体長25〜35cm,表層域でプランクトンを食べる。大きな群を作り,ブラジルでは大量に漁獲されるという(Figueiredo and Menezes, 1978),本属は上顎中央部に深い欠刻を有すること,背鰭の最後の鰭条が糸状に延長しないこと,腹縁に稜鱗が発達すること,腹鰭鰭条数が7本であること等により他のニシン類と区別される(Whitehead, 1977a)。アルゼンチンに分布する他の1種,B. aureaとは体側縦列鱗数で異なる。
(稲田伊史)
Material examined:
3 from Argentina (252.1-274.3 mm SL), FSFL EM 68, 70, 695.
Description:
D 16; A 19; P1 14-15; P2 7; ORS 44-46.
HL 30.2-32.2% of SL; ED 3.1-3.8; BD 37.6-39.7; SN 8.3-8.8; IO 7.6-7.9; UJ 13.7-14.1; CP 10.2-10.7; P1L 18.7-19.6; P2L 9.2-9.4; PreD 52.1-52.6.
Body oval and strongly compressed. Head large. Abdominal margin strongly keeled with developed 17 to 18 scutes in front of pelvic fin and 11 scutes between pelvic and anal fins. Dorsal fin situated near middle of body, its last ray not filamentous. Anal fin situated posteriorly and low in height. Mouth oblique, opening on tip of head, lower jaw projecting slightly further forward than upper. Upper jaw with deep median notch. Scales large cycloid. Lateral line obscure. A double line of modified scales before dorsal fin. Gill-rakers very slender and numerous. Back of body greenish blue, sides and belly silvery, fins golden yellow. A large dark spot behind gill-cover.
Distribution:
From Santos, Brazil to the mouth of La Plata, Argentina. Pelagic coastal waters, especially in bays and estuaries, also entering fresh waters.
Remarks:
Size 25 to 35 cm SL. Plankton filter-feeder at surface. Large shoals found along coast, sometimes abundantly caught in Brazil (Figueiredo and Menezes, 1978). This genus differs from other clupeoids by characters such as upper jaw with deep median notch, last dorsal fin ray not filamentous, a series of abdominal scutes present and pelvic fin rays 7. The other Argentine species, B. aurea, differs from this species by the number of oblique rows of scales (Whitehead, 1977a).
(Tadashi INADA)
Distribution of Brevoortia pectinata in Patagonia.
Anterior part of body in dorsal view, with predorsal scale (above). Caudal fin (below).