Nofima reports

Rapport/Report 39/2014 English summary

Olsen, Stein Harris; Digre, Hanne; Grimsmo, Leif; Toldnes, Bendik; Eilertsen, Aleksander; Evensen, Tor Hatten; Midling, Kjell Øyvind

Publication details

Publisher: Nofima AS

Issue: 39/2014

Number of pages: 55

International Standard Numbers:
Printed: 978-82-8296-228-5

Open Access: green


Generally, fish caught by trawl is reputed to have a poorer quality than fish caught by long-line. In the last 30 years the technological progress in processing of whitefish on board trawlers has been very low. This contributes to the whitefish industry being way behind the salmon industry in innovation and technological development, both with regard to handling/slaughtering and fileting. The industry has carried out a considerable structuring to improve profitability. Today, trawling shows signs of very strict demands of effectiveness with lots of demanding physical tasks. With regard to target areas in the technological development of the trawling fleet, the focus has been on reducing fuel by means of vessel design, developing different tools as well as making the output more efficient (by the use of already known technology). However, not much effort is invested into the handling of the catch. Therefore, the strategic initiative is to put emphasis on a common goal of improving the quality of fish, in order to establish and increase the value of trawl captured fish.
This project is in the first phase of a larger project plan, which consists of three different phases. In phase one; the objective is to carry out a feasibility study and complete selected experiments to enable the correct implementation of the right technology for the most effective on board production of whitefish.
The overall goal for this project is to contribute to, and develop, the competitive power of the trawling fleet by moving the quality of the product of the fleet towards optimal quality (as good as “practicable”).
The focus is on the processing, from the fish is in the codend and until the processed and finished raw material is packed and put in storage. To ensure an effective and stabile quality in the handling, as well as a viable production on board, this project has identified possible technology/equipment that can be used – as well as which ones need to be developed for the future processing on board trawlers.
Experiments on J. Bergvoll in May 2014 show that pumping is considerably gentler than pulling up the slipway and survival rates of 80–100% can be achieved. The knowledge gained during the excursions form the basis for the future design of trawlers. There are also conducted experiments with mechanical stunning and bleeding (Baader SI-7). At harvest trials conducted in February 2014, 93.4% of the test fish showed no movement after stunning and 97,3% were bleeding (blood loss of 1.6 ± 0.2 % of body weight). Thus, the machine gave equally white fillets compared to correct manual bleeding. There are also conducted experiments with electrical stunning (STANSAAS # 1) and bleeding machine (prototype 2). Prototype 2 obtained in the field test 62% correct bleeding, but are still under development. Electrical Stunning works well for haddock and cod, but some challenges are observed for saithe regarding broken vertebrae and bruises.
This project represents a will to switch to automation and improve the fish quality within the Norwegian fishing industry. Thus, this project will contribute to the establishment of live storage- and automatization systems in the processing line on board the trawling fleet. This is a necessary step to gain an economic, safe, first-class stable quality and efficient fish processing.