ENGLISH SOLE - USGS

REFERENCECOPY Do Not Remove from the Library

U. S. Fish and Wildlife Service Biological Report 82(11.101) National Wetlands Keseorch LenWr TR EL-82-4 July 1989 700 Cajun Dome Boule\/orc!

Species Profiles: Life Histories and Environmental Requirements of Coastal Fishes and Invertebrates (Pacific Northwest)

ENGLISH SOLE

P A C I F I C

O C E A N

. . .~ ...... ~. . ~ ....

Coastal Ecology Group Fish and Wildlife Service Waterways ~xperiment Station U.S. Department of the Interior U.S. Army Corps of Engineers

B i 01 og i c a l Report 82( 11.101) TR EL-82-4 July 1989

Species P r o f i l e s : L i f e Hi s t o r i e s and Envi ronmental Requirements o f Coasta l F ishes and I nve r t eb ra tes ( P a c i f i c Nor thwest)

ENGLISH SOLE

Dennis R. Lassuy Oregon Cooperat ive F ishery Research U n i t

Department o f F i s h e r i e s and Wild1 i f e Oregon S ta te Uni v e r s i t y

104 Nash H a l l C o r v a l l i s , OR 97331 -3803

P ro jec t O f f i c e r Dav id Moran

U.S. F i s h and W i l d l i f e Se rv i ce Na t i ona l Wetlands Research Center

101 0 Gause Boulevard S l i d e l l , LA 70458

Performed f o r

Coasta l Ecology Group Waterways Experiment S t a t i o n U.S. Army Corps of Engineers

Vicksburg, MS 391 80

and

U .S. Department of t h e I n t e r i o r F i s h and W i l d l i f e Serv ice Research and Development

Nat iona l Wetlands Research Center Washington, DC 20240

This s e r i e s shou ld be re fe renced as f o l l o w s :

U.S. F i s h and W i l d l i f e Serv ice. 1983-19 . Species p r o f i l e s : l i f e h i s t o r i e s and env i ronmenta l r equ i rements o f c o a s t x f i s h e s and i n v e r t e b r a t e s . U.S. F i s h W i l d l . Serv. B i o l . Rep. 82(11). U.S. Army Corps o f Engineers, TR EL-82-4.

Th is p r o f i l e shou ld be c i t e d as f o l l o w s :

Lassuy, D. R. 1989. Species p r o f i l e s : l i f e h i s t o r i e s and env i ronmenta l requ i rements o f coas ta l f i s h e s and i n v e r t e b r a t e s ( P a c i f i c Nor thwest ) -- E n g l i s h so le . U.S. F i s h W i l d l . Serv. B i o l . Rep. 82(11.101). U.S. Army Corps o f Engineers, TR EL-82-4. 17 pp.

PREFACE

This species p r o f i l e i s one o f a se r i es on coasta l aquat ic organisms, p r i n c i p a l l y f i s h , o f spor t , commercial, o r eco log ica l importance. The p r o f i l e s are designed t o prov ide coasta l managers, engineers, and b i o l o g i s t s w i t h a b r i e f comprehensive sketch o f t he b i o l o g i c a l c h a r a c t e r i s t i c s and environmental requirements o f t he species and t o descr ibe how popu la t ions o f t h e species may be expected t o r e a c t t o environmental changes caused by coasta l development. Each p r o f i l e has sec t ions on taxonomy, 1 i f e h i s t o r y , eco log ica l r o l e , environmental requirements, and economic importance, i f appl i cab le . A t h ree - r i ng b inder i s used f o r t h i s se r i es so t h a t new p r o f i l e s can be added as they are prepared. Th is p r o j e c t i s j o i n t l y planned and f inanced by t h e U. S. Army Corps o f Engineers and the U.S. F i sh and W i l d l i f e Service.

Suggestions o r questions regarding t h i s r e p o r t should be d i r e c t e d t o one of t he f o l 1 owing addresses.

I n fo rma t ion Trans fer S p e c i a l i s t Nat ional Wetlands Research Center U.S. F i sh and W i l d l i f e Serv ice NASA-Sl i d e l 1 Computer Complex 1010 Gause Boulevard S l i d e l l , LA 70458

U.S. Army Engineer Waterways Experiment S t a t i o n A t ten t i on : WESER-C Post O f f i c e Box 631 Vicksburg, MS 39180

CONVERSION TABLE

M e t r i c t o U.S. Customary

M u l t i p l y

m i l l i m e t e r s (mm) cen t imete rs (cm) meters (m) meters (m) k i lometers (km) k i lomete rs (km)

square meters (m2) 10.76 square k i lomete rs (km2) 0.3861 hectares (ha) 2.471

l i t e r s (1) cub ic meters (m3) cub ic meters (m3)

m i l l i g r a m s (mg) grams (g) k i lograms (kg) m e t r i c tons (t) m e t r i c tons (t)

k i l o c a l o r i e s ( k c a l ) Cel s i us degrees (OC)

U. S. Customary t o M e t r i c

inches 25.40 inches 2.54 f e e t ( f t ) 0.3048 fathoms 1.829 s t a t u t e m i l e s (mi) 1.609 n a u t i c a l m i l e s (nmi) 1.852

square f e e t ( f t2) square m i l e s (mi2) acres

ga l l ons (ga l ) cub ic f e e t (ft3) a c r e - f e e t

ounces (02) ounces (02) pounds ( l b ) pounds ( l b ) s h o r t tons ( ton )

B r i t i s h thermal u n i t s (Btu) Fahrenhei t degrees (OF)

To Obta in

inches inches f e e t fathoms s t a t u t e m i l e s n a u t i c a l m i l e s

square f e e t square m i l e s acres

gal 1 ons cub ic f e e t a c r e - f e e t

ounces ounces pounds pounds s h o r t tons

B r i t i s h thermal u n i t s Fahrenhei t degrees

mi 11 imete rs cen t imete rs meters meters k i lometers k i lometers

square meters square k i l o m e t e r s hectares

'I i t e r s cub ic meters cub ic meters

mi 1 1 i grams grams k i 1 ograms m e t r i c tons m e t r i c tons

k i 1 oca l o r i es Ce ls ius degrees

CONTENTS

PREFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii CONVERS'ION TABLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i v ACKNOWLEDGMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v i

. . . . . . . . . . . . . . . . . . . . . . . NOMENCLATURE/TAXONOMY/RANGE 1 MORPHOLOGY/IDENTIFICATION A I D S . . . . . . . . . . . . . . . . . . . . . . 1 REASONS FOR I N C L U S I O N I N S E R I E S . . . . . . . . . . . . . . . . . . . . . 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . L I F E HISTORY 3

S p a w n i n g a n d L a r v a e . . . . . . . . . . . . . . . . . . . . . . . . . . 3 . . . . . . . . . . . . . . . . . . . . . . . . P o s t l a r v a e a n d J u v e n i l e s 4 A d u l t s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GROWTH 5

MORTAL ITY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 MOVEMENT AND STOCKS . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 D I S E A S E AND PARASITES . . . . . . . . . . . . . . . . . . . . . . . . . . 8 THE F ISHERY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ECOLOGICAL ROLE 9 ENVIRONMENTAL REQUIREMENTS . . . . . . . . . . . . . . . . . . . . . . . . 10

T e m p e r a t u r e . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 S a l i n i t y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 T e m p e r a t u r e / S a l i n i t y I n t e r a c t i o n . . . . . . . . . . . . . . . . . . . . 11 O t h e r E n v i r o n m e n t a l F a c t o r s . . . . . . . . . . . . . . . . . . . . . . 11

AREAS OF CONCERN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2

L I T E R A T U R E C I T E D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

ACKNOWLEDGMENTS

I am p a r t i c u l a r l y g r a t e f u l t o Beth Deiml ing, Dr. E l l e n P i k i t c h , and D r . W i l l i a m Pearcy f o r t h e i r h e l p i n assembl ing t h e i n f o rma t i on f o r t h i s review. I am indeb ted as w e l l t o Ad r i an Hunter f o r h e r p a t i e n c e w i t h an e v e r - d e f e c t i v e word p rocessor and t o severa l Washington, Oregon, Cal i f o r n i a , and B r i t i s h Co lunb ia u n i v e r s i t i e s and agencies f o r t h e i r speedy responses t o i n f o r m a t i o n requests . W i 11 iam Barss (Oregon Department o f F i s h and W i l d l i f e ) , Gordon Kruse (A laska Department of F i s h and Game), and E l l e n P i k i t c h ( U n i v e r s i t y o f Washington) rev iewed t h e manuscr ip t .

