Eggs and yolk-sac larvae of whitebait 
133 
days. They ranged in size from 4.2 to 4.7 mm BL. 
Rearing of H. vittatus larvae beyond the yolk-sac 
stage was unsuccessful with the larvae failing to 
feed on the supplied rotifers and algae. 
Consequently no larvae survived past 8 days. 
DISCUSSION 
Eggs 
Hyperlophus vittatus eggs which were collected at 
1200 hours and already possessed an embryonic 
keel, required a further 50 - 51 hours to hatch. 
Since many clupeoid species spawn at night (e.g., 
Blaxter and Hunter 1982; Sommerton el at. 1993), 
we assumed that the least developed H. vittatus 
eggs collected for culturing had been fertilized 
between 2000 and 0400 hours the night before 
capture. Thus, the development time to hatching 
for H. vittatus eggs, at a mean temperature of 17°C, 
was 58 — 67 hours (2.5 - 3 d). 
Hyperlophus vittatus have eggs which are typical 
of many marine teleosts (Ahlstrom and Moser 
1980; Matarese and Sandknop 1984), being 
spherical with a diameter of about 0.9 mm and 
possessing a single oil globule. Nonetheless, H. 
vittatus eggs can be distinguished from those of 
other species found in plankton collections in 
southwestern Australia by their size, the 
segmented yolk, the relative sizes of the yolk and 
the perivitelline space, and the small oil globule. 
However, in other regions, the initial identification 
of H. vittatus eggs should ideally be carried out on 
the late-stage eggs in which the embryo is well 
developed. In particular, the 2 — 3 melanophores 
dorsal of the notochord tip provide a means of 
identifying late-stage H. vittatus eggs. 
The other clupeid species common in southern 
Western Australian waters are Spratelloides 
robustus, Sardinella lemuru, Sarditiops sagax and 
Etrumeus teres (Hutchins and Swainston 1986). The 
eggs of S. robustus have a gelatinous covering and 
are layed demersally (McGowan and Berry 1984) 
so would not be expected to occur in plankton 
samples. The major features which distinguish H. 
vittatus eggs from those of these other clupeids are 
the size of the egg and the relative width of the 
perivitelline space (Table 1). As is the case with all 
clupeids (McGowan and Berry 1984), the eggs of 
each of these species have segmented yolks. The 
dimensions of the eggs of these other species were 
based on specimens found in plankton samples 
taken in marine waters off southwestern Australia 
and preserved in the same way as the H. vittatus 
eggs used in this study. Baker (1972) provides a 
full description of S. sagax eggs, while figures of 
the eggs of several Sardinella species can be found 
in Bensam (1990). Development of E. teres eggs has 
been described by O'Toole and King (1974). 
Hyperlophus vittatus eggs (diameter of 0.93 mm) 
are smaller than those of S. lemuru 1 (1.30 mm), S. 
sagax (1.44 mm) and E. teres (1.35 mm) (Table 1). 
The perivitelline space occupies 14.5% of the egg 
diameter in H. vittatus, but accounts for 39.7 and 
49.4% of the diameter in S. lemuru and S. sagax 
respectively. Although the relative size of the 
perivitelline space in the eggs of E. teres (18.7%) is 
more similar than these other species to that for H. 
vittatus, the eggs of this former species lack an oil 
globule (Table 1). 
In addition to these features, late-stage It. vittatus 
eggs can be identified by the dorsal melanophores 
on the tail of the embryo and, in fresh specimens, 
the yellow pigment posterior to the oil globule. 
Larvae 
The most easily recognisable feature of the yolk- 
sac larvae of H. vittatus, which can be used to 
distinguish this species from the other clupeid 
larvae which occur in southern Western Australia, 
is the presence of dorsal melanophores near the 
notochord tip. Yolk-sac larvae of S. robustus, S. 
lemuru, S. sagax and E. teres lack these 
melanophores. Likewise, the yolk-sac larvae of 
Engraulis australis, which are similar in body form 
to those of H. vittatus, do not possess 
melanophores dorsal to the notochord tip. 
ACKNOWLEDGEMENTS 
Thanks to Ken White for assisting in the 
collection of the plankton material. This manuscript 
benefited from comments made by staff of the WA 
Marine Research Laboratory and by two 
anonymous referees. 
REFERENCES 
Ahlstrom, E.H. and Moser, H.G. (1980). Characters 
useful in identification of pelagic marine fish eggs. 
California Cooperative Oceanic Fisheries Investigations 
Reports 21: 121-131. 
Baker, A.N. (1972). Reproduction, early life history, and 
age-growth relationships of the New Zealand 
pilchard, Sarditiops neopilchardus (Steindachner). 
Fisheries Research Division blew Zealand Marine 
Department, Fisheries Research Bulletin No 5: 1-64. 
Bensam, P. (1990). A synopsis of the early 
developmental stages of fishes of the genus Sardinella 
Valenciennes from Indian waters with keys for their 
identification. Indian lournal of Fisheries 37: 229-235. 
Blaxter, J.H.S. and Hunter, J.R. (1982). The biology of 
clupeoid fishes. Advances in Marine Biology 20:1-223. 
Gaughan, D.J., Neira, F.J., Beckley, L.E. and Potter, I.C.P. 
(1990). Composition, seasonality and distribution of 
1 The eggs of Sardinella lemuru have been identified but not formally 
described. 
