| 1. |
- Aas, O., et al.
(författare)
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Salmonid stocking in five North Atlantic jurisdictions: Identifying drivers and barriers to policy change
- 2018
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Ingår i: Aquatic Conservation-Marine and Freshwater Ecosystems. - : Wiley. - 1052-7613. ; 28:6, s. 1451-1464
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Tidskriftsartikel (refereegranskat)abstract
- New knowledge challenges long-established practices of fish stocking and transfer because of increasing scientific consensus that the release of cultivated fish can pose risks to biodiversity; however, stocking can also improve fisheries, creating difficult decision trade-offs regarding its use. Accordingly, controversy persists about fish stocking and transfer. No studies, however, have embraced a multinational perspective to understand the important governance dimensions of the success and failure of salmonid stocking and transfer policies. The present study has analysed the historical development and contemporary governance of the stocking and transfer of native and non-native salmonids of the genera Salmo, Salvelinus, and Oncorhynchus in five legislative units around the North Atlantic Ocean: the Atlantic Provinces of Canada, France, Germany, Norway, and Sweden. The study is based on the analyses of published and unpublished literature, and a survey of experts. Current salmonid stocking policies and practices varied significantly among jurisdictions; the degree of policy change varied, from radical and rapid changes de jure and de facto in Atlantic Canada and Norway to incremental mostly de jure changes in France and Germany. Rapid policy change in Atlantic Canada, Norway, and partly in Sweden can be explained by the socio-political importance of salmonid fisheries, stocking regulations based on policy objectives to conserve wild Atlantic salmon (Salmo salar), well-documented examples of the harmful consequences of transfers of non-native species, and well-developed vertical governance linkages. The policy changes resemble that of the 'punctuated equilibrium policy framework'. By contrast, France and Germany place less socio-political emphasis on salmonids, have stocking regulations less directed at wild salmonids, more local-level decision making, more species-rich fish communities, and little evidence of adverse ecological impacts of the transfer and stocking of salmonids. This has led to small, incremental changes in stocking policy de facto that are reflective of the 'advocacy coalition policy framework'.
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| 2. |
- Alexander, Steven M., et al.
(författare)
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Examining horizontal and vertical social ties to achieve social-ecological fit in an emerging marine reserve network
- 2017
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Ingår i: Aquatic conservation. - : Wiley. - 1052-7613 .- 1099-0755. ; 27:6, s. 1209-1223
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Tidskriftsartikel (refereegranskat)abstract
- Most MPA networks are designed only with ecological processes in mind to increase their conservation utility. However, since MPA networks often involve large geographic areas, they also affect and involve multiple actors, institutions, and policy sectors. A key challenge when establishing an effective MPA network is to align the social system' with the biophysical MPA network (the ecological system'). This challenge is often denoted as social-ecological fit'. Facilitating collaborative social interactions among various actors and stakeholders (social connectivity) is equally as important as accomplishing ecological connectivity. New analytical approaches are required to effectively examine this social' dimension of fit. An emerging marine reserve network in Jamaica and the recent invasion of Indo-Pacific lionfish are used as a case study to: (1) examine the extent to which horizontal and vertical social ties bring local and national actors together to collaborate, coordinate, and share knowledge; and (2) assess the extent to which different attributes and features of such multilevel social networks may enhance or inhibit particular aspects of social-ecological fit. Findings suggest that multilevel linkages have played the greatest role in relation to enhancing fit in the marine reserve network in the context of the recent lionfish invasion. However, the long-term propensity of the multi-actor and multilevel networks to enhance social-ecological fit is uncertain given the prevalence of weak social ties, lack of a culture of information sharing and collaboration, and limited financial resources.
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| 3. |
- Arvidsson, Björn L, 1952-, et al.
