Ectotherms often attain smaller body sizes when they develop at higher temperatures. This phenomenon, known as the temperature–size rule, has important consequences for global fisheries, whereby ocean warming is predicted to result in smaller fish and reduced biomass. However, the generality of this phenomenon and the mechanisms that drive it in natural populations remain unresolved. In this study, we document the maximal size of 74 fish species along a steep temperature gradient in the Mediterranean Sea and find strong support for the temperature–size rule. Importantly, we additionally find that size reduction in active fish species is dramatically larger than for more sedentary species. As the temperature dependence of oxygen consumption depends on activity levels, these findings are consistent with the hypothesis that oxygen is a limiting factor shaping the temperature–size rule in fishes. These results suggest that ocean warming will result in a sharp, but uneven, reduction in fish size that will cause major shifts in size-dependent interactions. Moreover, warming will have major implications for fisheries as the main species targeted for harvesting will show the most substantial declines in biomass.
This article analyses the interplay between inter-State obligations to increase scientific knowledge, develop research capacity and transfer marine technology in accordance with Sustainable Development Goal (SDG) 14.a, with a view to contributing to enhanced implementation of the international law of the sea (SDG 14.c), and providing access for small-scale artisanal fishers to marine resources (SDG 14.b). It proposes to do so by relying not only on the international law of the sea, but also on international biodiversity law (particularly the Convention on Biological Diversity) and international human rights law (particularly the human right to science). The article seeks to provide a reflection on the opportunities arising from a mutually supportive interpretation of different international law instruments with regard to the means of implementation for SDG 14 in synergy with other SDGs (particularly SDG 17 on ‘Partnerships for the Goals’ and its targets related to technology transfer, capacity-building and partnerships).
With over 30 years’ experience of managing Marine Protected Areas (MPAs), China has established more than 250 MPAs in its coastal and marine areas, but the overall management effectiveness is unimpressive . Recently, China has made commitments to expand the MPA coverage in its waters ([7,52,53]) and develop an “ecological barrier” along the coast by connecting MPAs and islands by 2020 (The State Council 2015). In this context, this study reviews major challenges in current MPA practices in China, including the lack of systematic and scientific approaches, inadequate laws and regulations, ineffective governance mechanisms, conflicts between conservation and exploitation, limited funding, and inadequate monitoring programs. Four scenarios for developing China's MPA networks are developed and analyzed based on a literature review of experience in the United States, Canada, Australia, New Zealand, the European Union and the Philippines, as well as a set of interviews with Chinese MPA experts. These scenarios include: 1) creating a national system with an inventory of MPAs, 2) developing social networks, 3) developing regional ecological networks, and 4) developing a national representative network. The first two scenarios focus on the enhancement of the governance system through connecting individual MPAs as a social, institutional, and learning network, which could provide opportunities for creating an ecologically coherent network, while the latter two emphasized ecological connectivity and representativeness. Given different focuses, they can be applied at different stages of implementation and combinations of scenarios can be used depending on China's needs.
Serial depletions and the use of indiscriminate gears have led to increased fishing pressure on many previously untargeted species. A largely unregulated global extraction of seahorses (Hippocampus spp.) has emerged, of which Vietnam is one of the main sources. Quantifying this extraction is a major empirical and enforcement challenge. Using catch landings surveys of small-scale fishing boats, we determined the fishing pressure on seahorse populations around Phu Quoc Island – a major source of seahorses in Vietnam’s trade – from April to July 2014. We focused on two fishing methods, bottom trawling and compressor diving, that either targeted seahorses or caught them incidentally along with a multitude of other species. The seahorse catch consisted of three species – H. kuda, H. spinosissimus and H. trimaculatus – with relative proportions varying by gear type and fishing ground. Fishers that targeted seahorses caught mean rates of 23 and 32 seahorses per boat per day by bottom trawling and diving, respectively. Trawls and divers that did not target seahorses caught mean rates of 1 and 3 seahorses per day respectively, and caught higher proportions of juvenile seahorses. The total catch from the island was approximately 127,000–269,000 seahorses per year from a fleet of 124 trawl boats and 46 compressor diver vessels. This is up to four times higher than the catch of similarly sized fisheries that obtain seahorses and is likely placing high pressure on local seahorse populations. Our research emphasizes the need to monitor these fisheries and develop effective management efforts for sustainable seahorse populations.
