Engraulidae: BF III A1
Stolephorus holodon (Boulenger, 1900)
Thorny anchovy
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 |
1295-1455 x680-700 |
1 |
120-130 |
segmented |
narrow |
stern |
80% of NL |
ca. 42 |
Egg: This egg is easily identified by its unique shape, segmented yolk and the presence of an oil globule. Incubation is about 30 hours (24°C).
Larva: The newly hatched larva has the typically elongated gut of an engraulid (B, white arrow). Black pigment spots ventrally on the notochord, do not extend past the anus in this species (C). B: newly hatched, C: 3 days.
Efforts to rear this larva were unsuccessful. Six larvae, hatched from eggs, have been sequenced, and they match 3 locally collected adults (BOLD).
This egg was fairly common in the Park Rynie samples (Introductory notes, Section 7, Table 3), and was the 10th most common egg in the DHM samples. Almost 1500 offshore samples have yielded about 1000 eggs; less than 1 egg per sample. In comparison, the 77 DHM samples of 1990-1994 yielded 986 eggs; an average of almost 13 eggs per sample. This suggests the species has a preference for protected coastal environments. Connell (1996) reported this egg from Lake St Lucia, both from the mouth, while closed to the sea, and from further up the lake, at Charters Creek, while the mouth was open.
Based on the DHM (green) graph it is a spring and summer spawner, from September to February; the Park Rynie (blue) graph is less clear. The egg was especially poorly represented off Park Rynie, in samples after 1998, and showed a similar absence in 1989-1996 (white graph), suggesting the lack of rainfall, and its negative impact on estuaries, has a big impact on this species. See the section on the impact of rainfall and runoff, on spawning patterns, in the Introductory Notes.
Linked samples |
Offshore |
Inshore |
Eggs |
132 |
136 |
Hits |
15 |
26 |
Eggs were equally distributed in the linked samples off Park Rynie, indicating spawning close inshore, in the region of the 20m depth contour. See Section 7.3 and Table 1 of the Introductory Notes, for more information on the linked samples.