Shellfish farming is an expanding segment of marine aquaculture, but the impact of this industry on coastal cetacean species is only beginning to be considered. The interaction between mussel farming and coastal cetaceans in one of the world’s leading producers of this bivalve (Galicia, NW Spain) was studied. Specifically, the habitat use of common bottlenose dolphins (Tursiops truncatus) was evaluated in relation to environmental, geographical, and anthropogenic variables. Over a period of 22 months spent in the field, 154 daily boat surveys and 353 common bottlenose dolphin encounters were done. Results of this study confirm that areas of mussel production are frequently utilized by common bottlenose dolphins. Of the investigated factors, shellfish farms appeared to have a clear effect, with increased bottlenose dolphin occurrence at mussel farm locations and in waters close to the aquaculture zones. These observations contrast with previous studies where the occurrence and distribution of coastal cetacean species decreased in association with shellfish aquaculture representing a source of habitat loss and causing potentially negative effects. These differences suggest that the interactions between shellfish aquaculture and cetaceans are affected by the culture method and cetacean species involved. The positive relationships between dolphins’ occurrence and mussel aquaculture zones are presumably the result of large aggregations of fish species around mussel rafts, which provide high densities of high-quality prey for dolphins. This study provides new insights into the understanding of how shellfish aquaculture influences coastal dolphins and hence support the design of policies aimed at implementing ecosystem management principles.
We estimated the current level of knowledge concerning several biological characteristics of the Mediterranean marine fishes by carrying out a gap analysis based on information extracted from the literature, aiming to identify research trends and future needs in the field of Mediterranean fish biology that can be used in stock assessments, ecosystem modeling and fisheries management. Based on the datasets that emerged from the literature review, there is no information on any biological characteristic for 43% (n = 310) of the Mediterranean fish species, whereas for an additional 15% (n = 109) of them there is information about just one characteristic. The gap between current and desired knowledge (defined here as having information on most biological characteristics for at least half of the Mediterranean marine fishes) is smaller in length-weight relationships, which have been studied for 43% of the species, followed by spawning (39%), diet (29%), growth (25%), maturity (24%), lifespan (19%) and fecundity (17%). The gap is larger in natural mortality for which information is very scarce (8%). European hake (Merluccius merluccius), red mullet (Mullus barbatus), annular seabream (Diplodus annularis), common pandora (Pagellus erythrinus), European anchovy (Engraulis encrasicolus), European pilchard (Sardina pilchardus) and bogue (Boops boops) were the most studied species, while sharks and rays were among the least studied ones. Only 25 species were fully studied, i.e. there was available information on all their biological characteristics. The knowledge gaps per characteristic varied among the western, central and eastern Mediterranean subregions. The number of available records per species was positively related to total landings, while no relationship emerged with its maximum reported length, trophic level and commercial value. Future research priorities that should be focused on less studied species (e.g. sharks and rays) and mortality/fecundity instead of length-weight relationships, as well as the economy of scientific sampling (using the entire catch to acquire data on as many biological characteristics as possible) are discussed.
Targets and limits for long-term management are used in fisheries advice to operationalize the way management reflects societal priorities on ecological, economic, social and institutional aspects. This study reflects on the available published literature as well as new research presented at the international ICES/Myfish symposium on targets and limits for long term fisheries management. We examine the inclusion of ecological, economic, social and institutional objectives in fisheries management, with the aim of progressing towards including all four objectives when setting management targets or limits, or both, for multispecies fisheries. The topics covered include ecological, economic, social and governance objectives in fisheries management, consistent approaches to management, uncertainty and variability, and fisheries governance. We end by identifying ten ways to more effectively include multiple objectives in setting targets and limits in ecosystem based fisheries management.
