Stock fish

Lakes that have been acidified cannot support the same variety of life as healthy lakes. As a lake becomes more acidic, crayfish and clam populations are the first to disappear, then various types of fish. Many types of plankton—minute organisms that form the basis of the lake s food chain—are also affected. As fish stocks dwindle, so do populations of loons and other water birds that feed on them. The lakes, however, do not become totally dead. Some life forms actually benefit from the increased acidity. Lake-bottom plants and mosses, for instance, thrive in acid lakes. So do blackfly larvae. 

Marshall. C.T. Yaragina, N.A. Lambert, Y. Kjesbu, O.S. (1999) Total lipid energy as a proxy for total egg production by fish stocks. Nature, 402, 288-90. 

It is not difficult to assess the average biomass of a fish stock over many years, using data on the numbers and biomass of samples. In Black Sea anchovy, it is 284 kt in May. By November the figure doubles as a result of replenishment and of somatic increase. The average annual biomass (B) amounts to 426 kt for anchovy, 280 kt for sprat, about 36 kt for horse-mackerel, 6 kt for red mullet and 9 kt for whiting (no data are available for pickerel). Results of the studies on annual specific and absolute production in populations of the fish examined here and Px/B coefficients are given in Table 11. 

Shatunovsky (1980) suggested a system of biochemical approaches for taking the maximum number of fish from commercial stocks in northern seas without exhausting the populations. He consulted data about somatic and generative increase in a number of age groups, the sex ratio and the natural death rate. A mathematical model of fish stock exploitation was created by... 

Badenko, L.V., Dorosheva, N.G., Kornienko, G.G. and Chikhacheva, V.P. (1984). The ecologo-physiological base for increasing the efficiency of commercial rearing of Azov sturgeons (In Russian). In Replenishment of Fish Stocks in the Caspian and Other Seas (I.B. Bukhanovich, ed.), pp.88-101, Moscow. 

Berdichevsky, L.S. (1964). The Biological Basis of Efficient use of Fish Stocks (In Russian), Nauka, Moscow, 36 pp. 

Chikhachev, A.S. (1984) Genetic control over the population structure and hybridization of valuable fish stocks in artificial breeding (In Russian). In Genetics, Selection, Hybridization of Fish (V.S. Kirpichnikov, ed.), pp. 16-20. Rostov-on-Don. 

Gerbilsky, N.L. (1941). The method of hypophysial injections and its significance for fish culture (In Russian). In The Method of Hypophysial Injections and its Significance for Reproduction of Fish Stocks (N.L. Gerbilsky, ed.), pp.5-36. Leningrad University Press, Leningrad. 

Jamieson, A. (1974). Genetic tags for marine fish stocks. In Sea Fisheries Research (F.R. Harden Jones, ed.), pp.91-99. Elek Science, London. 

Malikova, E.M. (1967). Some aspects of reproduction related to improving fish stocks in Latvia (In Russian). Vopmsy Ikhtiologii 7,961-966. 

Taranenko, N.F. (1964). Fat content of Azov anchovy as an index of reproductive capacity of the fish stock and the migration term (In Russian). Trudy Azovsko-cher-nomorskogo Nauchno-issledovatelnogo Instituta morskogo Rybno Khozyaistva i Oceanografii 22,137-147. 

Littler, M. M. and Littler, D. S., Disease-induced mass mortality of crustose coralline algae on coral reefs provides rationale for the conservation of herbivorous fish stocks, Proc. 8th Int. Coral Reef Sym., 1, 719, 1997. 

The interest to the Sea of Azov was always related to its large fish stocks, which are inferior only to that of the Caspian Sea. Annual fish hauls (sturgeons, pike-perchs, breams, and sea roaches) in this small sea reached 300 kt. This triumph of fishery was confined to the period of the natural harmony between the processes in the sea, when it was characterized by a high quality of the environment. 

After the Caspian Sea, the Sea of Azov is the second most significant inland basin of the former USSR with respect to its fish stocks. Recently, every hectare of its area provided 80 kg of fish, half of which was represented by valuable and very valuable species (sturgeons, pike-perches, breams, sea roaches, and others). The annual fish production in this smallest sea reached 300 kt. This triumph of the Sea of Azov fishery was related to the times of complete harmony between the natural processes, when the sea was characterized by a high quality dwelling environment. 

The high provision of the reproduction of fish stocks for migratory and semi migratory species alone, the total spawning area exceeded 600 000 hectares, while the habitat of marine fish covered the entire sea area. 

In August 1988, a new Black Sea invader - the ctenophore Mnemiopsis leidyi - appeared in the Sea of Azov it was first encountered near the Kerch Strait in the southern and eastern parts of the sea. From that time, every spring or summer, Mnemiopsis leidyi has penetrated into the Sea of Azov from the Black Sea with currents to provide an outburst in its development in the summer or early autumn. Then, it became extinct at the temperature drop below 4 °C at the end of October to November [28]. Mnemiopsis leidyi negatively affected the ecosystem of the Sea of Azov and undermined its fish stocks. 

Studenikina El, Volovik SP, Tolokonnikova I, Frolenko LN, Selivanova EV (1998) Current characteristics of benthic communities in the Sea of Azov. In Makarov EV, Volovik SP, Tyutina YuE (eds) The main problems of the fishery and preservation of fish stocks of the Azov-Black Sea basin. AzNIIRKH, Rostov-on-Don, p 67 (in Russian)... 

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