A new selective fishing device facilitates Norway lobster capture with minimum impact for the cod. (Photo: Stock File)

New lobster trawl reduces cod by-catch by 90 pc

Researchers from the National Institute of Aquatic Resources (DTU Aqua) have developed a selective trawl for the Norway lobster fishery in the Kattegat that lets up to 90 per cent of cod escape.

This “SELTRA-trawl” started being used on 15 July and has ensured that fewer cod end up as by-catch in the lobster trawl. The Danish Ministry of Food, Agriculture and Fisheries has made the new trawl use obligatory for all Norway lobster fishing in the Kattegat.

Senior research scientist Niels Madsen DTU Aqua, who has been in charge of developing and testing the SELTRA-trawl, noted that the lobster fishery is the most lucrative in the Kattegat and is in good shape, with 1,700 tonnes caught in 2010. Conversely, cod stocks have plummeted in the last 20-30 years.
 
”If it had not been possible to reduce the by-catch of cod by implementing the SELTRA-trawl, the Norway lobster fishery would have to be reduced significantly in order to protect the cod,” he said.
 
A trawl catches Norway lobsters and bottom-dwelling fish when it is pulled along the bottom of the sea. The catch falls towards the end of the trawl and into the codend.
 
The researchers wanted to design a trawl that selectively catches Norway lobsters while letting cod and other larger by-catch escape. The researchers decided to replace the traditional round codend with one shaped like a square box.

The seven metre long SELTRA-trawl has been designed to replace the rearmost end of the fishermen’s own trawl  (Illustration: Niels Madsen, DTU Aqua)

 
They then saw that the lobsters preferred the bottom part while the cod preferred the upper part and tried to swim against the current to get out. The researchers then created a sorting box with a larger mesh size and placed it in the front end of the SELTRA-trawl, which allows cod to escape.

To keep costs relatively low, the SELTRA-trawl was designed to be added to the fishers’ own trawl so they do not have to buy a new one.
 
”The fishermen fishing for Norway lobsters has their own trawl already, and all they need to do is to place the seven metre long SELTRA-trawl with the sorting box and the square codend instead of the rearmost part of their own trawl,” Madsen explained.
 
The SELTRA-trawl has been used on commercial fishing vessels in the closed areas in the Kattegat, where the Ministry has banned cod fishing to protect their reproduction.
 
”In some places in the closed areas, the fishermen have been required to use the SELTRA-trawl when fishing for Norway lobsters. The fishermen, who have now used the SELTRA-trawl for a couple of years, say that they have not experienced significant reductions in the amount of Norway lobsters that they catch,” Madsen noted.

Related article:

- Danish Govt, EU and Norway try to curb discards  

By Natalia Real
[email protected]
www.seafood.media

Address:	Jægersborg Allé 1
City:	Charlottenlund
State/ZIP:	(DK-2920)
Country:	Denmark
Phone:	+45 35 88 33 00
Fax:	+45 35 88 33 33
E-Mail:	[email protected]
More about:

Print