DID YOU KNOW? The bay shrimp is the most common shrimp in most Pacific coast estuaries.
SCIENTIFIC NAME: Crangon franciscorum.
COMMON NAMES: Sand shrimp, grass shrimp, common shrimp, black shrimp, California shrimp, and black tailed shrimp.
DESCRIPTION: Stout, depressed body with a thin shell and smooth surface. Color tends to be a dark and light yellowish gray with salmon-colored eyes.
LIFECYCLE: The bay shrimp is sensitive to temperature and salinity changes during its lifecycle. During reproductive periods which vary greatly with geographical location, bay shrimp move toward more saline areas of the estuaries to spawn. In their early life-stages, juveniles utilize the upper parts of estuaries as nurseries, preferring the lower salinity there. As it grows and matures, the bay shrimp moves to more saline areas of the estuary and offshore. Water temperature is especially critical to the bay shrimp as a regulator of its life functions. Females usually produce 2,000 to 8,000 eggs, and store the male's sperm inside their bodies. Egg fertilization is done when the female extrudes eggs into her 'brood pouch'; she carries with her for approximately 8 to 12 weeks until they hatch. Maturity is commonly reached in 1 to 1.5 years.
RANGE: Common in most Pacific coast estuaries from San Francisco to Puget Sound, although the bay shrimp is also found south of San Francisco to San Diego. The bay shrimp is abundant in bays with mud and sandy bottoms and offshore in deeper waters.
HABITAT AND ECOLOGY: As the most dominant shrimp in Pacific coast estuaries, the bay shrimp is an important part of the food chain. It is the predominant food of many sport and recreational fish, including striped bass, sturgeon, Dungeness crab and Pacific tom cod. The bay shrimp itself commonly feeds on bottom dwelling animals (epibenthic fauna), amphipods and plant material. In search of food, bay shrimp agitate the bottom and cycle nutrients into coastal systems. It is a short lived species that is sensitive to pollution in estuaries. Males commonly only live until their first spawn, 1 to 1.5 years, while females can live until their second spawn, approximately 2 to 2.5 years.
Because of the bay shrimp's preference for different levels of salinity during its lifecycle, freshwater inflow into estuaries strongly influences distribution, survival, and abundance. Maintaining the flow of freshwater into estuaries is critical because of its impact on water temperature, salinity, and landward currents. Because estuaries play a critical role in the bay shrimp's life history, alteration of this habitat directly affects its populations.
ECONOMIC VALUE: Fished commercially since the 1800's, the bay shrimp is presently fished commercially only in San Francisco Bay with landings ranging from 2 - 25 tons per year. It is fished mainly for bait. Some is used for human consumption though shelling and marketing bay shrimp is not economically lucrative.