Seasonal Distribution and Abundance of Sand Shrimp Crangon septemspinosa in the York River-Chesapeake Bay Estuary

Abstract

Sand shrimpCrangon septemspinosa were collected during monthly trawl surveys of the Chesapeake Bay and York River estuary from January 1971 to April 1972. Over 9000 shrimp were captured within wide ranges of temperature (0.5–24.1 C), salinity (10.3–31.1‰) and dissolved oxygen concentration (2.1–12.7 mg/liter). Relative abundance of shrimp in the channels varied seasonally. Maximum concentrations occurred in winter when bottom water temperatures were between 5 C and 11°C. The concentration of shrimp was reduced in spring when the temperature exceeded 15 C. Salinity limited the upstream penetration of the species. Occasionally shrimp were found in salinities as low as 10–12‰, but they were usually collected when salinities exceeded 16‰. Low levels of dissolved oxygen concentration (2–5 mg/liter) in summer coincided with reduced catches and absence of shrimp.