Maritime Spatial Planning (hereinafter mentioned as MSP) is developing and growing rapidly and constantly worldwide. It is acknowledged as a key instrument to balance sectoral interests and achieve sustainable use of marine resources with the ecosystem-based approach as the underpinning principle (EC, 2010). Nevertheless, there are different planning approaches and different levels of implementation of maritime/marine spatial planning (MSP) processes in the world. Among the plans implemented in Europe, and based on the planning processes developed, different aims for MSP can be noted which translate into either strategic, fully integrated, forward-looking and participative planning or “spatial optimization” elements. On the other hand there are areas where MSP is in an immature phase and where mutual learning, improved governance or capacity building is needed, or areas where a strategic approach to facilitate coordination of MSP arrangements would be necessary. This paper addresses current MSP attitudes, challenges and future trends and discusses the MSP planning and management conceptual approaches, options and styles, mainly as defined through the European regulatory framework.
Many fishers diversify their income by participating in multiple fisheries, which has been shown to significantly reduce year-to-year variation in income. The ability of fishers to diversify has become increasingly constrained in the last few decades, and catch share programs could further reduce diversification as a result of consolidation. This could increase income variation and thus financial risk. However, catch shares can also offer fishers opportunities to enter or increase participation in catch share fisheries by purchasing or leasing quota. Thus, the net effect on diversification is uncertain. We tested whether diversification and variation in fishing revenues changed after implementation of catch shares for 6,782 vessels in 13 US fisheries that account for 20% of US landings revenue. For each of these fisheries, we tested whether diversification levels, trends, and variation in fishing revenues changed after implementation of catch shares, both for fishers that remained in the catch share fishery and for those that exited but remained active in other fisheries. We found that diversification for both groups was nearly always reduced. However, in most cases, we found no significant change in interannual variation of revenues, and, where changes were significant, variation decreased nearly as often as it increased.
The rates of marine deoxygenation leading to Cretaceous Oceanic Anoxic Events are poorly recognized and constrained. If increases in primary productivity are the primary driver of these episodes, progressive oxygen loss from global waters should predate enhanced carbon burial in underlying sediments—the diagnostic Oceanic Anoxic Event relic. Thallium isotope analysis of organic-rich black shales from Demerara Rise across Oceanic Anoxic Event 2 reveals evidence of expanded sediment-water interface deoxygenation ~43 ± 11 thousand years before the globally recognized carbon cycle perturbation. This evidence for rapid oxygen loss leading to an extreme ancient climatic event has timely implications for the modern ocean, which is already experiencing large-scale deoxygenation.
Plastic pollution is an anthropogenic stressor in marine ecosystems globally. Many species of marine fish (more than 50) ingest plastic debris. Ingested plastic has a variety of lethal and sublethal impacts and can be a route for bioaccumulation of toxic compounds throughout the food web. Despite its pervasiveness and severity, our mechanistic understanding of this maladaptive foraging behaviour is incomplete. Recent evidence suggests that the chemical signature of plastic debris may explain why certain species are predisposed to mistaking plastic for food. Anchovy (Engraulis sp.) are abundant forage fish in coastal upwelling systems and a critical prey resource for top predators. Anchovy ingest plastic in natural conditions, though the mechanism they use to misidentify plastic as prey is unknown. Here, we presented wild-caught schools of northern anchovy (Engraulis mordax) with odour solutions made of plastic debris and clean plastic to compare school-wide aggregation and rheotactic responses relative to food and food odour presentations. Anchovy schools responded to plastic debris odour with increased aggregation and reduced rheotaxis. These results were similar to the effects food and food odour presentations had on schools. Conversely, these behavioural responses were absent in clean plastic and control treatments. To our knowledge, this is the first experimental evidence that adult anchovy use odours to forage. We conclude that the chemical signature plastic debris acquires in the photic zone can induce foraging behaviours in anchovy schools. These findings provide further support for a chemosensory mechanism underlying plastic consumption by marine wildlife. Given the trophic position of forage fish, these findings have considerable implications for aquatic food webs and possibly human health.
