Browsing by Subject "FISHERIES"

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  • Lai, Tin-Yu; Salminen, Jani; Jäppinen, Jukka-Pekka; Koljonen, Saija; Mononen, Laura; Nieminen, Emmi; Vihervaara, Petteri; Oinonen, Soile (2018)
    In this paper, we examine how progress on ecosystem service indicators could contribute to ecosystem accounting within the scope of environmental-economic accounting in Finland. We propose an integration framework and examine the integration of ecosystem service indicators into environmental-economic accounting with two case studies relevant for Finland: (1) water-related ecosystem services and (2) the ecosystem services of fish provisioning in marine ecosystems. In light of these case studies, we evaluate the relevance of existing Finnish ecosystem service indicators, the data availability for ecosystem accounting in Finland, and the applicability of the System of Environmental-Economic Accounting o Experimental Ecosystem Accounting (SEEA-EEA) framework to integrate Finnish ecosystem service indicators and other relevant data into environmental-economic accounts. The results indicate that the present ecosystem service indicators can assist in creating a basis for ecosystem accounting, but the indicators require further elaboration to be more compatible with the existing environmental-economic accounting system.
  • Perälä, Tommi; Vanhatalo, Jarno; Chrysafi, Anna (2020)
    Expert assessments are routinely used to inform management and other decision making. However, often these assessments contain considerable biases and uncertainties for which reason they should be calibrated if possible. Moreover, coherently combining multiple expert assessments into one estimate poses a long-standing problem in statistics since modeling expert knowledge is often difficult. Here, we present a hierarchical Bayesian model for expert calibration in a task of estimating a continuous univariate parameter. The model allows experts' biases to vary as a function of the true value of the parameter and according to the expert's background. We follow the fully Bayesian approach (the so-called supra-Bayesian approach) and model experts' bias functions explicitly using hierarchical Gaussian processes. We show how to use calibration data to infer the experts' observation models with the use of bias functions and to calculate the bias corrected posterior distributions for an unknown system parameter of interest. We demonstrate and test our model and methods with simulated data and a real case study on data-limited fisheries stock assessment. The case study results show that experts' biases vary with respect to the true system parameter value and that the calibration of the expert assessments improves the inference compared to using uncalibrated expert assessments or a vague uniform guess. Moreover, the bias functions in the real case study show important differences between the reliability of alternative experts. The model and methods presented here can be also straightforwardly applied to other applications than our case study.
  • Momigliano, Paolo; Jokinen, Henri; Calboli, Federico; Aro, Eero; Merilä, Juha (2019)
    Unobserved diversity, such as undetected genetic structure or the presence of cryptic species, is of concern for the conservation and management of global biodiversity in the face of threatening anthropogenic processes. For instance, unobserved diversity can lead to overestimation of maximum sustainable yields and therefore to overharvesting of the more vulnerable stock components within unrecognized mixed-stock fisheries. We used DNA from archival (otolith) samples to reconstruct the temporal (1976-2011) genetic makeup of two mixed-stock flounder fisheries in the angstrom land Sea (AS) and the Gulf of Finland (GoF). Both fisheries have hitherto been managed as a single stock of European flounders (Platichthys flesus), but were recently revealed to target two closely related species: the pelagic-spawning P. flesus and the newly described, demersal-spawning P. solemdali. While the AS and GoF fisheries were assumed to consist exclusively of P. solemdali, P. flesus dominated the GoF flounder assemblage (87% of total) in 1983, had disappeared (0%) by 1993, and remained in low proportions (10%-11%) thereafter. In the AS, P. solemdali dominated throughout the sampling period (>70%), and P. flesus remained in very low proportions after 1983. The disappearance of P. flesus from the GoF coincides in time with a dramatic (similar to 60%) decline in commercial landings and worsening environmental conditions in P. flesus' northernmost spawning ground, the Eastern Gotland Basin, in the preceding 4-6 years. These results are compatible with the hypothesis that P. flesus in the GoF is a sink population relying on larval subsidies from southern spawning grounds and the cause of their disappearance is a cessation of larval supply. Our results highlight the importance of uncovering unobserved genetic diversity and studying spatiotemporal changes in the relative contribution of different stock components, as well as the underlying environmental causes, to manage marine resources in the age of rapid anthropogenic change.
  • Saulamo, Kari; Heikinheimo, Outi; Lappalainen, Jyrki (2020)
    In the Archipelago Sea, pikeperch (Sander lucioperca) is an important species in both commercial and recreational fisheries. Pikeperch is caught mainly with small mesh size gillnets, and annual fishing mortality is high. The possible effects of such fisheries, as well as temperature or density on pikeperch growth have not been studied earlier. The first hypothesis of this study was that the effect of temperature on growth is positive and that of density is negative. The second hypothesis was that size selectivity of gillnets causes the fast-growing individuals to be caught at younger ages than the slow growing ones. The results showed that temperature had a significant positive effect on growth, and this was greater than the negative effect of year-class density, which was also significant. The gillnet selectivity caused a difference of up to 60mm in back-calculated lengths in the fully recruited age groups within the same year class, between pikeperch caught at age 6+ and age 9+. Thus, the Rosa Lee phenomenon caused by gillnet size-selectivity led to the removal of faster growing specimens from the population at younger ages. This can potentially cause underestimation of real growth, and thus, poor fishery management.
