bright silvery blue on back, silvery sides and dusky white belly; deep oblong body that is laterally compressed; maximum size range in Iowa is about 9-14 inches
Shad make great bait for catching channel catfish!
The gizzard shad is common to abundant in many Iowa waters and has been collected statewide except for a few northwest locations. The fish has been collected in all of the major river systems, large reservoirs, and many of the man-made lakes.
Gizzard shad exhibit the typical herring body shape with a deep, oblong body that is strongly compressed laterally. Color ranges from bright silvery blue on the back, silvery sides and a dusky white on the belly. A dark shoulder spot is common on younger fish but may be absent from adults. The front of the head is rounded with a sub-terminal mouth. Teeth are absent. There are about 190 rakers on the lower limb of the first gill arch. The eyes have adipose eyelids with vertical slits. Body scales are cycloid with no lateral line present. The ventral scales are keeled. Dorsal fin rays number 10 to 12 with the last ray elongated into a thin whip-like filament. This fin is inserted slightly behind the pelvic fin. An auxiliary process is present at the base of the pelvic fin. The anal fin has 27 to 34 rays, and the caudal fin is deeply forked.
Gizzard shad prefer sluggish rivers and soft-bottomed lakes. The fish is synonymous with mud. It is found most commonly in open water near the surface. The fish are random, nocturnal group spawners in shallow bays or coves with no care given to the young. Eggs are released near the surface of the water from late April or early May to early August at 50 to 70 degrees F. The eggs are adhesive and sink. The females are prolific, producing up to 400,000 eggs that are about .03 inch in diameter.
The species is an omnivorous filter feeder taking both phytoplankton and zooplankton, which are then ground in the gizzard-like section of the gut. Some bottom material is often ingested while feeding; hence, the name mud shad or mud feeder. Shad are intermediate hosts for several species of the glochidiad stages of mussels and in that respect have economic importance in the perpetuation of freshwater mussels with commercial value.
Shad commonly reach 4 inches in length during the first year of life. The maximum size range in Iowa is about 9 to 14 inches.
Gizzard shad have little value as a food-fish and are seldom taken by hook-and-line. Its flesh, and particularly the gizzard-like stomach, are occasionally fermented for use as catfish bait. Dense shad populations provide considerable forage as young for other predatory fishes, and their schooling behavior during the first year make them easy prey for larger fish. Some controversy surrounds this forage value, however, as shad quickly outgrow the vulnerable forage size and rapidly assume pest levels in some closed watersheds or when predator populations are insufficient to control their numbers. Evidence is quite strong that shad compete with young bluegill for food items, and when populations reach very dense levels, bluegill survival is inevitably lowered. At that time, eradication of the entire fish population and game fish species restocking, particularly in small lakes seems to be the only alternative in restoring acceptable fishing. Massive die-offs of young and yearling shad are commonly reported after spring ice-out as a result of their susceptibility to fluctuating water temperatures.