Growth ■ During the 1975 and 1976 spawning runs, 151 sturgeon were recap- 

 tured after having been at large 12 to 24 months. Empirical growth rates were 

 divided into years and types of tags to assess differential growth rates as 

 related to type of tagging. Sturgeon tagged with anchor tags lost an average 

 of 1.5 mm (0.06 in) from 1974 to 1975 and gained an average of 2.2 mm {0.2 in) 

 from 1975 to 1976 and 1.4 nm (0.06 in) in length from 1974 to 1976. Only the 

 gain from 1975 to 1975 was significant (p'^.02). 



Shovelnose sturgeon tagged with monel tags showed significant length loss 

 for each year. Fish tagged in 1974 and recaptured in 1975 lost an average 

 7.0 mm (0.3 in) while those tagged in 1975 and recaptured in 1976 lost an 

 average of 5.2 mm (0.2 in). Average loss from 1974 to 1976 was 8.0 mm (0.3 in). 

 All losses were significant (p<.01). Apparently the monel tag resulted in 

 physiological change drastic enough to alter the growth rate of the sturgeon. 



No conclusions could be made concerning the growth of shovelnose sturgeon 

 based on individually marked fish because of the weight loss associated with 

 the use of monel tags. 



SAUGER 



Sauger {Stizostedion aanadense) and walleye ( Stizostedion vitreum) are 

 important to the sport fishery of the lower Yellowstone River. Native to 

 Montana, the sauger inhabits the Missouri River drainage below Great Falls 

 and the Yellowstone drainage below Billings. It was first recorded in 

 Montana by the Lewis and Clark Expedition (1804-1806). Preferred habitat 

 for sauger includes turbid rivers and shallow portions of lakes and reservoirs. 

 Sauger generally spawn in gravelly or rocky areas in the spring when tempera- 

 tures reach 4.4-10.0°C (40-50°F). Fish migrate upstream to spawn, often 

 moving into tributary streams. 



A sauger spawning run occurs in the Tongue River, with fish moving out 

 of the Yellowstone in the spring. This migratory population offers an 

 excellent opportunity for anglers to pursue the sauger. Sampling in the 

 spring of 1974 indicated that large numbers of fish enter this run. Early 

 high water, coupled with above-normal sedimentation, prevented good sampling 

 in 1975. However, in 1976, a mild spring provided good sampling conditions, 

 and a large sample was collected. 



FISH SIZE 



Length-Weight Relationship 



In 1976, 1004 sauger were taken in the lower Tongue River. Lengths and 

 weights were recorded for 1001 of these. The average length and weight of 

 the total sample was 379 mm (14.9 in) and 441 g (0.97 lb), respectively. Sexes 

 were differentiated by the presence of milt for males and/or a distended 

 abdomen and protruding ovipositor for females. Ripe males were common in 

 the sample, but no ripe females were taken. Males dominated the sample, 

 contributing 85.7 percent, while females added 3.2 percent. The remaining 

 11.1 percent were of undetermined sex. Females were larger than males, 



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