eggs from the Atlantic Ocean, they have been well 

 described from the Pacific Ocean, and are similar 

 to eggs of S. scombrus in size and appearance (Fry 

 1936a; Kramer 1960; Watanabe 1970). The most 

 obvious difference between eggs of the two species 

 is the amount of pigment found on the yolk surface 

 during the late or third stage in development. 

 Scomber japonicus develops several melanophores 

 on the yolk while S. scombrus has, at most, a pair 

 of melanophores, as described above. Due to simi- 

 larity of early-stage eggs of the two Scomber 

 species, their identification must depend upon 

 other information, such as spawning area, and the 

 proximity of older identifiable stages. 



In separating Scomber spp. larvae from larvae 

 of other fishes I found the descriptions and illus- 

 trations by Bigelow and Schroeder ( 1953), Kramer 

 ( 1960), and Watanabe (1970) to be especially help- 

 ful. Scomber spp. larvae are characterized by the 

 following: 1) they have 31 myomeres and lack 

 preopercular spines, unlike other scombrid larvae 

 in the western North Atlantic which have more 

 myomeres and possess strong spines; 2) 

 melanophores are present above the forebrain, 

 midbrain, and gut, and along the postanus ventral 

 edge of the trunk; 3) prominent recurved teeth 

 form in larvae by about 4 mm, and are present well 

 into the juvenile stage although somewhat em- 

 bedded and obscured at sizes above about 15 mm; 

 and 4) a large portion of Scomber spp. larvae be- 

 tween about 7 and 15 mm have noticeably subter- 

 minal mouths. 



Other larval fishes found along the U.S. east 

 coast which grossly resemble one or the other of 

 the two Scomber spp. include Sebastes marinus, 

 Pomatomus saltatrix, Centropristis striata, and 

 Stenotomus chrysops. Despite pigmentation 

 similarities myomere counts alone will separate 

 Scomber larvae (with 31 myomeres) from P. sal- 

 tatrix (with 26) and C. striata and Stenotomus 

 chrysops (each with 24 myomeres). Sebastes 

 marinus can have the same number of myomeres 

 (with 30 to 32) as Scomber and is pigmented in 

 most of the same body areas as both species of 

 Scomber. However, at lengths less than about 9 

 mm Sebastes marinus lack teeth and have dorsal 

 and ventral trunk melanophores which are close 

 enough together to appear as dorsal and ventral 

 lines of pigment. Comparably sized Scomber lar- 

 vae have prominent teeth and discrete dorsal and 

 ventral trunk melanophores. Also Sebastes 

 marinus larvae are more slender and have shorter 

 snout-to-anus lengths than Scomber larvae. The 



presence of temporal and preopercular spines on 

 Sebastes marinus and their absence on Scomber 

 larvae separate the two species at lengths >9 mm, 

 before fin-ray counts are distinguishable. 



Treatment of Specimens and Data 



Measurements, as defined by Kramer (1960), 

 made in this study include: standard length 

 (SL = anterior tip of snout to tip of notochord, or to 

 posterior edge of the hypurals after notochord 

 flexure); preanus length (PAL = anterior tip of 

 snout to the most posterior edge of the anus); and 

 body depth (BD = the vertical distance from the 

 dorsal surface of the body directly above the dorsal 

 point of the cleithrum to the ventral point of the 

 cleithrum). Length measurements in this paper 

 are standard lengths, unless otherwise stated. 



Osteological characters in developing Scomber 

 larvae were investigated by examination of bone- 

 stained specimens (Hollister's method in Clothier 

 1950) and radiographs. 



All Scomber eggs in samples containing <400 

 eggs were identified and tabulated. In larger sam- 

 ples, the numbers of S. scombrus eggs were esti- 

 mated from a random subsample of 200. To test the 

 validity of this procedure S. scombrus eggs were 

 identified from seven aliquots of 200 eggs from one 

 sample. No significant differences were found be- 

 tween aliquots (chi-square = 5.415, P = 0.5). 



Lengths for length-frequency diagrams were 

 measured to the nearest 0.1 mm in fish <15 mm 

 and to the nearest 0.5 mm in those >15 mm. Mea- 

 surements were taken of all specimens from sam- 

 ples of 100 or fewer fish and of 50 to 75 randomly 

 selected specimens from larger samples. 



The numbers of Scomber spp. eggs and larvae 

 taken during survey cruises are presented on 

 charts. For these charts the catches from net 1 

 (0-15 m) and net 2 (18-33 m) were combined at 

 stations where both were towed. Before these 

 numbers were plotted some were adjusted in an 

 attempt to standardize the catches. Because net 2 

 spent an estimated 3 min of the V^-h. tow being set 

 and retrieved through the upper 15 m, the catch by 

 net 2 was reduced by 10% of the net 1 catch to 

 correct for contamination. In cases where there 

 was insufficient water depth to allow lowering the 

 plankton net for the standard of six 3-m depth 

 increments, the towing scheme was altered. Dur- 

 ing these tows we sampled for 15 min at each of 

 two levels, or for 10 min at each of three levels. The 

 resulting catch was reduced to one-third when two 



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