Fishes

Arctic Grayling

(Photo: http://www.r7.fws.gov/nwr/arctic/fish.html)

General Information
The artic grayling is one of the most abundant freshwater fish in the oil field region, and is found on all the major river systems. (Inaru River, Meade River, Topagoruk River, Chipp River, Ikpikpuk River, Colville River, Kuparuk River, Sagavanirktok River, Shaviovik River, Canning River.)
 
“Grayling can be highly migratory, using different streams for spawning, juvenile rearing, summer feeding, and over winter survival. Or, in other areas, they can complete their entire life without leaving a short section of stream or lake. Their tolerance of low dissolved oxygen levels allows grayling to survive the long winters in areas where many other salmons would die. With the coming of spring, grayling begin an upstream migration to spawning grounds. Like salmon, grayling faithfully return every year to the same spawning and feeding areas. Grayling spawn for the first time at an age of 4 or 5 years and a length of about 11 to 12 inches.

About one month after spring breakup, adult grayling begin their post-spawning migration to summer feeding areas. Depending on where they have spawned, the distance traveled can be up to 100 miles. By the middle of summer, grayling will segregate within a stream according to age and maturity. The older adults will be found in the upper reaches of river and stream systems, the sub-adults in the middle, and the juveniles in the lower ends. Grayling fry hatch about three weeks after spawning, and they tend to occupy the quieter waters near where they were spawned. In the early fall, grayling again begin a leisurely downstream migration to reach over wintering areas.” (Rocky Holmes, 1994)

Critical Time Periods
During the summer the grayling use the glacial rivers as summer migration corridors and feast on hug numbers of drifting insects; they need this energy to survive the frozen and foodless months of winter.

During the winter streams are largely emptied of the artic grayling, and in fact of most fish. The lack of circulating oxygen in the frozen over streams makes it difficult for the fishes to breathe. The best time to build anything would be during winter.

Sensitivities/Proposal
“The distribution of artic grayling has expanded because of habitat alterations in the oil field region. Large deep gravel pits excavated to meet the needs for oil field construction material have filled with water after abandonment and formed large artificial lakes that provide abundant wintering habitat.
The populations of arctic grayling were reduced in the surrounding streams when pipelines and oil fields were first developed in Alaska. The culverts in the roads were of the wrong size, blocking upstream spawning migrations; this problem can be prevented by using smaller culverts and designing culverts based on grayling swimming performance.” (Rocky Holmes, 1994)

Dolly Varden

(Photo: http://www.r7.fws.gov/nwr/arctic/fish.html)

General Information
“Two basic forms of Dolly Varden occur in Alaska waters and both are common in all local coastal waters. The southern form ranges from lower Southeast Alaska to the tip of the Aleutian Chain, and the northern form is distributed on the north slope drainages of the Aleutian Range northward along Alaska’s coast to the Canada border. Anadromous and freshwater resident varieties of both forms exist with lake, river, and dwarf populations being found among the freshwater residents.

Young Dolly Vardens rear in streams before beginning their first migration to sea. During this rearing period, their growth is slow, a fact which may be attributed to their somewhat inactive habits. Young Dolly Varden often remain on the bottom, hidden from view under stones and logs, or in undercut areas along the stream bank, and appear to select most of their food from the stream bottom.

Most Dolly Varden migrate to sea in their third or fourth year, but some wait as long as their sixth year. At this time, they are about 5 inches long and are called smolt. This migration usually occurs in May or June, although significant but smaller numbers have been recorded migrating to sea in September and October. Once at sea, they begin a fascinating pattern of migration.

After their first seaward migration, Dolly Varden usually spend the rest of their lives wintering in and migrating to and from fresh water. Southern form Dolly Varden over winter in lakes, while most northern Dolly Varden over winter in rivers. Those hatched and reared in a lake system carry on annual feeding migrations to sea, returning to a lake or river each year for the winter. However, southern Dolly Varden originating from nonlake systems must seek a lake in which to winter. Recent research indicates that they find lakes by random searching, migrating from one stream system to another until they find one with a lake. Once a lake is found, these fish may also conduct annual seaward migration in the spring, sometimes entering other stream systems in their search for food.

At maturity, Dolly Varden return to spawn in the stream from which they originated. The fish possesses the ability to find their “home” stream without randomly searching, as was the case in their original search for a wintering area. Those of the southern form that survive the rigors of spawning return to the lake shortly thereafter, while northern form Dolly Varden usually overwinter in the river system in which they have spawned.” (Dennis Hubartt, 1994)

Critical Time Periods/ Sensitivities
“Dolly Varden spawn in streams, usually during the fall from mid-August to November. The female, depending on her size, may deposit from 600 to 6,000 eggs (2,500 to 10,000 in the northern form) in depressions, or redds, which she constructs in the streambed gravel by digging with her tail fin. The male usually takes no part in these nest building activities and spends most of his time fighting and chasing other males. When the female is ready to deposit her eggs, the male moves to her side and spawning begins. Sperm and eggs are released simultaneously into the redd.
The eggs develop slowly in the cold water temperatures usually present during the incubation period. Hatching of the eggs may occur in March, four to five months after fertilization. After hatching, the young Dolly Varden obtain food from their yolk sac and usually do not emerge from the gravel until this food source is used. Emergence usually occurs in April or May for the southern form and in June for the northern form.” (Dennis Hubartt, 1994)

Reference:
1.    Holmes, Rocky. (1994). http://www.adfg.state.ak.us/pubs/notebook/fish/grayling.php
2.    Hubartt, Dennis.  (1994). http://www.adfg.state.ak.us/pubs/notebook/fish/dolly_v.php