Fishery-seal interactions in Irish waters: Current perspectives and future research priorities

Interactions between seals and the fishing industry are an on-going problem in Ireland and indeed globally across the range of most seal species. These interactions occur at both the operational (seal damage to catches and fishing gear) and biological (competition for shared resources) level. With declines in fish stocks there has been increased interest in the extent of competition for resources between commercial fisheries and seals. High levels of seal damage perceived by the fishing industry has led to frequent calls for seal culls, highlighting the significance of the problem. However, the scale of interaction between seals and commercial fishing and aquaculture in Ireland heretofore remained unclear. A comprehensive review of existing data, augmented with data from key stakeholders on the current state of play is presented to provide a realistic and representative account of the situation. This suggests that seal interactions with commercial fisheries in Ireland are most significant in inshore (<12 nautical miles from shore) static-net (or passive) fisheries (e.g. gill/tangle nets) and have increased following the driftnet ban in 2006, which suggests displacement of seal interactions from salmon to other fisheries. The industry highlighted pollack, angler fish, cod, and turbot fisheries as the main inshore fisheries currently impacted by operational damage to gear and catch by seals. Seal damage to line-caught salmon continues, with industry feedback suggesting large geographical variation in the range of damage levels reported. Salmon farming installations are also increasingly being targeted by seals, with significant losses due to seal depredation being reported. In the absence of robust data on seal depredation, the extent to which changes in fishing gear and practices have reduced damage levels, or resulted in displacement of seal foraging effort, is unknown. Recommendations are made to suggest how research efforts should be focused to address critical data gaps identified in the study.     

On the potential impact of harbour seal predation on the cod population in the eastern North Sea

Increasing Scandinavian harbour seal populations during the last decades coincide in time with the collapse of the cod fishery. Assumptions of a causal relationship have led to claims favouring re-introduction of seal hunting. Proposals for ‘adaptive management’ often assume that decimating seal populations will automatically favour the fishery. This argument presupposes seal predation to be sufficiently large to have a measurable impact on the fish population. The potential magnitude of the cod-seal interaction was analysed using data on harbour seal abundance, feeding habits and compiled information on cod life history and cod landing statistics. A size-structured life history matrix for the cod population was applied and the size-specific prey preferences of harbour seals were taken into account. Estimated seal predation was small compared to both the landings by the fishery, and to minimum estimates of the total cod population. Furthermore, since the size classes of cod targeted by seals have low reproductive values, the impact of seal predation on cod production will be further reduced. Our analyses suggest harbour seals have a negligible impact on the cod fishery.     

Swedish coastal fisheries—From conflict mitigation to participatory management

Several research projects have studied Swedish coastal fishery to investigate the conflict between seals and fishery. In recent years, a strategy of participation by means of co-management has been unfolding. Realising that maintaining the coastal fishery requires societal support and knowledge integration, attempts have been made to introduce the principle of participatory management into the centralised Swedish fisheries management system. However, this co-management approach, presently implemented in six pilot projects, will take a long time to develop through a sustained process of experimentation and improvement.     

Dietary analysis of harbour seals (Phoca vitulina) from faecal samples and overlap with fisheries in Erimo,Japan

