To assess fishing effects on data-poor species, impact can be derived from spatial overlap between species distribution and fishing effort and gear catchability. Here, we enhance the existing sustainability assessment for fishing effect method by estimating gear efficiency and heterogeneous density from sporadic catch data. We apply the method to two chondrichthyan bycatch species, Bight Skate and Draughtboard Shark in Australia, to assess cumulative fishing mortality (Fcum) from multiple fisheries. Gear efficiency is estimated from a Bayesian mixture distribution model and fish density is predicted by a generalized additive model. These results, combined with actual fishing effort, allow estimation of fishing mortality in each sector and subsequently, the Fcum. Risk is quantified by comparing Fcum with reference points based on life history parameters. When only the point estimates were considered, our result indicates that for the period 2009 and 2010 Bight Skate caught in 14 fisheries was at high cumulative risk (Fcum ≥ Flim) while Draughtboard Shark caught by 19 fisheries was at low cumulative risk (Fcum ≤ Fmsy). Because of the high cost of conducting cumulative risk assessments, we recommend examining the distribution of fishing effort across fisheries before carrying out the assessments.
Whales are federally protected by the Marine Mammal Protection Act; endangered species, such as the North Atlantic right whale, receive additional protection under the Endangered Species Act. However, their regulations have failed to satisfy conservation and animal welfare concerns. From 1990 to 2011 the North Atlantic right whale (Eubalaena glacialis, NARW) population grew at a mean of 2.8% annually. However, population trends reversed since 2011; the species is in decline, with only ∼100 reproductively active females remaining. This failure is driven by vessel collisions and increasingly fatal and serious entanglement in fixed fishing gear, whose rope strength has increased substantially. Chronic entanglement, drag, and associated morbidity have been linked to poor fecundity. Genuine solutions involve designating areas to be avoided and speed restrictions for ships and removing fishing trap ropes from the water column. A trap fishing closure for NARW habitat in the Cape Cod Bay (U.S.) area has been in place seasonally since 2015. 2017 mortalities in Eastern Canada elicited substantive management changes whereby the 2018 presence of NARW in active trap fishing areas resulted in an effective closure. To avoid these costly closures, the traditional trap fishery model of rope end lines attached to surface marker buoys has to be modified so that traps are marked virtually, and retrieved with gear that does not remain in the water column except during trap retrieval. Consumer demand for genuinely whale-safe products will augment and encourage the necessary regulatory changes so that trap fisheries conserve target and nontarget species.
ICES assessments of cod (Gadus morhua) in the west of Scotland (ICES Division 6a) suggest the biomass has collapsed and that fishing mortality rate (F) has remained high. In contrast, other stocks in the same fishery, and adjacent cod stocks all show marked declines in fishing mortality and some recovery of the biomass. The perception of the status of 6a cod appears to be dependent on the assumption that the fishery exploitation pattern is flat topped. An assessment that allows the exploitation to take a domed shape produces results that suggest a marked decline in fishing mortality rate and that the spawning stock biomass has recovered to the minimum biomass reference point, Blim. The reduction in F is consistent with substantial reductions in fishing effort and shows a similar pattern to stocks taken within the same fishery. The management implications arising from the two assessments differ substantially. The analysis indicates that benchmark assessments need to test assessment model conditioning assumptions more widely and that management advice needs to consider a more comprehensive range of information about the stock and fishery.
Norway is the world’s largest producer of farmed Atlantic salmon and is home to ∼400 rivers containing wild salmon populations. Farmed escapees, a reoccurring challenge of all cage-based marine aquaculture, pose a threat to the genetic integrity, productivity, and evolutionary trajectories of wild populations. Escapees have been monitored in Norwegian rivers since 1989, and, a second-generation programme was established in 2014. The new programme includes data from summer angling, autumn angling, broodstock sampling, and snorkelling surveys in >200 rivers, and >25 000 scale samples are analysed annually. In 2014–2017, escapees were observed in two-thirds of rivers surveyed each year, and between 15 and 30 of the rivers had >10% recorded escapees annually. In the period 1989–2017, a reduction in the proportion of escapees in rivers was observed, despite a >6-fold increase in aquaculture production. This reflected improved escape prevention, and possibly changes in production methods that influence post-escape behaviour. On average, populations estimated to experience the greatest genetic introgression from farmed salmon up to 2014 also had the largest proportions of escapees in 2014–2017. Thus, populations already most affected are those at greatest risk of further impacts. These data feed into the annual risk-assessment of Norwegian aquaculture and form the basis for directing mitigation efforts.
