FISHERY BULLETIN: VOL. 78. NO. 4 



and Damariscotta River estuary systems. Larvae 

 were collected with meter nets, V> m buoyed and 

 anchored nets, and a small beam trawl. The small- 

 est L. putnami larvae (3.1 and 3.6 mm) were 

 hatched from the artificially spawned eggs. The 

 7.1 and 7.6 mm specimens were field collected as 

 small larvae and reared in the laboratory. All 

 other specimens in the series were field collected 

 and preserved. The P. americanus series includes 

 only field-collected specimens. 



Some specimens were lightly stained with aliza- 

 rin to facilitate counting of body parts. Illustra- 

 tions were prepared using a camera lucida. Mea- 

 surements were taken on the right side of each 

 specimen with an ocular micrometer mounted in a 

 dissecting microscope. Measurements taken in- 

 clude: 



Standard length (SL) = snout tip to notochord tip 

 preceding development of caudal fin, then to 

 posterior margin of hypural plate. 



Total length (TL) = snout tip to tip of caudal fin 

 membrane or fin rays. 



Snout to anus length = horizontal distance from 

 snout tip to a vertical through posterior margin 

 of large intestine at anus. 



Head length (HL) = snout tip to posterior margin 

 of otic capsule until cleithrum becomes visible 

 (5.4 mm in L. putnami vs. 3.7 mm in P. 

 americanus), then to the cleithrum; to the pos- 

 terior margin of the operculum on postflexion 

 larvae >7.0 mm of both species. 



Snout length = snout tip to anterior margin of 

 orbit of right eye. 



Upper jaw length = snout tip to posterior margin 

 of maxillary. 



Eye diameter = greatest width of right eye. 



Body depth at pectoral fin base = vertical distance 

 across body at pectoral fin base, not including 

 depth of dorsal fin pterygiophores. 



Maximum body depth at pectoral fin base = verti- 

 cal distance across body at pectoral fin base in- 

 cluding depth of dorsal fin pterygiophores. 



Body depth behind anus = vertical distance across 

 body immediately posterior to anus, not includ- 

 ing depth of dorsal fin pterygiophores. 



Maximum body depth behind anus = vertical dis- 

 tance across body immediately posterior to anus 

 including depth of dorsal fin pterygiophores. 



Pectoral fin length = distance from base to tip of 

 fin fold or longest fin ray. 



Pectoral fin base depth = width of base of pectoral 

 fin. 



Pelvic fin length = distance from insertion of pel- 

 vic fin to tip of fin fold or longest ray. 



Vertebral and fin ray counts were made on 

 juveniles with the aid of radiographs. All length 

 measurements are standard length unless other- 

 wise stated. 



TERMINOLOGY 



Yolk-sac larva = prior to absorption of yolk mate- 

 rial. 



Preflexion larva = prior to notochord flexion. 



Flexion larva = undergoing notochord flexion 

 from time urostyle begins to slant upward until 

 urostyle is in flnal upturned position and caudal 

 fln is formed. 



Postflexion larva = from alignment of urostyle in 

 final upturned position and caudal fin formation 

 until attainment of adult dorsal and anal fin 

 complements. 



Transforming larva = from onset of migration of 

 left eye, development of juvenile pigment pat- 

 tern, and change in behavior from pelagic 

 swimming to benthic habit until completion of 

 these processes and attainment of adult pelvic 

 and pectoral fin ray complements. 



IDENTIFICATION 



Liopsetta putnami and P. americanus are the only 

 Gulf of Maine flatfishes that commonly are found 

 in estuaries and that spawn during late winter- 

 early spring (Bigelow and Schroeder 1953). 

 American plaice, Hippoglossoides platessoides , 

 and Atlantic halibut, Hippoglossus hippoglossus , 

 also spawn during late winter-early spring but 

 rarely enter Gulf of Maine estuaries (Bigelow and 

 Schroeder 1953). Larval Hippoglossoides plates- 

 soides were described by Bigelow and Schroeder 

 (1953) and have three vertical bands of melanistic 

 pigment across the postanal region. Martin and 

 Drewry (1978) compiled and summarized descrip- 

 tions of larval Hippoglossus hippoglossus which 

 lack vertical bands of melanistic pigment across 

 the postanal region and hatch at lengths >8 mm. 

 All yolk-sac larvae collected from Montsweag Bay 

 during March had a single vertical band of 

 melanistic pigment across the postanal region and 

 were <5.2 mm long. 



Since L. putnami spawns from December 

 through February while P. americanus spawms 

 from March through May and eggs take 2 or 3 wk 



898 



