Anadromous Fishes of California

Fry, Donald

The term anadromous means "up running" and is used to refer to fishes which spend part of their lives in the ocean but move into fresh water to spawn. Salmon are the best known anadromous fishes but there are many others, including striped bass, an dshad. Lesser known and less highly regarded species have the same habit. There are varying degrees of anadromy. The most extreme examples move from hundreds of miles at sea to hundreds of miles up a river, while some borderline species only move from brackish water a short distance into fresh water to spawn. We have included the latter if a large part of the population regularly moves out of brackish water to fresh water at spawning time. Many fishes are able to cope with extreme changes in the salinity of the water they inhabit. The technical terms for them is euryhaline and they may or may not be anadromous. The term comes from eury meaning broadly and haline meaning salty. Such forms often live in river estuaries where tidal action results in rapid changes in salt content. A moderately well known California native, which is euryhaline but not anadromous, is the starry flounder. It is normally marine, but has been known to move many miles into fresh water. Much better known, but not found in California, is the tarpon. Some sharks are euryhaline, including the dangerous bull shark, which moves between the Atlantic Ocean and Lake Nicaragua through many miles of moderately fast river. We are including euryhaline fishes only if we are reasonably sure they make a definite migration into fresh water to spawn. So little is known of the movements and of the spawning habits of some species that it is quite possible that we may have omitted some which will later be found to be truly anadromous. For example,the striped mullet, Mugil cephalus, is a euryhaline species which occurs worldwide in warm seas and is often seen in bays and estuaries from Los Angeles County south. It also enters the Colorado River. Using the scanty and conflicting evidence available it is possible to make a case for calling it anadromous, catadromous, or marine. I have not included it in this booklet.

Anadromous Fishes of California

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