Demonstrating the practical impact of publications in Aquatic Conservation – The case of crucian carp Carassius carassius in the East of England

1. The contribution of nearly three decades of research, much of it published in Aquatic Conservation: Marine and Freshwater Ecosystems (AQC), to the conservation of the crucian carp Carassius carassius in the East of England, including work coordinated by the Norfolk Crucian Project, is summarized.
2. Although recent genetic studies indicate that this species was probably introduced to England about the same time as common carp Cyprinus carpio, the crucian carp is considered a cultural heritage species worthy of conservation in eastern England.
3. This research covers the environmental biology of the species in the East of England, documentation of the species' decline in the county of Norfolk, and the pond management practices implemented in Norfolk to rehabilitate existing and fully terrestrialized pond habitat specifically for crucian carp conservation.
4. The AQC papers that contributed to this line of research showed that England offers a particularly favourable environment for crucian carp growth and reproduction. These AQC articles provided the evidence base to complement crucian carp conservation initiatives in the London area (mainly the counties of Essex and Hertfordshire), as well as forming the basis for the designation of crucian carp as a Biodiversity Action Priority species in the county of Norfolk.
5. The broader impact of the work in the East of England was to inspire the recently‐formed English National Crucian Conservation Project, which aims to promote the conservation of crucian carp and its habitat, and to encourage the development of well‐managed crucian fisheries.
6. These evidence‐based conservation initiatives, perhaps the first throughout Europe, have witnessed a reversal of the species' fortunes in England, which is effectively an ideal geographical region in which to promote the conservation of this species within a wider, European context.

     

A simple approach for assigning the conservation status of freshwater fish based on their natural variability – a case study from the Iberian Ecoregion

A simple, non‐lethal method for assigning conservation status is proposed based on three conservation classes (favourable, unfavourable/inadequate and unfavourable/bad) to fish species based on their natural population variability. To demonstrate this approach, conservation classes were allocated to three native fish species (brown trout Salmo trutta L., northern Iberian chub Squalius carolitertii (Doadrio), and northern straight‐mouth nase, Pseudochondrostoma duriense (Coelho) based on basic population variables (density and biomass) using a 9‐year dataset (2004–2012) from 15 different sampling sites in Spain. The classification of the population variables into conservation classes was made using previously described nonparametric methods and percentiles categorisation, and the current conservation status of the studied species was established. Temporal trend analyses showed that S. carolitertii experienced a progressive significant decrease during the study period, whereas both S. trutta and P. duriense exhibited weak increases in density. The study exemplifies the need to quantify the natural variability of fish resources to reveal their current conservation status and to determine whether short‐term and long‐term management actions are needed to rehabilitate native fish assemblages. The proposed approach could easily be employed by fisheries managers to monitor the conservational status of other native species.     

Sawfishes in The Gambia and Senegal – shifting baselines over 40 years

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Conservation of fish communities: Extending the ‘research life cycle’ by achieving practical effects

1. This article highlights the practical impact of our 2018 Aquatic Conservation: Marine and Freshwater Ecosystems publication, ‘Importance of peripheral basins: Implications for the conservation of fish assemblages’, which described fish communities in a Polish river.
2. Data on the fish assemblages of the Dniester River (Black Sea basin) are scarce; however, evidence indicates that the assemblages have declined. In our 2018 study, we hypothesized that the peripheral basin (the small basin on the edge) of the larger Upper Dniester River basin (the Strwi?? River) could maintain good ecological status and contained unique fish assemblages.
3. To examine the influence of historical factors and assess the role of peripheral basins on fish conservation, data from the Strwi?? basin were compared with the adjacent but unconnected Wiar basin (the Vistula basin; Baltic Sea basin). The Strwi?? River fish assemblages featured higher species richness and a greater number of native Ponto–Caspian species that function near the edge of their ranges.
4. This article focuses on four impacts of the 2018 publication: increasing awareness by various groups and organizations of the unique character of the surveyed river basin; highlighting important issues in assessing the ecological status of European rivers; driving the red‐listing of species and the development of stream fish conservation strategies; and identifying possible future impacts.
5. Our 2018 publication demonstrated the value of studying peripheral basins, which may affect conservation strategy development and encourage study of the importance of other peripheral basins and their role in aquatic resources conservation. Our article influenced the interpretation of fish‐based biotic indices and the conduct of monitoring work and its evaluation. It also strongly emphasized the native origin of the racer goby (Babka gymnotrachelus) in the Strwi?? River, which was important for subsequent works seeking to change the legal status of the species in Poland.

