Carangidae: E II A2

Seriola dumerili (Risso, 1810), & Seriola lalandi Valenciennes, 1833

Giant yellowtail & greater yellowtail

Egg diameter in µm	Number of oil globules	Diameter of oil globule in µm	Yolk texture	Perivitelline space	Position of oil globule at hatch	Gut length   at eye- pigment stage	Myomeres
1200-1450	1	240-360	segmented	narrow	bow	57% of NL	26

Egg: Until this egg develops pigment on the developing embryo, it is difficult to separate from other similar sized eggs with a clear to bright amber oil globule and segmented yolk, including dorado (FIIA4). But a striking and conspicuous cluster of black pigment soon develops in the trunk of the embryo (C), which instantly sets the egg apart. The yellow and dense black pigment elsewhere on the embryo, is also distinctive (A & B). The hatch time is about 50 hours.    

Larva: Upon hatching, the dense yellow pigment on the dorsal and ventral finfold edges, is dominant (C & D), but is reduced to spots by day 3 (F). By 5 days, the yellow pigment in the finfolds has disappeared (G). D: 1 day, E: 3 days, F: 2 days, G: 5days, H: 6days (24-25°C).

The egg size is a little smaller than seen by Brownell (1979). I was unable to rear this larva, although the most I ever collected in a sample was 7 eggs, insufficient to present a reasonable chance of success in all but a few species. Thirteen larvae have been sequenced; 7 match 2 adult S. lalandi from local waters (BOLD). Four match 5 locally collected Seriola dumerili , and 2 match 1adult Naucrates ductor (BOLD).

Linked samples	Offshore	Inshore
Eggs	69	30
Hits	31	12

This species is a summer spawner in KZN waters, so it is not surprising that Brownell (1979) found it spawning in summer in False Bay. Brownell mentioned Lichia amia as a possible alternative, but their eggs are much larger (see EIA1). The eggs per year trend is decidedly patchy (white graph). The Park Rynie linked samples had 70% offshore, indicating spawning a little shoreward of kob (LIIIA8), in 30-40m water depth, although from local experience, it is more likely around the 50m contour, or deeper. See Section 7.3 and Table 1 of the Introductory Notes, for more information on the linked samples.