Saving Sea Turtles
Conservation of sea turtles is clearly no easy feat. Their reliance on diverse habitats, ranging from unsullied and open access tropical beaches, to offshore nursery grounds, to unrestricted migration corridors across whole ocean basins, to productive feeding grounds on coral reefs, seagrass meadows, and cold open ocean areas, means that cooperation among countries is essential.
Marine and coastal protected areas are an indisputably important tool in the sea turtle conservation toolkit. But these protected areas must be strategically linked throughout the chain – weak protections at any of the necessary habitats can undermine even the strongest conservation efforts at the nesting beach or in coastal habitats frequented by adults. High seas protected areas are needed, even though these are difficult to establish and even more difficult to enforce2. Pelagic protected areas will have to address fishing, shipping, and even contamination by debris – plastic bags, balloons, polypropalene pellets, and other trash constitute an insidious threat to all turtle species. And even protected beaches are difficult to maintain in a way suitable for maintaining or recovering sea turtle populations: introduced species such as dogs, cats, pigs, goats, raccoons, mongoose, etc. are difficult to eradicate from the beach, and there is only so much manpower available to guard nesting females and clutches of eggs through their two month long incubation periods.
While important nesting beaches can be and often are protected as parks or reserves, in many cases the very existence of the beach is at risk from human activities, sometimes far from the coast. With worldwide use of freshwater for irrigation, consumption, and hydroelectric power, estuaries around the world are showing signs of massive sediment starvation (decreases of freshwater limiting the delivery of sediment to the coast)3. This affects the maintenance of shorelines and some beaches. Others are formed by sands produced through a combination of coralline animal and coralline algae remains. When coastal development or blast fishing destroys part of the reef system, beach formation can cease and beaches erode away. And increasingly frequent tropical storms and the occasional tsunami can instantly erase nesting beaches from the face of the earth.
Perhaps even more important than habitat protections are international agreements, regulations, and enforcement of laws concerning commercial fishing in areas frequented by turtles – either those resident or those migrating through. Longline fisheries have decimated leatherback turtle populations, especially in the eastern Pacifici4. Gillnets are devastating to all marine turtle species. And bottom trawls routinely drown loggerhead, ridley, and other species – since sea turtles commonly feed on the very things we wish to catch, such as shrimp or prawns. Since so many sea turtles are killed incidentally in commercial fishing operations, their protection means restructuring how and where we fish -- something that is notoriously difficult to do when highly lucrative fishing interests are at stake.
And we cannot forget that on the other end of the economic spectrum, sea turtle eggs and adults represent an important source of protein to impoverished and marginalized people the world over, who continue to harvest adult turtle products even when the practice is illegal, because of lack of economic or subsistence alternatives. For such people the choice is considered one between “us and them”, and conservation commonly takes a back seat to human survival.
This is not to say that marine turtle conservation has not made great headway in the last 50 years. Some populations of sea turtles are stable or recovering, thanks to intensive efforts to protect nesting beaches, equip the most damaging fishing gears with Turtle Excluder Devices (TEDs), establish voluntary ordinances to shield nesting beaches from artificial light, and create strict regulations on take (as exists, at least on paper, in most coastal countries in the world). And there are innovative approaches being adopted as well. In the U.S., temporary closures are instituted in the mid-Atlantic when northwardly migrating leatherback turtle numbers reach a critical threshold. In the Pacific, many fishing fleets have instituted the use of circle hooks on longlines, to reduce turtle by-catch, and that of other highly valued but not targeted species5.
However, for every step forward we seem to falter, and even take some steps back. The Pacific populations of the leatherback turtle are plummeting so drastically that some predict their imminent extirpation6. The Kemp's ridley is barely holding on despite many decades of head-starting and a strong focus on getting all shrimp trawlers in the Gulf of Mexico where they occur equipped with TEDs. And many coastal species, such as loggerheads and green turtles, show signs of disease, such as extensive fibropapillomas. Fibropapillomatosis has been called the most important health problem affecting sea turtles in the wild7. There seems to be a clear link between water quality and the etiology of this disease, such that outbreaks are occurring in more and more new places as coastal habitats become increasingly degraded.
There are also bigger forces at play. Climate change threatens to send some species over the brink, not only by affecting habitat or food availability, but also because higher than normal sand temperatures at nesting beaches will produce only one gender of hatchling (usually all males).
Thus, despite turtles having touched so many humans, we seem somehow incapable of securing their futures alongside our own. As a metaphor, then, the continued decline of something so thoroughly cherished around the world is a sobering one indeed.
Endnotes
1 People wishing to get more detailed information about the extant sea turtle species should visit the following websites: www.seaturtlestatus.org and www.seaturtle.org. A compendium of scientific descriptions of natural history, behavior, and conservation is available in K. Bjorndal [ed.] 1995. Biology and Conservation of Sea Turtles. Smithsonian Institution Press, Washington DC. The late Archie Carr wrote many popular accounts of sea turtles, including his famous So Excellent a Fishe. 1967. Charles Scribner and Sons, NY; decades later Jack Rudloe wrote Time of the Turtle. 1979. E.P. Dutton, NY. Most recently, O.G. Davidson wrote Fire in the Turtle House: the Green Turtle and the Fate of the Ocean. Perseus Books Group, Cambridge, MA. There have been hundreds of other publications about sea turtles in the past decades.
2 See D. Hyrenbach, K. Forney and P. Dayton. 2000.Marine protected areas and ocean basin management. Aquatic Conservation: Marine and Freshwater Ecosystems 10:437-458.
3 Millennium Ecosystem Assessment. 2005. Vol. 1 Current State and Trends. Island Press, Washington DC
4 Spotila et al. 1996. Worldwide population decline of Dermochelys coriacea: are leatherbacks going extinct? Chelonian Conservation Biology 2:209-222.
5 See for example Watson, J.W. and D.W. Kerstetter. 2006. Pelagic longline fishing gear: A brief history and review of research efforts to improve selectivity. Marine Technology Society Journal 40:6-11.
6 Spotila, J.R., R.D. Reina, A.C. Steyermark, P.T. Plotkin and F.V. Paladino. 2000. Pacific leatherbacks face extinction. Nature 405:529-530.
7 Herbst 1994 and George 1997, cited in Formina, A. et al.. 2007. Fibropapillomatosis confirmed in Chelonia mydas in the Gulf of Guinea, West Africa. Marine Turtles Newsletter 116:20-22
All photos by T. Agardy unless otherwise credited |
