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 ?
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).
"While reproductive success during split spawning may be lower than usual because it can lead to reduced fertilisation, we found that the release of eggs in two separate smaller events gives the corals a second and improved chance of finding a new home reef."
Large variance in GI in a given month was taken as evidence of spawning season because it suggests that both gravid (high GI) and recently spawned (low GI) individuals were present at that time point.
Specifically, we evaluated differences in spawning seasonality, batch fecundity, and spawning interval across time.
In the western Caribbean, fishers from Mexico, Belize, Guatemala and Honduras traditionally harvest spawning aggregations of groupers (Epinephelidae) and snappers (Lutjanidae) over high relief areas of the fore reef (Craig, 1966; Castro-Perez et al., 2011; Heyman & Granados-Dieseldorff, 2012).
Studies using visual observation of reproductive interactions can be limited because (a) instream conditions do not always allow for visual observation, (b) reproductive interactions vary spatially with changing instream conditions determining interaction outcomes (Peoples and Frimpong, 2016), and (c) interactions vary temporally, with different associate species participating (and perhaps performing different functions) throughout the spawning season or at night when observations are difficult to make (Maurakis and Woolcott, 1996).
Female spottail darters do not participate in egg defense, but leave the nest site immediately after spawning. It is not known whether females spawn multiple times during a breeding season (fractional spawning) or just once.
Spawning and spent ovaries were found in the months of April and May and to some extent in October and November.
Gambusia nobilis occur at high densities in their native habitat and commonly aggregate around spawning pupfish pairs, suggesting that they might be preying upon newly deposited eggs of C.
Key words: aquarium, behavior, egg mass, fertilization, Lingcod, milt, Ophiodon elongatus, spawning