Nuno Oliveira

• MS Ecology and Environmental Management
• Senior Marine Conservation Officer at Sociedad Portuguesa Para o Estudo das Aves

Competition with fisheries and incidental capture in fishing gear are the major current threats for seabirds at sea. Fishing is a traditional activity in Portugal and is mainly composed of a great number of small vessels. Given the lack of knowledge on effects of the Portuguese fishing fleet on seabird populations, bycatch was assessed in mainland...

Seabirds are one of the avian groups facing the fastest and highest decline in population numbers around the world, suffering from many threats not only at sea but also on land. For burrow-nesting seabirds, the loss of adequate breeding habitat, human disturbance and competition with other species make the availability of adequate nesting burrows a...

Bycatch is one of the main threats to marine biodiversity, affecting ocean ecosystems at a worldwide scale. The main focus of bycatch studies has been on the impact of larger vessels, with few studies assessing the impact of artisanal fisheries. Moreover, bycatch studies are often limited to a small number of marine regions, and significant gaps st...

Few studies have explored local and global environmental effects on the demographic rates of small seabird species such as storm-petrels. We analysed ringing data (from 2011–2022) to investigate the demographic parameters of a breeding population of Band-rumped Storm-petrels Hydrobates castro, which nest on Farilhão Grande Islet, Berlengas archipel...

The common dolphin (Delphinus delphis) is the most abundant cetacean along the Western Iberian Peninsula, facing significant anthropogenic threats, particularly bycatch. This study analyses its distribution along the Portuguese mainland coast using vessel survey data (2005-2020) to identify hotspot areas and seasonal patterns in relation to sardine...

Modelling a species ecology and abundance provides important insights into its habitat preferences, population trends and distribution. This can be used to inform conservation efforts, highlighting populations at risk of extinction and regions in need of protection. Here, we studied how environmental factors relate to common dolphin (Delphinus delp...

Bycatch is a major cause of seabird mortality, yet most studies focus on industrial fisheries, with limited knowledge on artisanal fisheries. This study investigates the seasonal abundance of seabirds off the southern- eastern coast of mainland Portugal, their attendance at artisanal bottom-set net fisheries, and observed bycatch, using onboard obs...

O aumento das populações de gaivotas em áreas urbanas e costeiras é motivado pela abundância de alimento disponível e o carácter generalista das espécies. Diversas fontes de alimento associadas às atividades humanas podem ser amplamente exploradas por estas aves, especialmente nas cidades, onde resíduos urbanos, como restos de comida descartados em...

European Shag nesting monitoring The surveys to monitor the effect of marine litter on European Shag occur once a month between January and July each year. The minimum surveys required are four per year (mid February, mid April, mid May and early June). European Shag diet monitoring The surveys to monitor the effect of marine litter on European S...

According to estimates, almost 90% of seabirds have plastic in their stomachs. When they are not killed by ingestion, plastic threatens their survival and affects their habitats and their reproduction. Launched in October 2021 and until September 2024, the LIFE SeaBiL Project “Saving SeaBirds from marine Litter” intends to evaluate and reduce the i...

Colonial seabirds are highly sensitive to human disturbance, yet they frequently face significant pressure from tourism and other human activities. Barreta Island hosts the largest breeding colony of Audouin’s Gulls (Larus audouinii), along with breeding populations of Yellow-legged Gulls (Larus michahellis), Lesser Black-backed Gulls (Larus fuscus...

The After-Life Berlengas started in 2019. Here, we report the tasks carried out during 2019-2024 on seabird monitoring and conservation, biosecurity, control of invasive plants and monitoring of flora. Results on the research, volunteers, support, visitation and awareness activities are also presented. Data from before After-LIFE were also collated...

Bycatch in fishing gear is a worldwide problem that has often been pointed out as one of the main causes for the decline of several seabird species. One of the major difficulties in quantifying and qualifying the impact of fisheries on biodiversity has been the lack of information on fishing fleets characterization and fishing effort. The coast...

Seabirds are a relatively small group of birds but they have a global reach as they occur in every marine environment around the world. Due to their global abundance they are vital to understanding the status and ecology of marine environments. In recent decades, their status has been put under serious threat due to a wide range of anthropogenic...

