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There is an urgent need to find alternative feed resources that can further substitute fishmeal in Atlantic salmon diets without compromising health and food quality, in particular during the finishing feeding period when the feed demand is highest and flesh quality effects are most significant. This study investigates efficacy of substituting a isoprotein (35 %) and isolipid (35 %) low fishmeal diet (FM, 15 %) with Antarctic krill meal (KM, 12 %) during 3 months with growing finishing 2·3 kg salmon (quadruplicate sea cages/diet). Final body weight (3·9 (se 0·04) kg) was similar in the dietary groups, but the KM group had more voluminous body shape, leaner hearts and improved fillet integrity, firmness and colour. Ectopic epithelial cells and focal Ca deposits in intestine were only detected in the FM group. Transcriptome profiling by microarray of livers showed dietary effects on several immune genes, and a panel of structural genes were up-regulated in the KM group, including cadherin and connexin. Up-regulation of genes encoding myosin heavy chain proteins was the main finding in skeletal muscle. Morphology examination by scanning electron microscopy and secondary structure by Fourier transform IR spectroscopy revealed more ordered and stable collagen architecture of the KM group. NEFA composition of skeletal muscle indicated altered metabolism of n-3, n-6 and SFA of the KM group. The results demonstrated that improved health and meat quality in Atlantic salmon fed krill meal were associated with up-regulation of immune genes, proteins defining muscle properties and genes involved in cell contacts and adhesion, altered fatty acid metabolism and fat deposition, and improved gut health and collagen structure., This work was funded by Aker Biomarine Antarctic AS, Oslo, Norway

This paper (1) reviews the history of sealing and whaling in the Southern Ocean to illustrate how market demands combined with no or ineffective regulation of catches led to the overexploitation and near extinction of southern fur seals, southern elephant seals and all but one of the Southern Ocean populations of large whales; (2) indicates how the overexploitation and depletion of krill-eating whales led to the Krill Surplus Hypothesis, and the development of the Antarctic krill fishery and the Convention on the Conservation of Antarctic Marine Living Resources (CCAMLR); (3) points out how misinterpretation of the reference to ‘rational use’ in CCAMLR Article II(2), combined with consensus decision-making and the potential growth of markets for Antarctic krill, could lead to ineffective regulation of the krill fishery and adverse effects on the krill resource, on recovery of depleted populations of krill-dependent whales, and on other ecologically related species and populations; and (4) identifies reasonable actions that could be taken cooperatively by the International Whaling Commission and the CCAMLR Commission to minimise the risk that the krill fishery will prevent or impede recovery of depleted populations of krill-dependent whales.

Antarctic krill has been studied for many decades, but we are still long way from understanding their biology to be able to make reliable predictions about the reaction of their populations to environmental change. This is partly due to certain difficulties in relation to logistics, operations and survey design associated with scientific surveys that have been obstacles for us to better understand krill biology. The krill fishery is the largest fishery in the Southern Ocean, continuously operating since early 1970s. Recent studies revealed its potential to be used as a unique source for scientific discussions to understand krill biology. In this paper, after a brief overview of krill fishery operation and krill biology, we examine how current data collection through the fishery operation could contribute to a greater understanding of krill biology, and then suggest future priorities for fisheries-related research in relation to recent changes in the Southern Ocean environment.