8 research outputs found
The Living Planet Index (LPI) for migratory freshwater fish:Technical Report
Migratory freshwater fish (i.e. fish that use freshwater systems, either partly or exclusively) occur around the world and travel between critical habitats to complete their life cycle. They are disproportionately threatened compared to other fish groups but global trends in abun-dance, regional differences and drivers of patterns have not yet been comprehensively described. Using abundance information from the Living Planet Database, we found widespread declines between 1970 and 2016 in tropical and temperate areas and across all regions, all migration categories and all populations. Globally, migratory freshwater fish have declined by an average of 76%. Average declines have been more pronounced in Europe (-93%) and Latin America & Caribbean (-84%), and least in North America (-28%). The percentage of species represented was highest in the two temperate regions of Europe and North America (almost 50%). For the continents of Africa, Asia, Oceania, and South America, data was highly deficient, and we advise against making conclusions on the status of migratory freshwater SUMMARYfish in these areas. Potamodromous fish, have declined more than fish migrating between fresh and salt water on average (-83% vs -73%). Populations that are known to be affected by threats anywhere along their migration routes show an average decline of 94% while those not threatened at the population level have increased on av-erage. Habitat degradation, alteration, and loss accounted for around a half of threats to migratory fish, while over-exploitation accounted for around one-third. Protected, regulated and exploited populations decreased less than unmanaged ones, with the most often recorded actions being related to fisheries regulations, including fishing restrictions, no-take zones, fisheries closures, bycatch reductions and stocking (these were most com-mon in North America and Europe). Recorded reasons for observed increases tended to be mostly unknown or un-described, especially in tropical regions. This information is needed to assemble a more complete picture to assess how declines in migratory freshwater fishes could be reduced or reversed. Our findings confirm that migratory freshwater fish may be more threatened throughout their range than previously documented
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Barrier Tracker - Using citizen science to build the most comprehensive atlas of barriers in Europe
There is already a substantial amount of data in existence on the barriers within European rivers. However, even for the most comprehensively audited countries, data is patchy and often of poor quality. Proper assessment and prioritisation of remedial action cannot be undertaken until the full picture is known. Barrier Tracker, part of the Adaptive Management of Barriers in European Rivers (AMBER) project, seeks to address this issue by using a smartphone app to crowd-source data from across Europe. Initially available in 9 languages the app allows anyone to record the barriers they encounter. The app has been designed to allow a low-level of minimum information to be provided in order to reduce complexity for inexperienced recorders. However, a certain sub-set of data is always required to ensure the data is still useful.
The app also features an interactive map which displays both the app generated data and all of the currently known barrier data from Europe. This means that a recorder can easily check their local area to see if the barriers they encounter have already been recorded. It also provides motivation for recorders to tackle under-recorded areas.
A specially designed citizen science web portal has also been designed to work alongside the app. Owing the fact that many thousands of records are anticipated, the portal contains a section to allow members of the public to classify the barrier data. Classification ultimately leads to verification and/or re-determination of records. Each record has to be classified a minimum number of times and with a set percentage of agreement before verification occurs. Citizen scientists can, therefore, assist with the entire life-cycle of the data.
Having only just gone live at the time of writing, in its first two weeks the app generated over 600 records of barriers from across Europe
World Fish Migration Day Connects Fish, Rivers, and People â From a OneâDay Event to a Broader Social Movement
More than one million barriers fragment Europeâs rivers
Rivers support some of Earthâs richest biodiversity1 and provide essential ecosystem services to society2, but they are often fragmented by barriers to free flow3. In Europe, attempts to quantify river connectivity have been hampered by the absence of a harmonized barrier database. Here we show that there are at least 1.2 million instream barriers in 36 European countries (with a mean density of 0.74 barriers per kilometre), 68 per cent of which are structures less than two metres in height that are often overlooked. Standardized walkover surveys along 2,715 kilometres of stream length for 147 rivers indicate that existing records underestimate barrier numbers by about 61 per cent. The highest barrier densities occur in the heavily modified rivers of central Europe and the lowest barrier densities occur in the most remote, sparsely populated alpine areas. Across Europe, the main predictors of barrier density are agricultural pressure, density of river-road crossings, extent of surface water and elevation. Relatively unfragmented rivers are still found in the Balkans, the Baltic states and parts of Scandinavia and southern Europe, but these require urgent protection from proposed dam developments. Our findings could inform the implementation of the EU Biodiversity Strategy, which aims to reconnect 25,000 kilometres of Europeâs rivers by 2030, but achieving this will require a paradigm shift in river restoration that recognizes the widespread impacts caused by small barriers
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More than one million barriers fragment Europeâs rivers
Rivers support some of Earthâs richest biodiversity and provide essential ecosystem services to society, but they are often fragmented by barriers to free flow. In Europe, attempts to quantify river connectivity have been hampered by the absence of a harmonized barrier database. Here we show that there are at least 1.2 million instream barriers in 36 European countries (with a mean density of 0.74 barriers per kilometre), 68 per cent of which are structures less than two metres in height that are often overlooked. Standardized walkover surveys along 2,715 kilometres of stream length for 147 rivers indicate that existing records underestimate barrier numbers by about 61 per cent. The highest barrier densities occur in the heavily modified rivers of central Europe and the lowest barrier densities occur in the most remote, sparsely populated alpine areas. Across Europe, the main predictors of barrier density are agricultural pressure, density of river-road crossings, extent of surface water and elevation. Relatively unfragmented rivers are still found in the Balkans, the Baltic states and parts of Scandinavia and southern Europe, but these require urgent protection from proposed dam developments. Our findings could inform the implementation of the EU Biodiversity Strategy, which aims to reconnect 25,000 kilometres of Europeâs rivers by 2030, but achieving this will require a paradigm shift in river restoration that recognizes the widespread impacts caused by small barriers