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Fish - Inducing Reproduction - Anatomy & Physiology (view source)
Revision as of 07:03, 30 July 2008
, 07:03, 30 July 2008no edit summary
== Introduction ==
== Introduction ==
Where successful, techniques for altering the spawning cycle of fish have become a valuable tool.
Where successful, techniques for altering the spawning cycle of fish have become a valuable tool.
== Strategies ==
There are two main strategies used to induce reproduction.
* The first is to provide an environment similar to that in which spawning occurs naturally. ** Catfish, for example, like to spawn in enclosed spaces such as hollow logs. A farmer can simulate this by putting milk cans in a pond.
** The presence of vegetation and an increase in temperature will usually work for goldfish. ** Changing the photoperiod in a hatchery can accelerate or delay maturation and ovulation in many salmon and trout species.
* The second strategy is to inject the fish with one or more naturally occurring reproductive hormones or their synthetic analogues.
* This is only effective in fish that are already in breeding condition and have mature eggs in which the germinal vesicle has migrated.
* Often the two strategies are used sequentially: the first to manipulate maturation, then the second to induce ovulation.
Numerous hormones have been used to induce reproduction. Two methods have emerged over the past few years that seem to offer the best chance for success at the least expense. They are injection of a GnRH analog with dopamine antagonist, and injection of gonadotropin.