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Recovery Strategy for the Leatherback Turtle

2.7 Biological Limiting Factors

A number of biological (and behavioural) factors affect leatherback turtles by limiting their potential for population growth.  These limiting factors have been grouped into those observed in the marine environment, and those that exist in the nesting beach habitat.

2.7.1 Marine environment

Leatherbacks depend on prey with very little nutritive content and since this species’ diet of jellyfish is high in water and low in organic content, they must consume large quantities of food (Lutcavage, 1996) to fulfil their food energy requirements.  This is the only known biological limiting factor in Canadian waters.

2.7.2 Nesting beach habitat

Leatherbacks prefer to nest on exposed, open beaches, adjacent to deep water and typically unprotected by fringing reefs.  In some years large numbers of nests on such beaches are lost to flooding and erosion (e.g., Whitmore & Dutton, 1985; Leslie et al., 1996).  In addition, the leatherback turtle is unique in producing numerous yolkless eggs in each clutch for which a selective advantage remains to be identified.  The yolkless eggs may not have a function and thus may be a potential cost to reproduction (Rostal et al., 1996).

Further, Leatherbacks are thought to be a long-lived species but life expectancy is unknown; the age at maturity is estimated at 5-14 years (Zug & Parham, 1996).  This, coupled with a 2-3 year interval between nestings (Hughes, 1996), may limit the ability of populations to rebound in times of low survival rates.