DISTRIBUTION AND DURATION OF PELAGIC LIFE OF LARVAE 



OF DOVER SOLE, M1CR0ST0MUS PACIFICUS; REX SOLE, 



GLYPTOCEPHALUS ZACHIRUS; AND PETRALE SOLE, 



EOPSETTAJORDANI, IN WATERS OFF OREGON 



William G. Pearcy, 1 Michael J. Hosie, 2 and Sally L. Richardson 1 



ABSTRACT 



Dover and rex sole larvae attain an exceptionally large size and have a long pelagic life. Dover sole 

 larvae (9-65 mm standard length) were collected in mid-water trawls and plankton nets during all 

 months of the year. Judging from growth of larvae and occurrence in bottom trawls of recently 

 metamorphosed juveniles, Dover sole are pelagic during their first year of life. Large larvae (50-65 mm 

 standard length) are probably pelagic for over a year and few apparently are recruited to benthic 

 populations. Dover sole larvae were most common in oceanic waters beyond the continental slope and 

 in the upper 50 m of the water column. 



The rex sole larvae captured were 5-89 mm long. Average size and stage of development of larvae 

 increased from March through February, and juveniles were common on the bottom during winter on 

 the outer shelf. Thus the pelagic phase usually lasts about a year. Both rex and Dover sole may utilize 

 the outer continental shelf-upper slope region for a nursery during early benthic life. 



Petrale sole larvae (10-22 mm standard length) were rare. They were collected only from March to 

 June and appear to have a pelagic life of about 6 mo. Age-group Ojuveniles, uncommon in bottom trawl 

 collections, were only captured on the inner continental shelf in the fall. 



Dover sole, Microstomus pacificus; petrale sole, 

 Eopsetta jordani; and rex sole, Glyptocephalus 

 zachirus, are commercially important flatfishes of 

 the northeastern Pacific. They ranked first, third, 

 and fourth respectively in 1973 Oregon flatfish 

 landings (Bruneau et al. 3 ). Despite the abundance 

 of Dover, rex, and petrale sole in bottom trawl 

 catches, their larvae are not common in plankton 

 or mid-water trawl collections (Table 1; Ahlstrom 

 and Moser 1975). 



Dover sole apparently spawn in specific sites in 

 offshore waters deeper than 400 m (Hagerman 

 1952; Demory 4 ). Rex sole, which do not appear to 

 have specific spawning sites, spawn between the 

 100- and 300-m depth contours (Hosie 5 ). Petrale 

 sole are known to spawn in fairly well-defined 

 locations in deep water (Ketchen and Forrester 

 1966; Alderdice and Forrester 1971). The rarity of 

 Dover and rex sole larvae may be partially due to 



'School of Oceanography, Oregon State University, Corvallis, 

 OR 97331. 



2 Oregon Department of Fish and Wildlife, Charleston, OR 

 97420. 



3 Bruneau, C, J. M. Meehan, and J. Robinson. 1974. Ground- 

 fish and shrimp investigations. Annu. Rep. 1973, Fish. Comm. 

 Oreg., 25 p. 



"Demory, R. L. 1975. The Dover sole. Oreg. Dep. Fish. Wildl. 

 Inf. Rep. 75-4, 4 p. 



5 Hosie, M. J. 1976. The rex sole. Oreg. Dep. Fish. Wildl. Inf. 

 Rep. 76-2, 5 p. 



Manuscript accepted September 1976. 

 FISHERY BULLETIN: VOL. 75. NO. 1, 1977. 



their reproductive strategy of producing relatively 

 low numbers of large eggs (Table 2). Although 

 development time to hatching is unknown, it is 

 probably long for both Dover sole and rex sole. 

 Petrale sole, on the other hand, produces smaller 

 eggs in greater numbers; yet petrale larvae are 

 perplexingly rare (Table 1). The incidence of lar- 

 val capture of these three species certainly does 

 not reflect their abundance as adults. 



Larvae of two of these pleuronectids are unusual 

 because they attain a large size. The genera 

 Microstomus and Glyptocephalus both have giant 

 larvae. Metamorphosis of Microstomus kitt andM. 

 pacificus larvae takes place at lengths over 30 mm 

 (Norman 1934; Hagerman 1952), and M . pacificus 

 larvae 50 to 60 mm long have been collected ( Table 

 1; Ahlstrom and Moser 1975). We are not aware of 

 published reports on the size at metamorphosis of 

 Glyptocephalus zachirus larvae although 

 Ahlstrom and Moser (1975) stated that it is not 

 unusual to collect larvae that are 50 to 60 mm SL. 

 Metamorphosis in the congeneric G. cynoglossus 

 and G. stelleri occurs at 40 to 60 mm in length 

 (Pertseva-Ostroumova 1961; Okiyama 1963). 



Because they attain a large size, Dover and rex 

 sole larvae presumably have long pelagic lives. 

 Hence they may be susceptible to dispersal and 

 drift by currents for many months, a factor that 



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