White shrimp (Litopenaeus setiferus) and brown shrimp (Farfantepenaeus aztecus) are two species commonly harvested in the Gulf and are the two dominant species landed in Alabama. A small amount of pink (Penaeus duorarum) and royal red shrimp (Pleoticus robustus) are also landed in the state. Generally, shrimp are resilient to fishing pressure, and their life history makes them more like an “annual crop” (Gulf FINFO). They are short lived, grow rapidly, are highly fecund, and migrate through several environments (GMFMC Shrimp Fishery Management Plan (FMP)). Shrimp spawn within their first year and typically die before reaching two years. The life cycles of white and brown shrimp are very similar, but with temporal and spatial variations at which life stages reach their maximum abundance (GMFMC Shrimp FMP). During the larval stage, shrimp feed on phytoplankton and zooplankton. Postlarval shrimp migrate into estuaries where they become bottom feeders and typically feed on epiphytes, detritus, and algae. Juveniles and adults become more predatory and often prey on polychaetes, amphipods, nemotodes, and chironomid larvae, but also continue to feed on detritus and algae. Shrimps are preyed upon by a wide variety of species. Primary finfish predators include black drum (Pogonias cromis), redfish (Sciaenops ocellatus), speckled trout (Cynoscion nebulosus), southern flounder (Paralichthys sp.), Atlantic croaker (Micropogonias undulates), and several species of catfish.
White Shrimp
White shrimp range from the Atlantic Coast of New York down the coast of Florida and across the Gulf from The Ochlochonee River to Campeche, Mexico (FishWatch-white shrimp). White shrimp spawn offshore in waters 23 to 102 feet deep, and spawning activity is most likely correlated with a rapid change in bottom temperature (Turner and Brody 1983). A single female white shrimp releases up to one million eggs in a spawn, and spawning usually occurs spring through fall. Multiple spawnings in one season is possible. The larval phase for white shrimp lasts about 10 days, depending on habitat conditions. White shrimp go through several larval and postlarval stages as plankton offshore. In the second postlarval stage, they move into estuaries and become benthic. They prefer muddy substrates in which to burrow (Muncy 1984). Within one year, they are sexually mature, and growth rates are dependent on water temperature (Muncy 1984).
Brown Shrimp
Brown shrimp are found in the western North Atlantic from Martha’s Vineyard, Massachusetts, to the Florida Keys and along the Gulf Coast to northwestern Yucatan in Mexico (FishWatch – brown shrimp). Brown shrimp typically spawn offshore in waters 60 to 358 feet (Turner and Brody 1983). There are two peak spawning times; September to November and April to May. Fertilized eggs hatch within 24 hours of release into the water column. It takes ten to 25 days for newly hatched shrimp to reach postlarval stage (Lassuy 1983). Postlarval brown shrimp may overwinter and burrow until temperatures favor recruitment to estuaries (Lassuy 1983). They move into estuaries at night on incoming tides and move to shallow soft-bottom areas for nursery grounds. Young brown shrimp stay in the shallow areas near marshes, mangroves, or seagrass beds. During May through August, once they reach a certain size, brown shrimp emigrate to deeper waters. Brown shrimp are omnivorous, and the estuary areas provide shelter and food for shrimp as they grow and mature.
Pink Shrimp
Pink shrimp are found in the western North Atlantic from southern Chesapeake Bay to the Florida Keys, and across the Gulf of Mexico to the Yucatan (FishWatch – Pink Shrimp). The largest commercial harvest of pink shrimp in the Gulf occurs off the Florida coast. They are a common prey species for many commercially and recreationally important species. Spawning occurs in waters 12 to 156 feet deep and occurs year round on the Tortugas Shelf (Bielsa et al. 1983). There is some seasonality to spawning as larvae tend to be more abundant during spring, summer, and fall (Bielsa et al. 1983 ). After hatching, larvae are transported to estuarine nursery areas via currents, where they will remain for two to six months as they mature (Bielsa et al. 1983). Juveniles forage along to bottom in shallow-water grass beds, primarily at night. When they reach approximately 3.5 inches, they emigrate from nursery areas to offshore waters. Pink shrimp do share habitats with white and brown shrimp, but prefer different salinities, temperatures, and substrates. Pink shrimp generally prefer higher salinities and coarser substrates than brown shrimp (Bielsa et al. 1983).
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