18 



COMMERCIAL FISHERIES REVIEW 



Vol. 28, No. 9 



Inland Fisheries Explorations 

 and Gear Development 



OAHE RESERVOIR TRAWLING 



STUDIES CONTINUED: 



Reservoir Research Vessel " Hiodon " 

 Cruise 7 (June 1966): To delineate areas for 

 effective bottom trawling and collect catch 

 and biological data was the purpose of these 

 explorations in the Oahe Reservoir located 

 on the upper Missouri River in North and 

 South Dakota. Trawling operations by the 

 reservoir fishery research vessel Hiodon, 

 which is operated by the U. S. Department of 

 the Interior's Bureau of Commercial Fish- 

 eries, were conducted in zones 1-6. 



FISHING OPERATIONS: A total of 74 drags 

 was made with 35, 45, and 52-foot (headrope) 

 trawls. Drags totaling 51 were of 15 min- 

 utes duration, 5 of 10 minutes duration, and 18 

 of 5 minutes duration. A total of 7 of the 

 drags was made at night. Another 9 drags 

 were incomplete because of fouling of the net. 



Seven drags were made for the primary 

 purpose of effecting trawl modification and 

 testing the results; 8 drags were made pri- 

 marily for the collection of biological data; 

 17 drags were made to test for differences 

 between day and night catches; and 42 drags 

 were for exploration of trawling grounds and 

 checking fish distribution. 



Shows trawl containing catch being lifted aboard reservoir fishery' 

 research vessel Hiodon. 



FISHING RESULTS: The 74 drags took a 

 total of 8,702 adult fish weighing 7,853 pounds 

 for an average of 118 fish or 106 pounds per 

 drag. Carp comprised 77.4 percent of the 

 catch by weight; yellow perch, 6.2 percent; 

 bigmouth buffalo, 3.5 percent; and carp- 

 suckers, 3.2 percent. Other species ac- 

 counted for less than 2.0 percent of the catch. 



A 45-foot headrope trawl required minor 

 changes to correct a tendency toward twist- 

 ing of the cod section. Correction was 

 achieved by placing floats on the top side of 

 the cod. The combination of experimentation 

 and dragging on flats resulted in a low catch 

 rate of only 39 pounds per drag. Species 

 composition of the catch was 90 percent carp, 

 3 percent burbot, and 2 percent drum. 



The 8 "biological drags" yielded a total 

 of 1,400 fish that weighed 857 pounds for an 

 average of 107 pounds per drag. Data rel- 

 ative to length-weight relationships, scale 

 samples, and other biological information 

 obtained was to be used in biological studies. 



Ten daytime drags and 7 nighttime drags 

 were made as an experiment to determine 

 whether there is a significant difference in 

 the rate of catch or species composition of 

 catches made at different times of the day. 

 During the cruise, drags made during day- 

 time caught an average of 66 pounds a drag 

 and nighttime drags caught an average of 82 

 pounds a drag. Carp made up 79 percent of 

 the daytime catch (by weight) and 60 percent 

 of the nighttime catch. Drum, carpsucker, 

 bigmouth buffalo, and white crappie made up 

 a slightly higher percentage of the night 

 catches. Perch accounted for less than 2 

 percent of the daytime catch, but comprised 

 13 percent of the nighttime total. 



Of some interest was the large increase 

 in yearling fish caught at night. An average 

 of 13 yearlings per drag entered the daytime 

 catch as compared to 154 per drag at night. 

 The large increase resulted primarily from 

 the increased catch of yearling bullheads (2 

 per drag during daylight; 81 per drag at 

 night), white crappie (5 - 37) and perch (2- 

 26). Comparison of daytime and nighttime 

 catches will continue through the 1966 field 

 season program. 



A total of 2,080 yearling fish was caught 

 during the cruise. The species composition 

 was 53 percent perch, 19 percent bullheads, 

 10 percent white crappie, 5 percent yellow 

 pike (walleye), 4 percent sauger, 3 percent 

 northern pike, and 2 percent white bass. 

 Other species taken were goldeye, black 

 crappie, drum, carp, carpsucker, channel 

 catfish, and burbot. 



Note: See Commercial Fisheries Review . August 1966 p. 34. 



