One of the Norwegian pelagic fishing fleet goals is to increase the share of its catch processed for human consumption. This change is important for the value adding of the pelagic fisheries. A challenge for the fleet has been to develop new better systems for catch handling and storage on board making them able to deliver high quality raw material for further production to food. Pelagic purse seine catches are traditionally loaded by vane pumps and unloaded by vacuum pumps. The pumping systems and valves are known to cause damages to the fish such as bruises/bloodspots and cuts. The damages may lead to downgrading of overall catch quality and price, as well as various shares of low price co-streams no longer suitable for human consumption. Alternative technologies are wanted in order to reduce these damages. We present such an alternative in the form of a new concept for loading, storage and unloading of pelagic fish based on controlled under- and over-pressure in flow lines and tanks. The concept has been fully prototyped and is installed on board a Norwegian purse seiner.
During the research&innovation of the concept, several research cruises have been conducted, testing prototypes and comparing them with traditional catch handling systems. Tests on effectiveness, functionality and effects on the quality of Norwegian spring spawning herring (Clupea harengus L.) and mackerel (Scomber scombrus) have been performed. The most common types of fish damages, and their causes, have been identified. Types of damages leading to downgrading to a raw material no longer suitable for human consumption have been quantified. An objective machine vision method for quality measurements has been developed.
The new concept for gentle and effective catch handling and storage of pelagic fish onboard will be described and a summary of the comparison with traditional systems will be presented.