F igu re 1. Eng l i sh s o l e ( f rom Har t 1973).

ENGLISH SOLE

... S c i e n t i f i c name Parophrys v e t u l u s (Gi r a r d ) ............ Common name Engl i s h s o l e ( F i g u r e 1 )

Other names .......... This species i s known i n Canada as t h e lemon s o l e and has been c a l l e d t h e p o i n t s o l e ( f o r i t s po in ted head) i n C a l i f o r - n i a . It i s b e l i e v e d t h a t specimens t h a t had been p r e v i o u s l y p laced i n t h e species _ ~ s o p s e t t a i s c h y r a a re a c t u a l l y hyb r i ds o f P. v e t u l u s and P l a t i c h t h y s s t e l l a t u y (-73).

Class .................. Oste ichthyes Order .............. Pl eu ronec t i formes Fami l y ................ Pl euronec t idae

Geographic range: E n g l i s h s o l e a r e known f rom Sebast ian V i zca i no Bay, Ba ja C a l i f o r n i a , Mexico ( l a t . 28' 30' N, long. 11 5' 00' W) t o Unimak Is land , A1 aska ( l a t . 54'30' N, long. 164' W) and occur i n commercial q u a n t i t i e s f rom Santa Barbara, C a l i f o r n i a , t o no r t he rn

Hecate S t r a i t . B r i t i s h Columbia (A1 d e r d i ce and F o r r e s t e r 1968). Depth d i s t r i b u t i o n i s f rom t h e s u r f l i n e t o 550 m (Har t 1973) b u t i t i s uncommon a t depths g r e a t e r t han 146 m (Demory e t a l . 1976; Barss e t a1 . 1977). Commercial abundances occur between 37 m and 126 m ( F o r r e s t e r 1969a). A1 de rd i ce and F o r r e s t e r (1 968) suggested t h a t t h e i n f l u e n c e o f water temperature on egg v i a b i l i t y may l i m i t t h e bound- a r i e s of commerc ia l ly e x p l o i t a b l e popu la t i ons as we1 1 as t h e bound- a r i e s o f q e o q r a ~ h i c d i s t r i b u t i o n . The d i s t r i b u t i o n o f P. ve tu l us i n t h e P a c i f i c NorthweTt r eg ion i s shown i n F i gu re 2.

MORPHOLOGY/ IDENTIFICATION AIDS

Body e longa te , much compressed, d e x t r a l (eyes on t h e r i g h t s i d e ) . Head s lender , w i t h b l u n t l y po in ted snout. Mouth t e r m i n a l , smal l , asymmetr ical , w i t h narrow gape; jaws and t e e t h s t r onges t on b l i n d s ide.

International North Pacific Fisheries Commission

WASHINGTON

50 100 KILOMETERS

CALIFORNIA

OREGON

Figure 2. Dist r ibut ion o f the English sole i n the Pacific Northwest Region.

M a x i l l a r y extends t o fo rward p a r t o f lower eye. Eyes la rge , upper somewhat p o s t e r i o r t o lower , e n t e r i n g p r o f i l e . I n t e r o r b i t a l space narrow, r i d g e high. Dorsal w i t h one sp ine and 72 t o 92 rays, o r i g i nates above midd le of upper eye; anal, 54 t o 72 rays, exposed sp ine b e f o r e fin'; p e l v i c , 6 rays, t h o r a c i c ; p e c t o r a l s t end t o be po in ted ; caudal i m p e r f e c t l y t runca te . Scales imbr ica ted , c y c l o i d a n t e r i o r l y , c t e n o i d p o s t e r i o r l y . L a t e r a l l i n e , 89 t o 105 scales, s l i g h t l y decurved then s t r a i g h t , do r sa l branch long, c l o s e t o do rsa l f i n , extends t o p o i n t over p e c t o r a l f i n . Color , un i f o rm brown t o ye l low-brown on eyed Side; p a l e y e l l o w t o w h i t e on b l i n d s ide, t i n g e d w i t h r edd i sh brown, p a r t i c u l a r l y on head. Young v a r i o u s l y co l o red gray t o brown, m i n u t e l y spot ted, o f t e n w i t h sandy appearance on eyed sur face (see M i s i t a n o 1976 f o r pho tos) ; o f t e n w i t h two y e l l o w l i n e s on b l i n d s i d e a t bases o f do rsa l and anal f i n s . To ta l l e n g t h (TL) t o 57 cm i n females, 47 cm i n males.

D i s t i n g u i s h e d f rom o t h e r f l a t - f i s h e s by a combinat ion of po in ted head, l o n g do rsa l branch o f l a t e r a l 1 ine, and smooth a n t e r i o r / rough p o s t e r i o r s c a l e p a t t e r n . The above d e s c r i p t i o n was abs t rac ted almost e n t i r e l y f rom Clemens and W i l by (1961 ) and Ha r t (1 973).

REASONS FOR INCLUSION I N SERIES

Barss (1976) wro te t h a t among f l a t f i s h e s coastwide, t h e ca t ch o f Eng l i sh s o l e was exceeded o n l y by t h a t o f t h e Dover s o l e and sometimes t h e P e t r a l e so le. Annual coastwide land ings ( f r m C a l i f o r n i a t o B r i t i s h Columbia, round we igh t ) averaged 5,141 m e t r i c t ons ( t ) f rom 1971 t o 1980 w i t h a peak o f 6,680 t i n 1976 (Lynde 1986). As i n many coas ta l mar ine f i shes , t h e j u v e n i l e s o f P. v e t u l u s depend on shal low, nearshore h a b i t a t s as nursery grounds. Ketchen (1956), i n f a c t , a t t r i b u t e d t h e s c a r c i t y o f Eng l i sh s o l e i n no r t he rn B r i t i s h Columbia t o a

l a c k o f s u i t a b l e nursery grounds. Dur ing e a r l y s p r i n g and summer, j u v e n i l e E n g l i s h s o l e a re t h e most abundant f l a t f i s h i n many P a c i f i c coas ta l embayments and e s t u a r i e s (Yok lav i ch 1982). Barss (1976) suggested t h a t Eng l i sh s o l e cou ld b e n e f i t f rom p r o t e c t e d nursery areas.

My own f a v o r i t e "reason f o r i n c l u s i o n " was s t a t e d by Clemens and Y i l b y (1961): "Th is i s t h e cho i ces t o f t h e smal l f l a t f i s h e s , hav ing a very d e l i c a t e f l a v o r . . . ." LIFE HISTORY

Spawning and Larvae

The spawning o f Eng l i sh s o l e has n o t been d i r e c t l y observed. A l l suggested spawning l o c a t i o n s and t imes a r e i n f e r r e d f rom t h e s p a t i a l and temporal d i s t r i b u t i o n o f e i t h e r t u r g i d o r spent females o r t h e egg and l a r v a l stages. The s i t e o f spawning i s s a i d t o be over sand and sand-mud bottoms a t depths of 60-110 m (Ketchen 1956; Barss 1976; Hewi tt 1980). Spawning i s usual l y most i n t e n s e d u r i n g w i n t e r (December t o February) , b u t i s known t o occur i n a l l seasons; peaks vary f rom September t o A p r i l (Laroche and Richardson 1979; Kruse and T y l e r 1983). I n d i v i d u a l Eng l i sh s o l e may spawn i n more t han 1 year , b u t p robab ly do no t spawn s e r i a l l y w i t h i n a g iven season (Har ry 1959; Kruse 1981 ).

There i s no apparent l a t i t u d i n a l t r e n d i n t h e t i m e o f spawning (Laroche and Richardson 1979). However, Kruse and T y l e r (1 983) were a b l e t o develop a s i m u l a t i o n model t h a t exp la i ned most o f t h e v a r i a t i o n i n observed spawning season. T h e i r model was cons t ruc ted f rom t h r e e re1 a t i o n s between tempera- t u r e and aspects o f reproduc t ion : ( 1 ) r a t e of gonadal development i s i n v e r s e l y r e l a t e d t o summer bottom temperature, ( 2 ) spawning i s i n h i b i t e d a t temperatures below 7.8' C, and (3 ) spawning i s de layed by r a p i d i ncrease i n bot tom temperature.

