Fishers’ Behaviour in Response to the Implementation of a Marine Protected Area

Marine Protected Areas (MPAs) have been widely proposed as a fisheries management tool in addition to their conservation purposes. Despite this, few studies have satisfactorily assessed the dynamics of fishers’ adaptations to the loss of fishing grounds. Here we used data from before, during and after the implementation of the management plan of a temperate Atlantic multiple-use MPA to examine the factors affecting the spatial and temporal distribution of different gears used by the artisanal fishing fleet. The position of vessels and gear types were obtained by visual surveys and related to spatial features of the marine park. A hotspot analysis was conducted to identify heavily utilized patches for each fishing gear and time period. The contribution of individual vessels to each significant cluster was assessed to better understand fishers’ choices. Different fisheries responded differently to the implementation of protection measures, with preferred habitats of target species driving much of the fishers’ choices. Within each fishery, individual fishers showed distinct strategies with some operating in a broader area whereas others kept preferred territories. Our findings are based on reliable methods that\ud can easily be applied in coastal multipurpose MPAs to monitor and assess fisheries and fishers responses to different management rules and protection levels. This paper is the first in-depth empirical study where fishers’ choices from artisanal\ud fisheries were analysed before, during and after the implementation of a MPA, thereby allowing a clearer understanding of the dynamics of local fisheries and providing significant lessons for marine conservation and management of coastal systems

Parent–offspring dietary segregation of Cory’s shearwaters\ud breeding in contrasting environments

In pelagic seabirds, who often explore distant food resources, information is usually scarce on the level of trophic segregation between parents and their offspring.\ud To investigate this issue, we used GPS tracking, stable\ud isotopes and dietary information of Cory’s shearwaters\ud Calonectris diomedea breeding in contrasting environments.\ud Foraging trips at Selvagem Grande (an oceanic island)\ud mainly targeted the distant African coast, while at Berlenga\ud island (located on the continental shelf), shearwaters foraged mainly over nearby shelf waters. The degree of isotopic segregation between adults and chicks, based on\ud d13C, differed markedly between the two sites, indicating\ud that adult birds at Selvagem fed their chicks with a mixture\ud of shelf and offshore pelagic prey but assimilated more\ud prey captured on coastal shelf waters. Isotopic differences\ud between age classes at Berlenga were much smaller and\ud may have resulted from limited dietary segregation or from\ud age-related metabolic differences. The diet of shearwaters\ud was also very different between the two colonies, with\ud offshore pelagic prey only being detected at Selvagem\ud Grande. Our findings suggest that spatial foraging constraints influence resource partitioning between pelagic\ud seabirds and their offspring and can lead to a parent–offspring dietary segregation

Effects of environmental variability on different\ud trophic levels of the North Atlantic food web

The effects of environmental change on the biodiversity, structure and functioning of\ud marine ecosystems is still poorly understood. In fact, very few studies have focused on changes in\ud the at-sea foraging tactics of pelagic seabirds in relation to environmental stochasticity. Aiming at\ud filling this knowledge gap, from 2005 to 2010 we directly measured the influence of climate (as\ud driven by the North Atlantic Oscillation phenomenon) on (1) marine productivity (i.e. chlorophyll\ud a concentration), (2) fish prey abundances and (3) the foraging behaviour of a top marine predator,\ud the Cory’s shearwater Calonectris diomedea borealis. There was a dramatic change in the foraging\ud strategy of the birds during 2010, which seems to be mostly related to a climatic event that\ud occurred during the winter of 2009 to 2010. This event had a negative impact on the productivity\ud of the surroundings of the breeding colony and decreased the abundance of pelagic prey fish,\ud which in turn altered the spatial, feeding and trophic ecology of Cory’s shearwater and decreased\ud their reproductive success. However, the negative trend in the abundance of pelagic prey (estimated\ud from acoustic surveys and commercial fisheries landings) may be of concern because it\ud does not seem to be only related to the climatic event of 2010. Long-term monitoring of the interactions\ud between top predators, their prey and lower strata of the food web is crucial for a comprehensive\ud assessment of the impacts that environmental variation may have on coastal ecosystems\ud worldwide