The contribution by women to fisheries economies globally continues to be overlooked, in part, because “fishing” is often narrowly defined as catching fish at sea, from a vessel, using specialized gears. Both men and women are involved in fisheries, but often in different roles and activities. Fisheries research, management, and policy have traditionally focused on direct, formal, and paid fishing activities—that are often dominated by men, ignoring those that are indirect, informal, and/or unpaid—where women are concentrated. This has led to a situation where men's and women's contributions to fisheries are not equally valued or even recognized and has resulted in women being largely excluded from fisheries decision-making processes. Here, we examine the contributions by women in the fisheries sector of five globally significant marine fishing countries—Mexico, Peru, Senegal, South Africa, and Vietnam. These countries each have strong links between livelihoods and marine capture fisheries, yet represent different geographic, socioeconomic, and governance contexts. Through a synthesis of existing data, case studies, and consultation with local experts, we found that the contribution by women to the fisheries of these five countries is substantial. However, this investigation also revealed major gaps in understanding of gender inequalities in the fisheries sector and the need for better gender-disaggregated data to inform fisheries policy.
The ‘Wild Seafood’ Provisioning Service (WSPS), on which commercial fisheries rely, is probably one of the best studied marine ecosystem services due to its economic relevance and because extensive information sources exist for assessment purposes. Yet, the indicators often proposed are not suitable to describe the capacity of the ecosystem to deliver the WSPS. Therefore this study proposes surplus production (SP), a well-established concept in fisheries science, as the basis to calculate the capacity of marine ecosystems to provide the WSPS. SP is defined as the difference between stock production (through recruitment and body growth) and losses through natural mortality. This is, therefore, the production of the stock that could be harvested sustainably without decreasing the biomass. To assess the sustainability of the exploitation of the WSPS we also developed an indicator for this based on SP and compared it to existing fisheries management indicators. When both SP-based indicators showed a decreasing trend, contrasting with an increasing trend in the existing fisheries management indicators, the calculation of the SP-based indicators was scrutinized revealing that the weighting of the stocks into an aggregated indicator, strongly determines the indicator values, even up to the point that the trend is reversed. The aggregated indicators based on SP-weighted stocks can be considered complementary to existing fisheries management indicators as the former accurately reflect the capacity of the commercial fish to provide the WSPS and the sustainability of the exploitation of this service. In contrast the existing fisheries management indicators primarily reflect the performance of management towards achieving fisheries-specific policy goals.
This is the first study to assess the social costs of marine debris washed ashore and litter left behind by beach visitors along different European coasts. Three identical surveys, including a discrete choice experiment, are implemented at six beaches along different European coastlines: the Mediterranean Sea in Greece, the Black Sea in Bulgaria and the North Sea in the Netherlands. Beach visitors are asked for their experiences with beach litter and their willingness to volunteer in beach clean-up programs and their willingness to pay an entrance fee or increase in local tax to clean up marine litter. Significant differences are found between countries. This has important implications for the size and transferability of the estimated social costs of marine litter across Europe.
Plastic marine debris is a global problem, but due to its widespread and patchy distribution, gathering sufficient samples for scientific research is challenging with limited ship time and human resources. Taking advantage of public interest in the impact of plastic on the marine environment, successful Citizen Science (CS) programs incorporate members of the public to provide repeated sampling for time series as well as synoptic collections over wide geographic regions. A key challenge with any CS program is to ensure standardized methods and quality control so that the samples and data can legitimately be compared and used in peer-reviewed research. This article describes several successful examples and outlines suggestions for projects cooperating with citizen scientists to provide reliable samples and accurate data, with benefits to science, citizen scientists, and society in general.
