Field Guide to Freshwater Fish by Ken Schultz (z-lib.org)

In such instances, these fish are originally may be present on either side of the
saltwater in origin. They remain anadro- mouth of a fish that is primarily a bottom
mous when moved into purely fresh- feeder and is attracted by food odor.
water, although they use the lake as they Catfish, carp, and sturgeon are among
would the ocean. There are also species the species with such appendages.
of freshwater fish that are native to
freshwater and that migrate from lake to BASS
stream or river to spawn. These are not Many species of fish, in both freshwater
technically anadromous but adfluvial. and saltwater, are referred to as “bass.”
Some are truly bass and some are not,
Fish that originate in saltwater but but all have a physique and a profile that
have freshwater forms are often called are generally similar. Three of the most
“landlocked,” whether or not they have prominent freshwater sportfish with this
a clear path to and from the sea. Some- name include the largemouth bass and
times these fish are physically blocked the smallmouth bass, both of which are
from reaching the ocean. Fish in a reser- actually sunfish, and the peacock bass,
voir or a lake may be unable to leave. which is actually a cichlid.
Fish in some streams, like those in high-
mountain areas, have a clear passage- True bass are members of the Ser-
way to the sea but no means of ranidae family of sea bass,, which in fresh-
returning because of waterfalls. Coldwa- water includes the white bass and the
ter species may be effectively landlocked yellow bass, and in saltwater includes the
in the colder headwaters of a stream black sea bass, the striped bass, the giant
because temperatures are too high for sea bass, the kelp bass, and many other
them in the lowland parts of that stream species that do not carry the name “bass.”
or in the ocean in that area. Dolly
Varden, for example, are landlocked in BASS, BLACK
the southern tip of their range, but “Black bass” is a common name for all
anadromous forms are common farther species and subspecies of the genus
north. Micropterus, which belong to the Cen-
trarchidae family of sunfish. These
ANAL FIN include largemouth bass, smallmouth
The median, unpaired, ventrally located bass, redeye bass, spotted bass, Suwan-
fin that lies behind the anus, usually on nee bass, and Guadalupe bass. Black
the posterior half of the fish. bass are strictly freshwater species, and
they are more elongated and generally
AXILLARY PROCESS larger than their family relatives.
A fleshy flap, which is usually narrow and
extends to the rear, situated just above The term should not be confused
the pectoral or the pelvic fins on some with the various sea bass that are mem-
fish. bers of the Serranidae family of saltwater
fish, some of which have a physique sim-
BAITFISH ilar to that of species in the genus
A generic term used by anglers for any Micropterus.
fish species that are forage for predators,
although it often specifically pertains to BENTHIC
smaller fish; this term also references fish The bottom layer of the marine environ-
that are used in live bait angling. ment and the fish or the animals that live
on or near the bottom.
BARBEL
A whiskerlike feeler on the snouts of BONY FISH
some fish that contains taste buds and is Fish that have a bony skeleton and
used for touching and tasting food belong to the class Osteichthyes. Basi-
before ingesting it. One or more barbels cally, this includes all fish except sharks,
rays, skates, hagfish, and lampreys.

250 Glossary

BREAM COLDWATER FISH
Many species of both freshwater and A term for freshwater species whose
saltwater fish around the world are optimum environment contains cold
referred to as bream, particularly in Aus- and well-oxygenated water, usually
tralia, the United Kingdom, and the under 60°F, throughout the season;
United States. In the United States, trout, salmon, grayling, whitefish, and
“bream” (pronounced “brim”) is a collo- cisco are among this group. They inhabit
quial expression for various freshwater coldwater streams and generally infertile
panfish species, particularly sunfish and lakes; in lakes, their deep environs must
especially bluegills. have cold, well-oxygenated water
through the summer.
In Europe, the bream pursued by
anglers are members of the Cyprinidae COOLWATER FISH
family and are relatives of carp, barbel, An occasional term for freshwater species
and tench. These primarily small or mid- whose optimum environment is water of
size fish (less than 8 pounds) are bottom intermediate temperature, approxi-
feeders and are widely distributed. They mately from 60° to 70°F; northern pike,
are also a popular coarse (non-gamefish) muskellunge, yellow perch, walleye, and
species. The primary quarry is the bronze smallmouth bass are among this group.
bream, which is also known as the com- They inhabit cool to moderately warm
mon bream or the carp bream. rivers and lakes of moderate fertility,
often existing in waters that also accom-
In saltwater, various members of the modate species preferring colder and
Sparidae family are known as sea bream warmer temperatures.
and are related to porgies. Sea bream
occur in temperate and tropical waters CRUSTACEAN
worldwide. A group of freshwater and saltwater ani-
mals having no backbone, with jointed
CANINE TEETH legs and a hard shell made of chitin. In
Pointed canine teeth are found in some saltwater this group includes shrimp,
carnivorous fish; they are usually larger crabs, lobsters, and crayfish, all of which
than the surrounding teeth. may be used as bait when angling but
are not targeted by anglers or deliber-
CATADROMOUS ately sought with sporting equipment.
Fish that migrate from freshwater to salt- Freshwater crustaceans also include cray-
water in order to spawn. Fish that do the fish, as well as scuds, sowbugs, and
opposite are called anadromous and are shrimp.
more numerous. Freshwater eels are typ-
ical of catadromous fish; they are born at DEMERSAL
sea, migrate upstream to live and grow A term used for fish or animals that live
to adulthood, and then return to the sea on or near the seabed or the water bot-
to migrate to their spawning grounds. tom. Examples include flounder and
croaker. Demersal is often used synony-
CAUDAL FIN mously with groundfish.
The tail fin, or the fin at the rear of
DETRITUS
the fish. The fleshy section connecting Waste from decomposing organisms,
the caudal fin to the end of the body is which provides food for many other
called the caudal peduncle (see). organisms.

