Tiber Reservoir | North Fork Preservation Association

Mussel-fouled Propeller - NPS photo — Mussel-fouled Propeller – NPS photo

Invasive mussel DNA is still being found in Tiber Reservoir, but no larvae or adults so far . . .

Samples taken last year from Tiber Reservoir bolstered older evidence for the presence of invasive mussels.

In a press release Thursday, Montana Fish, Wildlife and Parks announced that samples of environmental DNA (eDNA) taken by it and the U.S. Geological Survey during 2017 indicated invasive mussels’ presence in Tiber Reservoir.

In Fall 2016, the discovery of quagga mussel larvae and a shell fragment there triggered a massive effort to detect and contain the animals. Over the course of 2017, the press release states, “FWP and partner agencies collected more than 1,500 plankton samples from 240 waterbodies,” including 128 plankton tow samples from Tiber and 147 at Canyon Ferry, where their presence is suspected.

Through these tests, “no adult mussels or larvae were found.”

Read more . . .

This is encouraging news. A search at one of the first places in Montana to test positive for invasive mussels last year turned up no evidence of adult mussels last week.

From the press release . . .

Divers searched for adult aquatic invasive mussels at Tiber Reservoir last week, but found none.

The five divers involved in the effort were from the U.S. Fish and Wildlife Service and coordinated by Montana Fish, Wildlife and Parks. The primary search area was Tiber Dam up to a depth of about 35 feet.

With its rock structure, the dam is good habitat for the invasive mussels, which prefer solid substances, like rocks, to attach to. However, deeper than 35 feet, silt reduced the habitat significantly.

The divers are part of FWP’s monitoring plan for Tiber Reservoir after water samples last year came back positive for aquatic invasive mussel larvae. The monitoring plan also includes an increased frequency of water sampling at the reservoir.

The divers also searched rock outcroppings around Turner Point at Tiber Reservoir. No adult invasive mussels were discovered.