A1 though Engl i s h so le spawn demersal ly, t h e i r eggs are buoyant i n f u l l -s t rength seawater. Reported egg diameter va r i es from 0.89 t o 1.05 nm (Budd 1940; Ors i 1968). Hatching t ime va r i es from 3.5 t o 12 days and depends on both temperature and s a l i n i t y (A lderd ice and Fo r res te r 1968; Orsi 1968). Ors i (1968) provided a d e t a i l e d d e s c r i p t i o n of t h e embryo1 ogy o f t h e Eng l ish so le t h a t inc luded a s e r i e s o f photos and i 11 u s t r a t i o n s of t h e egg and e a r l y l a r v a l stages. He noted t h a t newly hatched l a rvae are 2.8-2.9 mm TL and grow t o 4.6 mm du r ing the 9-10 days ( a t 10.6 O C ) of yo1 k-sac absorpt ion. Ors i a1 so noted t h a t i n t h e absence o f food, t h e l a s t s u r v i v i n g l a rvae d ied a t 14 days.

The l a rvae o f Eng l ish so le are pe lag i c and depend on favorab le cu r ren t pa t te rns f o r t r a n s p o r t t o s u i t a b l e nearshore nursery areas. The du ra t i on o f t h i s pe lag i c l a r v a l stage i s genera l ly c i t e d as 6-10 weeks (Ketchen 1956; Laroche e t a l . 1982). Transformation t o asymmetri ca l morphology and set t lement t o a demersal ex is tence co inc ide as t h e l a rvae reach 18-22 mm TL, a t 60 t o 120 days o f age (Laroche and Richardson 1 979; Rosenberg and La roche 1 982).

Post1 arvae and Juveni 1 es

Eng l ish s o l e s e t t l i n g per iods vary w ide ly even a t t h e same loca- t i o n . Kryg ier and Pearcy (1986) repor ted t h e capture o f metamorphosing so le i n Yaquina Bay, Oregon, from November through Ju ly ; t h e month of maximum dens i t y var ied from November t o May. This p ro t rac ted pe r iod of benth ic recru i tment may r e f l e c t t h e v a r i a b i 1 i t y i n t h e spawning season (Kruse and Ty le r 1983).

A1 though i t had been concluded i n t h e past t h a t es tua r ies alone serve as nursery areas f o r j u v e n i l e Engl ish s o l e (Demory 1971 ; Olson and P r a t t 1973), new evidence suggests t h a t shal low, open coasta l waters may a l so

prov ide j uven i 1 e r e a r i n g h a b i t a t (LaRouche and Hol ton 1979; Rosenberg 1982; Kryg ier and Pearcy 1986). Demory e t a1 . (1 973) 1 i sted t e n Oregon es tua r ies occupied by j u v e n i l e Eng l ish sole. Pos t l a rva l set t lement occurs bo th i n es tua r ies and along sand- bottomed open coast1 ines, p r imar i l y a t depths o f less than 16 m (Laroche and Hol ton 1979; Kryg ier and Pearcy 1986). Growth r a t e o f p o s t - s e t t l ement , 0-age Eng l ish so le i s comparable i n es tua r ies and open coasta l s i t e s (Rosenberg 1982; Kryg ier and Pearcy 1986). The number o f j u v e n i l e s a t open-coast s i t e s , however, decreases sharp ly a f t e r i n i t i a1 set t lement. It i s not y e t known t o what ex ten t t h i s decrease i s due t o t h e m ig ra t i on o f newly s e t t l e d Eng l ish so le from t h e open coast t o es tua r ies (K ryg ie r and Pearcy 1986) o r t o d i f f e r e n t i a l m o r t a l i t y .

A1 t e r n a t e hypotheses, both based i n opt imal fo rag ing theory, have been presented t o e x p l a i n t h e d i s t r i b u t i o n o f p o s t l a r v a l and j u v e n i l e Eng l ish so le w i t h i n es tuar ies . Yoklavich (1982) suggested t h a t t h e i n f l u e n c e o f temperature on growth r a t e may l i m i t t h e d i s t r i b u t i o n o f j u v e n i l e s t o t h e coo ler , deeper channels i n more southern bays bu t favor a wider use o f i n t e r t i d a l h a b i t a t s i n nor thern bays and es tuar ies . Toole (1 980) proposed t h a t t h e d i s t r i b u t i o n o f young Eng l ish so le i n Humboldt Bay cou ld be ex- p la ined as a combined response t o predator and compet i t ion avoidance as w e l l as opt imal prey s i z e a v a i l a b i l i t y . G i ven t h e scope o f t h e hypotheses , both may be cor rec t .

Juveni l e s move t o progress i ve l y deeper waters w i t h growth, and leave t h e nursery areas a t 140-1 50 n TL (Mis i tano 1976; Sopher 1974, as c i t e d i n Toole 1980). This emigra t ion from t h e es tuar ies genera l l y occurs from August through November (Pearcy and Myers 1973; Yoklavich 1982). Again, several a1 t e r n a t i ve cues t o emigrat ion have been proposed, such as tempera- t u r e by Yoklavich (1982) and n iche

s h i f t and c o m p e t i t i o n avoidance by Tool e (1 980). Westrheim (1955) suggested t h a t "perhaps l e s s t han 5% remain i n t h e bay th rough t h e w i n t e r and presumably emigra te i n t h e l a t e w i n t e r o r e a r l y s p r i n g o f t h e i r second year."

Adu l t s

Adu l t Engl i sh s o l e a re a lmost e n t i r e l y absent f rom coas ta l bays and e s t u a r i e s (Westrheim 1955; M i s i t a n o 1976), and a r e g e n e r a l l y r e s t r i c t e d t o o f f s h o r e sand o r sand-mud subs t ra tes (Demory e t a1. 1976; Barss e t a1. 1977; Demory 1984). The depths a t which t h e y a r e most abundant vary from about 20-70 m i n summer t o 40-1 30 m i n w i n t e r (Jow 1969; Barss 1976). This r e s u l t s f rom a seasonal ba thymet r i c m i g r a t i o n which i s u s u a l l y assoc ia ted w i t h a con t rana tan t ( a g a i n s t t h e c u r r e n t ) movement t o and more pass ive movement w i t h t h e c u r r e n t when r e t u r n i n g f rom deeper-water spawning grounds (Ketchen 1956; F o r r e s t e r 1969a ,b).

Male Eng l i sh s o l e mature a t 2-3 years o f age and females a t 3-4 years o f age (Ketchen 1956; Van Cleve and E l -Sayed 1969). Har ry (1 959) r epo r t ed t h a t 50% o f t h e males were mature a t about 22 cm TL, and 50% o f t h e females a t 31 cm TL. A review by Gunderson and Dygert (1988) l i s t s the age o f 50% maturity f o r females as 4 years, and the average female length a t 50% maturity i n an unexpl o i ted popul a t ion as 388 mn. Harry (1959) reported tha t the number of eggs per female ranged from 327,600 f o r a 30-cm f i s h t o over 1.5 m i l l i o n f o r a 43-cm f ish . On the basis o f Harry's data, Demory (1984) calculated the f o l l owing equation:

where: F = f e c u n d i t y (number o f ova)

L = t o t a l l e n g t h (cm).

GROWTH

Rosenberg and Laroche (1 982) d e t a i l e d t h e growth p a t t e r n of l a r v a l , metamorphosing, and e a r l y 0-age Eng l i sh so le . There was a pe r i od o f reduced growth r a t e d u r i n g metamor- phos is between 60 and 120 days of age and 18 t o 22 mm s tandard l e n g t h (SL). A f t e r growth was resumed, t h e newly r e c r u i t e d ben th i c specimens had reached about 34 mm SL a t an age of 200 days (= 0.15 mmlday).

Rosenberg (1 982) c a l c u l a t e d a growth r a t e o f 0.28 mm SL/day f o r E n g l i s h s o l e 140-480 days o ld . K r y g i e r and Pearcy (1986) c a l c u l a t e d a growth r a t e o f 0.37-0.40 mm SL/day f o r f i s h o f a s i m i l a r s i z e range a t t h e same s i t e s (Yaquina Bay and Moolach Beach, Oregon) and t h e same years ( 1 978-79). Rosenberg's c a l c u l a t i o n was based on o t o l i t h ag ing techniques, and K r y g i e r and Pearcy's on modal p rogress ions o f leng th - f requency data. Both r epo r t s , as w e l l as t h a t of Laroche e t a1 . (1982), d iscussed t h e p o s s i b l e e r r o r s o f each technique. K r y g i e r and Pearcy (1986) a l s o es t imated t h a t average d a i l y growth o f f i s h o f t h i s age group was g r e a t e s t (0.46-0.49 mm) i n l a t e s p r i n g t o e a r l y f a l l , and much lower i n w i n t e r (0.26-0.32 mm).

