FISHES OF CHESAPEAKE BAY 
201 
76. Genus SCOMBER Linnaeus. Mackerels 
Body elongate, fusiform; caudal peduncle slender, with two small keels on each side; mouth 
comparatively large; maxillary slipping under the preorbital; teeth small, in a single series on the 
jaws, paired oblique patches on vomer, and in one row on palatines; gill rakers long and slender; 
scales very small, not forming a corselet anteriorly; first dorsal with 10 to 14 feeble spines; second 
dorsal and anal similar, each followed by 5 to 9 finlets; caudal fin small, broadly forked; ventrals 
and pectorals small; air bladder wanting. 
101. Scomber scombrus Linnams. Common mackerel. 
Scomber scombrus Linnaeus, Syst. Nat., ed. X, 1758, p. 297; Atlantic Ocean. Uhler and Lugger, 1876, ed. I, p. 108; ed. II, 
p. 91; Jordan and Evermann, 1896-1900, p. 865, PI. CXXXIII, fig. 303. 
Head 3.6 to 3.8; depth 5.65 to 6; D. XI or XII — 12 — V; A. I, 11 or 12 — V. Body fusiform, 
little compressed; caudal peduncle slender, broader than deep, its depth 10 to 11 in head; head 
long, slender; snout pointed, its length 2.85 to 3.25 in head; eye 4.75 to 5.55; interorbital 4.1 to 
4.75; mouth moderate, terminal, oblique; maxillary reaching nearly to middle of eye, 2.5 in head; 
teeth small, in a single row on jaws, palatines, and vomer; gill rakers long, slender, about 30 on lower 
limb of first arch; scales very small; first dorsal with slender spines, its origin about an eye’s diam- 
eter behind base of pectorals; second dorsal very small, followed by five finlets; caudal fin broadly 
forked; anal fin similar to and opposite second dorsal, also followed by five finlets; ventral fins 
small, inserted under or slightly in advance of vertical from origin of dorsal; pectoral fins short, 
1.9 to 2.2 in head. 
Color bluish black above, with wavy, blackish transverse streaks; bright silvery below; dorsals, 
caudal, and pectorals largely dusky; axil of pectoral black, peritoneum black. 
This species is represented by four small specimens, ranging from 220 to 240 millimeters (8% 
to 9^ inches) in length. 
Garstang (1898, pp. 235-295) made some interesting comparisons among American and 
various groups of European mackerel (all Scomber scombrus) in order to determine what racial 
differences, if any, exist. In this study he utilized 100 fish from Newport, R. I., and 1,549 fish from 
Ireland, the English Channel, and the North Sea. As a result of these studies he indicated that a 
racial difference did exist between American and European mackerel but that this difference is so 
small that it can only be appreciated by an examination of many specimens. 
The number of dorsal spines and rays of the mackerel shows rather wide variation when a large 
series of specimens is examined. The first dorsal usually contains 11, 12, or 13 spines, rarely 10 or 
14. The second dorsal usually contains 12 rays, less frequently 9 to 11 or 13 to 15. 
The mackerel is largely a plankton feeder, subsisting chiefly on pelagic crustaceans as well as 
on fish eggs and fish fry. For a comprehensive account of the feeding habits, spawning, migra- 
tions, etc., of the mackerel see Bigelow and Welsh (1925, pp. 188-208). 
Spawning takes place during the last half of May and throughout the month of June in the 
Massachusetts Bay region and a few weeks later in the Gulf of St. Lawrence. Most of the spawn- 
ing is done at night and when the water temperature ranges from 46° to 61° F. (Bigelow and Welsh, 
p. 208.) The egg is buoyant, from 0.97 to 1.38 millimeters in diameter, and hatches in about 96 
hours at 60° to 62° F., and in about 120 hours at 55° F. 