  • Rincon, Margarita M.; Catalan, Ignacio A.; Mantyniemi, Samu; Macias, Diego; Ruiz, Javier (2018)
    Many studies underscore the importance of incorporating the effect of environmental data within a life-history-stage-specific framework for determining the recruitment and survival of small pelagic fish. The recruitment of anchovy (Engraulis encrasicolus) in the Gulf of Cadiz (NE Atlantic) is sensitive to the effect of intense easterlies, stratification of the water column, and discharges from the Guadalquivir River on early life stages. As a proof of concept, we have developed the basis for a new Bayesian model with a dual time step resolution: monthly for juveniles and adults, and weekly for earlier life stages. This dual time step resolution resolves environmental effects on prerecruits while simulating the effect of fishing on recruits. Our estimates for juvenile abundances are validated with field data. The Bayesian framework accounts for the uncertainty, thus providing consistent length-frequency estimates and a plausible environmentally driven stock-recruitment relationship.
  • Jarić, Ivan; Roll, Uri; Arlinghaus, Robert; Belmaker, Jonathan; Chen, Yan; China, Victor; Douda, Karel; Essl, Franz; Jähnig, Sonja C.; Jeschke, Jonathan M.; Kalinkat, Gregor; Kalous, Lukáš; Ladle, Richard; Lennox, Robert J.; Rosa, Rui; Sbragaglia, Valerio; Sherren, Kate; Šmejkal, Marek; Soriano-Redondo, Andrea; Souza, Allan T.; Wolter, Christian; Correia, Ricardo A. (2020)
    The ongoing digital revolution in the age of big data is opening new research opportunities. Culturomics and iEcology, two emerging research areas based on the analysis of online data resources, can provide novel scientific insights and inform conservation and management efforts. To date, culturomics and iEcology have been applied primarily in the terrestrial realm. Here, we advocate for expanding such applications to the aquatic realm by providing a brief overview of these new approaches and outlining key areas in which culturomics and iEcology are likely to have the highest impact, including the management of protected areas; fisheries; flagship species identification; detection and distribution of threatened, rare, and alien species; assessment of ecosystem status and anthropogenic impacts; and social impact assessment. When deployed in the right context with awareness of potential biases, culturomics and iEcology are ripe for rapid development as low-cost research approaches based on data available from digital sources, with increasingly diverse applications for aquatic ecosystems.
  • Pihlajamäki, Mia-Elina; Asikainen, Arja; Ignatius, Suvi; Haapasaari, Päivi; Tuomisto, Jouni (2019)
    Using fish resources for food supply in a sustainable and efficient way requires an examination of the feasibility of prioritising the use of forage species. The present paper deals with the issue from the consumer perspective. Using Baltic herring as a case study, the role of sociodemographic determinants, the drivers and barriers of Baltic herring consumption are investigated in four Baltic Sea countries, based on an internet survey. The drivers and barriers of Baltic herring consumption are compared to those relating to Baltic salmon, to identify the main differences in consumer perceptions on species that are primarily used as feed and food. The present paper concludes that prioritising forage species primarily for human consumption calls for proactive catch use governance, which (1) acknowledges the species- and country-specific intricacies of forage fish consumption, (2) improves the availability of safe-to-eat fish on the market, and 3) provides consumers with sufficient information on the species (e.g., the type of herring and its origin), the sustainability of the fisheries, and the related health risks and benefits.