E n g l i s h s o l e have been repo r t ed t o a t t a i n 130-160 mm TL by t h e end of t h e f i r s t yea r o f l i f e (Van Cleve and El -Sayed 1969; Westrheim 1955; Smith and Ni t sos 1969). Yokl a v i ch (1 982) compared t h e r e l a t i v e growth r a t e s of 1 abora to ry - reared 0-age (72-1 14 mm SL) and "age c l a s s 11" (1 56-188 mm SL) P. ve tu l us . For t r i a l s r un a t 13 O C ,

age= grew a t a r a t e of 1.9% and age I1 f i s h a t 0.8% body weight per day. Gross convers ion e f f i c i e n c y , ( t o t a l g r o w t h / t o t a l r a t i o n ) i n terms o f both d r y we igh t and c a l o r i e s , was g r e a t l y reduced f o r age I1 f i s h (12.1% and 17.8%, r e s p e c t i v e l y ) from e f f i c i e n c i e s o f age 0 f i s h (26.8% and 34.5%, r e s p e c t i v e l y ) .

Growth ra tes o f males and females a r e s i m i l a r du r i ng t h e f i r s t 2 years (Barss 1976), bu t females grow f a s t e r t h e r e a f t e r . Van Cleve and El-Sayed ( 1 969), who provided a broad review of several growth s tud ies o f Eng l ish sole, inc luded a l i s t i n g o f von Ber ta lan f f y growth equation constants from t h e i r own and o the r studies. Although the r e l a t i o n o f length t o weight was no t markedly d i f f e r e n t i n males and females (F igure 3), a p l o t o f l e n g t h a t age (F igure 4) c l e a r l y demonstrated t h e i r d i f f e r e n t growth ra tes , p a r t i c u l a r l y as adul ts . Maximum t o t a l length and age i s 57 cm and 17 years f o r females, 49 cm and 15 years f o r males (Fo r res te r 1969a).

1ot.l Length (mm)

Figure 3. Length-weigh t re1 a t i o n s h i p f o r Parophyrys v e t u l us ; redrawn fr& tbl land 19691.

I I . . I

/&@-- 4 -

Female NO.

\/'

Age (year.)

Figure 4. Length-age f o r Eng l ish sole; redrawn f rom Van Cleve and El-Sayed 1969) .

Kreuz e t a l . (1982) reported a March through September growing season f o r a d u l t Eng l ish sole, growth being most rap id i n May and June. Growth r a t e s between t h e i r study l oca t i ons ( A s t o r i a and Coos Bay, Oregon) d i d no t d i f f e r bu t d i d vary s i g n i f i c a n t l y among years. F l uc tua t i ons i n annual growth increments were nega t i ve l y c o r r e l a t e d w i t h a con t i nen ta l she1 f temperature index (which increased w i t h i nc reas ing temperature) f o r peak growth months and growth appeared t o be r e l a t e d t o long-term t rends i n upwel l ing. They a l so concluded t h a t growth "does not seem t o be associated w i t h stock density." The r e l a t i o n s h i p o f growth and matura t ion i n Engl ish s o l e may have changed i n recent years

6

(E l l e n Pi k i t c h , Department o f F i s h e r i e s and W i l d l i f e , Oregon S ta te U n i v e r s i t y , C o r v a l l i s ; pers. comm.), such t h a t sexual m a t u r i t y i s now reached a t a sma l l e r s i z e than was repo r t ed by Harry (1959; see L i f e H i s t o r y sec t i on ) .

MORTAL I TY

M o r t a l i t y i n Eng l i sh so le , as i n n e a r l y a l l f i shes , i s g rea tes t d u r i n g e a r l y 1 i f e - h i s t o r y stages. Several researchers have c o r r e l a t e d year -c lass s t r e n g t h w i t h t h e e x t e n t and t i m e of spawning and t h e success fu l ben th i c r ec ru i tmen t o f p e l a g i c egg and l a r v a l s tages (Ketchen 1956; Hayman and T y l e r 1980; Kruse 1984). Sources o f m o r t a l i t y f o r eggs, la rvae , and newly r e c r u i t e d j u v e n i l e s i n c l u d e adverse temperature and s a l i n i t y c o n d i t i o n s (A1 de rd i ce and F o r r e s t e r 1968), p r e d a t i o n (Rosenberg 1982), adverse ocean advec t ion (Kruse 1984), and absence o f p rey f o r l a r v a e (Gadomski and Boehl e r t 1984).

Reported annual m o r t a l i t y r a t e s f o r o l d e r f i s h a r e based l a r g e l y on da ta f rom catches i n exper imenta l and commercial t r aw l s . M o r t a l i t y v a r i e s w i d e l y w i t h sex, age, and t h e degree o f e x p l o i t a t i o n . Average annual m o r t a l i t y may be as h igh as 50%-75% i n h i g h l y e x p l o i t e d s tocks (Ketchen 1947, as c i t e d i n Ho l land 1969; Menasveta 1958). Ketchen r e p o r t e d l y es t imated annual n a t u r a l m o r t a l i t i e s i n an unexp lo i t ed p o p u l a t i o n as 30% f o r females, and 38% f o r males. A coastwide r a t e o f annual n a t u r a l m o r t a l i t y o f 23% was repo r t ed by t h e P a c i f i c F i she ry Management Counci 1 ( 1 982). Barss (1976) r epo r t ed a d i f f e r e n t p a t t e r n from e x p l o i t e d s tocks o f f t h e Oregon coast , where m o r t a l i t y was h i g h e r i n females (36%) t han i n males (32%). He suggested t h a t t h e d i f f e r e n c e was due t o t h e h i g h e r suscep t i b i li t y of t h e l a r g e r females t o commercial f i s h i n g pressure. An even more compl icated p i c t u r e was presented by Ho l land ( 1 969). H is i n v e s t i g a t i o n s i n Puget

Sound showed a g r e a t e r m o r t a l i t y f o r females (36%) than males (33%) from t h e t h i r d t o f i f t h years of l i f e a t one s i t e , b u t t h e reverse (males = 38%-50%, females = 27%-48%) f o r 8- t o 10-year-o ld f i s h a t a second s i t e . Golden e t a l . (1986) used a va lue o f 26% average annual f i s h i n g m o r t a l i t y t o r e c o n s t r u c t s tock s i zes o f f t h e Oregon coast . They a l s o es t imated age-speci f i c m o r t a l i t y va lues f o r f i s h f rom 3 t o 13 years o f age.

I n a s tudy o f 20 d i f f e r e n t species o f f i s h t h a t i nc l uded copper r o c k f i s h (Gunderson and Dyger t 1988), t h e instantaneous n a t u r a l m o r t a l i t y r a t e s were p o s i t i v e l y c o r r e l a t e d w i t h t h e gonadosomatic index (GSI) , expressed as gonad we igh t + bodyweight. It may be p o s s i b l e f o r t h i s index t o p r e d i c t t h e n a t u r a l m o r t a l i t y r a t e f o r a f i s h e r y management model o f Engl i s h so le . Note t h a t Gunderson and Dyger t es t imated GSI as 0.18 f o r t h i s species.

MOVEMENT AND STOCKS

Knowledge o f t h e d isc re teness o f popu la t i ons i s i n t e g r a l t o t h e manage- ment of any species. Except f o r b r i e f ment ion by Clemens and Wi lby (1961 ) t h a t Eng l i sh s o l e "move about f r ee l y , " most au thors have concluded t h a t movement i s l a r g e l y r e s t r i c t e d t o seasonal spawning m ig ra t i ons (p re - v i o u s l y d iscussed) i n geog raph i ca l l y segregated s tocks (Ketchen 1956; Jow 1969; P a t t i e 1969; Barss 1976). There may, however, be a smal l b u t h i g h l y m i g r a t o r y f r a c t i o n i n many stocks, as r e p o r t s on most t a g g i n g s t u d i e s have mentioned a t l e a s t one o r a few long- d i s t a n c e recover ies . M i g r a t i o n r a t e s have been as h i g h as 4 mi/day (Har t 1973) and t a g recovery d i s t ances as g rea t as 700 mi (Clemens and Wi lby 1961).