The number of harbour seals in Japan has been rebounding since protection began in the mid‐1980s. With the increase in seal numbers, increased conflict with fisheries has occurred through depredation and the belief that seals compete with fisheries for prey. However, competition can only be determined if the prey species and quantities seals consume over time are known. We studied the diet of harbour seals in Erimo, site of the largest population of harbour seals in Japan, from 2011 to 2012 and assessed the degree of prey overlap with local fisheries. We used both hard parts and DNA techniques to identify prey items in seal scats, and compared these results to local fisheries data. A total of 46 prey occurrences was detected by both methods, of which 17 matched between techniques at least to the family level. Hard parts methods identified five incidences of prey undetected by DNA methods in five scats (one incidence per scat). DNA methods identified 24 additional prey occurrences in 13 scats, for which no hard part evidence for that prey had been found. This more than doubled the total number of prey occurrences across the 15 scats compared. Overall, the most frequently occurring harbour seal prey were walleye pollock (Theragra chalcogramma), sculpins and snailfishes. In contrast, the top three groups targeted by fisheries were codfishes, salmon and invertebrates. Many species common in the harbour seal's diet such as snailfishes and blennies were not targeted by fisheries. Fishes such as greenlings, sculpins, rockfishes and Japanese anchovy (Engraulis japonicus) were common in the diet of harbour seals, but made up a very small proportion of fisheries catches in Erimo. The importance of other prey species varied between seasons. Sculpins, greenlings and forage fishes were the top three prey groups for harbour seals in spring by percent modified frequency of occurrence, whereas the most important target groups by percentage mass caught by fisheries were codfishes, cephalopods and other invertebrates. Sculpins and rockfishes remained as important prey items for harbour seals in summer and autumn, in addition to codfishes, snailfishes and blennies. In contrast, the main groups caught by fisheries in summer were other fishes, particularly Japanese amberjack (Seriola quinqueradiata) and various species of sharks and eels, and invertebrates. By autumn, Erimo fisheries had focussed on catching salmon. Salmon were taken by harbour seals as well during this period, but at a relatively lower frequency compared to other prey groups. The results of our study show that although harbour seals consumed several of the prey species targeted by fisheries, the relative importance of these species to seals and fisheries and the seasons in which they were targeted were different.     

Co-existence of seals and fisheries? Adaptation of a coastal fishery for recovery of the Baltic grey seal

A complex controversy emerged when the grey seal population in the Baltic Sea recovered after decades of stagnation. The seals now cause substantial economic losses to coastal fisheries. The paper analyses the attempts taken in Finland to mitigate the problems of fishermen. The mitigation attempts include the hunting of seals, fishing technology development, economic compensations and more comprehensive management approaches. These measures are discussed in light of the long-term sustainability and adaptability of a coastal fishery. This question is important with respect to further discussions on the possibility of the coastal fishery’s co-existence with seals and sheds light on more general goals for the adaptability in the management of social–ecological systems. The paper concludes that the more comprehensive measures taken have acknowledged the need to enhance the fishery’s adaptability, but the managerial approach they represent falls short of the requirements for successful adaptive management, especially in terms of embedding the management into specific coastal contexts.     

The paradox of fairness: The impact of escalating complexity on fishery management

In the US and Canada, a commitment to fairness leads to overly complex management regimes that contribute to overexploitation. We illustrate the pattern of increasing complexity in the Scotia/Fundy groundfish fishery in Atlantic Canada, the New England groundfish fishery and the Fraser River salmon fishery in British Columbia, all of which have collapsed or declined in recent years. Increasing complexity proceeds inexorably in publicly managed fisheries. However, the alternatives of transferring ownership to individual fishers or fishing communities appear not to be viable solutions. Rather, we suggest a co-management approach which may be unfair to some fishers but will greatly reduce the pressure to overfish.     

Participatory assessment of management measures for octopus vulgaris pot and trap fishery from southern Portugal

Co-management has shown promising results for the sustainable use of fishery resources. The common octopus (Octopus vulgaris) pot and trap fishery in the Algarve (Portugal) holds the potential for implementation of a co-management system. To explore this potential, seven participatory workshops took place between 2014–2015, bringing together 60 participants from 10 fishing associations and 16 fisheries management and research institutions. The exercise resulted in promising outcomes with regards to the possible implementation of a co-management system for the fishery. In the present work an overview of the outcomes of the participatory workshops is given and compared with initiatives worldwide. Among the management actions identified, some have direct impacts on the octopus’ life cycle, while all target the same overall objective: to regulate fishing effort. In the informal setting of the workshops, a formal request was developed: the establishment of an annual closed season in the Algarve. This request was taken into consideration by the responsible management institution.     

