Acronym NA
Category
Fisheries
Title Åtefri brisling: Utvikling av ny trengingsmerd fase II - Eating-free sprat: Development of a new penetration cage phase II Programme National Programme
Instrument (FP6)
Contact Type (FP7)
Strand (Interreg)
NA
Theme (FP7)
Activity Area (FP6)
Regional Area (Interreg)
Action (COST)
NA
Specific Programme (FP7)
NA
Funding source National
Coordinator institution
IMR - Institute of Marine Research (Norway)
Institutions involved
NA
Start year 2008 End year 2008 Funding (€) € NA Website https://www.fhf.no/prosjekter/prosjektbasen/900013/ Summary "Locking is common in pelagic coastal fishing, where the catch is either to be kept for later trading, or to be the subject of crowding to make the fish food-free. In Western Norway, fishing for sprat and mackerel is an important fishery, but the quantity of sprat has decreased in recent years, from approx. 12,400 tonnes in 2001 to approx. 1,500 tonnes in 2004. This is due to both lower participation and weak year classes.
Sprat fishing is often carried out by old vessels, without larger tank capacity and RSW. The fish are locked in places where local fishermen know that it is possible to make sprat, herring or mackerel food-free. These anchorages have water qualities that mean there is little food in the area. As the fish does not get access to new food, it becomes food-free after a few days. When the fish are concentrated, or crowded, a certain mortality occurs in this phase. In order to reduce the proportion of fish that die, there is a strong desire for equipment and methods that can improve survival and facilitate the entire threshing operation.
Based on the fishermen's experiences with locking and the need for, for example, sprats, it could seem that the area of the cage is important for maintaining the shoal structure. In 2005, these experiences were linked to the development of a prototype of a flat-bottomed cage for the acclimatization of wild-caught cod, and this generated an idea to use the same flat-bottomed concept for the breeding of sprats. In contrast to traditional cages, a flat-bottomed cage could be lifted up and provide less volume for the fish (crowding), while the flat and rigid bottom surface would ensure that the area of the cage was maintained. When the area remained constant, the shoal structure would most likely be maintained longer than in a traditional cage, and it was assumed that this could improve the welfare of the sprat during the crowding phase, which in turn could increase the survival of the fish in this phase of capture processing.
With this as a background, the project was planned to be carried out in two phases, of which Phase I was to concentrate on further development of the flat-bottom concept and then in parallel with the development of acclimatization cages for cod in catch-based aquaculture (Isaksen 2010). Phase II was to concentrate on practical experiments with the penetration of sprats in commercial fishing, with a comparison of new and traditional penetration nets with regard to handling characteristics, as well as sprat survival.
Achieved results
The trestle cage that was developed and tested in the trials has acceptable handling characteristics, and with a little training in use, could be deployed from a vessel and be operational within an hour. The trenging cage is, however, too small for use in sprat fishing, where there are often 15 to 20 tonnes of sprat in one and the same cage. According to experienced fishermen, the new cage will be able to accommodate a maximum of five to six tonnes of sprat.
The narrowing net will be able to be scaled up, but it will most likely be difficult to handle for vessels under 50 feet.
"
Keywords
Sprat;
Fish;
Fishing vessels;
Mackerel;
Fishing technology;
Storage;
Gear technology;
Marine Region
13
Northern North Sea (27.IVa)
1
Marine Region Map
