Limits...
The developmental biogeography of hawksbill sea turtles in the North Pacific.

Van Houtan KS, Francke DL, Alessi S, Jones TT, Martin SL, Kurpita L, King CS, Baird RW - Ecol Evol (2016)

Bottom Line: This knowledge gap limits the effectiveness of conservation management for this globally endangered species.We find hawksbills 0-4 years of age, measuring 8-34 cm straight carapace length, are found predominantly in the coastal pelagic waters of Hawaii.This focuses attention on hazards in these ecosystems - entanglement and ingestion of marine debris - and perhaps away from longline bycatch and decadal climate regimes that affect sea turtle development in oceanic regions.

View Article: PubMed Central - PubMed

Affiliation: NOAA FisheriesPacific Islands Fisheries Science CenterHonoluluHawaii96818; Nicholas School of the EnvironmentDuke UniversityDurhamNorth Carolina27708; Present address: Monterey Bay AquariumMontereyCalifornia93940.

ABSTRACT
High seas oceanic ecosystems are considered important habitat for juvenile sea turtles, yet much remains cryptic about this important life-history period. Recent progress on climate and fishery impacts in these so-called lost years is promising, but the developmental biogeography of hawksbill sea turtles (Eretmochelys imbricata) has not been widely described in the Pacific Ocean. This knowledge gap limits the effectiveness of conservation management for this globally endangered species. We address this with 30 years of stranding observations, 20 years of bycatch records, and recent simulations of natal dispersal trajectories in the Hawaiian Archipelago. We synthesize the analyses of these data in the context of direct empirical observations, anecdotal sightings, and historical commercial harvests from the insular Pacific. We find hawksbills 0-4 years of age, measuring 8-34 cm straight carapace length, are found predominantly in the coastal pelagic waters of Hawaii. Unlike other species, we find no direct evidence of a prolonged presence in oceanic habitats, yet satellite tracks of passive drifters (simulating natal dispersal) and our small sample sizes suggest that an oceanic phase for hawksbills cannot be dismissed. Importantly, despite over 600 million hooks deployed and nearly 6000 turtle interactions, longline fisheries have never recorded a single hawksbill take. We address whether the patterns we observe are due to population size and gear selectivity. Although most sea turtle species demonstrate clear patterns of oceanic development, hawksbills in the North Pacific may by contrast occupy a variety of ecosystems including coastal pelagic waters and shallow reefs in remote atolls. This focuses attention on hazards in these ecosystems - entanglement and ingestion of marine debris - and perhaps away from longline bycatch and decadal climate regimes that affect sea turtle development in oceanic regions.

No MeSH data available.


Related in: MedlinePlus

Three in‚Äźwater, anecdotal observations of early life‚Äźhistory hawksbills. Small juvenile hawksbill turtles seen at the ocean surface (A) 13¬†km off Hawaii Island at 2450¬†m depth, (B) 47 km off Hawaii Island at 4600 m depth near the Alika Knoll (credit: D. Webster/Cascadia Research). Both turtle lengths estimated at 28¬†cm SCL. Notice the plentiful debris field floating near the turtle. (C) Small juvenile hawksbill seen foraging in the shallow lagoon of Rose Atoll, a remote oceanic coral pinnacle located 260¬†km east of the Tutuila Island, American Samoa (credit: K. Van Houtan/NOAA). This turtle was later hand‚Äźcaptured and measured at 27.4¬†cm SCL. Remora fish, Pelanes crabs, and Lepas barnacles (only C) were documented on these turtles, which are common pelagic epibionts. Scale bar in all images is 5¬†cm.
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ece32034-fig-0005: Three in‚Äźwater, anecdotal observations of early life‚Äźhistory hawksbills. Small juvenile hawksbill turtles seen at the ocean surface (A) 13¬†km off Hawaii Island at 2450¬†m depth, (B) 47 km off Hawaii Island at 4600 m depth near the Alika Knoll (credit: D. Webster/Cascadia Research). Both turtle lengths estimated at 28¬†cm SCL. Notice the plentiful debris field floating near the turtle. (C) Small juvenile hawksbill seen foraging in the shallow lagoon of Rose Atoll, a remote oceanic coral pinnacle located 260¬†km east of the Tutuila Island, American Samoa (credit: K. Van Houtan/NOAA). This turtle was later hand‚Äźcaptured and measured at 27.4¬†cm SCL. Remora fish, Pelanes crabs, and Lepas barnacles (only C) were documented on these turtles, which are common pelagic epibionts. Scale bar in all images is 5¬†cm.