Seals and fisheries in South Africa — competition and conflict

There are two types of interactions between seals and commercial fisheries in South Africa: biological (potential competition for shared resources between the two "predators") and operational (conflicts during fishing operations). Using data for the 1980s, a comparison is made of relative consumption by different predators in South African waters. Seals and fisheries are not the major consumers in the system, but they do take comparable amounts. This has resulted in calls for a reduction in the seal population, but to date, no studies have shown that reducing seal predation of commercial species will make more fish available for the fisheries. Most fisheries are subject to some form of operational interaction with seals. These interactions include consumption of catches (operational consumption), disturbance of fishing operations (operational disturbance) and damage to fishing gear (operational gear damage); they vary in degree of severity, both seasonally and regionally. Estimates of the consumption by seals from fishing operations in South Africa show it to be a minimal percentage of fishery catches and a small proportion of the total predation by seals. Preliminary calculations of overall economic losses resulting from seal interference show this to be small in comparison with the wholesale value of the catches. Seals die as a result of fishing operations, and estimates of the potential mortality through entanglement, drowning and deliberate killing indicate this mortality to be of a magnitude that should be monitored.     

Prioritising range-wide scientific monitoring of the Cape fur seal in southern Africa

The range of the Cape fur seal Arctocephalus pusillus pusillus population largely coincides with the region of the cold, nutrient-rich Benguela Current Large Marine Ecosystem (BCLME) adjoining the west coast of South Africa, Namibia and Angola. Range-wide scientific monitoring of the seal population was initiated in the 1970s to inform on population management questions related to commercial seal harvesting and seal–fishery interactions. Since the 1970s, seal-related management goals have changed, especially in South Africa where seal harvesting ceased in 1990 and government has conformed to scientific advice against the culling of seals for the intended benefit of fisheries. However, renewed impetus has been provided to seal research and monitoring through the expansion of the ‘ecosystem-based management’ concept in the region, as well as improved international cooperation in the management of marine resources. Together with wide-scale ecosystem changes in the marine environment, and forecast effects of global climate changes, this has justified the continuation and improvement of range-wide scientific monitoring of Cape fur seals. We prioritised seal monitoring based on cost, effort, and relevance to monitoring objectives that have been identified for the region, with consideration given to the conservation status of top predators, interspecific and predator-fishery interactions and the potential use of Cape fur seals as indicators of ecosystem health. An integrated approach incorporating a suite of life-history attributes of seals is recommended, useful monitoring tools are discussed and the need for coordinated monitoring effort and standardisation of sampling techniques is emphasised.     

Collaborative fisheries management in the Northeast US: Emerging initiatives and future directions

The nature of participation by fishing organizations in fisheries management in the Northeast US is changing. Evidence of this is the number of groups that are actively seeking opportunities for group governance of marine resources. This article explores emerging collaborative or co-management arrangements in this region (a process whereby decision-making is shared between federal/council level and fishery stakeholder groups) and the shift towards an ecosystem-based approach to the management of marine fisheries.This research suggests that it is an opportune time for the development of a regional policy in the Northeast that provides an enabling environment in support of decentralized governance of federally managed marine fisheries. It also suggests that these initiatives can play a key role in operationalizing ecosystem-based management.     

On the potential impact of harbour seal predation on the cod population in the eastern North Sea

Increasing Scandinavian harbour seal populations during the last decades coincide in time with the collapse of the cod fishery. Assumptions of a causal relationship have led to claims favouring re-introduction of seal hunting. Proposals for ‘adaptive management’ often assume that decimating seal populations will automatically favour the fishery. This argument presupposes seal predation to be sufficiently large to have a measurable impact on the fish population. The potential magnitude of the cod-seal interaction was analysed using data on harbour seal abundance, feeding habits and compiled information on cod life history and cod landing statistics. A size-structured life history matrix for the cod population was applied and the size-specific prey preferences of harbour seals were taken into account. Estimated seal predation was small compared to both the landings by the fishery, and to minimum estimates of the total cod population. Furthermore, since the size classes of cod targeted by seals have low reproductive values, the impact of seal predation on cod production will be further reduced. Our analyses suggest harbour seals have a negligible impact on the cod fishery.     

