Are sea turtles responsible for lower fish catches in India?
Fishing communities on Agatti Island in Lakshwadeep, India, blame their reduced fish catch on green turtles; according to them, green turtles chomp their way through the seagrass beds lining the shallow reef waters that are essential for fish to breed. This leads some in the community to clandestinely kill sea turtles and destroy their nests.
Wildlife happens to intrude on human "space" mostly while searching for food, and this can result in human deaths, or destruction of human livelihood. The perception of people living close to wildlife in such conflict areas shapes the interaction between them and the wildlife.
Certainly, Agatti's fishing community attributes the drop in fish catch to green turtles, but is this perception accurate? Rohan Arthur and others from the Nature Conservation Foundation, based in Mysore, India, surveyed perceptions of fishers from two places in the Lakshwadeep islands: Agatti and Kadmat. Both are atolls - ring shaped coral reefs with a rim that encircles a lagoon - and both share similar characteristics: size, population, number of households, number and density of fishers, and extent of seagrass meadows. Also, importantly, fish catch had declined in the lagoons of both atolls.
The only difference between the two atolls is the number of resident green turtles. The number of green turtles around Agatti has increased tremendously since the 1970s, due to effective conservation measures in the area. In 2010, the turtle density in Agatti was six to seven times the turtle density in Kadmat (27 turtles per square kilometer of seagrass meadow to 3 turtles respectively).
People's perceptions in both atolls were remarkably different. In Agatti, almost 75% of respondents felt decrease in fish catch was due to green turtles. In Kadmat, less than 20% thought green turtles were responsible. Instead they pointed to a variety of factors, including overfishing.
Fishers in Agatti, however, thought green turtles reduced fish catch in two ways. According to them, green turtles hurt their livelihoods firstly by "direct" damages, such as tearing nets, breaking lines, or driving fish away from nets and thus reducing catch. Secondly, Agatti fishers proposed that turtles at high densities eat up a lot of the seagrasses, reducing habitat available for the fish through "indirect damages." Adult fish from the coral reefs do not like overgrazed meadows, and fewer young fish settle down in them.
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Sea turtle image via Shutterstock.