Major spawning popu la t i ons w i t h i n t h e P a c i f i c Northwest r e g i o n have been i d e n t i f i e d f rom Puget Sound (Ho l land

1969), t h e n o r t h e r n Washington coas t ( P a t t i e 1969), t h e c e n t r a l Oregon coas t (Barss 1976), and two s tocks i n no r t he rn and c e n t r a l Cal i f o r n i a t h a t a r e segregated rough l y i n t h e v i c i n i t y o f Eureka (Jow 1969). There i s some i n d i c a t i o n o f m i x i n g near t h e p resc r i bed boundar ies o f severa l s tocks, as we1 1 as ev idence of m u l t i p l e substocks w i t h i n t h e major groupings (Ho l land 1969; F o r r e s t e r 1969b). Day (1976) concluded on t h e b a s i s o f t a g g i n g and recap tu re da ta t h a t Eng l i sh s o l e i n Puget Sound demonstrated "pronounced homing" and suggested t h a t i n d i v i d u a l s may be t e r r i t o r i a l . However, I have found no reco rd o f behav io ra l observa t ions t o s u b s t a n t i a t e t h e poss i b i 1 i ty o f t e r r i t o r i a1 i t y . DISEASE AND PARASITES

01 son (1 978) r epo r t ed on ex tens i ve s t u d i e s o f h o s t - p a r a s i t e re1 a t i o n s i n j u v e n i l e and a d u l t E n g l i s h so le a long t h e Oregon coast. The presence and i n t e n s i t y o f i n f e c t i o n s were r e l a t e d t o t h e h a b i t a t s i n which t h e f i s h were c o l l e c t e d ; i n f e c t i o n was a more se r i ous f a c t o r i n h a b i t a t s w i t h h i ghe r temperature. A t o t a l o f 29 species o f p a r a s i t e s were i d e n t i f i e d . At temperatures above 15 OC, j u v e n i l e s a r e apparen t l y more s u s c e p t i b l e t o a m i c r o s p o r i d i a l i n f e c t i o n capable of caus ing m o r t a l i t y . Angel1 e t a l . ( 1 975) determi ned t h a t an e p i z o o t i c s k i n tumor d isease was a s i g n i f i c a n t cause o f m o r t a l i t y i n a Puget Sound p o p u l a t i o n o f j u v e n i l e Eng l i sh sole.

A rnyxosporidean d isease t h a t causes a "m i l ky ' appearance t o develop i n t h e f l e s h o f some a d u l t Eng l i sh s o l e renders t h e f i s h unmarketable. A "wormy" appearance p resen ts a s i m i l a r marke t ing problem when a d u l t s a r e i n f e c t e d w i t h t h e nematode Ph i lomet ra americana (Hol l a n d 1969; Barss 1976). A l though no ment ion was made o f t h e i r e f f e c t on t h e h e a l t h o f t h e f i s h , n e i t h e r o f these c o n d i t i o n s i s harmful t o human consumers.

THE FISHERY

The E n g l i s h s o l e has been an impo r tan t species i n C a l i f o r n i a t r a w l f i s h e r i e s s i n c e t h e l a t e 1880's (Jow 1969) and a major c o n t r i b u t o r t o bo th t h e Washington and Oregon t r a w l f i s h e r i e s ( P a t t i e 1969; Barss 1976). Landings i n bo th t h e U.S. and Canadian f i s h e r i e s increased d u r i n g t h e yea rs immediate ly a f t e r World War I 1 (Ketchen 1956; Jow 1969). I n U.S. waters, however, t h e ca t ch dec l i ned somewhat w i t h t h e r i s e i n prominence o f t h e Dover s o l e (Jow 1969). Both Dover and E n g l i s h so les a re used i n t h e f i l e t o f s o l e t rade.

Females comprise over 90% of Engl i sh s o l e 1 andi ngs (Kruse 1984; Golden e t a l . 1986). Many mature males, because o f t h e i r sma l l e r s i z e (see s e c t i o n on Growth), a re apparent- l y d iscarded a t sea (Barss 1976). I n 1959-79, i n P a c i f i c Mar ine F i s h e r i e s Commission (PMFC) Area 3A, age-classes 4-7 averaged n e a r l y 80% o f t h e t o t a l 1 andi ngs by we igh t (Kruse 1984). Average weight o f females f o r t h i s area and p e r i o d was 0.45 kg (Kruse 1 984).

The t o t a l we igh t o f Eng l i sh s o l e landed d u r i n g t h e yea rs 1966-85 i n I n t e r n a t i o n a l Nor th P a c i f i c F i she ry Commi ss i on ( I NPFC) Col umbi a area and PMFC Area 3B combined averaged n e a r l y 1,300 t (Golden e t a1 . 1986). However, o n l y one of t h e l a s t 5 years o f t h i s p e r i o d has produced land ings i n excess o f 1,000 t. A s i m i l a r p a t t e r n o f d e c l i n e i s seen i n es t imated biomass i n these same areas. Golden e t a l . ( 1 986) compared survey (catch, e f f o r t , and ca tchab i 1 i t y ) and v i r t u a l popul a- t i o n a n a l y s i s (VPA) es t imates o f Engl i s h s o l e biomass. They " t e n t a t i v e l y concluded" t h a t VPA est imates, which were much lower t han survey es t imates (e.g., 1985, VPA =I 3,030-3,572 t; survey = 5,634 t ) were t h e b e t t e r o f t h e two.

Un fo r t una te l y , t h i s leaves open t h e poss i b i li ty t h a t p a s t es t imates

were t o o h igh o r t h a t a s i g n i f i c a n t amount o f catch i s unaccountable because of nondi r ec ted mu1 t i s p e c i f i c f i s h e r i e s . Parenta l s tock may have been reduced t o a l e v e l a t which f i s h i n g mor ta l i t y adversely a f f e c t s recru i tment . I f so, management op t i ons f o r s tock rehabi 1 i t a t i o n (e.g., t r i p l i m i t s , area c losures, mesh-size r e g u l a t i o n ) a re 1 i m i t e d due t o t h i s m u l t i s p e c i f i c na ture of t he catch. Eng l ish s o l e represent on ly 7% o f t h e t o t a l ca tch f o r a l l Oregon t r a w l f i s h e r i e s i n which they are taken (Golden e t a l . 1986). A l t e r - n a t i v e means of e x p l a i n i n g recent dec l i nes i n recru i tment based on environmental f ac to rs (Ketchen 1956; Hayman and T y l e r 1980; Kruse 1984) have apparent ly no t been app l i ed t o recent oceanographic data (Golden e t a1 . 1986). Growth o f age I f i s h was shown t o be negat ive ly corre la ted w i th densi ty o f the age- I cohort and w i th bottom temperature. Both f ac to rs should be considered i n models of English sole stocks (Peterman and Bradford 1987). A recent model of popul a t i on dynamics o f Engl i sh sole o f f Washington and Oregon achieved best r e s u l t s when i t incorporated the fol lowing: (1 ) the e f f e c t o f ocean temperatures on t ime o f spawning, egg hatching success, and f i s h growth; (2 ) densi ty-dependent 1 arva l mortal i t y ; (3) age-dependent m o r t a l i t y o f f i s h (4 years old; and (4 ) densi ty-dependent growth o f age 1 f i s h (Peterman e t a l . 1987). A management model would f u r t h e r need t o incorporate 1 ong-term changes i n growth schedules ind icated by recent evidence (Peterman e t a l . 1987).

ECOLOGICAL ROLE

Gadomski and Boeh ler t (1984) found i n t h e i r s tudy o f f t he Oregon coast t h a t " the d i e t o f P. ve tu lus 1 arvae i s very s p e c i f i c ; a f iendicula- r i a n s (Oi kopleura spp.) comprised 97% o f t h e t o t a l number o f food i tems consumed" when t h e i r peak abundances coincided. I n t h a t p o r t i o n o f t h e

study when peaks d i d no t co inc ide , appendichlar ians were s t i l l t h e pr imary food i t e m (66%), but t he d i e t a l s o inc luded "o ther food sources such as t i n t i n n i d s , i n v e r t e b r a t e eggs, and naupl i i ." These authors suggested t h a t such apparent dependence on a s p e c i f i c prey "may r e s u l t i n s i g n i f i - cant food-re1 ated mor ta l i t y " i n years when l a r v a l and append icu la r ian peak abundances do no t co inc ide. Hogue and Carey (1 982), who examined t h e guts o f 40 metamorphosing 1 arvae (1 6-1 8 mn SL), found no evidence o f feeding. This l ack of feeding may he lp e x p l a i n t h e occurrence o f a "growth p la teau" d u r i n g metamorphosis (see sec t i on on Growth).

