Mugilidae: L III B7

Myxus capensis (Valenciennes, 1836), plus other species.

Freshwater mullet

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
800-920	1	325-370	clear	narrow	stern	60% of NL	24-25

Egg: When fresh, these eggs often have a multiple oil globule (A), but before hatching, they have coalesced. The mixture of yellow and black pigment imparts a brown tint to the embryo and oil globule. Usually the yolk surface is free of pigment, except close to the oil globule (A). Incubation is 30-35 hours.

Larva: The mottled black and yellow larva of B is not the same species as C, and C & D are probably different as well. B: 2 day, C: 3 days, D: 3 days, E: 4 days (22°C).

As noted in LIIIA7, the smaller mullet eggs were simply separated into DHM eggs (LIIIA7) and Park Rynie eggs (this page), although it was assumed there was more than one species at each site. Liza dumerilii was reared from Park Rynie eggs, but DNA barcoding sequences of larvae (BOLD), have yielded matches with adult Myxus capensis (6), Liza tricuspidens (4), and Valamugil seheli(1). Mullet are however, a difficult group to identify, as sub-adults and adults, so these identifications are subject to confirmation, when the voucher specimens have been examined by an expert. Nevertheless there are at least 4 species in this group. Further larval sequencing will probably uncover more species, since there are at least 11 mullet species in the area (Smith & Smith, 1986a, Harrison 2003).

It is not unusual to see small, tightly packed shoals of 50-200 small mullet, in the 10-13mm SL range, on the surface, 2-5km offshore at Park Rynie, especially when driftlines are prominent. The bright silver “saddle” makes them conspicuous. This is the stage at which they enter the surf zone, and recruit into local estuaries (see also LIIIA7).

This egg was common off Park Rynie, but numbers per net haul were usually less than10. Winter and spring were the peak spawning seasons (blue graph). The two biggest peaks in the annual catch (white graph), were due to single samples; aside from which, there has been a steady presence over the years. The Park Rynie linked samples showed slightly more of these eggs offshore

linked samples	Offshore	Inshore
Eggs	223	174
Hits	61	95

(56%), but the low percentage is indicative of a species (or group of species), that are spawning inshore of the 30m contour. See Section 7.3 and Table 1 of the Introductory Notes, for more information on the linked samples.