One of the threats to endangered sea turtle species is the use of nets by commercial shrimp-fishing boats. When turtles get accidentally caught in the nets, they cannot rise to the surface of the ocean to breathe, and they die. Some people suggest that this problem can be solved through an invention called a turtle excluder device (TED) that is incorporated into the nets. A TED provides a passage through which the turtles can escape. However, TEDs have been criticized for several reasons.
First, some shrimpers (shrimp fishers) argue that turtles get trapped only rarely: it is estimated that on average, one shrimp boat accidentally catches about one turtle every month. On the other hand, using TEDs costs the shrimpers some of their catch. Every time the shrimpers cast the nets, a certain percentage of shrimp manage to escape through the turtle passages. The shrimpers complain that the cost of losing shrimp on a daily basis is too high in comparison with the small chance of saving one turtle.
Second, there are alternative methods of protecting sea turtles that may be more effective than TEDs. One method that can be used is shortening the time limit that shrimp boats are allowed to keep their nets underwater. When the time limit is reached, the nets have to be pulled up to the surface, allowing any turtles caught in the net to get air and also giving shrimpers the opportunity to release the turtles from the nets.
Third, TEDs are not effective for larger species of endangered sea turtles. Some species like loggerhead and leatherback turtles can grow to be quite large and cannot fit through the escape passage that standard TEDs provide. Such turtles cannot escape from the nets even if the nets are equipped with TEDs.
Many experts believe that turtle excluder devices, also known as TEDs, are a very good way to protect endangered turtles, and that they should be a vital part of the equipment on any shrimp boat. Here are their responses to the criticisms that you just read about.
First, it’s true that catching a turtle is a rare thing for any one boat. However, there are, for example, thousands of shrimp boats operating off the southern coast of the United States. Collectively these shrimpers accidentally catch thousands of turtles every year. And these are endangered sea turtles whose populations are already too small, so harming several thousand every year is a big problem. So when considering the impact of TEDs, don’t think in terms of an individual shrimper losing a few shrimp, but rather in terms of how the sea turtle population as a whole is affected by the shrimp industry as a whole.
Second, implementing time limits to ensure that the turtles are brought up for air in time—that sounds like a good idea, but only in theory. The problem is that the time limits are almost impossible to enforce. There’re thousands of shrimp boats far out at sea, and government patrol boats cannot really monitor the time limits all these boats use. The use of TEDs is easier to enforce: all that’s required is checking the shrimp boats before they leave port and making sure their nets have TEDs.
Third, it’s true that TEDs can be too small for some very large species of turtle. But in the areas where they’re needed, it’s not a problem to create TEDs that are somewhat larger. The design of the TED can be modified easily without affecting the way that it functions. So once larger TEDs begin to be produced, this will no longer be a problem.