ESTIMATING ENERGY EXPENDITURE AND TOTAL BODY WATER CONTENT OF FISHERS IN CALIFORNIA WITH DOUBLY LABELED WATER.
Aaron N. Facka; , OR; (575) 650-7880; anfacka@gmail.com; Roger A. Powell
The current understanding of fisher energetics is still largely hypothetical because no estimates of energy have been taken in the field from wild fishers. We used the Doubly Labeled Water (DLW) method to estimate energy expenditure of fishers in their natural environments. In the autumns of 2012 2017 we enriched 54 (36 F; 18 M) wild caught fishers with DLW. Background levels of 2H and 18O in fishers were 148 ppm and 1989  ppm and we enriched fishers to an average of 407 ppm for 2H and 2395 +/- 68 ppm for 18O. We released all enriched fishers back into the wild and recaptured 32 of them (60%; 20 F; 12 M) 2 to 13 days later. Fishers were recaptured an average of 4.5 +/- 2.9 days after enrichment. Twenty one (65%) fishers lost weight (-0.10 +/- 0.19 kg). Estimates of total body water were consistent over time and similar for female (0.73 +/- 0.04) and male (0.72 +/- 0.035) fishers. From preliminary analysis, energetic expenditure for fishers was 585 kcal/day (1.5 times higher than the reported maintenance cost of active fishers). Estimates of energy have important implications for management of species as conditions change.
Ecology and Conservation of Martens and Fishers