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The value of long-term monitoring of marine turtle nesting

 

For nearly 20 years, we’ve been working closely with local communities in Lamu seascape to monitor and safeguard key marine turtle nesting sites.

Community-based patrols have enabled us to collect a wealth of information about the turtles that come to nest on our beaches. Earlier this month, we shared that information with the wider scientific community through the publication of a scientific paper.

In 1997, we initiated a community-based marine turtle monitoring and conservation programme in Lamu seascape in partnership with the Kenya Wildlife Service and local communities. Since it began, the key activities of this programme have included the monitoring of nesting activity and strandings on key beaches, relocation of nests that were established in unsuitable or risky locations and flipper tagging (which is now supplemented by satellite tagging).

Turtle hatchling in Lamu © Jonathan Caramanus/Green Renaissance/WWF-UKTurtle hatchling in Lamu © Jonathan Caramanus/Green Renaissance/WWF-UK

Long-term monitoring is crucial to provide insights into marine turtle population dynamics and to evaluate the effectiveness of conservation activities. Involving the local community in this is essential to draw on their expertise, to ensure that monitoring is feasible and low-cost, and to help build knowledge and awareness to strengthen the role of local communities as champions of turtle conservation.

The challenges facing marine turtles underscore the need for community involvement in their conservation. Accidental bycatch, for example, is a really big problem. So too is poorly planned developments in key turtle habitats and the associated pollution that can often ensue. Marine turtles are also threatened by illegal trade in their shell, meat and eggs.  What’s been really great to see however is the diversity of local community members that have got involved in conservation efforts – we have young and old, male and female, groups and individuals all coming together to help secure a future for these incredible marine creatures in the Lamu seascape.

The data that has been collected collaboratively with the local community is, we believe, the first published assessment of long-term spatial and temporal trends in sea turtle nesting activity along the East African coast. That gives you an idea of just how important this data is!

Recording turtle nests © Jonathan Caramanus/Green Renaissance/WWF-UKRecording turtle nests © Jonathan Caramanus/Green Renaissance/WWF-UK

Over the 17 year study period, a total of 2,021 nests were reported. We don’t necessarily monitor all the turtles that come to nest in Lamu seascape – especially when security issues limit our ability to travel around – but this figure gives you a good indication of the sort of numbers we’re dealing with. Of those nests, 97.5% were green turtle nests, 1.5% were hawksbill nests, 0.4% were olive ridley nests, and 0.5% of nests were from unidentified marine turtle species.

From those nests, 214,926 eggs were recorded and 173,333 (81%) were successful hatchlings.  Those numbers might sound big but, as I’ve written about in previous blogs, life as a marine turtle is tough and it’s estimated that only about 1 in 1,000 hatchlings will survive to adulthood. Incubation period for green turtle eggs ranged from 40 to 67 days, for hawksbill eggs from 49 to 60 days, and for olive ridley eggs it ranged from 50 to 60 days.

The data showed that nesting activity occurs year round, but 74% of nests were recorded between March and July, with the highest number (21%) recorded in May – which is always a busy month for us! For green turtles, where we had lots of data to test, nesting peaks during the wet season months, and was strongly linked to mean monthly rainfall and sea surface temperature. The data also showed that seasonality also had a strong influence on hatching success. A lower success rate was seen was dry north-east monsoon season, when elevated nest temperatures are likely to occur

We’re really proud that the data we’re collecting is helping global efforts to better understand the biology of marine turtles. I can’t wait to show the local community our scientific paper in print – it will inspire all of us!

Mike Olendo and volunteers © Jonathan Caramanus/Green Renaissance/WWF-UKMike Olendo and volunteers © Jonathan Caramanus/Green Renaissance/WWF-UK

WWF’s Coastal Kenya Programme is gratefully supported by players of People’s Postcode Lottery and Size of Wales.

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