Fishes
Artic Grayling
Arctic Grayling
(Photo: http://www.r7.fws.gov/nwr/arctic/fish.html)
General Information
The artic grayling 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
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