US and Mexican conservation efforts may have boosted the number of marine turtles visiting UK waters, according to University of Exeter biologists.

New research by the University of Exeter and Marine Environmental Monitoring, published this week in Marine Biology (3 May 2007), analyses 100 years of data. It shows an increase in the number of loggerhead and Kemps ridley turtles in UK and French waters in the last twenty years. The research team believes this is most likely the result of protective measures put in place in the United States and Mexico.

The data tells the story of the interaction between marine turtles and humans over the last hundred years, said Matthew Witt of the University of Exeter. Following a severe decline as a result of human activity in the first-half of the last century, we can now see the positive effect that recent conservation efforts have had on these turtle species.

A large majority of marine turtles that visit Northern European waters hatch in the Americas and can spend nearly four years travelling thousands of miles to British waters. Scientists do not know why some juvenile turtles make the journey to Northern Europe, but believe they may simply be driven by the North Atlantic current system.

The eggs of Kemps ridley turtles were harvested in huge numbers and the species reached near-extinction before protective measures began in the mid-1960s. Previously absent in UK waters since 1974, sightings of this species returned in the 1990s, which coincides with the increasing use of turtle excluder devices in shrimp nets in US and Mexican waters. Both species occurred in western parts of the UK and France, including a number of sightings off the coasts of North-West Scotland, Wales, Devon and Cornwall.

The decline of sea turtles has led to a global protection effort. Measures have included the introduction of turtle excluder devices in fishing nets and hatcheries to protect eggs.