Plastic in the global oceans fulfills two of the three conditions for pollution to pose a planetary boundary threat because it is causing planetary-scale exposure that is not readily reversible. Plastic is a planetary boundary threat if it is having a currently unrecognized disruptive effect on a vital Earth system process. Discovering possible unknown effects is likely to be aided by achieving a fuller understanding of the environmental fate of plastic. Weathering of plastic generates microplastic, releases chemical additives, and likely also produces nanoplastic and chemical fragments cleaved from the polymer backbone. However, weathering of plastic in the marine environment is not well understood in terms of time scales for fragmentation and degradation, the evolution of particle morphology and properties, and hazards of the chemical mixture liberated by weathering. Biofilms that form and grow on plastic affect weathering, vertical transport, toxicity, and uptake of plastic by marine organisms and have been underinvestigated. Laboratory studies, field monitoring, and models of the impact of weathering on plastic debris are needed to reduce uncertainty in hazard and risk assessments for known and suspected adverse effects. However, scientists and decision makers must also recognize that plastic in the oceans may have unanticipated effects about which we are currently ignorant. Possible impacts that are currently unknown can be confronted by vigilant monitoring of plastic in the oceans and discovery-oriented research related to the possible effects of weathering plastic.
We provide evidence for temporal displacement of illegal discharges of oil from shipping, a major source of ocean pollution, in response to a monitoring technology that features variation in the probability of conviction by time of day. During the nighttime, evidence collected by Coast Guard aircraft using radar becomes contestable in court because the nature of an identified spot cannot be verified visually by an observer on board of the aircraft. Seasonal variation in time of sunset is used to distinguish evasive behavior from daily routines on board. Using data from surveillance flights above the Dutch part of the North Sea during 1992–2011, we provide evidence for a sudden increase in illegal discharges after sunset across the year. Our results show that even a tiny chance of getting caught and a mild punishment can have a major impact on behavior.
The Gulf of California (GC) is an unique large ecosystem characterized by its rich biodiversity, high biological productivity and endemism of marine life. However, as many other large ecosystems worldwide, it is subject to diverse anthropogenic pressures (overfishing, climate change, losses of biodiversity and habitats, and pollution). We reviewed over 150 studies dealing with contaminants in water, sediments and representative organisms from the GC, and here we discuss the main issues associated to the presence of metals, metalloids, persistent organic pollutants (POPs, including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), brominated diphenyl ethers (deca tri-a) (PBDEs), and several other pesticides), plastics, nutrients and algal blooms. The GC ecosystems have been subject to a wide range of pollution sources. Nevertheless, the pollution levels remain relatively low to moderate depending on the location and contaminant type. Contamination hotspots are found i) for metals and metalloids, in sites where mining spills have occurred and ii) for nutrients and pesticides, in wetlands that receive discharges from intensive agricultural and shrimp farming. We also identified sites where harmful algal blooms (HABs) have been observed. However, numerous coastal environments in GC, affected by pollution sources and events have yet been poorly studied. More detailed, extensive and comprehensive studies on the pollution levels and trends, transfer and toxic effects are still needed.
The disruption of the coral–algae symbiosis (coral bleaching) due to rising sea surface temperatures has become an unprecedented global threat to coral reefs. Despite decades of research, our ability to manage mass bleaching events remains hampered by an incomplete mechanistic understanding of the processes involved. In this study, we induced a coral bleaching phenotype in the absence of heat and light stress by adding sugars. The sugar addition resulted in coral symbiotic breakdown accompanied by a fourfold increase of coral-associated microbial nitrogen fixation. Concomitantly, increased N:P ratios by the coral host and algal symbionts suggest excess availability of nitrogen and a disruption of the nitrogen limitation within the coral holobiont. As nitrogen fixation is similarly stimulated in ocean warming scenarios, here we propose a refined coral bleaching model integrating the cascading effects of stimulated microbial nitrogen fixation. This model highlights the putative role of nitrogen-fixing microbes in coral holobiont functioning and breakdown.
Lionfish (Pterois miles) were observed avoiding coral pinnacles inhabited by the moray eels Gymnothorax flavimarginatus and G. javanicus in the northern Red Sea, Egypt. Release of lionfish (Standard Length 93–104 mm) in such coral pinnacles in November 2016 resulted in almost immediate predation by large moray eels (Total Length > 1 m). Predation by moray eels may be the key control mechanism of population growth in the native biogeographical range of Pterois spp. and may indirectly explain the success of the invasive populations. This is the first video-documented record of moray eels feeding on the lionfish P. miles.
