Estimates of Hard Clam Abundance from Hydraulic Escalator Samples by the Leslie Method

Northern Quahog (=hard Clam) Mercenaria Mercenaria Age at Length Relationships and Growth Patterns in the York River, Virginia 1954 to 1970

“…Historically, quahogs were a benthic dominant species in sandy mud habitats with salinities less than 10 ppt (Roegner & Mann 1991). Although oyster (Crassostrea virginica) population levels in the lower Chesapeake Bay were decimated during the period 1950-1972 by a combination of disease, abnormal environmental conditions, and fishing pressure (Andrews 1996, Burreson & Calvo 1996, northern quahog populations remained relatively stable in terms of abundance and demographics through the early 1970s (Loesch & Haven 1973a, 1973b. While northern quahog populations in the lower Chesapeake Bay currently support commercial fishing activity, population density levels in 2001 to 2002 (Mann et al 2005) are an order of magnitude lower than those observed by Haven et al (1973) and Loesch & Haven (1973b).…”

“…Although oyster (Crassostrea virginica) population levels in the lower Chesapeake Bay were decimated during the period 1950-1972 by a combination of disease, abnormal environmental conditions, and fishing pressure (Andrews 1996, Burreson & Calvo 1996, northern quahog populations remained relatively stable in terms of abundance and demographics through the early 1970s (Loesch & Haven 1973a, 1973b. While northern quahog populations in the lower Chesapeake Bay currently support commercial fishing activity, population density levels in 2001 to 2002 (Mann et al 2005) are an order of magnitude lower than those observed by Haven et al (1973) and Loesch & Haven (1973b). Modern Chesapeake Bay quahog populations and habitat are threatened by continued watershed degradation, shoreline development, dredging activity for shipping channels and dock access, as well as increased fishing pressure concurrent with the decline of the oyster industry.…”