Scombridae: L III A11A

Euthynnus affinis (Cantor, 1849).

Eastern little tuna.

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
865-960	1	220-265	clear	narrow	stern	42% of NL	39

Egg: This egg is easily comnfused with some of the small carangids (EIIIA6) when seen in the stage shown in Plate A. The confusion arises because the oil globule is not always distinctly tucked under the tail of the developing larva. But a check for a clear yolk, and the time of year, will distinguish this egg. It was also sometimes confused with sparids such as Pachymetopon grande (LIIIB10), but this too is more typically a winter spawner. Incubation is about 30 hours.

Larva: The early larva has a characteristic pattern of yellow (B), and a high myomere count, which immediately identifies this species from all but the other two summer spawning scombrids A. rochei (LIIIA11) and Katsuwonus (LIIIA11B).  By day 4, all yellow pigment had disappeared (C). B: NH, C: 3 days (25-26°C).

Nine larvae from eggs have been barcoded, matching four locally collected adults (BOLD).

Linked samples	Offshore	Inshore
Eggs	113	240
Hits	14	12

This egg was not often seen (or recognised) off Park Rynie, and may have been combined with LIIIA11 in the past. Eggs were only recorded in summer (blue graph), which is when this fish is most abundant in the Park Rynie area. It was not seen in the DHM samples. It has occasionally been quite abundant, with years of total absence (white graph). The Park Rynie linked samples showed most eggs inshore (68%), but this is based on low numbers. See Section 7.3 and Table 1 of the Introductory Notes, for more information on the linked samples.