PLEASE RETURN TO NORTHWEST COASTAL INFORMATION CENTER 0 1U MARINE ScIENcE CENTER NEWPORT OREGON 97365 50386730 1 DISTRIBUTION AND DURATION OF PELAGIC LIFE OF LARVAE OF DOVER SOLE, MICROSTOMUS PACiFIC US; REX SOLE, GLYPTOCEPHALUS ZACHIRUS; AND PETRALE SOLE, EOPSETTA JORDANI, IN WATERS OFF OREGON WILLIAM G. PEARCY,' MICHAEL J. HOSIE,2 AND SALLY L. RICHARDSON1 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 çluring 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, their reproductive strategy of producing relatively Eopsetta jordani; and rex sole, Glyptocephalus low numbers of large eggs (Table 2). Although zachirus, are commercially important fiatfishes of development time to hatching is unknown, it is the northeastern Pacific. They ranked first, third, probably long for both Dover sole and rex sole. and fourth respectively in 1973 Oregon flatfish Petrale sole, on the other hand, produces smaller landings (Bruneau et al.3). Despite the abundance eggs in greater numbers; yet petrale larvae are of Dover, rex, and petrale sole in bottom trawl perplexingly rare (Table 1). The incidence of lar- catches, their larvae are not common in plankton val capture of these three species certainly does or mid-water trawl collections (Table 1; Ahlstrorn not reflect their abundance as adults. and Moser 1975). Larvae of two of these pleuronectids are unusual Dover sole apparently spawn in specific sites in because they attain a large size. The genera offshore waters deeper than 400 m (Hagerman Microstomus and Glyptocephalus both have giant 1952; Demory4). Rex sole, which do not appear to larvae. Metamorphosis of Microstomus kitt andM. have specific spawning sites, spawn between the paci/Icus larvae takes place at lengths over 30 mm 100- and 300-rn depth contours (Hosie5). Petrale (Norman 1934; Hagerman 1952), and M.pacificus sole are known to spawn in fairly well-defined larvae 50 to 60mm long have been collected (Table locations in deep water (Ketchen and Forrester 1; Ahlstrom and Moser 1975). We are not aware of 1966; Alderdice and Forrester 1971). The rarity of published reports on the size at metamorphosis of Dover and rex sole larvae may be partially due to Glyptocephalus zachiruslarvae although Ahlstrom and Moser (1975) stated that it is not 'School of Oceanography, Oregon State University, Corvallis, unusual to collect larvae that are 50 to 60 mmSL. OR 97331. Metamorphosis in the congeneric G. cynoglossus 'Oregon Department of Fish and Wildlife, Charleston, OR 97420. and G. stelleri occurs at 40 to 60 mm in length 'Bruneau, C., J. M. Meehan, and J. Robinson. 1974. Ground- (Pertseva-Ostroumova 1961; Okiyama 1963). fish and shrimp investigations. Annu. Rep. 1973, Fish. Comm. Oreg., 25 p. Because they attain a large size, Dover and rex 4Demory, R. L. 1975. The Dover sole. Oreg. Dep. Fish. Wildl. sole larvae presumably have long pelagic lives. Inf. Rep. 75-4, 4 p. 'Hosie, M. J. 1976. The rex sole. Oreg. Dep. Fish. Wildl. Inf. Hence they may be susceptible to dispersal and Rep. 76-2, 5 p. drift by currents for many months, a factor that Manuscript accepted September 1976. 173 1'ISHERY BULLETIN: VOL. 75, NO. 1, 1977. FISHERY BULLETIN: VOL. 75, NO. 1 a) 2 TABLE 2.Egg diameter and fecundity of Dover, rex, and petrale 2 5) 0 225) sole.1 a) E E " E 0COJECOc''5E '-E'--E'E Species Egg diameter No: eggs/female z N ,- E E10 2.04-2.57 mm 51,900 at 42.5 cm N N = 0 Dover sole CS 265,800 at 57.5 cm Rex sole 1.98-2.34mm 34,191 at 36cm S 238,144 at 59 cm a) 400,000 at,42 cm -0 a) Petrale sole 1.21-1.25mm 1,200,000 at 57 cm z 'Data from Hagerman 1952; Harry 1959; Alderdice and Forrester 1971 Hart 1973; HoSe 1975; Ahlstrorn and Moser 1975; J. A. Dunn and N. A. Naplin pers. 0 ±E t commun. 