Summary:

META (Marine mammal and Ecosystem: anthropogenic Threat Assessment) is a two year project funded by the Portuguese Republic through Fundo Azul, coordinated by the Madeira Whale Museum (MWM), and with partners in Azores from the Institute of Marine Research (IMAR), Lisbon from Instituto Gulbenkian de Ciência(IGC) and Sagres from Mar Ilimitado.

The objective of META is to study how human threats affect populations of resident cetaceans, so that proper management measures can be applied. Specific objectives will characterize and define the distribution of those human threats such as marine traffic, ambient noise and marine litter. Further, we need to estimate which are the potential changes induced by those threats within the studied resident cetacean population, first we are going to study behavioural changes in their general distribution and individual movement and second physiological changes using three parameters: genetic health, contaminants and stress hormones. All those changes can potentially impact their vital rates such as survival and reproductive rates. Finally, we want to evaluate the socio-economic impact and carrying capacity of whale watching activity (WW), trying to apply a proper WW management.

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Justification

Marine top predators such as marine mammals are key elements of the ecosystem, which are normally used as indicators of a specific area environmental state. Understanding both the distribution of predators and the spatially explicit cumulative impacts of multiple stressors on resident populations is fundamental. Both in Azores and Madeira long-term monitoring of cetaceans has been held. Sperm whales (Physeter macrocephalus) use the Azores as a foraging and calving ground especially by matriarchal groups that return there every year, staying from weeks to months foraging in the area, but also by mature males (Silva et al. 2014). Bottlenose dolphins (Tursiops truncatus) are considered resident in both archipelagos (Silva et al. 2009; Alves et al. 2013; Dinis et al. 2016), in Madeira there are also resident groups of short-finned pilot whales (Globicephala macrorhynchus) (Alves et al. 2015).

Human activities can create significant impacts that could affect marine mammals. Some of these activities do not even need to happen in the sea, but their consequences can be noted there, in an environment without physical boundaries. Most of the products that we use daily are disposables or contain chemicals, which can find their way out to the sea becoming marine litter or contaminants. In Madeira resident cetacean species are distributed within a corridor highly used by large ships (mainly cargo and cruise ship) (Cunha et al. 2017). In Azores, background noise was found to potentially affect temporally long-range communications in baleen whales (Romagosa et al. 2017). Whale watching (WW) activity can potentially affect the behaviour of marine mammals. The way boats are manoeuvring near the target species is very important, as some boats produce loud sound at low and/or high frequencies, which could affect several cetacean species (Oliveira et al. 2009). If properly managed this activity can be a potent tool for the conservation of whales and dolphins, through research, education and economic growth.

In mainland Portugal, WW regulation came into force in 2006 (DL 9/2006, 6 Janeiro), however there is little information on cetacean species occurrence and distribution and there is no evaluation of the carrying capacity of the WW activity and their potential impacts. In Azores the WW activity started in 1993 and rapidly became one of the most important tourism activities in the region, currently involving 26 enterprises and well over 30.000 clients per year (Oliveira et al. 2007; Sequeira et al. 2009). Today the activity in the Azores targets mainly sperm whales, especially during the summer months. In the presence or approach of whale watching boats, sperm whales change their behaviour (e.g. increase in respiration intervals, swimming speed, aerial displays) (Magalhães et al. 2002, 2007). In 2007 in Madeira, around 58.000 tourists participated in whale watching activity and moved around 1.5 million euros annually (Ferreira 2007). Short-term effects have also been observed in small dolphins, with an increase of velocity when whale watching boats approached them (Ferreira 2007). The activity was regulated with the Decreto Legislativo Regional nº15/2013/M. An exclusion area was enforced in 2014 where no whale watching can take place. It is a key area for both resident populations of bottlenose dolphins and short-finned pilot whales.

The behavioural changes recorded in both regions indicate some degree of disturbance, although the biological relevance of these behavioural changes is unknown. Cumulative exposure to chronic stressors could scale up to induce physiological changes and have effects at the population level. Indeed, stress can lower immune response and make the animals more vulnerable to infectious pathogens which can in turn affect their survival and/or reproductive rates.

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