Frequently Asked Questions
Is Craig Brook a state or federal hatchery?
Craig Brook National Fish Hatchery, along with Green Lake National Fish Hatchery in Ellsworth, Maine, is a national fish production facility funded through the U. S. Fish & Wildlife Service, an agency of the U.S. Department of the Interior. Operational funding for both hatcheries originates from Congressional allocations in Washington, D.C.
What species of fish does Craig Brook raise?
Craig Brook National Fish Hatchery raises one species of salmon--- sea-run Atlantic salmon, Salmo salar, The Atlantic salmon is an anadromous fish; they begin their lives as juveniles in fresh water environments and migrate to the ocean where they spend their adult lives. At four or five years old they return to their native river to spawn and unlike Pacific salmon, can repeat their ocean migration and spawn more than once.
Where do you stock sea-run Atlantic salmon?
Atlantic salmon fry (about an inch long and 6 months old) are stocked in the headwaters of their parents’ native river in good nursery habitat--- fast-flowing, cool, oxygen-rich water with a gravelly bottom. They will grow in that environment for two years before instinctively beginning their migration to the ocean at two years old.
What fish are stocked in Maine lakes?
The State of Maine operates nine hatcheries, raising and stocking lake trout, brook trout, brown trout, splake (a cross between lake and brook trout) and land-locked salmon (a close relative of sea-run salmon that do not migrate to the ocean).
How do sea-run salmon find their way home to their native river?
Research indicates that sea-run salmon imprint on the chemical “fingerprint”--the chemical smell--of their home river. They learn and remember the unique chemical makeup of the stream where life began years before.
During migration, how do fish know which way to go?
Biologists are uncertain just how fish are able to find their way in the open ocean. Atlantic salmon, for instance, migrate to Greenland and back— a distance of several thousand miles. Theories of how they accomplish these migrations, aside from their ability to locally recognize the smell of their home river, include the ability to detect the magnetic field of the earth, following ocean temperature gradients and currents, schooling behavior and food availability, among others.
What is an anadromous fish?
A catadromous fish?
An anadromous fish, born in fresh water, spends most of its life in the sea and returns to fresh water to spawn. Salmon, smelt, shad, striped bass, and sturgeon are common examples.
A catadromous fish does the opposite - it lives in fresh water and enters salt water to spawn. Most eels, for example, are catadromous.
How is the age of a fish determined?
Mainly by two methods: Growth "rings" on scales, and/or ringlike structures found in otoliths (small bones of the inner ear), are examined and counted. The rings correspond to seasonal changes in the environment and can be compared to the annual rings of tree trunks. A series of fine rings are laid down in scales for each year of life in summer, the rings grow faster and have relatively wide separations; in winter, slower growth is indicated by narrow separations between rings. Each pair of rings indicates one year. Because scale rings are sometimes influenced by other factors, scientists often use otoliths, whose ringlike structures also indicate years of life.
Is it true that salmon return to spawn in freshwater areas where they were born?
Almost always. Some straying has been documented, but it is minor. Most spawning salmon return to the precise stream of their birth, sometimes overcoming great distances and hazardous river conditions to reach home.
What is the difference between the Atlantic salmon and the Pacific salmon?
The Atlantic Salmon (Salmo salar) is actually one species within the genus Salmo. Pacific salmon are represented by seven different species, see question above, and belong to the genus Oncorhynchus. The seven Pacific salmon species have life histories that are extremely complex and vary widely within and between species. However, all the Pacific salmon die shortly after spawning. Atlantic salmon have a much less variable range of life history strategies across the species and have high post spawning mortality but are capable of surviving and spawning again.
How large do salmon get?
Weights of 100 pounds and slightly over have been reported from European countries for the Atlantic salmon; the record for the largest of the Pacific species, chinook, is 126 pounds for a fish caught on commercial gear in Alaskan waters.
How many eggs do salmon have?
Generally from 2,500 to 10,000 depending on species and size of fish. The chinook salmon generally produces the most and largest eggs.
What are salmon fed in a hatchery?
Vitamin-rich, high-protein diets made up of dried meals from coarse fish, animal meat excess, plant meal and bone meal, or meal from calcium-rich shells.
How many of the young salmon released from hatcheries come back as adults?
Releases of large fingerlings usually result in returns of one to five percent.
Why are fishladders constructed?
A fishladder, or fishway, often used in salmon streams, is constructed to provide for up-stream passage of fish over a dam or a natural barrier that might prevent or impede progress to spawning grounds.