Seabirds are severely threatened all around the world. Being a group of birds that mainly use the sea as their territory, there are many difficulties in studying its ecology and behaviour at sea. And as a result, conservation efforts have focused on breeding grounds. The RAM censuses are a monitoring methodology with great importance in the Iber...

PELAGO24 survey was carried between March 1st and March 23th 2024, onboard the R/V Miguel Oliver, in the Portuguese continental shelf and the Gulf of Cadiz Spanish shelf. The survey lasted 20 days at sea. A total of 1134 nautical miles (nmi) were tracked (71 transects), 26 pelagic fishing hauls were undertaken by the R/V Miguel Oliver and 29 fishin...

Although seabirds represent a relatively small portion of species among all birds, they have adapted to specific marine environments and conditions, which makes them good ecological indicators. The study of seabirds, their abundances, distributions and phenologies may be useful to assess the state of the ecosystems they inhabit, as well as provi...

Coastal inspections for beached birds allow the collection of information on the spatial and temporal distribution of strandings and evaluate the causes of mortality. The main goals of this work is to identify the potential threats that seabirds are subject to, understand the occurrence of a temporal pattern of strandings and identify the possible...

The current referential is intended to define the conditions that a small-scale fishery must meet in order to present the product to the consumer in a differentiated way. In this case, this assessment refers to fishery products caught by vessels operating hand operated pole-and-lines and set longline, within a partial zone of the Berlengas Biosp...

The increase in eco-tourism may bring opportunities but also challenges for nature conservation. A higher financial income may support the implementation of nature conservation and monitoring activities, which will benefit wildlife and habitats. Conversely, perturbation of breeding seabirds and trampling of native vegetation might increase. Public...

The availability of food of anthropogenic origin is one of the main causes for the increase of the Yellow-legged Gull Larus michahellis population and their establishment in urbanised areas. We tested the efficiency of food limitation measures in reducing the number of Yellow-legged Gulls attending and feeding on the landfill and fishing harbours i...

The Carpobrotus edulis, known as Hottentor Fig or Ice Plant is the species present in the Berlengas. Originally from South Africa, it was introduced in Portugal and several European countries and now it is considered one of the main invasive plant species. The Hottentot Fig was introduced in the Berlenga in the 1950s, with the purpose of support...

beached seabirds of 28 different species, 81% of which were Atlantic puffins (N=4043) followed by 5% (n=242) of Razorbills Alca torda (table 1). • The peak of puffins wreck was attained on the 2nd fortnight of January 2023, when nearly 75% of all beached birds were reported (figure 1). A slight delay of this peak was found when comparing Portuguese...

Anzol + aims to create a system for valuing the fishery products caught within the area of the Berlengas Nature Reserve (RNB), an integral part of the Berlengas Biosphere Reserve (UNESCO), and which applies to small-scale fishing and takes into account the environmental, economic and social sustainability criteria defined by the VAL + Matrix. Th...

The incidental capture (bycatch) of seabirds is a global conservation issue and a top threat to European species that demands urgent conservation and management action. Here, we present the first European review of seabird bycatch data, considering all fishing gears and data collection methods available in the region. We calculate seabird bycatch n...

Accidental capture in fishing operations (bycatch) is one of the main threats affecting seabirds worldwide. Available data on this issue remains limited and is often insufficient to evaluate the extent and characteristics of bycatch. The costs of placing independent observers on vessels, or gather verifiable and independent data via electronic syst...

Bycatch in fishing gear is one of the three top global threats for seabirds globally, both in terms of number of species affected and impact. Fisheries is one of the main activities carried out in the region of Ilhas Berlengas Special Protection Area (SPA) and it has an impact on seabird species that occur in the region, namely the Northern gann...

Anzol+ proposed to create a system for valuing the fishery products caught within the area of the Berlengas Nature Reserve (RNB), an integral part of the Berlengas Biosphere Reserve (UNESCO), and which applies to small-scale fishing and takes into account the environmental, economic and social sustainability criteria defined by the VAL + Matrix...

