FISHERY BULLETIN: VOL, 72. NO. 1 



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AGE GROUP 



Figure 2. — ^^Age composition of sampled pound and fyive 

 net catches in the James, York, and Rappahannock rivers, 

 July 1%7-June 1971. 



(Tiller, 1950; Vladykov and Wallace, 1952; 

 Murphy, 1960; Shearer, Ritchie, and Frisbie, 

 1962) and along the migration route in 

 coastal states from Virginia to New England 

 (Merriman, 1941; Schaefer, 1968). Schaefer 

 (1968) concluded that Chesapeake Bay is 

 the primary source of striped bass caught in 

 the surf of Long Island, and that Hudson River 

 stocks may significantly contribute to these 

 populations only when dominant year classes 

 from Chesapeake Bay are unavailable. Yet 

 it is generally believed, although still debatable, 

 that only a small proportion of those striped 

 bass originating in Chesapeake Bay enter the 

 coastal migration (Vladykov and Wallace, 1952; 

 Mansueti, 1961; Massmann and Pacheco, 1961; 

 Grant etal., 1970). 



Koo (1970) has shown an apparent six-year 



Table 4. — Summary of the year classes of striped bass  

 that dominated catches in Virginia rivers, 1967-1971. 



Table 5 — Contribution of age groups I-III to pound net 

 and fyke net catches of striped bass in three Virginia 

 rivers, 1967-1971. 



cycle of abundance in Maryland. Such a cycle 

 could result from the appearance of a dominant 

 year class every six years, followed by three 

 years of high catches (Ages I-III), then three 

 of relatively low catches. The younger age 

 groups (I to III) contribute most to Virginia 

 pound net and fyke net catches of striped bass 

 (Table 5), as expected for nonselective fishing 

 gear. Over 90% of sampled individuals were 

 from age gi-oups I to III, except: 1) 84.7% in 

 the James River during the first year of sam- 

 pling due to catches of large numbers of older 

 fish, particularly the 1958 year class; 2) 84.3% in 

 the York River in the 1970-1971 sampling year; 

 and 3) 85.6% in the Rappahannock River in 

 the same year. The last two exceptions occurred 

 because of contributions by the latest dominant 

 year class (1970 — then Age 0). 



Although the age composition of Virginia 

 catches would seem to conform to Koo's (1970) 

 six-year cycle, no such cycle is apparent in 

 Virginia landings (Figure 1), even though the 

 dominant year classes mentioned by Koo (1970) 

 were also successful ones in Virginia. The 

 difference between Maryland and Virginia 

 landings, relative to this six-year cycle, might 

 stem from local successes of year classes inter- 

 spersed among those appearing at six-year 

 intervals. In addition to the 1958, 1964 and 

 1970 cyclically dominant year classes, certain 

 Virginia rivers have produced large hatches of 

 striped bass in 1961 and 1966 (Grant and 

 Joseph, 1969; Grant, Burrell, and Kriete, 1971). 

 Catches of these aperiodically strong year clas- 



198 