(författare)
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Recruitment of the threatened mussel Margaritifera margaritifera in relation to mussel population size, mussel density and host density
- 2012
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Ingår i: Aquatic conservation. - Malden, MA : John Wiley & Sons. - 1052-7613 .- 1099-0755. ; 22, s. 526-532
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Tidskriftsartikel (refereegranskat)abstract
- Anthropogenic, abiotic factors are considered main causes of recruitment failure of unionid mussels, including the freshwater pearl mussel (Margaritifera margaritifera). In this large-scale investigation, we instead examined the relationship between biotic factors and mussel recruitment.Juvenile mussel density was positively related to both mussel population size and density of which the last appeared to be a more accurate measure of recruitment.Host fish density of young-of-the-year and older brown trout (Salmo trutta) were positively related to recruitment. Moreover, the mean density of both age classes of fish, when grouped into density classes was positively related to juvenile mussel density, an effect that decreased at trout densities above 10 trout 100 m-2.There was a higher relative importance of mussel population size and density than trout density to recruitment.To increase recruitment of juvenile mussels, managers may apply measures that increase mussel density, and trout density up to about 10 trout 100 m-2 in connection to mussel beds. Mussel beds may also be managed and one possible measure within small and sparse mussel populations may be to concentrate the remaining mussels to areas where trout density is high. Likewise, young-of-the-year trout may also be moved to areas of high mussel density, as young trout individuals are relatively resident during their first year. This may increase mussel larval infection rates and mussel recruitment.
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| 4. |
- Boström, C., et al.
(författare)
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Distribution, structure and function of Nordic eelgrass (Zostera marina) ecosystems: Implications for coastal management and conservation
- 2014
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Ingår i: Aquatic conservation. - : Wiley. - 1052-7613. ; 24:3, s. 410-434
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Forskningsöversikt (refereegranskat)abstract
- This paper focuses on the marine foundation eelgrass species, Zostera marina, along a gradient from the northern Baltic Sea to the north-east Atlantic. This vast region supports a minimum of 1480km2 eelgrass (maximum >2100km2), which corresponds to more than four times the previously quantified area of eelgrass in Western Europe. Eelgrass meadows in the low salinity Baltic Sea support the highest diversity (4-6 spp.) of angiosperms overall, but eelgrass productivity is low (<2g dw m-2 d-1) and meadows are isolated and genetically impoverished. Higher salinity areas support monospecific meadows, with higher productivity (3-10g dw m-2 d-1) and greater genetic connectivity. The salinity gradient further imposes functional differences in biodiversity and food webs, in particular a decline in number, but increase in biomass of mesograzers in the Baltic. Significant declines in eelgrass depth limits and areal cover are documented, particularly in regions experiencing high human pressure. The failure of eelgrass to re-establish itself in affected areas, despite nutrient reductions and improved water quality, signals complex recovery trajectories and calls for much greater conservation effort to protect existing meadows. The knowledge base for Nordic eelgrass meadows is broad and sufficient to establish monitoring objectives across nine national borders. Nevertheless, ensuring awareness of their vulnerability remains challenging. Given the areal extent of Nordic eelgrass systems and the ecosystem services they provide, it is crucial to further develop incentives for protecting them. © 2014 The Authors.
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| 5. |
- Burdett, Heidi L.
(författare)
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Looking forward in aquatic conservation
- 2024
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Ingår i: Aquatic conservation. - : John Wiley & Sons. - 1052-7613 .- 1099-0755. ; 34:2
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 6. |
- Carlén, Ida, 1976-, et al.
(författare)
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High-frequency pingers do not increase catch loss owing to seals in the Baltic Sea
- 2023
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Ingår i: Aquatic conservation. - : Wiley. - 1052-7613 .- 1099-0755. ; 33:4, s. 389-396
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Tidskriftsartikel (refereegranskat)abstract
- The Baltic Proper harbour porpoise population is listed as Critically Endangered by IUCN, and only a few hundred animals remain. One of the most serious threats to this population is bycatch in static net fisheries. To minimize bycatch, ICES has proposed that acoustic deterrent devices, pingers, should be used on static nets within the population’s range.However, there have previously been indications that grey seals learn to associate the pinger sounds with the presence of nets with easily accessible prey, and that pinger use therefore can increase the risk of seal depredation in static net fisheries.In recent years, pingers operating at higher frequencies have been made commercially available, the idea being that harbour porpoises will still be able to hear the sound at 50–120 kHz while this will be above or at the limit of seal hearing. This would mean that such high-frequency pingers would not induce this so-called dinner-bell effect.In this study, data were collected from active commercial static net fisheries in the Baltic Proper, using two types of high-frequency pingers operating at 50–120 and 70 kHz, respectively. Pingers were attached to nets in accordance with manufacturers’ guidelines, and fishers were asked to estimate the catch loss owing to seals in nets with and without pingers.Data were received from 646 deployments made between May 2019 and September 2020. Four generalized mixed effect models were developed with relevant variables.The results suggest using high-frequency pingers does not increase seal depredation on static nets. It is concluded that pingers could be used as an interim measure to minimize bycatch of the Critically Endangered Baltic Proper harbour porpoise population.