The significance of the ocean and the resources that lie beneath it is well represented in the United Nations Sustainable Development Goals (SDGs). Specifically, Goal 14 of the SDGs highlights the need to conserve the ocean, seas and marine resources and, as such, is a significant contributor to the achievement of other SDGs. Goals 1 and 2 are aimed at bringing an end to poverty and hunger of which a plentiful supply of fish is an important means to their realisation. Fisheriesalso make a substantial contribution to the revenue of many developing countries, thereby assisting the attainment of Goal 8 which seeks to ensure sustainable economic growth. However, the pervasiveness of unsustainable practices that are harmful to the marine environment, such as pollution, overfishing and illegal, unreported and unregulated (IUU) fishing, threatens the ability of developing countries especially those in the Gulf of Guinea to maximise the use of their ocean resources. The paper focuses on the Gulf of Guinea due to the significance of fisheries resources to littoral communities and the severity of IUU fishing across the region. The paper also emphasises the threat to the fulfilment of some SDGs by 2030. It does so by arguing that unabated IUU fishing is due to respective government’s lack of awareness of their maritime domain, reflected in the dearth of human resource and inadequate financial investment to solve the problems of maritime security, and the lack of cooperation between countries in the region thus rendering existing surveillance operations ineffective.
We introduce an innovative value- and ecosystem-based management approach (VEBMA) that exposes resource policy tradeoffs, fosters good governance, and can help to resolve conflicts. We apply VEBMA to the Pacific herring Clupea pallasii fishery in British Columbia, Canada, which is mired in conflict between local and indigenous communities and the fishing industry over the management of herring, a forage fish with significant socioeconomic, ecological, and cultural value. VEBMA integrates an ecosystem-based approach (ecological modelling) with a value-based approach (practical ethics) to examine the ecological viability, economic feasibility, and societal desirability of alternative fishery management scenarios. In the ecosystem-based approach, we applied the Management Strategy Evaluation module within the Ecopath with Ecosim modelling framework to explore scenarios with harvest-control rules specified by various herring fishing mortalities and biomass cutoff thresholds. In the value-based approach, Haida Gwaii community and herring industry participants ranked a set of values and selected preferred scenarios and cutoff thresholds. The modelled ecological impacts and risks and stakeholder preferences of the scenarios are synthesized in a deliberation and decision-support tool, the VEBMA science-policy table. VEBMA aims to facilitate inclusive, transparent, and accountable decision-making among diverse stakeholders, such as local communities, industries, scientists, managers, and policy-makers. It promotes compromise, rather than consensus solutions to resolve ‘wicked’ problems at the science-policy interface.
The market demand for octopus grows each year, but landings are decreasing, and prices are rising. The present study investigated (1) diversity of Octopodidae in the Western Indian Ocean (WIO) and (2) connectivity and genetic structure of Octopus cyanea and O. vulgaris populations in order to obtain baseline data for management plans. A fragment of the cytochrome C oxidase subunit 1 (COI) gene was sequenced in 275 octopus individuals from Madagascar, Kenya and Tanzania. In addition, 41 sequences of O. vulgaris from South Africa, Brazil, Amsterdam Island, Tristan da Cunha, Senegal and Galicia were retrieved from databases and included in this study. Five different species were identified using DNA barcoding, with first records for O. oliveri and Callistoctopus luteus in the WIO. For O. cyanea (n = 229, 563 bp), 22 haplotypes were found, forming one haplogroup. AMOVA revealed shallow but significant genetic population structure among all sites (ϕST = 0.025, p = 0.02), with significant differentiation among: (1) Kanamai, (2) southern Kenya, Tanzania, North and West Madagascar, (3) Southwest Madagascar and (4) East Madagascar (ϕCT = 0.035, p = 0.017). For O. vulgaris (n = 71, 482 bp), 15 haplotypes were identified, forming three haplogroups. A significant genetic population structure was found among all sites (ϕST = 0.82, p ≤ 0.01). Based on pairwise ϕST-values and hierarchical AMOVAs, populations of O. vulgaris could be grouped as follows: (1) Brazil, (2) Madagascar and (3) all other sites. A significant increase in genetic distance with increasing geographic distance was found (Z = 232443, 81 r = 0.36, p = 0.039). These results indicate that for O. cyanea four regions should be considered as separate management units in the WIO. The very divergent haplogroups in O. vulgaris from Brazil and Madagascar might be evolving towards speciation and therefore should be considered as separate species in FAO statistics.
