Tuesday, August 4, 2015

When poison is necessary to restore native trout

Native trout in today's cold-water ecosystems must cope with numerous threats that include habitat loss, pollution, climate change, recreational fishing pressure, and competition with stocked non-native trout.  As native trout have continued to lose ground many (sub)species have been petitioned for listing under the Endangered Species Act of which six have been listed.  And as presented by Trout Unlimited's State of the Trout report, excluding already extinct trout, more than 50% of the remaining (sub)species occupy less than 25% of their historical habitat.

State and federal agencies along with local stakeholders and non-profit conservation groups have collaborated to protect and restore native trout throughout their historical habitat.  One of the tools utilized to restore native trout to habitat that has been lost to non-natives stocked for recreational opportunities is the piscicide rotenone.

Rotenone is used to completely cleanse a waterway of fish (and typically any other organism that relies on gills to breath including tadpoles, non-adult salamanders, and macro-invertebrates) in order to make way for native fish to be restored to the waters.  Typically a water is treated more than once in order to ensure that non-natives aren't hiding in some watery nook or cranny waiting to refill the now open environment with its own progeny that would once again compete with the native trout that are being restored.

A great example of the use of piscicides such as rotenone to restore native trout can be found in the waters of Yellowstone National Park (YNP).  In 2011, YNP published a Native Fish Conservation Plan, which set the stage for the restoration of genetically pure Yellowstone cutthroat trout (Oncorhynchus clarki bouvieri) to Soda Butte Creek later this year.  Rotenone will be utilized to remove non-native brook trout (Salvelinus fontinalis) from Soda Butte Creek, which is a tributary to Yellowstone's famous Lamar River, making way for Yellowstone cutthroat trout.

The use of piscicides in support of native trout restoration is a well established management tool in fisheries management.  But, like so many government actions, the removal of non-natives with the use of poison is often met with vocal and at times radical resistance.  I can fully understand how the use of lethal methods may seem antithetical to conservation efforts.  However, until technology bequeaths us a more effective means of non-native removal and native trout continue to brave today's overwhelming synergistic threats, the use of piscicides must continue to serve as a conservation tool.

I suspect that this entry may engender rather vitrolic responses as the use of poison in nature brings with it heated rhetoric.  Nevertheless, this is a topic that is too important to native trout conservation to go unaddressed.  So until next time, let the vitriol flow!
Cheers,
Brad

You can also find my discussions on fly fishing and conservation issues at-
Twitter- @conservationfly
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