2 222 S E C/) C/I 1/) ci Es,10E0)/)s,QE10E,-E0E s,LL z Co ,.-E NE)0EE may affect survival and subsequent year-class N strengths of these species which are known to be 2 variable (Demory and Hosie6). 6D a) OR: c0 CS o ZWa) CO In O)C5N , COLLECTIONS o s,E o OJ N-NCOO) 10 00 CS o0) WNt N 0. - CSa)NQ U) 0 z5 N ,-m a) r z We examined the catches of 593 bongo net tows U) CS N and over 2 200 Isaacs-Kidd Midwater Trawis 0N 000m taken off Oregon to provide information on the 8 distribution, dispersal, and length of larval life of 0 10 0) these three species. The bongo nets had 70-cm 0,-a) N a) !10 5 S mouth diameters with 0.571-mm mesh nets. Tows 0 N '0 N were made obliquely through the water column CO CO CO - from the bottom or 150 m to the surface at a speed of 2-3 knots. Two data sets were examined. One set N ,-OOINN 10 N r'-.- a) consisted of 287 samples collected on an east-west 0.0 transect off Newport, Oreg., at stations 2, 6, 9, 18, 0) 0000) N 10 0 -- 10 10 001010 10 00 a) 1) N N CS 28,37,46,56,65,74,93, and 111km from the coast CS A . ' (Figure 1). Samples were taken every month from . January 1971 to August 1972 except January and . February 1972. The other set consisted of 306 N a)N. samples collected along 12 transects between the 10 0. CS N Columbia River and Cape Blanco, Oreg., with Na) Na) .10 N stations located 2, 9, 18, 28,37,46, and 56km from a) E E § the coast. Samples were taken in March and April I- 1972 and 1973, andMarch 1974 and 1975. Not all stations were sampled on each cruise. Isaacs-Kidd Midwater Trawl collections were op ii s: made with trawls having a mouth width of 1.8, 2.4, 0oE.5o and 3.1 rn, a 5-mm (bar measure) mesh, and a a .9 a a. < ow 8 a ft - 0.5-rn diameter cod end of .0.571-mm mesh at oz z00 o0 stations 28,46, 84, and 120 km offshore (Figure 1). .04:,5 Stations from 158 to 306 km offshore (at 37-km , intervals) were sampled less frequently. Tows t were mainly taken along four transect lines perpendicular to the coast (Figure 1). during Z.'5o >' = 5a).S B s,._C aCa aC S 6Demory, R. L., and M. J. Hosie. 1975. Resource surveys on the - -_ .8, continental shelf of Oregon. Fish Comm. Oreg., Annu. Rep. July . 0 .Szt8 1, 1974 to June 30, 1975, 9 p. 174 PEARCY ET AL.: DISTRIBUTION AND DURATION OF PELAGIC LIFE OF LARVAE to be on the middorsal ridge when a WASH. line extended forward from the A A A A A A A AA dorsal fin transects any part of the ASTORIA 46 A LKMT eyeball for Dover and petrale sole, BONGO-)GR!O) or when such a line transects the o BONGO (SEASONAL) BONGO GRID B SEASONAL) middle of the eyeball and the eyeball itself is directed upward for 45, rex sole. Stage III: Left eye is on middorsal ridge as A A A A A A A AlA NEWPORT defined under Stage II. For Dover / sole, this stage was divided into two ORES. parts on the basis of pigment 44, pattern, which appeared to corre- late reasonably well with eye migration. A A A A A A A A Stage lila: Five or six dorsal and four or five COOS BAY ventral horizontally elongated 43, streaks of pigment along the cen- CAPE BLANCO tral body musculature. 5O Stage Tub: Dorsal and ventral pigmentation OILOMEYERS streaks along the central body BROOKINGS -A A A A A A A 42' musculature joined to form con- CALIF. )2B )27 )2& )25 )24 (23' tinuous lines. Stage IV: Left eye fully on the right side of FIGURE 1 Location of sampling stations off Oregon. head, so that a line extended for- ward from the dorsal fin does not 1961-69. These tows were generally oblique from transect any part of the eyeball. 200 m (depth permitting) to the surface at a speed of 5-6 knots. A series of opening-closing mid-water In Dover sole, the left eye begins to migrate as trawl collections (Pearcy et al.