Gadiformes: L III F1

Unknown

 

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

720-840

1

145-170

clear

 narrow

stern

32% of NL

42

 

Egg: This egg has a pale amber oil globule, and big black pigment spots down the embryo in 2 rows, skirting the head like the frame of a tennis racket. The embryo has an amber hue, and fine yellow pigment spots. Incubation is 25-30 hours.

Larva: The 2-day larva has a mixture of yellow and black pigment, along the notochord from head to midtail (B), but with unpigmented patches in between (B & B1). The anus vents laterally, not extending to the finfold edge (B; white arrow, with black arrows indicating the finfold edge). The dorsal, ventral and caudal finfolds are peppered with yellow dots (B1). The anus still vents laterally in the 4-day larva (C). B: 2 days, C: 4 days (21°C).

The laterally vented gut indicates this as a gadiform (Fahay & Markle 1983, Matarese et. al. 1989, Richards, 2006). No gadids are recorded from KZN waters (Cohen, 1986), but the merlucciid Merluccius capensis is reported as possibly in KZN waters (Cohen 1986). Brownell (1979) collected M. capensis eggs in Cape waters, and his illustration of  hatched larvae, shows finfold pigment but no spotting, and his eggs were larger (950-1050µm). Several morids are known from KZN waters, including Lepidion natalensis and Physiculus natalensis  (Cohen 1986), but both these genera have vertebrae counts >48 (Fahay & Markle 1983). These authors, however, give the vertebrae count of Merluccius as 48-58, whereas Brownell (1979) gives a count of 41-45 for his larval M. capensis. No larvae have been barcoded.

 

Linked samples Offshore Inshore
Eggs 4 13
Hits 3 10

Seldom seen off Park Rynie, but is clearly a winter spawner (blue graph). Not seen in the DHM samples. The Park Rynie linked samples showed more eggs inshore (76%), suggesting spawning on or around the 15m contour (but numbers are very low). See Section 7.3 and Table 1 of the Introductory Notes, for more information on the linked samples