Baseline study Fish, fry and commercial fishery Nysted Offshore ...

Bio/consult as Page 15
Figure 3.2.1 Seaworthy high-speed rubber zodiacs (Humber Dive Pro 6) were used in the field
studies of both baseline studies because of their exceptional steadiness.
3.3. Applied gears
Only passive (stationary) fishing gear was used for sampling as recommended (SEAS
2000 and SEAS 2001). The catch efficiency of passive fishing gear such as gill and fyke
nets depends on fish behaviour such as migration. Migration can be seasonal (e.g. while
spawning) or daily (e.g. while foraging in shallower and deeper waters within the local
area). The catch depends on factors such as the mesh size, time of day, oceanographic
conditions and weather conditions.
Biological sampling gill nets
The biological survey gill net (Lundgren gill net) is 42 metres long and 1.5 metres high.
It can be placed in a pelagic or benthic position. Pelagic nets are positioned 0.5-1 m
under the surface to reduce the risk of rolling and tangling. The biological survey net is
divided into 14 sections with different mesh sizes ranging from 6.25 mm to 60 mm (half
meshes).
Turbot net
The benthic biological survey nets used in this study was equipped with two additional
4 m long sections with mesh sizes of 90 and 110 mm, respectively, suitable for catching
larger flatfish like turbot.
Standard fyke net
The standard fyke net is a double-threaded cast net with a trap opening of 60 cm in
diameter. In each fyke net, there are three funnels with a mesh size of 17 mm in the
outer funnel, 14 mm in the middle funnel, and 11 mm in the innermost funnel. The
leader between the two traps is eight metres long and has a mesh size of 18 mm. The
leader has extra ballast to reduce rolling in bad weather.
SEAS. Baseline study – Fish, fry and commercial fishery Dok. nr. 2148-03-001-rev3 2P.doc