Home > Guardians in action
©Madeira Whale Museum
Bottlenose dolphin Tursiops truncatus
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European Eel Anguilla anguilla
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Loggerhead Sea Turtle Caretta caretta
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Cory’s Shearwater Calonectris diomedea
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The dolphin that everyone knows!
The bottlenose dolphin is the best known of all cetaceans. It figured in the legends of ancient Greeks and Romans in the past and, is a well-known star of movies and television shows, (Perrin et al, 2009, Mead et al, 2002).
In the wild, some individuals have developed social interactions with humans, such as cooperating with fishermen in the capture of prey (Perrin et al, 2009).
Distribution
This species inhabits most warm temperate and tropical shorelines, adapting to a variety of marine and estuarine habitats, even ranging into rivers. They are primarily coastal but are also found in pelagic waters, near oceanic islands, and over the continental shelf (Perrin et al, 2009).
There appear to be two main varieties of this species: a smaller, inshore form, and an oceanic one, larger and more robust that lives mainly offshore (Shirihai and Jarret, 2006, Carwardine, 2002).
Ecology
Bottlenose dolphins have very fluid social groups. In their fission–fusion society, group composition changes very quickly. However, some long-term relationships have been documented with individuals sighted together for years at a time. They are typically found in groups of 2–15 individuals, although groups of more than 1000 have been reported (Perrin et al, 2009).
Threats
Threats of human origin include entanglement in nets, entanglement in or ingestion of recreational fishing gear, pollution, boat collisions, noise, tourism and direct hunt (Perrin et al, 2009).
Conservation
Although there are many threats operating on local populations, bottlenose dolphins are widespread and abundant, and as a species it does not appear to merit concern for major global population decline (Perrin et al, 2009).
The species is listed in Annex II of Habitats Directive (Natura 2000 network) and Appendix II of CITES. EU governments, throughout the Habitats Directive, are required to consider the areas where this species occurs for the establishment of Special Areas of Conservation (SACs; Cañadas 2006; Wilson et al. 1997).
Interesting facts
- Bottlenose dolphins can reach 4.1 meters in length and weight 650kg (Shirihai and Jarret, 2006).
- Female common bottlenose dolphins can live to more than 57 years, and males up to 48 years (Perrin et al, 2009).
- They produce a large variety of whistles, including “signature whistles” that are individually specific and appear to be used to communicate identity, location, and possibly emotional state (Perrin et al, 2009).
- Bottlenose dolphins are one of the few species, besides humans, that can recognize themselves in mirrors (Perrin et al, 2009).
References
Perrin, W. F., Würsig, B., Thewissen, J.G.M. (Eds.), 2009. Encyclopaedia of marine mammals, second ed. Academic Press, Amsterdam, 1316pps.
Shirihai, H., Jarret, B., 2006. Whales, Dolphins and Seals – A Field Guide to the Marine Mammals of the World, A&C Black, London, 384pps.
Cañadas, A. (2006). Towards the conservation of dolphins in the Alborán Sea. PhD thesis, University Autónoma de Madrid.
Wilson B, Thompson P. M., Hammond, PS (1997) Habitat use by bottlenose dolphins: seasonal distribution and stratified movement patterns in the Moray Firth, Scotland. Journal of Applied Ecology, 34: 1365-1374.
Mead, J. G., Gold, J. P., 2002. Whales and Dolphins in Question, The Smithsonian Answer Book, Smithsonian Institution Press, Washington and London, 200pps.
Carwardine, M., 2002. Whales, Dolphins and Porpoises, Dorling Kindersley Publishing, London, 255pps.

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Alberto Molina Serrano Volunteer for ANSE
How did you get involved?
Although I had heard about ANSE, I did not start to collaborate with them until I made a course of identification of cetacean and seabirds. Since then, I have participated in three different campaigns with dolphins. Recently I’ve started to help with birds ringing as well. |
The mystery of the eel
For centuries, scientists have wondered where the European eel reproduced. Different theories have existed since the time of the Romans and the Greeks. Aristotle believed that eels belonged to the worm family and that they would reproduce spontaneously, in the soil. It was not until the late 18th century when eels were accepted as a type of fish. The exact location where they spawn is still a mystery.
Distribution
European eels are widely distributed within European freshwaters. From North Cape in Norway, southwards along the Atlantic coast of Europe, all coasts of the Mediterranean including the North African Coast. Small populations also exist in the White and Barents Sea and eastward to the Pechora River in northwest Russia.
