Re: {Tidal Potomac Fly Rodders} Re: Difficult Run

Tom - I figured it out - Troop 1983.

On Fri, Apr 20, 2018 at 9:30 PM, Tom Moran <twmoran19@gmail.com> wrote:

Hi Tom, thanks for dropping in.  Your name really sounds familiar to me, and I've never been a member of TU.  Potomac River Smallmouth Club perhaps?  

Some of the comments in the thread indicate brook trout were found upstream from the Dulles Toll road.  John Odenkirk thought that the death knell for those small and isolated populations was the Government Center complex just upstream from Fair Oaks Mall, which itself must have been a significant impact to the watershed.  It sounds like you were also aware of a downstream population.  

Best,

Tom

On Fri, Apr 20, 2018 at 11:12 AM, <tguffain@verizon.net> wrote:

From my time as a Director of the Northern Virgina Trout Unlimited in the 80s it was known that there were Brook Trout in Difficult Run.  There was a Professor from George Mason University along with graduate students  who were studying these trout.  From my discussion with them the last residual population disappeared when the Dulles toll road was constructed over Difficult Run.

Below is the Abstract from an article published in 1992 in the Journal of the Pennsylvania Academy of Science by Jeffrey E Jovich entitled "Aspects of the Ecology of an Isolated Population of Brook Trout (Salvelinus Fontinalis) in Fairfax County, Virginia".

Abstract
An isolated population of brook trout (Salvelinus fontinalis) appears to have survived in the headwaters of Difficult Run, Fairfax County, Virginia since at least 1899 when they were first reported. The presence of brook trout in Difficult Run is unusual for two reasons: 1) Difficult Run is the only stream in the area known to have been inhabitated by brook trout for so long, and 2) they are apparently the only potentially self-sustaining population of native trout in Virginia's Piedmont Province. Brook trout were sampled from 1979 to 1981 with electroshocking gear. The sex ratio was not significantly different from unity. Juveniles accounted for 38 percent of the sample. The modal size class was between 115-135 mm total length. Mean total length and weight of males and females was not significantly different. A multiplicative function suggests that weight increases at significantly less than the cube of total length, unlike most other brook trout populations. The population in a 410 meter section of stream was estimated at 65 fish. Gut contents consisted primarily of plecopterans and coleopterans. Movements of marked fish ranged from 20-150 meters between capture intervals of 7-128 days. Spawning probably occurs in November. The brook trout of Difficult Run may be a relic of a previously more widespread distribution of native trout.

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