Large Marine Ecosystems located around the margins of the continents provide a countless number of goods and services that sustain and fulfill human life and activities: seafood; habitats; energy sources; nutrient cycling and primary production; weather and climate regulation; coastal protection; water detoxification; sediments trapping; and cultural and economic services, among others. Of 66 Large Marine Ecosystems, ten LMEs are located along the coasts of Latin America – California Current, Gulf of California, Gulf of Mexico, Pacific Central American Coastal, Caribbean Sea, Humboldt Current, Patagonian Shelf, South Brazil Shelf, East Brazil Shelf and North Brazil Shelf. Each one possesses different characteristics that make it unique and essential for local populations. Unfortunately, these Large Marine Ecosystems are threatened by several factors such as coastal population growth, pollution, overexploitation and climate change, but most of all poor governance practice. The concept of Ecosystem Based Management aims to consider ecosystems health and importance in all aspects of the recovery and sustainability of LME goods and services. This chapter introduces a general description of the Large Marine Ecosystem approach to sustainable development of coastal ocean resources, presents the concept of Ecosystem Based Management, describes some goods and services provided by Large Marine Ecosystems and draws a picture of each Latin American Large Marine Ecosystem.
The Peru-Chile GEF-UNDP-Humboldt Current Large Marine Ecosystem Project successfully completed its first five-year phase. It included the delivery of ten thematic reports (TR), a Causal Chain Analysis (CCA), Ecosystem Diagnostic Analyses (EDA)(one each for Chile and Peru), a Transboundary Diagnostic Analysis (TDA) and a Strategic Action Program (SAP). The transboundary problems affecting the state of goods and services provided by the Humboldt Current Large Marine Ecosystem (HCLME) are: (1) non optimal use of fishing resources with socio-economic consequences; (2) anthropogenic disturbance of marine habitats after an increase in pollution levels within the HCLME; and (3) high incidental by-catch and associated fauna destruction and discards as a common problem for the two countries. Governance aspects developed during the past five years (2011-16) included, a “bottom-up” process in Peru and Chile linked to the establishment of new fishing and aquaculture acts, Marine Protected Areas and territorial use rights for artisanal fisheries, new methods for fish stock assessment, and ecolabelling of fisheries, among others. Management plans have been designed for pilot sites: the Juan Fernandez Archipelago in Chile; and Lobos de Tierra Island, Ballestas Islands and San Juan cape in Peru.
A first Total Economic Value calculation of the goods and services provided by the HCLME in 2015 indicates a delivery of US$19.45 billion per annum. This value comprises 58% from Chile (US$ 11.28 billion) and 42% from Peru (US$ 8.17 billion). Additionally, the area of direct influence of the Humboldt Current System generates 77% (US$ 14.97 billion) of the value produced by the HCLME, where the tropical area of Peru and the southern area of Chile added 2% (US$ 0.45 billion) and 21% (US$ 4.03 billion), respectively.
Possible scenarios of climate change in the HCLME were focused on the changes of biogeochemical alterations and forcing on the productivity and abundance-distribution of key species. Currently, high ocean productivity is an expression of the relatively high biomass of pelagic fish like anchovy, pacific jack mackerel and sardine, also other fishing resources like demersal fish (hake), cephalopod molluscs (squid), crustaceans (shrimp) have important contributions. Nevertheless, a deeper analysis of the impacts of climate on the fisheries and coastal areas of the HCLME is needed.
Marine mammals attract human interest – sometimes this interest is benign or positive – whale watching, conservation programmes for whales, seals, otters, and efforts to clear beaches of marine debris are seen as proactive steps to support these animals. However, there are many forces operating to affect adversely the lives of whales, seals, manatees, otters and polar bears – and this book explores how the welfare of marine mammals has been affected and how they have adapted, moved, responded and sometimes suffered as a result of the changing marine and human world around them. Marine mammal welfare addresses the welfare effects of marine debris, of human traffic in the oceans, of noise, of hunting, of whale watching and tourism, and of some of the less obvious impacts on marine mammals – on their social structures, on their behaviours and migration, and also of the effects on captivity for animals kept in zoos and aquaria. There is much to think and talk about – how marine mammals respond in a world dramatically influenced by man, how are their social structures affected and how is their welfare impacted?
