Time series of German catch data of flounder, cod and perch in the Western Baltic See (coastline off Mecklenburg-Western Pomerania) Eel monitoring

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Katherine Alexander
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1 Time series of German catch data of flounder, cod and perch in the Western Baltic See (coastline off Mecklenburg-Western Pomerania) Eel monitoring program, Reef program

2 Introduction The data set contains by-catch abundance data of flounder and perch collected during an eel monitoring program (Dorow et al. 2012), which was established in The survey design was created by dividing the Mecklenburg-Western Pomerania coastline in an eternal part of about 350 km and an internal part of about km shoreline. Altogether 9 different areas were monitored (4 areas off the coast, Wismar Bight incl. Salzhaff, north of Kühlungsborn, north and east of Rügen island and east of Usedom island; and 5 areas in internal waters, Darß-Zingst Bodden chain, Strelasund, Greifswalder Bodden, Peene river, and Stettin lagoon) This was done due to the salinity gradient from 15 PSU in the western areas to 10 PSU east off Usedom island and due to the different habitat types ranging from eposed sand-silt habitats off the coast to sheltered highly eutrophic internal waters with submerged vegetation. In the 9 areas each year 6 stations were randomly selected and monitored.

3 Monitoring sites Wismar Bight and Salzhaff North of Kühlungsborn city Northeast of Ruegen Island East of Usedom Peninsula - Darß-Zingst Bodden chain - Strelasund - Greifswalder Bodden - Peene river / Achterwasser - Stettin Lagoon

Gear system used: The fyke net system consist of an eternal leader net weir (high 1.8 m, length 100 m, mesh size 10 mm) with a fyke net chamber in each corner.

4 Gear system used: The fyke net system consist of an eternal leader net weir (high 1.8 m, length 100 m, mesh size 10 mm) with a fyke net chamber in each corner. The net square encloses a fished area of 1 ha. In addition, 6 chains of eel traps (4 double chamber fyke nets with an 8 m leader net) were placed inside the 100m 100 m net square.

5 Inde value Inde value Mean catch per haul off coast Perch area ,00 8,00 6,00 4,00 2,00 0, Flounder area ,00 80,00 60,00 40,00 20,00 0,

6 Inde value Inde value Mean catch per haul inside coastline Perch area I-V 250,00 200,00 150,00 100,00 50,00 0, Flounder area I-V 14,00 12,00 10,00 8,00 6,00 4,00 2,00 0,

7 Inde value Inde value Mean catch per haul all areas Perch area 1-V 150,00 125,00 100,00 75,00 50,00 25,00 0, Flounder area 1-V 50,00 40,00 30,00 20,00 10,00 0,

8 Species list Species Outer part (area 1-4) Inner part (area I-V) Eel pout Perch Common bream Cod Flounder Plaice Turbot European smelt Greater Sand eel Lesser Sand eel Longspined bullhead Shorthorne sculpin Ruffe Roach Pike perch Three-spined stickleback Black goby Round goby X Sand goby Lesser pipefish

9 Reef Nienhagen Used Prime gears: reason for Nienhagen reef deployment was to improve, increase, 1 Gill net: mesh or at size least 60 mm; maintain length 45 the m, fishery drop 2.4 m resources in this local area 1 Gill net: mesh size 55 mm; length 45 m, drop 2.4 m 1 Trammel net: mesh size 50/350 mm; length 50 m, drop 2.0 m 2 Nordic coastal survey nets: mesh size mm length 49 m each, drop 2.0 m 5 Eel basket chains Several Cod pots Annually 8 to 12 surveys, launching time: 24 h

4 m 1 Trammel net: mesh size 50/350 mm; length 50 m, drop 2.

10 Reef Nienhagen Used gears: 1 Gill net: mesh size 60 mm; length 45 m, drop 2.4 m 1 Gill net: mesh size 55 mm; length 45 m, drop 2.4 m 1 Trammel net: mesh size 50/350 mm; length 50 m, drop 2.0 m 2 Nordic coastal survey nets: mesh size mm length 49 m each, drop 2.0 m 5 Eel basket chains Several Cod pots Annually 8 to 12 surveys, launching time: 24 h

11 Inde value Inde value Reef Nienhagen Mean catch per haul (number per 100 m gillnets) Cod Flounder ,5 5 4,5 4 3, cod Reef Nienhagen cod Reference Börgerende 3 2,5 2 1,5 1 0,5 0 flounder Reef Nienhagen flounder Reference Börgerende

12 Inde value Inde value Reef Nienhagen Mean catch per haul (number per 100 m nordic survey nets Cod Flounder ,5 4 3, cod Reef Nienhagen cod Reference Börgerende 3 2,5 2 1,5 1 0,5 0 flounder Reef Nienhagen flounder Reference Börgerende

13 Inde value (number per 100 m nets) Inde value Reef Nienhagen Mean catch per haul (number per 100 m gill nets and nordic survey nets cobined) Cod Flounder cod Reef Nienhagen cod Reference Börgerende 5 4,5 4 3,5 3 2,5 2 1,5 1 0,5 0 flounder Reef Nienhagen flounder Reference Börgerende

14 Remarks This surveys use different gears and seasons (once a month in the reef area and only hours lasting hauls within the eel monitoring programme, The indices might benot comparable to the methods (gears) used in the Fish-Pro programme, Our reef programme will continue at least until 2015, The eel monitoring surveys probably until 2020, The responsible authorities in the state of Mecklenburg-Vorpommern seems to have no financial resources to announce a coastal fish monitoring project, It might be helpful to have some support from the HELCOM WG.

Key message. HELCOM core indicator report Abundance of coastal fish key functional groups

Key message. HELCOM core indicator report Abundance of coastal fish key functional groups Key message The status of functional groups of coastal fish in the Baltic Sea during the years 29-213 has been evaluated by assessing the status of piscivores (i.e. fish that feed on other fish) and cyprinids