CAUDAL PEDUNCLE DIADROMOUS
The fleshy tail end of the body of a fish Fish that migrate between freshwater
between the anal and the caudal fins. and saltwater.
On some fish, the caudal peduncle is
rigid and provides a convenient “han-
dle” of sorts for holding the fish.

Glossary 251

DINOFLAGELLATE occur in new places through natural
Unicellular microscopic organisms, clas- means, but usually the agent is some
sified as plants or animals, depending on action of humans. That includes trans-
the presence of chlorophyll or the inges- portation of fish or larvae via the ballast
tion of food, respectively. Found in two of ocean freighters and the bait buckets
main groups, armored and naked, of small-boat anglers, passage of new
dinoflagellates have flagella (whiplike species via newly constructed canals, the
extensions) that provide locomotion, introduction of plants by using them in
and they move vertically in response to packing shellfish that are shipped
light. Many dinoflagellates are phospho- transcontinentally, the dumping of
rescent, and some greatly increase in aquarium plants and fish into local
number periodically, occasionally result- waterways, the experimental stocking of
ing in toxic red tides. Some dinoflagel- predator and prey species by scientists
late blooms are toxic to shellfish and can and nonscientists, and many other
cause gastroenteritis in the organisms means. Exotic species can be transported
that feed on them, including humans. by animals, vehicles, commercial goods,
As a component of phytoplankton produce, and even clothing.
(microscopic organisms that photosyn-
thesize), dinoflagellates are an important While some exotic introductions are
basis for marine life. ecologically harmless, many are very
harmful and have even caused the extinc-
DORSAL FIN tion of native species, especially those of
A median fin along the back, which is confined habitats. Freed from the preda-
supported by rays. There may be two or tors, the pathogens, and the competitors
more dorsal fins, in which case they are that have kept their numbers in check in
numbered, with the fin closest to the their native environs, species introduced
head called the first dorsal fin. into new habitats often overrun their new
home and crowd out native species. In
ENDANGERED SPECIES the presence of enough food and a
In the United States, a species is classified favorable environment, their numbers
as endangered if it is in danger of extinc- explode. Once established, exotics rarely
tion throughout all or a significant por- can be eliminated.
tion of its range. Elsewhere, a species is
classified as endangered if the factors FIN
causing its vulnerability or decline con- An organ on different parts of a fish’s
tinue to operate, as defined by the Inter- body that may be used for propulsion,
national Union for the Conservation of balance, and steering.
Nature and Natural Resources.
FINFISH
EXOTIC SPECIES An alternative collective term for all
Organisms introduced into habitats species of fish, used to separate true fish
where they are not native are called from crustaceans and mollusks, which
exotic species. They are often the agents are collectively termed shellfish. The
of severe worldwide, regional, and local term is rarely used in reference to fresh-
habitat alteration. Also referred to as water species but is commonly used to
nonindigenous, nonnative, alien, trans- refer to saltwater and anadromous fish,
plant, foreign, and introduced species, particularly by fisheries managers.
they can be the cause of biological diver-
sity loss and can greatly upset the bal- FINGERLING
ance of ecosystems. A young fish about 2 to 4 inches long.