Sharks, rays, and chimaeras (Class Chondrichthyes; herein 'sharks') are the earliest extant jawed vertebrates and exhibit some of the greatest functional diversity of all vertebrates. Ecologically, they influence energy transfer vertically through trophic levels and sometimes trophic cascades via direct consumption and predation risk. Through movements and migrations, they connect horizontally and temporally across habitats and ecosystems, integrating energy flows at large spatial scales and across time. This connectivity flows from ontogenetic growth in size and spatial movements, which in turn underpins their relatively low reproductive rates compared with other exploited ocean fishes. Sharks are also ecologically and demographically diverse and are taken in a wide variety of fisheries for multiple products (e.g. meat, fins, teeth, and gills). Consequently, a range of fisheries management measures are generally preferable to 'silver bullet' and 'one size fits all' conservation actions. Some species with extremely low annual reproductive output can easily become endangered and hence require strict protections to minimize mortality. Other, more prolific species can withstand fishing over the long term if catches are subject to effective catch limits throughout the species' range. We identify, based on the IUCN Red List status, 64 endangered species in particular need of new or stricter protections and 514 species in need of improvements to fisheries management. We designate priority countries for such actions, recognizing the widely differing fishing pressures and conservation capacity. We hope that this analysis assists efforts to ensure this group of ecologically important and evolutionarily distinct animals can support both ocean ecosystems and human activities in the future.
Knowledge of the extent and intensity of fishing activities is critical to inform management in relation to fishing impacts on marine conservation features. Such information can also provide insight into the potential socio-economic impacts of closures (or other restrictions) of fishing grounds that could occur through the future designation of Marine Conservation Zones (MCZs). We assessed the accuracy and validity of fishing effort data (spatial extent and relative effort) obtained from Fishers’ Local Knowledge (LK) data compared to that derived from Vessel Monitoring System (VMS) data for a high-value shellfish fishery, the king scallop (Pecten maximus L.) dredge fishery in the English Channel. The spatial distribution of fishing effort from LK significantly correlated with VMS data and the correlation increased with increasing grid cell resolution. Using a larger grid cell size for data aggregation increases the estimation of the total area of seabed impacted by the fishery. In the absence of historical VMS data for vessels ≤15 m LOA (Length Overall), LK data for the inshore fleet provided important insights into the relative effort of the inshore (<6 NM from land) king scallop fishing fleet in the English Channel. The LK data provided a good representation of the spatial extent of inshore fishing activity, whereas representation of the offshore fishery was more precautionary in terms of defining total impact. Significantly, the data highlighted frequently fished areas of particular importance to the inshore fleet. In the absence of independent sources of geospatial information, the use of LK can inform the development of marine planning in relation to both sustainable fishing and conservation objectives, and has application in both developed and developing countries where VMS technology is not utilised in fisheries management.
The Convention on Biological Diversity mandates the establishment of Marine Protected Area (MPA) networks worldwide, with recommendations stating the importance of ‘ecological coherence,’ a responsibility to support and perpetuate the existing ecosystem, implying the need to sustain population connectivity. While recommendations exist for integrating connectivity data into MPA planning, little advice exists on how to assess the connectivity of existing networks. This study makes use of recently observed larval characteristics and freely available models to demonstrate how such an assessment could be undertaken. The cold water coral (CWC) Lophelia pertusa (Linnaeus, 1758) is used as a model species, as much of the NE Atlantic MPA network has been designated for CWC reef protection, but the ecological coherence of the network has yet to be assessed. Simulations are run for different behavioural null models allowing a comparison of ‘passive’ (current driven) and ‘active’ (currents + vertical migration) dispersal, while an average prediction is used for MPA assessment. This model suggests that the network may support widespread larval exchange and has good local retention rates but still has room for improvement. The best performing MPAs were large and central to the network facilitating transport across local dispersal barriers. On average, passive and active dispersal simulations gave statistically similar results, providing encouragement to future local dispersal assessments where active characteristics are unknown.
