Sparidae : L III D9

Rhabdosargus sarba (Forsskal, 1775)

Natal stumpnose

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
790-820	1	170-190	clear	narrow	stern	38% of NL	24

Egg: The dense yellow pigment (mixed with black), extending from behind the head, to past the mid-tail on the embryo (B & C), distinguishes this egg from other sparids. Eggs hatch in 25-30 hours, but shortly before hatching, they become more dense than seawater, and sink.

Larva: Early larva pattern can be broken into patches as in C1 (which may be R. thorpi, see LIIID6), but is more often as in C. The notochord pigment is retained up to 10 days (F). The 18-day larva was still preflexion, but flexion was complete by 30 days (H).B: egg and NH larva, C: 1 day, D: 3 days, E: 5 days, F: 10 days, G: 18 days, H: 30 days, I: 42 days, J: 72 days, K: 102 days.

The pigment pattern has striking similarities to the pinky (EIIIB4), but the clear yolk and oil globule position separate them. The larva proved easy to rear, despite small numbers of eggs, and could prove to be a suitable mariculture species. It is possible that the closely related R. thorpei and R. holubi may have been confused with this species, especially given the range in pattern noted in Plates C and C1 above. However, about 30 specimens were reared to 50 days and more, and all keyed out to R. sarba based on anal fin spine and ray count. Eighteen hatched larvae have been successfully barcoded, matching the sequences of 4 adult R. sarba from the KZN coast (BOLD). A further 5 larvae submitted under this code (LIIID9) have matched the barcode of 6 adult Rhabdosargus holubi collected locally (BOLD).

Linked samples	Offshore	Inshore
Eggs	132	502
Hits	52	158

This egg was foundall year round off Park Rynie (blue graph), which might be due to mixing with R. holubi (LIIID6), since R. sarba is reported to have a narrower spawning season, from August to November (Heemstra and Heemstra 2004). There was however, a distinct peak from June to September. It was the 4^th most common egg in the DHM samples (Introductory notes, Section 7, Table 2), showing a narrower spawning period of May to November, with a peak from June to August (green graph), the same as seen off Park Rynie. Catches of eggs at Park Rynie show no particular trend over the 25-year study period (white graph). The Park Rynie linked samples had more eggs inshore (79%), indicating spawning close inshore (near the surfzone), supported by the frequent occurrence of this egg in the DHM samples. See Section 7.3 and Table 1 of the Introductory Notes, for more information on the linked samples.