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T I I . H i s t o l o g i c a l c r i t e r i a u s e d t o d e t e r m i n e r e p r o d u c t i v e s t a g e i n H

. d . d a c t y l o p t e r u s ( W a l l a c e & S e l m a n 1 9 8 1 ; H u n t e r & M a c e w i c z

1 9 8 5 ; W e n n e r e t a l . ,

1 9 8 6 )

R e p r o d u c t i v e s t a g e

M a l e

F e m a l e

U n c e r t a i n m a t u r i t y I n a c t i v e t e s t e s ; r e s t i n g o r i m m a t u r e

I n a c t i v e o v a r i e s ; p r e v i t e l l o g e n i c o o c y t e s o n l y ; i m m a t u r e o r

r e s t i n g

I m m a t u r e ( v i r g i n )

S m a l l t r a n s v e r s e s e c t i o n c o m p a r e d t o

r e s t i n g m a l e ; s p e r m a t o g o n i a a n d l i t t l e o r

n o s p e r m a t o c y t e d e v e l o p m e n t ; l o b u l e s a n d

s p e r m a t i c d u c t n o t a s e v i d e n t a s i n r e s t i n g

s t a g e

P r e v i t e l l o g e n i c o o c y t e s o n l y , n o e v i d e n c e o f a t r e s i a . I n c o m

p a r i s o n t o

r e s t i n g f e m a l e , m o s t p r e v i t e l l o g e n i c o o c y t e s < 7 0

m i n d i a m e t e r , a

r e a

o f t r a n s v e r s e s e c t i o n o f o v a r y i s s m a l l e r , l a m e l l a e l a c k m u s c l e a n d

c o n n e c t i v e t i s s u e b u n d l e s a n d

a r e n o t a s e l o n g a t e

, g e r m i n a l e p i t h e l i u m

a l o n g m a r g i n o f l a m e l l a e i s t h i c k e r , a

n d o v a r i a n w a l l i s t h i n n e r

D e v e l o p i n g

D e v e l o p m e n t o f

c y s t s c o n t a i n i n g p r i m a r y

a n d s e c o n d a r y s p e r m a t o c y t e s t h r o u g h s o m e

a c c u m u l a t i o n o f s p e r m a t o z o a i n l o b u l a r

l u m i n a a n d d u c t s

S e e b e l o w

S p a w n i n g

P r e d o m i n a n c e o f s p e r m a t o z o a i n l o b u l e s ;

s p e r m a t o z o a a b u n d a n t i n s p e r m a t i c d u c t ;

l i t t l e o r n o o c c u r r e n c e o f s p e r m a t o g e n e s i s

C o m p l e t i o n o f y o l k c o a l e s c e n c e a n d h y d r a t i o n i n m o s t a d v a n c e d

o o c y t e s ; z o n a r a d i a t a b e c o m e s t h i n n e r ; e a r l y - c e l l e d e m b r y o s p r e s e n t

S p e n t

N o s p e r m a t o g e n e s i s ; s o m e r e s i d u a l

s p e r m a t o z o a i n l o b u l e s a n d s p e r m a t i c d u c t

M o r e t h a n 5 0 % o f v i t e l l o g e n i c o o c y t e s w i t h a l p h a - o r b e t a - s

t a g e

a t r e s i a

R e s t i n g

L a r g e t r a n s v e r s e s e c t i o n c o m p a r e d t o

i m m a t u r e m a l e ; l i t t l e o r n o s p e r m a t o c y t e

d e v e l o p m e n t ; r e s i d u a l s p e r m a t o z o a i n

d u c t s , t h o u g h l e s s t h a n i n s p e n t s t a g e

P r e v i t e l l o g e n i c o o c y t e s o n l y w i t h t r a c e s o f a t r e s i a p o s s i b l e

. I n

c o m p a r i s o n t o i m m a t u r e f e m a l e , m o s t p r e v i t e l l o g e n i c o o c y t e s > 7 0

m ,

a r e a o f t r a n s v e r s e s e c t i o n o f o v a r y i s l a r g e r , l

a m e l l a e h a v e m u s c l e a n d

c o n n e c t i v e t i s s u e b u n d l e s , l a m

e l l a e a r e m o r e e l o n g a t e a n d c o n v o l u t e d ,

g e r m i n a l e p i t h e l i u m a l o n g m a r g i n o f l a m e l l a e i s t h i n n e r , o v a r i a n w a l l

i s t h i c k e r

E a r l y d e v e l o p i n g ,

c o r t i c a l a l v e o l i

M o s t a d v a n c e d o o c y t e s i n c o r t i c a l - a

l v e o l i s t a g e

D e v e l o p i n g ,

v i t e l l o g e n e s i s

M o s t a d v a n c e d o o c y t e s i n y o l k - g r a n u l e o r y o l k - g

l o b u l e s t a g e

F i n a l o o c y t e

m a t u r a t i o n

M o s t a d v a n c e d o o c y t e s i n m i g r a t o r y - n u c l e u s s t a g e ; p a r t i a l c o a l e s c e n c e

o f y o l k g l o b u l e s p o s s i b l e

D e v e l o p i n g ,

r e c e n t s p a w n

P r e s e n c e o f p o s t o v u l a t o r y f o l l i c l e s a n d v i t e l l o g e n i c o o c y t e s

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oocyte development at or beyond the cortical granule (alveoli) stage and specimens withbeta, gamma, or delta stages ( Hunter & Macewicz, 1985 ) of atresia. To ensure thatfemales were assigned correctly to the immature and resting categories, the lengthfrequency histograms of females with evidence of certain maturity (developing, ripe, orspent) and resting females were compared.