In July 2015, Scotland became one of the first countries to sign up to the UN Sustainable Development Goals (SDGs) which, unlike their forerunner the Millennium Development Goals, are not restricted to developing nations. Their respective targets should drive policy decisions for Scottish fisheries, in keeping with the universal intent of the new goals. This paper explores the relevance of SDG 14 to the Scottish fishing industry, noting that there are a number of linkages with other goals and targets that should be considered within management frameworks. Scottish fishing has a long history, but the size of the inshore fleet has seen decline in recent decades, particularly of small-scale fishers in rural communities. Available literature was reviewed and a survey of active Scottish fishers conducted to explore the current availability and equality of distribution of benefits from ecosystem services to Scottish fisheries, and the factors that affect them. The findings suggest that benefits may not currently be equally distributed across Scottish fisheries; this is largely sector dependent and driven by market forces, but also relates to gaps in current management and monitoring systems. Furthermore, the potential benefits to fisheries of marine protected areas (MPAs) established for conservation purposes are not adequately assessed as part of their design, which may result in less support from fisheries stakeholders and reduce the benefit to ecosystem services. It concludes with some recommendations for consideration by decision-makers to improve how fishing businesses and communities could benefit more from ecosystem services whilst operating within environmental limits.
Marine Protected Areas (MPA) can be powerful coastal management tools with several specific goals, although there is debate concerning their effectiveness. There is no consensus regarding the ideal size of MPAs, and actually there is some evidence that perhaps size is not as critical as other specific factors in determining their success in terms of populations’ protection and ecological functions conservation. On the other hand, depending on the objectives, zones with different classification regimes in terms of rules and uses might enable the maintenance of the intended uses.
At this light, we examined the case of the small (605 002 m2) rocky shore area of Avencas, near Lisbon, on the Atlantic western Coast of Portugal, which was classified as Biophysical Interest Zone (ZIBA) in 1998, due to its exceptional intertidal biodiversity, after what its protection status became controversial, leading to conflicts with the local population and incompliance with extant regulations. From 2010 efforts were carried out by local authorities to reclassify Avencas as Marine Protected Area, which was achieved in 2016.
Monitoring intertidal communities in a MPA and adjacent areas is an effective and low-cost procedure to evaluate the evolution of the biodiversity of rocky shores. Therefore, antedating the creation of the new MPA, assessments of the ZIBA biodiversity were conducted from January 2013 to December 2015 on a monthly basis. This timeline was selected as a function of a change in visitors’ behavior induced from 2013 by several management and outreach initiatives, which increased in a certain extent the user’s compliance with regulations.
A positive evolution was expected for density and/or species diversity of the different groups analysed (flora, sessile fauna and mobile fauna) in this three years period. However, a very strong storm occurred in 2014 produced a significant impact and changed large areas of the Avencas rocky shore. As a consequence, results did not display a recognizable recovery pattern of the intertidal communities, and following that extreme event are not even consistent with a hypothesized enhanced recovery capability of the ecosystem in a protected area. This suggests that longer data series are necessary to obtain more robust data regarding natural variability, since alterations caused by extreme events are always likely to occur. Additionally, results illustrate that indeed size matters because it influences the MPA openness, expressed as the ratio of periphery to area, and therefore its susceptibility to external driving forces. Such considerations must be taken into account in any management plan, which in this case should encompass an increase in the intertidal protected area, a new conditioned small-scale fishing regime, and an adequate monitoring programme to evaluate the effectiveness of the new management scheme.
