International Council for the Exploration of the Sea
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Interim Report of the Working Group on Data Poor Diadromous Fish (WGDAM)

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posted on 2017-03-27, 00:00 authored by ICESICES
The Working Group on Data Poor Diadromous Fish (WGDAM), a subgroup of the Work-ing Group on the Science Requirements to Support Conservation, Restoration and Man-agement of Diadromous Species (WGRECORDS), started working in autumn 2015. The main task of WGDAM is to update the status and distribution knowledge of poorly un-derstood diadromous fish species for ICES. Diadromous fish are species that have sepa-rate feeding and reproduction areas in saline and fresh water and migrate between them.In 2005 the ICES Diadromous Fish Committee published a report on diadromous fish species (ICES CM 2005/I:02 Ref. ACFM, ACE, G) to report on the status and distribution of recognized poorly understood species. Since the 2005 report, there have been increas-ing legal drivers to protect and restore these species mainly for biodiversity reasons. These legal drivers and associated science have further highlighted knowledge gaps in the biology of these species. Pressure from development in freshwater, transitional and marine zones continues to threaten the life cycle of these species. More scientific infor-mation is required for these data poor diadromous species.The main threats to diadromous fish are the same as in the previous reporting period: migration barriers (e.g., dams), river construction, inputs to the rivers, lagoons and estu-aries (pollution, eutrophication and acidification), habitat loss and overfishing, for exam-ple. Many of the diadromous species are still in great difficulty, including the European sturgeon, allis and twaite shad, European eel, river lamprey, and natural stocks of migra-tory whitefish as well as coastal grayling in the Baltic Sea. Differences between areas and populations are large, e.g., sea trout in some areas are in great danger, but not in other areas. Species that have reproduction cycles dependent on rivers are threatened due to high human pressure applied to coastal areas and riverine habitats, including incompati-ble land use for the purposes of the forestry and agriculture.Since the previous reporting period, more data has been collected and knowledge has increased for some species, particularly those species that have been the focus of ICES working groups (eels, lampreys and sea trout). WGDAM work raises the need for better data on other migratory species living in the transition zone of fresh and marine envi-ronment, such as unique populations of thin lip grey mullet, smelt, whitefish and coastal grayling


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