The sustainable management of flats fishing requires establishing limits on the number of boats as its demand continues to grow. This study integrated different techniques to determine the carrying capacity in a recreational fishery: optimum boating density, visual fish census, geographic information system, fishing guides interviews and decision theory. The optimum boating density was based on the effective fishing area (EFA) and on the optimum density. The EFA represented 36% of the bay and was calculated from 53 fishing trips tracked with GPS data loggers. The data were analyzed in a geographic information system that incorporated the effect of the winds on the fish behavior. The maximum number of boats was calculated under four scenarios: northern winds, eastern winds, south-eastern winds and calm winds. The optimum density (average = 1.2 Km2, SD = 0.5) was obtained from anglers' statements. The decision theory results showed that the maximum number of boats under wind variability could be up to 89 boats in the fishery.
Ice arches in the Canadian Arctic Archipelago (CAA) block the inflow of Arctic Ocean ice for the majority of the year. A 22‐year record (1997‐2018) of Arctic Ocean‐CAA ice exchange was used to investigate the effect of warming on CAA sea ice dynamics. Larger ice area flux values were associated with longer flow duration and faster ice speed facilitated by increased open water leeway from the CAA's transition to a younger and thinner ice regime, that together have contributed to a significant ice area flux increase (103 km2/year) from Arctic Ocean into the northern CAA from 1997‐2018. Remarkably, the 2016 Arctic Ocean ice area flux into the CAA (161x103 km2) was 7 times greater than the 1997‐2018 average (23x103 km2) and almost double the 2007 ice area flux into Nares Strait (87x103 km2). Continued warming may result in the CAA becoming a larger outlet for Arctic Ocean ice area loss.
The Protocol on Environmental Protection of the Antarctic Treaty stipulates that the protection of the Antarctic environment and associated ecosystems be fundamentally considered in the planning and conducting of all activities in the Antarctic Treaty area. One of the key pollutants created by human activities in the Antarctic is noise, which is primarily caused by ship traffic (from tourism, fisheries, and research), but also by geophysical research (e.g., seismic surveys) and by research station support activities (including construction). Arguably, amongst the species most vulnerable to noise are marine mammals since they specialize in using sound for communication, navigation and foraging, and therefore have evolved the highest auditory sensitivity among marine organisms. Reported effects of noise on marine mammals in lower-latitude oceans include stress, behavioral changes such as avoidance, auditory masking, hearing threshold shifts, and—in extreme cases—death. Eight mysticete species, 10 odontocete species, and six pinniped species occur south of 60°S (i.e., in the Southern or Antarctic Ocean). For many of these, the Southern Ocean is a key area for foraging and reproduction. Yet, little is known about how these species are affected by noise. We review the current prevalence of anthropogenic noise and the distribution of marine mammals in the Southern Ocean, and the current research gaps that prevent us from accurately assessing noise impacts on Antarctic marine mammals. A questionnaire given to 29 international experts on marine mammals revealed a variety of research needs. Those that received the highest rankings were (1) improved data on abundance and distribution of Antarctic marine mammals, (2) hearing data for Antarctic marine mammals, in particular a mysticete audiogram, and (3) an assessment of the effectiveness of various noise mitigation options. The management need with the highest score was a refinement of noise exposure criteria. Environmental evaluations are a requirement before conducting activities in the Antarctic. Because of a lack of scientific data on impacts, requirements and noise thresholds often vary between countries that conduct these evaluations, leading to different standards across countries. Addressing the identified research needs will help to implement informed and reasonable thresholds for noise production in the Antarctic and help to protect the Antarctic environment.
The accumulation patterns of floating marine litter (FML) in the Black Sea and the stranding locations on coasts are studied by performing dedicated Lagrangian simulations using freely available ocean current and Stokes drift data from operational models. The low FML concentrations in the eastern and northern areas and the high concentrations along the western and southern coasts are due to the dominant northerlies and resulting Ekman and Stokes drift. No pronounced FML accumulation zones resembling the Great Pacific Garbage Patch are observed at time scales from months to a year. The ratio of circulation intensity (measured by the sea level slope) to the rate of the temporal variability of sea level determines whether FML will compact. This ratio is low in the Black Sea, which is prohibitive for FML accumulation. It is demonstrated that the strong temporal variability of the velocity field (ageostrophic motion) acts as a mixing mechanism that opposes another ageostrophic constituent of the velocity field (spatial variability in sea level slope, or frontogenesis), the latter promoting the accumulation of particles. The conclusion is that not all ageostrophic ocean processes lead to clustering. The short characteristic stranding time of ∼20 days in this small and almost enclosed basin explains the large variability in the total amount of FML and the low FML concentration in the open ocean. The predominant stranding areas are determined by the cyclonic general circulation. The simulated distribution of stranded objects is supported by available coastal and near-coastal observations. It is shown that the areas that were the most at risk extend from the Kerch Strait to the western coast.
