posted on June 01, 1985 05:13
David A. Methven
Newfoundland Institute for Cold Ocean Science, Memorial University
St. John's, Newfoundland, Canada A1B 3X7
Source - Journal of Northwest Atlantic Fishery Science, Volume 6(1): 9-20
Pelagic stages of Urophycis chuss, Urophycis tenuis and Phycis chesteri from the Northwest Atlantic were identified by differences in caudal fin-ray and epibranchial gillraker counts, body depth and pigmentation. The adult complement of caudal fin rays in U. chuss (28-34, mean 31.5) and U. tenuis (33-39,mean 36.5) distinguished larvae greater than 7-8 mm SL (standard length). Caudal fin-ray counts in P. chesteri (32-35, mean 33.3) overlapped those of the two Urophycis, U. chuss (3), U. tenuis (2) and P. chesteri (4-5) developed at 12-14 mm in Urophycis and at 16-18mm in P. chesteri. Phycis chesteri was deeper bodied (24.4% SL) than U. tenuis (21.3% SL) which in turn was deeper-bodied than U. chuss(19.3% SL). Pelagic larvae and juveniles of the three species had 3 pelvic fin rays. A size-dependent key to pelagic stages of these species is presented.
Black pigment on pelvic fins of pelagic Urophycis and Phycis was absent in newly-demersal specimens. Differences in pigmentation on the midline, pectoral fin base, dorso-lateral trunk and caudal peduncle helped to separate 5-10 mmUrophycis larvae. Ossification generally occurred at a smaller size in U. chuss than in either U. tenuis or P. chesteri for most of the structures examined. The mandibular arch, dentary, premaxilla, precaudal vertebrae, branchiostegals, cleithra and parasphenoid ossified first. Pelvic fins were the first fins to develop. The first dorsal fin and the pectoral fins developed last.
Language - English
Publisher - Northwest Atlantic Fisheries Organization (NAFO), Dartmouth, N.S., Canada
Publication Date - June 1985
Publication Type - Journal Article