title: Survey of river and sea lampreys in German waters of the Baltic Sea - basis of successful rebuilding programmes
Creators: name: Thiel, R.
name: Winkler, H. M.
name: Riel, P.
name: Neumann, R.
Publisher: name: ASC 2005 - W - Theme session
Year: 2024
Subjects: Fisheries and aquaculture
Pressures, impacts, conservation, and management

description: No abstracts are to be cited without prior reference to the author.In order to prepeare population rebuilding programmes, the status of river lamprey and sea lamprey was investigated within the German waters of the Baltic Sea. From August 2003 until August 2005 the following sources of data were analysed: (i) research fisheries with otter and shrimp trawls, (ii) records from commercial and recreational fisheries, (iii) records from ichthyological museum collections, (iv) commercial catch statistics and relevant publications. 317 records of river lampreys with 19,977,622 individuals and 89 records of sea lampreys with 129 individuals were obtained for the period from 1649 - 2005. The number of recorded individuals of river lampreys per year was two times higher from 1649 - 1939 than in the following period 1940 - 1989. Only 1 % of the yearly records of river lampreys from this time period was estimated from 1990 - 2005. No distinct trend of the temporal population development of sea lamprey was found. From 1829 - 1989 the highest number of records of sea lamprey (70 %) was estimated for subdivisions 22 and 24. From 1990 - 2005 all records of sea lamprey in German Baltic waters were distributed within the coastal waters and estuaries. Areas with distinct higher densities of sea lamprey records were not estimated. Most of the records of river lamprey (88 %) originated from subdivisions 24 and 26 from 1649-1989. The species was mainly distributed within the Szczecin Lagoon and adjacent waters, the lower Vistula River, the Vistula Lagoon, the Bay of Gdańsk and the Curonian Lagoon. From 1990 - 2005 most of the records (83 %) and recorded individuals (98 %) of river lamprey from German Baltic waters originated from the Szczecin Lagoon and its adjacent waters. 9 Spawning sites of river lamprey were found in the river systems of Peene, Warnow and Stepenitz. Regular annual spawning of river lamprey occurs not at all spawning sites. Actual reproduction of sea lamprey is not known from rivers of the German Baltic Sea area. From 1887-1999 about 14,377 kilogram of river lampreys were caught annually in the southern Baltic Sea. 82 % of the total lamprey catches of the southern Baltic Sea originated from subdivision 26. Highest lamprey catches were obtained during the decades from 1890 -1919. The contribution of the lower Vistula River, Vistula Lagoon and Bay of Gdańsk increased remarkable from 1887-1939, whereas the importance of the Szczecin Lagoon and adjacent waters for the lamprey fishery decreased during the same period of time. A remarkable proportion of lamprey catches is contributed from the region of the Curonian Lagoon since 1950. However, the critical situation for the populations of river lamprey in both marine and freshwater habitats of the German Baltic Sea area requires a rebuilding programme for the still existing but threatened populations.