High mortality of Olive Ridley turtles (Lepidochelys olivacea) in ghost nets in the central Indian Ocean

Lost, abandoned or discarded fishing nets, otherwise known as ‘ghost nets’, pose a serious risk to large marine fauna throughout the world, including in the Indian Ocean. Since 1988, a total of 129 Olive Ridley Turtles (Lepidochelys olivacea) have been found entangled in ghost nets in Maldivian waters. Given that the predominant fishing techniques used in the Maldives are pole-and-line and handline, the majority of ghost nets found must have drifted with oceanic currents from neighbouring countries and international waters. Our data suggest that these nets may be coming to the Maldivian waters from India, Sri Lanka, and further afield in Southeast Asia during the Northeast Monsoon, and from the Arabian Sea during the Southwest Monsoon. Entangled Olive Ridley Turtles are most often encountered in the Northeast Monsoon, and sexually immature individuals make up the majority of entanglements. 71% of Olive Ridley entanglements were associated with large conglomerates of multiple fishing nets. Individual net samples had stretched mesh sizes ranging from 35mm to 590mm and were of knotted multifilament construction. A challenge continues to be identifying from which countries, and which fisheries, specific nets are originating. In this report we examine 74 separate ghost net conglomerates recorded from the Maldives, Sri Lanka, and India between July 2013 and July 2014. Our findings suggest that some of the nets originated from India and Thailand, while others are pieces of fish aggregating devices (FADs) from the western Indian Ocean. We also report on the risk that these nets pose to the populations of the Vulnerable Olive Ridley Turtle in the Indian Ocean. We recommend a reduction in gillnet fishing capacity in the region; improved net disposal facilities in ports; a system of no‐blame gear loss reporting; a centralised database of Indian Ocean fishing net construction parameters; and the rapid adoption of non-entangling FADs by all fleets.