  • Tuomisto, Jouni; Asikainen, Arja; Meriläinen, Päivi; Haapasaari, Päivi (2020)
    Background: Health risks linked with dioxin in fish remain a complex policy issue. Fatty Baltic fish contain persistent pollutants, but they are otherwise healthy food. We studied the health benefits and risks associated with Baltic herring and salmon in four countries to identify critical uncertainties and to facilitate an evidence-based discussion. Methods: We performed an online survey investigating consumers’ fish consumption and its motivation in Denmark, Estonia, Finland, and Sweden. Dioxin and methylmercury concentrations were estimated based on Finnish studies. Exposure-response functions for several health endpoints were evaluated and quantified based on the scientific literature. We also quantified the infertility risk of men based on a recent European risk assessment estimating childhood dioxin exposure and its effect on sperm concentration later in life. Results: Baltic herring and salmon contain omega-3 fatty acids and vitamin D, and the beneficial impact of these fishes on cardiovascular diseases, mortality, and the risk of depression and cancer clearly outweighs risks of dioxins and methylmercury in people older than 45 years of age and in young men. Young women may expose their children to pollutants during pregnancy and breast feeding. This study suggests that even in this critical subgroup, the risks are small and the health benefits are greater than or at least similar to the health risks. Value of information analysis demonstrated that the remaining scientific uncertainties are not large. In contrast, there are several critical uncertainties that are inherently value judgements, such as whether exceeding the tolerable weekly intake is an adverse outcome as such; and whether or not subgroup-specific restrictions are problematic. Conclusions: The potential health risks attributable to dioxins in Baltic fish have more than halved in the past 10 years. The new risk assessment issued by the European Food Safety Authority clearly increases the fraction of the population exceeding the tolerable dioxin intake, but nonetheless, quantitative estimates of net health impacts change only marginally. Increased use of small herring (which have less pollutants) is a no-regret option. A more relevant value-based policy discussion rather than research is needed to clarify official recommendations related to dioxins in fish.
  • Haapasaari, Paivi; Ignatius, Suvi; Pihlajamaki, Mia; Sarkki, Simo; Tuomisto, Jouni; Delaney, Alyne (2019)
    This article focuses on the dioxin problem of Baltic herring and salmon fisheries and its governance that is based on natural scientific knowledge. The dioxin problem weakens the perceived quality of Baltic salmon and herring as food and affects the way the catches can be used. This influences negatively the fishing livelihood, the coastal culture, and the availability of the fish for consumers. We explored how the governance of the dioxin problem could be improved, to better address its socio-economic and cultural implications. We identified four main actions: (1) adopt environmental, economic and social sustainability, and food security and safety as shared principles between the environmental, food safety/public health, and fisheries policies, (2) establish collaboration between the environmental, public health, and fisheries sectors at the regional level, (3) enhance interaction around the dioxin problem within the fisheries sector, and (4) support the participation of the Baltic fisheries stakeholders in the EU-level food safety governance. Viewing dioxins in fish not only as a natural scientific problem but as a multidimensional one would enable a wider toolbox of governing instruments to be developed to better address the different dimensions. This would support steps towards collaborative governance and a food system approach.
  • Whitlock, Rebecca; Mäntyniemi, Samu; Palm, Stefan; Koljonen, Marja-Liisa; Dannewitz, Johan; Östergren, Johan (2018)
    1. Inferring the dynamics of populations in time and space is a central challenge in ecology. Intra-specific structure (for example genetically distinct sub-populations or meta-populations) may require methods that can jointly infer the dynamics of multiple populations. This is of particular importance for harvested species, for which management must balance utilization of productive populations with protection of weak ones. 2. Here we present a novel method for simultaneous learning about the spatio-temporal dynamics of multiple populations that combines genetic data with prior information about abundance and movement, akin to an integrated population modelling approach. We apply the Bayesian genetic mixed stock analysis to 17 wild and 10 hatchery-reared Baltic salmon (S. salar) stocks, quantifying uncertainty in stock composition in time and space, and in population dynamics parameters such as migration timing and speed. 3. The genetic data were informative about stock-specific movement patterns, updating priors for migration path, timing and speed. Use of a population dynamics model allowed robust interpolation of expected catch composition at areas and times with no genetic observations. Our results indicate that the commonly used "equal prior probabilities" assumption may not be appropriate for all mixed stock analyses: incorporation of prior information about stock abundance and movement resulted in more plausible and precise estimates of mixture compositions in time and space. 4. The model we present here forms the basis for optimizing the spatial and temporal allocation of harvest to support the management of mixed populations of migratory species.
  • Ulaş, Ali; Tunca, Sezgin; Aydin, İlker (2019)
    In this study, we analyzed social and economic dimensions of shore-based recreational fishing (RF) along Izmir Inner Bay in the Metropolitan Province Izmir of Turkey. 634 shore-based recreational fishers were interviewed via on-site face-to-face interviews during the fishing activity from January to December in 2016. Market value approach was utilized to calculate net economic values and expenses of recreational fishers along in eight coastal districts, Goztepe, Karatas, Konak, Pasaport, Alsancak, Bayrakli, Karsiyaka and Bostanli along the coast of the inner bay. The annual fishing efforts demonstrated significant differences among districts. For example; Bostanli fishers that have higher education levels with higher income spent higher time for RF but, finally, this attitude of Bostanli fishers resulted in low CPUE levels. Considering the RF experience of Bostanli fishers, they are either not likely or able to target or catch bigger or more fish. In contrast, Goztepe fishers seems much professional compared to fishers by having the highest amount of catch in shortest time compared to rest of the districts. The highest mean CPUE was observed for Goztepe, Karatas and Konak fishers even so, these CPUE amounts were much under the ones determined in previous studies in Turkey. Considering the catch composition of fishers, S. auratus was the most common catch for all fishers. Secondly, D. labrax and Mugilid species constituted the majority. High fishing related expenditures were observed in all districts, then harvesting values reached quite high levels considering the previous studies. To conclude, RF in Izmir Inner Bay of Turkey is great social and economic activity by generating increase in RF related expenditures, jobs and indirect economic activity in services sector. The results of this study provide an update information of the recreational fishers' profile to help regulate recreational fishery.
