About fish behaviour of some bottom species in front of a bottom trawl

Image. MFRI

New publications have just been launched in the paper PeerJ about fish behaviour in front of a bottom trawl about what area the fish escape under the trawl. In regular bottom trawls, so-called Rockhoppers are used, which are rubber wheels that do not roll. Fish can escape between or under the wheels, but many times the fish swim up and end up inside the trawl. This trial was designed collect bags attached to behind the rockhoppers and under the trawl in three different areas. That is at both wings and behind the centre of the trawl. Doing this made it possible to observe in what area the fish did escape under the trawl and if there could be measured variation between species or sizes. Cod and haddock showed a length-dependent difference, with smaller fish mostly going under the centre of the trawl. In comparison, larger fish did escape at the wing area. Greater variation was found in flatfish. Then it was observed that monkfish did escape nearly 80% of the time at the wing area. From this same collection of data, work is ongoing to publish another paper explaining the quantitative measurement of these species with some other added species and what the day and night variation looks like. The expedition leader in this trial on the research vessel Árni Friðriksson was Haraldur Arnar Einarsson.

https://doi.org/10.7717/peerj.14746