Populations of small pelagic fish (SPF) such as sardine, anchovy, herring, capelin and mackerel provide ~25% of the global annual yield of capture fisheries, and the well-being of many human coastal communities around the world, particularly in developing countries, critically depends on these SPF resources. These fishes display large ‘boom and bust’ cycles with great ecological as well socioeconomic consequences. Despite many internationally coordinated research efforts, sufficient knowledge about the drivers of SPF population dynamics and, particularly, the interactive effects of environmental and anthropogenic factors is lacking. The ecology and management of SPF were discussed in a symposium in Victoria, BC (Canada), attracting participants from 31 countries. This Theme Section consists of 22 research contributions providing fundamental insights into (1) the biology of SPF, (2) the drivers of SPF dynamics and (3) the socioeconomic impacts of SPF fisheries. Such insights are urgently needed for effective, ecosystem-based management of these highly variable fish populations. The symposium was an important catalyst for future, internationally coordinated research efforts to further advance our knowledge on the drivers of SPF population dynamics and the effective management of SPF fisheries.
Settlement funds from catastrophes can generate lasting conservation benefits, if directed appropriately. Such is the case with the Nestucca oil spill which occurred in Washington State in 1988. The spill killed thousands of marine birds and the subsequent litigation settlement awarded 3.3 million dollars for recovery and monitoring of Canadian seabirds, in addition to clean-up costs. Settlement damage funds were directed to eradicate introduced rats from Langara Island, to restore what was formerly the world's largest colony of Ancient Murrelets (Synthliboramphus antiquus). In addition, settlement funds were devoted to establishing an ecosystem-level baseline of seabirds and their marine prey populations on Triangle Island, the largest and most diverse seabird colony in Western Canada. One of the projects tracked breeding Cassin's Auklet (Ptychoramphus aleuticus) and determined that they foraged far away from the colony in search of deep-sea copepods. The results stimulated conservation planners to enlarge a marine protected area which had been proposed to protect marine birds in the region, but policy guidance was lacking. By 2018 policies had evolved, and Canada announced the formation of their first marine National Wildlife Area following a multi-year engagement process with many interested parties. At the same time, Shell Canada relinquished all of their exploratory drilling rights within the area. The settlement funds from a catastrophic oil spill facilitated the recovery of seabirds on Langara Island, the formation of the first marine protected area for wildlife in Canada, and a reduction of future threats from exploratory drilling in an internationally important ecosystem.
The productivity of marine ecosystems and the services they provide to humans are largely dependent on complex interactions between prey and predators. These are embedded in a diverse network of trophic interactions, resulting in a cascade of events following perturbations such as species extinction. The sheer scale of oceans, however, precludes the characterization of marine feeding networks through de novo sampling. This effort ought instead to rely on a combination of extensive data and inference. Here we investigate how the distribution of trophic interactions at the global scale shapes the marine fish food web structure. We hypothesize that the heterogeneous distribution of species ranges in biogeographic regions should concentrate interactions in the warmest areas and within species groups. We find that the inferred global metaweb of marine fish—that is, all possible potential feeding links between co-occurring species—is highly connected geographically with a low degree of spatial modularity. Metrics of network structure correlate with sea surface temperature and tend to peak towards the tropics. In contrast to open-water communities, coastal food webs have greater interaction redundancy, which may confer robustness to species extinction. Our results suggest that marine ecosystems are connected yet display some resistance to perturbations because of high robustness at most locations.
