How reliable are turtles for measuring ocean trash and marine health?

When a sea turtle turns up dead on the beach, it often makes the news, especially if the death appears to result from plastic debris in the turtle’s stomach. Scientists and the public in general are concerned about the increase in ocean trash and the effects of plastics on marine life. Many view the news reports as scientific updates and assume turtles are like canaries in coal mines when it comes to monitoring the health of the ocean and marine life.