Research about Kuskokwim Bay

USGS2018

Energy allocation and feeding ecology of juvenile chum salmon (Oncorhynchus keta) during transition from freshwater to saltwater

Pacific salmon (Oncorhynchus spp.) populations near their northern range extent in the Arctic-Yukon-Kuskokwim region of Alaska have undergone major changes in population trajectory and illuminated the lack of basic information on juvenile ecology. This study fills information gaps on the early life history of chum salmon at northern latitudes. Energy allocation was examined in the context of distribution, feeding intensity, and diet during a critical life history period for a single cohort of juvenile chum salmon (O. keta) as they transition from freshwater to saltwater in Kuskokwim Bay from mid-May to early June. Juvenile chum salmon were primarily captured in the river mouth and plume. Energy density (kJ g−1 dry mass) was related to fork length, timing (day-of-year), and capture location in a general additive model. The smallest fish had slightly higher energy densities, but the change in energy density with fish size was minimal and consistent with allocating energy toward somatic growth rather than lipid storage. Fish captured earlier had higher energy density, likely reflecting the presence of residual yolk lipids during early migration. Fish captured in the river mouth and plume had higher energy densities. Feeding intensity was highest among small fish captured later within the river plume. Diet was dominated by surface prey (insects and calanoid copepods) rather than epibenthic harpacticoid copepods as commonly observed. These results provide the first data on energy allocation of juvenile chum salmon during a critical life history phase and suggest that somatic growth is prioritized over storing lipid at saltwater entry.

Alaska↗

USGS2013

Reconnaissance geologic map of the Kuskokwim Bay region, southwest Alaska

The rocks of the map area range from Proterozoic age metamorphic rocks of the Kanektok metamorphic complex (Kilbuck terrane) to Quaternary age mafic volcanic rocks of Nunivak Island. The map area encompasses much of the type area of the Togiak-Tikchik Complex. The geologic maps used to construct this compilation were, for the most part, reconnaissance studies done in the time period from the 1950s to 1990s. Pioneering work in the map area by J.M. Hoare and W.L. Coonrad forms the basis for much of this map, either directly or as the stepping off point for later studies compiled here. Physiographically, the map area ranges from glaciated mountains, as much as 1,500 m high, in the Ahklun Mountains to the coastal lowlands of northern Bristol Bay and the Kuskokwim River delta. The mountains and the finger lakes (drowned fiords) on the east have been strongly affected by Pleistocene and Holocene glaciation. Within the map area are a number of major faults. The Togiak-Tikchik Fault and its extension to the northeast, the Holitna Fault, are considered extensions of the Denali fault system of central Alaska. Other sub-parallel faults include the Golden Gate, Sawpit, Goodnews, and East Kulukak Faults. Northwest-trending strike-slip faults crosscut and offset northeast-trending fault systems. Rocks of the area are assigned to a number of distinctive lithologic packages. Most distinctive among these packages are the high-grade metamorphic rocks of the Kanektok metamorphic complex or Kilbuck terrane, composed of a high-grade metamorphic orthogneiss core surrounded by greenschist and amphibolite facies schist, gneiss, and rare marble and quartzite. These rocks have yielded radiometric ages strongly suggestive of a 2.05 Ga emplacement age. Poorly known Paleozoic rocks, including Ordovician to Devonian and Permian limestone, are found east of the Kanektok metamorphic complex. A Triassic(?) ophiolite complex is on the southeast side of Kuskokwim Bay; otherwise only minor Triassic rock units are known. The most widespread rocks of the area are Jurassic and Early Cretaceous(?) volcanic and volcaniclastic rocks. The Kuskokwim Group flysch is restricted largely to the northeast part of the map area. It consists primarily of shelf and minor nearshore facies rocks. Primarily exposed in the lowlands west of the Ahklun Mountains, extensive latest Tertiary and Quaternary alkalic basalt flows and lesser pyroclastic rocks form much of the bedrock of the remaining area. On Saint Matthew Island, Cretaceous volcanic and pyroclastic rocks occur that are not found elsewhere within the map area. The Kuskokwim Group and older rocks, including on Saint Matthew Island, but not the Kanektok metamorphic complex, are intruded by widely dispersed Late Cretaceous and (or) Early Tertiary granitic rocks. Much of the lowland area is mantled by unconsolidated deposits that include glacial, alluvial and fluvial, marine, estuarine, and eolian deposits. These formed during several episodes of Quaternary glaciation.

Alaska↗

USGS2005

Offshore marine observation of Willow Ptarmigan, including water landings, Kuskokwim Bay, Alaska

We report an observation of Willow Ptarmigan ( Lagopus lagopus ) encountered 8 to 17 km from the nearest shoreline on Kuskokwim Bay, Alaska, on 30 August 2003. The ptarmigan were observed flying, landing on our research vessel, and landing and taking off from the water surface. We also report on one other observation of ptarmigan sitting on the water surface and other marine observations of ptarmigan from the North Pacific Pelagic Seabird Database. These observations provide evidence that Willow Ptarmigan are capable of dispersing across large bodies of water and landing and taking off from the water surface.

Alaska↗