To estimate the sex ratio in the population, the data were restricted to collections thatrepresented random sampling; collections in which females were sampled selectively forthe study of reproductive biology were eliminated. The 2 goodness-of-t test (Zar,1984 ), with Yates correction for continuity, was used to compare the sex ratio ineach 25-mm length interval with a hypothetical 1 : 1 ratio. The result was considered

signicant if P 25years, the mean length at age appeared to decrease ( Fig. 6 ); however, the samplesize of sh >25 years was small ( n=19). The mean length of all females wassignicantly less (12 mm) than the mean length of all males [ t =5037, P< 000001,d.f.=1125 ( Fig. 7 )]; however the mean length of females was signicantlyless than the mean length of males only for age classes 9, 13, 14, 16, 18, and 26(Table III ). We were unable to t the von Bertalan ff y growth equation, or anyother growth function, to our mean length at age data.

No conclusively immature specimens were collected. Two of the 748 malesexamined, 14 years/256 mm and 15 years/275 mm, were either immature orresting [ Fig. 8(a) ]. There was no evidence of spermatogenesis and residualspermatozoa were not present in lobular lumina and ducts [Fig. 9(a) ], indicating

Dec

0.45

0.15Dec

Month

S t a n

d a r d

i z e d m a r g i n a l

i n c r e m e n

t

Apr

0.40

0.35

0.30

0.25

0.20

Feb Jun Aug Oct

F . 3. Marginal increment ( 1 . .) by month for H. d. dactylopterus captured o ff the Carolinas. n=294.

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that these specimens had not spawned previously. In mature males includingmost resting-stage males, spermatozoa were present throughout the year inlobular lumina and the stalk-like system of ducts [Fig. 9(b) ]. Nine of the 445females examined were either immature or resting [Fig. 8(b) ]. Their ages andsizes ranged from 10 to 15 years and 215289 mm. For both sexes, the generaloverlap in the lengthfrequency histograms for resting specimens and specimenswith evidence of certain maturity indicated that males and females were assignedaccurately to immature and resting stages.

The reproductive mode appeared to be intermediate between oviparity andviviparity. Histological sections contained evidence of internal fertilization, asfree spermatozoa [Fig. 10(a) ] were observed in resting or developing ovariesbetween July and early December, with peak occurrence between September andNovember (Table IV ). This peak corresponded to the spawning peak noted for

450

140

0100

Total length (mm)

F r e q u e n c y

350

100

120

80

60

40

20

150 200 250 300 400

F . 4. Lengthfrequency distribution of H. d. dactylopterus captured o ff the Carolinas. n=1309;

mean=29559.

40

160

05

Age (years)

F r e q u e n c y

30

100

120

80

6040

20

10 15 20 25 35

140

F . 5. Agefrequency distribution of H. d. dactylopterus captured o ff the Carolinas. n=1135;mean=1597.

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35

380

2605

Age (years)

M e a n

l e n g t

h ( m m

L T

)

20

320

360

340

300

280

10 15 25 30

F . 6. Mean observed growth curves ( 1 . .) of male ( , n=639) and female ( , n=405) H. d.dactylopterus captured o ff the Carolinas.

450

60

0150

Total length (mm)350

50

40

30

20

10

200 250 300 400

(b)

450

100

0150

F r e q u e n c y

350

80

60

40

20

200 250 300 400

(a)

F . 7. Lengthfrequency histograms for male (a) and female (b) H. d. dactylopterus sampled randomly.

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males [ Fig. 11(a) ]. Spermatogenesis occurred in males during all months andresting individuals were common only between January and March.

There was a delay between insemination and fertilization, as oocyte develop-ment did not begin until December, which was after the peak occurrence of freespermatozoa in ovaries [Fig. 11(b) ]. Seventy-seven per cent of the 116 femaleswith free spermatozoa were in the resting stage. After insemination, spermato-zoa were stored until fertilization in crypts that formed near the bases of lamellae. These crypts were often adjacent to blood vessels [ Fig. 10(b) ]. Theabrupt appearance of yolk globule-stage oocytes in early December and thesubsequent short (

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Capillaries in the stalk [ Fig. 12(b) ] provide blood ow to an individual oocyteand the stalk functions to place the oocyte into the ovarian cavity and near theovary wall, where a clear gelatinous matrix envelops the eggs after ovulation andfertilization.

Eggs developed within the gelatinous matrix into early-celled embryoscomposed of an undi ff erentiated mass of cells approaching the blastula stageand a large yolk mass [Fig. 12(c) ]. At parturition, the embryos are extrudedpresumably in the gelatinous matrix. