• Characterizing the fish community in turbid Alaskan rivers to assess potential interactions with hydrokinetic devices

      Bradley, Parker T.; Seitz, Andrew; Sutton, Trent; McPhee, Megan; Burr, John (2012-12)
      The Yukon and Tanana rivers are two large, glacially turbid rivers in Alaska, where hydrokinetic projects are being explored for feasibility of electricity production. Downstream migration behavior of fishes in these rivers is poorly understood; as a result, the potential impacts of hydrokinetic devices, which will be placed in the deepest and fastest part of the river, on fishes are unknown. Downstream migrating fishes were sampled during the ice-free season along the river margins of the Yukon River in 2010 and the river margins and mid-channel of the Tanana River in 2011. Results suggest that the river margins in the Yukon and Tanana rivers are primarily utilized by resident freshwater species, the mid-channel is utilized by Pacific salmon (Oncorhynchus spp.) smolts, and only chum salmon (Oncorhynchus keta) smolts utilize both of these areas. Some species exhibited distinct peaks and trends in downstream migration timing including longnose suckers (Catostomus catostomus), whitefishes (Coregonine), Arctic grayling (Thymallus arcticus), lake chub (Couesius plumbeus), Chinook salmon (O. tshawytscha), coho salmon (O. kisutch), and chum salmon. As a result of these fishes' downstream migration behavior, hydrokinetic devices installed in surface waters of the middle of the river channel will have the most potential interactions with Pacific salmon smolts during their downstream migration to the ocean from May through July.
    • Life history and spawning movements of broad whitefish in the middle Yukon River

      Carter, William K. III; Sutton, Trent; Brown, Randy; Lopez, Andres; Margraf, Joseph (2010-05)
      "Broad whitefish Coregonus nasus have long been an important subsistence resource across its Arctic and sub-Arctic range. Despite its regional importance, little is known about the life history and ecology of this species. This research illuminates fundamental life-history information through the use of catch-per-unit-effort (CPUE) run timing, gonadosomatic index (GSI), radio telemetry, and aging and microchemical analysis of otoliths. From 2001 to 2006, fishwheels were used to capture individuals 1,200 km upstream from the mouth of the Yukon River. CPUE data indicated a consistent increase in daily fish numbers through mid-September. The GSI showed an increasing gonad weight over the sampling period, indicating preparation for spawning. Thirty-one of 41 radio-tagged fish were tracked to a 260 km long spawning area centered 350 km upstream of the tagging site. Thirteen of 17 fish found in the spawning area in 2003 overwintered nearby. Ages of 79 individuals ranged from 5 to 16 years (mean age = 10; median age = 9). Microchemical analysis showed amphidromy in 10 of 12 individuals by examining otolith strontium (Sr) concentrations. This information indicates that the broad whitefish captured in this study were mature, migrating to a spawning/overwintering area, and have a complex amphidromous life history"--Leaf iii