hormones, although this would be physiologically 

 and developmentally more complex. In gray and 

 black areas, aggregation of pigment seems to 

 continue, and melanocytes migrate toward the 

 surface from the base of the epidermis until dif- 

 fuse pigment is largely replaced by granular pig- 

 ment. The process is apparently stopped at some 

 point, after which increase in thickness of the 

 epidermis may result in a lower average density of 

 pigment. 



Acknowledgments 



Benjamin Landing offered suggestions for his- 

 tological treatment of samples, and Ernest Link 

 did the actual histological preparation of sections. 

 Photomicrography was done by Tedd Wells. 



Literature Cited 



Fox, D. L. 



1953. Animal biochromes and structural colours. Camb. 

 Univ. Press, Camb., Engl., 379 p. 

 MrrcHELL, E. 



1970. Pigmentation pattern evolution in delphinid ce- 

 taceans: An essay in adaptive coloration. Can. J. Zool. 

 48:717-740. 

 Perrin, W. F. 



1970. Color pattern of the eastern Pacific spotted porpoise 

 Stenella graffmani Lonnberg (Cetacea, Delphini- 

 dae). Zoologica (N.Y.) 54(4): 135- 142. 

 1972. Color patterns of spinner porpoises (Stenella cf. S. 

 longirostrix) of the eastern Pacific and Hawaii, with 

 comments on delphinid pigmentation. Fish. Bull, U.S. 

 70:983-1003. 

 Simpson, J. G., and M. B. Gardner. 



1972. Comparative microscopic anatomy of selected marine 

 mammals. In S. H. Ridgeway (editor). Mammals of the 

 sea, biology and medicine, p. 298-418. Chas. C. Thomas, 

 Springfield, 111. 

 SOKOLOV, V. E. 



1962. Structure of the tegument in cetaceans. Part II. [In 

 Russ.] Nauchn. Dokl. Vysshei Shkoly, Biol. Nauki 3:45-55. 

 Stiglbauer, R. 



1913. Der histologische Bau der Delphinhant mit besonderer 

 Beriicksichtigung der Pigmentierung. Sitzungs- 

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 122, H.II.Abt. 111:17-27. 



Sharon Gwinn 



Division of Natural Sciences 

 University of California 

 Santa Cruz, CA 9506U 



William F. Perrin 



Southwest Fisheries Center La Jolla Laboratory 

 National Marine Fisheries Service, NO A A 

 La Jolla, CA 92037 



OCCURRENCE OF TWO CONGRIDAE 

 LEPTOCEPHALI IN AN ESTUARY 



During the night of 23-24 August 1971, I caught 

 two congrid leptocephali in Montsweag Bay, part 

 of the Sheepscot River-Back River estuary, Wis- 

 casset, on the southern Maine coast. These larvae 

 were identified as conger eel. Conger oceanicus (D. 

 G. Smith, pers. commun., 15 April 1974). The es- 

 tuary was described by Stickney (1959). Recksiek 

 and McCleave (1973) provide additional informa- 

 tion about the estuary and Montsweag Bay. The 

 leptocephali were collected near their sampling 

 station G3 (lat. 43°56'N, long. 69°42'W). Briefly, 

 Montsweag Bay is a shallow (1 m at mean low 

 water) and wide (2.4 km) basin, but it has a narrow 

 channel (9 m deep at mean low water) through 

 most of its length. Narrow openings at its 

 northern and southern ends allow tidal flow. Mean 

 tidal difference is approximately 3 m. Seasonally, 

 water temperature extremes in Montsweag Bay 

 range from 0.0° to 18.5°C. Salinity ranges from 7 

 to 30"/ 00. Gear used was essentially that described 

 by Graham and Venno (1968). 



One larva (98 mm TL) was captured during the 

 flooding tide 1 m below the surface; the other (91 

 mm TL) during the ebbing tide within 3 m of the 

 bottom. Water depth at this location was 

 approximately 9 m at mean low water. During this 

 period, the average salinity was 26.0"/ oo and the 

 average water temperature was 17.7°C. 



Conger eel adults and leptocephali have been 

 reported from the Gulf of Maine (Bigelow and 

 Schroeder 1953), but apparently most leptocephali 

 are found in the western North Atlantic (Schmidt 

 1931). Conger eel leptocephali, however, have 

 never been reported from such low-salinity water. 

 Bigelow and Schroeder (1953) illustrated one 84 

 mm long from Chesapeake Bay, but they do not 

 give the salinity at the collection site. They also 

 state that conger eel leptocephali grow to 150-160 

 mm. Smith (pers. commun., 15 April 1974) com- 

 mented that my specimens were beginning to 

 metamorphose since the gut of each had shortened 

 noticeably. Conger eel leptocephali apparently are 

 able to tolerate this low-salinity water at least 

 during metamorphosis. 



If conger eel leptocephali typically grow to the 

 size reported by Bigelow and Schroeder (1953), 

 then they must shrink tremendously in length 

 during metamorphosis. My specimens probably 

 shrank during storage, but probably not enough to 

 account for that much size difference. 



444 



