Earthwatch scientist Ricardo Sagarminaga van Buiten, who is studying common dolphin and marine turtles in the Alboran Sea, says, "The longlining season has just begun and we have another period ahead of us that could be disastrous for the endangered loggerhead turtle populations that travel and feed in the south-west Mediterranean. We can expect that around 20,000 will end up getting caught on Spanish fleet longlining hooks alone."
The Alboran Sea has the highest biodiversity within the Mediterranean, but this region also supports large fishing operations which result in thousands of loggerhead deaths each year when the turtles are caught up in fishing lines (known as bycatch).
Van Buiten is calling for tried and tested mitigation measures to be urgently adopted, such as using alternative bait, fishing deeper, using small circular hooks and avoiding turtle hotspots. These measures were tested with the support of NOAA's National Marine Fisheries Service. Van Buiten believes these measures could reduce bycatch rate by more than 85 per cent, and if turtles that are accidently caught by Spanish fishermen are better handled, their chances of survival should also increase.
But Van Buiten fears changes could come too late to save affected turtle populations. "The data coming out of monitoring programmes throughout the Atlantic range - where these turtles nest - are not very promising, with major nesting populations dropping at a fast rate."
Urgent action is all the more crucial in the light of his latest research findings.* Van Buiten and colleagues from WIDECAST (the Wider Caribbean Sea Turtle Conservation Network) have become the first to document real-time migrations of loggerhead turtle from the Mediterranean across the Atlantic Ocean. Using satellite transmitters, they tagged three loggerhead turtles.
"At least one, and possibly two of the three turtles that left the Mediterranean went to the Caribbean, indicating the possible importance of the Mediterranean Sea to western Atlantic nesting stocks south of the US," said Van Buiten.
To gain the support of researchers and conservation organisations worldwide, Van Buiten is planning an international workshop during the Aguaviva Festival in June in the Canary Islands. The outcome of the International Cooperation for Mitigating Bycatch in Surface Long Lining workshop will be included in a report, Adaptive Management Scheme for Spanish Mediterranean Longlining Fisheries, which will be presented to the Spanish Fishery Department (SGM) by the end of the year.
Since 1999, Earthwatch volunteer teams led by Van Buiten and Dr. Ana Canadas have been working on board a 20-metre wooden vessel in the Alboran Sea to monitor marine species.
*The latest research findings are published in a report, Modeling Loggerhead Turtle Movement in the Mediterranean: Importance of Body Size and Oceanography, produced by Ricardo Sagarminaga van Buiten of Alnitak (on behalf of the Spanish Cetacean Society), Scott Eckert, Karen Eckert and Daniel Dunn of the Wider Caribbean Sea Turtle Conservation Network, Jeffrey Moore and Patrick Halpin of Duke Center for Marine Conservation.
Scientists from Earthwatch fear the longline fishing season will have a devastating impact on endangered loggerhead turtles in the Mediterranean Sea.