The first set of UK sea trials to assess the potential benefits of using ‘turned mesh’ or ‘T90’ netting has just been completed by Seafish, with encouraging results.
The eight days of comparative sea trials off Shetland aimed to evaluate the performance of a trawl constructed entirely of T90 netting.
Previous international studies have identified the selectivity advantages of T90, with there being additional benefits in the form of reduced drag and improved catch quality.
The trials were conducted on the Lerwick vessel "Mizpah".
The meshes in a T90 trawl are turned through 90 degrees compared with a traditional net, resulting in the net meshes being kept much more open. This compares favourably with a conventional trawl where the direction of pull tends to close the diamond shape meshes, resulting in increased drag and reduced selectivity.
Icelandic skippers using T90 trawls regularly record improvements in quality and catch rates (particularly of larger fish), but of particular interest to Seafish were reports on the reduction in drag caused by the lower amount of netting material required in the construction.
Results from the trials are currently being assessed and an interim report will be produced shortly. However, the initial findings, although encouraging, have not produced the level of difference between the standard and T90 trawl as originally expected.
Reductions in the drag of the trawl of around 20% were detected but without any significant changes in fuel consumption.
The catch monitoring results suggested that the more open T90 mesh configuration allowed more small fish, particularly whiting, to escape.
There was some indication that the T90 was catching more of the larger sizes of cod, haddock and saithe, but this was not conclusive or as noticeable as in the Icelandic experience.
Project manager Ken Arkley, however, is keen to emphasise that these preliminary trials can only offer a short ‘snapshot’ of the performance of the T90 trawl.
He says: “Seafish is hoping for more opportunities to test the performance of the T90 trawl and add to the data already collected so as to establish more conclusive evidence of its potential.”
In the meantime, the fully rigged T90 trawl (including groundgear) is available for any interested skippers wishing to try the net (contact Ken Arkley on tel. +44 (0)1482 327837 or email k_arkley@seafish.co.uk for more information).