  • Cardoso, Pedro; Amponsah-Mensah, Kofi; Barreiros, João P.; Bouhuys, Jamie; Cheung, Hubert; Davies, Alisa; Kumschick, Sabrina; Longhorn, Stuart J.; Martínez-Muñoz, Carlos A.; Morcatty, Thais Q.; Peters, Gretchen; Ripple, William J.; Rivera-Téllez, Emmanuel; Stringham, Oliver C.; Toomes, Adam; Tricorache, Patricia; Fukushima, Caroline S. (2021)
    Illegal or unsustainable wildlife trade is growing at a global level, threatening the traded species and coexisting biota, and promoting the spread of invasive species. From the loss of ecosystem services to diseases transmitted from wildlife to humans, or connections with major organized crime networks and disruption of local to global economies, its ramifications are pervading our daily lives and perniciously affecting our well-being. Here we build on the manifesto 'World Scientists' Warning to Humanity, issued by the Alliance of World Scientists. As a group of researchers deeply concerned about the consequences of illegal or unsustainable wildlife trade, we review and highlight how these can negatively impact species, ecosystems, and society. We appeal for urgent action to close key knowledge gaps and regulate wildlife trade more stringently.
  • Barman, Partho Protim; Liu, Qun; Al-Mamun, Md Abdullah; Schneider, Petra; Mozumder, Mohammad Mojibul Hoque (2021)
    Stock assessment is necessary to understand the status of fishery stocks. However, for the data-poor fishery, it is very challenging to assess the stock status. The length-based Bayesian biomass (LBB) technique is one of the most powerful methods to assess the data-poor fisheries resources that need simple length frequency (LF) data. Addressing the present gap, this study aimed to assess the stock status of three sardines (Sardinella fimbriata, Dussumieria acuta, and D. elopsoides) in the Bay of Bengal (BoB), Bangladesh using the LBB method. The estimated relative biomass for S. fimbriata was B/B-0 < B-MSY/B-0, indicating the overfished biomass, while the assessed B/B-0 > B-MSY/B-0 for D. acuta and D. elopsoides indicates healthy biomass. Additionally, for S. fimbriata, the length at first landing was smaller than the optimum length at first landing (Lc < L-c_opt), indicating an overfishing status, but a safe fishing status was assessed for D. acuta and D. elopsoides (Lc > L-c_opt). Therefore, increasing the mesh size of fishing gears may help to ensure the long-term viability of sardine populations in the BoB, Bangladesh.
  • La Mere, Kelsey Maggan; Mäntyniemi, Samu; Haapasaari, Päivi (2020)
    In the Baltic Sea region, salmon are valued for the ecological, economic, and cultural benefits they provide. However, these fish are threatened due to historical overfishing, disease, and reduced access to spawning rivers. Climate change may pose another challenge for salmon management. Therefore, we conducted a problem-framing study to explore the effects climate change may have on salmon and the socio-ecological system they are embedded within. Addressing this emerging issue will require the cooperation of diverse stakeholders and the integration of their knowledge and values in a contentious management context. Therefore, we conducted this problem framing as a participatory process with stakeholders, whose mental models and questionnaire responses form the basis of this study. By framing the climate change problem in this way, we aim to provide a holistic understanding of the problem and incorporate stakeholder perspectives into the management process from an early stage to better address their concerns and establish common ground. We conclude that considering climate change is relevant for Baltic salmon management, although it may not be the most pressing threat facing these fish. Stakeholders disagree about whether climate change will harm or benefit salmon, when it will become a relevant issue in the Baltic context, and whether or not management efforts can mitigate any negative impacts climate change may have on salmon and their fishery. Nevertheless, by synthesizing the stakeholders' influence diagrams, we found 15 themes exemplifying: (1) how climate change may affect salmon, (2) goals for salmon management considering climate change, and (3) strategies for achieving those goals. Further, the stakeholders tended to focus on the riverine environment and the salmon life stages occurring therein, potentially indicating the perceived vulnerability of these life stages to climate change. Interestingly, however, the stakeholders tended to focus on traditional fishery management measures, like catch quotas, to meet their goals for these fish considering climate change. Further, social variables, like “politics,” “international cooperation,” and “employment” comprised a large proportion of the stakeholders' diagrams, demonstrating the importance of these factors for salmon management.