Oceanographic influences on the dive behavior of juvenile loggerhead turtles (Caretta caretta) in the North Pacific Ocean

Howell, Evan A.; Dutton, Peter H.; Polovina, Jeffrey J.; Bailey, Helen; Parker, Denise M.; Balazs, George H.

doi:10.1007/s00227-009-1381-0

Cited by 52 publications

(60 citation statements)

References 40 publications

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“…Howell et al (2010) reported that CNP juvenile loggerheads spent over 80% of their time within 5 m of the surface, presumably reflecting their consumption of neustonic prey. Comprehensive dive data have not been collected for loggerheads at BCP, but diet composition suggests that they can forage on or near the benthos.…”

Section: Discussionmentioning

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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Section: Discussionmentioning

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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“…It is possible that the home range of some of our photographed turtles does not occur in regularly surveyed areas, or that we have encountered animals in the periphery of their home ranges. Greens and loggerheads modify their home range both spatially and temporarily depending on resource availability, environmental conditions (e.g., temperature, depth, productivity of waters) or diurnal patterns (Luschi et al, 2006;Howell et al, 2010;Dalleau et al, 2014;Shimada, 2015;Christiansen et al, 2016;Varo-Cruz et al, 2016). The general behavioral-ecological model for Cheloniidae is a gradual shift from pelagic-vagile to benthic-sedentary lifestyle with progressive reduction of home ranges (Godley et al, 2008;Casale et al, 2012), with strong site fidelity evident in some populations (Shimada et al, 2016).…”

Section: Predictors Of Turtle Abundancementioning

confidence: 99%

Spatial Distribution and Residency of Green and Loggerhead Sea Turtles Using Coastal Reef Habitats in Southern Mozambique

et al. 2017

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Sea turtles spend the majority of their immature and adult lives in foraging grounds, yet few studies have examined their abundance and condition in these areas when compared to more accessible nesting beach habitats. Here, a 5-year dive log, photo-identification (photo-ID) and surface encounter datasets were used to investigate the abundance, individual movements and distribution of sea turtles along 40 km of coastal reefs in southern Mozambique. A generalized linear model (GLM) was constructed with turtle sightings as the response variable. Habitat type, year and day of the year, as well as underwater visibility, were significant predictors of turtle sightings. However, only 8% of the total variance was explained by the model, indicating that other variables have a significant influence on turtle movement and distribution. Photo-ID differentiated 22 individual green turtles Chelonia mydas and 42 loggerhead turtles Caretta caretta from 323 photo-ID encounters. A majority (64%) of the photos could be used to identify the individual. Although residency times of up to 1152 days were calculated for juvenile green turtles, a low overall resighting rate indicates that individual turtles either had large home ranges or were transient to the area. Surface encounter data revealed a preference for nearshore shallow waters and an increased abundance close to reef systems. Sea turtles' preferences for shallow, nearshore habitats are likely to increase the encounter risk with opportunistic and targeted artisanal fishers who catch sea turtles.

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“…Mar Ecol Prog Ser 433: [261][262][263][264][265][266][267][268][269][270][271][272] 2011 been linked through genetic analyses and satellite tracking to aggregations of juveniles and subadults found in the central and eastern Pacific (Bowen 1995, Nichols et al 2000, Polovina et al 2006, Howell et al 2010. In the South Pacific Ocean, decades of intense monitoring in eastern Australia has helped in defining many aspects of the nesting and oceanic ecology of loggerhead turtles in the western South Pacific region and in describing declining trends in abundance of that population (Limpus & Limpus 2003a).…”

Section: Resale or Republication Not Permitted Without Written Consenmentioning

confidence: 99%

Post-capture movements of loggerhead turtles in the southeastern Pacific Ocean assessed by satellite tracking

Mangel

Alfaro‐Shigueto²,

Witt³

et al. 2011

Mar. Ecol. Prog. Ser.

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The post-capture movements made by loggerhead sea turtles Caretta caretta in the southeastern Pacific Ocean were monitored from 2003 to 2007. Fourteen loggerhead turtles were fitted with satellite transmitters and released off the coast of Peru. All turtles were juveniles (curved carapace length range: 40.5 to 68.5 cm) incidentally captured by small-scale longline fishing vessels from southern or central Peru. Track durations were highly variable (mean ± SD: 143 ± 90 d; range: 8 to 297 d) with no clear signs of immediate post-release mortality. Upon release, all turtles moved offshore beyond the continental shelf. Eight of 11 turtles tracked for > 60 d had final displacements of < 750 km, suggesting that loggerhead turtles often maintain extended residency in these waters and that this area is an important foraging zone for loggerhead turtles of southwest Pacific origin. Satellite tracks also showed a substantial overlap of areas used by turtles with known Peruvian longline fishing effort. Turtles spent 75% of their time within the area fished by this fleet (based upon observed sets). This suggests that turtles are vulnerable to fishery interactions and that bycatch mitigation measures should be employed to minimize fishery impacts on loggerhead turtles. The loggerhead turtles tracked during this study spent ca. 51% of their time in Peruvian waters, 39% in international waters and 9% in Chilean waters, which emphasizes the need for a multinational approach to sea turtle conservation and fisheries management in the region.KEY WORDS: Caretta caretta · Peru · Chile · Small-scale fisheries · Bycatch · Habitat · Governance Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 433: [261][262][263][264][265][266][267][268][269][270][271][272] 2011 been linked through genetic analyses and satellite tracking to aggregations of juveniles and subadults found in the central and eastern Pacific (Bowen 1995, Nichols et al. 2000, Polovina et al. 2006, Howell et al. 2010. In the South Pacific Ocean, decades of intense monitoring in eastern Australia has helped in defining many aspects of the nesting and oceanic ecology of loggerhead turtles in the western South Pacific region and in describing declining trends in abundance of that population (Limpus & Limpus 2003a). However, it was not until 2004 that the species was confirmed in the southeastern Pacific Ocean (SEP) through a combination of onboard and shore-based fisheries monitoring (Alfaro-Shigueto et al. 2004). Genetic studies have shown that the juvenile loggerhead turtles found in the SEP originate from Australian and New Caledonian rookeries (Alfaro-Shigueto et al. 2004, Boyle et al. 2009). Additional reports now also confirm the occurrence of loggerhead turtles off Ecuador and Columbia (Alava 2008) and Chile to a latitude of 32° S (Donoso & Dutton 2010). Alfaro-Shigueto et al. (2008) report primarily small-to medium-sized juveniles and subadultsized turtles found off the Peruvian coast (curved carapace length [CCL]...

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Oceanographic influences on the dive behavior of juvenile loggerhead turtles (Caretta caretta) in the North Pacific Ocean

Cited by 52 publications

References 40 publications

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

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

Spatial Distribution and Residency of Green and Loggerhead Sea Turtles Using Coastal Reef Habitats in Southern Mozambique

Post-capture movements of loggerhead turtles in the southeastern Pacific Ocean assessed by satellite tracking

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