The standing crop of brook trout in the study section was estimated 

 using a mark-recapture method (Table 25). The section supported approximately 

 602 fish representing a biomass of 29 pounds. Catchable fish (6 inches and 

 longer) amounted to 12 percent of the population. Brook trout condition 

 (length to weight ratio) was average for Mount Haggin streams and other upper 

 Big Hole River tributaries (MDFWP unpublished data). 



Table 25. Estimated standing crop of brook trout in a 1,000 

 Sullivan Creek (T2N, R12W, Sec 32A) on August 6, 

 percent confidence intervals are in parentheses. 



foot section of 

 1980. Eighty 



Species 



Length Range (inches) 



Per 1 ,000 ft. 



Number 



Pounds 



Brook Trout 



2.5 



4.0 

 7.0 



3.9 

 6.9 

 9.5 



258 

 324 

 19 

 602(+63) 29(+3) 



Sullivan Creek supported the second highest brook trout population of all 

 Mount Haggin streams surveyed; however, fish numbers were heavily concentrated 

 in the small size groups. Analysis of scale samples indicated that brook trout 

 growth was slightly slower than in other Mount Haggin streams although fish 

 condition was about average. A 50 foot section of Sullivan Creek (T3N, R12W, 

 Sec 30) was electrofished in 1976 (MDFWP unpublished data). Twenty-one brook 

 trout ranging in size from 2.8 - 8.0 inches were captured. As a result of 

 this survey, the fishery potential of Sullivan Creek was rated as good. 



4. FLOW RECOMMENDATIONS 



Cross sectional data were collected from a 74 foot riffle-run-pool 

 sequence located approximately at stream mile 2.6 (T2N, R12W, Sec 29CD). 

 Five cross sections were placed within this sequence. The WETP program was 

 calibrated to field data collected at flows of 50.1, 19.4 and 5.1 cfs. 



The relationship between wetted perimeter and discharge for a composite 

 of two riffle cross sections is shown in Figure 10. Lower and upper inflection 

 points occur at 4 and 5 cfs. Based on an evaluation of the existing fishery, 

 recreational use potential and contributory flow to the Big Hole River, a flow 

 of 4 cfs is recommended for the low flow period (July 1 - April 30). Due 

 to a lack of long term flow data, recommendations for the high flow period 

 (May 1 - June 30) cannot be derived. 



- 59 



