Oceanic residents, neritic migrants: a possible mechanism underlying foraging dichotomy in adult female loggerhead turtles (Caretta caretta)

Hatase, Hideo; Omuta, Kazuyoshi; Tsukamoto, Katsumi

doi:10.1007/s00227-010-1413-9

Cited by 51 publications

(71 citation statements)

References 43 publications

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“…Both of these characteristics are certain to facilitate the continued use of these oceanic habitats during the adult stage. However, the data presented here demonstrate that the neritic foragers nesting in Cape Verde are larger and lay more eggs than the oceanic foragers and similar results have been reported from Japan (Hatase et al 2010). Certainly, the smaller oceanic females could overcome their smaller clutch size by producing more clutches per season and/or by employing the shorter remigration intervals associated with the shorter migration distance between their foraging habitats and their nesting sites, but this hypothesis should be evaluated by future research.…”

Section: Discussionsupporting

confidence: 79%

“…Generally, these less productive habitats are oceanic, but small adult females may sometimes also be found in neritic habitats (Hatase et al 2002, Hawkes et al 2006, Zbinden et al 2011. These differences in size may not be related to differences in age as oceanic and neritic foragers were suggested to reach maturity and begin reproduction at similar ages (Hatase et al 2010).…”

Section: Abstract: Sea Turtles · Foraging Strategies · Stable Isotopmentioning

confidence: 99%

“…It is probable that turtles exploiting less productive habitats will grow more slowly than turtles exploiting more productive habitats (Hatase et al 2010;McClellan et al 2010, Piovano et al 2011. Furthermore, clutch size is known to increase with female body size (Broderick et al 2003) and female turtles exploiting the less productive feeding grounds, therefore, lay smaller clut ches (Hatase et al 2010, Zbinden et al 2011.…”

Section: Abstract: Sea Turtles · Foraging Strategies · Stable Isotopmentioning

confidence: 99%

“…In this scenario, oceanic foraging offers less profitability and reproductive output than neritic foraging, being, therefore, suboptimal. Accordingly, most of the fe males nesting in Japan, the central Mediterranean and the northwestern Atlantic are neritic (Hawkes et al 2007, Hatase et al 2010, Zbinden et al 2011. However, the opposite pattern seems to hold for Cape Verde and Oman, although the published information refers only to a handful of satellite-tracked females from each population (Hawkes et al 2006, Rees et al 2010.…”

Section: Abstract: Sea Turtles · Foraging Strategies · Stable Isotopmentioning

confidence: 99%

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Foraging dichotomy in loggerhead sea turtles Caretta caretta off northwestern Africa

Eder¹,

Ceballos²,

Martins³

et al. 2012

Mar. Ecol. Prog. Ser.

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Section: Discussionsupporting

confidence: 79%

Section: Abstract: Sea Turtles · Foraging Strategies · Stable Isotopmentioning

confidence: 99%

Section: Abstract: Sea Turtles · Foraging Strategies · Stable Isotopmentioning

confidence: 99%

Section: Abstract: Sea Turtles · Foraging Strategies · Stable Isotopmentioning

confidence: 99%

See 2 more Smart Citations

Foraging dichotomy in loggerhead sea turtles Caretta caretta off northwestern Africa

Eder¹,

Ceballos²,

Martins³

et al. 2012

Mar. Ecol. Prog. Ser.

View full text Add to dashboard Cite

“…Because growth in sea turtles is negligible once reproductive maturity is reached (Carr & Goodman 1970, Broderick et al 2003, Limpus & Limpus 2003, it is possible that individuals foraging in neritic habitats mature earlier and/or at larger sizes than those foraging in oceanic habitats (Hatase et al 2002, Hawkes et al 2006. First-time neritic nesters were significantly larger than oceanic nesters at Yakushima Island, Japan, and a promising new aging technique suggested they were of similar ages (Hatase et al 2010).Though not yet tested empirically, a reasonable hypothesis is that larger, neritic-foraging nesters may have greater lifetime reproductive output because they mature earlier and fecundity increases with size in loggerheads (Frazer & Richardson 1986, Tiwari & Bjorndal 2000, Broderick et al 2003.Juvenile loggerheads in the North Pacific leave their Japanese rookeries as hatchlings and are known to frequent 2 regions, the oceanic Central North Pacific (CNP) and neritic habitats of the Baja California Peninsula, Mexico (BCP). Because the oceanographic factors that produce prey in the 2 regions are different (Espinosa-Carreon et al 2004, Legaard & Thomas 2006, Palacios et al 2006, Polovina et al 2006, patterns of prey abundance and quality also differ between these regions.…”

mentioning

confidence: 99%

Demographic implications of alternative foraging strategies in juvenile loggerhead turtles Caretta caretta of the North Pacific Ocean

Peckham¹,

Díaz²,

Tremblay³

et al. 2011

Mar. Ecol. Prog. Ser.

