Krill Fishery - Technology

Technology

Krill are small animals, considered a type of zooplankton, and hence need to be fished with very fine-meshed plankton nets. Such nets pose several problems: they tend to clog fast, and they have a very high drag, producing a bow wave that deflects the krill to the sides. Trawling must hence be done at low speeds. Additionally, fine nets are also very delicate, and the first krill nets designed exploded while fishing through the krill schools. Furthermore, fine nets increase unwanted bycatch, such as fish fingerlings, which might have unforeseen side-effects on the ecosystem, even though large krill aggregations tend to be monospecific.

Yet another problem is bringing the krill catch on board. When the full net is hauled out of the water, the organisms compress each other, resulting in great loss of the krill's liquids. Experiments have been carried out to pump Antarctic krill, while still in water, from the cod end of the net through a large tube on board. This method had already been used by the small fishing boats in Japanese waters; it increases the capture capacity and the processing rate of krill.

One of the first Antarctic krill trawlers to use this technique was the FV Atlantic Navigator, registered in Vanuatu and owned by the Norwegian-based company Aker ASA, which used this technique in the 2003/04 and 2004/05 fishing seasons. In these seasons, this ship alone caught 25% and 38% of the whole krill catch in CCAMLR regions. The successor ship of the Atlantic Navigator, the FV Saga Sea, can fish up to about 120,000 tonnes of krill annually, and Aker announced plans to build more such ships.

Krill must be processed within one to three hours after capture due to the rapid enzymatic breakdown and the tainting of the meat by the intestines. They must be peeled because their exoskeleton contains fluorides, which are toxic in high concentrations.