Ken Schultz's Field Guide to Saltwater Fish - Macaw Pets store

(microscopic organisms that photosynthesize),
dinoflagellates are an important
basis for marine life.
DORSAL FIN
A median fin along the back, which is
supported by rays. There may be two or
more dorsal fins, in which case they are
numbered, with the fin closest to the
head called the first dorsal fin.
ENDANGERED SPECIES
In the United States, a species is classified
as endangered if it is in danger of extinction
throughout all or a significant portion
of its range. Elsewhere, a species is
classified as endangered if the factors
causing its vulnerability or decline continue
to operate, as defined by the International
Union for the Conservation of
Nature and Natural Resources.
EXOTIC SPECIES
Organisms introduced into habitats
where they are not native are called
exotic species. They are often the agents
of severe worldwide, regional, and local
habitat alteration. Also referred to as
nonindigenous, nonnative, alien, transplant,
foreign, and introduced species,
they can be the cause of biological diversity
loss and can greatly upset the balance
of ecosystems.
Exotic species have been introduced
around the world both intentionally and
accidentally; occasionally, exotic species
occur in new places through natural
means, but usually the agent is some
action of humans. That includes transportation
of fish or larvae via the ballast
of ocean freighters and the bait buckets
of small-boat anglers, passage of new
species via newly constructed canals, the
introduction of plants by using them in
packing shellfish that are shipped
transcontinentally, the dumping of
aquarium plants and fish into local
waterways, the experimental stocking of
predator and prey species by scientists
and nonscientists, and many other
means. Exotic species can be transported
by animals, vehicles, commercial goods,
produce, and even clothing.
While some exotic introductions are
ecologically harmless, many are very
harmful and have even caused the extinction
of native species, especially those of
confined habitats. Freed from the predators,
the pathogens, and the competitors
that have kept their numbers in check in
their native environs, species introduced
into new habitats often overrun their new
home and crowd out native species. In
the presence of enough food and a
favorable environment, their numbers
explode. Once established, exotics rarely
can be eliminated.
FIN
An organ on different parts of a fish’s
body that may be used for propulsion,
balance, and steering.
FINFISH
An alternative collective term for all
species of fish, used to separate true fish
from crustaceans and mollusks, which
are collectively termed shellfish. The
term is rarely used in reference to freshwater
species but is commonly used to
refer to saltwater and anadromous fish,
particularly by fisheries managers.
FINGERLING
A young fish about 2 to 4 inches long.
FISHERY
In a biological sense, all the activities
involved in catching a species of fish or a
group of species; the place where a
species or a group of species is caught. In
common usage by the general public,
fishery also refers to fishing opportunity or
species availability in either a recreational
or a commercial sense, as in “the fishery
for coho salmon does not commence
until the annual migration run.” This term
is used interchangeably with fisheries.
FISHKILL
The die-off of fish, usually in numbers.
Fishkills may occur as the result of
chemical pollution, especially from pesticides
in agricultural runoff, but most
often happen as a result of insufficient
oxygen in the water.
Glossary 269