• history

    of sado population

    1863

    Oldest record in history

    José Vicente Barbosa du Bocage was the first writer who described the existence of dolphins in Sado estuary.

    1980

    First scientific records

    The first scientific records about the dolphins in Sado estuary began in 1980 with the works of Teixeira &Duguy (1981), Hussenot (1982), Dos Santos (1985) e Dos Santos & Lacerda (1987).

    1998

    The Day the Dolphin Flew

    Twenty years ago one of the Sado dolphins, "Asa", flew over the Sado estuary, hoisted by a Portuguese Air Force helicopter. This was the solution to save him after he was trapped in a river mat, most likely while hunting.

    2005

    Population decreased to the smallest number

    In 2005 the population of dolphins in Sado estuary decreased to 22 individuals. However we can consider this year as a wind of change, because from this date on the population increased its numbers and mortality rates of calf's decreased, since 2005 have born 17 dolphins and only 4 are not present in the population.

    2015

    BEGINNING OF THE Awareness Project

    From 2015 the project "Sado Dolphins" was put in works, promoted by "Tróia Natura" in partnership with ICNF (Natural park reservation), this project aims to alert all navigators in Sado estuary to adopt good behaviour and attitude in the presence of dolphins. During the summer months is very common to see the protection team in action.

    2018

    THEY'RE ABOUT 31 DOLPHINS

    The resident population of dolphins from Sado estuary as nowadays about 30 dolphins. 22 adults, from which 8 females, 5 males and 9 of them not yet sexual known. 4 Juveniles and 4 calf's complete the population.

  • Conservation

    Management & behaviors

    Conservation

    a commitment with life

    "The sea, once it casts its spell, holds one in its net of wonder forever."Jacques-Yves Cousteau

    Despite the bottle nose dolphins are classified as "non endangered species", in Portugal the resident population of dolphins are considered "fragile" because it's low number of individuals, consanguinity problems and other factors of the population like slow reproduction. It's all about the only resident population of dolphins living in Portugal and one of the few 3 in all Europe. That's why it as so much protection and all studies for now aim to their well being and conservation. "Know to protect" is the goal, and all its dolphin watching is regulated and protected by a "code of conduct".

    Status

    Tursiops truncatus

    "The sea unifies, it's men's last hope. Now more than ever the meaning of this words aims to alert us that "we are all in the same boat."Jacques-Yves Cousteau

    Bottle nose dolphins are classified as "non endangered species" (UICN, 2003). in Portugal and Europe. It's currently protected by international laws such as convention (CITES); that aims to the conservation of wildlife and natural habitats. Berna convention; and agreement of the conservation of wildlife in it's habitat like the Black Sea, Mediterráneo and Atlantic marine adjacent areas (ACCOBAMS); "Habitats Directive" and other regulatory laws.

    Plan of action

    PLAN OF ACTION

    "Since birth, men carries the weight of gravity on its shoulder. It's stuck to Earth. But man only needs to dive below surface and it's free."Jacques-Yves Cousteau

    Plan of action for the conservation of wildlife and the resident population of dolphins in Sado estuary, aims to define a set of strategies for the conservation and protection of the population. On this sense the Natural reserve of Sado estuary (RNES) as gathered since 2008 some meeting with partners in order to define the basis of this plan of action. One of the projects developed in this plan is "Roazes do Sado project" that aims to alert all navigators before and during the dolphin watching.

    Sensibilização

    Projecto roazes do Sado

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    2014

    Our nice super title

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    2015

    Our nice super title

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    2016

    Our nice super title

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  • biology

    evolution & anatomy

    Species

    Tursiops truncatus

    Their comum name in Portuguese is "roaz corvineiro" and scientific name of the specie is Tursiops truncatus. The name "Roaz" comes from their habits of making holes in fisherman nets in order to steal the fish. "Corvineiro" it's the name of a fish they like a lot. Their well known from other species because of their "darker gray color" on the Dorso and because they are bigger than others. They can reach like 600kg and accomplish a size of about 4 meters length.

    Echolocation

    Comunication | Orientation

    Dolphins are specialized in acustic sounds. The way they interact with eachother and the surrounding depends on their sensorial sistem. It's tru their below jaw that they receive the sounds, because external earrings would not be functional. They use echolocation in order to detect their position and/or distance between objects and other animals (for example fish shoal). They use ultrasonic waves that reflect on target and come back to them in form of echo. They communicate through whistles crackling or other pulse sounds.
    Listen the sound of a dolphin.


    behavior

    Simpatic dolphins

    They are pretty sociable animals and they live mostly in groups. It's common to see them socialize with other coastal dolphins. They are very active at the surface, that's why we can observe some jumps and acrobatic movement. They are for sure very curious, what makes them approach to boats and in some times they go with the boat, like a race for them.

