Scombridae: M II A2
Sarda orientalis (Temminck & Schlegel, 1844) & Sarda sarda (Bloch, 1793)
Striped bonito
|
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 |
|
1200-1370 |
multiple |
NA |
clear |
narrow |
ventral |
41% of NL |
39 |
.
Egg: The egg was usually seen with a partly developed embryo, and 3-20 light amber oil globules, the largest of which was about 240µm (A & B). Black and yellow pigment spots cover the larva and yolk, mostly superimposed, giving them a green tint. The black spots vary from stellate to sickle-shaped or triangular. Incubation is 45-50 hours.
Larva: The 1-day larva has a distinctly green-speckled finfold edge, both dorsally and ventrally (C), which persists to day 4 (D). By day 6 it has turned yellow and is confined to just behind the head (E). At this stage the precocious larva is feeding voraciously. The 7-day larvae clearly needs live food (F). At 13 days the larva has completed flexion (G), and the first dorsal is black (G1). C: 1 day, D: 4 days, E: 6 days, F: 7 days, G: 13 days (24°C).
These larvae were easy to rear, and grew surprisingly fast. At 5 days specimens in one batch were feeding on the 5 day larvae of Acanthistius (FIIIA1), which had been placed in the same tank. Two were found locked together the following day (F). Lack of suitable live food prevented rearing past about 14 days, but the larva was already identifiable at that stage. Seven larvae have been sequenced for their DNA barcode, and match sequences of 5 adult Sarda orientalis from Park Rynie (BOLD). Another 2 larvae have provided a different barcode sequence which matches Sarda sarda in BOLD.
| Linked samples | Offshore | Inshore |
| Eggs | 309 | 350 |
| Hits | 53 | 62 |
These eggs were mostly seen in spring (blue graph). They have shown an erratic annual presence off Park Rynie over the study period (white graph). The egg was not seen in the DHM samples. The Park Rynie linked samples had more eggs inshore (53%), indicating spawning is mostly occurring in the vicinity of the 30m depth contour. See Section 7.3 and Table 1 of the Introductory Notes, for more information on the linked samples.