In the USA contact:
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Powell, J.F.F.
1997. Synchronized Spawning of Wild and Captive Broodstock. Proc. 48th
Ann. Pacific Norwest Fish Culture Conference, Amer. Fish. Soc. 1-5, Dec.
1997, Salishan Ore. USA. |
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| In the natural course of salmonid
maturation, environmental cues are translated into physiological change.
This change is progressive and involves a cascade effect of hormones
initiated in the hypothalamus to the pituitary to the gonad. Salmon have
periods of susceptibility whereby the handling of maturing fish may cause a
cessation of the maturation process. As well, maturation will occur at
different rates in a large population and therefore fish will spawn at
different times. This serves to spread out the spawning season over a period
that is both species and strain specific. In some cases, spawning dates may
be asynchronous in races of fish that have limited returns to natal streams.
The results are similar: fisheries managers are left with stocks that are
not mature and will not synchronously mature. Under INAD and ESC (Canada)
approval we have developed a method to advance and synchronize maturation in
wild and captive broodstock. In a case study, coho salmon and seawater
rainbow trout were induced to mature using an implant placed in the dorsal
sinus of the fish. In treated fish, spawning dates were significantly
(P<0.05) advanced, milt production and viability was significantly increased
and fry were significantly quicker to first feeding. There were no
differences in mortality, egg size, fertilization rate or physical
characteristics within the stocks. In three INAD and three ESC trials, this
method has proven both safe (for humans and fish) and is effective. |
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