This paper assesses challenges for social impact assessment (SIA) for coastal and offshore infrastructure projects, using the case study of the Tomakomai Carbon Capture and Storage (CCS) Demonstration Project in Hokkaido, Japan. Interest in SIA and linked concepts such as social licence to operate is growing, yet marine environments also have potential to raise additional complexity in project governance. Drawing on qualitative research conducted in Tomakomai and Japan more widely across the project development and implementation phase, the paper argues that building an understanding of the social, cultural and historical relationship between the community, industry and the sea is crucial to understanding the neutral or cautiously supportive response of the citizens and stakeholders in Tomakomai to the project. Moreover, effective SIA in coastal regions needs to find a way to account for – or at least make visible – these complex relations between society and the sea. Based on the findings, it is suggested that developers or policymakers overseeing SIA in coastal regions ought to pay extra attention to the extent to which developments like CCS are viewed by communities as 'new' as opposed to a continuation of existing activities in the sea; to the importance of engagement on monitoring during the project operations phase; and to the non-economic values such as pride and identity which communities and stakeholders may derive from the sea.
Understanding the impacts of recreational fishing on habitats and species, as well as the social and ecological importance of place to anglers, requires information on the spatial distribution of fishing activities. This study documented long-term changes in core fishing areas of a major recreational fishery in Alaska and identified biological, regulatory, social, and economic drivers of spatial fishing patterns by charter operators. Using participatory mapping and in-person interviews, we characterized the spatial footprint of 46 charter operators in the communities of Sitka and Homer since the 1990s. The spatial footprint differed between Homer and Sitka respondents, with Homer operators consistently using larger areas for Pacific halibut than Sitka operators. Homer and Sitka showed opposite trends in core fishing location area over time, with an overall decrease in Homer and an overall increase in Sitka. For both Sitka and Homer respondents, the range of areas fished was greater for Pacific halibut than for rockfish/lingcod or Pacific salmon. Spatial patterns were qualitatively different between businesses specializing in single species trips and those that operated multispecies trips and between businesses with one vessel and those with multiple vessels. In Homer, the most frequently cited reasons for changes in the location and/or extent of fishing were changes in trip type and the price of fuel, while in Sitka, the most frequently cited reasons for spatial shifts were changes to Pacific halibut regulations and gaining experience or exploring new locations. The diversity of charter fishing strategies in Alaska may allow individual charter operators to respond differently to perturbations and thus maintain resilience of the industry as a whole to social, environmental, and regulatory change. This research also highlights the importance of understanding fishers’ diverse portfolio of activities to effective ecosystem-based management.
With projected changes in the marine environment under global climate change, the effects of single stressors on corals have been relatively well studied. However, more focus should be placed on the interactive effects of multiple stressors if their impacts upon corals are to be assessed more realistically. Elevation of sea surface temperature is projected under global climate change, and future increases in precipitation extremes related to the monsoon are also expected. Thus, the lowering of salinity could become a more common phenomenon and its impact on corals could be significant as extreme precipitation usually occurs during the coral spawning season. Here, we investigated the interactive effects of temperature [24, 27 (ambient), 30, 32°C] and salinity [33 psu (ambient), 30, 26, 22, 18, 14 psu] on larval settlement, post-settlement survival and early growth of the dominant coral Platygyra acuta from Hong Kong, a marginal environment for coral growth. The results indicate that elevated temperatures (+3°C and +5°C above ambient) did not have any significant effects on larval settlement success and post-settlement survival for up to 56 days of prolonged exposure. Such thermal tolerance was markedly higher than that reported in the literature for other coral species. Moreover, there was a positive effect of these elevated temperatures in reducing the negative effects of lowered salinity (26 psu) on settlement success. The enhanced settlement success brought about by elevated temperatures, together with the high post-settlement survival recorded up to 44 and 8 days of exposure under +3°C and +5°C ambient respectively, resulted in the overall positive effects of elevated temperatures on recruitment success. These results suggest that projected elevation in temperature over the next century should not pose any major problem for the recruitment success of P. acuta. The combined effects of higher temperatures and lowered salinity (26 psu) could even be beneficial. Therefore, corals that are currently present in marginal environments like Hong Kong, as exemplified by the dominant P. acuta, are likely to persist in a warmer and intermittently less saline, future ocean.
