FISHERY BULLETIN: VOL. 78, NO. 2 



17.1 mm SL 



22.1 mm SL 



Figure 4. — Isopsetta isolepis larvae: 17.1 mm SL and 22.1 mm SL. 



dorsal and anal pterygiophores give the appear- 

 ance of solid lines of pigment. More melanophores 

 appear on the body until all larval pigment is 

 obscured. Additional pigment develops on the dor- 

 sal, anal, and caudal fins along the fin rays. 



Morphology 



Newly hatched reared larvae, 144 h after fertili- 

 zation, range in length from 2.68 to 2.92 mm (X = 

 2.78 mm, based on 50 specimens). The yolk sac 

 extends along the anterior third of the body. The 



mouth is not yet formed. A moderate finfold ex- 

 tends from the head around the posterior part of 

 the body to the anus. The otic capsule is visible on 

 the head behind the unpigmented eye. The mouth 

 is formed by 2 d (3.4-3.5 mm) after hatching. The 

 yolk is nearly gone by 4 d (3.8-4.0 mm) and is no 

 longer visible by 7 d (3.9-4.1 mm). By 11 d (3.3-4.1 

 mm) the previously straight gut begins to coil. The 

 smallest larva identified from plankton collections 

 is 2.9 mm. It has a formed mouth, no remnant of 

 yolk, and its gut has begun to coil. The size discrep- 

 ancy may be an artifact of preservation, or it may 



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