FISHERY BULLETIN: VOL. 80, NO. 3 



280 

 240 



e 200 



e 



C 



160 



1 120 

 c/5 



80 



40 

 



X- 

 o 



Connecticut River (Marcy) 

 Hudson River (Bath) 

 Delaware River (Miller) 

 Patuxent Estuary (Mansueti) 

 Delaware River (Wallace) 

 Roanoke River (Conover) 



± 



J_ 



_L 



_L 



_L 



4 5 6 



Age Group 



8 



10 



Figure 11.— Mean calculated standard lengths for white perch based on present and 



other studies. 



this rapid growth rate estimate could be an arti- 

 fact. Data from more recent year classes (1963- 

 65) show lower rates of growth than observed 

 from the 1959 through 1962 year classes (Marcy 

 and Richards 1974). The Connecticut River pop- 

 ulation may be expanding rapidly and respond- 

 ing to increased population size with reduced 

 rates of growth (Mansueti 1961). 



White perch populations from south of the 

 Hudson River show earlier onset and completion 

 of the annulus. In the Chesapeake region, an- 

 nulus formation begins in April (Mansueti 1961). 

 In the estuarine portions of the Delaware River 

 (Wallace 1971), the timing of annulus formation 

 was shown to be complete by mid-June to early 

 July. Lawler, Matusky and Skelly Engineers 

 (footnote 5) reported that annulus formation in 

 white perch from the Newburgh, N.Y., region of 

 the Hudson River began in May and was com- 

 pleted by early July, essentially the same time 

 observed in the present study. In Lake Ontario 

 (Sheri and Power 1969) annulus formation was 

 completed in July. The Connecticut River white 

 perch (Marcy and Richards 1974) were anoma- 

 lous in the apparent phenological trend of annulus 

 formation, beginning in late March with com- 

 pletion during mid-May. This anomaly may be 

 due to slightly higher average seasonal tempera- 

 tures in the Connecticut River compared with 



those in the Hudson and Delaware Rivers, or it 

 may be related to the fact that Marcy and 

 Richards' ( 1974) studies were apparently carried 

 out on a rapidly expanding population. 



The basic reproductive potential for white 

 perch, expressed as fecundity, appears to vary 

 among the estuarine and freshwater populations 

 studied. In estuarine and tidal rivers, fecundity 

 values are similar throughout the range. White 

 perch from the Roanoke River and Albemarle 

 Sound, N.C., for example, had a mean fecundity 

 of ~56,000 eggs/fish for age groups 3 and 4 (range 

 20,000-90,000; Conover 1958). Thoits (1958), in a 

 generic study of white perch, estimated fecun- 

 dity at 40,000 eggs/female. Hudson River fish 

 fall close to this mean, with fecundity from three 

 independent studies given as 21,000-135,000 (age 

 groups 3 and 4; Holsapple and Foster 1975), 

 39,000-116,000 (Lawler, Matusky and Skelly 

 Engineers footnote 6), and 16,000-161,000 with a 

 mean of ~51,000 eggs/ female in the present 

 study. Variations in the data are most likely re- 

 lated to numbers of females sampled and the dif- 

 ficulty of obtaining fecundity data from a species 

 which spawns over an extended period of time 

 (Thoits 1958; Mansueti 1961; Taub 1969). 



Freshwater lake populations of white perch 

 may produce more eggs than similar groups in 

 estuarine and tidal river systems. Au Clair (1956) 



608 



