Study Predicts Climate Change Threatens Trout Habitat

A study by researchers from the U.S. Forest Service, the U.S. Geological Survey, Colorado State University, the University of Washington and Trout Unlimited found that climate change will likely cause a 50% decrease in trout habitat by 2080 in the western United States. Warmer temperatures as well as changes in stream flow and interactions with competing species were all named as contributors to the decline.

The Cutthroat Trout (Oncorhynchus clarkii), the only trout species native to much of the West, is projected to be the most drastically impacted. The Westslope Cutthroat Trout (Oncorhynchus clarkii lewisi), a subspecies, is the Montana state fish and has inspired numerous conservation efforts.

Cutthroat Trout (Oncorhynchus clarkii)

TNACI scientists share a similar focus on the Southern Appalachian Brook Trout (Salvelinus fontinalis) – the only trout species native to Tennessee. Last October, TNACI began a propagation study of the Brook Trout, funded by a grant from the National Fish & Wildlife Federation. Adult brood stock were collected from Hampton Cove Creek and brought back to TNACI where gametes were stripped and eggs were fertilized. The baby brook trout that hatched from the eggs are currently growing strong and will be released in August back into the river from which their parents were caught. This species is sensitive to increasing water temperatures and has a maximum temperature tolerance of 55 degrees Fahrenheit.

Brook Trout (Salvelinus fontinalis)

 

Reviewers of the climate change study note that Montana’s high elevation and northern positioning may help to buffer some of the effects that may be magnified in other regions. This is particularly significant to TNACI’s work which focuses on conserving freshwater habitats in the Southeast - which may not experience this buffering when it comes to climate change. 

TNACI Awarded Grant for a New Conservation Program

For the last 14 years, the Tennessee Aquarium Conservation Institute and its partners have been working diligently to rear Lake Sturgeon in captivity and reintroduce them into the Tennessee River.  For the last three years, we have worked with Conservation Fisheries Incorporated to breed endangered Conasauga Logperch in captivity and augment their populations in Tennessee and Georgia.  This year, TNACI was awarded a grant from the National Fish and Wildlife Foundation to create a new propagation program.

Photo of a Southern Appalachian Brook Trout in its natural environment.  Photograph by Dave Herasimtschuk. 

Southern Appalachian Brook Trout  (SABT) in Tennessee and North Carolina are distinct from the Brook Trout found elsewhere in the United States because they have been geographically isolated from their northern relatives for thousands of years.  They are under threat from habitat degradation and invasive species introduction.  Historically, they lived in cool, fast flowing streams in the southern Appalachian Mountains. Logging and agricultural practices, however, have decimated Appalachian forests, which in turn harm the waters where brook trout live.  When surrounding forests are lost from creeks, water temperature rises, oxygen levels drop, and siltation from erosion increases, all resulting in streams that can no longer support brook trout.  In addition, introduced populations of rainbow trout, brown trout, and even northern brook trout compete with native SABT for the most high quality habitat.  In the Southeast, only 3% of historic watersheds support SABT populations.  

Conservation measures for this fish have been underway over the last few years at other hatcheries in the Southeast.  However, we at TNACI are attempting to take a different approach.  In general, trout hatcheries (and hatcheries for other fish) operate on flow-through systems.  When TNACI was located in Cohutta, GA, our Lake Sturgeon were in a flow-though system.  While this is energy efficient and has the potential for housing large numbers of fish, disease transfer and escapees can be a problem.  This grant will help TNACI develop techniques for rearing SABT in recirculating systems that drastically reduce disease transfer and escape concerns.

With assistance from our partners (Tennessee Wildlife Resources Agency, the U.S. Fish and Wildlife Service, and the U.S. Forest Service) we have collected 50 Brook Trout for brood stock.  This is a beautiful fish, especially during the fall when they spawn.  All year, the fish have red spots along their sides, and their pectoral, pelvic and anal fins are red with a white leading edge.  But when spawning season arrives, the red coloring becomes much more pronounced.  

SABT in July

SABT in October

We have already stripped some of our SABT of their gametes (eggs and sperm).  It is a delicate process that involved gently squeezing the trout.  Once fish were stripped, 1% saline was added to the eggs and sperm and the solution stirred with a turkey feather.  The turkey feather is an old tradition that has been used for decades in fish hatcheries.  Now that the eggs have been fertilized they are being held at TNACI until they hatch, which takes about two weeks.  We should have babies (larval SABT) very soon!

Stripping a SABT and taking a fin clipping

Fertilized trout eggs