Agnese Mancini: Project Update: May to June 2008

Sea turtles drowned in gillnets.

Between May and June we focused our attention on a specific site: San Ignacio Lagoon. Located on the on the Pacific coast of the state of Baja California Sur and covering an approximate area of 17,500 ha, the lagoon is located at the southern end of the Vizcaino Biosphere Reserve. It was declared World Heritage site by UNESCO in 1993 and Ramsar site in 2004.The lagoon is a very important feeding and growing site for the East Pacific green turtle (Chelonia mydas). During 2006 and 2007, we recorded a rise in sea turtle strandings possibly related to high bycatch rates. This year we spent more time in the lagoon to observe and document the problem. We counted more than 100 dead turtles both stranded on the beach and floating.

The main cause for this massive mortality event is the incidental fishery in nets used for the guitarfish. Gillnets are thrown in the main channels and checked every 24h. Turtles use the channels to move inside the lagoon and get
usually entangled and die if not freed in the following 1-2h. The problem is that fishermen working inside the lagoon are fishing illegally for two main reasons: they do not have the proper permit to catch guitarfish, furthermore since 2007 Mexican law forbids shark and ray fishery inside bays and lagoons as these areas are used as reproductive and nursery habitat. This fishery usually takes place for 7 to 10 days and at least 10-15 equipments are involved. We estimated that total mortality in june 2008 was around 400 – 600 turtles every year. We invited kids from local communities and worked with them to monitor the beach and spread knowledge about thi situation.