Marine debris, mostly consisting of plastic, is a global problem, negatively impacting wildlife, tourism and shipping. However, despite the durability of plastic, and the exponential increase in its production, monitoring data show limited evidence of concomitant increasing concentrations in marine habitats. There appears to be a considerable proportion of the manufactured plastic that is unaccounted for in surveys tracking the fate of environmental plastics. Even the discovery of widespread accumulation of microscopic fragments (microplastics) in oceanic gyres and shallow water sediments is unable to explain the missing fraction. Here, we show that deep-sea sediments are a likely sink for microplastics. Microplastic, in the form of fibres, was up to four orders of magnitude more abundant (per unit volume) in deep-sea sediments from the Atlantic Ocean, Mediterranean Sea and Indian Ocean than in contaminated sea-surface waters. Our results show evidence for a large and hitherto unknown repository of microplastics. The dominance of microfibres points to a previously underreported and unsampled plastic fraction. Given the vastness of the deep sea and the prevalence of microplastics at all sites we investigated, the deep-sea floor appears to provide an answer to the question—where is all the plastic?
The purpose of this paper is to analyse the relationship of the proposed new UNCLOS Implementing Agreement concerning the conservation and sustainable use of marine biological diversity of areas beyond national jurisdiction with the current legal framework concerning fisheries. It elaborates on selected elements that are under negotiations, namely: marine genetic resources, area-based management tools, including marine protected areas, as well as environmental impact assessments. Each of those elements is analyzed with particular emphasis being laid on the following issues. Firstly, how the current legal status quo in the relevant area looks like. Secondly, how the question of fisheries could be included in a future treaty and, thirdly, what bearing it could have on the current framework of the management of fisheries.
The article concludes with the identification of possible fields where the new treaty could bring added value. However, some possible challenges are mentioned as well. They relate in particular to the fact that the mandate of negotiations underscores that they shall not ‘undermine existing legal instruments and frameworks and relevant global, regional and sectoral bodies’.
Scholars of political ecology have long been interested in questions of access, equity, and power in environmental management. This paper explores these domains by examining lived experiences and daily realities in Iceland’s fishing communities, 30 years after the implementation of a national privatized Individual Transferrable Quota (ITQ) fisheries management system. Drawing upon ethnographic data collected over 2 years in the rural coastal communities of Northwest Iceland, we address three questions; 1) How the ITQ system relates to other complex social and environmental factors facing coastal communities today. 2) How attempts to alleviate negative impacts of the ITQ system have led to new rifts in communities and 3) how the decision-making power of a few dominant interest groups in national politics leaves small-boat fishermen and rural communities at a disadvantage. In the words of our study participants, the Icelandic fisheries management scheme has created “little kings” in rural communities, where each little king acts in his own best interest, yet has no recourse to collective power and no platform to influence national politics. In this volatile political situation with cross-scale implications, it is difficult for fishermen, their families, and community members to imagine ways in which power over and access to the fisheries resource can be redistributed.
Fish substitution and fish fraud are widely observed on the global food market. To detect and prevent substitution, DNA-based methods do not always meet the demand of being time- and cost-efficient; therefore, methodology improvements are needed. The use of species-specific protein patterns, as determined by matrix-assisted laser desorption/ ionization time-of-flight (MALDI-TOF) mass spectrometry has recently improved species identification of prokaryotes, both time- and cost-wise. We have used the method to establish a database containing protein patterns of common food fish prone to substitution. The database currently comprises 54 fish species. Aspects such as the sensitivity of identification on species level and the impact of bacterial contamination of fish filet are assessed. Most database entries are characterized by low intraspecies but high interspecies variability. Hitherto, 118 validation samples were successfully determined. The herein presented results underline the potential and reliability of eukaryotic species identification via MALDI-TOF mass spectrometry.