Dispersion and feeding of larval herring (Clupea harengus L.) in the Moray Firth during September 1985

A plume of herring larvae dispersing from a spawning site at Clythness in the Moray Firth (northern Scotland) was surveyed during early September 1985. Several cohorts of larvae were evident from the length distributions, and these were arranged in order of increasing length (age) towards the south-west. The spacing of cohort centres indicated a drift rate of 1–2 km day⁻¹.Calanoid copepod nauplii constituted the major proportion of the diet of larvae <10 mm sampled during the study. Cyclopoid copepod nauplii and gastropod veligers were not found in the diet although they were present in the water. The distribution of nauplii in the region was inversely correlated with the concentration of phytoplankton chlorophyll, and nauplii concentrations were above average in the vicinity of the herring spawning site. The drift trajectory of the herring larvae took them towards an area of high copepodite and adult copepod concentration—items which formed an increasing part of the diet of larger (older) larvae.     

Addressing multiple goals of ecosystem approach through deliberation and technology development

This paper studies two participatory processes to manage the interactions between seals and coastal fishing in Finland. One was a deliberative multi-stakeholder process, in which the stakeholders in a region approached the problem solving by joint problem definition. The other process was a technology development project to reduce the damage by seals and seal by-catch. This paper discusses the contribution of the processes to maintain economic viability of the coastal fishery without jeopardising the conservation of seals. It concludes that both processes address important aspects of maintaining a dynamic stability in a socio-ecological system of coastal fishing, but a combination of the approaches would better allow dealing with the problem's political aspects and fishing practices that are intertwined in various ways.     

A note on the economics of Swedish Baltic Sea fisheries

The cod stocks in the Baltic Sea are important not only for fisheries but for the entire ecosystem utilized by numerous stakeholders around the coast. All such activities have economic values. In this note the economics of the Swedish Baltic Sea cod fishery is estimated in relation to the sector's interaction with other users of the Baltic Sea ecosystem. The results show a negative resource rent for the fishery, € −5 million without public expenses (subsidies and administrative costs), and € −13 million including public expenses. The interactions between the fisheries and tourism, seal population, carbon dioxide emissions, recreational fishing, and discards are discussed, and when monetary estimates are available these are related to the estimated resource rent.     

Resolving environmental issues in the southern Brazilian artisanal penaeid-trawl fishery through adaptive co-management

Many conventional management strategies have been demonstrated to be ineffective in achieving sustainable fisheries, and new approaches are required to overcome existing environmental, social and economic problems. Adaptive co-management represents the combination of a learning-by-doing approach (adaptive management) involving all related and legitimate stakeholders in the decision-making process (collaborative management). In this study, the relevant experiences from a fishery in southern Brazil are reported. The first section of the paper summarizes the broad history of national fisheries and their management. Then the southern Brazilian artisanal penaeid-trawl fishery is briefly described and the three main problems associated with the common gears used are discussed, including their (1) poor size and species selectivities, (2) poor efficiencies, and (3) their mechanical impacts on benthic habitats. Finally, a framework is proposed to address the environmental and socio-economic issues in the fishery and its implementation discussed via an adaptive co-management approach.     

Fishery cooperatives in Cuba: Potential benefits,legal feasibility,and governance pre-conditions

Currently there is a strong interest in Cuba in improving the performance of the fisheries sector with respect to social, biological, and economic outcomes. Many important fishery resources appear to be overexploited, and previous fishery regulations have had mixed success in restoring fishery stocks. The current fishing pressure could also have adverse impacts on other valuable ecosystem services that support economic activities such as dive tourism and recreational fishing. A new State policy to expand cooperative enterprises to non-agricultural sectors provides an opportunity for fishery cooperatives to be created for the first time since the early years of the Cuban Revolution. This paper explores the potential ecological, social, and economic benefits of adopting fishery cooperatives as a co-management scheme for Cuba's marine fisheries. It concludes that well-designed fishery cooperatives can offer substantial benefits to the management of the fishery sector. Based on an analysis of the relative success of fishing cooperatives worldwide, guidelines are provided for the design of fishery cooperatives in Cuba.     