In the winter of 2022-23, a large number of dead and live seabirds, particularly Atlantic puffins Fratercula arctica, washed up along the mainland coast of Portugal. These massive mortality events can be associated to different causes (e.g., extreme weather conditions, food shortages, pollution or bycatch) and, when occurring frequently or at alarg...

The study involved interviews to boat skippers to evaluate bycatch in terms of type of gear and seabird species. More than a thousand questionnaires were carried out in the areas of the Eastern Algarve and Aveiro-Nazaré SPA.

This review evaluates the implementation of the Species Action Plan (SAP) for the Audouin's Gull for the period between 2011 and 2023. Overall, the implementation of the SAP has not been satisfactory, with some exceptions. Eleven of 15 countries delivered information on the SAP implementation. At a later stage, a twelfth country (Senegal) delivered...

PELAGO23 survey is part of the acoustic surveys of the PELAGO series (1995-2023), financed by national programs and by EU-DCF, are coordinated with the spring acoustic surveys from Spain and France and discussed and reported within ICES - WGACEGG (Working Group on Acoustics and Egg Surveys for small pelagic fish in NE Atlantic). The Portuguese acou...

Portuguese waters are a vital migratory corridor for European seabirds. Coast-based counts can monitor local and global populations and study the long-term trends in seabird populations. Using TRIM (Trends & Indices for Monitoring Data) and Generalized Additive Models (GAM) on ten years of a citizen science dataset of seabird counts from seven diff...

LIFE Ilhas Barreira - Conserving the Barrier Islands in Algarve to protect priority species and habitats (LIFE18 NAT/PT/000927) -- Os ecossistemas costeiros fornecem serviços de ecossistemas cruciais, tais como a estabilização da costa e a reciclagem de nutrientes, sendo também habitat para numerosas espécies. No entanto, o delicado equilíbrio dest...

LIFE Ilhas Barreira - Conserving the Barrier Islands in Algarve to protect priority species and habitats (LIFE18 NAT/PT/000927) -- Introduced mammals can pose serious threats to native seabird populations. On Deserta/Barreta Island in the Ria Formosa, south Portugal, the Audouin’s gull (Larus audouinii) and Little tern (Sternula albifrons) are thre...

LIFE Ilhas Barreira - Conserving the Barrier Islands in Algarve to protect priority species and habitats (LIFE18 NAT/PT/000927) -- Coastal ecosystems are crucial for their dynamic interplay between land and sea, and face increasing risks from biological invasion. The introduction of species beyond their natural ranges, may disrupt the delicate bala...

Marine protected areas (MPAs) are widely used tools for conservation and management. Their correct delimitation is challenging, especially when the target species are small, elusive and inconspicuous, as little data are generally available to adequately assess their distribution at sea. Therefore, currently designated MPAs may not effectively cover...

Bycatch is one of the main threats to seabird conservation. In Portugal, there are alarming estimates of seabirds bycaught per year in bottom gillnet fisheries, which get entangled during fishing operations, when the gear is close to the surface. In this study, a visual deterrent (scarybird) was tested in a fishing vessel operating bottom gillnets...

Several massive stranding events of seabirds have been documented during the last decades. Such events are likely due to extreme weather conditions, oil spills, other pollution, bycatch on fishing gears or shortage of food. A mass stranding of seabirds occurred on Portugal mainland during the winter of 2022-23 in Portugal mainland, affecting mos...

Fisheries pose a significant threat to seabirds through overfishing and bycatch. The European Shag Gulosus aristotelis is a threatened species in Portugal, whose main breeding site in the country is located in the Berlengas archipelago, a Special Protected Area (SPA). This region is also heavily dependent on fisheries and the fishing industry, with...

Over the last decades, the population size and breeding range of several gull species have increased worldwide. The unlimited amount of food of anthropogenic origin is thought to be the main vector for such increase. In Portugal, the Yellow-legged Gull Larus michahellis is the most abundant breeding gull species. There is some evidence of an expans...

