The original award-winning NEFSC FishFAQ, created in 1993, has been archived.
For current information, please see our new FAQ.

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 - lives in fresh water and enters salt water to spawn. Most of the eels are catadromous.

Why do scientists classify fish?

Since common or colloquial names of fish vary from place to place (menhaden, for example, are known by at least three different names, and striped bass are called "stripers" in New England and "rockfish" in Chesapeake Bay),
investigators would have no way of differentiating among species without a uniform naming system. The system used to name the 20,000 odd fishes known to science is called "the binomial system of nomenclature." It usually consists of a scientific name in two parts, the generic and specific names, or three parts if subspecies have been described.

Striped Bass

The words of the names are latinized regardless of the language or alphabet of the study and are frequently descriptive of a significant feature of the organism.

The generic name generally applies to several species showing basic characteristics while a specific (species) name is based on a few characteristics applying to one species, separate and distinct from all others. (Example: The generic name Morone applies to white perch, white bass, and striped bass; the species names for those three fishes are Morone americanus, M. chrysops, and M. saxatilis.)

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.

otolith     fish scale

Otolith (L) - Scale (R)

Here is how we age fish at NEFSC

How long do fish live?

A few weeks or months (some of the small reef fishes) to 50 years or more (sturgeons) Longevity information is still sparse, but scientists have learned that species live 10 to 20 years in temperate waters.

sturgeon Sturgeon

Do some fish give birth to living young?

Yes, many do. These are called viviparous fishes. The sea perches of the Pacific coast, for example, give birth to living young of considerable size, sometimes one-fifth the size of the mother. Several kind of sharks produce living young

previous buttonreturn to faq buttonnext button
NMFS Search
Link Disclaimer
Privacy Policy
(File Modified Aug. 25 2017)