Mentions: Beyond stranding observations, two 28¬†cm juvenile hawksbills have recently been documented off the Kona (west) coast of Hawaii Island. Both turtles were seen swimming freely at the ocean surface during a regular coastal cetacean survey by the Cascadia Research Collective (e.g., Baird et¬†al. 2013; also see Appendix¬†S1). One turtle was observed in May 2011 for <1¬†min, 13¬†km offshore, in waters 2450¬†m deep (Fig.¬†5A). A second turtle was observed in November 2015 for about the same duration, but 47¬†km offshore, at 4600¬†m depth, and near an oceanographic feature known as the Alika Knoll (Fig.¬†5B). Outside of the strandings, these are the only such records of juvenile hawksbills offshore in Hawaii. Additionally, three small juvenile hawksbills (35‚Äď46¬†cm) have been recently recorded in nearshore reefs of remote NWHI atolls (Van Houtan et¬†al. 2012) and juvenile hawksbills in this cryptic life‚Äźhistory stage have been observed with some frequency in the shallow lagoon of Rose Atoll, American Samoa (Fig.¬†5B, Pfaller et¬†al. 2014). Of the latter group, one turtle was captured and measured at 27.4¬†cm SCL and was one of numerous small juvenile hawksbills seen in the Rose Atoll lagoon.


The developmental biogeography of hawksbill sea turtles in the North Pacific.

Van Houtan KS, Francke DL, Alessi S, Jones TT, Martin SL, Kurpita L, King CS, Baird RW - Ecol Evol (2016)

Three in‚Äźwater, anecdotal observations of early life‚Äźhistory hawksbills. Small juvenile hawksbill turtles seen at the ocean surface (A) 13¬†km off Hawaii Island at 2450¬†m depth, (B) 47 km off Hawaii Island at 4600 m depth near the Alika Knoll (credit: D. Webster/Cascadia Research). Both turtle lengths estimated at 28¬†cm SCL. Notice the plentiful debris field floating near the turtle. (C) Small juvenile hawksbill seen foraging in the shallow lagoon of Rose Atoll, a remote oceanic coral pinnacle located 260¬†km east of the Tutuila Island, American Samoa (credit: K. Van Houtan/NOAA). This turtle was later hand‚Äźcaptured and measured at 27.4¬†cm SCL. Remora fish, Pelanes crabs, and Lepas barnacles (only C) were documented on these turtles, which are common pelagic epibionts. Scale bar in all images is 5¬†cm.
© Copyright Policy - creativeCommonsBy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4834323&req=5