     

A review and meta‐analysis of growth and life‐history traits of a declining European freshwater fish,crucian carp Carassius carassius

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The Fraser River plume: some preliminary observations on the distribution of juvenile salmon, herring, and their prey

Zooplankton and fish densities in the southern Strait of Georgia were observed to coincide with variations in surface salinities resulting from the outflow of the Fraser River. Vertical net hauls in the euphotic zone revealed that copepods, amphipods, and euphausiids were significantly more abundant per m³ in the brackish estuarine plume (surface salinities - 10–15 ppt) when compared to the area covered by the freshwater of the Fraser River plume (0–10 ppt) and the region of the Strait of Georgia (25–30 ppt) unaffected by the outflow of the Fraser River.
The estuarine and riverine plumes had significantly higher fish densities (adult and juvenile herring, and juvenile salmonids [excluding chinook]) than the Strait of Georgia region, with no significant differences in densities of juvenile chinook salmon observed between regions. The highest catches of juvenile salmonids were at the boundary between the estuarine plume and the Strait of Georgia. Zooplankton found in the stomach contents of both adult and juvenile herring suggested that the herring were filter-feeding on the zooplankton in the estuarine plume. Juvenile salmonids fed primarily on small unidentifiable juvenile fish. The existence of increased densities of prey items in the estuarine plume is proposed to be the primary mechanism resulting in increased residence time in this region by outmigrating juvenile salmonids. Utilization of aggregated zooplankton could lead to increased salmonid growth rates and therefore to enhanced survival of individuals utilizing the Fraser River plume environment.     

The invertebrate community of the Peak–Speedwell cave system,Derbyshire, England — pressures and considerations for conservation management

1. The freshwater ecology of cave ecosystems has been poorly studied when compared with surface (epigean) systems. Most subterranean communities are typified by low abundance and low diversity of fauna due to the absence of primary production and other readily available organic carbon sources. 2. The macroinvertebrate community within the inter‐connected Peak–Speedwell cave system in the English Peak District was examined over a 2‐year period. The communities found in the surface streams which supply recharge to the Speedwell Cavern stream, and the communities in the three springs which discharge water from the cave system, were also examined. 3. Changes in the community were strongly associated with seasonal variations and natural hydrological variability. Spatial patterns within the caves reflect differences in water sources (sinking streams or percolation water) and in the ability of the organisms to survive and move through subterranean environments. 4. The majority of taxa recorded within the caves were also found at the surface either in the sinking streams or in the springs. 5. Threats to cave geo‐ecosystems, including quarrying, agriculture, waste disposal, groundwater abstraction and tourism/recreation, are examined and discussed in relation to the management and conservation of subterranean environments. Copyright © 2000 John Wiley & Sons, Ltd.     

Conservation implications of establishment success of the Critically Endangered Twee River redfin ‘Pseudobarbus’ erubescens (Skelton, ) in an artificial impoundment in South Africa

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Status of galaxiid fishes in Tasmania,Australia: conservation listings,threats and management issues

• 1. Fish of the family Galaxiidae are restricted to the southern hemisphere where they occupy a diverse array of habitats ranging from over 2000 m in elevation to sea level. Some species are diadromous and, hence, freshwater, estuarine and marine habitats are used during their life‐cycle; other species complete their entire life‐cycles in freshwater environments.
• 2. Tasmania has a diverse galaxiid fauna that accounts for 64% of native freshwater fish species found on the island. The Tasmanian galaxiid fauna is characterized by high species richness (5 genera and 16 species), endemism (11 species), restricted distributions, and non‐diadromous life histories (11 species).
• 3. The galaxiid fauna of Tasmania has significant conservation status with 69% of species considered ‘threatened’. The conservation status of the fauna is recognized at State, national and international levels.
• 4. The key threats to galaxiids in Tasmania are exotic species, hydrological manipulations, restricted distributions, general habitat degradation and exploitation of stocks.
• 5. Although work has recently been undertaken to conserve and manage Tasmanian galaxiid populations, the fauna is still thought to be imperilled. Knowledge gaps that need to be addressed include the biology and ecology of most species (e.g. reproductive biology, life histories, habitat use and requirements) and impacts of habitat manipulations, as well as mechanisms and impacts of interactions with exotic species. Techniques to monitor accurately the status of galaxiid species and their populations need to be developed and the coexistence of some galaxiids with introduced salmonids should also be examined.

