7926

• UCREFRP Catalog Number: 7926
• Author: Annear, T. C. and A. L. Conder.
• Title: Relative Bias of Several Fisheries Instream Flow Methods.
• USFW Year: n.d.
• USFW - Doc Type: Cheyenne, Wyoming.
• Copyright Material: NO

me thods may provide useful MF recommendations.

However) for the quality

fishery needs.

Although wetted perimeter methods are incapable of document

biological trade-offs over a range of flows) the conscientious use of

data, users may wish to consider using one of the habitat retention methoqs

slnce the same model is used for both and the habitat retention methods incor-

parate other biologically related information with wetted perimeter data.

The habitat retention methods offer distinct advantages over both of the

previously discussed methods.

Recommendations are defensible" incorporate

biological data into cri teria development ,snd, at leas t indirec tly) identify

some trade-offs.

Al though the cri teria used here relate to trout in general)

they may be changed easily to address unique environments or species where

appropriate data are available.

,,, '---i'""""',
--_-w'

The four PHASIM methods did not provide consistent (high, low) or unbiased)

threshold recommendations.

It would be presumptive) however) to equate incon-

sistency with inaccuracy.

Inconsistent methods may, in fact) be more biologi-

cally accurate than methods we found to have significantly consistent tenden-

cies.

The PHABSIM models incorporate more fish habi~at components than the

other methods in this'study and the observed inconsistencies may be reflecting

unique habitat characteristics of thes treams.

It may also indicate that the

method(s) is not suited to every situation.

Our research to date has shown

that, where the assumptions associated with these models are met (primarily that

depth, velocity, and substrate are independent and are the most limiting

variables affecting the fishery),

the models are generally capable of

illustrating the impact of various flows on trout habitat (unpublished infor-

mation from Conder and Annear) Wyoming Game and Fish Department). This presents

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