Lifecycle
The European Eel is the only European fish that is catadromous, meaning that it spawns in the sea having spent most of its life in freshwater. It has a complex lifecycle which involves travelling 10,000km - from spawning grounds in the Sargasso Sea across the Atlantic Ocean to the rivers and lakes of Europe, where the eels grow and develop for up to 30 years before travelling back to the Sargasso Sea to spawn the next generation.
Threats
The European eel has seen a decline in recruitment into European Rivers of up to 90% since the 1980s and is now registered on the IUCN Red List as Critically Endangered. Threats are suggested as being a combination of habitat loss, barriers to migration, parasites, pollution, over-fishing and climate change affecting oceanic currents.
What conservation solutions have been put in place?
The European Union established a Regulation in 2007 (EC 110/2007) that requires member states to develop Eel Management Plans (EMPs) for all eel habitats
Each EMP aims to reduce mortalities resulting from human activity “to permit with high probability the escapement to the sea”
An example of work within EMPs is the building of eel passes in zones where there are artificial obstructions in rivers which stop or reduce upstream migration of eels
It is also important to monitor eel escapement in order to fully protect the different migration pathways.
Interesting facts
The European eel can spend up to the first three years of its life drifting in the plankton being brought to the coasts of Europe on the Gulf Stream.
They then undergo metamorphosis and turn into glass eels – they are called this because they are transparent.
They then become pigmented and so darker in colour and are actively able to swim. They start to move into freshwaters in large numbers and are known as elvers.
The elvers become ‘yellow eels’ when they grow longer than 120mm. They spend much of their life as this before turning ‘silver’ and starting their long migration back to the Sargasso Sea.
The European Eel can grow up to 1 metre long and can live for over 20 years.
References
To find out more about their amazing life cycle, check out this video!
Jacoby, D. & Gollock, M. 2014. Anguilla anguilla. The IUCN Red List of Threatened Species 2014:e.T60344A45833138. http://dx.doi.org/10.2305/IUCN.UK.2014-1.RLTS.T60344A45833138.en
Jacoby, D et al. 2015. Synergistic patterns of threat and the challenges facing global anguillid eel conservation. Global Ecology and Conservation .Volume4 July 2015. Pages 321-333

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Anna Patel Volunteer for Zoological Society of London
How did you get involved?
I got involved with volunteering in the ZSL through an internship advertised on the ZSL website and other environmental websites. In this internship I gained experience in monitoring marine and freshwater species. |
Ocean traveller
The loggerhead is one of the most widespread of all the marine turtles and also the most highly migratory. This turtle's common name comes from its relatively large head, which contains powerful jaws. Loggerheads are the most common turtle in the Mediterranean, nesting on beaches from Greece and Turkey to Israel and Libya. However, many of their nesting beaches are under threat from tourism development.
Distribution and Habitat
The loggerhead sea turtle has a cosmopolitan distribution, nesting over the broadest geographical range of any sea turtle. It inhabits the Atlantic, Indian, and Pacific Oceans and the Mediterranean Sea. Loggerheads can be found hundreds of miles out to sea or in inshore waters. Coral reefs, rocky places, and ship wrecks draw large amounts of marine life and are great feeding areas.
Lifecycle
The sea turtle life cycle starts when a female lays its eggs on a nesting beach. Two months later a tiny hatchling makes its heads to the water and begins an epic 8,000-mile alone journey around the world. Young loggerheads will return to the coastal waters in about 6 to 12 years where they forage and continue to mature. A female reaches maturity when her carapace is 90cm (12-30 years). In nesting season the female will lay 2 -5 nests each with 100 eggs.
Threats
The main threats which affect marine turtles are: habitat loss and degradation, wildlife trade, collection of eggs and meat for consumption, incidental capture (bycatch), climate change, and pollution. The main cause of mortality is attributed to fisheries bycatch, and abandoned drift nets continue to drown loggerheads in unknown numbers (ghost fishing) & habitat loss or disturbance and pollution. Hatchlings use the natural light horizon, to reach the water when they emerge from the nest. Any other light sources such as beachfront lighting, street lights, light from cars, campfires etc. can lead hatchlings in the wrong direction.
Conservation
There is much work being undertaken to throughout the world through specialist programs and regional projects devoted to the conservation of marine turtles. Activities includes: monitoring the migration patterns of marine turtles; improving and supporting trade controls; protecting nesting sites and reducing bycatch and promoting smart fishing.
NGOs such as Greenrope and WWF are working to establish a fully representative network of protected areas in the Mediterranean and are collaborating with governments and partner conservation organizations to protect loggerhead nesting beaches in Turkey and Greece. Work is also underway in South Africa, Madagascar and Australia among other locations.
