Rebuilding Plan for demersal stocks in the North Sea -� need for effective juvenile protection through an enhanced technical regulations and spatial management.

Posted by Ian on November 17, 2011 under Uncategorized | Be the First to Comment

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The EU’s plan for re building demersal fish stocks in the North Sea has been strongly influenced by castle in the sky thinking and is shamefully ineffective. The plan has lacked potency, both practical and political. It helps little with fishing capacity/ effort and quota reductions, when these reductions do not affect the behaviours of fishermen to the positive for the fish stocks, some thing which in turn will again benefit the fishermen. Fishermen in the North Sea have been entrapped over a long period in a negative spiral of bone scraped fish quotas and the insane mandatory practice of returning under sized and non-target fish back to the sea, fish that in reality are either dead or dying. Minimum landing sizes need to be related towards the protection of fish under spawning age. The best protection for immature fish is by avoidance.
The fisheries in the European sector of the North Sea takes place mainly with bottom trawls. Trawl fisheries are mainly regulated by a “one net” system, where white fish trawls TR1 and nephrops trawls Tr2 are regulated separately, with respectively 120 and 80 mm mesh size. Despite different measures taken over the last years by both management and the fishing industry, the discard and the mortality rate is still too high.�
Much time and effort has been devoted to the cod recovery plan in the North Sea, under the “cod avoidance plan.”  The plan has been a mix of spatial management and voluntary attempts and use of various technical devices, including the Eliminator and Orkney trawls, as well as the use of diverse «squareless» nephrop trawls. ” Cod avoidance” by the use of technical devices has provided mixed results. The experiments with “eliminator trawl” has shown good results in certain fisheries, with between 80-90% reduction in cod catches without significant reduction in haddock and whiting catches.  Research has also shown that catches of other bottom fish and benthos were dramatically reduced. The loss of valuable demersal species such as lemon, megrims, plaice and monkfish etc, has made a large dent into the economy of these vessels.
The research trials with the “orkney trawl” has shown some positive results, with up to about 60% reductions of cod under the MLS 35cm being caught.  The effect of the “orkney trawl”diminishes with larger sizes of cod , with reductions being down to 7-8% for cod over 70 cm. The use of the Orkney trawl as with the eliminator trawl” has also resulted in reduced catches of valuable demersal species such as lemon, megrims, plaice and monkfish etc.
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Precautionary areas have been established in the Norwegian sector, for both the Patch Bank and Viking Bank. Fisheries in these areas are very important for many fishermen from Scotland and Denmark. Large quantities of juvenile fish can pose a problem at times in respect to keeping
catches within the legal allowance for fish under MLS . (Measured in number in the Norwegian sector – not by weight)
Area closures are common, especially in the spring and early summer. Catches of undersized fish have been as high as 40%, despite the use of various voluntary measures to improve selectivity.

Selection capabilities of a cod end and extension piece with diamond mesh in the normal position, has the greatest effect at the catch zone where the meshes are splayed out by fish retained in the cod end.  Water speeds may be more favorable in this area, aiding the fish to escape the open meshes.  Selection capabilities decrease reasonably fast towards the middle of the extension – the mesh opening can be as low as 20-30%. Mesh size provisions for Tr 1 120mm refer only to the minimum mesh size, maximum number of meshes round the cod end and the total length of the cod end / extension piece. Present gear regulations do little to set specific requirements to functionality regarding the selection capabilities of cod end / extension piece combinations.�
The use of 4 paneled  extension piece/ cod end, with the combination of T90 and square mesh over panel, will give more form stability and increase the selection capabilities significantly.�
Selection should be made as far forward in the trawl as possible to reduce the hard physical stresses young fish may be exposed to on the way down to the cod end. . Species selection can be further enhanced by the use of trawls designed to make use of behavioral patterns specific to target species.�
Use of the eliminator and orkneytrawl has provided both fishermen and scientists with invaluable information of the relationship between mesh size in trawl mouth and the fish’s behavior pattern – this is an important tool in the making of trawls that are more target species selective.  Research done by Seafish with a trawl divided by 2 vertical panels, and having 3 separate cod ends , has provided useful information on the behavior of different species in the mouth of the trawl. The sum of these research projects, and the knowledge gained, provides a good basis for constructing�
a trawl type that is most suitable for white fish fisheries in the northern part of the North Sea�
After having discussed the need for a new improved white fish trawl/ extension piece and cod end, with gear technologists from Sintef Fisheries and aquaculture, Seafish and others, – the conclusion was unanimous – the industry has an acute need, and the capabilities of designing a trawl/trawls that would better address both the requirements for selection and retention of target species.�
Selection in mixed demersal fisheries will be in varying degrees, subjected to “trade-offs.”  – the clue is to make the trade offs that benefit both man and fish.
The CPF reform takes aim at introducing a discard ban over a 3 years period from 2014. To reach this goal in an ethical and credible manner, a discard ban has to be founded on the effective selection and avoidance of juveniles and non target species.�
Time passes quickly, and the ever faster moving «sustainability train» has long since left the station, loaded with consensus from NGO,s for a discard ban, CCTV monitoring, catch credit systems and the like. The fishing industry needs to adopt a «back to scratch» approach to size and species selection – starting at the trawl doors, and down to the cod end. There has never been or will be a better time to make the necessary gear changes than now in relation to knowledge base, gear monitoring equipment, gear component etc. Much of trawl gear research start with model experiments in the flume tank in Hirtshals. The center is a hub for fishing gear research in and around the North Sea, and a natural choice as project manager / partner for joint projects. The industry has loads of «tools» at it,s disposition- it,s now as always a question of putting the right tools in the right«tool box»