As the summer minimum in Arctic sea ice cover reduces in area year by year due to anthropogenic global climate change, so interest grows in the un-tapped oil, gas and fisheries resources that were previously concealed beneath. We show that existing marine protected areas in the Arctic Ocean offer little or no protection to many habitats and deep seafloor features that coincide spatially with areas likely to be of interest to industry. These habitats are globally unique, hosting Arctic species within pristine environments that are currently undergoing rapid adjustment to climate-induced changes in ocean dynamics, species migration and primary production. They are invaluable as reference points for conservation monitoring and assessment. The existing Arctic marine protected area network needs to be expanded in order to protect these habitats and be fully coordinated with other spatial and non-spatial measures intended to protect Arctic habitats and ensure any uses of Arctic marine or subsea resources are sustainable.
The Natura 2000 network forms the cornerstone of the biodiversity conservation strategy of the European Union and is the largest coordinated network of protected areas (PAs) in the world. Here, we demonstrated that the network fails to adequately cover the marine environment and meet the conservation target of 10% set by the Convention on Biological Diversity. The relative percentage of marine surface cover varies significantly among member states. Interestingly, the relative cover of protected seascape was significantly lower for member states with larger exclusive economic zones. Our analyses demonstrated that the vast majority (93%) of the Natura 2000 sites that cover marine waters include both a terrestrial and a marine component. As a result, the majority of the protected surfaces is adjacent to the coastline, and decreases offshore; only 20% of Natura marine PAs is at depths >200 m. The lack of systematic planning processes is further reflected by the great variability in the distances among protected sites and the limited number of shared Natura sites among member states. Moreover, <40% of the marine sites have management plans, indicating the absence of active, or limited management in most sites. This work highlights the gaps in coverage and spatial design of the European conservation network in the marine environment, and raises questions on the unevenly treatment of marine vs. terrestrial areas.
Given competing objectives vying for space in the marine environment, the island of Bermuda may be an ideal candidate for comprehensive marine spatial planning (MSP). However, faced with other pressing issues, ocean management reform has not yet received significant traction from the government, a pattern seen in many locations. Spatial planning processes often struggle during the proposal, planning, or implementation phases due to stakeholder opposition and/or government wariness to change. Conflict among stakeholders about management reform has also proven to be a deterrent to MSP application in many locations. With these obstacles in mind, a detailed stakeholder survey was conducted in Bermuda to determine awareness, attitudes and perceptions regarding ocean health, threats to ocean environments, the effectiveness of current ocean management, and possible future changes to management. How perceptions vary for different types of stakeholders and how attitudes about specific concerns relate to attitudes about management changes were examined. Overall, the results indicate a high degree of support for spatial planning and ocean zoning and a high level of concordance even among stakeholder groups that are typically assumed to have conflicting agendas. However, attitudes were not entirely homogeneous, particularly when delving into details about specific management changes. For example, commercial fishers were generally less in favor, relative to other stakeholder groups, of increasing regulations on ocean uses with the notable exception of regulations for recreational fishing. Given the results of this survey, public support is likely to be high for government action focused on ocean management reform in Bermuda.
The creation of Marine Protected Areas (MPAs) and MPA networks is increasing globally. This trend is reflected in England's waters, where 34.7% of waters are protected. MPA network creation can displace activities (primarily fisheries) that are thought to be incompatible with the habitats and species of conservation importance that the network has been established to protect. There is also an obligation on the UK Government to ensure that all of its waters achieve Good Environmental Status (GES) by 2020 under the Marine Strategy Framework Directive. The designation of MPAs and the subsequent introduction of management measures that displace activities may result in unintended impacts/consequences on protected benthic habitats or species within (a) the MPA where management measures have been introduced, (b) other MPAs or (c) wider UK or international waters. An incomplete understanding of the extent and type of fishing that is occurring within the MPA network (and throughout English waters in general), coupled with a paucity of information regarding how fishing effort is displaced as a result of MPA designation, may hinder the achievement of both GES by 2020 and MPA management goals. Better understanding of fishing effort displacement can inform the siting of future MPAs, aid marine spatial planning and improve existing MPA management. To aid the better description and understanding of the various facets of fisheries effort displacement, this paper proposes for the first time a structure to differentiate the types of fisheries displacement. Measures to mitigate the consequences of displaced fishing effort are also identified.
