(M:F) ratio at Long Pond, Maine, although this 

 was not statistically significant. 



Sex dominance in a species of fish that is as- 

 sumed to have an equal sex ratio may be attrib- 

 uted to sampling and catch methods. For exam- 

 ple, Casselman (1975) noted that the sex ratio of 

 northern pike, Esox lucius, caught by anglers fa- 

 vored females because of their greater activity in 

 foraging for food at the time of fishing. Early male 

 alewife predominance is attributed to males 

 maturing a year earlier than females (Havey 1961; 

 Kissil 1974) and males ripening earlier in the sea- 

 son, thus beginning the spawning run sooner 

 (Cooper 1961). Marcy (1969) at Bride Lake found 

 that 68% of males were age IV and 68% of females 

 were age V. The alewives in Damariscotta Lake 

 have shown this same attribute of male dominance 

 as in these other investigations. As fish begin 

 entering the lake there were many more males 

 present than females. The presence of signif- 

 icant heterogeneity revealed that this male dom- 

 inance of early escapements into the lake is not 

 consistent throughout the run. A comparison of 

 percentage of males per sample in the fishway 

 run to the hypothetical 1:1 ratio in the commer- 

 cial catch showed a trend of diminishing male 

 dominance. 



The reasons cited earlier for male dominance in 

 alewife runs do not explain the disproportionate 

 ratio in these other runs or at Damariscotta Lake. 

 The theory that earlier maturing or earlier ripen- 

 ing males in an alewife stock contribute to the 

 greater male to female ratio does not correspond to 

 the size and age trend of the Damariscotta spawn- 

 ing runs. As was shown, these runs had the largest 

 fish arriving first. Other investigators have shown 

 this to be the case in other alewife spawning mi- 

 grations: Havey (1961) reported older fish running 

 early; a decreasing trend in mean fork length for 

 each sex during the spawning run was shown by 

 Cooper (1961), Kissil (1974), and Rideout (1974). If 

 larger alewives are the earliest to arrive, the 

 greater proportion of males to females would not 

 occur at the first of the run. The larger proportion 

 of males would occur later or at the end of the run 

 when the younger fish begin arriving. The main 

 reason in searching for other explanations is the 

 fact that the sex ratios in the commercial catch 

 (located near the bottom of the fishway) had gen- 

 erally nonsignificant ratios throughout the run in 

 each of the 3 yr. Age distribution of the commercial 

 catches does show more younger males (III-IV), 

 but the older ages contain more females (V-VII). 



The greatest proportion of the commercial catch 

 (85-90%) is made up of 4- and 5-yr-old fish and they 

 are always present throughout the run. This mix- 

 ing of 4-yr-old males and 5-yr-old females caused 

 the 1:1 sex ratio in the commercial catch. 



The explanation for this abrupt change in the 

 sex ratio from the tidal area to the lake appears to 

 be an effect of the fishway. The greatest dispropor- 

 tionate ratio of male to female alewives occurred 

 at the first part of the escapement run when the 

 largest fish were in the fishway. It seemed that the 

 construction of the fishway was selective against 

 the largest or heaviest fish which were the females 

 at that time. As the size of females tended to de- 

 crease, the male to female ratio became more 

 equal. 



Future investigations that deal with the sex 

 ratio of alewives on the spawning grounds would 

 do well to examine the alewife stock before it made 

 any arduous runs through a difficult section of 

 water or fishway. The reasons for a significantly 

 different sex ratio on the spawning grounds could 

 be from the physical aspects of the migration route 

 rather than any biological factors of the alewife. 



Acknowledgments 



I thank Sherry Collins for her help in the collect- 

 ing and compiling of data, and David Sampson for 

 providing me with his field data. I also thank Jay 

 S. Krouse and Phyllis Carnahan for their review of 

 the text and James Rollins for drafting the figure. 



Literature Cited 

 Atkins, C. G. 



1887. The river fisheries of Maine. In G. B. Goode 

 (editor). The fisheries and fishery industries of the United 

 States. Vol. 1, Sec. 5, p. 673-728. Gov. Print. Off, Wash., 

 D.C. 



BIGELOW, H. B., AND W. C. SCHROEDER. 



1953. Fishes of the Gulf of Maine. U.S. Fish Wildl. Serv., 

 Fish. Bull. 53, 577 p. 



Casselman, J. M. 



1975. Sex ratios of northern pike, Esox lucius Lin- 

 naeus. Trans. Am. Fish. Soc. 104:60-63. 



Gating, J. P. 



1958. Damariscotta (Maine) alewife fishery. Commer 

 Fish. Rev 20(6):l-5. 



Cooper, r. a. 



1961. Early life history and spawning migration of the 

 alewife (Alosa pseudoharengus). M.S. Thesis, Univ. 

 Rhode Island, Kingston, 58 p. 



Havey, K. A. 



1961. Restoration of anadromous alewives at Long Pond, 

 Maine. Trans. Am. Fish. Soc. 90:281-286. 



210 



