Trade-off between current reproductive effort and delay to next reproduction in the leatherback sea turtle

Abstract

The trade-off between current and future reproduction plays an important role in demographic analyses. This can be revealed by the relationship between the number of years without reproduction and reproductive investment within a reproductive year. However, estimating both the duration between two successive breeding season and reproductive effort is often limited by variable recapture or resighting effort. Moreover, a supplementary difficulty is raised when nonbreeder individuals are not present sampling breeding grounds, and are therefore unobservable. We used capture-recapture (CR) models to investigate intermittent breeding and reproductive effort to test a putative physiological trade-off in a long-lived species with intermittent breeding, the leatherback sea turtle. We used CR data collected on breeding females on Awa:la-Ya:lima:po beach (French Guiana, South America) from 1995 to 2002. By adding specific constraints in multistate (MS) CR models incorporating several nonobservable states, we modelled the breeding cycle in leatherbacks and then estimated the reproductive effort according to the number of years elapsed since the last nesting season. Using this MS CR framework, the mean survival rate was estimated to 0.91 and the average resighting probability to 0.58 (ranged from 0.30 to 0.99). The breeding cycle was found to be limited to 3 years. These results therefore suggested that animals whose observed breeding intervals are greater than 3 years were most likely animals that escaped detection during their previous nesting season(s). CR data collected in 2001 and 2002 allowed us to compare the individual reproductive effort between females that skipped one breeding season and females that skipped two breeding seasons. These inferences led us to conclude that a trade-off between current and future reproduction exists in leatherbacks nesting in French Guiana, likely linked to the resource provisioning required to invest in reproduction.

Kemp's Ridley Sea Turtle Saga and Setback: Novel Analyses of Cumulative Hatchlings Released and Time-Lagged Annual Nests in Tamaulipas, Mexico

“…For example, the annual mortality rate for leatherbacks that nested at Playa Grande, Costa Rica, was estimated to be 34.6% in 199334.6% in -199434.6% in and 34.0% in 199434.6% in -199534.6% in (Spotila et al 2000. In contrast leatherbacks nesting in French Guiana and St. Croix had estimated annual survival rates of 91% (Rivalan et al 2005) and 89% (Dutton et al 2005), respectively. For the St. Croix population, the average annual juvenile survival rate was estimated to be approximately 63%, and the total survival rate from hatchling to first year of reproduction for a female was estimated to be between 0.4 and 2% [assuming age at first reproduction is between 9 and 13 years (Eguchi et al 2006)].…”

Estimating body mass in leatherback turtles Dermochelys coriacea

“…This problem is compounded by the fact that only females are accessible on land and then only for a period of about 24 h in total every 2 to 3 yr while nesting (Girondot & Fretey 1996, Rivalan et al 2005b). Body mass is, however, a key life-history trait and has been reported as the most appropriate parameter for assessing somatic growth, superior to the commonly used measurement of carapace length (Bjorndal & Bolten 1988, Chaloupka & Musick 1997, Price et al 2004).…”

Environmental and anthropogenic impacts on intra-specific variation in leatherback turtles: opportunities for targeted research and conservation

“…Not only has early-stage survivorship been enhanced, but annual adult survivorship appears to be considerably higher for WA leatherbacks (Dutton et al 2005, Rivalan et al 2005) than for EP leatherbacks ), which might also have contributed to the divergence in population trends. Historically unsustainable egg harvest coupled with low adult survivorship (78% yr -1 ) for the Costa Rica population indicates that the chances of population recovery are slim if adult mortality is not decreased (Santidrián Tomillo et al 2008).…”

“…Lewison et al 2004), but bycatch impacts on these populations vary according to spatiotemporal overlap in fisheries operations and critical ontogenetic habitat, as well as according to characteristics of fishing gear (Wallace et al 2008). The observed discrepancy between annual adult mortality rates of WA versus EP leatherback populations (Dutton et al 2005, Rivalan et al 2005) (Table 1) might be due in part to differing degrees of bycatch mortality (Troëng et al 2004). The current Atlantic leatherback bycatch situation consists of industrial longline and trawl fisheries that operate throughout the North Atlantic and incidentally capture several hundred leatherbacks annually, but leatherback mortality in these fisheries is quite low (Watson et al 2005).…”