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

transects placed across one or more riffles.

I t is then inferred

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This method is most often used by analyzing wetted perimeter curves

instream flow at that riffle (or average of several riffles) will also be ade~

quate for all other habitats. Other users (Nelson 1980) have similarly analyze~

curves from all habitat types within a stream reach.

A major drawback with this method is that inflection points are chosen

solely on a subjective basis and recommendations can vary between investigators.

Complications also arise when no clearly defined inflection is found or where

multiple inflections occur on a curve. As the name of the method implies, sub-

j ec tive me thods reflec t the user's bias to some degree.

This does not imply

that bias is always a detriment.

In this study, MF recommendations were based on mean wetted perimeter curves

for riffles as well as for all habitat types (Table 1).

Recommendations were

obtained by subjectively identifying inflection points as well as by development

of a more objective testing procedure.

One-way analysis of variance (ANOVA) was performed on each data set that was

used to define a mean "wetted perimeter curve.

Where statistical significance

was found, a multiple mean comparison, Fisher's least significant difference

(LSD) (Snedecor and Cochran 1971), was used to identify statis tically signifi-

cant reductions in wetted perimet~t from predefined reference flows. Reference

flows were (1) two times the AF, using Tennant's proposal that this is a maxi-

mum desired flow and (2) AF, again using Tennant's proposal that this is an

optimum flow.

A total of six wetted perimeter methods resulted from these

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