Exotic species have been introduced FISHERY
around the world both intentionally and In a biological sense, all the activities
accidentally; occasionally, exotic species involved in catching a species of fish or a
group of species; the place where a

252 Glossary

species or a group of species is caught. In project over the throat opening and
common usage by the general public, strain water that is passed over the gills.
fishery also refers to fishing opportunity or These protect the gill filaments and, in
species availability in either a recreational some fish, are used to sieve out tiny food
or a commercial sense, as in “the fishery organisms. The number of gill rakers on
for coho salmon does not commence the first gill arch is sometimes used as an
until the annual migration run.” This term aid in identifying or separating species
is used interchangeably with fisheries. that closely resemble one another.

FISHKILL GRILSE
The die-off of fish, usually in numbers. A salmon, usually male, that returns to
Fishkills may occur as the result of freshwater rivers after 1 year at sea.
chemical pollution, especially from pesti- These are small fish, generally weighing
cides in agricultural runoff, but most from 2 to 4 pounds.
often happen as a result of insufficient
oxygen in the water. GROUNDFISH
A species or a group of fish that lives
A winter fishkill occurs when ice and most of its life on or near the seabed.
snow cut off the transfer of oxygen from The term may be used synonymously
the air to the water; the oxygen in the with demersal. Groundfish refers to
water gets used up, and fish die. This Atlantic cod, haddock, pollock, Ameri-
does not happen if there is enough oxy- can plaice, white hake, redfish, and vari-
gen in the water to last throughout the ous flounders.
winter until the ice and snow melt.
HYBRID
A summer fishkill usually occurs The offspring of two individuals of differ-
when inadequate amounts of oxygen ent species. The offspring of two individ-
exist in the water during extended peri- uals belonging to different subspecies of
ods of hot, calm, and cloudy days. Warm the same species are not hybrids.
summer water temperatures, high
demands for oxygen, and days with no Hybridization may occur in the wild
sunlight or wind to mix the surface or under artificial conditions. Some
water may lead to oxygen demands species that have been known to cross-
exceeding oxygen production. When breed naturally, although not frequently,
this happens, distressed fish may be seen include lake trout and brook trout
as they rise to the surface and gasp for (splake), northern pike and muskellunge
oxygen, and dead fish may be seen float- (tiger muskie), and walleye and sauger
ing on the surface. (saugeye). Hybrid fish have been culti-
vated in hatcheries by fisheries managers
FRESHWATER for stocking purposes; hybrid striped
Water with less than 0.5 gram per liter of bass (known as whiterock bass, wiper,
total dissolved mineral salts. and sunshine bass), which result from a
cross of pure-strain striped bass and
GILL white bass, have been extremely popular
A breathing organ with much-divided for stocking and are widely spread in
thin-walled filaments for extracting oxy- freshwater lakes and reservoirs. Most
gen from the water. In a living fish, the hybrid fish are sterile (although some,
gills are bright red feathery organs that like whiterock bass, are not), so the
are located on bony arches and are stocking of these fish is attractive
prominent when the gill covers of the because they can be controlled fairly
fish are lifted. well; if the initial stocking experiment
does not achieve the desired results, the
GILL RAKERS population of hybrids can be extin-
Toothlike extensions, located along the guished by discontinuing stocking.
anterior margin of the gill arch, that