Small cetaceans (dolphins and porpoises) face serious anthropogenic threats in coastal habitats. These include bycatch in fisheries; exposure to noise, plastic and chemical pollution; disturbance from boaters; and climate change. Generating reliable abundance estimates is essential to assess sustainability of bycatch in fishing gear or any other form of anthropogenic removals and to design conservation and recovery plans for endangered species. Cetacean abundance estimates are lacking from many coastal waters of many developing countries. Lack of funding and training opportunities makes it difficult to fill in data gaps. Even if international funding were found for surveys in developing countries, building local capacity would be necessary to sustain efforts over time to detect trends and monitor biodiversity loss. Large-scale, shipboard surveys can cost tens of thousands of US dollars each day. We focus on methods to generate preliminary abundance estimates from low-cost, small-boat surveys that embrace a ‘training-while-doing’ approach to fill in data gaps while simultaneously building regional capacity for data collection. Our toolkit offers practical guidance on simple design and field data collection protocols that work with small boats and small budgets, but expect analysis to involve collaboration with a quantitative ecologist or statistician. Our audience includes independent scientists, government conservation agencies, NGOs and indigenous coastal communities, with a primary focus on fisheries bycatch. We apply our Animal Counting Toolkit to a small-boat survey in Canada’s Pacific coastal waters to illustrate the key steps in collecting line transect survey data used to estimate and monitor marine mammal abundance.
This research explores whether millennials’ interest in plastic pollution, ocean trash, and debris can be an entry point to engagement on other ocean conservation issues. The research found that, for millennials, plastic in the ocean has traction as a top pollution concern. This generation believes we can make progress and find compelling solutions through personal actions and the work of conservation groups.
Estuaries are threatened by intense and continuously increasing human activities. Here we estimated the sensitivity of fish assemblages in a set of estuaries distributed worldwide (based on species vulnerability and resilience), and the exposure to cumulative stressors and coverage by protected areas in and around those estuaries (from marine, estuarine and freshwater ecosystems, due to their connectivity). Vulnerability and resilience of estuarine fish assemblages were not evenly distributed globally and were driven by environmental features. Exposure to pressures and extent of protection were also not evenly distributed worldwide. Assemblages with more vulnerable and less resilient species were associated with estuaries in higher latitudes (in particular Europe), and with higher connectivity with the marine ecosystem, moreover such estuaries were generally under high intensity of pressures but with no concomitant increase in protection. Current conservation schemes pay little attention to species traits, despite their role in maintaining ecosystem functioning and stability. Results emphasize that conservation is weakly related with the global distribution of sensitive fish species in sampled estuaries, and this shortcoming is aggravated by their association with highly pressured locations, which appeals for changes in the global conservation strategy (namely towards estuaries in temperate regions and highly connected with marine ecosystems).
Government-managed marine protected areas (MPAs) can restore small fish stocks, but have been heavily criticized for excluding resource users and creating conflicts. A promising but less studied alternative are community-managed MPAs, where resource users are more involved in MPA design, implementation and enforcement. Here we evaluated effects of government- and community-managed MPAs on the density, size and biomass of seagrass- and coral reef-associated fish, using field surveys in Kenyan coastal lagoons. We also assessed protection effects on the potential monetary value of fish; a variable that increases non-linearly with fish body mass and is particularly important from a fishery perspective. We found that two recently established community MPAs (< 1 km2 in size, ≤ 5 years of protection) harbored larger fish and greater total fish biomass than two fished (open access) areas, in both seagrass beds and coral reefs. As expected, protection effects were considerably stronger in the older and larger government MPAs. Importantly, across management and habitat types, the protection effect on the potential monetary value of the fish was much stronger than the effects on fish biomass and size (6.7 vs. 2.6 and 1.3 times higher value in community MPAs than in fished areas, respectively). This strong effect on potential value was partly explained by presence of larger (and therefore more valuable) individual fish, and partly by higher densities of high-value taxa (e.g. rabbitfish). In summary, we show that i) small and recently established community-managed MPAs can, just like larger and older government-managed MPAs, play an important role for local conservation of high-value fish, and that ii) these effects are equally strong in coral reefs as in seagrass beds; an important habitat too rarely included in formal management. Consequently, community-managed MPAs could benefit both coral reef and seagrass ecosystems and provide spillover of valuable fish to nearby fisheries.