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.


Data obtained from a stranded 9.2 cm hawksbill indicate it resided at the ocean surface, immediately proximate the Main Hawaiian Islands. (A) Image of the turtle stranding from Feb 2015 near Waimea, Kauai (21.968°N, 159.672°W) during a period of exceptionally high surf. Gray area is the silhouetted outline of a presumably depredated left front flipper. Left hind flipper is present but not pictured. (B) Dry mass and (C) wet volume of gastrointestinal tract contents indicate a diet of floating plastic debris, algae, and terrestrial beetles from Kauai Island. White lines are y‐axis grid lines. (D) Complete inventory of 41 ingested plastic pieces, (E) tabulated for size‐color frequency each for both length and width. Bar color in (E) corresponds to color labels in (D). (F) 2014 survey records from hawksbill nesting beaches on Maui and Hawaii islands show peak hatchling emergences occurred during Sep–Oct, indicating this turtle was probably 3.4–5.3 months old.
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ece32034-fig-0003: Data obtained from a stranded 9.2 cm hawksbill indicate it resided at the ocean surface, immediately proximate the Main Hawaiian Islands. (A) Image of the turtle stranding from Feb 2015 near Waimea, Kauai (21.968°N, 159.672°W) during a period of exceptionally high surf. Gray area is the silhouetted outline of a presumably depredated left front flipper. Left hind flipper is present but not pictured. (B) Dry mass and (C) wet volume of gastrointestinal tract contents indicate a diet of floating plastic debris, algae, and terrestrial beetles from Kauai Island. White lines are y‐axis grid lines. (D) Complete inventory of 41 ingested plastic pieces, (E) tabulated for size‐color frequency each for both length and width. Bar color in (E) corresponds to color labels in (D). (F) 2014 survey records from hawksbill nesting beaches on Maui and Hawaii islands show peak hatchling emergences occurred during Sep–Oct, indicating this turtle was probably 3.4–5.3 months old.

Mentions: Figure 3 provides details from the 9.2 cm posthatchling that stranded near Waimea, Kauai (21.968°N, 159.672°W) in February 2015 during a period of strong surf. This is the only hawksbill in this cryptic life stage ever examined at necropsy (in 33 years of program operation, 1982–2015), and this presents a novel opportunity. Other than missing ~50% of its left front flipper (Fig. 3A), the turtle was visibly healthy, was given fluids and antibiotics by a veterinarian, yet died within 48 h. The complete gastrointestinal track including the esophagus, stomach, small intestine, and large intestine (Wyneken 2001) measured 57.4 cm. The first 37 cm, comprising all but the large intestine, were empty, while the remaining 20 cm were filled with a mix of pelagic algae, scarab beetles, and plastic debris (Fig. 3B–E). Figure 3B provides the contents by dry mass: 0.30 g plastic (60.5%), 0.16 g algae (33.2%), and 0.03 g beetles (6.3%). Figure 3C provides the wet volume contents: 8.1 mL algae (86.2%), 0.8 mL plastic (8.5%), and 0.5 mL beetles (5.3%). We identified two scarabs as Chinese rose beetles (Adoretus sinicus) which are an established invasive agricultural pest in the Hawaiian Islands (McQuate and Jameson 2011), particularly in Kauai. It is likely these beetles blew out onto the ocean from the adjacent agricultural fields in southern Kauai. We counted 41 pieces of plastic debris in the gut: 26 white (dimension ave = 3.1 mm, SD = 1.3), 5 blue (ave = 3.8 mm, SD = 2.5), 4 black (ave = 5.2 mm, SD = 1.3), 3 red (ave = 3.7 mm, SD = 1.2), with three additional fragments of monofilament fishing line (length ave = 16.3 mm, SD = 0.7). We did not trace the microplastic fragments further to their original items of use.


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)

Data obtained from a stranded 9.2 cm hawksbill indicate it resided at the ocean surface, immediately proximate the Main Hawaiian Islands. (A) Image of the turtle stranding from Feb 2015 near Waimea, Kauai (21.968°N, 159.672°W) during a period of exceptionally high surf. Gray area is the silhouetted outline of a presumably depredated left front flipper. Left hind flipper is present but not pictured. (B) Dry mass and (C) wet volume of gastrointestinal tract contents indicate a diet of floating plastic debris, algae, and terrestrial beetles from Kauai Island. White lines are y‐axis grid lines. (D) Complete inventory of 41 ingested plastic pieces, (E) tabulated for size‐color frequency each for both length and width. Bar color in (E) corresponds to color labels in (D). (F) 2014 survey records from hawksbill nesting beaches on Maui and Hawaii islands show peak hatchling emergences occurred during Sep–Oct, indicating this turtle was probably 3.4–5.3 months old.
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Related In: Results  -  Collection

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

ece32034-fig-0003: Data obtained from a stranded 9.2 cm hawksbill indicate it resided at the ocean surface, immediately proximate the Main Hawaiian Islands. (A) Image of the turtle stranding from Feb 2015 near Waimea, Kauai (21.968°N, 159.672°W) during a period of exceptionally high surf. Gray area is the silhouetted outline of a presumably depredated left front flipper. Left hind flipper is present but not pictured. (B) Dry mass and (C) wet volume of gastrointestinal tract contents indicate a diet of floating plastic debris, algae, and terrestrial beetles from Kauai Island. White lines are y‐axis grid lines. (D) Complete inventory of 41 ingested plastic pieces, (E) tabulated for size‐color frequency each for both length and width. Bar color in (E) corresponds to color labels in (D). (F) 2014 survey records from hawksbill nesting beaches on Maui and Hawaii islands show peak hatchling emergences occurred during Sep–Oct, indicating this turtle was probably 3.4–5.3 months old.
Mentions: Figure 3 provides details from the 9.2 cm posthatchling that stranded near Waimea, Kauai (21.968°N, 159.672°W) in February 2015 during a period of strong surf. This is the only hawksbill in this cryptic life stage ever examined at necropsy (in 33 years of program operation, 1982–2015), and this presents a novel opportunity. Other than missing ~50% of its left front flipper (Fig. 3A), the turtle was visibly healthy, was given fluids and antibiotics by a veterinarian, yet died within 48 h. The complete gastrointestinal track including the esophagus, stomach, small intestine, and large intestine (Wyneken 2001) measured 57.4 cm. The first 37 cm, comprising all but the large intestine, were empty, while the remaining 20 cm were filled with a mix of pelagic algae, scarab beetles, and plastic debris (Fig. 3B–E). Figure 3B provides the contents by dry mass: 0.30 g plastic (60.5%), 0.16 g algae (33.2%), and 0.03 g beetles (6.3%). Figure 3C provides the wet volume contents: 8.1 mL algae (86.2%), 0.8 mL plastic (8.5%), and 0.5 mL beetles (5.3%). We identified two scarabs as Chinese rose beetles (Adoretus sinicus) which are an established invasive agricultural pest in the Hawaiian Islands (McQuate and Jameson 2011), particularly in Kauai. It is likely these beetles blew out onto the ocean from the adjacent agricultural fields in southern Kauai. We counted 41 pieces of plastic debris in the gut: 26 white (dimension ave = 3.1 mm, SD = 1.3), 5 blue (ave = 3.8 mm, SD = 2.5), 4 black (ave = 5.2 mm, SD = 1.3), 3 red (ave = 3.7 mm, SD = 1.2), with three additional fragments of monofilament fishing line (length ave = 16.3 mm, SD = 0.7). We did not trace the microplastic fragments further to their original items of use.

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.