Sciaenidae: L III E3

? Argyrosomus thorpei Smith, 1977.

Squaretail kob


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








35% of NL



Egg: The bright orange/yellow pigment all over the embryo and oil globule, is very like kob (LIIIA8). The egg is however significantly smaller than kob. Black pigment is “stringy”, mostly dorsal on the embryo.  Incubation is about 25 hours.

Larva: The 2-day larva (C) has yellow pigment above and below the tip of the notochord, which disappears over the next 2 days (D). C: 2 days, D: 4 days, E: 12 days, F: 36 days (25-26°C).

Despite only seeing this species on about 10 occasions in 25 years, a batch of 15 eggs yielded the 12 and 36-day larvae seen above. The lack of prominent canines, and general resemblance to kob, of the 36-day juvenile, suggest A. thorpei as the most likely identification of this egg. No hatched larvae have been submitted for DNA barcoding, as the egg has not been seen since 2002.

Linked samples Offshore Inshore
Eggs 1 16
Hits 1 2

This egg was rare off Park Rynie, and was seen only in summer (blue graph). Data from the DHM samples suggests a broader

spring/summer spawning season (green graph), similar to kob (LIIIA8). Park Rynie linked samples are shown for the record,

but numbers were very low, and biased by a single inshore sample containing 15 eggs. See Section 7.3 and Table 1 of the

Introductory Notes, for more information on the linked samples