What differences are there in the catch composition of the shrimp pulse trawl compared to conventional fishery with the shrimp beam trawl? How can the selectivity of the shrimp pulse trawl be further improved?
Shrimp fishery with the pulse trawl
In the brown shrimp fishery with the pulse trawl, weak electric pulses are used to provoke a flight response in shrimp on the seabed so they swim into the net. There are indications that this method of fishing leads to less unwanted bycatch of fish below the minimum conservation size, small shrimp and other marine organisms living on the seabed (benthos). Electric pulse fishing is not allowed under European regulations, but a small group of brown shrimp fishermen has been granted an exemption to experiment with the fishing gear. The shrimp fishery with the pulse gear is not allowed in the Dutch Natura 2000 areas. These areas are, however, important fishing grounds for shrimp fishermen.
What are the research questions?
The study will need to answer the following questions: (1) Do the two types of gear differ from each other in the quantities of catches of marketable brown shrimp?; (2) Do the two types of fishing gear differ from each other in quantities of bycatches of undersized shrimp, fish and benthos?; (3) Are any such differences related to the fishing location and time of year?; (4) How can the selectivity of the shrimp pulse trawl be further developed and improved?
How will the results be used?
The results of the study are important for the management of shrimp fisheries. Among other things, an assessment is needed as to whether to allow shrimp pulse fishing in the Natura 2000 areas, and the results are also important for underpinning a general authorisation of the use of the shrimp pulse trawl.
How will the study be conducted?
The study will be conducted by a group of five fishermen who will fish with the shrimp pulse trawl and five conventional fishermen. The study will use data collected during the shrimp fishery. Both the shrimp pulse fishermen and the conventional shrimp fishermen will measure and record their total catch quantity and catch of marketable shrimp for each haul for a period of up to 12 consecutive months. In addition, the shrimp pulse fishers will also participate in a port/starboard comparison for three consecutive weeks each quarter. This means that they will simultaneously fish with a pulse trawl and a traditional shrimp beam trawl. During the comparative fishing the pulse fishermen collect samples that they submit at the fish auction when they return. Their samples are collected for analysis. During the third week two researchers will be on board to conduct the comparison. The shrimp fishermen who fish with the pulse trawl have been granted a special exemption to fish in the Natura 2000 areas based on a research fishing plan.