A

alevin

Young salmon that have hatched but still have a large yolk that must be absorbed, during which they stay protected in gravel; they may live entirely on yolk or may feed (may also be called "sac-fry").

anadromous

(Greek for "running upward") Fish that are born in fresh water, move to salt water to feed, and return to fresh water to spawn.

C

catadromous

Fish that are born in salt water, move to fresh water to feed, and return to salt water to spawn.

D

diadromous

Fish that can live in fresh and salt water, at different times in their lives.

E

estuary

A site where fresh water and salt water meet.

F

fish ladder

Water-filled staircase that allows migrating fish to swim upstream around a dam.

fry

Next life stage of salmon after alevin, and before smolt (upon reaching 1.25 inches in length, they are sometimes called "fingerlings") (see also "parr").

G

gill

Respiratory organ of fish.

H

homing

The behavior of returning to the stream where you were hatched.

I

iteroparous

Spawn more than once.

O

opercula

The gill covers of a fish.

P

parr

Stripes on the sides of salmon fry; sometimes used instead of "fry" to refer to juvenile salmon.

R

redd

Series of nests dug in gravel by one female salmon.

S

semelparous

Spawn only once during their lifetime.

smolt

Salmon of a certain size, generally 4-7 inches, that begin seaward migration and smoltification.

smoltification

Process of morphological and physiological adjustment that young salmon of a certain size undergo to live in salt water.

spawning

The act of laying eggs.