats

Witherington¹,

Hirama²,

Hardy³

2012

Mar. Ecol. Prog. Ser.

197

183

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Section: Introductionmentioning

confidence: 83%

Young sea turtles of the pelagic Sargassum-dominated drift community: habitat use, population density, and threats

Witherington¹,

Hirama²,

Hardy³

2012

Mar. Ecol. Prog. Ser.

197

183

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“…AgeSM greatly influences long-term population growth rates and the response of populations to perturbations (Heppell et al 2003). Estimation of AgeSM in sea turtles is challenging because the age of live sea turtles cannot be determined, and sea turtles undertake extensive movements during a long immature period (Bjorndal et al 2011).…”

Section: Introductionmentioning

confidence: 99%

Variation in age and size at sexual maturity in Kemp’s ridley sea turtles

Bjorndal¹,

Parsons²,

Mustin³

et al. 2014

Endang. Species. Res.

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Age at sexual maturity (AgeSM) is one of the most serious demographic data gaps for sea turtle populations. Better estimates of AgeSM and associated variance would improve evaluation of population dynamics and responses of populations to disturbances and conservation measures. A population of Kemp's ridleys Lepidochelys kempii was raised in captivity under the same conditions from hatchlings to several years after maturity. Data collected from 14 female Kemp's ridleys at Cayman Turtle Farm over a 16 yr period allowed us to determine mean and variance in age, length, mass, and body condition at maturity, average pre-maturity growth rates, and post-maturity growth rates, as well as interactions among these parameters. Age, length, and mass at maturity exhibited considerable variance, with ranges of 5 to 12 yr, 47.0 to 61.0 cm, and 20.0 to 36.8 kg, respectively. Pre-maturity length growth rate is the best single predictor of AgeSM, accounting for 87% of the variation in AgeSM. Pre-maturity mass growth rate is the best single predictor of size at maturity, accounting for 51 and 65% of variation in length at maturity and mass at maturity, respectively. Although estimates of age and size at maturity from captive Kemp's ridleys cannot be applied to wild populations because of the effect of nutrition, the amount of variation around age and size at maturity in Kemp's ridleys from Cayman Turtle Farm is a good first approximation of inherent (or genetic) variation in these parameters for wild Kemp's ridleys. Population models for Kemp's ridleys that now employ a knife-edge estimate of AgeSM would be improved by incorporating a maturity schedule that reflects the variation in AgeSM.KEY WORDS: Age at sexual maturity · Size at sexual maturity · Indeterminate growth · Lepidochelys kempii · Sea turtle Resale or republication not permitted without written consent of the publisherEndang Species Res 25: 57-67, 2014 This variation is primarily a result of variation in LengthSM and not of growth after sexual maturity, because growth rates are largely negligible after maturity (Carr & Goodman 1970, Bjorndal et al. 1983, 2013a, Broderick et al. 2003, Price et al. 2004. Whether the variation in LengthSM is a result of inherent (or genetic) variation or environmental factors is not known. Whatever the cause, selection of an appropriate population-wide LengthSM for estimating AgeSM is problematic. Several measures have been used; minimum size and mean size of nesting females are the most common.A few records of AgeSM in sea turtles have resulted from marking hatchlings so they can be recognized at maturity or by tagging head-started turtles -turtles that have been reared in captivity usually for a year before release (Bell et al. 2005, Shaver & Wibbels 2007, Limpus 2009). Individual records of age at sexual maturity are very valuable and are not known for most populations. However, as these rare estimates trickle in, the extent to which they can be used to represent population estimates depends upon the amount of variation i...

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“…However, this segment of the population represents a very small portion of the sea turtle population, and determining population sizes of sea turtles, as well as quantifying impacts on juvenile and adult males and females, is extremely challenging (NRC 2010). This type of population assessment is similar to estimating human population trends by counting women in maternity wards: while useful information is obtained, if the children were decimated from an impact, the mortality would not be detected in the adult population for decades (Bjorndal et al 2011). The need for assessing populations of both juvenile and adult sea turtles in the water to complement assessments of nesting beaches has been widely recognized (Magnuson et al 1990;TEWG 1998TEWG , 2000.…”

mentioning

confidence: 99%