HOUDE', RICHARDS, and SAKSENA: EGGS AND LARVAE OF SCALED SARDINE 



development. Rearing methods have been de- 

 scribed (Houde and Palko, 1970; Saksena and 

 Houde, 1972). Scaled sardines can be reared 

 successfully at temperatures from 21° to 33.5°C 

 (Saksena, Steinmetz, and Houde, 1972), and 

 salinities have ranged from 29 to 37%o. Larvae 

 and juveniles up to 38.7 mm standard length are 

 included in this description, but we have reared 

 scaled sardines to more than 100 mm in some 

 experiments. 



Morphometries 



Eggs and larvae were measured with an ocular 

 micrometer in a dissecting microscope. The 

 following measurements were made: 



Total length (TD— Tip of snout to end of 

 caudal fin. 



Standard length (SL) — Tip of snout to tip of 

 notochord on small larvae, before notochord 

 flexure; tip of snout to base of hypural plate 

 on larger larvae, after notochord flexure. Unless 

 otherwise noted, all references to lengths of 

 larvae in text refer to standard lengths. 



Preanus length — Tip of snout to anus, measured 

 along midline. This measurement is equivalent to 

 preanal fln length for specimens that have the 

 anal fin developed. 



Predorsal length — Tip of snout to origin of 

 dorsal fin, measured along midline of body. 



Prepelvic length — Tip of snout to origin of pelvic 

 fins, measured along midline of body. 



Head length — Tip of snout to posterior margin 

 of otic capsules in yolk-sac larvae; tip of snout 

 to opercular margin in older larvae. 



Snout length — Tip of snout to anterior margin 

 of eye. 



Eye diameter — Horizontal distance between 

 anterior and posterior edges of the fleshy orbit. 



Body depth — Vertical height of the body at the 

 pectoral symphysis. 



Meristies 



Fin rays were counted in each of the develop- 

 ing fins (Table 4). Myomeres were counted and 

 designated as follows: 



Total myomeres. 



Preanal myomeres: number anterior to the 

 anus. 



Postanal myomeres: number posterior to the 

 anus. 



Predorsal myomeres: number anterior to the 

 dorsal fin origin. 



Postdorsal — preanal myomeres: number be- 

 tween the posterior insertion of the dorsal 

 fin and the anus. 



Osteology 



Sequence of ossification was determined from a 

 total of 16 specimens ranging in length from 4.8 

 to 22.4 mm. They were cleared with trypsin 

 and stained with alizarin using the method of 

 Taylor (1967). Development of the caudal fin 

 bones was examined in detail. Ossification of fin 

 rays, vertebrae, and head bones also was 

 examined. 



DESCRIPTION 

 Description and Occurrence of Embryos 



Ten fertilized eggs from plankton collections 

 were spherical, ranging from 1.55 to 1.78 mm in 

 diameter (mean = 1.66 mm). They had a single, 

 light yellow oil globule ranging from 0.07 to 0.10 

 mm in diameter (mean = 0.09 mm). Measure- 

 ments did not differ from artificially fertilized 

 eggs described by Matsuura (1972). Embryos were 

 well developed when preserved (Figure 6A), 

 and yolk diameters ranged from 0.63 to 0.72 

 mm at that time. The perivitelline space was 

 wide, averaging 589c of the egg diameter for 

 the 10 preserved specimens. In living embryos, 

 the yolk is clearly segmented, but segments are 

 difficult to see in preserved specimens. The 

 chorion is thin, unpigmented, and unsculptured; 

 it is fragile and easily broken compared to most 

 teleost eggs. Preserved embryos had no discern- 

 ible pigment. Living embryos, just prior to hatch- 

 ing, had tiny melanophores, which were diffi- 

 cult to see, in a paired dorsolateral series near 

 the dorsal midline. 



Embryos that were collected from mid-May 

 through July were well developed by noon when 

 our collections were examined (Figure 7). Sur- 

 face water temperatures were 28°C or higher in the 

 spawning area. Spawning presumably occurs only 

 at night because embryos are all at similar 

 stages of development when collected in the 

 morning. Hatching usually began by late after- 



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