AVALIAÇÃO DE POTENCIAIS IMPACTOS DA ACTIVIDADE DA PESCA NA POPULAÇÃO DE ROAZES DO ESTUÁRIO DO SADO

O estuário do Sado apresenta uma elevada riqueza biológica e é, um habitat de extrema importância para uma população de golfinhos-roazes (Tursiops truncatus), a qual constitui uma das poucas residentes em estuários europeus. Esta população depende do estuário em particular para a alimentação, sendo o choco (Sepia officinalis) uma das \ud suas presas preferenciais. Dada a importância conservacionista e ecológica que esta espécie representa, pretendeuse com este trabalho avaliar os possíveis impactos da actividade da pesca na população de roazes. Para o efeito foram realizados censos de artes de pesca fundeadas no interior do estuário do Sado e inquéritos aos pescadores de várias comunidades do estuário. As artes de pesca mais utilizadas no estuário são o tresmalho e os covos. Através da avaliação do esforço de pesca nas diferentes zonas de amostragem, observou-se que a distribuição de covos se encontra maioritariamente entre o Canal de Alcácer e o Canal da Gâmbia. Quanto aos tresmalhos foram registados ao longo de todo o Canal Sul, no Canal da Comporta, no Canal de Alcácer até à Ilha do Cavalo e próximo dos estaleiros \ud da Lisnave (Canal Norte). Através da análise das zonas de maior incidência de artes de pesca e de ocorrência de \ud golfinhos-roazes, verificou-se que há uma sobreposição destas zonas, contudo, pela análise dos inquéritos efectuados aos pescadores não se verifica a existência de conflitos entre estes e os golfinhos. Estes resultados permitem-nos concluir que, apesar da actividade piscatória no estuário do Sado ser intensa, não se verificam impactos significativos sobre os roazes. No entanto, no futuro, a possível diminuição dos recursos disponíveis para a pesca e para a alimentação dos roazes ao longo do tempo, poderá conduzir a uma competição por recursos

Common dolphin (Delphinus delphis) habitat preferences using data from two platforms of opportunity

Cetaceans are difficult to observe in the wild, and demand complex logistics for dedicated collection of biological data. As such, the distribution of most cetacean species is still poorly understood. Ecological niche models are useful in studying species distributions and their ecological determinants, and platforms of opportunity (e.g. commercial nautical operators) can provide an alternative source for that data in cetaceans. In this study, we modelled common dolphin (Delphinus delphis) habitat preferences using ecological niche modelling and presence data obtained from distinct platforms of opportunity in two different areas in the Portuguese coast (west and south mainland Portugal) for the period 2005e2007. Models from southern Portugal were projected to western Portugal and vice-versa, to check for robustness in predicting the species ecological niche. Our results show that data from platforms of opportunity can result in robust ecological models and provide extremely useful information on cetacean ecology. We found that common dolphins exhibit a patchy distribution pattern over the Portuguese coastline, and identified key habitats for their occurrence. The most important variable associated with this species’ distribution was chlorophyll concentration which, given the results from previous research, we hypothesise reflects an ecological specialisation on pelagic schooling fish. Given that the most abundant schooling fish species in Portugal is increasingly overexploited and in constant decline, more attention should be given to the conservation of common dolphin in Portuguese waters

The role of breeding experience on the\ud foraging specialization of a pelagic marine\ud predator, the Cory's sheawater

Experience is believed to be an important factor determining the foraging\ud success of animals, but there are still very few studies investigating how foraging\ud abilities develop over time. In this study, the spatial distribution and foraging tactics\ud of inexperienced and experienced individuals of a Procellariiform seabird species, the\ud Cory’s shearwater (Calonectris diomedea borealis) breeding on the Portuguese\ud continental shelf was compared. Kernel analysis and a multivariate analysis\ud (MADIFA) showed that while the experienced birds were relying on known static\ud features such as the bathymetry of the area, inexperienced birds were using larger\ud areas that were explained by different static and dynamic variables each year. The\ud foraging areas of the two groups overlapped less and less for each year, while stable\ud isotope signatures were becoming more and more similar, as inexperienced birds were\ud foraging on higher trophic prey closer to the coast, like the experienced birds. Linear\ud mixed models comparing home ranges and foraging areas calculated for each group\ud showed that the experienced birds were in general more successful in detecting\ud favourable foraging grounds, except in 2011, when the results showed the opposite.\ud Interestingly, the reproductive success of the inexperienced birds was significantly\ud higher than for experienced birds during that season