Worldwide fisheries management has been undergoing a paradigm shift from a single-species approach to ecosystem approaches. In the United States, NOAA has adopted a policy statement and Road Map to guide the development and implementation of ecosystem-based fisheries management (EBFM). NOAA’s EBFM policy supports addressing the ecosystem interconnections to help maintain resilient and productive ecosystems, even as they respond to climate, habitat, ecological, and social and economic changes. Managing natural marine resources while taking into account their interactions with their environment and our human interactions with our resources and environment requires the support of ecosystem science, modeling, and analysis. Implementing EBFM will require using existing mandates and approaches that fit regional management structures and cultures. The primary mandate for managing marine fisheries in the United States is the Magnuson-Stevens Fishery Conservation and Management Act. Many tenets of the Act align well with the EBFM policy, however, incorporating ecosystem analysis and models into fisheries management processes has faced procedural challenges in many jurisdictions. In this paper, we review example cases where scientists have had success in using ecosystem analysis and modeling to inform management priorities, and identify practices that help bring new ecosystem science information into existing policy processes. A key to these successes is regular communication and collaborative discourse among modelers, stakeholders, and resource managers to tailor models and ensure they addressed the management needs as directly as possible.
Snapper and grouper are important fisheries resources, with high commercial value and an important role in the livelihoods and food security of many local communities worldwide. However, the status of many snapper and grouper fisheries is unknown, particularly in the cases of small-scale fisheries in developing countries. The main goals of this work are to provide an overview of the current status and trends of these resources and to find alternative sources of information that could be used to determine the status of snapper and grouper fisheries, as well as other data-limited fisheries. Several complementary approaches were explored, including determination of the status of snapper and grouper fisheries based on FAO assessment criteria, analysis of landings time-series trends, and investigation of whether other variables could be used as proxies for fishery status. About half of these fisheries were classified as overexploited, 30% as non-fully exploited and 19% as fully exploited. The FAO landings data indicated that the number of overexploited fisheries has been increasing over the years and that the majority of these fisheries are in transition between the fully exploited and overexploited statuses. The Human Development Index emerged as a potential proxy for the status of the biomass. The multinomial modeling approach explained about 44% of the variability observed in the biomass stock status classification data and indicated a high level of correspondence between original and estimated status, which makes this approach very attractive for application to other data-limited fisheries.
The increasing use of tracking devices, such as the Vessel Monitoring System (VMS) and the Automatic Identification System (AIS), have allowed, in the last decade, detailed spatial and temporal analyses of fishing footprints and of their effects on environments and resources. Nevertheless, tracking devices usually allow monitoring of the largest length classes composing different fleets, whereas fishing vessels below a regulatory threshold (i.e., 15 m in length-over-all) are not mandatorily equipped with these tools. This issue is critical, since 36% of the vessels in the European Union (EU) fleets belong to these “hidden” length classes. In this study, a model [namely, a cascaded multilayer perceptron network (CMPN)] is devised to predict the annual fishing footprints of vessels without tracking devices. This model uses information about fleet structures, environmental characteristics, human activities, and fishing effort patterns of vessels equipped with tracking devices. Furthermore, the model is able to take into account the interactions between different components of the fleets (e.g., fleet segments), which are characterized by different operating ranges and compete for the same marine space. The model shows good predictive performance and allows the extension of spatial analyses of fishing footprints to the relevant, although still unexplored, fleet segments.