Both Hogue and Carey (1982) and Toole (1 980) found t h a t ha rpac t i co id copepods were a major food source of e a r l y 0-age Eng l i sh sole. Hogue and Carey (1982) found t h a t o ther small p rey such as polychaete palps and j u v e n i l e b i v a l v e s were a l s o important d i e t a r y i tems. A f t e r measuring t h e mouth s i z e o f specimens o f 30 mn (SL), t hey concluded t h a t prey o f g rea te r than 2 mn i n any dimension were t o o l a r g e t o be consumed. Both s tud ies descr ibed a feed ing t r a n s i t i o n w i t h i n 0-age s o l e -- Hogue and Carey (1982) a t 35 mm SL and Toole (1980) a t 50-65 mm TL. This s i z e range co inc ides very n e a r l y w i t h t h e change t o " a d u l t " morphology (Tool e 1980).

Juven i l e Eng l ish so le a re apparent ly o p p o r t u n i s t i c and general - i s t benth ic feeders, w i t h s e l e c t i o n o n l y a t t h e l e v e l of major taxonomic groups o f prey (Toole 1980). W i th in p rey groups, t h e ex ten t o f d i e t a r y i n c l u s i o n va r i es w i t h l o c a l seasonal p rey abundance (Col 1 i n s 1978; Toole 1980; Hogue and Carey 1982). The most commonly mentioned prey i tems i nc lude polychaetes , amphi pods, cumaceans , and b i v a l v e siphons. Hogue and Carey (1982) descr ibed two pa t te rns o f feed ing behavior i n 1 aboratory-held j u v e n i l e s -- t h e f i r s t a s o r t o f s i t - and-wait s t r a t e g y w i t h occasional lunges a t surface prey, and t h e second

a more a c t i v e d i s t u rbance o f t h e upper few mi 11 ime te r s o f sediment and subsequent f eed ing on f l e e i n g prey. I n t h i s same study, da ta on d i e 1 change i n gu t f u l l hess suggested t h a t j u v e n i l e E n g l i s h s o l e a r e p r i m a r i l y d i u r n a l feeders.

Hul be rg and 01 i v e r (1 979), who analyzed t h e taxonomic and " e c o l o g i c a l " compos i t i on o f t h e d i e t s o f a d u l t Eng l i sh s o l e ( x = 228 mm SL) and speck led sanddab (137 mm) f rom Monterey Bay, found cons iderab le taxonomic o v e r l a p i n t h e i r d i e t s . However, behav io ra l and mic rohab i t a t d i f fe rences among p rey spec ies and i n f eed ing behav io r o f t h e two f l a t f i s h e s suggested a c l e a r t r o p h i c separa t ion . The Eng l i sh s o l e fed p r i m a r i l y on s h a l l ow-burrowing, su r f ace -ac t i ve prey, bu t was appa ren t l y capable o f d i g g i n g i n t o t h e sediment t o cap tu re deeper-burrowing p rey as we l l . The sanddab l i m i t e d i t s f eed ing p r i m a r i l y t o hyperben th ic and p e l a g i c prey. A d e t a i l e d taxonomic and numer ica l d e s c r i p t i o n o f t h e d i e t o f l a r g e (230-450 mm TL) E n g l i s h s o l e and f o u r o t h e r f l a t f i s h e s f rom o f f t h e Oregon coas t was presented by K r a v i t z e t a1 . (1976). For t h e s i n g l e day on which f i s h were c o l l e c t e d , t h e d i e t o f P. v e t u l u s was t h e most d i ve r se . Again , amphi pods, po lychaetes , and cumaceans were commonly consumed. L i k e t h e j u v e n i l e s , a d u l t Eng l i sh s o l e feed o p p o r t u n i s t i c a l l y on a wide v a r i e t y o f ben th i c i n v e r t e b r a t e s , such as po lychaetes, shrimp, and smal l mo l luscs and c rabs (Clemens and Wi lby 1961). The polychaetes C a ~ i t e l l a spp. are l ocal 1 y abundant i n d i sturbed areas. I n these areas, English sole exh ib i t s ign i f i can t numerical and s i ze select ion o f t h i s food. Frequency o f C a ~ i t e l l a spp. and median s ize were usual ly s i g n i f i c a n t l y greater i n the f i s h than i n the environment (Becker and Chew 1987). Feeding on t h i s polychaete peaked a t n ight , whereas adult English sole do not usual ly feed then (Becker and Chew 1987). Benthic assembl ages dominated by pioneer species such as C a ~ i t e l l a spp. may have

comparatively high product iv i ty and hence be an enhanced food source. It has not been establ i shed, however, t h a t enhanced populations o f a small number o f species o f prey w i l l provide a heal thy, balanced d i e t (Becker and Chew 1987).

Pe lag i c l a r v a e a r e s u b j e c t t o heavy p r e d a t i o n by appendi c u l a r i ans (Kruse 1984). Toole (1980) no ted a l a c k o f p reda to r s i n t h e i n t e r t i d a l areas used most h e a v i l y by j u v e n i l e s , b u t found a smal l E n g l i s h s o l e i n t h e g u t o f a j u v e n i l e l i n g c o d (Ophiodon e l onga tus ) t h a t was caught i n a nearby e s t u a r i n e channel. Other p o t e n t i a l p reda to r s i n these channels were rock - f i s h , croakers, and sharks. Rosenberg (1982) suggested t h a t a g r e a t e r abundance o f " l a r g e f i s h " represen ted a more s u b s t a n t i a l t h r e a t o f p r e d a t i o n i n t h e open ocean t han i n e s t u a r i n e waters . Ro f f e and Mate (1984) found t h a t P. v e t u l u s c o n s t i t u t e d about 5% o f t h c d i m a c i f i c ha rbor sea l s i n t h e Rogue R iver , Oregon. Seabirds (e.g., cormorants and p igeon g u i l l e - mots) may a l s o p rey on j u v e n i l e so le .

ENVIRONMENTAL REQUIREMENTS

Temperature

Ames e t a1 . (1 978) determined an upper l e t h a l tempera tu re 1 i m i t (50% s u r v i v a l ) f o r P. v e t u l u s o f 26.1 OC.

J uven i l es o f G s s T 119 mm were more s u s c e p t i b l e t han i n t e rmed ia te - s i z e d f i s h . Yok lav ich (1982) found a s i g n i f i c a n t r e d u c t i o n i n j u v e n i l e growth r a t e a t 17.5 O C . Reduced r e l a t i v e growth r a t e was due t o a d e c l i n e i n d a i l y r a t i o n r a t h e r t han i n convers ion e f f i c i e n c y . Yok lav ich f u r t h e r r e l a t e d h i g h temperatures t o t h e d i s t r i b u t i o n of j u v e n i l e s w i t h i n e s t u a r i e s as w e l l as t h e i r t ime of em ig ra t i on f rom e s t u a r i e s , p a r t i c u - l a r l y a t t h e southern marg in of t h e i r geographic range.

Lower l e t h a l temperature 1 i m i t s have been addressed p r i m a r i l y f o r t h e

eggs o f E n g l i s h s o l e . Ketchen (1956) obse rved comp le te m o r t a l i t y and no deve lopment p a s t f i r s t c leavage a t 3.8 "C. A t 7 "C, eggs proceeded t h r o u g h s e v e r a l s t a g e s o f development, h u t a l l d i e d b e f o r e h a t c h i n g . A l d e r d i c e and F o r r e s t e r (1 968) observed comp le te m o r t a l i t y o f eggs a t 20 "C, b u t were a b l e t o a t t a i n a 50% h a t c h i n g success a t 4 "C. A 90% t o t a l h a t c h was e s t i m a t e d t o o c c u r i n t h e t e m p e r a t u r e range o f 7-11 "C. These a u t h o r s conc luded t h a t t e m p e r a t u r e may 1 i m i t abundance a t t h e n o r t h e r n and s o u t h e r n b o u n d a r i e s o f t h e range o f commercial e x p l o i t a t i o n by l o w e r i n g egg v i a b i l i t y , and may b e l e t h a l t o eggs n e a r t h e b o u n d a r i e s o f geograph ic d i s t r i b u t i o n . Kruse (1984) used t h e i r t e m p e r a t u r e - h a t c h success r e l a t i o n and found i t c o n s i s t e n t w i t h Oregon t e m p e r a t u r e s and y e a r - c l ass s t r e n g t h s .