Glossary 253

INSHORE surface or bottom (benthic or demersal,
The waters from the shallower part of respectively) dwellers.
the continental shelf toward shore. In
saltwater fishing parlance, inshore is a MIGRATION
loose and variable term referring to that A regular journey made by a particular
portion of the water from which land is species of fish, on an annual or a lifetime
visible or is nearly visible, usually on the basis, usually associated with propaga-
shoreward side of major currents or tion patterns but also associated with the
shelves, and is populated by nonpelagic seasonal availability of food. Most migra-
species. This term is seldom used by tions are mass movements and involve
freshwater lake anglers. travel over a particular route, usually at
the same time annually. Migration is not
LACUSTRINE to be confused with the relocation of fish
Having to do with, or living in, a lake. because of pollution, sedimentation,
storms, or the temporary relocation of
LANDLOCKED food sources. Anglers, for example, often
A term for anadromous fish that have refer to fish as making migrations from
adapted to a completely freshwater exis- deep water to shallow water to feed, an
tence, spending the greater portion of action that is really a localized move-
their lives in a lake and returning to natal ment. The periodic movement of fish in
rivers or streams to spawn. Any fish— a water body is not necessarily a migra-
usually salmon but also striped bass— tion, although the movement of a fish
with such behavior and without access species to and from breeding grounds
to saltwater is landlocked. (such as walleye in the spring moving
from a spawning river back to the main
LARVAE lake) is a migration.
The early life forms of a fish or other ani-
mal between the time of hatching and Migrations occur in various species
transforming to a juvenile. and in both freshwater and saltwater. All
freshwater fish that move from lake or
LATERAL LINE river environs to a tributary in order to
A series of sensory cells, usually running spawn will migrate to and from the
the length of both sides of the fish’s body, spawning grounds at or around the same
that performs an important function in time each year. All anadromous and
receiving low-frequency vibrations. catadromous fish undertake spawning
migrations, the former from saltwater to
LITTORAL freshwater and the latter from freshwater
Living in or related to nearshore waters; to saltwater, also around the same time
the intertidal zone of the marine envi- annually. Pelagic ocean species migrate
ronment that is exposed at low tide and from winter to summer grounds, both for
covered at high tide. spawning and for food procurement, also
around the same time annually.
LUNATE
Used to describe a caudal fin that is Migrations occur in north-south,
shaped like a crescent moon. south-north, offshore-inshore, and
inshore-offshore patterns, and in combi-
MARINE nations of these (some sea organisms
Pertaining to the sea and saltwater envi- migrate up and down in the water col-
rons, from the open oceans to the high- umn). Some fish migrations cover great
water mark and into estuaries; also used distances, even thousands of miles, and
to refer to seawater or saltwater. some are extremely short, perhaps just a
short distance up a river.
MIDWATER
In or near the middle layer of water. This MOLLUSK
term is generally used by biologists to A group of freshwater and saltwater ani-
describe the habitat of fish that are not mals with no skeleton and usually one or

254 Glossary

two hard shells made of calcium carbon- meaning physically on the land adjacent
ate. This group includes the oyster, the to water, but is even more specific than
clam, the mussel, the snail, the conch, nearshore. It is not the opposite of off-
the scallop, the squid, and the octopus. shore in common angling usage.
Mollusks may be used as bait when
angling, but they are not targeted by OPERCULUM
anglers or deliberately sought with The largest and uppermost bone that
sporting equipment. forms the gill cover of a fish.

NATIVE PALATINE TEETH
A species of fish that is endemic to a Teeth located on the palatine bones
region, a watershed, or a specific body inside the upper jawbone, usually
of water. A native species is distinguished behind the vomerine tooth patch.
from an introduced or exotic species,
which occurs outside its endemic range PANFISH
and has been placed there by unnatural This term is used widely by anglers and
means (usually deliberate but sometimes fisheries managers to collectively describe
accidental planting by humans). The a variety of small fish of several species.
term “native” is particularly applied in There is no individual species called a pan-
North America to endemic trout, espe- fish. The term is used almost universally in
cially brook trout. freshwater, seldom in saltwater; although
common to anglers, it may be unfamiliar
NEARSHORE or even confusing to nonanglers.
The shallow portion of inshore saltwaters
adjacent to the shoreline. In fishing parl- The term “panfish” often refers to
ance, inshore is a more common term fish that, when fried whole, can fit into a
than nearshore, and they are generally pan, but it is also frequently understood
interchangeable, although nearshore is to mean species that are not technically
more specific. classified as gamefish and that are usu-
ally abundant and as valued for their
NEST tasty flesh as for the enjoyment of catch-
A visible bed, often circular, made by ing them.
egg-laying fish on the bottom of a body
of water for spawning. Eggs are laid in Although panfish are commonly
the nest, and sometimes they are linked by these factors, the species that
guarded by one or more of the parents. fit under this umbrella are not all linked
biologically. Many “panfish” are mem-
NURSERY bers of the sunfish family, perch family,
The part of a fish’s or an animal’s habitat bass family, catfish family, and sucker
where the young grow up. family. These include, but are not lim-
ited to, such sunfish as green, longear,
OFFSHORE orangespotted, spotted, and redear vari-
Although this term practically signifies eties; plus bluegill, Sacramento perch,
the direction away from land, in fishing rock bass, warmouth bass, black crappie,
parlance it generally means that portion white crappie, yellow bass, white bass,
of the water from which land is not visi- yellow perch, and white perch. In some
ble, and to most saltwater anglers it per- areas, people include suckers, bullhead,
tains to deep-water areas, on the edge of pickerel, and even carp in this category.
ocean currents or shelves, where big-
game species, particularly billfish and PARR
tuna, are pursued. Small, young anadromous fish, particu-
larly salmon and trout, living in freshwa-
ONSHORE ter prior to migrating out to sea. During
Waters abutting a coastline. This word is this life stage, parr develop large vertical
also used synonymously with ashore, or oval rounded spots (sometimes called
bars) on the sides. Called parr marks,