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| 7. |
- Cooke, Steven J., et al.
(författare)
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Stewardship and management of freshwater ecosystems : From Leopold's land ethic to a freshwater ethic
- 2021
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Ingår i: Aquatic conservation. - : John Wiley & Sons. - 1052-7613 .- 1099-0755. ; 31, s. 1499-1511
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Tidskriftsartikel (refereegranskat)abstract
- 1. In 1949, Aldo Leopold formalized the concept of the 'land ethic', in what emerged as a foundational and transformational way of thinking about natural resource management, biodiversity conservation, and stewardship in terrestrial systems. Yet, the land ethic has inherent linkages to aquatic ecosystems; Leopold himself conducted research on rivers and lakes, and freshwater ecosystems figured widely in his writing. 2. We reflect on the land ethic and other aspects of Leopold's scholarship to identify key messages that provide insight into the stewardship and management of freshwater ecosystems around the globe. We also frame what we call the 'freshwater ethic' around Leopold's legacy. Although Leopold could not have envisaged the stressors affecting modern aquatic ecosystems, his core principles remain salient. These apply not only to ecosystem protection, but also to the ethics of modern conservation economics, sustainability, and the protection of natural capital, in which lakes, rivers, and wetlands now figure prominently. 3. We identify key 'Aldo-inspired' recommendations for protecting and restoring freshwater ecosystems in the Anthropocene that emanate directly from his writings (e.g. adopt an ecosystem approach, identify win-win-win scenarios, recognize the irreplaceability of wild waters, and strive for freshwater optimism). 4. In an epoch where links between people and nature are becoming more explicit in environmental management, policy, and governance, we suggest that Aldo Leopold's work illustrates how inspirational, seminal thinkers have offered leadership in this domain. We contend that today there is still much that can be learned from Leopold, especially by the next generation of environmental practitioners, to ensure the effective stewardship of our aquatic ecosystems. 5. We submit that the adoption of a freshwater ethic in parallel with Leopold's land ethic will enhance the stewardship of the world's increasingly threatened fresh waters by raising the profile of the plight of fresh waters and identifying enduring actions that, if embraced, will help conserve and restore biodiversity.
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| 8. |
- Croll, Donald A., et al.
(författare)
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Vulnerabilities and fisheries impacts : the uncertain future of manta and devil rays
- 2016
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Ingår i: Aquatic conservation. - : Wiley. - 1052-7613 .- 1099-0755. ; 26:3, s. 562-575
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Forskningsöversikt (refereegranskat)abstract
- 1. Manta and devil rays of the subfamily Mobulinae (mobulids) are rarely studied, large, pelagic elasmobranchs, with all eight of well-evaluated species listed on the IUCN Red List as threatened or near threatened. 2. Mobulids have life history characteristics (matrotrophic reproduction, extremely low fecundity, and delayed age of first reproduction) that make them exceptionally susceptible to overexploitation. 3. Targeted and bycatch mortality from fisheries is a globally important and increasing threat, and targeted fisheries are incentivized by the high value of the global trade in mobulid gill plates. 4. Fisheries bycatch of mobulids is substantial in tuna purse seine fisheries. 5. Thirteen fisheries in 12 countries specifically targeting mobulids, and 30 fisheries in 23 countries with mobulid bycatch were identified. 6. Aside from a few recently enacted national restrictions on capture, there is no comprehensive monitoring, assessment or control of mobulid fisheries or bycatch. Recent listing through the Convention on the International Trade in Endangered Species (CITES) may benefit mobulids of the genus Manta (manta rays), but none of the mobulids in the genus Mobula (devil rays) are protected. 7. The relative economic costs of catch mitigation are minimal, particularly compared with a broad range of other, more complicated, marine conservation issues. Copyright (C) 2015 John Wiley & Sons, Ltd.