LIFE Ilhas Barreira - Conserving the Barrier Islands in Algarve to protect priority species and habitats (LIFE18 NAT/PT/000927) -- The presence of predatory mammals on seabird breeding areas are a threat to the survival of eggs and chicks, and can drive birds to the abandonment of colonies. We collected data on presence, abundance, sesonal fluctu...

To improve knowledge on distribution of seabirds, especially the Audouin's Gull (Ichthyaetus audouinii), Yellow-legged Gull (Larus michahellis), and Balearic Shearwater (Puffinus mauretanicus), in the Algarve region, we performed boat-based surveys, and individual tracking of nesting seabirds on Deserta/ Barreta Island. Main areas used by seabirds,...

Invasive species are a major threat to island biodiversity, and their eradications have substantially contributed to the conservation of island endemics. However, the consequences of eradications on the trophic ecology of native taxa are largely unexplored. Here, we used the eradication of invasive black rats Rattus rattus and European rabbits Oryc...

The European Shag Phalacrocorax aristotelis is a threatened seabird species in Portugal. Knowledge about this population is limited, and currently there is no information about dietary needs and threats posed by fisheries. We studied the diet composition of Shags in the Berlengas archipelago, the largest breeding colony in the country, through the...

Berlengas archipelago is a UNESCO world heritage site and the only location where Armeria berlengensis is found. This species faces various threats, namely, human disturbance, the presence of Carpobrotus edulis, yellow-legged gull, common-rabbit, and black-rat populations. Thus, exclusion areas were installed, which blocked the access of most Gulls...

LIFE Ilhas Barreira - Conserving the Barrier Islands in Algarve to protect priority species and habitats (LIFE18 NAT/PT/000927)

Gulls are highly opportunistic seabirds, and the exploitation of fishery discards led to many population increases worldwide. We investigated the importance of fish in the diet of yellow-legged and Audouin’s gulls and assessed the influence of fishery discards in their feeding ecology. We collected pellets in four islands along the western Iberian...

Seabirds are marine predators known to forage in association with fisheries, however detailed knowledge on seabird-fishery interactions remains scarce in several regions of the world. We quantified seabird-fishery interactions and bycatch in central Portuguese coastal waters (NE Atlantic) between 2016 and 2018 in four gears: purse-seines, longlines...

Detailed information on diet and foraging ecology is scarce for most small seabirds such as storm petrels. In this study, we used molecular techniques, stable isotope analysis, and geolocators to study the diet, trophic ecology, and at-sea distribution of Madeiran storm petrels (Hydrobates castro) breeding in Farilhões Islet, Portugal, in 2015–2017...

Currently, seabirds are the most threatened group of birds, with their population decrease related with various anthropogenic activities. Being good ecological indicators, it is necessary to know its state of conservation. To this end, the RAM (Seabird and Marine Mammal Monitoring Network) census is a monitoring tool used by Iberian researchers t...

Bycatch in fishing gear is a worldwide problem that has often been pointed out as one of the main causes for the decline of several seabird species. One of the major difficulties in quantifying and qualifying the impact of fisheries on biodiversity has been the lack of information on fishing fleets characterization and fishing effort. The Special P...

O Plano de Conservação Pós-LIFE do projeto Life Berlengas foi desenvolvido pelos seus parceiros, com os contributos dos membros da comissão científica, e pretende identificar as prioridades de conservação para um período de 5 anos após a conclusão do projeto (2019 – 2024), de forma a maximizar os resultados obtidos e a promover a manutenção dos...

Seabirds are the most threatened group of birds and several actions have been Implemented to recover and re-establish seabird populations all over the world. Cory’s shearwater Calonectris borealis is the most abundant breeding seabird in the Azores archipelago and is vulnerable to invasive alien species, habitat loss and light pollution. In 2012,...

The spread of invasive alien species presents one of the major threats to biodiversity globally. This is the primary driver of biodiversity loss on islands and the second largest everywhere else. More than 109 species of birds have been driven to global extinction by invasive species since 1500, with rodents implicated in the extinction of at le...

The implementation of management measures in protected areas is very important to ensure the accomplishment of the conservation objectives. The recreational activities and visitation are important aspects in the socioeconomic component of protected areas so it is essential to collect and process information about the visitors of those areas, whi...