    Actividade

    activity patterns

    Sado dolphins have 4 distinct patterns: traveling, feeding, socialisation and resting. Traveling is the most common observations. Categorised by them emerging in group and in one direction usually with short submersions. Feeding, perhaps their second most frequently seen behaviour. Categorised by quick movement and erratic at the surface, most times we can observe their cooperation in hunting. Socialisation In Socialisation habits is usual to observe behaviours of great interaction between them, fisical contact and sinchronized jumps, normally in groups of 2 or 3 individuals. When observed slow movement or non movement at all at surface on a group with a distinct direction, they are resting.

    Reproduction

    In 2017 were born 3 dolphins

    Between 8 and 12 years old, dolphins are sexual ready for mating. Gestation period is about 12 months, and can only born one calf. All efforts are made from the mother to ensure the survival and growth of the baby. Dependence of the mother can last between 2 and 6 year's, what implies gestation break's of 2to 3 years.

    Feeding

    "What comes in the net, is fish"

    Considered opportunist and generic, they can adapt their diets depending on availability of the prey's. In Sado estuary it's common to see them feeding on "mullets", "seabass", "cuttlefish", octopus", seafood in general. They feed in groups, cooperating with each other, they hunt mainly in shallow water because it's easier to catch their prey's. It's very common to see them throwing food in the air. One of the reason they choose Sado estuary to live, is because it's biodiversity and abundance of fish species.

  • Bibliography

    Research Articles & Master's thesis

    chronologically ordered



    Alves, I.S.C. 2017. Underwater vocalization of bottlenose dolphins in the region of the Sado estuary: acoustic features and occurence patterns. Tese de Mestrado, Faculdade de Ciências da Universidade de Lisboa. 38 pp.


    Costa, M. 2017. Estudo da utilização espácio-temporal do estuário do Sado pela população residente de roazes (Tursiops truncatus), com recurso a um método goniométrico. Tese de Mestrado, Faculdade de Ciências da Universidade de Lisboa. 60 pp.


    Luís, A. R., Couchinho, M. N., & Dos Santos, M. E. (2016). A Quantitative Analysis of Pulsed Signals Emitted by Wild Bottlenose Dolphinsa. PloS one, 11(7), e0157781. doi:10.1371/journal.pone.0157781


    Ferreira, P.A.C., 2012. Avaliação de potenciais impactos da actividade da pesca na população de roazes do Estuário do Sado. Tese de Mestrado, Faculdade de Ciências da Universidade de Lisboa. 39 pp.


    Martinho, F.O.M.M., 2012. Residency and behavioural patterns of coastal bottlenose dolphins (Tursiops truncatus) in the Arrábida and Tróia shores (Portugal). Tese de Mestrado, Faculdade de Ciências da Universidade de Lisboa. 80 pp.


    Rocha, A.I.L. 2012. Vocalizações dos golfinhos-razes (Tursiops truncatus) residentes na região do estuário do sado e estudo da influência do tráfego marítimo nos padrões de emissão dos assobios. Dissertação de Mestrado em Ciências do Mar – Recursos Marinhos, Instituto de Ciências Biomédicas Abel Salazar, da Universidade do Porto. 97 pp.


    Brito, C., & Sousa, A. (2011). The environmental history of cetaceans in Portugal: ten centuries of whale and dolphin records. PloS one, 6(9), e23951.


    Ferreira, M.C.V. 2010. Movimentos e atividades dos golfinhos-roazes (Tursiops truncatus) na zona terminal do estuário do Sado e possíveis influências ecológicas. Mestrado em Ecologia Marinha. Universidade de Lisboa, Faculdade de Ciências, Departamento de Biologia Animal, Lisboa. 56 pp.


    Grilo, S.I.B.E., 2010. Estudo da utilização do território pela população de roazes (Tursiops truncatus) do estuário do Sado a partir de dados obtidos em embarcações de Dolphin Watch. Tese de Mestrado, Faculdade de Ciências da Universidade de Lisboa. 86 pp.


    Sequeira, M.; Matias S., Farinha J.C., Gaspar R., Silva C., Augusto J., Ferreira C., Fonseca M.J., Narra P. e Luís, A.R. 2009. Bases para o plano de ação para a salvaguarda e monitorização da população de roazes do estuário do Sado. Instituto da Conservação da Natureza e da Biodiversidade: 80 pp.

    Luís, A.R.F. 2008. Avaliação do impacto de construções portuárias no comportamento e no ambiente acústico da população de golfinhos-roazes (Tursiops truncatus) do estuário do Sado. Mestrado em Ecologia e Gestão Ambiental. Universidade de Lisboa, Faculdade de Ciências, Departamento de Biologia Animal, Lisboa. 110 pp.


    Silva, C. 2008. A população residente de Tursiops truncatus num quadro de gestão integrada do estuário do Sado: Proposta de um acordo voluntário. Tese de Mestrado, Faculdade de Ciências da Universidade de Lisboa. 114 pp.


    Augusto, J.F.F. 2007. Análise da estrutura social, da composição dos grupos e associações nos golfinhos-roazes (Tursiops truncatus) residentes na região do Sado. Mestrado em Ecologia Marinha. Universidade de Lisboa, Faculdade de Ciências, Departamento de Biologia Animal, Lisboa. 65 pp.


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