Global concern about floating marine debris and its fundamental role in shaping coastal biodiversity is growing, yet there is very little knowledge about debris-associated rafting communities in many areas of the world's oceans. In the present study, we examined the encrusting assemblage on different types of stranded debris (wood, plastic, glass, and metal cans) along the Iranian coast of the Persian Gulf. In total, 21 taxa were identified on 132 items. The average frequency of occurrence (±SE) across all sites and stranded debris showed that the barnacle Amphibalanus amphitrite(68.9 ± 1.1%), the oyster Saccostrea cucullata (40.9 ± 0.7%), the polychaete Spirobranchus kraussii (27.3 ± 0.5%), green algae (22 ± 0.5%) and the coral Paracyathus stokesii(14.4 ± 0.7%) occurred most frequently. Relative substratum coverage was highest for A. amphitrite(44.3 ± 2.7%), followed by green algae (14.4 ± 1.5%), Spirobranchus kraussii (9.3 ± 1.3%), Saccostrea cucullata(7.6 ± 1.3%) and the barnacle Microeuraphia permitini(5.8 ± 0.9%). Despite the significant difference in coverage of rafting species on plastic items among different sites, there was no clear and consistent trend of species richness and coverage from the eastern (Strait of Hormuz) to the western part of the Persian Gulf. Some rafting species (bryozoans and likely barnacles) were found to be non-indigenous species in the area. As floating marine debris can transport non-indigenous species and increase the risk of bio-invasions to this already naturally- and anthropogenically-stressed water body, comprehensive monitoring efforts should be made to elucidate the vectors and arrival of new invasive species to the region.
Shark and ray megafauna have crucial roles as top predators in many marine ecosystems, but are currently among the most threatened vertebrates and, based on historical extinctions, may be highly susceptible to future environmental perturbations. However, our understanding of their energetics lags behind that of other taxa. Such knowledge is required to answer important ecological questions and predict their responses to ocean warming, which may be limited by expanding ocean deoxygenation and declining prey availability. To develop bioenergetics models for shark and ray megafauna, incremental improvements in respirometry systems are useful but unlikely to accommodate the largest species. Advances in biologging tools and modelling could help answer the most pressing ecological questions about these iconic species.
Sustainable landscape planning and management of coastal habitats has become an integral part of the global agenda due to anthroprogenic pressures and climate change-induced events. As an example of human-engineered infrastructure that enhances the sustainability and resilience of coastal social-ecological systems (SES), we have presented the dumbeong system, a farmer-engineered and managed irrigation system based on Korean traditional ecological knowledge. We analyzed the spatial relationship of dumbeongs with coastal landscape attributes and droughts in Goseong County in South Korea. We used generalized linear models (GLMs) to examine the effects of land cover and recent (2001–2010) standardized precipitation index (SPI) on the abundance of dumbeongs. Then, we projected near future (2020–2050) changes in the SPI-based drought risk for the dumbeong system using representative concentration pathway (RCP) climate scenarios. We found that forest and marine water areas have positive relations with dumbeong abundance, whereas SPI has a negative relation, indicating that the dumbeongs are more abundant in areas close to sea water and forests, and with higher incidences of drought. Derived climate change scenarios show that the study region will experience higher incidence of drought. Our findings provide empirical evidence for the dumbeongsystem as an effective community designed and driven adaptive response to local hydrological processes and climatic conditions, and as climate-resilient infrastructure that strengthens sustainability and resilience of coastal SES. Based on our findings, we provide recommendations for sustainable landscape management and optimal use of the dumbeong system in coastal regions.
Marine debris is defined as any persistent solid material disposed into the marine and/or coastal environment. The impact of these pieces of debris, especially plastic, have been reported around the world as causing environmental degradation, disease dissemination, transport of chemical toxins and public health issues. The extent of the effects of marine debris and beach cleanliness can be assessed using indexes such as General Index (GI), Clean-Coast Index (CCI) and Pellet Pollution Index (PPI). Thus, this study analyzed all debris collected from 25 beaches located in 11 counties in the State of Santa Catarina, Brazil. The quali-quantitative analysis was used for individual beaches according to the above indexes. Although plastic was the overall most common debris category, granulated polystyrene was the most common debris in nine of the beaches in this study. From the three indexes employed in this study, GI appears to be the most appropriate as it considers all debris sizes, while CCI underestimates the pollution level of the beaches as it only takes into consideration plastic debris over 2 cm. Similarly, PPI ranked all sites as having low pollution levels, despite the high threats that pellets may pose to marine biota.
