Date of Award
Carl R. Reutz III
Remote site incubators (RSIs) have been used to rear salmonid fish eggs along streams in the Pacific Northwest since the 1980s. Recently, the successful use of RSIs for Arctic Grayling Thymallus arcticus restoration in Montana has sparked a renewed interest to reestablish the species in Michigan. To support future reintroduction efforts of Arctic Grayling in Michigan, I evaluated RSIs in three Michigan streams during 2018 and 2019 using Rainbow Trout Oncorhynchus mykiss eggs (as surrogates for Arctic Grayling). My objectives were to: (1) compare hatching success between two different RSI designs (19-L vs. 265-L RSIs), and (2) test whether the removal of dead eggs (“picking”) from 19-L RSIs affected hatching success. Overall survival (i.e., hatching success of all RSIs) in 2018 and 2019 was 41.3% and 52.4%, respectively. Survival between unpicked 19-L and 265-L RSIs by stream differed from 1.5% to 14.3% (mean = 5.8%) in 2018 and 0.2% to 0.4% (mean = 0.3%) in 2019. On average, the picked 19-L RSIs had greater survival—although not always statistically significant—than unpicked 19- L RSIs during both years (2018: mean = 1.6%, P = 0.27; 2019: mean = 10.4%, P = 0.02). I documented a positive correlation between survival and RSI flow rates, and a decline in survival when RSI flow rates could not be maintained above ~0.4 L/min. My results show that both 19-L and 265-L RSIs can be used successfully in Michigan streams. Moreover, my results suggest that removing dead eggs was most likely to improve survival when RSI flow rates cannot be maintained above 0.4 L/min.
Mock, Alan J., "Evaluating remote site incubators to support restoration of Arctic Grayling in Michigan" (2019). Masters Theses. 958.