Records of the Western Australian Museum 18: 129-134 (1996). 
Description of the eggs and yolk-sac larvae of Whitebait 
Hyperlophus vittatus (Teleostei: Clupeidae) 
R.J. Tregonning, D.J. Gaughan and W.J. Fletcher 
Bernard Bowen Fisheries Research Institute, 
Western Australian Marine Research Laboratories, 
P.O. Box 20, North Beach, Western Australia 6020, Australia 
Abstract - The eggs and early larval (yolk-sac) stages of Hyperlophus vittatus 
are described. The eggs are spherical, range from 0.83 - 0.95 mm in diameter 
(mode = 0.93 mm), have a perivitelline space which occupies 8.6 - 30.9% 
(mode = 14.5%) of the diameter, a coarsely and completely segmented yolk 
and one oil globule (0.025 - 0.075 mm in diameter, mode = 0.048 mm). The 
eggs hatch in 2 - 3 days at a mean temperature of 17°C. The yolk-sac larvae 
are approximately 2.6 mm BL at hatching and lack pigmented eyes or a 
functional mouth. The larvae are elongate and have a long, straight gut (pre- 
anal length = 70 — 79% of BL) with the single oil globule located posteriorly 
in the yolk-sac. The presence of melanophores immediately dorsal of the 
posterior tip of the notochord distinguish the yolk-sac larvae of H. vittatus 
from those of other clupeids in southern Western Australia. 
INTRODUCTION 
Whitebait (Hyperlophus vittatus Castelnau), or 
sandy sprat, their common name elsewhere in 
Australia, is commercially fished in the southwest 
of Western Australia (Goh 1992). The confinement 
of whitebait fishing in this region to beach seining 
operations has restricted the amount of 
information available on the distribution of this 
species. Collecting eggs and larvae using plankton 
nets provides a much more economical means of 
sampling relatively large areas than sampling 
adults. Ichthyoplankton surveys can thus overcome 
the problem of limited data on the distribution of a 
teleost species but requires accurate identification 
of its early life stages. While H. vittatus larvae 5.3 - 
29.1 mm SL have been described (Miskiewicz 
1987), eggs and larvae <5.3 mm SL are 
undescribed. 
The aim of this paper is to provide a description 
of the developmental stages of the fertilized eggs 
and yolk-sac larvae of H. vittatus to facilitate the 
use of ichthyoplankton surveys for determining the 
spatial distribution of spawning whitebait 
populations. The embryogeny of H. vittatus eggs is 
only described sufficiently to identify the eggs of 
this species in plankton collections. 
MATERIALS AND METHODS 
Commercial catches of whitebait in Western 
Australia were monitored through 1993. In early 
August 1993, 12% of a catch of 200-300 kg of 
whitebait from Warnbro Sound (32°20.8'S, 
115°44.5'E) had ripe gonads, suggesting that 
spawning was probably occurring at this region. 
On 17 August 1993, plankton tows were completed 
at several sites within Warnbro Sound, using 60 cm 
diameter bongo nets with 500 pm mesh, towed just 
below the surface at 1 m s' 1 . Fish eggs were 
particularly abundant at one station close to shore, 
sampled at 1200 hours. The surface water 
temperature at this site was 18°C, with a salinity of 
35.1. The plankton sample from this tow was taken 
back to the laboratory, so that fish eggs could be 
removed and reared. 
Culturing of the eggs past hatching was 
necessary since their identification required 
identification of the resultant larvae. Although H. 
vittatus larvae <5.3 mm SL have not been 
described, individuals smaller than this have 
previously been identified (e.g., Gaughan et al. 
1990) using Miskiewicz (1987) as a baseline from 
which to examine a series of sequentially smaller 
whitebait larvae, which were identified by their 
elongate shape, the relative length of the gut and 
the pattern of pigmentation. 
At the laboratory, fish eggs were siphoned off 
from the plankton sample and sorted using a 
stereomicroscope. Two types of eggs were 
abundant in the sample. Approximately 100 eggs 
of one of these types, which exhibited the 
characteristics of clupeid eggs, were selected for 
culturing. These characteristics were the spherical 
shape, the presence of a segmented yolk and a 
single oil globule (Ahlstrom and Moser 1980; 
McGowan and Berry 1984). 
