318 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



Figure 175. — Mackerel (Scomber scombrus). A, egg (European), after Holt; B, larva, 3.5 mm.; C, larva, 4.6 mm.; 

 D, larva, 7.8 mm.; E, larva, 15 mm.; B-E, drawings by Luella E. Cable. 



gelatinous mass in the form of two scales, a for- 

 ward and a hinder, which cover the eye except for 

 a perpendicular slit over the pupil. 



There are two large dorsal fins: the first originat- 

 ing over the middle of the pectoral fins when the 

 latter are laid back is triangular, of 10 to 14 (usually 

 11, 12, or 13) rather weak spines that can be laid 

 down along the midline of the back in a deep 

 groove; the second dorsal, separated from the first 

 by an interspace longer than the length of the 

 latter, is smaller (9 to 15 rays, usually 12) and is 

 followed by several small finlets, of which there 

 are usually 5, but sometimes 4 or 6. The anal fin is 

 similar to the second dorsal in shape and size, 

 originates slightly behind it, and is similarly suc- 

 ceeded by 5 small finlets that correspond to the 

 dorsal finlets in size and shape. The caudal fin is 

 broad, but short and deeply forked. The caudal 

 peduncle bears two small longitudinal keels on 

 either side but no median lateral keel, the absence 

 of the latter being a distinctive character. The 



ventral fins stand below the origin of the first dorsal 

 and are small, as are the pectorals. The scales of 

 the mackerel are so small that its skin feels velvety 

 to the touch ; indeed they are hardly to be seen on 

 the belly with the naked eye, but those about the 

 pectoral fins and on the shoulders are somewhat 

 larger. 



Color. — The upper surface is dark steely to 

 greenish blue, often almost blue-black on the head. 

 The body is barred with 23 to 33 (usually 27 to 30) 

 dark transverse bands 9l that run down in an ir- 

 regular wavy course nearly to the mid-level of the 

 body, below which there is a narrow dark streak 

 running along each side from pectoral to tail fin. 

 The pectorals are black or dusky at the base, the 

 dorsals and caudal are gray or dusky. The jaws 

 and gill covers are silvery. The lower parts of the 

 sides are white with silvery, coppery, or brassy 

 reflections and iridescence; the belly silvery white. 



" Hunt (Copeia, No. 117, pp. 53-59, April, 1923) describes the variations in 

 these stripes among young mackerel. 