Glossary 255

these help camouflage the fish and also POTAMADROMOUS
identify it; they will gradually disappear Fish that migrate within rivers or streams
as the fish becomes silvery, regardless of to spawn.
whether the fish goes to sea (some do
not). In the silvery phase, the fish is PREDATOR
known as a smolt. Migration to sea A species that feeds on other species.
occurs between 2 and 8 years. Most of the fish species that are pursued
by anglers are predators at or near the
PECTORAL FIN top of the food chain.
The fin usually found on each side of the
body, directly behind the gill opening. PREY
A species that is fed upon by other
PELAGIC FISH species.
Free-swimming fish that inhabit the
open sea and are independent of the REDD
seabed or the water bottom. A pit or a trough made by female salmon
and trout in the gravel bottom of rivers
PELVIC FIN or streams for spawning. Eggs are laid in
The pair of adjoining fins ventrally the redd, which is sometimes also called
located beneath the belly and in front of a nest.
the anus; also called ventral fins.
RIVERINE
PHARYNGEAL Of or living in a river or flowing water.
Bones in the throat of certain fish that
are used like teeth to crush food. These ROE
bones are hard and strong and will crush The eggs of a female fish; also a term for
such objects as clams, mussels, and a female fish with eggs.
snails. Carp have pharyngeal teeth,
which play an important role in their for- SALTWATER/SEAWATER
age habits. Commonly used terms for water with
many dissolved salts in or from the
PHYTOPLANKTON ocean, as well as in connected seas,
Microscopic suspended algae in the sur- bays, sounds, estuaries, marshes, and
face waters of seas and lakes, where the lower portion of tidal rivers.
there is enough light for photosynthesis
to occur. SCHOOL
A closely spaced collection of fish whose
PISCIVOROUS members swim in association with each
Fish eating. Most predatory fish, and other. Fish in a school are often of the
most of those considered sportfish, are same species and of similar size, but
piscivorous. species may intermingle and may vary in
size. Some species are noted for their
PLANKTON tendency to school, while other species
Passively floating or weakly swimming are more solitary.
organisms in a body of water. Planktonic
organisms may drift and float freely, SCHOOLING
range widely in size, and include the lar- (1) The behavioral grouping of fish, usu-
val stages of many fishes. Some are invis- ally of the same or related species, which
ible without magnification, and others move together as a unit and exhibit a
are visible to the unaided eye. specific geometrical relationship. Similar
to herding, schooling may be a natural
POD means of reducing predation and ensur-
A small, tight group of fish swimming ing the survival of some individuals.
together. Many species of fish school throughout
their lives, and young fish, as well as prey
species, are especially likely to school.

256 Glossary

Fish of different species seldom inter- portion of its range. Elsewhere, a species
mingle, although related species (such is classified as vulnerable rather than
as white bass and striped bass, for exam- threatened, according to the Interna-
ple) may do so. tional Union for the Conservation of
Nature and Natural Resources.
Schools are composed of many fish
of the same species moving in more or TUBERCLE
less harmonious patterns throughout the A small hard knob on the skin that
oceans. A very prevalent behavior, appears seasonally on some breeding
schooling is exhibited by almost 80 per- male fish.
cent of all fish species during some
phase of their life cycles. Many of the VERMICULATIONS
world’s commercial fishing industries Short, wavy, wormlike lines on the backs
rely on this behavior pattern to produce and sides of some fish.
their catch, especially for species like
cod, tuna, mackerel, and menhaden. VOMERINE TEETH
Teeth located on the vomer, a median
SEA-RUN bone in the front of the roof of the
Another term for anadromous, referring mouth of a fish.
to fish that move from the sea to fresh-
water to spawn. WARMWATER FISH
A term for freshwater species whose
SHOAL optimum environment contains warm
A school of fish, usually at the surface or water, usually over 70°F, and that can
in shallow water (a term used in Europe tolerate warm and even turbid or poorly
and sometimes in South America). oxygenated water during summer;
largemouth bass, various sunfish, crap-
SMOLT pie, bullhead, and catfish are among this
A young silvery salmon migrating from group. They primarily inhabit warm
freshwater to the sea. rivers and streams and very fertile lakes
and ponds, many of which are shallow.
THREATENED SPECIES
In the United States, a species is classified ZOOPLANKTON
as threatened if it is likely to become Minute suspended animals in the water
endangered within the foreseeable column of seas and lakes.
future throughout all or a significant

Glossary 257