Bay shrimp are small shrimp which inhabit estuaries along the Western coast of North America from Alaska to San Diego. These shrimp are not commercially important, except in the San Francisco Bay, where they are caught primarily for use as bait, although some people also consume them. While not generally commercially important, they are of interest as an indicator species, thanks to their sensitivity to overfishing, temperature changes, chemical pollution, and fluctuations in salinity.

The bay shrimp is formally known as Crangon franciscorum. These shrimp have slightly flattened dark gray to yellowish gray bodies, and pink eyes. They go by a variety of alternate names, including California chrimp, black shrimp, sand shrimp, common shrimp, and grass shrimp, and they prefer the mildly saline waters of bays and estuaries, not the open ocean. In the San Francisco Bay, bay shrimp are the most common shrimp species.

When bay shrimp spawn, they congregate in areas of higher salinity. Salinity levels appear to have an impact on the development of the young shrimp, so biologists may track the movements and health of bay shrimp populations to see how salinity changes are affecting them. Because many estuaries are at risk of heavy pollution, bay shrimp are also a very useful indicator species, as they can provide early warnings about a pollution problem.

In bays where fishing and other human activities take place, bay shrimp can also be used to monitor the impact of human activity on the environment. Bay shrimp are a common bycatch in nets, so a drastic decline in their population can suggest unsustainable fishing practices. These crustaceans are also sensitive to construction projects, which may drive away sources of food or alter the composition of the water.

In regions where bay shrimp are treated as a commercial commodity, the vast majority are caught for use as bait by fishermen and commercial fisheries. However, bay shrimp are also perfectly edible, and some people on the West Coast consider them to be a delicacy, perhaps because they are not as commonly available on the open market as other shrimp species.