Pomatomidae: F III A4

Pomatomus saltatrix (Linnaeus, 1766)

Elf or shad

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
840-960	1	220-265	segmented	narrow	stern	44% of NL	24

Egg: In this egg the stellate yellow (A) and black pigment spots tend to have a separate distribution, and the black pattern on a white background, is a quick check for this egg (B). The yellow pigment is ventral on the embryo, dorsal on the oil globule (usually forming a halo), and just a few spots on the yolk near the oil globule. Black pigment is lateral on the embryo, forming a border around the head and thorax (B), ventral on the oil globule, and scattered on the yolk ventrally, adjacent to the larva (B). Both egg and oil globule, have a light amber hue on a white background. Incubation time is 30-35 hours (24°C).

Larva: The early larva has a distinctive yellow pigment trim to the finfolds (C, D & E), curling into the anus ventrally, where there is a prominent black blotch (D). At 4 days the eyes are pigmented and the yellow pigment has disappeared (F). While still preflexion at 10 days (G), flexion was completed by 14 days (H). At 25 days a complete fin-count was possible (I).  C: 1 day, D: 2 days, E: 2 days, F: 4 days, G: 10 days, H: 14 days, I: 25 days (G & H: 23°C, I: 25°C).

This egg was not successfully reared past 25 days. Three hatched larvae have been sequenced, matching 6 locally collected adults (BOLD).

Shad are summer spawners off Park Rynie, from October to April (blue graph). It was one of the most common eggs, appearing 22nd in Table 3 of the Introductory Notes, but was only seen once in the DHM samples. The annual catch off Park Rynie, shows a regular presence, after an initial peak in 1987 and 1988 (white graph). In the Park Rynie linked samples, the egg showed a slight offshore majority (62%), well below the offshore majority of the two indicator species Argyrosomus japonicus (LIIIA8) and Atractoscion aequidens (LIIA6). See Section 7.3 and Table 1 of the Introductory Notes, for more information on the linked samples.

Linked samples	Offshore	Inshore
Eggs	2363	1447
Hits	114	158

During extended transects, shad egg distribution at Park Rynie was as follows;

Distance offshore in km	8	6.5	5	4	2	0.5
Water depth in metres	100	75	60	50	30	15
19 November 1994	0	0	0	0	0	15
26 November 1994	NS	7	6	2	0	0
3 December 1994	NS	NS	NS	0	17	0
21 January 1995	NS	10	5	9	7	2

NS = not sampled.