Reef sharks may influence the foraging behaviour of mesopredatory teleosts on coral reefs via both risk effects and competitive exclusion. We used a “natural experiment” to test the hypothesis that the loss of sharks on coral reefs can influence the diet and body condition of mesopredatory fishes by comparing two remote, atoll-like reef systems, the Rowley Shoals and the Scott Reefs, in northwestern Australia. The Rowley Shoals are a marine reserve where sharks are abundant, whereas at the Scott Reefs numbers of sharks have been reduced by centuries of targeted fishing. On reefs where sharks were rare, the gut contents of five species of mesopredatory teleosts largely contained fish while on reefs with abundant sharks, the same mesopredatory species consumed a larger proportion of benthic invertebrates. These measures of diet were correlated with changes in body condition, such that the condition of mesopredatory teleosts was significantly poorer on reefs with higher shark abundance. Condition was defined as body weight, height and width for a given length and also estimated via several indices of condition. Due to the nature of natural experiments, alternative explanations cannot be discounted. However, the results were consistent with the hypothesis that loss of sharks may influence the diet and condition of mesopredators and by association, their fecundity and trophic role. Regardless of the mechanism (risk effects, competitive release, or other), our findings suggest that overfishing of sharks has the potential to trigger trophic cascades on coral reefs and that further declines in shark populations globally should be prevented to protect ecosystem health.
Coral reefs serve as natural barriers that protect adjacent shorelines from coastal hazards such as storms, waves, and erosion. Projections indicate global degradation of coral reefs due to anthropogenic impacts and climate change will cause a transition to net erosion by mid-century. Here, we provide a comprehensive assessment of the combined effect of all of the processes affecting seafloor accretion and erosion by measuring changes in seafloor elevation and volume for five coral reef ecosystems in the Atlantic, Pacific, and Caribbean over the last several decades. Regional-scale mean elevation and volume losses were observed at all five study sites and in 77 % of the 60 individual habitats that we examined across all study sites. Mean seafloor elevation losses for whole coral reef ecosystems in our study ranged from −0.09 to −0.8 m, corresponding to net volume losses ranging from 3.4 × 106 to 80.5 × 106 m3 for all study sites. Erosion of both coral-dominated substrate and non-coral substrate suggests that the current rate of carbonate production is no longer sufficient to support net accretion of coral reefs or adjacent habitats. We show that regional-scale loss of seafloor elevation and volume has accelerated the rate of relative sea level rise in these regions. Current water depths have increased to levels not predicted until near the year 2100, placing these ecosystems and nearby communities at elevated and accelerating risk to coastal hazards. Our results set a new baseline for projecting future impacts to coastal communities resulting from degradation of coral reef systems and associated losses of natural and socioeconomic resources.
The subtropical ocean gyres are recognized as great marine accummulation zones of floating plastic debris; however, the possibility of plastic accumulation at polar latitudes has been overlooked because of the lack of nearby pollution sources. In the present study, the Arctic Ocean was extensively sampled for floating plastic debris from the Tara Oceans circumpolar expedition. Although plastic debris was scarce or absent in most of the Arctic waters, it reached high concentrations (hundreds of thousands of pieces per square kilometer) in the northernmost and easternmost areas of the Greenland and Barents seas. The fragmentation and typology of the plastic suggested an abundant presence of aged debris that originated from distant sources. This hypothesis was corroborated by the relatively high ratios of marine surface plastic to local pollution sources. Surface circulation models and field data showed that the poleward branch of the Thermohaline Circulation transfers floating debris from the North Atlantic to the Greenland and Barents seas, which would be a dead end for this plastic conveyor belt. Given the limited surface transport of the plastic that accumulated here and the mechanisms acting for the downward transport, the seafloor beneath this Arctic sector is hypothesized as an important sink of plastic debris.