Items of marine plastic litter are conventionally classified as primary or secondary, depending on whether they are distinct objects or angular fragments, respectively. “Pyroplastic” is an additional type of plastic litter that is described here, based on observations made on beached samples from south west England. Pyroplastics are derived from the informal or more organised burning of manufactured plastics and may be angular “plastiglomerates”, comprising pieces of plastic debris within a matrix, or rounded plastic “pebbles”, where agglomerated material has been weathered and smoothed into more brittle and neutrally-coloured geogenic-looking clasts. Beached pyroplastics are usually positively buoyant because of a polyethylene or polypropylene matrix, and exhibit a bimodal mass distribution attributed to the breakage of larger clasts (>20 mm) into smaller fragments (<5 mm). XRF analysis reveals variable quantities of Pb in the matrix (up to 7500 μg g−1), often in the presence of Cr, implying that material in many samples pre-dates restrictions on the use of lead chromate. Low concentrations of Br and Sb relative to pieces of manufactured plastics in the marine environment suggest that pyroplastics are not directly or indirectly derived from electronic plastic. Calcareous worm tubes on the surfaces of pyroplastics dense enough to be temporarily submerged in the circalittoral zone are enriched in Pb, suggesting that constituents within the matrix are partly bioavailable. Evading ready detection due to their striking visual similarity to geogenic material, pyroplastics may contribute to an underestimation of the stock of beached plastics in many cases.
Plastic debris becomes currently a ubiquitous environmental pollutant and is susceptible to contamination by many other pollutants, including aqueous metals and organic matter. This review summarizes the effects of environmental factors on the properties and sorption behavior of microplastics, presents a further discussion on the fate of microplastics adsorption on contaminants, and critically discusses the mechanism of sorption behaviors between micro/nanoplastics and normal contaminants. Previous references indicated that the hydrophobicity and particle sizes of microplastics were the dominant influence factors for virgin plastic debris adsorption, whereas for aged microplastics, hydrogen bonding, hydrophilicity and increasing specific surface ratio affected the adsorption behavior. The effects of pH and salinity always influence the sorption conditions by changing the charge state of microplastics and contaminants and causing competing adsorption. In addition, the existence of microplastics affects biotoxicity, increases the dissolved organic matter in the environment, and influences carbon cycling. The knowledge is fundamental to the assessment of potential risks posed by microplastics to organisms from human beings to the entire environment.
Tidal habitats sustain fragile ecosystems, undergoing pressures from coastal artificialization and rising sea levels. Saltpans are a substitution habitat for birds that breed, winter or stop-over along coastlands where most pristine tidal habitats have been removed. Balancing the economical, patrimonial and biodiversity values of former saltpans is thus needed to mitigate the threats posed by global changes on waterbirds. In this study, we scrutinized the influence of management practices on waterbirds on two isolated saltpans located on the French Mediterranean shore, several tens of kilometres apart from other suitable habitats. We analysed three years of bird counts for nine protected species that breed, forage and roost on these saltpans. We used a multispecies hierarchical model to relate variations in bird counts to water levels, oxygenation and salinity, the three parameters targeted by the saltpans management plan to promote bird settlement. We showed that the hypersaline conditions that dominate in these saltpans are suboptimum to most species, suggesting that waterbird concentrations are dictated by the lack of alternatives in the surrounding landscape rather than by habitat suitability. Intraspecific variations in species' responses to these variables should orient towards the creation of a habitat mosaic within the saltpans. Eventually, between-site differences in bird responses to water conditions pointed the effects of disturbance, predation and other landscape-level features. Our results reveal that high waterbird numbers on isolated saltpans may be a misleading measure of their ecological suitability, and that management on these sites needs to incorporate conflicts and complementarity in species' habitat use.
