FISHERY BULLETIN: VOL. 73. NO. 1 



took place. A maximum of 96^^ hatching of fer- 

 tihzed eggs was observed at 24°C-20%o. 



Deformed Larvae 



Immediately after hatching, larvae often had 

 curved bodies reflecting the curvature necessi- 

 tated by confinement within the chorion (Figure 

 8), but such larvae soon straightened out. Some 

 larvae, however, had sharply bent or kinked 

 notochords at hatching, a deformity which was 

 irreversible and which prevented normal swim- 

 ming. These deformities were most common at 

 high salinities (40%o and above) and at 30°C. In 

 Series A, salinities of 15 and 20%o produced a 

 high proportion of larvae with a strange deforma- 

 tion, in which the tail was recurved and fused to 



Figure 8. — Newly hatched larvae. A) ventral view of a normal 

 larva, showing curvature often seen just after hatching, 

 24°C-30%o; B) lateral view of a larva with a recurved tail, 

 24°C-20»/oo, Series A. 



the trunk (Figure 8). Up to 789^ of the larvae 

 hatching at 27°C-15%o showed this irreversible 

 deformity in Series A, but the figure was only 

 about 15% at 21°C-15%o and less than 10% at 

 24°C-20%o; with one or two minor exceptions, 

 other treatments in Series A did not produce this 

 particular distortion, and it was not observed in 

 any treatment in Series B. A greater proportion of 

 late-hatching larvae in a given treatment dis- 

 played deformities than early-hatching larvae. 



Larvae hatching at 15 and 20"/oo showed pro- 

 nounced edema (Figure 9). Histological sections 

 showed that the size of the subdermal space was 

 inversely related to sahnity (Figure 10), an os- 

 motic phenomenon which Battle (1929) also ob- 

 served in larvae of Enchelyopus cimbrius. The 

 yolk sac of newly hatched bairdiella larvae was 

 larger and contained more water at lower 

 salinities (May 1972). 



Survival of Starved Larvae 



Besides showing deformities, at high tempera- 

 tures and salinities many larvae died before ex- 

 hausting their yolk supplies. At 45 and 50%o all 

 larvae in Series A were dead within 1 day after 

 hatching, and the same was true of the few 

 hatched larvae at 40%o at 30°C (Figure 11). The 

 time of major mortality and the maximum surviv- 

 al time of starved larvae were inversely propor- 

 tional to temperature and salinity. Because some 

 of the larvae from Series B were used in tests of 

 temperature and salinity tolerance (May 1972), a 

 complete set of survival curves is not available for 

 them. However, estimates of the percentage of 

 larvae surviving to yolk absorption were obtained 

 from the remaining larvae and from larvae in the 

 least stressful conditions in the tolerance experi- 

 ments, and these estimates indicated better larval 

 survival in Series B than in Series A. For example, 

 the Series B curves for 27°C (Figure 12) did not 

 show the high mortality before yolk exhaustion at 

 25 and 35%o seen in Series A, and a similar differ- 

 ence between the two series occurred at 21°C. At 

 24°C-40%o, an estimated 70% of the larvae were 

 alive at yolk exhaustion in Series B, compared 

 with only about 20% in Series A. At the highest 

 temperatures and salinities, however. Series B 

 showed heavy early mortality similar to Series A. 



Viable Hatch 



The percentage hatching of viable larvae (Table 



12 



