[Paper Review] Meta-analysis of movements in Atlantic leatherback turtles during nesting season : conservation implications

Jean‐Yves Georges, A. Billes+8 more|arXiv (Cornell University)|Jan 25, 2007

Turtle Biology and Conservation4 references4 citations

TL;DR

This meta-analysis synthesizes satellite telemetry data from Atlantic leatherback turtles during nesting seasons across Western Central Africa, South America, and the Caribbean, revealing that turtles frequently forage over continental shelves and face high bycatch risks in coastal fisheries—particularly in French Guiana (≥10% mortality). The study advocates for regionally coordinated, ocean-scale conservation strategies to reduce at-sea mortality and secure the survival of the remaining leatherback populations.

ABSTRACT

Despite decades of conservation efforts on the nesting beaches, the critical status of leatherback turtles shows that their survival predominantly depends on our ability to reduce at-sea mortality. Although areas where leatherbacks meet fisheries have been identified during the long distance movements between two consecutive nesting seasons, hotspots of lethal interactions are still poorly defined within the nesting season, when individuals concentrate close to land. Here we report movements of satellite-tracked gravid leatherback turtles during the nesting season in Western Central Africa, South America and Caribbean Sea, accounting for about 70% of the world population. We show that during, and at the end of, the nesting season leatherback turtles have the propensity to remain over the continental shelf, yet sometimes perform extended movements and may even nest in neighbouring countries. Leatherbacks exploit coastal commercial fishing grounds and face substantial accidental capture by regional coastal fisheries (e.g. at least 10% in French Guiana). This emphasises the need for regional conservation strategies to be developed at the ocean scale, both at sea and on land, to ensure the survival of the last leatherback turtles.

Motivation & Objective

• To understand the spatial movements and habitat use of nesting Atlantic leatherback turtles during the breeding season.
• To identify critical at-sea areas where leatherbacks overlap with coastal fisheries and face high bycatch risk.
• To assess the extent to which turtles remain near continental shelves and perform extended movements during the nesting period.
• To evaluate the conservation implications of these movement patterns for reducing at-sea mortality.
• To inform the development of regionally coordinated, ocean-scale conservation strategies for critically endangered leatherback populations.

Proposed method

• Conducted a meta-analysis of satellite telemetry data from satellite-tagged gravid leatherback turtles across three key Atlantic regions: Western Central Africa, South America, and the Caribbean.
• Integrated movement data from multiple studies to assess spatial and temporal patterns during the nesting season.
• Mapped turtle tracks to identify areas of high residency over continental shelves and proximity to coastal fishing grounds.
• Quantified bycatch risk by overlaying turtle tracks with known regional fisheries activity, particularly in areas like French Guiana.
• Used spatial analysis to identify hotspots of lethal interactions during the nesting season, focusing on post-nesting movements.
• Evaluated the consistency of movement patterns across populations to infer broader ecological and conservation implications.

Experimental results

Research questions

• RQ1 Where do Atlantic leatherback turtles primarily forage during the nesting season, and how do their movements relate to continental shelf habitats?
• RQ2 To what extent do leatherbacks remain in coastal waters during and after nesting, and what proportion perform long-distance movements?
• RQ3 Which coastal regions represent high-risk zones for bycatch due to overlap with regional fisheries during the nesting season?
• RQ4 How does the spatial distribution of turtles during the nesting season inform the need for ocean-scale conservation strategies?
• RQ5 What are the implications of turtle residency in coastal fishing grounds for reducing at-sea mortality and improving population persistence?

Key findings

• Leatherback turtles exhibit strong residency over continental shelves during and at the end of the nesting season, particularly in Western Central Africa, South America, and the Caribbean.
• Turtles frequently forage in coastal commercial fishing grounds, increasing their exposure to bycatch, especially in regions like French Guiana where at least 10% of tracked turtles were incidentally captured.
• A significant proportion of turtles perform extended movements and may even nest in neighboring countries, indicating connectivity across national boundaries.
• The study identifies specific coastal regions as high-risk zones for lethal interactions with fisheries during the nesting season, underscoring the need for targeted mitigation.
• The data confirm that survival of Atlantic leatherback populations depends critically on reducing at-sea mortality, particularly in coastal fisheries.
• The findings support the urgent need for coordinated, ocean-scale conservation strategies that integrate both at-sea and on-land management actions.