PEARCY ET AL.: DISTRIBUTION AND DURATION OF PELAGIC LIFE OF LARVAE 



128° 127° 126° 125° 124° 123° 



FIGURE 1. — Location of sampling stations off Oregon. 



1961-69. These tows were generally oblique from 

 200 m (depth permitting) to the surface at a speed 

 of 5-6 knots. A series of opening-closing mid-water 

 trawl collections (Pearcy et al. in press) was also 

 made 100-150 km off Newport within the upper 

 1,000 m during 1971-74. Considering all the 

 collections, all seasons were sampled about 

 equally. 



Benthic fishes were sampled with a 3-m beam 

 trawl (with 13-mm stretch mesh) on nine cruises 

 during all seasons over the continental shelf off 

 central Oregon (115 collections) and with a 5-m 

 otter trawl on monthly cruises from January 1971 

 to August 1973, 7 to 11 km off Newport. 



LARVAL STAGES 



Standard length (SL) of larvae was measured to 

 the nearest millimeter. Larvae were assigned to 

 an arbitrary developmental stage depending 

 primarily on position of the left eye: 



Stage I: Larvae symmetrical. Left eye has 

 not yet begun to migrate. 



Stage II: From time left eye has begun to 

 migrate to time it is on middorsal 

 ridge of head. The eye is considered 



Stage IV: 



to be on the middorsal ridge when a 

 line extended forward from the 

 dorsal fin transects any part of the 

 eyeball for Dover and petrale sole, 

 or when such a line transects the 

 middle of the eyeball and the 

 eyeball itself is directed upward for 

 rex sole. 



Left eye is on middorsal ridge as 

 defined under Stage II. For Dover 

 sole, this stage was divided into two 

 parts on the basis of pigment 

 pattern, which appeared to corre- 

 late reasonably well with eye 

 migration. 



Five or six dorsal and four or five 

 ventral horizontally elongated 

 streaks of pigment along the cen- 

 tral body musculature. 

 Dorsal and ventral pigmentation 

 streaks along the central body 

 musculature joined to form con- 

 tinuous lines. 



Left eye fully on the right side of 

 head, so that a line extended for- 

 ward from the dorsal fin does not 

 transect any part of the eyeball. 



In Dover sole, the left eye begins to migrate as 

 notochord flexion begins, and the caudal fin is 

 completely formed by the time the eye reaches the 

 middorsal ridge. 7 In rex sole, however, the caudal 

 fin forms completely while the eyes remain 

 symmetrical. Limited evidence suggests petrale 

 may be like Dover sole in this respect. 



GROWTH AND DEVELOPMENT 



The number and length of larvae assigned to 

 developmental stages (Table 3) shows that each 

 stage often included a wide range of sizes. Most of 

 the Dover sole captured were stage I in bongo nets, 

 and metamorphosing stage Ilia larvae in mid- 

 water trawls. Only a few larvae 30-40 mm SL were 

 captured, resulting in a bimodal size-frequency 

 distribution. This may be a sampling artifact due 

 to the unavailability of intermediate-sized larvae 

 to our sampling methods, or it may be caused by 

 rapid growth between stages Ilia and Illb. A 



7 We found one abnormal Dover sole larva, a 43-mm SL tailless 

 fish collected 125 miles off Newport, Oreg., in February 1964. 

 This lack of caudal fin condition has also been reported for post- 

 metamorphosed Dover sole (Demory 1972a). 



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