Yukon River Drainage Research Articles

Jumbo spotted form of least cisco Coregonus sardinella in lakes of southern Yukon Territory

Four lakes on the upper Yukon River drainage contain a strikingly spotted jumbo form of least cisco, with fork lengths up to 452 mm, larger than all previously known lacustrine or anadromous forms. The jumbo fish, with high gill raker counts (48–52), are probably nonmigratory. They may in each lake represent parallel responses to high dissolved solids, little competition, and unusually favourable conditions for growth. Available material is insufficient to establish whether small specimens in these lakes are young or slow-growing individuals of the jumbo spotted form, or whether the lakes contain two sympatric populations.

Life History Notes for a Population of Slimy Sculpin (Cottus cognatus) in an Alaskan Arctic Stream

The distribution of a slow-growing population of slimy sculpin (Cottus cognatus) extends farther than most fishes into the headwaters of the Chandalar River, Yukon River drainage. The maximum observed age was 7 by which time the fish averaged only 101 mm in length. Most sculpin matured at age 4. The spawning season appeared to be shortly after spring breakup (late May). Fecundity averaged 206 eggs (range 59–339 eggs). The fish fed almost exclusively on stream benthos, chironomid larvae being the most common food item.

Ferns and Fern Allies of the Central Yukon Valley

The following list of ferns and fern allies has been compiled from my own collections of various summers in the vast, mostly unglaciated region of mountains, valleys, rivers, and creeks that form a part of the Yukon River drainage system, and from specimens of other collectors preserved in the Gray Herbarium. These I have supplemented by all published lists of collections known to the writer. The most complete the catalogue of specimens in Hulten's monumental Flora of Alaska and Yukon. l To this work I am much in debt, and also to Anderson's Flora of Alaska and Adjacent Parts of Canada,2 especially for being enabled thereby to include two species in our district which I could not have done otherwise. For convenience I have followed Hulten's divisions and boundaries, according to which the Central Yukon River District is taken to include the basin of the Yukon River from the mouth of Stewart R. to the mouth of Koyukuk R., as well as the basins of the large tributaries of the Tanana R. and Porcupine R. The upper parts of the tributaries of the Tanana R. from the south are regarded as belonging to the Alaska Range District