We investigate motivations for people's intention to contribute towards increased protection of eight threatened and endangered marine species in the United States, using factor analysis and ordered response analysis applied to data from 7425 respondents to a national household survey conducted in 2010. We find that the strength of individuals' intention to contribute towards species conservation depends on how conservation programs are funded, which species are being targeted for conservation, individuals' knowledge of and prior interaction with these species, awareness of need, awareness of responsibility, altruism, environmental concern, and contextual forces. We argue that individuals who are predisposed to contribute to conservation are likely to be incentivized by messages that focus on charismatic species and reinforce altruistic motives, and ethical beliefs. Individuals with more fiscally conservative viewpoints are more likely to respond to messages about how conservation complements their political beliefs and improves economic conditions or their quality of life.
Natural resource management agencies implement conservation policies with the presumption that they are effective and of benefit to aquatic ecosystems. However, it is often difficult to decide what management action to implement and what will be most effective. Here we call for natural resource management agencies to fully adopt and implement evidence-based management (EBM) for conservation and fisheries management. We support this call by providing a primer on systematic reviews, a core tool in evidence synthesis but one that is rarely used in the context of fisheries management. We highlight the benefits and challenges associated with implementing EBM, with a particular focus on the routine decisions and management actions undertaken by natural resource practitioners. We submit that by adopting EBM, practitioners would have access to the best available evidence on the effectiveness of various management and conservation interventions, while providing defensible and credible evidence to inform decision-making processes and policies.
The growth of marine recreational activities raises the issues of the current lack of knowledge on these activities and the information required to assess their potential impacts. Indeed, the monitoring of unrecorded activities is a great challenge, especially when basic information, such as the size of the population practicing the different activities, is unknown. In this paper, the experience of the monitoring of marine recreational fishing was used to carry out a diagnosis study to assess the cost-effectiveness of survey methods used in France between 2004 and 2012. Costs of alternative surveys were balanced with data quality, and particular attention was paid to potential biases. Results showed that the involvement of citizens through diary surveys could be a cost-effective option when the recruitment of participants complied with randomness and representativeness requirements. The outcomes of this study provide useful insights to help managers and decision makers implement monitoring schemes in similar contexts.
Marine fisheries science is a broad field that is fundamentally concerned with sustainability across ecological, economic, and social dimensions. Ensuring the delivery of food, security, equity, and well-being while sustaining ecosystems in the face of rapid change is, by far, the main challenge facing marine fisheries. A tighter integration of modeling and empiricism is needed to confront this challenge. In particular, improved incorporation of empirically grounded and realistic representation of human behaviors into models will greatly enhance our ability to predict likely outcomes under alternative adaptive strategies. Challenges to this integration certainly exist, but many of these can be overcome via improved professional training that reduces cultural rifts between empiricists and modelers and between natural and social sciences, ideally ending the presumption that there is a divide between empiricism and modeling.
Drawing on seventy-four interviews, this article analyzes the rising importance since the mid-2000s of large marine protected areas (MPAs) as a policy for managing ocean conservation. Governments have initiated eighteen large MPAs (over 200,000 km2) since 2006, reflecting the emergence of a new large MPA norm in marine conservation. This norm, we argue, emerged because of the success of a few transnational nongovernmental organizations (NGOs) in identifying politically feasible large MPAs, and then forming ad hoc domestic coalitions to lobby for them. This explanation is in contrast to most of the literature on how and why norms diffuse internationally, as well as existing explanations for the rise of large MPAs, both of which emphasize the importance of cohesive coalitions of transnational NGOs lobbying in multilateral venues. This bottom-up, international norm diffusion strategy has made large MPAs a viable policy option, one national jurisdiction at a time. For instance, this strategy was a critical element in convincing the UK to create the Pitcairn Islands Marine Reserve (835,000 km2) in 2015. Given the politics underlying the formation of large MPAs, where political gains have been high, and corporate and societal resistance relatively low, the creation of more large MPAs would seem likely, as occurred in 2016 when the UK announced it would designate three more large MPAs by 2020, totalling over 1.4 million km2. Growing support for large MPAs as a conservation strategy could also embolden states to establish large MPAs in more politically and economically contested waters, including on the Pacific high seas.