Future impacts of climate change on marine fisheries have the potential to negatively influence a wide range of socio-economic factors, including food security, livelihoods and public health, and even to reshape development trajectories and spark transboundary conflict. Yet there is considerable variability in the vulnerability of countries around the world to these effects. We calculate a vulnerability index of 147 countries by drawing on the most recent data related to the impacts of climate change on marine fisheries. Building on the Intergovernmental Panel on Climate Change framework for vulnerability, we first construct aggregate indices for exposure, sensitivity and adaptive capacity using 12 primary variables. Seven out of the ten most vulnerable countries on the resulting index are Small Island Developing States, and the top quartile of the index includes countries located in Africa (17), Asia (7), North America and the Caribbean (4) and Oceania (8). More than 87% of least developed countries are found within the top half of the vulnerability index, while the bottom half includes all but one of the Organization for Economic Co-operation and Development member states. This is primarily due to the tremendous variation in countries’ adaptive capacity, as no such trends are evident from the exposure or sensitivity indices. A negative correlation exists between vulnerability and per capita carbon emissions, and the clustering of states at different levels of development across the vulnerability index suggests growing barriers to meeting global commitments to reducing inequality, promoting human well-being and ensuring sustainable cities and communities. The index provides a useful tool for prioritizing the allocation of climate finance, as well as activities aimed at capacity building and the transfer of marine technology.
The UK network of Marine Protected Areas and the application of management measures to protect conservation features has grown over the past decade. Bodies that regulate activities within MPAs require advice from ‘statutory’ conservation bodies. Therefore to assess the developing MPA networks resilience it is important to assess the ability of bodies to provide effective conservation advice. Thus ‘Natural England’ officers were interviewed to assess their ability to provide scientific advice on the impacts of operations in English MPAs. Results highlight the opinions of UK statutory conservation advisors to be able to provide concrete evidence on the impact of MPA designations and management measures. Response scores were ranked from 1 to 5, with 1 representing a low score, and 5, high. For governance, there was a very positive response to the structures in place to provide conservation advice (4.5). However, in terms of the finance available to provide adequate scientific advice, responses scored lower at 3.1. The majority of NE respondents believe the budget available for ‘feature condition assessment’ to be insufficient for the current MPA network, with most advice derived from ‘expert judgement’ based on the precautionary principle rather than site-based observation of ‘cause-and-effect’ from different human activities. Yet although budgets are a problem, the relationship between Natural England and local fisheries regulators is very healthy, resulting in better joined-up communication over management measures applied to stakeholders. Hence this research recommends the development of private-public partnerships (co-management initiatives) to reduce costs, bring in affected stakeholders and their assets, and improve trust.
Although highly recognized as needed, studies linking gender and coastal/marine management are scarce. This research illustrates the importance of gender analysis in natural resource management by linking gender and coastal management i.e. Marine Spatial Planning. The research was conducted in various Zanzibar seascapes (Unguja Island, Tanzania). Using a typology comprising gender structure, symbolism and identity; the results show a clear gendered division of labor, highly associated with a gender symbolism in which traditional roles of women as responsible for reproduction activities played a major role. Men used the whole seascape for their activities, while women remained in coastal forests and shallow areas collecting wood, invertebrates and farming seaweed. These activities allowed women to combine productive and reproductive work. Ecosystem importance for subsistence decreased with distance from land for both genders, while the importance for income increased with distance for men. Both genders acknowledged seagrasses as very important for income. Income closely followed the universal pattern of men earning more. Identities were defined by traditional ideas like “women are housewives”, while men identities were strongly associated with fisheries with reinforced masculinity. Livelihood diversity was higher for women also showing a tendency of slow change into other roles. Management was found to be strongly androcentric, revealing a deep gender inequality. The research exemplifies how a gender analysis can be conducted for management enhancement. It also invites replication around the world. If management is found to be androcentric in coastal locations elsewhere, a serious gender inequality can be at hand at global level.
