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| 2. |
- Cardinale, Massimiliano
(författare)
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Rebuilding Mediterranean fisheries: a new paradigm for ecological sustainability
- 2013
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Ingår i: Fish and Fisheries. - : Wiley. - 1467-2960 .- 1467-2979. ; 14, s. 89-109
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Tidskriftsartikel (refereegranskat)abstract
- In Mediterranean European countries, 85% of the assessed stocks are currently overfished compared to a maximum sustainable yield reference value (MSY) while populations of many commercial species are characterized by truncated size- and age-structures. Rebuilding the size- and age-structure of exploited populations is a management objective that combines single species targets such as MSY with specific goals of the ecosystem approach to fisheries management (EAF), preserving community size-structure and the ecological role of different species. Here, we show that under the current fishing regime, stock productivity and fleet profitability are generally impaired by a combination of high fishing mortality and inadequate selectivity patterns. For most of the stocks analysed, a simple reduction in the current fishing mortality (Fcur) towards an MSY reference value (FMSY), without any change in the fishing selectivity, will allow neither stock biomass nor fisheries yield and revenue to be maximized. On the contrary, management targets can be achieved only through a radical change in fisheries selectivity. Shifting the size of first capture towards the size at which fish cohorts achieve their maximum biomass, the so-called optimal length, would produce on average between two and three times higher economic yields and much higher biomass at sea for the exploited stocks. Moreover, it would contribute to restore marine ecosystem structure and resilience to enhance ecosystem services such as reservoirs of biodiversity and functioning food webs.
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| 3. |
- Friedman, Kim, et al.
(författare)
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Management of sea cucumber stocks : patterns of vulnerability and recovery of sea cucumber stocks impacted by fishing
- 2011
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Ingår i: Fish and Fisheries. - : Wiley. - 1467-2960 .- 1467-2979. ; 12:1, s. 75-93
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Tidskriftsartikel (refereegranskat)abstract
- Identifying rates of change in the abundance of sea cucumbers under differing management regimes is fundamental to estimating commercial yields, identifying ecological interactions and facilitating management. Here, we review the status of sea cucumber stocks from a range of Pacific Island countries (Samoa, Tonga, Palau, Fiji and Papua New Guinea), some of which have had a moratorium on exports for up to a decade. We use a time-series approach to look at variation in sea cucumber presence, coverage and density from survey and re-survey data. Results give an appreciation of variation between 'high' status (less impacted) and depleted stocks. Survey data show marked declines in coverage and abundance as a result of artisanal fishing activity, and although species groups were not lost at a country level, local extirpation and range restriction was noted. Resilience and 'recovery' following cessation of fishing varied greatly, both among locations and among the species targeted. Worryingly, even after extended periods of moratorium, the density of some species was markedly low. In many cases, the densities were too low for commercial fishing, and may be at a level where the effective population size is constrained due to 'Allee' affects. From these results, we suggest that management regimes presently employed are generally not well aligned with the level of response to fishing mortality that can be expected from sea cucumber stocks. New adaptive, precautionary approaches to management are suggested, which would allow more timely interventions to be made, while refined information on stock dynamics is sought.
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| 6. |
- Piccolo, John J, 1964-, et al.
(författare)
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Conservation of endemic landlocked salmonids in regulated rivers : a case-study from Lake Vänern, Sweden
- 2012
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Ingår i: Fish and Fisheries. - : Wiley. - 1467-2960 .- 1467-2979. ; 13:4, s. 418-433
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Tidskriftsartikel (refereegranskat)abstract
- Conservation of migratory salmonids requires understanding their ecology at multiple scales, combined with assessing anthropogenic impacts. We present a case-study from over 100 years of data for the endemic landlocked Atlantic salmon (Salmo salar, Salmonidae) and brown trout (Salmo trutta, Salmonidae) in Lake Vänern, Sweden. We use this case-study to develop life history-based research and monitoring priorities for migratory salmonids. In Vänern, small wild populations of salmon and trout remain only in the heavily regulated Rivers Klar (Klarälven) and Gullspång (Gullspångsälven), and commercial and sport fisheries are maintained by hatchery stocking. These populations represent some of the last remaining large-bodied (up to 20 kg) landlocked salmon stocks worldwide. We found that one of four stocks of wild fish has increased since 1996; the other three remain critically low. Hatchery return rates for three of four stocks appear stable at roughly 1% and annual fisheries catch is roughly 75 metric tons, with an estimated 7.5% of hatchery smolts being recruited to the fishery; this also appears relatively stable since 1990. Our analysis reveals much uncertainty in key data requirements, including both river return and fisheries catch rates, estimates of wild smolt production and survival, and hatchery breeding and genetics protocols. These uncertainties, coupled with a lack of information on their riverine and lacustrine ecology, preclude effective management of these unique populations. We conclude with a framework for a life history-based approach to research and monitoring for Vänern salmon and trout, which should be applicable for all endemic, migratory salmonid populations.
