Prelab for Species Diversity,
Species Composition, and Size
Structure of Freshwater Fish
Communities
How does the presence of
predatory fish (piscivores) affect
the composition and size structure
of prey fish populations?
Help novice fisherpersons!
Look behind you before you
cast!
Watch your bobber, and set the hook
when it goes under water; try not to let
the fish swallow the hook!
Be sure but gentle
with the fish!
And be sure that
there is at least
one bucket of
water near you, to
put the fish in!
Be sure but gentle
with the fish!
Work quickly but
carefully, and have
keep careful records!
Have a second
person verify
everything
Make sure that you
know how to take
all measurements
properly!
Be very careful to
return all fish TO THE
SAME POND THAT
THEY WERE
CAPTURED IN – NO
MIXING!!!
Do NOT tag
unless you’ve
been properly
trained!
Have a second person verify all measurements, tag numbers, etc.
Bluegill Sunfish
(Lepomis macrochirus)
• large spot in posterior
part of posterior dorsal
fin;
• usually with vertical
barring (sometimes
faint);
• iridescence variable;
• may be melanistically
speckled;
• opercular flap or color
are NOTdiagnostic;
small ones may lack
the spot and resemble
tiny pumpkinseeds
Green Sunfish (Lepomis cyanellus)
• Large mouth and short dorsal spines compared to other sunfish;
• green color w/o obvious dark bars.
• Often with blue spots, esp. on operculum.
Green Sunfish
Lepomis cyanellus
Pumpkinseed Sunfish (Lepomis gibbosus)
• Strong spotting in posterior dorsal fin;
• May resemble bluegill if not in breeding condition or not old enough;
• Adults may have lots of orange on belly.
Green Sunfish x Pumpkinseed Hybrid
• Intermediate features, esp. mouth size, color, and dorsal spine length.
• Probably most of the individuals in pond E.
Largemouth Bass Micropterus salmoides
•
•
•
•
Angle of mouth extends beyond eye; longitudinal stripe on body;
Dorsal fins completely separated.
Smallmouth bass not likely; call any bass a largemouth unless sure.
Not a “true” Bass - same Family as the sunfishes: Centrarchidae
Largemouth Bass (Micropterus salmoides)
Channel Catfish, Ictalurus punctatus
Brown Bullhead, Ameiurus nebulosus
• Note the difference in
caudal (tail) fin shape
• Some Channel Catfish are
known to occur in pond A
• Some Brown Bullheads are
known to occur in pond E
Be sure to remove all worm guts from hooks,
replace lost weights and bobbers, etc. before
returning gear to rack