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.


Proximity of hawksbill strandings to the Hawaii coastline across all life stages. Most size classes strand within 100 m of the low tide line in nearshore neritic habitat. The lone exception is turtles in the 8–34 cm class that are commonly observed >1 km from the coast. Black circles are average class distance, bars are standard error, and orange region is the 95% confidence interval for all groups, save the 8–34 cm turtles. For each size class, n ≥ 10, representing 129 hawksbill strandings from 1984 to 2015.
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ece32034-fig-0001: Proximity of hawksbill strandings to the Hawaii coastline across all life stages. Most size classes strand within 100 m of the low tide line in nearshore neritic habitat. The lone exception is turtles in the 8–34 cm class that are commonly observed >1 km from the coast. Black circles are average class distance, bars are standard error, and orange region is the 95% confidence interval for all groups, save the 8–34 cm turtles. For each size class, n ≥ 10, representing 129 hawksbill strandings from 1984 to 2015.

Mentions: Figure 1 plots the distance stranded from shore for 128 Hawaii hawksbills throughout ontogeny. Hatchlings (3.0–7.9 cm, n = 42), juveniles (35.0–74.4 cm, n = 52), and adults (74.5–90.0 cm, n = 20) are nearshore, stranding within 30 m of the coast. The cryptic stage (8.0–34.9 cm, n = 15), however, has been documented stranding offshore in pelagic waters proximate the archipelago, and this particular data point and its entire error interval is outside the confidence interval from the other size classes. Three turtles documented >1 km offshore, in particular, measured 13, 27, and 31 cm and were all released from fishing gear entanglements near Hawaii, Maui, and Molokai islands, respectively. One additional turtle excluded from this analysis (due to time and therefore distance drifted since death) was a highly decomposed 30.7 cm juvenile recovered from a derelict fishing net at sea (21.981°N, 167.000°W) roughly 200 km SSW from FFS in the NWHI.


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)

Proximity of hawksbill strandings to the Hawaii coastline across all life stages. Most size classes strand within 100 m of the low tide line in nearshore neritic habitat. The lone exception is turtles in the 8–34 cm class that are commonly observed >1 km from the coast. Black circles are average class distance, bars are standard error, and orange region is the 95% confidence interval for all groups, save the 8–34 cm turtles. For each size class, n ≥ 10, representing 129 hawksbill strandings from 1984 to 2015.
© Copyright Policy - creativeCommonsBy
Related In: Results  -  Collection

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

ece32034-fig-0001: Proximity of hawksbill strandings to the Hawaii coastline across all life stages. Most size classes strand within 100 m of the low tide line in nearshore neritic habitat. The lone exception is turtles in the 8–34 cm class that are commonly observed >1 km from the coast. Black circles are average class distance, bars are standard error, and orange region is the 95% confidence interval for all groups, save the 8–34 cm turtles. For each size class, n ≥ 10, representing 129 hawksbill strandings from 1984 to 2015.
Mentions: Figure 1 plots the distance stranded from shore for 128 Hawaii hawksbills throughout ontogeny. Hatchlings (3.0–7.9 cm, n = 42), juveniles (35.0–74.4 cm, n = 52), and adults (74.5–90.0 cm, n = 20) are nearshore, stranding within 30 m of the coast. The cryptic stage (8.0–34.9 cm, n = 15), however, has been documented stranding offshore in pelagic waters proximate the archipelago, and this particular data point and its entire error interval is outside the confidence interval from the other size classes. Three turtles documented >1 km offshore, in particular, measured 13, 27, and 31 cm and were all released from fishing gear entanglements near Hawaii, Maui, and Molokai islands, respectively. One additional turtle excluded from this analysis (due to time and therefore distance drifted since death) was a highly decomposed 30.7 cm juvenile recovered from a derelict fishing net at sea (21.981°N, 167.000°W) roughly 200 km SSW from FFS in the NWHI.

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.