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| 9. |
- Dannewitz, Johan, et al.
(författare)
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Colonization history and human translocations explain the population genetic structure of the noble crayfish (Astacus astacus) in Fennoscandia: Implications for the management of a critically endangered species
- 2021
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Ingår i: Aquatic Conservation: Marine And Freshwaterecosystems. - : Wiley. - 1052-7613 .- 1099-0755. ; 31, s. 1970-1982
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Tidskriftsartikel (refereegranskat)abstract
- The noble crayfish (Astacus astacus) is an endangered freshwater species in Europe. The main threat is from lethal crayfish plague, caused by the oomycete Aphanomyces astaci that has been spread over Europe by introduced North American crayfish species, acting as chronic carriers of the disease. Most of the remaining noble crayfish populations are found in the Baltic Sea area, and there is an urgent need to implement conservation actions to slow down or halt the extinction rate in this region. However, limited knowledge about the genetic structure of populations in this area has so far precluded the development of conservation strategies that take genetic aspects into consideration. Key objectives of this large-scale genetic study, covering 77 locations mainly from northern Europe, were to describe the contemporary population genetic structure of the noble crayfish in the Fennoscandian peninsula (Sweden, Norway, and Finland), taking postglacial colonization history into account, and to evaluate how human activities such as stocking have affected the genetic structure of the populations. Analyses of 15 microsatellite markers revealed three main genetic clusters corresponding to populations in northern, middle, and southern Fennoscandia, with measures of genetic diversity being markedly higher within populations in the southern cluster. The observed genetic structure probably mirrors two main colonizations of the Baltic Sea basin after the last glaciation period. At the same time, several deviations from this pattern were observed, reflecting past human translocations of noble crayfish. The results are discussed in relation to the conservation and management of this critically endangered species. In particular, we recommend increased efforts to protect the few remaining noble crayfish populations in southern Fennoscandia and the use of genetic information when planning stocking activities, such as reintroductions following local extinctions.
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| 10. |
- Degerman, Erik, et al.
(författare)
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Predicting population status of freshwater pearl mussel (Margaritifera margaritifera, L.) in central Sweden using instream and riparian zone land-use data
- 2013
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Ingår i: Aquatic Conservation: Marine and Freshwater Ecosystems. - : Wiley. - 1052-7613 .- 1099-0755. ; 23, s. 332-342
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Tidskriftsartikel (refereegranskat)abstract
- The freshwater pearl mussel Margaritifera margaritifera (L.) has become scarce and threatened throughout most of its distribution range, and is consequently listed as endangered' by the IUCN. It has been suggested and used as an indicator species and even as an umbrella species. Despite this, few studies have examined factors affecting its catchment-level population status. This work tested the hypothesis that it is possible to predict freshwater pearl mussel population viability (reproducing/not reproducing) and population status in central Sweden from a combination of geospatial data describing riparian land-cover and use, water chemistry data, and electrofishing data describing the abundance of the host fish species (brown trout, Salmo trutta) in 56 streams. Mussel population viability was best predicted by total phosphorus. Using higher-resolution data (six classes) on mussel population status, host fish abundance (0+ trout) was the best predictor. At abundances below 5 0+ trout per 100m2 and above a concentration of 8 mu gL1 total phosphorus, only three viable populations existed. Geospatial data could be used to predict levels of total phosphorus and thereby indirectly to predict mussel viability. Geospatial data could not be used to predict abundance of 0+ trout, which is thought to depend more on instream factors. This study demonstrates that geospatial data on riparian land-use and cover can be a useful tool for screening waters potentially harbouring non-reproducing mussel populations. Copyright (c) 2013 John Wiley & Sons, Ltd.
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