River lamprey (Lampetra fluviatilis)
Fish fauna studies reveal the large-scale distribution and prevalence of fish species in the North Sea and Baltic Sea.
- The studies underscore the importance of reef and sandbank habitats for fish fauna, among other things as retreats, spawning areas and nurseries. The results can also be merged with bird and mammal survey data to pinpoint specific sites as key feeding grounds for fish-eating birds and marine mammals.
- Only very little evidence has so far been found in the North Sea and Baltic Sea for the presence of fish species requiring protection under Annex II to the Habitats Directive. Special catching methods still need to be developed so that these species can be recorded.
The following Habitats Directive species are presented under Fish Species:
- Twait shad (Alosa fallax)
- Allis shad (Alosa alosa) (Twait shad and allis shad are also known as ‘May fish’)
- Houting (Coregonus oxyrinchus) (North Sea only)
- Sea lamprey (Petromyzon marinus)
- River lamprey (Lampetra fluviatilis)
- Sturgeon (Acipenser sturio)
Key research findings
- The German Bight has its own characteristic composition of fish fauna. Concentrations of specific fish fauna communities can be identified in waters near the coast and in the area of Dogger Bank.
- Characteristic distributions of fish species can likewise be observed in the Baltic Sea, corresponding to the salinity gradient from west to east. Some marine species such as dab and whiting reach the eastern limit of their range in the German Baltic Sea. On the other hand, freshwater species tolerant of brackish conditions are found with increasing frequency towards the east, such as in the Pomeranian Bay.
- Prevailing capture methods are not suitable for surveying the full species range, notably when it comes to anadromous migrants such as lampreys and small fish species protected under the Habitats Directive. Special capture devices are needed, especially in areas where the sea floor is strewn with boulders.
Common dragonet (Callionymus lyra)
Black goby (Gobius niger)
River lamprey (Lampetra fluviatilis), spawning
Fish species
Habitats Directive Annex II species of relevance in the German
EEZ
comprise anadromous migrants (ones that migrate up deltas and rivers to spawn) and, in the Baltic Sea, freshwater species tolerant of brackish conditions. Germany must take these species into account when designating protected areas.
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Houting (Coregonus oxyrinchus)
Research methods
Scientists put to sea on research ships several times a year in the North Sea and Baltic Sea to study the size and composition of fish fauna using a range of trawl methods. Fish are caught in various depth zones using different types of trawl nets such as otter trawls and beam trawls. The entire catch is sorted straight away on board and the individuals of each species identified, weighed, measured and counted. The results are stored in a database maintained by the Johann Heinrich von Thünen Institute (vTI), the German Federal Research Institute for Rural Areas, Forestry and Fisheries.
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Casting a trawl net.