Size selection of herring (Clupea harengus membras) in a pontoon trap equipped with a rigid grid

Survival of juvenile herring (Clupea harengas membras) after passing through a selection grid in a pontoon trap

“…These numbers corresponds to 5.4 fish/m 3 or 68.2 fish/m 3 . In Lundin et al (2011a) it was demonstrated that the number of escapees augmented drastically after about 1 tonne. This corresponds to a density of 943.4 fish/m 3 .…”

“…All herring in the experiment were caught in a herring trap of the same type as used by Lundin et al (2011a). A single-walled pontoon fish chamber was attached to the trap and used as a fish-holding cage (Fig.…”

“…By equipping the pontoon trap with rigid grids, an effective exclusion of small herring from the catch can be achieved (Lundin et al, 2011a). But in order to ensure a sustainable fishery, the question must still be resolved as to whether allowing the escape of undersized herring in this way is enough.…”

The efficiency of selection grids in perch pontoon traps

“…In line with this, a new pontoon trap was recently developed for the commercial small-scale perch fishery, with the aim to be catch-effective while at the same time protect the caught fish from seal predation (Harmångers Maskin & Marin AB in collaboration with Programme Seals & Fisheries). The function and properties of the pontoon trap for perch is similar to the pontoon traps developed for the salmonid fishery (Suuronen et al, 2006;Hemmingsson et al, 2008) and the herring fishery (Lundin et al, 2011a) but is approximately half the size of the aforementioned. One drawback is that traps sometimes get large bycatches of undersized fish and non-target species.…”

“…The use of selection panels have been tested and evaluated in other types of pontoon traps, with good results (Lundin et al, 2011a(Lundin et al, ,b, 2015. In these tests non-commercial fish have been able to escape from the trap.…”