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Tagging turtles in the Canary Islands.

Soledad Esnaola - October 2005

Our catamaran, the Oceana ranger, has started its well-earned break so it can be reconditioned after 11 months spent sailing across the oceans of the world. This time, our campaign has had a change of scene and back-up; we're heading towards the Canary Islands - the most south-westerly territory in Spain, some 1,400 kilometres to the south of the Iberian peninsula - to work in collaboration with SECAC (Spanish Society for the Study of Cetaceans in the Canary Archipelago). Oceana and SECAC are participating jointly in this project which has two objectives:

to affix satellite transmitters to 10 loggerhead turtles (Caretta caretta); and
to monitor and observe them and obtain biological and behavioural information on the numerous species of cetaceans in the waters of the Canary Islands.

To do so, during the 15 days of the campaign, their positions, behaviour and the number of individuals observed were recorded; tissue samples were taken (biopsies) from dolphins and whales; and, without much success, we tried to affix electronic tags to some of the cetaceans.

Our little expedition started on 10 October. After preparing all the necessary material in Madrid, María Hernández, our expert turtle-tagger, and I set off for the island of Lanzarote, where Charlotte Hudson (Oceana's Senior Marine Wildlife Scientist in Washington DC, USA) was waiting for us and Catherine McClellan (research scientist at Duke University, USA, and expert in tagging turtles), who were to coordinate tagging operations.

Once at the SECAC base, we met Videl Martín (Director of the Spanish Cetacean Society and a well-known scientist in the field of cetaceans) and our companions for the next 15 days on board the Oso Ondo, a motor-boat of around 17 metres skippered by Arquímedes ("Quilme" to his friends). Vidal was in charge of coordinating and organising the expedition, which was tremendously useful thanks to his years of experience and intimate knowledge of the marine fauna in the waters of the Canary Archipelago.

Once on the boat had been kitted out and provisioned, we set sail from the port of Arrecife (Lanzarote) towards the coasts of Fuerteventura and Gran Canaria, leaving behind us the tuna seiners coming back from fishing and sailing across waters that reach depths of up to 2,000 metres just a few miles off the coast and separate the seven islands of the volcanic archipelago. The little lounge of the Oso Ondo became filled with laptops, cameras and papers as we got down to work.

There were seven of us on board (all women) plus Vidal and Quilme, who were excused from sighting shifts in exchange for 24-hour service coordinating and skippering respectively. The day of patrolling the seas lasted for 10 to 12 hours, during which we rotated two-hour sighting shifts, in pairs, from the top of the boat, noting our position with GPS. The hours pass very slowly when you don't see anyting and you've been sitting in the sun for two hours, but as soon as a whale blow or fin was spotted a huge shout went up: SIGHTING!!! and Antonella and Vidal would grab their cameras, Silvia her curette for the biopsies, Cristina her video camera and everyone else ran to note the position and behaviour of the animals and continue the watch so as not to lose the group. No caffeine ever woke anuone up as quickly as that shout!

Every dya we saw at least two groups of cetaceans, the most common sightings being Atlantic spotted dolphins (Stenella frontalis) and bottlenose dolphins (Tursiops truncatus). However, it was not quite so easy to spot turtles. The ideal conditions for sighting turtles are a clear day and completely calm sea, like a mill pond, which in October is not a common as in the tranquil summer months. Fortunately, and thanks to Vidal and the Tarifa Rehabilitation Centre for Wild Animals (Gran canaria), headed by biologists and veterinarian Pascual Calabuig, we managed to get hold of five loggerhead turtles that his centre had rescued onto which we could affis the satellite tags. We managed to catch another three turtles from the Oso Ondo and release them to the sea again once they had been tagged, trying to cause the minimum stress. Once we had the turtle on board, a series of data and biological samples were taken: size (width, length, shell), weight, and blood, skin and shell samples, which were kept and stored for subsequent laboratory analysis. The process of affixing the satellite transmitter is not an aggressive one, but it is slow and painstaking work. The shell needs to be cleaned well and a transparent epoxy resin applied with which the tag is affixed, which takes a few hours to dry. The turtle were monitored constantly and checked to make sure they didn't try to remove the transmitter, because when the epoxy is still wet it can stain the animal's skin.

As soon as the tag was affixed and ready, we stopped the engines and returned the turtle to the sea, which was as happy to be back there as we to be able to return it to its environment.

Finally, having sailed for many miles around the coasts of Gran canaria, Fuerteventura and Lanzarote, I think the campaign was a success. We managed to successfully tag eight turtles of the 10 we were aiming for initially (this is a good pass rate!), which was no easy task at this time of the year; we sighted nine different species of cetaceans including Atlantic spotted dolphins (Stenella frontalis), some very shy beaked whales, a fin whale (Balaenoptera physalus), Risso's dolphins (Grampus griseus), short-finned pilot whales (Globicephala macrorhynchus) and, of course, sperm whales (Physeter macrocephalus) from which numerous tissues samples were taken and on which we almost managed to affix an electronic tag.

It is a pleasure to work with professionals who enjoy their work and to see that thing well done...come out well. Almost everyting on the campaign was a great experience (even the early starts and 12 hours in the sun!), but if I were to pinpoint one thing during the trip, I would actually choose two: the baby sperm whale that frolicked for a few minutes alongside the prow of the boat, and Quilme's stories from his fourteen years of fishing on the tuna seiners.