Marine reserves are an important management tool for conserving local biodiversity and protecting fragile ecosystems such as seagrass that provide significant ecological functions and services to people and the marine environment. With humans placing ever-growing pressure on seagrass habitats, marine reserves also provide an important reference from which changes to seagrass and their ecological assemblages may be assessed. After eight years of protection of seagrass beds (Posidonia australis) in no-take marine reserves (Sanctuary Zones) within the Jervis Bay Marine Park (New South Wales, Australia; zoned in 2002), we aimed to assess what changes may have occurred and assess continuing change through time in fish assemblages within these seagrass meadows. Using baited remote underwater videos (BRUVs), we sampled seagrass fish assemblages at three locations in no-take zones and five locations in fished zones three times from 2010 to 2013. Overall, we observed a total of 2615 individuals from 40 fish species drawn from 24 families. We detected no differences in total fish abundance, diversity, or assemblage composition between management zones, although we observed a significant increase in Haletta semifasciata, a locally targeted fish species, in no-take marine reserves compared with fished areas. Fish assemblages in seagrass varied greatly amongst times and locations. Several species varied in relative abundance greatly over months and years, whilst others had consistently greater relative abundances at specific locations. We discuss the potential utility of marine reserves covering seagrass habitats and the value of baseline data from which future changes to seagrass fish populations may be measured.
Marine protected areas (MPAs) have emerged as a valuable tool in biodiversity conservation and fisheries management. However, the effective use of MPAs depends upon the successful integration of social and ecological information. We investigated relationships between the social system structure of coastal communities alongside biological data describing the status and trends in fish communities around Yap, Micronesia. Traditional marine tenure made Yap an ideal place to investigate the underlying principles of social-ecological systems, as communities own and manage spatially-defined coastal resources. Analysis of social survey data revealed three social regimes, which were linked to corresponding gradients of ecological outcomes. Communities with decentralized decision-making and a preference for communal forms of fishing had the greatest ecological outcomes, while communities lacking any form of leadership were linked to poor ecological outcomes. Interestingly, communities with strong top-down leadership were shown to have variable ecological outcomes, depending on the presence of key groups or individuals. We last investigated whether social perception could successfully predict the status of fish assemblages within non-managed reefs. Several biological metrics of fish assemblages within non-managed areas were significantly predicted by a gradient of human access, suggesting social perception could not predict the growing human footprint over the study period. These findings highlight the potentially overlooked role that community-oriented decision-making structures and fishing methods could play in successful conservation efforts, and the limitations of perception data. Policies that promote communal marine resource use offer a novel approach to improve fisheries management and promote social-ecological resilience.
An assessment of quantity, composition and seasonal variation of fishing-related plastic debris was conducted in six beaches along the Kerala coast of India during 2017–2018. Plastic items were the most dominant type of waste constituting 73.8% by number and 59.9% by weight. In the total debris recorded, 5540 pieces (36%) weighing 198.4 kg (39.8%) were fishing related trash. On an average 14.4 ± 12 fishing related items/100 m2, corresponding to mean weight of 0.55 ± 0.7 kg/100 m2 was recorded from these beaches. Results indicated that the fishing-related plastic items were concentrated four times more in the beaches with higher fishing intensity, as compared to the other beaches. Also, the concentration of fishing-related plastic was recorded higher in the post-monsoon season compared to the lowest during monsoon, which was significant with p-value < 0.05. The results emphasize the role of fishing activities in the generation of marine litter.
Following the Editorial addressing the BALMAS project, we open the ballast water management special issue for the Adriatic Sea by providing background information on non-indigenous species and the mechanisms (vectors) of transport. Problems allocating introduction mechanisms for various species with certainty are described; in general, key introduction mechanisms are shipping, with ballast water and biofouling as dominant vectors, and aquaculture activities. The dominant mechanisms for introduction may differ through time, between regions and across species. We highlight ballast water as the focus of an international convention to prevent future introductions, reviewing management options and suggesting future research needs. This assessment is not restricted in application to the Adriatic Sea, but is applicable to other coastal waters. Results of such future work may contribute to the experience building phase planned by the International Maritime Organization for a harmonised implementation of the Ballast Water Management Convention.
