Spring chinook salmon, Oncorhynchus tshawytscha, in the Snake River Basin
are listed as endangered under the Endangered Species Act. The typical life history of spring
chinook salmon is semelparous. An experiment was performed to see if mature male spring
chinook salmon parr could be reconditioned after hand-spawning and spawned in successive
years. The mature male parr were part of a 1997 and 1998 cohort of captive broodstock from
the Grande Ronde River Basin in Oregon. Force-feeding was combined with volitional
feeding in an attempt to inhibit senescence and increase survival time after spawning. The
viscerosomatic index, fat and protein contents increased with survival time after spawning
for both cohorts. There was a significant relationship between percent weight change and
survival time for the 1997 cohort (p<0.001). Force-feeding had no effect on survival time
after spawning for the 1997 cohort (p=0.074) or the 1998 cohort (p=0.178). Fat content,
weight gain and survival time indicated that the reconditioning process was observable in the
1997 cohort at 77 days after spawning and was cyclical, resulting in a physiological response
which allowed male chinook salmon to spawn in successive years. Fertilization trials with
three reconditioned males yielded a fertilization success rate of 96.9% compared to 95.7% for
4-year old, anadromous male spring chinook salmon (p=0.152), measured as production of
eyed-embryos. This experiment provides new knowledge of plasticity in the reproductive
biology of male, stream-type, spring chinook salmon. Reconditioning and spawning male
chinook salmon parr in successive years could be used to help maximize genetic diversity and
aid in the recovery of endangered Oncorhynchus populations. / Graduation date: 2002
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/32675 |
| Date | 16 April 2002 |
| Creators | Mayer, Kent Corey |
| Contributors | Liss, William J., Dickhoff, Walton W. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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