PKOGRESS IN BIOLOGICAL INQUIRIES, 19 31 509 



TETON NATIONAL, PARK INVESTIGATION 



The biological survey of the waters of the Grand Teton National 

 Park is the first of a series planned for the national parks in order 

 that systematic stocking; ])lans for these waters nia}'^ be devised. 



Field work was conducted from July 20 to September 20. An 

 exchange of personnel was effected betw^een the members of the 

 "Wasatch and Teton survey parties for a part of the season in order 

 that the work in these areas might be better coordinated. 



Six lakes, from 60 to 1,360 acres, wdth a total area of 3,443 acres, 

 afford the principal fishing in this park. The streams within the 

 park are too small and precipitous to afford much angling, although 

 they are extremely important in furnishing the only successful 

 spawning grounds for the cutthroat trout of the lakes. 



Studies of aquatic plants, plankton, littoral, and benthic organisms 

 w^ere made. Studies of temperature, depth, type of bottom, and 

 clemical relations were undertaken. The fish population w^as in- 

 vestigated, and collections of fish stomachs and scale data secured 

 from 145 specimens of cutthroat trout. A preliminary survey of 

 Jackson Lake was also made which included extensive soundings and 

 fish collections. 



A systematic stocking plan is being formulated for these waters 

 based upon the data secured during this survey. 



With two exceptions, the lakes of this area were found to contain 

 considerable water over 50 feet in depth. Abundance of oxygen 

 and small amounts of carbon dioxide w^ere found in all but one of 

 these lakes. The large volume of the cold tributary streams and 

 the scarcity of organic material are responsible for this condition. 

 The waters of the park are acid for the most part and contain small 

 quantities of bicarbonates, with the exception of the southernmost 

 lakes and streams which drain some areas of limestone formation 

 in contrast to the igneous and metamorphic rock which make up 

 the drainage areas of the more northern waters. A marked su- 

 l^eriority in the quantity of aquatic fauna and flora was noted in 

 these more southern waters. 



The present reduction in the trout populatioji in the Teton lakes 

 is believed to be due to the increase in angling, lack of sufficient 

 artificial plantings, and to the scarcity of suitable spawning beds 

 for the cutthroat trout. Gill netting, seining, and observation failed 

 to show the presence of young trout, smaller than 7 inches in the 

 lakes, although fry and fingerlings were common in the inlets and 

 outlets of the lakes. Impassable falls near the lakes limit the spawn- 

 ing areas to a few hundred yards in most cases. Consistent stocking 

 should show a marked improvement in the angling in these lakes in 

 the near future. 



Studies of 109 cutthroat trout of lakes and 36 of streams show a 

 marked difference in the food habits of this species, depending upon 

 size and environment. Fish are unimportant in the diet of stream 

 trout of the sizes taken, due in part to the scarcity of this type of 

 food here. Aquatic insects formed approximately 75 per cent of 

 the food ; terrestrial insects 25 per cent. In lake fish aquatic insects 

 formed 3 per cent by volume, terrestrial insects 7 per cent, plankton 

 Crustacea 10 per cent, and fish 60 per cent, indigestible and unidenti- 

 fied material contributing the balance. Fish formed the larsest 