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To assess the potential demographic consequences of alternative juvenile foraging strategies in loggerhead sea turtles Caretta caretta, we compared habitat selection, movement, size frequency, and diet of juvenile loggerheads in neritic versus oceanic habitats of the North Pacific. Forty juveniles satellite-tracked from neritic habitat revealed utilization distributions 2 orders of magnitude smaller than those of 26 juveniles of the same size class tracked for similar durations from oceanic habitat. Oceanic juveniles traveled significantly further, faster and straighter, experienced lower sea surface temperature and productivity, and consumed prey of much lower energy density, strongly suggesting that the neritic foraging strategy is energetically favorable. These findings combined with those from other studies suggest that the neritic strategy would result in higher growth and eventually higher fecundity. Manipulation of a loggerhead demographic model indicated that small disadvantages in survivorship for neritic juveniles could balance the relatively large advantages in growth and fecundity of the neritic strategy. The oceanic strategy may persist as a slower but safer life history strategy. Our findings underscore the importance of elucidating variation in the ecology and corresponding vital rates of juveniles for modeling, managing, and conserving migratory megafaunal populations. KEY WORDS: Demography · Ontogeny · Diet · Juvenile · Migration · Habitat use · Utilization distributions Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 425: [269][270][271][272][273][274][275][276][277][278][279][280] 2011 Smith 1995, Bolnick et al. 2003). Variation in the foraging strategies of juveniles and their resulting vital rates could have profound implications for the demography and conservation of migratory megafauna.Loggerhead turtles Caretta caretta exhibit several life history patterns that make them useful subjects for examining the effects of alternative foraging strategies. During their long juvenile life stage, which lasts upwards of 3 decades (Snover 2002, Heppell et al. 2003, these individuals are opportunistically omnivorous and capable of transoceanic movements. They have no parental care or social structure and they are not tied to a central location for reproduction, enabling them to choose from an ocean-wide range of habitats (Bolten 2003). As juveniles, loggerheads use both oceanic and neritic habitats (Pitman 1990, Polovina et al. 2000, Bolten 2003, McClellan & Read 2007.In the Atlantic Ocean, Caretta caretta have long been thought to undergo an ontogenetic habitat shift from oceanic to neritic habitats upon reaching a size threshold of ~48 cm (Carr 1987, Bolten 2003, though recent data support more flexibility in the large juvenile stage. Based on annual ring spacing in sectioned humeri, Snover (2002) found that large juvenile loggerheads in the Atlantic may experience as much as a 30% increase in growth rates after shifting from oceanic to ner...

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Identifying the foraging grounds of the new loggerhead turtle nesters in the western Mediterranean

Cardona,

Abalo‐Morla,

Cani

et al. 2024

Aquatic Conservation

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The western Mediterranean Sea has traditionally served as a primary foraging ground for juvenile loggerhead turtles from three distinct regional management units: the North‐western Atlantic, the Mediterranean and Cape Verde. Nesting activities were sporadic. Recently, nesting activity on the beaches of eastern Spain has increased, due to warmer sand and water temperatures during the summer months. The study has integrated stable isotope analysis of carbon (C), nitrogen (N) and sulphur (S) with satellite telemetry to identify the foraging grounds of these new colonizers nesting on Spanish beaches. Results indicate that the majority of these adult females forage oceanically in the Algerian Basin, with a few exhibiting distinct stable isotope signals, tentatively associated with foraging in shallow coastal areas in the central Mediterranean Sea. The dominance of oceanic foragers in this new population is noteworthy, given the Algerian Basin's oligotrophic nature. This contrasts with the prevalence of neritic foraging in adult females nesting in the central and eastern Mediterranean Sea. The use of the Algerian Basin as a foraging ground for adult loggerhead turtles exposes them to bycatch from drifting longlines. The authorities should refrain from increasing bluefin quotas imposed on longliners in the Algerian Basin unless the fishery avoids using squid as bait and agrees to deploy hooks deeper than 25 m to reduce loggerhead turtle bycatch.

show abstract

Oceanic residents, neritic migrants: a possible mechanism underlying foraging dichotomy in adult female loggerhead turtles (Caretta caretta)

Cited by 51 publications

References 43 publications

Foraging dichotomy in loggerhead sea turtles Caretta caretta off northwestern Africa

Foraging dichotomy in loggerhead sea turtles Caretta caretta off northwestern Africa

Demographic implications of alternative foraging strategies in juvenile loggerhead turtles Caretta caretta of the North Pacific Ocean

Identifying the foraging grounds of the new loggerhead turtle nesters in the western Mediterranean

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