Climate change is driving a pervasive global redistribution of the planet's species. Species redistribution poses new questions for the study of ecosystems, conservation science and human societies that require a coordinated and integrated approach. Here we review recent progress, key gaps and strategic directions in this nascent research area, emphasising emerging themes in species redistribution biology, the importance of understanding underlying drivers and the need to anticipate novel outcomes of changes in species ranges. We highlight that species redistribution has manifest implications across multiple temporal and spatial scales and from genes to ecosystems. Understanding range shifts from ecological, physiological, genetic and biogeographical perspectives is essential for informing changing paradigms in conservation science and for designing conservation strategies that incorporate changing population connectivity and advance adaptation to climate change. Species redistributions present challenges for human well-being, environmental management and sustainable development. By synthesising recent approaches, theories and tools, our review establishes an interdisciplinary foundation for the development of future research on species redistribution. Specifically, we demonstrate how ecological, conservation and social research on species redistribution can best be achieved by working across disciplinary boundaries to develop and implement solutions to climate change challenges. Future studies should therefore integrate existing and complementary scientific frameworks while incorporating social science and human-centred approaches. Finally, we emphasise that the best science will not be useful unless more scientists engage with managers, policy makers and the public to develop responsible and socially acceptable options for the global challenges arising from species redistributions.
Entanglement in and ingestion of marine debris by marine life has become a recognized threat worldwide, and the endangered Florida manatee is no exception. Manatees are known to become entangled in various types of fishing gear and other marine debris, and foreign objects are often found in the gastrointestinal tract of dead manatees. We examined a 20 yr dataset (1993 to 2012) of manatee rescue and necropsy records for evidence of entanglement in or ingestion of marine debris. In over 6500 manatee necropsy reports, over 11% either had ingested or showed evidence of entanglement in marine debris (or both). Fifty manatees died as a direct result of either entanglement in or, most commonly, ingestion of marine debris; fishery-related gear was involved in over 70% of these cases. With respect to live manatee rescues (n = 1244), over 25% were related to entanglement in or ingestion of fishery gear or marine debris, making entanglement the top anthropogenic reason for rescue during this time. Fishing gear, primarily trap lines and monofilament fishing lines, was a factor in over 85% of these rescues. Female manatees in particular were disproportionally affected by marine debris. The Florida manatee represents an example of estuarine fauna that is subject to harm from marine debris, and continued efforts to reduce and remove marine debris from estuarine environments will benefit manatees and other estuarine species.
Sound produced by fish spawning aggregations (FSAs) permits the use of passive acoustic methods to identify the timing and location of spawning. However, difficulties in relating sound levels to abundance have impeded the use of passive acoustics to conduct quantitative assessments of biomass. Here we show that models of measured fish sound production versus independently measured fish density can be generated to estimate abundance and biomass from sound levels at FSAs. We compared sound levels produced by spawning Gulf Corvina (Cynoscion othonopterus) with simultaneous measurements of density from active acoustic surveys in the Colorado River Delta, Mexico. During the formation of FSAs, we estimated peak abundance at 1.53 to 1.55 million fish, which equated to a biomass of 2,133 to 2,145 metric tons. Sound levels ranged from 0.02 to 12,738 Pa2, with larger measurements observed on outgoing tides. The relationship between sound levels and densities was variable across the duration of surveys but stabilized during the peak spawning period after high tide to produce a linear relationship. Our results support the use of active acoustic methods to estimate density, abundance, and biomass of fish at FSAs; using appropriately scaled empirical relationships, sound levels can be used to infer these estimates.
