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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Farmed fish with a long history and an uncertain future


EM6 17 common carpThe common carp (Cyprinus carpio) is not only one of the best-known but also one of the most frequently produced freshwater food fishes. Nearly 4.2 million tonnes of this species were reared in carp ponds or in polyculture in 2014, plus a further 150,000 tonnes from fishing. Carp were already popular as food fish in the ancient world, and in Central Europe centuries-old carp fishing ponds are today part of the cultural landscape.

The original distribution area of common carp is in the warm temperate regions of South East Europe and Asia from the Black Sea, through Asia Minor and China, to Japan. The Romans introduced the species to Central Europe about 2,000 years ago and today it is to be found all over Europe, with the exception of Scandinavia. Within this extensive area, however, the species structure is widely controversial. Some taxonomists distinguish four subspecies whose core centres are thought to be found from the Danube River basin to the Ural Mountain range, in the Aral Sea, in the Amur River basin to southern China, and in the waters of North Vietnam. Other experts differentiate only two subspecies – C. c. carpio and C. c. haematopterus, while a third group sees rather a uniform species status. Morphological methods alone hardly enable any satisfactory distinction for, with regard to its body shape, the common carp is one of the most variable freshwater fish species.

Almost 97 per cent of global carp production today comes from farms. Genuine wild stocks are only to be found in a few waters, and the original wild carp is considered threatened. The carp that swim in natural waters are mostly farmed forms which have been released intentionally or have escaped from aquaculture facilities. Since carp can live for more than 50 years they can be found today in numerous waters. Carp particularly like slow-flowing or standing waters, such as the middle and lower reaches of rivers, but also ponds and lakes. There the fish like to keep to shallow vegetated coves, or shallows near the riverbanks. Although carp can survive cold winters they hardly eat or grow during such periods. They like warmer waters and the optimum water temperature for growth is above 20° C. This makes it clear why despite many centuries of selective breeding that has produced at least 30 to 35 breeds throughout Europe, the species can only exploit its full growth potential in the southern regions of the continent. Apart from temperature, however, the requirements for the water parameters are not high. Carp tolerate salinities of up to five per thousand, pH values between 6.5 and 9, and can survive low oxygen concentrations of 0.3 to 0.5 mg/litre.

Carp are often said to be herbivores, but in fact they are omnivores, for they make use of a wide range of food of both vegetable and animal origin. They eat insect larvae, worms, mollusks, and also occasionally young fishes, aquatic plants and other organic material, which is crushed with the fish’s strong pharyngeal teeth which are located on the rear gill arches. For this purpose, the pharyngeal teeth rub against the lenticular, curved, hard lapis carpionis, a plate between the indentation of the occipital bone and the first vertebra. Carp finds its food preferably in the bottom water layers or in the muddy bed of ponds and rivers. They usually begin to search for food at dawn, using their two pairs of barbels on the upper lip for detection and then sucking the food in with the trunk-like protuberant (protractile) mouth. With good nutrition and optimum temperatures carp can grow by 2 to 4% of their body weight daily. In tropical and subtropical areas growth of 0.6 to 1.0 kg per year is possible. In the temperate regions of Europe, on the other hand, carp need two to four growth periods (summers) to reach weights of between 1 and 2 kg.

Published in Frontpage rotator
Wednesday, 13 December 2017 13:07

Europe's carp farming needs new marketing ideas

Farmed fish with a long history and an uncertain future

EM6 17 common carpThe common carp (Cyprinus carpio) is not only one of the best-known but also one of the most frequently produced freshwater food fishes. Nearly 4.2 million tonnes of this species were reared in carp ponds or in polyculture in 2014, plus a further 150,000 tonnes from fishing. Carp were already popular as food fish in the ancient world, and in Central Europe centuries-old carp fishing ponds are today part of the cultural landscape.

The original distribution area of common carp is in the warm temperate regions of South East Europe and Asia from the Black Sea, through Asia Minor and China, to Japan. The Romans introduced the species to Central Europe about 2,000 years ago and today it is to be found all over Europe, with the exception of Scandinavia. Within this extensive area, however, the species structure is widely controversial. Some taxonomists distinguish four subspecies whose core centres are thought to be found from the Danube River basin to the Ural Mountain range, in the Aral Sea, in the Amur River basin to southern China, and in the waters of North Vietnam. Other experts differentiate only two subspecies – C. c. carpio and C. c. haematopterus, while a third group sees rather a uniform species status. Morphological methods alone hardly enable any satisfactory distinction for, with regard to its body shape, the common carp is one of the most variable freshwater fish species.

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HalbutWhen people talk about halibut in Europe they usually mean Reinhardtius hippoglossoides: Greenland halibut or black halibut. The name halibut is derived from haly (holy) and butt (flat fish) due to its popularity on Catholic holy days.

The species’ geographic range extends along the Norwegian coast as far as the cold North Atlantic waters off Greenland, Iceland and Spitzbergen. It is thus to be found in the same habitat as the Atlantic halibut Hippoglossus hippoglossus, a relatively close relation that is considered to be the “real” halibut in a lot of other countries. Although the two species are similar in appearance and behaviour closer examination reveals a number of noteworthy differences.

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Northern shrimp or Coldwater shrimp (Pandalus borealis) which is found all around the Arctic is the most frequent and economically important species of the decapod genus Pandalus. The firm, tender flesh of this coldwater shrimp is deemed particularly tasty. Despite its relatively small size it has been targeted by the fishing industry since the early 20th century. However, the stocks have been declining for several years, probably as a result of global climate change.

Published in Species
Thursday, 01 September 2016 00:00

Climate change drawing squid northwards

Squid in handThe common squid (Loligo vulgaris) and other cephalopod species are of economic significance, especially in southern Europe. Landings from the fishing sector are decreasing, however. For one thing, because the size of the squid populations is strongly influenced by environmental factors, and for another probably because squid are too intensively fished. There is no effective fisheries management, although this would be urgently needed.

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