The fossil record provides valuable data for improving our understanding of both past and future reef resilience and vulnerability to environmental change. The spatial and temporal pattern of the initiation of the Holocene Great Barrier Reef presents a case study of reef response to rapid sea-level rise. Past studies have been limited by the lack of well-dated and closely spaced reef core transects and have not closely examined the composition of the reef-building communities through time. This study presents 80 new high precision U-Th and 5 radiocarbon ages from twelve new cores located along three transects across different geomorphic and hydrodynamic settings of One Tree Reef, southern Great Barrier Reef, to document three distinct stages of Holocene reef development in unprecedented detail. Temporal constraints on changing paleoecological assemblages of coral, coralline algae and associated biota revealed three distinct phases of reef development, consisting of: 1) a fast, shallow and clear-water reef initiation from 8.3 until 8 ka; 2) a shift to slower, deeper and more turbid-water reef growth from 8-7 ka; and 3) a return to shallow and rapid branching coral growth in clear-water conditions as the reef “catches up” to sea-level. A minimum lag prior to reef initiation of 700 years was identified, which differs in length depending on reef environment and Pleistocene substrate height. In this new model, reef growth initiated on the topographically lower leeward margin and patch reef, prior to the start of windward margin development, contrary to the traditional reef growth model. While there was a shift to conditions less favorable for reef growth at 8 ka, this did not prevent the slow accretion of more sediment-tolerant coral communities. The majority of the reef reached sea level by ~6 ka. This new conceptual model of Holocene reef growth provides new constraints on changes in paleoenvironment that controlled reef community composition and growth trajectories through sea-level rise following inundation.
Microplastics (MPs, particles <5 mm) represent an emerging global environmental concern, having been detected in multiple aquatic species. However, very little is known about the presence of MPs in higher trophic level species, including cetaceans. We worked with community based monitors and Inuvialuit hunters from Tuktoyaktuk (Northwest Territories, Canada) to sample seven beluga whales (Delphinapterus leucas) in 2017 and 2018. Microplastics were detected in the gastrointestinal tracts in every whale. We estimate that each whale contained 18 to 147 MPs in their GI tract (average of 97 ± 42 per individual). FTIR-spectroscopy revealed over eight plastic polymer types, with nearly half being polyester. Fibres made up 49% of MPs. The diversity of MP shapes and polymeric identities in beluga points to a complex source scenario, and ultimately raises questions regarding the significance and long-term exposure of this pollutant in this ecologically and culturally valuable species.
Microplastics (MP) pollution has received increased attention over the last few years. However, while the number of studies documentating the ingestion of microplastics by fish has increased, fewer studies have addressed the toxicological effects derived from the ingestion of these small items in wild conditions. Here, MP contamination and effect biomarkers were investigated in three commercially important fish species from North East Atlantic Ocean. From the 150 analysed fish (50 per species), 49 % had MP. In fish from the 3 species, MP in the gastrointestinal tract, gills and dorsal muscle were found. Fish with MP had significantly (p ≤ 0.05) higher lipid peroxidation levels in the brain, gills and dorsal muscle, and increased brain acetylcholinesterase activity than fish where no MP were found. These results suggest lipid oxidative damage in gills and muscle, and neurotoxicity through lipid oxidative damage and acetylcholinesterase induction in relation to MP and/or MP-associated chemicals exposure. From the 150 fish analysed, 32 % had MP in dorsal muscle, with a total mean (± SD) of 0.054 ± 0.099 MP items/g. Based on this mean and on EFSA recommendation for fish consumption by adults or the general population, human consumers of Dicentrachus labrax, Trachurus trachurus, Scomber colias may intake 842 MP items/year from fish consumption only. Based on the mean of MP in fish muscle and data (EUMOFA, NOAA) of fish consumption per capita in selected European and American countries, the estimated intake of microplastics through fish consumption ranged from 518 to 3078 MP items/year/capita. Considering that fish consumption is only one of the routes of human exposure to microplastics, this study and others in the literature emphasize the need for more research, risk assessment and adoption of measures to minimize human exposure to these particles. Thus, microplastics pollution and its effects should be further investigated and addressed according to the WHO ‘One Health’ approach.
