Gizzard shad grow quickly and attain a much larger size
than threadfin.
Some adults can reach 20 inches long and weigh 2-pounds.
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The gizzard shad has the typical herring family shape, but with a distinctive dorsal fin. Its short, soft-rayed dorsal fin is located at the center of its back. It has a long, trailing filament as the rear ray, longer than any of the other rays. The gizzard shad’s back is silvery blue-green to gray. The sides are silvery or reflect blue, green, brassy or reddish tints. There is no lateral line. The tail is deeply forked, and the lower jaw is slightly shorter than the upper jaw. The snout is blunt. The mouth is small, and there is a deep notch in the center of the upper jaw. The gizzard shad’s eye is large. There is a big, purplish-blue spot near the edge of the upper gill in young gizzard shad and small adults. This spot is faint or disappears completely in larger, older fish. The fins are dusky and there are the usual herring sawtooth-edged belly scales. Gizzard shad grow rapidly and can reach a maximum size of about 20 inches.
Gizzard shad are filter-feeders, straining small animal organisms and plants from bottom mud and organic deposits. The adults have more than 400, fine gill rakers that can catch minute plankton. Gizzard Shad have an unusual digestion process for fish. The vegetable material they eat is ground in a gizzard like stomach.
Gizzard Shad rapid growth means that largemouth and smallmouth bass are able to eat them for only a short time each spring. The Gizzard Shad spends most of its time in large schools cruising for food.
Habitat:
The gizzard shad is a schooling fish found in lakes and
impoundments. It also lives in the backwaters of sluggish rivers and the
deep, slow pools of smaller streams. Gizzard shad become more abundant as a
lake eutrophies–that is, as it gains fertility through natural aging or
added pollutants.
Generally found in fresh water, gizzard shad can also live in the brackish
water of tidal zones and estuaries. Unlike many other herrings, gizzard shad
are nonmigratory and stay near their home areas. They are often found over a
mucky bottom, which they filter when feeding.
Life history:
The
gizzard shad spawns
in spring, May to June, when water temperatures reach the mid-60s to
mid-70s.
They have a special stomach which grinds up plants and small animals it finds in muddy bottoms of lakes and streams.
Striped bass are the dominant predator for the large Gizzards and keep
them under control so that young Largemouth bass and Large shad don't have
to compete for the same limited planktonic food allowing the fingerling black bass to grow quicker.
Gizzard shad move upstream into shallower waters to spawn,
but otherwise
show no obvious spawning migration pattern.
Young gizzard shad School in quiet surface waters, bigger adults near
bottom. Six week spawning period. Most spawn at age 2.
Buoyant larvae become plankton. Life span 4-6 years, few live beyond age 3.
Spawning Habits of Gizzard Shad
GIZZARD SHAD
Dorosoma Cepedianum
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Coloration:
Back silvery blue, somewhat iridescent; sides silvery above, whitish below; abdomen white.
Fins darkened.
Dark purplish spot about the size of the eye present immediately behind the upper end of the gill opening.
Spot becomes obsolete and disappears with age.
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Mouth:
Small sub-terminal, slightly overhung by the rounded snout.
Centrally notched upper jaw protrudes slightly beyond lower jaw.
Upper jaw reaching below the front margin of the eye.
Gill rakers long, slender
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Body:
Deep strongly compressed laterally.
Average length 8.5 -13.5 in.
Scales large, thin, rounded and smooth-edged , Falling off or shed at a specific season or stage of growth.
Lateral line lacking.
Median lateral series of scales 61 (52-70).
Ridge of sawlike scales close to the abdomen.
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Gizzard Shad differ from Threadfin Shad by:
lower jaw shorter than upper jaw;
a much shorter dorsal fin filament;
absence of black pigment on the chin and floor of mouth; more than 17 midventral scutes in the prepelvic series;
more scales in the lateral series; more anal fin rays.
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Biology and Spawning:
Will school up as juveniles in quiet surface waters, adults near bottom.
Spawn at night in spring, in shallows.
Eggs randomly scattered adhere to plants, rocks or firm substrate.
Preferred Temps 66 -72 degrees F. Will start at 50 degrees
Six week spawning period.
Most spawn at age 2.
producing 22,000 to 400,000 eggs .
Incubation 2-4 days.
Buoyant larvae become plankton.
Life span 4-6 years, few live beyond age 3.
Adult die-offs common.
Adults bottom filter feeding from areas along shorelines.
Open water fish have mostly phytoplankton and sand for digestion.
Juveniles planktivorous.
Preferred temp is 72 -76 degrees F.
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