Genetic analyses of marine population structure often find only slight geographic differentiation in species with high dispersal potential. Interpreting the significance of this slight genetic signal has been difficult because even mild genetic structure implies very limited demographic exchange between populations, but slight differentiation could also be due to sampling error. Examination of genetic isolation by distance, in which close populations are more similar than distant ones, has the potential to increase confidence in the significance of slight genetic differentiation. Simulations of one-dimensional stepping stone populations with particular larval dispersal regimes shows that isolation by distance is most obvious when comparing populations separated by 2–5 times the mean larval dispersal distance. Available data on fish and invertebrates can be calibrated with this simulation approach and suggest mean dispersal distances of 25–150 km.
Design of marine reserve systems requires an understanding of larval transport in and out of reserves, whether reserves will be self-seeding, whether they will accumulate recruits from surrounding exploited areas, and whether reserve networks can exchange recruits. Direct measurements of mean larval dispersal are needed to understand connectivity in a reserve system, but such measurements are extremely difficult. Genetic patterns of isolation by distance have the potential to add to direct measurement of larval dispersal distance and can help set the appropriate geographic scales on which marine reserve systems will function well.
Human-mediated introduction of nonnative species into coastal areas via aquaculture is one of the main pathways that can lead to biological invasions. To develop strategies to counteract invasions, it is critical to determine whether populations establishing in the wild are self-sustaining or based on repeated introductions. Invasions by the Pacific oyster (Crassostrea gigas) have been associated with the growing oyster aquaculture industry worldwide. In this study, temporal genetic variability of farmed and wild oysters from the largest enclosed bay in Ireland was assessed to reconstruct the recent biological history of the feral populations using 7 anonymous microsatellites and 7 microsatellites linked to expressed sequence tags (ESTs). There was no evidence of EST-linked markers showing footprints of selection. Allelic richness was higher in feral than in aquaculture samples (P = 0.003, paired t-test). Significant deviations from Hardy–Weinberg equilibrium due to heterozygote deficiencies were detected for almost all loci and samples, most likely explained by the presence of null alleles. Relatively high genetic differentiation was found between aquaculture and feral oysters (largest pairwise multilocus FST 0.074, P < 0.01) and between year classes of oysters from aquaculture (largest pairwise multilocus FST 0.073, P < 0.01), which was also confirmed by the strong separation of aquaculture and wild samples using Bayesian clustering approaches. A 10-fold higher effective population size (Ne) and a high number of private alleles in wild oysters suggest an established self-sustaining feral population. The wild oyster population studied appears demographically independent from the current aquaculture activities in the estuary and alternative scenarios of introduction pathways are discussed.
The Northeast Arctic cod (Gadus morhua L.: NEAC) remains the most abundant cod stock in the North Atlantic, while the catches of the partially co-occurring Norwegian coastal cod (NCC) stocks have dramatically decreased in recent years. To ensure effective management of the two stocks, it is necessary to know if the population genetic structure is associated with any pattern in the spatial dynamics or whether it is affected by any distinct environmental factors. By combining information from electronic data storage tags (DST) and molecular genetics methods with statistical tools, we have been able to associate spatial dynamics and distinct environmental factors to the two cod stocks. In general, adult NEAC migrate between deep, warm overwintering grounds and shallow summer feeding grounds where water temperatures maybe low. In contrast, NCC do not undertake large-scale seasonal migrations, show little seasonal variation in depth distribution, and experience the opposite seasonal change in temperature compared with NEAC. However, within the NCC group, some individuals did conduct longer horizontal movements than others. Even though the distances calculated in this study represent the shortest distance between release and recapture positions, they are far higher than previously reported by NCC. Distinctive depth profiles indicate that this migrant NCC have moved out of the area, passing the deep trenches outside Lofoten while more stationary NCC occupies shallower depths throughout the year. The temperature profiles also indicate that migrant and stationary NCC has occupied different areas during the year. We demonstrate that the combination of information from DSTs and molecular genetics offers a deeper understanding of individual cod behaviour, provides an insight in the spatial dynamics of the species, and ultimately, improves the scientific basis for management of a complex mixed fishery of Atlantic cod.