EM4 19 News warm oceans biomass lostThe world’s oceans will likely lose one-sixth of their fish and other marine life by the end of the century if climate change continues its current trajectory, a new study finds. Every degree Celsius that the world’s oceans warm, the total mass of sea animals is projected to drop by 5% according to a comprehensive computer-based study by an international team of marine biologists at the American National Academy of Sciences. The Intergovernmental Panel on Climate Changes special report on global warming already estimates that as of 2017, human activities were responsible for global mean temperature rise of one degree Celsius above preindustrial levels. Unless reductions are made by the world’s leading carbon emitters the world will likely warm by two degrees Celsius above preindustrial levels by 2100.

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EM5 17 SP AlaskaPollackTheir fillets are used for fish burgers, fish fingers, as well as different surimi products.  Alaska pollock can be utilized for different purposes and at relatively affordable cost. Their stocks constitute the largest and the most economically important ground fish resources in the North Pacific Ocean. They are both, well managed and fished on sustainable basis. Yet depletion of their stocks occurs primarily due to natural causes. On that score, a dramatic role is played by the climate change.

Although the walleye pollock (Theragra chalcogramma) known also as the Alaska pollock is a close relative of Atlantic cod, saithe and haddock, intensive fishing started only 50 years ago.  Before that, interest in this species was surprisingly low which could possibly be explained by its relatively small body Despite a record length of 91 cm, the length of individuals caught in the net seldom exceeds 50 cm while the weight barely reaches 500 to 600 g. The brownish or greenish coloured, beautifully spotted fish live in large schools at a depth of between 30 and 500 m. In terms of biomass, the stocks of Alaska pollock belong to the largest and most important stocks of food fish due to three main reasons. First, they grow relatively quickly reaching 30 to 40 cm length already at the age of three or four years. From this point onwards, they can spawn virtually every year thus contributing to the survival of the species. It is universally assumed that Alaska pollock lives a maximum 14 to 15 years. Second, their fertility rate is really high. The exact number of eggs depends upon a number of factors including the age, the size and the nutritional status of females, however on average it ranges from 100,000 to 1.2 million. The third reason for the high importance of Alaska pollock is the wide spectrum of feed they use. Although carnivorous they can consume plankton-eating krill or young herrings available in copious amounts in the North Pacific.  In the Bering Sea, Alaska pollock accounts for almost 60% of the total fish biomass, while in the Gulf of Alaska and Aleutian Islands they constitute about one fifth of the total fish biomass.

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