Copyright © 2005 John Wiley & Sons, Ltd.     

The future of fish passage science,engineering, and practice

Much effort has been devoted to developing, constructing and refining fish passage facilities to enable target species to pass barriers on fluvial systems, and yet, fishway science, engineering and practice remain imperfect. In this review, 17 experts from different fish passage research fields (i.e., biology, ecology, physiology, ecohydraulics, engineering) and from different continents (i.e., North and South America, Europe, Africa, Australia) identified knowledge gaps and provided a roadmap for research priorities and technical developments. Once dominated by an engineering‐focused approach, fishway science today involves a wide range of disciplines from fish behaviour to socioeconomics to complex modelling of passage prioritization options in river networks. River barrier impacts on fish migration and dispersal are currently better understood than historically, but basic ecological knowledge underpinning the need for effective fish passage in many regions of the world, including in biodiversity hotspots (e.g., equatorial Africa, South‐East Asia), remains largely unknown. Designing efficient fishways, with minimal passage delay and post‐passage impacts, requires adaptive management and continued innovation. While the use of fishways in river restoration demands a transition towards fish passage at the community scale, advances in selective fishways are also needed to manage invasive fish colonization. Because of the erroneous view in some literature and communities of practice that fish passage is largely a proven technology, improved international collaboration, information sharing, method standardization and multidisciplinary training are needed. Further development of regional expertise is needed in South America, Asia and Africa where hydropower dams are currently being planned and constructed.     

Piscine reovirus in wild and farmed salmonids in British Columbia,Canada: 1974–2013

Piscine reovirus (PRV) was common among wild and farmed salmonids in British Columbia, western Canada, from 1987 to 2013. Salmonid tissues tested for PRV by real‐time rRT‐PCR included sections from archived paraffin blocks from 1974 to 2008 (n = 363) and fresh‐frozen hearts from 2013 (n = 916). The earliest PRV‐positive sample was from a wild‐source steelhead trout, Oncorhynchus mykiss (Walbaum), from 1977. By histopathology (n = 404), no fish had lesions diagnostic for heart and skeletal muscle inflammation (HSMI). In some groups, lymphohistiocytic endocarditis affected a greater proportion of fish with PRV than fish without PRV, but the range of Ct values among affected fish was within the range of Ct values among unaffected fish. Also, fish with the lowest PRV Ct values (18.4–21.7) lacked endocarditis or any other consistent lesion. From 1987 to 1994, the proportion of PRV positives was not significantly different between farmed Atlantic salmon, Salmo salar L. (44% of 48), and wild‐source salmonids (31% of 45). In 2013, the proportion of PRV positives was not significantly different between wild coho salmon, Oncorhynchus kisutch (Walbaum), sampled from British Columbia (5.0% of 60) or the reference region, Alaska, USA (10% of 58).     

Decadal trends in abundance,size and condition of Antarctic toothfish in McMurdo Sound,Antarctica, 1972–2011

We report the analyses of a dataset spanning 39 years of near‐annual fishing for Dissostichus mawsoni in McMurdo Sound, Antarctica, 1972–2011. Data on total length, condition and catch per unit effort (CPUE) were derived from the > 5500 fish caught, the large majority of which were measured, tagged and released. Contrary to expectation, the length frequency of the McMurdo Sound catch was dominated by fish in the upper two‐thirds of the overall distribution exhibited in the industrial catch for the Ross Sea shelf. Fish length and condition increased from the early 1970s to the early 1990s and then decreased. Fish length positively correlated with Ross Sea ice extent in early spring, a relationship possibly caused by more ice encouraging larger fish to move farther south over the shelf and into the study area. Fish condition positively correlated with the amount of open water in the Ross Sea during the previous summer (Feb), perhaps reflecting greater availability of prey with the higher productivity that more open water brings. Decreasing fish size corresponds to the onset of the fishery, which targets the large individuals. CPUE was constant through 2001 and then decreased dramatically. We hypothesize that this decrease is related to the industrial fishery, which began in the 1996–97 austral summer, and concentrates effort over the ice‐free Ross Sea continental slope. As a result of limited prey choices and close coupling among mesopredators of the region, Antarctic toothfish included, the fishery appears to be dramatically altering the trophic structure of the Ross Sea.     

