Maryland striped bass: Recruitment declining below replacement
A mathematical technique was developed to examine interrelationships among first‐year survival rates, adult fecundity, and adult survival of striped bass Morone saxatilis based on indices of year‐class strength. Application of this technique to striped bass in Maryland waters of the Chesapeake Bay provided evidence for reduced survival in the life cycle. If adult fecundity and survival have remained constant, first‐year survival declined significantly from 1969 to 1983, and averaged less than that needed for replacement for the last 10 years. Treatment of the individual spawning grounds separately indicated that the downward trend in survival for the pooled data was the result of declines in the upper bay and, to a lesser extent, in the Choptank River. Alternatively, if first‐year survival and adult fecundity were assumed to have remained constant, an annual decline of about 1.9% in adult survival would have been required to produce the observed trend in the pooled year‐class data. This would be consistent with increased fishing mortality and implies declining recruitment because of declining stock size. Continuing declines in first‐year or adult survival would eliminate the Maryland striped bass stock and the fishery it supports. Conversely, an increase in adult survival could offset the effect of the unknown factor or factors responsible for the apparent decline in first‐year survival.