Another great example of conservation initiatives are carried on by Project Biodiversity in Cape Verde, extremely important hot spot for the nesting season of these animals. To know more: http://www.projectbiodiversity.org/
Interesting facts
Diet: Primarily carnivorous and feed mostly on shellfish that live on the bottom of the ocean. They eat horseshoe crabs, clams, mussels, and other invertebrates. Their powerful jaw muscles help them to easily crush the shellfish. In the their early age, in the period called “black period”, for the lack of knowledge about it, their feeding is related with their pelagic environment and their diet is based overall on jellyfish.
Male or female: The temperature of the nest determines a hatchling's gender. This is called Temperature-Dependent Sex Determination (TSD). Warmer temperatures produce mostly females, and cooler temperatures produce a majority of males. There is a pivotal temperature that produces an equal ratio of males and females. The temperature determining sex ratio differs between nest locations.
References
Dodd Jr., Kenneth C. Synopsis of the Biological Data on the Loggerhead Sea Turtle Caretta caretta (Linnaeus 1758), Biological Report 88(14) May 1988, (FAO Synopsis NMFS-149) Fish and Wildlife Services, U.S. Department of the Interior, 119 p.
IUCN/SSC Marine Turtle Specialist Group 1996. Caretta caretta. In: IUCN 2009. IUCN Red List of Threatened Species. Version 2009.2. www.iucnredlist.org. Downloaded on 23 December 2009.

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Claudia Volunteer for GreenRope
How did you get involved?
I got involved with volunteering in GreenRope through an advertisement on Facebook when in 2014 they were looking for volunteer to preserve a nest of Caretta caretta. Since that moment, I have done several experiences at local level and also abroad, in a project dedicated to the preservation of marine life in Greece. |
Masters of flying
Cory's Shearwaters are great travellers that can fly for hours gliding and soaring without active flying.
They have long migrations in a loop shape that go from their breeding places in Europe to the coast of South America, then to the coast of Namibia and South Africa, then they travel to the coast of North America and finally back to their breeding places again.
Distribution
Breeders from the Atlantic and Mediterranean have recently been considered as different species. The Atlantic species breed mainly in Azores, Madeira, Selvagem and the Canary Islands. The other species breed in islands of the Mediterranean Sea.
Both species have similar non-breeding range that extends through the Atlantic Ocean as far as the coast of Brazil and Uruguay.
Lifestyle
Cory's shearwaters are pelagic birds, - birds that spend most of their lives on the open ocean and rarely stop on land except to breed-. A young Cory's shearwater that flies for the first time won't land again after five or six years when it will breed for its first time.
They can be thousands of miles offshore and when they rest, they do so by floating on the water.
Threats
The population of both species appears to be decreasing. Their main threats are:
• Predation by invasive mammals at the breeding colonies
• Accidental bycatch by fisheries
• Light pollution at the colonies
• Poaching of chicks
• Shearwaters are especially vulnerable to invasive cats, rats or mice in the islands where they breed. As they are not use to this animals, they don´t avoid them and are easily trapped by them.
What conservation solutions have been put in place?
Portugal and Spain have led a pioneer project to design Marine Important bird Areas.
Following this project, new marine protected areas (SPA) have been designed under European legislation (the Birds Directive) in both countries. This is part of the Natura 2000 network.
Eradication programmes of rats and cats have been done at some small islands.
BirdLife support a new Common Fisheries Policy model of sustainable fishery and promotes a European Action Plan to reduce accidental bycatch.
Interesting facts
• A Cory's shearwater can fly 30,000 km in one year (Gonzalez-Solis et al. 2007)
• In 2015, a Cory's shearwater ringed in Tenerife (Canary Islands) was recovered in a beach of Massachusetts (SEO/BirdLife, 2015)
• Cory's Shearwaters are long-lived birds that can live more than 20 years (EURING, 2014)
References
Gonzalez-Solis, J., Croxal, J., Oro.D. y Ruia,X. 2007. Trans-equatorial migration and mixing in the wintering areas of a pelagic seabird. Front. Ecol. Environ 5: 297-301.
EURING. 2014. Longevity list: http://www.euring.org/data-and-codes/longevity-list

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Antonio Zamora Volunteer for ANSE
How did you get involved?
I got involved with volunteering in ANSE through a ringing course at the University given by this organization. Since then, I began to join them during the ringing sessions and now I'm involved in many different projects.
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