Surveillance of selected nutrients,additives and undesirables in commercial Norwegian fish feeds in the years 2000–2010

This article presents data on commercial, Norwegian fish feeds from 2000 to 2010, including elements, additives, some selected vitamins and a range of environmental contaminants. Iodine, selenium and vitamin D concentrations, all declined during the time period; simultaneously, a reduction in marine ingredients in feeds has occurred. Still, the feeds fulfilled known fish nutrient requirements. Arsenic (As) in the feed was fitted with a polynomial regression with peak concentrations in 2004, correlating with fishery landings of blue whiting (Micromesistus poutassou), a reduction species with high content of As. A polynomial regression was also significant for mercury, which peaked in 2005 and was correlated to fish meal (FM) inclusion in the feeds. Residues of the pesticide DDT and its metabolites, chlordane and toxaphene, as well as polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers and sum dioxins and dioxin‐like PCBs, all decreased during this time period. These positive changes in undesirable substances can likely be attributed to the increasing replacement of marine ingredients with plant ingredients, as well as the increased use of South American fish oils rather than North Atlantic ones. On the other hand, cadmium concentrations were twofold higher in South American FMs, and increased in feeds from 2000 to 2010.     

Spatial and temporal variation in fish community structure and diversity in the largest tropical flood‐pulse system of South‐East Asia

The Tonle Sap River and Lake (TSRL) is South‐East Asia's largest tropical flood pulse with a flow‐reversal system that supports one of the world's largest freshwater fisheries. However, among the world's tropical floodplains, the resources of the TSRL have received little ecological research. Here, we described the spatiotemporal TSRL fish diversity and community variation using daily records from 2012 to 2015 on fish abundance from six sites covering the TSRL system. We found that high fish diversity occurred in sites located in the middle of Tonle Sap Lake, and the lowest diversity was observed in the southern section. The spatial abundance distribution patterns displayed a river–lake gradient, with three fish assemblages that were clustered based on their composition similarities and were characterised by 96 indicator species. In the southern section, fish assemblages were characterised by longitudinal migratory fishes; in contrast, in the middle system, fish assemblages were represented by species with combined ecological attributes (i.e. longitudinal and lateral migratory species and floodplain residents). Towards the northern section, fish assemblages were composed of lateral migratory and floodplain resident species. Species richness and abundance peaked at approximately 2–2.5 and 4 months, respectively, after the peak flow in early October, during which Tonle Sap River resumes its normal flow direction (outflow). This suggests that seasonal flood pulses (i.e. rising and falling water levels) play a pivotal role in structuring spatiotemporal variation in the TSRL fish assemblages. Our study has implications for fisheries monitoring and conservation initiatives.     

Biodiversity and rarity distributions of native freshwater fish in an agricultural landscape: the importance of β diversity between and within water‐body types

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Diversity of fish and fisheries from the Lake Encantada Environmental Protection Area,Ilhéus,Brazil

• 1. Lake Encantada, in the basin of the Almada River (Bahia State), has an area of 650.5 ha and a perimeter of 13.3 km. In 1993, an area of 11 800 ha around the lake was designated an Environmental Protection Area (Class V category). The main goal of this study was to identify fish species in the lake and to determine possible threats to their conservation.
• 2. Fish samples were obtained with gillnets between May 2002 and February 2004, and used to calculate indices of species diversity Shannon (H′), richness (d) and evenness (J′).
• 3. Eleven fish species comprising nine families were collected during the sampling period. Three introduced species occurred in the lake: Prochilodus argenteus, endemic to the São Francisco river basin, and two African species, Oreochromis niloticus and Clarias gariepinus. In overall ranking, Prochilodus argenteus was first in number of individuals (46%) and weight (59%), followed by Genidens genidens in numbers (31%), and Clarias gariepinus in weight (15%).
• 4. The occurrence and dominance of introduced species is discussed as well as their possible impacts on the trophic structure of this ecosystem.

Copyright © 2007 John Wiley & Sons, Ltd.     

Integrating local ecological knowledge,citizen science and long‐term historical data for endangered species conservation: Additional records of angel sharks (Chondrichthyes: Squatinidae) in the Mediterranean Sea

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Riverine connectivity,upstream influences,and multi‐taxa representation in a conservation area network for the fishes of Michigan,USA

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The status and distribution of a newly identified endemic galaxiid in the eastern Cape Fold Ecoregion,of South Africa

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