In this report, we present data and results about the impact of gull exclusion areas on the vegetation, especially on the endemic species Armeria berlengensis at Berlenga island, between 2015 end 2018. The data obtained allowed to evaluate the quantitative and qualitative evolution of the endemic flora in the study areas. Although the existing da...

Life Berlengas brought together five partners on a common mission: to contribute to the sustainable management of the Berlengas Islands Special Protection Area (SPA), aiming to conserve its habitats, endemic plants and seabird populations.

Introduced rodents cause major effects on insular local flora and fauna. The presence of black rats (Rattus rattus) on Berlenga Island can be a threat to endemic and native species, especially for plants. Understanding the trophic position of black rats is essential for management efforts and conservation actions. With this purpose, we studied the...

The concentration of the population in coastal regions, in addition to the direct human use, is leading to an accelerated process of change and deterioration of the marine ecosystems. Human activities such as fishing together with environmental drivers (e.g. climate change) are triggering major threats to marine biodiversity, and impact directly th...

Invasive alien species are a major threat to native insular species. Eradicating invasive mammals from islands is a feasible and proven approach to prevent biodiversity loss. We developed a conceptual framework to identify globally important islands for invasive mammal eradications to prevent imminent extinctions of highly threatened species using...

Table of islands, country or territory of ownership, invasive mammals and highly threatened species occurring on island, island rank reflecting conservation value, and timeframe assessed by socio-political survey in which an eradication could feasibly be initiated. Invasive mammal species listed are only those identified as having negative impact o...

Table of islands where no socio-political feasibility data was available during this study, country or territory of ownership, invasive mammals and highly threatened species occurring on island. Invasive mammal species listed are only those identified as having negative impact on highly threatened species and fall below island area and human popula...

Additional figures, tables and text supporting the main paper. (DOCX)

The European Shag is a resident seabird in mainland Portugal, although with a small population size with less than 400 adults. The main colony is located in Berlengas archipelago with an estimated population of 75 pairs. Besides its high conservation values, the Special Protection Area (SPA) of Ilhas Berlengas is an important site for commercial fi...

Seabirds are currently the most threatened bird group, with population declines related to several anthropogenic activities. Therefore, worldwide conservation efforts have been applied since the 80’s to preserve this group. 65 species of seabirds can be found in Portugal, with 20 species breeding in Portuguese territory. This high diversity is e...

The egg-oiling tested on action C.2 of this project was less effective (59,31% efficiency) than clutch destruction (78,5% efficiency). From 119 eggs (n=52 nests) oiled, 86,6% did not hatch. All hatchings (ca. de 13%) occurred in eggs oiled when aged less than 4 days. Mean time that oiled eggs were incubated was 34 days (d.p.=6, n=103, max.=49, m...

Under action C.2 of this project, egg-oiling in 2016 and egg-pricking in 2017 were tested as methods of control the gull colony productivity. Both egg-oiling and egg-pricking resulted in very high hatching success when compared to previously used egg destruction: 40.69% egg-oiling, 31.21 egg-pricking and 21.43% - 0% egg destruction in 2016 and 2...

The Berlengas archipelago is in the Atlantic Ocean, on the Portuguese continental shelf, on the western side of Iberian Peninsula, close to Cape Carvoeiro (Peniche). It distances approximately 5.7 miles from mainland. Berlengas was firstly classified as Natural Reserve in 1981. In 1998 this area was reclassified as Marine Reserve Area, increasing i...

Fisheries discards, the portion of a catch which is returned to the sea, contribute to target and non-target mortality and can reach large numbers in some regions, being recently considered as a global fisheries problem. The main objective of the present work was to characterize fisheries discards for purse seiners, demersal longliners and gilln...

In the project (between 2015 and 2018), 102 artificial nests were constructed for Cory’s shearwater, and 37 nests were occupied in the season of 2018. These nests were constructed in five areas of Berlenga Island: Melreu, Capitão, Flandres, Furado Seco and Quebradas. The Furado Seco is the area with a higher occupation rate, probably due to lowe...

