Main Ref. | Morrow, J.E., 1980 |
Mode | dioecism |
Fertilization | external |
Mating type | |
Spawning frequency | one clear seasonal peak per year |
Spawning aggregation | Ref. |
Batch spawner | Yes. Ref. Morrow, J.E., 1980 |
Reproductive guild |
nonguarders open water/substratum egg scatterers |
Parental Care | none |
Description of life cycle and mating behavior | Rainbow smelt usually return to natal streams to spawn but degree of homing varies from one population to another and may be genetically controlled (Ref. 11226, 30367). Movement into the streams begins when water temperatures reach 2° to 4°C or higher. The upstream run is generally short, at most a few km (Ref. 11226, 28996). Movement to spawning grounds are usually made at night. Males reach spawning grounds an hour or so before the females. Spawning is initiated, at least in part, by the presence of the proper sex ratio in the group, which has been indicated to be no more than four males to one female (Ref. 30366, 30374). The spawning group crowd together and move upstream. Body contact between a male and female brings about a release of sperm and eggs. Only a few eggs are extruded at each spawning act (Ref. 30366), so that the act is repeated over several hours each night for several nights until all eggs are extruded. After each evening's activities, most drift downstream to the larger body of water whence they came to the spawning grounds. Some, mostly males, may remain in the spawning stream during the day. Many spawned-out fish, especially males, die after spawning, but those that survive will spawn again the following year (Ref. 27547). Lake shore spawners on the other hand move inshore in small schools and swim about over rather restricted areas, apparently without any distinct pairing. The composition of the schools change constantly, for individual fish apparently engage in spawning activities for only 15 to 30 minutes at a time, then leave the school (Ref. 30374, 30376). |
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