Ex-situ marine turtles conservation strategies: loggerhead reintroduction program in Canary Islands

Abstract

All along the eastern Atlantic Ocean there is only one loggerhead (Caretta caretta) breeding colony, housed in the Cape Verde archipelago. There are evidences of sporadic nesting activities of the specie in the African coast, but no accurate data. Cape Verde beaches harbors the third largest loggerhead nesting population in the world, and the second one of the Atlantic, after the eastern U.S. colonies. The most important area all around the Archipelago is the Protected area “Reserva Natural das Tartarugas (RNT)”, southeastern Boa Vista Island, which houses the 80% of Cape Verde loggerhead nests. This high density of nests in such a small stretch of beaches (RNT, 20km of beaches) turns it in a very vulnerable colony whose conservation and protection are crucial for the specie. Two NGOs (Cabo Verde Natura 2000 and ADS- Biodiversidad) have been carrying out conservation and protection activities since 1998 in the area, but increasing the number of loggerhead breeding colonies in eastern Atlantic could give an important step in the global conservations efforts on loggerhead turtle. Cape Verde and Canary Islands are oceanic archipelagos of the Macaronesian region, which share several characteristics: volcanic origins, climate and oceanographic conditions, flora and fauna endemism etc. Cape Verde has the only loggerhead nesting colony in the area, and Canary Island has evidences of marine turtle nesting activities in their oriental islands in the past. The similarities between both archipelagos, the evidence of marine turtle nesting activity in the Canary Islands, and the dangerous conservation status of the marine turtles around the world, had resulted in the development of a huge Experimental and Conservation Program to re-establish the loggerhead nesting colony in the oriental islands of Canary Islands. This Reintroduction Program is based on three key goals: 1. Support conservation and protection ac- tivities on the origin population: the Capeverdian breeding colony; 2. Research in long-distance egg translocation and incubation experiments; 3. Head-starting programs to increase survival rates and de- crease the number of eggs removed from the origin population (Cape Verde). In 2006, a viability study started with a low number of eggs (3 nests) collected from Boa Vista Island, Cape Verde, to experiment the incubation conditions of the Canarian beaches (Cofete beach, Fuerteventura). Also laboratory experiments (200 eggs) were carried out. The 85.4% of the eggs disposed in the canarian beaches hatched successfully and the hatchlings showed very good conditions. From 2007 to 2010, 800 - 1000 eggs per year (8-14 nests) were removed from the Cape Verde beaches to the Canary Island (200 eggs/year to laboratory experiments, and 500-800 eggs/year to beach incubation). Canarian beaches showed good incubation conditions to loggerhead eggs (hatching success ranged from 65.3% to 86.6%). Head-starting programs were carried out with all neonates hatched in Canary Islands, and they have been a very important tool to study the little-known first years of life of these animals.