Hickory Shad

Spawning of Gizzard Shad is random and occurs from mid-May to mid-June near the surface of water in low-gradient areas. Adult females and males gather in large aggregations and eject sperm and eggs into the water. Eggs sink to the bottom and adhere to any object or surface they come in contact with. The average female produces approximately 300,000 eggs per year, eggs will hatch in 2-3 days. Young fish travel in compact schools after hatching and will typically disperse by fall, schooling is rare at age one. Reproductive maturity is normally reached at ages 2 or 3. Lifespan depends on the environment a population is found in and shorter life spans are associated with rapid growth in the first year of life. Longer life spans are typical in the northern parts of its range and individuals live to 5-7 years and have been reported living up to 10-11 years (Etnier and Starnes 1993; Williamson and Nelson 1985; Miller 1960).

Gizzard Shad are planktivores, straining minute organic particles with their gill rakers into their pharyngeal organ which is thought to concentrate and process food for swallowing. They also feed heavily on detritus found on bottom sediments, individuals consume an average of 13% of their wet weight biomass in dry sediment each day. Their diet remains largely similar at different sizes and has been found to contain algae, phytoplankton, zooplankton, and plant debris. Because Gizzard Shad are primary consumers, extremely large populations can be supported. Fry feed primarily on copepods and cladocerans, whereas adults consume large amounts of phytoplankton and zooplankton. Gizzard Shad is part of the diet of at least 17 game fishes some of which include Walleyes, White Bass, Largemouth Bass, White Crappie, Gars, Black Crappie, Sauger, Yellow Trout, Catfish, the Freshwater Drum, and Lake Trout. The Striped Bass and Muskellunge have been introduced into reservoirs to prey on Gizzard Shad.  Waterfowl also prey on the species. Winter die-offs cause individuals to float to the surface where they are consumed by crows, turkey vultures, bald eagles, and waterfowl. Gizzard Shad grow rapidly in shallow, fertile impediments with abundant food and long growing seasons. This rapid growth frequently causes individuals to become too large for most predators, reaching 10-18 cm within the first year (Etnier and Starnes 1993; Williamson and Nelson 1985; Miller 1960; Mundhal 1990).

Dorosoma cepedianum has a moderate beneficial impact in the Great Lakes.

Gizzard Shad is an important forage fish for some game fishes and has been said to be “the most efficient biologically of all the forage fishes” for its direct use of phytoplankton, high reproductive capacity and abundance, general freedom from parasites and rapid growth. Its primary drawbacks are mortality in spring and fall and sensitivity to handling (Miller 1960). In 1999, the commercial value of Gizzard Shad fisheries in the Great Lakes was  $7,493 (R. Kinnunen pers. comm. 2018).

Gizzard Shad is absent from the New York baitfish green list.

Note: Check federal, state, and local regulations for the most up-to-date information.

Control

Biological

Predators of Gizzard Shadcan be stocked to control population, examples of predators include Largemouth Bass, Walleye, and Northern Pike (Miller 1960).

Physical

Seining has been used to remove Gizzard Shad in areas where the species has reached nuisance levels  (Miller 1960). Although, bycatch of non-target species can be high with this method (Catalano et al. 2007).

Chemical

Gizzard Shad are extremely sensitive to rotenone. Treatments of 0.1 mg/L can be used to selectively kill this species. Complete draining or reclamation with rotenone is often needed before restocking (Wynne 2013).

Note: Check state/provincial and local regulations for the most up-to-date information regarding permits for control methods. Follow all label instructions.