Currently, seabird bycatch is a global important conservation issue and very often cited as one of the causes leading to population decline of different seabird species. Fisheries are one of the main economic activities carried out in Berlengas Islands Special Protection Area (SPA) and it is essential to understand the impact of this activity on...

The Action Plan was prepared through EuroSAP, a LIFE preparatory project, co-financed by the European Commission Directorate General for the Environment, the African-Eurasian Migratory Waterbird Agreement (AEWA), the MAVA Foundation and by each of the project partners, and coordinated by BirdLife International.

Marine Protected Areas (MPAs) have been established across all marine environments, though their coherence and effectiveness in protecting umbrella species remains unclear. We used a multi-model ensemble forecasting approach, on 8 years of at-sea censuses of 30 seabird species to identify candidate MPAs in the Portuguese coast, prioritizing importa...

Predation limits the breeding success of many colonial seabirds and is an important factor contributing for the decline of several species and burrowing breeding seabirds are quite vulnerable to predators. There are numerous predators of seabirds, many of which are invasive species on the islands where seabird colonies exists, such as rats, cats...

ABSTRACT: The Portuguese purse seine fishery, with average annual catches of 70 000 tonnes, operates mainly in coastal areas and targets small pelagic fish. A potential competition for resources may occur between the fishery and some species of marine mammals and seabirds as suggested by observed incidental catches of marine mammals and seabirds. F...

Bycatch in fishing gear is a worldwide problem that has often been pointed out as one of the main causes for the decline of several seabird species. One of the major difficulties in quantifying and qualifying the impact of fisheries on biodiversity has been the lack of information on fishing fleets characterization and fishing effort. The Speci...

The egg-pricking tested on action C.2 of this project in 2017 was less effective (68,8% efficiency) than clutch destruction (100% efficiency). From 113 eggs pricked, 14 hatched. Considering all the breading season, the overall hatching success in the treated areas was 31%, while in the egg destruction areas was 0%. Relaying did not occur in trea...

This document presents part of the results of the monitoring carried out on the island of Berlenga in 2015, 2016 and 2017 which included the conduct of to characterize the visitors of Berlenga Nature Reserve. Based on key survey questions, the Visitation Barometer was developed, a tool that illustrates the quality scale associated with the press...

Background In the regular wildlife monitoring action carried out in the summer of the past few years at the Berlenga Island, wild rabbits (Oryctolagus cuniculus) have been repeatedly found dead. However, the origin of those deaths was never investigated. Our aim was to investigate the cause of death of 11 rabbits collected between April and May 201...

The archipelagos of Madeira and Azores are the main nesting sites for seabirds, harbouring considerable populations of some species, such as the world's largest population of Cory’s Shearwater and the largest colony in the Atlantic of Bulwer’s Petrel. The RAM censuses are an Iberian monitoring tool that allows obtaining data on seabirds occurrin...

Unwanted catches are a pervasive problem of world fisheries, representing a wasteful use of marine resources. The 2013 Reform of the EU Common Fisheries Policy has made a legal commitment to end discarding by implementing the Landings Obligation for those species subject to TAC or Minimum Conservation Reference Size. To mitigate the problem, the us...

Purse seine fisheries are globally distributed but scarcely understood in regard to their impacts on non-target species. Knowledge on bycatch issues was restricted to interactions with purse seine vessels targeting tuna and the conservation actions focused mainly on megafauna such as dolphins. We reviewed the available information on seabird bycatc...

pure seine fishery; cetaceans; seabirds; competition for food resources; spatial and dietary overlap.

Berlengas archipelago is one of the most important breeding sites on Portugal mainland coast. Six seabird species regularly breed on these islands: Cory’s Shearwater, Band-rumped Storm-petrel, European Shag, Yellow-legged Gull, Lesser Black-backed Gull and Common Murre. To respond to the insufficient knowledge of seabird population size, trends,...

This report is an addendum to the December 2015 technical report in which it was not possible to present data on the size of the yellow-legged gull breeding population from the Farilhões Islands. For better understanding of the historical evolution of the population, we present the December 2015 report results updated with the data collected in 2...