Significant quantities of plastic debris pollute nearly all the world’s ecosystems, where it persists for decades and poses a considerable threat to flora and fauna. Much of the focus has been on the marine environment, with little information on the hazard posed by debris accumulating on beaches and adjacent vegetated areas. Here we investigate the potential for beach debris to disrupt terrestrial species and ecosystems on two remote islands. The significant quantities of debris on the beaches, and throughout the coastal vegetation, create a significant barrier which strawberry hermit crabs (Coenobita perlatus) encounter during their daily activities. Around 61,000 (2.447 crabs/m2) and 508,000 crabs (1.117 crabs/m2) are estimated to become entrapped in debris and die each year on Henderson Island and the Cocos (Keeling) Islands, respectively. Globally, there is an urgent need to establish a clear link between debris interactions and population persistence, as loss of biodiversity contributes to ecosystem degradation. Our findings show accumulating debris on these islands has the potential to seriously impact hermit crab populations. This is important for countless other islands worldwide where crabs and debris overlap, as crabs play a crucial role in the maintenance of tropical ecosystems.
Using simple models, coupled with parameters extracted from published studies, the annual inputs of macro and micro plastics to the Scottish Atlantic Coast and the Scottish North Sea Coast regions are estimated. Two estimates of land-based sources are used, scaled by catchment area population size. The oceanic supply of floating plastic is estimated for wind-driven and general circulation sources. Minimum, typical and maximum values are computed to examine the magnitude of uncertainties. Direct inputs from fishing and the flux of macroplastic onto the seabed are also included. The modelled estimates reveal the importance of local litter sources to Scottish coastal regions, and hence local management actions can be effective. Estimates provide a scale against which removal efforts may be compared, and provide input data for future more complex modelling. Recommendations for research to improve the preliminary estimates are provided. Methods presented here may be useful elsewhere.
The scientific literature on marine and coastal climate change has proliferated in recent decades. Translating and communicating this evidence in a timely, and accessible manner, is critical to support adaptation, but little is being done to summarise the latest science for decision makers. For Small Island Developing States (SIDS), which are highly vulnerable to marine and coastal climate change impacts, there is an urgent need to make the latest science readily available to inform national policy, leverage climate funding and highlight their vulnerability for international reports and climate negotiations. Climate change report cards are a proven successful way of presenting climate change information in an easily accessible and informative manner. Here we compare the development of marine climate change report cards for Caribbean and Pacific Commonwealth SIDS as a means of translating the latest science for decision makers. Regional engagement, priority issues and lessons learnt in these regions are compared, and future opportunities identified.
This study explored public perceptions of the marine environment in three coastal communities in Greece and further investigated intentions to adopt behaviors that contribute to marine conservation. We used the Theory of Planned Behavior (TPB) to study the psychological determinants of behavioral intentions. The findings indicated that respondents have positive attitudes, moderate knowledge of marine issues, and they value the marine environment for the multiple ecosystem services that it provides. Litter and pollution from industry were considered as the most important marine threats, followed by fishing and farming. Participants suggested that informing the public and giving prominence to environmental education can contribute to marine conservation efforts. They felt that research centers and scientific community were more competent than governmental authorities and the private sector concerning the management and protection of the marine environment. Intention to adopt environmental behaviors was influenced by normative considerations, attitudes toward marine biodiversity and perceived behavioral control beliefs. The results may: 1) help inform policymakers to improve marine resource management towards a more sustainable relationship between people and the sea; 2) support the development of marine strategies that fit the social preferences, needs, and priorities to increase the likelihood of public support; and 3) support marine spatial planning efforts to uncover the intrinsic complexity of societal interactions with the marine environment. The findings further support policymakers that wish to promote behavior change through communication strategies that deliver environmental messages that focus on enhancing normative considerations, behavioral control beliefs, and corresponding attitudes.
Commercial fisheries yield essential foods, sustain cultural practices, and provide widespread employment around the globe. Commercially harvested species face a myriad of anthropogenic threats including degraded habitats, changing climate, overharvest, and pollution. Microplastics are pollutants of increasing concern, which are pervasive in the environment and can harbor or adsorb pollutants from surrounding waters. Aquatic organisms, including commercial species, encounter and ingest microplastics, but there is a paucity of data about those caught and cultured in North America. Additional research is needed to determine prevalence, physiological effects, and population‐level implications of microplastics in commercial species from Canada, the United States, and Mexico. Investigations into possible human health effects of microplastic exposure from seafood are also greatly needed. This synthesis summarizes current knowledge, identifies data gaps, and provides future research directions for addressing microplastics effects in commercially valuable North American fishery species.