Summary: The Effects Of Rivalry On Wild Salmon Populations

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The Effects of Hatcheries on Wild Salmon Populations

Salmonids are perhaps one of the most prominent fish in freshwater systems such as streams and lakes. Their success can be widely attributed to their anadromous lifestyle. However, despite their success, salmonid populations are on a continuous decline. Many species such as Pacific Salmon in Washington, Oregon, and California are critically endangered, while some are threatened with extinction due to several different factors (Moyle and Cech, 2004). In the wild, habitat destruction and land transformation of salmonid spawning locations have detrimentally affected wild populations. Construction of dams alter flow regimes and flow rates and prevents anadromous salmon from reaching spawning
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Hatchery-reared salmon and wild-reared salmon breeding together results in genetic outbreeding depression. Outbreeding depression occurs when the offspring exhibit lower reproductive success and chances of survival than their parents in the local environment. Wild salmon populations have developed traits over generations that allows them to adapt and thrive in their natural habitats. When populations of wild salmon and hatchery-reared salmon are crossed together their offspring may possess traits that may be detrimental to their survival in the same habitat. Hatchery raised male salmon only have 51% of the reproductive success that wild salmon exhibit. (Neff et al, 2015) Hatchery raised salmon exhibit reproductive behaviors that differ widely from wild salmon that result in hatchery males fertilizing 62% as many eggs as wild males (Neff et al, 2015.) Although this could mean less reproductive competition for wild male salmon, that trait could spread throughout hybrid salmon populations and lead to a reduction in salmon populations due to the high reproductive failure

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