Ten percent of soil in the United States is protected land for wildlife, but only one percent of ocean waters keep marine animals safe from fishermen. A new study led by Graeme Hays of Deakin University has indicated that these protected areas aren’t nearly large enough to protect sea turtles during their extensive migrations, which tracking devices proved to be much longer than previously believed. The study’s findings were published in the journal Conservation Biology.
Marine Protected Areas (MPAs) are a relatively new concept that encompass seven levels of wildlife protection. For this study, the researchers tagged eight sea turtles within the 640,000 square kilometer Chagos Archipelago MPA in the Indian Ocean, one of the largest in the world. The turtles were tracked via satellite throughout their migration.
"Over the last few years, governments around the world have declared some massive marine parks, typically around ocean islands,'' Hays said in a press release. "How well these protect marine life has been heavily debated.”
The data revealed that for these sea turtles, the MPA didn’t do much to protect them at all during migration. Out of the eight, only one stayed within the protected area. All of the others ventured more than 1000 kilometers away from safety, with one turtle breaking a migratory record by swimming an astonishing 3979 kilometers away.
Of course, that’s not to say that MPAs don’t do anything. For organisms like coral and non-migratory fish, having a protected area does make a considerable difference. Migratory animals like sea turtles, whales, seals, and sharks just cannot stay within the confines of a small protected area all of the time. However, the MPAs do protect animals who use the area for a breeding ground and are more vulnerable to exploitation.
"This massive MPA is of value for green turtles, particularly as it protects them throughout the breeding season. But our work shows that even massive MPAs need to be supplemented with networks of smaller protected areas,” Hays continued.
These green sea turtles are primarily found in tropical and subtropical waters of the Atlantic and Pacific Oceans. Over the last three generations, there has been a roughly 55% decline in the number of females nesting which has led to them being categorized as endangered. These turtles take the longest out of any sea turtle population to become reproductively mature at around 26 years. These long generational times make it difficult for numbers to rebound.
The biggest human threat to these turtles is harvesting the eggs, because some countries believe them to be an aphrodisiac. MPAs would protect the turtles in this case, though they have not been set up in every breeding zone. Outside of the MPA, turtles risk being harmed by humans accidentally, via habitat destruction, entanglement in nets, or as bycatch by fishermen.
The researchers hope that this study will impact placement of future MPAs to protect green sea turtles throughout their extensive migratory journey.