Spawning


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Spawning

 

the depositing by fish of their reproductive products—mature roe and milt (seminal fluid, ejaculate)—with subsequent fertilization. In most fish, fertilization of the roe is external, occurring outside the body of the female, in water. Fertilization occurs in certain definite places, or spawning grounds, where conditions for development of offspring are favorable. Lithophilous fishes, such as sturgeons and salmon, deposit their roe on rocks. Phytophilous fishes spawn on vegetation and include the carp and the European bream. The roe of pelagophilous fishes, such as the tolstolobik (Hypophthal-michthys molitrix) and the chekhon’ (Pelecus cultratus), undergo development in open water.

Every species of fish is adapted to particular spawning conditions—to a certain water temperature and salinity and to a specific substrate. Many fishes take on a special mating dress. The presence of certain conditions and of individuals of the other sex signal the start of reproduction. In the USSR much work is being done in the study of spawning conditions and in the protection of the spawning grounds of commercial fishes.

REFERENCES

Nikol’skii, G.V. Ekologiia ryb, 3rd ed. Moscow, 1974.

G. V. NIKOL’SKII

References in periodicals archive ?
Fisheries officer Paul Frear said: "There are now more than 20 spawning areas in the burn compared to the handful we've seen in previous years.
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The spawning reef, comprised of the rock donated by Vulcan Materials Co.
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Catch and effort in the southern California recreational fishery is highest during peak spawning season (June to August) when barred sand bass form large spawning aggregations over sort bottom habitat in depths of 20 to 40 m (Turner et al.
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However the species is subject to many pressures in Europe, including pollution, the introduction of non-native salmon stocks, physical barriers to migration, exploitation from netting and angling, physical degradation of spawning and nursery habitat, and increased marine mortality.
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MOST of the major Scottish salmon rivers are now closed to give salmon peace and quiet to get on with the business of spawning.