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 ?
1982) have found similar finding about the timing of maturation and spawning for S.
Based on histological examination and microscopic observation, developmental stages were categorized as indeterminate, developing, ripe, or spawning (see Table 1).
Although on several occasions the presence of nonreproductive adult individuals has been noted during the spawning season of Argentine hake (Macchi et al.
Following the conclusion of filming on the seventh day, all spawning pads were carefully transferred (under water) into separately labeled containers filled with natural spring water to obtain a visual count of the number of deposited eggs.
The male fish had established long-standing dominance of this site during the spawning season by remaining at the location, performing courtship display when females were present, and chasing other fish from the area.
The oocyte development was analyzed in females which were developing (in the beginning of the spawning season), spawning capable and actively spawning (from the middle to the peak of spawning months), following the histological staging adapted by Brown-Peterson et al.
In this study, we tested the hypothesis that offspring quality declines with successive spawning, given the potentially antagonistic relationship between reproduction and somatic growth in a freshwater caridean shrimp with direct development.
The data set for the statistical analyses contained information on 451 females and estimated the spawning probability (presence or absence of spawning), multiple spawning (females with more than one spawning) and spawning frequency (number of spawning obtained per female during the evaluation period).
The objectives of this study were to evaluate: (1) the phenology of spawning of the six abundant catostomid species and (2) associations between their reproductive condition and exogenous environmental cues.
The Environment Agency has paid for members of Chester-le-Street Angling Club to remove a weir and make changes to underground culverts to help fish move along the watercourse, which is believed to have helped the number of spawning sites increase.
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The spawning reef, comprised of the rock donated by Vulcan Materials Co.