Ecological resilience, broadly defined as the magnitude of the disturbance a system needs to shift to an alternative stable state, is becoming a critical trait in the Anthropocene era. However, we are far from having baseline resilience data to guide decision makers toward more resilient ecological systems. In the last decade, the resilience assessment framework has taken a sum of products approach to obtain a resilience indicator based on the relevance and the intensity of multiple factors. While factor intensity relies on quantitative data, estimates of factor relevance rely on ordinal data with a lesser understanding of their relative importance to resilience, which may have consequences in the value of the resilience indicator. Here, we computed three resilience indicators to test for the quantitative impact that changes in factor relevance might cause to the resilience indicator. We defined the Inclusive Resilience Indicator of a Site (IRIS) as a relevance-free indicator based exclusively on factor intensity. We also computed the Relative Resilience Potential (RRP) and an RRP with random relevance values (RRPrrv) as indicators based on both intensity and relevance. To calculate these three indicators in rocky reefs of the Alboran Sea, we quantified 17 biological, environmental, and human-related factors known to influence resilience. We used correlation analyses, Linear Mixed Models, and Generalized Additive Models to compare the three resilience indicators and to examine their spatial patterns. We found highly significant positive correlations between the RRP, RRPrrv, and IRISindicators (r > 0.9, p < 0.001 for all comparisons). All three indicators had equivalent resilience values (p = 0.440), provided non-significant differences in their predictions (p = 0.097), and exposed the same resilience gradients in the Alboran Sea (p < 0.001 for all indicators). IRISaccounted for 94% and 99% of the variance associated with RRP and RRPrrv, respectively, suggesting that the intensity-based IRIS can estimate resilience without the uncertainties associated with factor relevance. The new IRIS indicator proposed in our study may facilitate the acquisition of baseline data needed to further advance in the ecological and management implications of marine resilience.
The spatial structure and dynamics of populations, their environment, interacting species, and anthropogenic stressors influences community stability and ecological resilience. Despite the importance of spatial processes in ecological outcomes and increasing desire to implement ecosystem-based management, fine-scale spatial dynamics have been rarely incorporated in marine fisheries management. However, advances in population modeling and data availability provide the necessary ingredients to address this disconnect between the fields of ecology and fisheries. We used random forests and spatial indices to quantify spatial heterogeneity and dynamics of US west coast demersal marine faunal density (biomass of a community or assemblage per unit area) and the total removals (catches plus discards) from the system by the groundfish bottom trawl fishery from 2002 to 2017. We expected spatial heterogeneity of removals and density to increase following implementation of depth and habitat closures – due to proximally increasing density gradients and fishing-the-line – and following catch shares because of fleet consolidation and behavioral consequences of eliminating the race to fish. However, we found mixed responses, where at the broadest community levels spatial variation in removals and density declined with habitat closures, while spatial autocorrelation of removals increased with habitat closures and declined with catch shares. Our results reveal a complex interdependence between spatial distributions of faunal density and fishery removals that has been absent in previous studies focusing on catch only, and shows how these patterns are shaped by marine policy. Values of spatial variation of density and removals were positively correlated within year (i.e., each responded with the same sign and timescale), while there was also evidence that interannual changes in the spatial variation of removals among years led those of density by one year (i.e., increases in patchiness of removals were followed by increased patchiness of density). These results hint at the presence of a stronger than expected top-down effect of fishing, given that this system is considered to be dominated by strong bottom-up effects of environmental variation on primary and secondary productivity.
This paper examines governance effectiveness of the Wildlife Refuge of Punta de Manabique (RVSPM), the first recognized marine protected area in Guatemala. The analysis follows the Marine Protected Area Governance (MPAG) empirical framework through the use of incentives (economic, interpretative, knowledge, legal and participative) that evaluate the effectiveness of governance. Our results highlight that strategic alliances between some local communities and NGOs have successfully provided economic and participatory incentives for better management. However, efforts to develop an integrated or collaborative management system that promotes sustainable resource use across all stakeholder groups have failed. As a result, environmental degradation is increasing at an alarming rate, set against a backdrop of declining management effectiveness. Under this scenario, future prospects for governance should revise participatory incentives and strengthen legal incentives, which should be backed by strong political will. In addition, efforts should continue to foster opportunities for regional collaborations as an essential element for improved governance of the RVSPM and as a foundation to effectively manage natural and cultural resources in the wider Mesoamerican Reef region.