Trout and fire: once bitten, twice burned. . .

By John Zablocki & Helen Neville, TU Lahontan Cutthroat Trout Conservation Team

Nobody wants to get burned, trout included.  But fires and other disturbances such as drought, disease, floods and freezes are all natural parts of the trout’s ecosystem.  Generally, trout are well-equipped to handle disturbances, often by moving to unaffected areas either within a stream or in a different stream where they can wait until conditions improve.  Even though fires can be huge in scale and seemingly disastrous, they don’t always burn everything in their path – in some cases they jump right over streams if willows and other stream vegetation are in good enough shape to resist the fire, providing the fish with ‘hiding spots’ within the charred landscape.  Also, where streams are connected to each other, if a fire wipes out one population, trout from elsewhere can eventually find their way through the watershed to replace it…or at least they could, before humans started breaking up and degrading their habitats, which is now the case for Lahontan cutthroat trout (LCT).

Historically, watersheds home to Lahontan cutthroat trout were well-armored with stream-side vegetation and were inter-connected, allowing the trout to weather almost any storm.  But today, habitat degradation from grazing and other activities, along with the erection of barriers such as road culverts, irrigation canals, and dams, have fragmented the fish into isolated areas with small populations.  This scenario has severely limited the fish’s ability to respond to fire and other disturbances, preventing the proper functioning of their ‘ecological immune system', so to speak.  And with climate change already increasing the frequency and intensity of disturbances such as fires and drought, LCT and other native trout are likely to get twice burned: more fires, less ability to cope with them.

This year is already shaping up to be the one of the worst drought and fire years in history, and the Lahontan cutthroat trout is feeling it intensely.  The Holloway fire, a wildlife burning at the border of northern Nevada and southern Oregon has already burned nearly a half million acres.  This and another fire further east, the Willow fire, have burned up large portions of three of the largest habitats remaining for LCT across their range.

Fortunately, TU, along with numerous partners, has been involved in restoration and monitoring work in several of the recently burned watersheds, giving the fish a better chance of survival.  By improving grazing strategies to allow stream vegetation to recover and removing barriers to fish passage in order to reconnect the watersheds, we and our partners are actively restoring resiliency to the landscape—helping the fish help themselves.

Reconnecting watersheds improves more than just the physical environment for the fish.  When trout waters are fragmented, the isolated populations lose genetic diversity.  Restoring the connectivity of previously isolated populations helps restore this diversity, allowing the fish to better adapt to a changing environment in the future – similar to how a diversified investment portfolio helps an investor endure unpredictable changes in the market.

With the double hit of drought and fire this year, the fish will certainly have their work cut out for them. The impact of the

Holloway and Willow fires has yet to be determined. We are already planning post-fire monitoring to evaluate the impact of the fires on the fish, and we will be assisting with more active management of LCT, such as translocations and restoration, where needed.  Hopefully our long history of collaborative restoration and continued involvement in these recently-burned watersheds will give the fish a fighting chance.   They’ll need it now more than ever.