96 Stephen J. Walsh and Brooks M. Burr 



produced is correlated with an increase in egg size. Increased egg size 

 may result in a greater survival rate of fry, thereby countering the effects 

 of reduced fecundity. Adults maturing at smaller sizes apparently divert 

 a higher percentage of metabolic energy from growth to greater repro- 

 ductive efficiency. 



Only two species of lamprey, both nonparasitic, have been documented 

 to have characteristics of neoteny — the European Lampetra zanan- 

 dreai (Zanandrea 1957, 1961), and Lampetra lethophaga (Hubbs 1971) 

 of northern California. During the spawning season, Zanandrea (1961) 

 found 12 female ammocoetes of L. zanandreai that were in an advanced 

 ("third") stage of ovarian development. The type of neoteny described 

 by Hubbs (1971) for L. lethophaga involved "the maturing of appar- 

 ently all individuals of both sexes in the prenuptial condition." 



In Terrapin Creek, from late February through early June (the 

 spawning season has variedgreatly in the last three years, because win- 

 ters have varied in severity), 7 neotenic males and 6 females were col- 

 lected. They had passed through partial transformation but, although 

 some were in full maturity (Fig. 5D shows a females turgid with ripe 

 ova) none had developed the ordinary nuptial attributes (e.g., eye 

 diameter, melanistic pigmentation, englargement of the two dorsal fins, 

 development of the anal pseudo-fin, and enlargement of the disc). Three 

 neotenic females from late February have large, ripe ova visible through 

 the transparent body wall, a distinctive characteristic of mature females. 

 Thus, a situation very similar to that reported by Hubbs (1971) for L. 

 lethophaga seems to also have developed in the Terrapin Creek popula- 

 tion of L. aepyptera. This is apparently the normal condition for the 

 Terrapin Creek population, inasmuch as numerous collections contain 

 no nuptial adults, which are the kind of adults normally collected dur- 

 ing the spring throughout the remainder of Kentucky (Fig. 5A, C). 

 Since temperatures in Terrapin Creek are similar to those of other 

 streams that contain normal adults of L. aepyptera, unusual tempera- 

 tures are ruled out as a factor suppressing nuptial development. 



The low K values of L. aepyptera in Terrapin Creek, and overall 

 low numbers of fishes in a stream that otherwise maintains a diversity of 

 at least 30 species (Table 3), indicate that food may be scarce. The fail- 

 ure of this population to exhibit normal secondary sexual characters is 

 tentatively attributed to limited food during the ammocoete stage, with 

 a resultant lack of sufficient lipid accumulation to bring about the com- 

 pletion of transformation to fully nuptial adults. 



