The data received from the satellite tags can involve several challenges, such as
determining the precise locations of turtles. Accuracy in calculating the most likely
position increases as the number of signals received increases. Other challenges
involve loss of battery power, damage to the antenna, epibionts on transmitters and
antennae, and so on. ARGOS is not a simple system, but it offers a large amount of
high-quality information.
The LIFE/NAT/E/8610 Project (2002-2006), in which the IEO participated,
tagged 21 loggerhead turtles with satellite transmitters (Eckert et al. 2008). The
results obtained indicated movements from the Alboran Sea and the coast of Murcia
to the central Mediterranean, as well as the migration of specimens towards the
Atlantic that reached the Caribbean coasts. The recapture on the coast of Spain of a
loggerhead tagged with a conventional metal tag in the western Atlantic (Moncada
et al. 2010) is evidence of western and eastern loggerheads forming part of the same
population (i.e. in the current western Atlantic RMU; Wallace et al. 2010) as well as
evidence of the transatlantic journey made by many loggerheads to feed in Mediterranean habitats.
In 2008, of the scientific papers on sea turtle satellite tracking worldwide, 11%
referred to transmitter deployment in the Mediterranean (Godley et al. 2008). In
2014, a study analysed 195 routes of satellite-tracked turtles published in peerreviewed articles (Luschi and Casale 2014). Only one study has described telemetry
experiments in the Alboran Sea (Eckert et al. 2008). In this study, 19 loggerheads
were captured by hand off the Spanish coast and fitted with transmitters. Three
subadult loggerhead sea turtles were monitored for up to 363 days as they moved
west across the Atlantic Ocean. Large individuals (CCL <57 cm) gradually moved
eastward through the Mediterranean Sea after release. Only 14 green turtles have
been satellite tracked in the Mediterranean Sea, all of which were in the eastern part
of the area. To date, no leatherbacks have been monitored.
The main reason for the limited number of such studies is that sea turtles are
typically equipped with satellite tags when they lay their eggs on beaches; however,
there are no nesting areas in the Alboran Sea (Laurent et al. 1998). The second reason
is that the loggerheads observed in this area are generally too small to be equipped
with the satellite tags that are currently available on the market. Loggerheads are the
most common sea turtle species in the Mediterranean.
Nevertheless, this situation could change because there have been recent reports
of new nesting events in the western Mediterranean Sea, which may be due to a
change in sea temperatures (Maffucci et al. 2016). There is a real need to understand
the potential impact of climate change in the Alboran Sea, and telemetry could be the
appropriate tool to achieve this aim.
21.6.3 Seabird Tagging Studies
Hundreds of thousands of birds are known to migrate between the Mediterranean
and the Atlantic above the sea pass through the Strait of Gibraltar (Halpin et al.
732
J. C. Báez et al.
determining the precise locations of turtles. Accuracy in calculating the most likely
position increases as the number of signals received increases. Other challenges
involve loss of battery power, damage to the antenna, epibionts on transmitters and
antennae, and so on. ARGOS is not a simple system, but it offers a large amount of
high-quality information.
The LIFE/NAT/E/8610 Project (2002-2006), in which the IEO participated,
tagged 21 loggerhead turtles with satellite transmitters (Eckert et al. 2008). The
results obtained indicated movements from the Alboran Sea and the coast of Murcia
to the central Mediterranean, as well as the migration of specimens towards the
Atlantic that reached the Caribbean coasts. The recapture on the coast of Spain of a
loggerhead tagged with a conventional metal tag in the western Atlantic (Moncada
et al. 2010) is evidence of western and eastern loggerheads forming part of the same
population (i.e. in the current western Atlantic RMU; Wallace et al. 2010) as well as
evidence of the transatlantic journey made by many loggerheads to feed in Mediterranean habitats.
In 2008, of the scientific papers on sea turtle satellite tracking worldwide, 11%
referred to transmitter deployment in the Mediterranean (Godley et al. 2008). In
2014, a study analysed 195 routes of satellite-tracked turtles published in peerreviewed articles (Luschi and Casale 2014). Only one study has described telemetry
experiments in the Alboran Sea (Eckert et al. 2008). In this study, 19 loggerheads
were captured by hand off the Spanish coast and fitted with transmitters. Three
subadult loggerhead sea turtles were monitored for up to 363 days as they moved
west across the Atlantic Ocean. Large individuals (CCL <57 cm) gradually moved
eastward through the Mediterranean Sea after release. Only 14 green turtles have
been satellite tracked in the Mediterranean Sea, all of which were in the eastern part
of the area. To date, no leatherbacks have been monitored.
The main reason for the limited number of such studies is that sea turtles are
typically equipped with satellite tags when they lay their eggs on beaches; however,
there are no nesting areas in the Alboran Sea (Laurent et al. 1998). The second reason
is that the loggerheads observed in this area are generally too small to be equipped
with the satellite tags that are currently available on the market. Loggerheads are the
most common sea turtle species in the Mediterranean.
Nevertheless, this situation could change because there have been recent reports
of new nesting events in the western Mediterranean Sea, which may be due to a
change in sea temperatures (Maffucci et al. 2016). There is a real need to understand
the potential impact of climate change in the Alboran Sea, and telemetry could be the
appropriate tool to achieve this aim.
21.6.3 Seabird Tagging Studies
Hundreds of thousands of birds are known to migrate between the Mediterranean
and the Atlantic above the sea pass through the Strait of Gibraltar (Halpin et al.
732
J. C. Báez et al.