Use of Egg Presence–Absence to Derive Probability-Based Management Criteria for Upper Chesapeake Bay Striped Bass

Abstract I used egg presence–absence for striped bass Morone saxatilis from five Maryland spawning areas during 1955–1992 to develop criteria for assessing whether upper Chesapeake Bay spawning stock was at a level providing high and stable recruitment or below a level where recruitment declines appreciably. Strong year-classes did not occur when the proportion of tows with eggs (Ep ) fell below 0.60. and the probability of a poor year-class occurring increased greatly as Ep fell below 0.80. Mean recruitment increased and coefficient of variation decreased as Ep rose from 0.40 to 0.80. Highest mean recruitment and lowest coefficient of variation occurred when Ep was at or above 0.80. A probability-based assessment of upper Chesapeake Bay spawningstock recovery indicated a high risk that spawning-stock status did not recover in 1994 and a low risk in 1995. Upper Chesapeake Bay Ep , grew during the late 1950s, was highest and stable during the 1960s, decreased through the 1970s to its nadir in the mid-1980s...