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| 7. |
- Sjöstedt, Martin, 1977
(författare)
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Horizontal and vertical resource dilemmas in natural resource management: the case of African fisheries
- 2013
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Ingår i: Fish and Fisheries. - : Wiley. - 1467-2960 .- 1467-2979. ; 14:4, s. 616-624
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Tidskriftsartikel (refereegranskat)abstract
- Abstract The world’s fisheries are under severe pressure. Yet, according to the marine trophic index, the health and stability of marine ecosystems vary greatly across countries. The argument developed and tested in this article holds that some of the sources of this variation can potentially be derived from differences in the character of two fundamental relationships in society – a horizontal one between resource users and a vertical relationship between the government and the resource users. The empirical analysis focuses on sub-Saharan Africa and finds that levels of ethnic and linguistic heterogeneity and levels of democracy in the year that each country declared its exclusive economic zone have a close relationship with ensuing marine exploitation patterns.
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| 8. |
- Alexander, Steven M., et al.
(författare)
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Social ties explain catch portfolios of small-scale fishers in the Caribbean
- 2020
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Ingår i: Fish and Fisheries. - : Wiley. - 1467-2960 .- 1467-2979. ; 21:1, s. 120-131
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Tidskriftsartikel (refereegranskat)abstract
- Small-scale fisheries often involve weak management regimes with limited top-down enforcement of rules and minimal support from legal institutions, making them useful model systems for investigating the role of social influence in determining economic and environmental outcomes. In such regimes, interpersonal relationships are expected to have a strong effect on a fisher's catch portfolio, the set of fish species targeted by an individual fisher. Here, we test three competing hypotheses about social influence using belief propagation network models and show that a peer-to-peer information-sharing social network is key to explaining catch portfolios at a small-scale fishery in Jamaica. We find that experience dictates the direction of influence among fishers in the social network, with older fishers and information brokers having distinct roles in shaping catch patterns for large- and small-sized fish species, respectively. These findings highlight concrete opportunities for harnessing social networks in natural resource management. Our new approach to modelling social influence is applicable to many social-ecological systems with minimal legal and institutional support or those that rely heavily on bottom-up participatory processes.
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| 9. |
- Ammar, Yosr, et al.
(författare)
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Quantifying socio-economic novelty in fisheries social-ecological systems
- 2022
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Ingår i: Fish and Fisheries. - : Wiley. - 1467-2960 .- 1467-2979. ; 23:2, s. 445-461
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Tidskriftsartikel (refereegranskat)abstract
- Socio-economic development has shaped fisheries social-ecological systems (SES) worldwide across different scales. No work has yet undertaken how this development led to novel, not experienced before, systems structure in marine SES. Here, we quantify socio-economic novelty as the degree of dissimilarity relative to a specific spatiotemporal baseline in the Baltic Sea fisheries SES between 1975 and 2015. We used catch by "gears," catch by "commercial groups" and trade ("import" and "export") as respective indicators of novelty at national, regional and international governance levels. We found that socio-economic novelty increased over time nonlinearly in relation to the 1975–1979 baseline. The contribution to total novelty shifted from the dominance of “gears” and “commercial groups” in the late 1990s and early 2000s to “import” and “export” after the mid-2000s, i.e. from national and regional levels to the international level. The fastest increase in novelty occurred with the trade dominance shift, primarily related to monetary value rather than quantity. Spatially, novelty emerged with a large difference across countries, and a major contribution by Sweden, Denmark and Poland. We identified the influence of different management interventions and governance actions on the emergence of novelty in the Baltic SES. The decreasing socio-economic novelty at national and regional levels could indicate reduced variability due to management intervention in recent years which might decrease SES resilience to shocks. Calculating socio-economic novelty and studying its drivers at different scales could provide a better understanding of SES complexity and inform urgently needed adaptation and transformation towards sustainable future pathways.
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| 10. |
- Boonstra, Wiebren J., et al.
(författare)
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Classifying fishers' behaviour. An invitation to fishing styles
- 2016
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Ingår i: Fish and Fisheries. - : Wiley. - 1467-2960 .- 1467-2979. ; 17:1, s. 78-100
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Tidskriftsartikel (refereegranskat)abstract
- The study and classification of fishers’ behaviour remains a much debated topic. There is a tension between detailed empirical studies, which highlight the variety and diversity of fisheries, and the parsimony and generalization required to satisfy science and policy demands. This study contributes to this debate. The first sec- tion reviews quantitative methods currently used for classifying fishing practices. The review uncovers significant weaknesses in quantitative classification methods, which, we argue, can be improved through the complementary use of qualitative methods. To this purpose, we introduce the concept of ‘fishing style’, which integrates quantitative classification methods with qualitative analysis. We explain the scientific premises of the fishing-style concept, outline a general methodological framework and present a fishing-style analysis of Swedish Baltic Sea fisheries. Based on these results, we conclude that it is possible to classify fishing practices in a rel- atively uniform and limited number of styles that can highlight the rich, empirical diversity of fishers’ behaviour. We therefore propose that fishing-style analysis, based on an integration of quantitative and qualitative methods, can be an impor- tant step towards more effective and sustainable fisheries management.
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