ece32034-fig-0005: Three in‚Äźwater, anecdotal observations of early life‚Äźhistory hawksbills. Small juvenile hawksbill turtles seen at the ocean surface (A) 13¬†km off Hawaii Island at 2450¬†m depth, (B) 47 km off Hawaii Island at 4600 m depth near the Alika Knoll (credit: D. Webster/Cascadia Research). Both turtle lengths estimated at 28¬†cm SCL. Notice the plentiful debris field floating near the turtle. (C) Small juvenile hawksbill seen foraging in the shallow lagoon of Rose Atoll, a remote oceanic coral pinnacle located 260¬†km east of the Tutuila Island, American Samoa (credit: K. Van Houtan/NOAA). This turtle was later hand‚Äźcaptured and measured at 27.4¬†cm SCL. Remora fish, Pelanes crabs, and Lepas barnacles (only C) were documented on these turtles, which are common pelagic epibionts. Scale bar in all images is 5¬†cm.
Mentions: Beyond stranding observations, two 28¬†cm juvenile hawksbills have recently been documented off the Kona (west) coast of Hawaii Island. Both turtles were seen swimming freely at the ocean surface during a regular coastal cetacean survey by the Cascadia Research Collective (e.g., Baird et¬†al. 2013; also see Appendix¬†S1). One turtle was observed in May 2011 for <1¬†min, 13¬†km offshore, in waters 2450¬†m deep (Fig.¬†5A). A second turtle was observed in November 2015 for about the same duration, but 47¬†km offshore, at 4600¬†m depth, and near an oceanographic feature known as the Alika Knoll (Fig.¬†5B). Outside of the strandings, these are the only such records of juvenile hawksbills offshore in Hawaii. Additionally, three small juvenile hawksbills (35‚Äď46¬†cm) have been recently recorded in nearshore reefs of remote NWHI atolls (Van Houtan et¬†al. 2012) and juvenile hawksbills in this cryptic life‚Äźhistory stage have been observed with some frequency in the shallow lagoon of Rose Atoll, American Samoa (Fig.¬†5B, Pfaller et¬†al. 2014). Of the latter group, one turtle was captured and measured at 27.4¬†cm SCL and was one of numerous small juvenile hawksbills seen in the Rose Atoll lagoon.

Bottom Line: This knowledge gap limits the effectiveness of conservation management for this globally endangered species.We find hawksbills 0-4 years of age, measuring 8-34 cm straight carapace length, are found predominantly in the coastal pelagic waters of Hawaii.This focuses attention on hazards in these ecosystems - entanglement and ingestion of marine debris - and perhaps away from longline bycatch and decadal climate regimes that affect sea turtle development in oceanic regions.

View Article: PubMed Central - PubMed

Affiliation: NOAA FisheriesPacific Islands Fisheries Science CenterHonoluluHawaii96818; Nicholas School of the EnvironmentDuke UniversityDurhamNorth Carolina27708; Present address: Monterey Bay AquariumMontereyCalifornia93940.

ABSTRACT
High seas oceanic ecosystems are considered important habitat for juvenile sea turtles, yet much remains cryptic about this important life-history period. Recent progress on climate and fishery impacts in these so-called lost years is promising, but the developmental biogeography of hawksbill sea turtles (Eretmochelys imbricata) has not been widely described in the Pacific Ocean. This knowledge gap limits the effectiveness of conservation management for this globally endangered species. We address this with 30 years of stranding observations, 20 years of bycatch records, and recent simulations of natal dispersal trajectories in the Hawaiian Archipelago. We synthesize the analyses of these data in the context of direct empirical observations, anecdotal sightings, and historical commercial harvests from the insular Pacific. We find hawksbills 0-4 years of age, measuring 8-34 cm straight carapace length, are found predominantly in the coastal pelagic waters of Hawaii. Unlike other species, we find no direct evidence of a prolonged presence in oceanic habitats, yet satellite tracks of passive drifters (simulating natal dispersal) and our small sample sizes suggest that an oceanic phase for hawksbills cannot be dismissed. Importantly, despite over 600 million hooks deployed and nearly 6000 turtle interactions, longline fisheries have never recorded a single hawksbill take. We address whether the patterns we observe are due to population size and gear selectivity. Although most sea turtle species demonstrate clear patterns of oceanic development, hawksbills in the North Pacific may by contrast occupy a variety of ecosystems including coastal pelagic waters and shallow reefs in remote atolls. This focuses attention on hazards in these ecosystems - entanglement and ingestion of marine debris - and perhaps away from longline bycatch and decadal climate regimes that affect sea turtle development in oceanic regions.

No MeSH data available.


Related in: MedlinePlus