Heterogeneous management and conservation perceptions within the gooseneck barnacle co-management system in Asturias (N. Spain)

Stakeholders’ perceptions can influence the success of a fishery. It is important to take these perceptions into account when evaluating the development of a management system and its conservation policies. Structured questionnaires were used to determine fishers’ management and conservation perceptions of the Asturian gooseneck barnacle co-management system. Perceptions were analyzed for the entire fishery and for different socioeconomic factors, these were: location, age, years in the management system, way of access, alternative income sources and income. Fishers’ perceptions varied widely among socioeconomic factors. In fact, a trade-off between management and conservation perceptions was observed for the different categories within each socioeconomic factor, particularly for the years in the management system, location and income factors. Despite the heterogeneity in perceptions, the co-management system has successfully generated a strong conservation ethic in its resource users. Furthermore, as a group, gooseneck barnacle fishers hold positive perceptions on the performance of the management system. When generating management policies, fisheries’ managers must take the heterogeneity of resource users present in the fishery into account. The gooseneck barnacle co-management system demonstrates that even within the same fishery there can be multiple paths to sustainability.     

Unfinished business: Taiwan's experience with rights-based coastal fisheries management

This paper examines a case involving a mix of Territorial Use Rights in Fisheries, co-management and the competition for using coastal zones. In the 2000s, Taiwan's government initiated a remodeling of the fishery right system, which is a rights-based approach to fisheries management, as an attempt to address conflicts between fishers and developers regarding the use of coastal space and to put community-based co-management into practice. The paper particularly compares the system before and after 2000 and identifies areas of concern in the implementation of the remodeled system. The results show that the government's support for this system signifies progress in the right direction. However, concerns emerge, mostly involving fishers' low participation, fishermen's association's lack of technical skills and financial resources, and the division of management responsibility. The government is advised to play a more active role in dealing with these concerns. Finally, the paper reveals that the factor of competition for using coastal zones poses a challenge to co-management, and suggests a holistic view with integrated coastal management or marine spatial planning practices, for developing co-management under the fishery right system.     

Transfer of lipids from plankton to blubber of harp and hooded seals off East Greenland

Sub-Arctic marine ecosystems are some of the most productive ecosystems in the world's oceans. The capacity of herbivorous zooplankton, such as Calanus, to biosynthesize and store large amounts of lipids during the short and intense spring bloom is a fundamental adaptation which facilitates the large production in these ecosystems. These energy-rich lipids are rapidly transferred through the food chain to Arctic seals. The fatty acids and stable isotopes from harp seal (Phoca groenlandica) and hooded seal (Cystophora cristata) off East Greenland as well as their potential prey, were analysed. The results were used to describe the lipid dynamics and energy transfer in parts of the East Greenland ecosystem. Even if the two seal species showed considerable overlap in diet and occurred at relatively similar trophic levels, the fatty acid profiles indicated that the bases of the food chains of harp and hooded seals were different. The fatty acids of harp seals originate from diatom-based food chain, whereas the fatty acids of hooded seals originate from dinoflagellate and the prymnesiophyte Phaeocystis pouchetii-based food chain. Stable isotope analyses showed that both species are true carnivores on the top of their food chains, with hooded seal being slightly higher on the food chain than harp seal.     

Local permit ownership in Alaska salmon fisheries

Changes in ownership of limited entry permits by “local” residents of the region where a fishery occurs may have significant economic and social implications for fishery-dependent regions. This paper examines changes in local permit ownership in Alaska salmon fisheries, for which a long-term decline in rural local permit ownership is an important policy concern. Theoretically, permit markets allocate permits over time to the individuals who are willing to pay the most for them. Any factors that differentially affect what local and non-local residents are willing to pay for permits may affect the equilibrium share of permits held by local residents. For remote rural fisheries in particular, these may include differences between local and non-local residents with respect to access to and costs of financing permits and boats, costs of travel to the fishery, opportunity costs of participation in the fishery, and many other factors. As a fishery increases in profitability, differences between local and non-local residents in access to financing matter more while differences in costs of travel and opportunity costs matter less in the relative ranking of what local and non-local residents are willing to pay for permits. This tends to increase the share of non-local residents among buyers willing to pay the market price for permits, reducing the equilibrium share of permits held by local residents. This leads to a conflict between two important policy goals: increasing fishery profitability and maintaining rural local permit ownership. Consistent with predictions of this theory, the local share of permit ownership in Alaska salmon fisheries is negatively related to permit prices (an indicator of fishery profitability).