Temperature has a marked i n f l u e n c e on development t i m e (A1 d e r d i c e and F o r r e s t e r 1968). H a t c h i n g o c c u r r e d i n o n l y 3.5 days a t 1 2 "C, b u t r e q u i r e d 11.8 days a t 4 OC. A s i m i l a r s l o w i n g i n t h e development o f l a r v a l E n g l i s h s o l e a t l ow t e m p e r a t u r e s i s c e n t r a l t o t h e e x p l a n a t i o n g i v e n by Ketchen (1956) f o r an observed i n v e r s e r e l a - t i o n s h i p between sea s u r f a c e tempera- t u r e and y e a r - c l a s s s t r e n g t h . It has a l s o been suggested t h a t o c e a n i c t e m p e r a t u r e d u r i n g t h e pre-spawning p e r i o d i n f 1 uences y e a r - c l ass s t r e n g t h (Hayman and T y l e r 1980; Kruse 1984) .

S a l i n i t y

I found no e x p e r i m e n t a l i n fo rma- t i o n on t h e s a l i n i t y t o l e r a n c e o f j u v e n i l e o r a d u l t Engl i s b so le . However, A1 d e r d i c e and F o r r e s t e r (1 968), who i n v e s t i g a t e d t h e e f f e c t s o f s a l i n i t y on h a t c h i n g success, r e p o r t e d t h a t a 90% t o t a l h a t c h was e s t i m a t e d t o o c c u r w i t h i n a s a l i n i t y range o f 17-34 pp t . The b r e a d t h o f t h i s range l e d them t o c o n c l u d e t h a t " o v e r t h e geograph ic range o f t h e spec ies , s a l i n i t y would appear t o have l i t t l e i n f l u e n c e on egg v i a b i l i t y . ' '

T e m ~ e r a t u r e / S a l i n i t v I n t e r a c t i o n

A l d e r d i c e and F o r r e s t e r (1 968) found t h a t t h e " i n t e r a c t i o n e f f e c t o f t e m p e r a t u r e and s a l i n i t y on t o t a l h a t c h i s such t h a t , w i t h i n c r e a s e s ( o r dec reases ) i n s a l i n i ty, maximum s u r v i v a l i s m a i n t a i n e d o n l y w i t h c o u p l e d i n c r e a s e s ( o r dec reases ) i n temperature . " I n t h e i r expe r imen ts , a t e m p e r a t u r e change o f 1 "C was r o u g h l y e q u i v a l e n t ( i n e f f e c t on t o t a l h a t c h ) t o a s a l i n i t y change o f 4 p p t . They f u r t h e r conc luded t h a t opt imum c o n d i t i o n s f o r s u r v i v a l "appeared t o b e a s s o c i a t e d w i t h s a l i n i t i e s and t e m p e r a t u r e s o f 25-28 p p t and 8-9 OC."

O the r Env i ronmen ta l F a c t o r s

A l l demersal l i f e s tages a r e a p p a r e n t l y a s s o c i a t e d w i t h u n c o n s o l i - d a t e d sed iment s u b s t r a t e s . Barss ( 1 976) obse rved t h a t l a b o r a t o r y - h e l d j u v e n i l e s b u r y themse lves and con- c l u d e d t h a t t h e y a r e t h u s l i m i t e d t o a sand bottom. A d u l t s have been c o l - l e c t e d a lmos t e n t i r e l y f r o m sand o r sand-mud s u b s t r a t e s ( B a r s s 1976; Day and Pearcy 1978), t hough Ketchen (1956) r e p o r t e d t h a t a l l E n g l i s h s o l e spawning grounds i n h i s s t u d y were o v e r " s o f t mud" bot toms.

I found no i n f o r m a t i o n on e x p e r i m e n t a l l y d e t e r m i ned d i s s o l v e d oxygen minima f o r j u v e n i l e o r a d u l t E n g l i s h s o l e . However, L e v i n g s (1 980) caugh t d e c r e a s i n g numbers o f Engl i s h s o l e f r o m a B r i t i s h Columbia f j o r d d u r i n g a p e r i o d i n w h i c h d i s s o l v e d oxygen l e v e l s dropped t o 1.0 mg/ l . A f t e r t h i s p o i n t , P. v e t u l u s was no l o n g e r caught. was n o t known whe the r t h i s was due t o e m i g r a t i o n o r t o m o r t a l i t y . A l d e r d i c e and F o r r e s t e r ( 1 968) conc luded t h a t "oxygen i s n o t l i k e l y t o be a c r i t i c a l f a c t o r " i n t h e s u r v i v a l o f p e l a g i c eggs and l a r v a e .

F a i r l y extensive information about the e f fects o f contaminants on English so le i s a v a i l ab le (Krahn e t a1 . 1984; Ma1 ins e t a l . 1984). Johnson e t a l . (1988) repor t t h a t exDosure t o aromatic

hydrocarbons may i n t e r f e r e w i t h ovar ian devel opment .

AREAS OF CONCERN

Perhaps t h e most c r i t i c a l area o f concern i n t h e b i o l o g y o f t h e Eng l i sh s o l e i s i n deve lop ing an unders tand ing o f r ecen t d e c l i n e s i n r e c r u i t m e n t . Such an e f f o r t would r e q u i r e t h e v e r i f i c a t i o n o f causal mechani sms suggested by Ketchen (1956; on i n t e r - a c t i o n of temperature and water

c u r r e n t s d u r i n g t h e l a r v a l s tage) , by Hayman and T y l e r (1980; on p re - spawning tempera tu re c o n d i t i o n s ) , and by Golden e t a l . (1986; on over - e x p l o i t a t i o n o f pa ren t s t ock ) . A c l a r i f i c a t i o n o f p o p u l a t i o n dynamics ( p a r t i c u l a r l y m o r t a l i t y ) i n open coas t1 i n e versus e s t u a r i n e nursery areas i s a l s o needed. O f p a r t i c u l a r concern t o coas ta l development i s t h e poss i b i 1 i t y , p a r t i c u l a r l y a t t h e sou thern marg in o f Eng l i sh s o l e d i s t r i b u t i o n , o f the rma l p o l l u t i o n a l t e r i n g t h e s u i t a b i l i t y o f e x i s t i n g e s t u a r i n e nu r se r y areas.

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Kruse, G. H. 1981. Re la t ionsh ip between shel f temperature, coas ta l sea l e v e l , t h e coasta l upwel l ing index, and Engl i s h so le (Parophrys ve tu lus ) spawning a c t i v i t y o f f

M.S. Thesis. Oregon Sta te Un ive rs i t y , C o r v a l l i s . 68 pp.

Kruse. G.H. 1984. A s imu la t i on model o f Engl ish so le (Paro h r s ve tu lus ) +.m- recru i tment mechanisms s e r t a t i o n . Oregon State Uni ve rs i t y , C o r v a l l i s . 103 pp.

Kruse , G.H., and A.V. Tyler . 1983. S imula t ion o f temperature and upwe l l i ng e f f e c t s on Eng l ish so le (Parophrys v e t u l u s ) spawning season. Can. J. Fish. Aquat. Sci. 40(2) : 230-237.

Kryg ier , E.E., and W.G. Pearcy. 1986. The r o l e o f es tua r ine and o f f sho re nursery areas f o r young Engl ish so le

(Paro h r s ve tu lus G i ra rd ) o f f S . 1 Mar. Fish. Serv. Oregon

Fish. B u l l . 84:119-132.

Laroche, J.L., and S.L. Richardson. 1979. Winter - s p r i n g abundance of l a r v a l Eng l ish sole, Paro h r s + vetulus, between t h e Columbia 1 ver a n d p e Blanco, Oregon, du r i ng 1972-75 w i t h notes on occurrences of 3 o the r p leuronect ids . Estuar ine Coastal Mar. Sci . 8(5) :455-476.

