IMMIGRANT RUN MALES 



1977 



1978 



— I 



1979 



1 1 1 1 1 r— 



10 15 20 25 30 35 



DAYS INTO THE RUN 



40 



Figure l. — Percentage of males from samples taken during the 

 escapement run atDamariscotta Lakefishway, Maine, compared 

 with the consistent (1:1) sex ratio of the commercial run, 1977-79. 



each year. The greater proportion of ages III and 

 IV were males, while ages V and VI were domi- 

 nated by females in 1977 and 1979. In 1978 males 

 dominated ages III through V There is no evident 

 trend in ages VII and older for either sex, probably 

 due to the small sample sizes at these ages. The 

 percentage at age of sexes in the escapement runs 



showed about the same distribution as was found 

 in the commercial runs (Table 2). The trend in size 

 and age at the Damariscotta Lake alewife run was 

 larger and older fish arriving early and regressing 

 to smaller and younger fish through time (Table 3). 



Discussion 



There have been other observations of early 

 male alewife predominance in fishways and on 

 spawning grounds. Dominy^ showed a male pre- 

 dominance ratio of 2.4:1 at the start and a 0.7:1 

 ratio by the end of the run in the Gaspereau River, 

 White Rock, Nova Scotia. Kissil (1974) at Bride 

 Lake, Conn., observed more males during the 

 early part of the run declining to an equal number 

 with females for the remainder. Cooper (1961) re- 

 ported that males gradually declined from 65% at 

 the beginning to 35% at the end of the run at 

 Pausacaco Pond, R. I. Rideout (1974) found a high 

 percentage of males in most samples from the 

 Parker River, Mass. Havey (1961) observed a 1.28:1 



^Dominy, C.L. 1971. Evaluation of a pool and weir fishway 

 for passage of alewives (Alosa pseudoharengus) at White Rock, 

 Gaspereau River, Nova Scotia. Dep. Fish. For. Can. Resour. Dev. 

 Branch, Halifax, Progr. Rep. 3:22. 



Table 2. — Percentage of male and female alewives at age from the commercial and escapement runs at the 



Damariscotta Lake fishway, Maine, 1977-79. 



Table 3. — Age distribution (percent) and mean total length (millimeters) of alewives for three equal 

 periods during the Damariscotta Lake, Maine, commercial run, 1977-79. 



209 



