The decline in various sea turtle populations is largely attributed to overharvesting for meat, eggs, leather and shell (King, 1982; Ross, 1982). Additional loss of late juvenile to adult life stages occurs when turtles are taken as incidental catches during shrimp trawling (Hillestad et al., 1982), at industrial water intakes (pers. obs.) or are killed in areas where undersea explosives are used (Klima, unpubl.). Late juvenile and sub-adult losses are particularly important because turtles entering their breeding years represent several decades of selective survival and are the groups whose survival is most likely to influence the long-term stability of the population (Crouse et al., 1987).
Protective measures against the incidental take of sea turtles have been developed. For example, turtle exclusion devices (TEDS) let captured turtles escape from shrimp trawls, considerably reducing incidences of turtle drownings (Watson et al., 1986). Physical barriers can be effective in specific situations, but development of a method to exploit a turtle's avoidance response would be useful in many industrial applications.