Laroche, J.L., S.L. Richardson, and A. A. Rosenberg. 1982. Age and growth o f a p leu ronec t i d , Paro h r s ve tu lus , du r i ng t h e p e l a g d 6 % pe r iod i n Oregon coasta l waters. U.S. Nat l . Mar. Fish. Serv. Fish. B u l l . 80:93-104.

Laroche, W.A., and R.L. Holton., 1979. Occurrence o f 0-age Ens1 i s h sole. Parophrys v e t u l us, -a long-the Oregon coast: an open coast nursery area? Northwest ~ c i . 53( 2) : 94-96. '

Levings, C. D. 1980. Demersal and benth ic communities i n Howe Sound Basin and t h e i r responses t o d isso lved oxygen def ic iency . Can. Tech. Rep. Fish. Aquat. Sci . 951 :1-27.

Lynde, M. 1986. The h i s t o r i c a l annotated 1 andings (HAL) database: documentation o f annual harves t o f groundf ish from t h e Northeast P a c i f i c and. eastern Ber ing Sea from 1956 t o 1980. NOAA Tech. Memo. FMFS F/NWC-103. 196 pp.

Malins, D.C., M.S. Myers, W. McLeod, and W.T. Roubal. 1984. Organic f r e e r a d i c a l s i n 1 i ver mic~osomes i n Eng l ish sole, Parophrys vetu lus, con ta in ing 1 i v e r les ions . Second I n t e r n a t i o n a l Symposium on Responses o f Marine Organisms t o Pol 1 utants, Woods Hole, MA, 27 A p r i l 1983. Mar. Environ. Res. 14(1-4):537.

Menasveta, D. 1958. M ig ra t i on and f i s h i n g m o r t a l i t y o f Eng l ish so le

(Parophrys v e t u l us) i n Saratoga Passage and adjacent waters. M.S. Thesis. U n i v e r s i t y o f Washington, Seat t le . 84 pp.

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Olson, R.E. 1978. P a r a s i t o l o w o f t h e - Engl i s h sole, Parophrys v e i i l u s , i n Oreqon. USA. J. F i sh B io l .

Olson, R.E., and I. Pra t t . 1973. Paras i tes as i n d i c a t o r s o f Eng l ish s o l e (Paro h r s v e t u l u s ) nursery grounds *. m i s h . Soc.

Ors i , J, 1968. The embryology o f t h e Eng l ish sole, Paro hrys vetu lus. C a l i f . F ish G a m e h 3 - 1 ~

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Van Cleve, R., and S.Z. El-Sayed. 1969. Age, growth, and p r o d u c t i v i t y o f an Engl ish so le (Parophrys wetulus) popu la t ion i n Puget Sound, Washington. Pac. Mar. Fish. Comm. B u l l . 7: 51 -71 .

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eds. Gutshop '81: f i s h food hab i t ciency o f j u v e n i l e EnglCsh sole, studies. Washington Sea Grant Pub1 . (Parophrys vetu l us). Pages 97-1 05 WSG-WO-82-2.

50272 -101

IS. Supplemantary Notes

* U.S. Army Corps o f Engineers TR EL-82-4 16. Abstna (Limit 200 words)

. 1 - I

4. Title end Subtitle

Species P r o f i 1 es: L i f e H i s t o r i e s and Environmental Requirements o f Coastal Fishes and I n v e r t e b r a t e s ( P a c i f i c Northwest) -- Engl i s h So le

7. Author(J

Dennis R. Lassuy 9. Performin# Oraenizatlon Name and Address

Oregon Cooperat ive F i she ry Research U n i t Oregon S t a t e U n i v e r s i t y , 104 Nash H a l l Co rva l l i s , OR 97331-3803 -- -- 12. Sponsorin# Organization Name and Address

Species p r o f i l e s a re l i t e r a t u r e summaries o f t h e taxonomy, morphology, d i s t r i b u t i o n , l i f e h i s t o r y , e c o l o g i c a l r o l e , and environmental requirements o f coas ta l aqua t i c species. Thej a re prepared t o a s s i s t coas ta l managers, engineers, and b i o l o g i s t s i n t h e ga the r ing o f i n f o r m a t i o n p e r t i n e n t t o coas ta l development a c t i v i t i e s . The Eng l i sh s o l e i s a major c o n t r i b u t o r t o P a c i f i c Northwest t r a w l f i s h e r i e s and i s used e x t e n s i v e l y i n t h e f i l e t - o f - s o l e t rade . Spawning i s u s u a l l y most i n t e n s e d u r i n g w i n t e r , b u t occurs i n a l l seasons. Temperature c o n d i t i o n s b e f o r e spawning and d u r i n g t h e egg and l a r v a l stages a r e c r i t i c a l t o subsequent yea r -c lass s t reng th . Hatch ing success i s apparen t l y g r e a t e s t a t s a l i n i t i e c and temperatures o f 25-28 pp t and 8-9 O C . Pos t l a rvae s e t t l e i n open-coast and e s t u a r i n e areas. D e n s i t i e s o f r e a r i n g j r r ven i l es are h i g h e s t i n lower e s t u a r i e s . Growth may be i n h i b i t e d a t temperatures above 17.5 O C . Emigra t ion f rom nu rse ry areas t o deeper, sand- bottomed o f f s h o r e areas occurs d u r i n g l a t e summer and f a l l . Juven i l es and a d u l t s f eed on a wide v a r i e t y o f b e n t h i c i n v e r t e b r a t e s . Female E n g l i s h s o l e grow f a s t e r and mature l a t e r (3-4 yea rs ) than males (2-3 yea rs ) . Females a r e more s u s c e p t i b l e t o cap tu re i n t h e m u l t i - species t r a w l f i s h e r i e s t h a t t y p i f y P a c i f i c Northwest ground f i s h i n g . A b e t t e r under- s tand ing o f t h e r e l a t i o n between oceanic c o n d i t i o n s and e a r l y l i f e - h i s t o r y stages, t h e avoidance o f e s t u a r i n e thermal p o l l u t i o n , and t h e p r o t e c t i o n o f remain ing c o a s t a l n u r s e r y areas a r e impor tan t t o t h e maintenance o f Eng l i sh s o l e abundance.

3. Recipient's Liccaulon NO.

5. Rewtt Date

July 1989

8. Performine Oraanizatlon Rapt. NO

10. ProieetlTasklWork Unit No.

11. bntmct(C) or Cnnt(C) NO.

(c)

(C)

17. Document Analpis a. Deuripmn PI

2. REPORT DOCUMENTATION PAGE

U.S. Department o f t h e I n t e r i o r U.S. Army Corps o f Engineers F i s h and W i l d l i f e Se rv i ce Waterways Experiment S t a t i o n Na t iona l Wetlands Research Center P.O. Box 631 Washington, DC 20240 Vicksburg, MS 39180

Es tua r ies Temperature L i f e c y c l e s F l a t f i s h e s Depth Growth F i s h e r i e s Sediments Oxygen S a l i n i t y Feeding h a b i t s Animal m i g r a t i o n s

1. RE*RT NO.

B i o l o s i c a l Fkpor t 82(11.101)*

I E n q l i s h So le I I parophrys v e t u l u s

Environmental requirements

(Formerly N T I S 3 H *attnrmt of cornmere*

c. COSATI flddlCroup

21. No. ol hems

17 22 Price

18. Avellebility Statment

Unl i m i t e d re lease

(See ANSI-239.18) OWIONIL FORM 272 (677)

19. Security Class flhls Repott)

U n c l a s s i f i e d 20. Security C I a u m i s Pam)

U n c l a s s i f i e d

As the Nation's principal conservation agency, the Department of the Interior has responsibility for most of our nationally owned public lands and natural resources. This includes fostering the wisest use of our land and water resources, protecting our fish and wildlife, preserving the environmental and cultural values of our national parks and historical places, and providing for the enjoy- ment of life through outdoor recreation. The Department assesses our energy and mineral resources and works to assure that their development is in the best interests of all our people. The Depart- ment also has a major responsibility for American Indian reservation communities and for people who live in island territories under U.S. administration.

U.S. DEPARTMENT OF THE INTERIOR FlSH AND WILDLIFE SERVICE

TAKE PRIDE in America

UNITED STATES DEPARTMENT OF THE INTERIOR

FISH AND WILDLIFE SERVICE National Wetlands Research Center

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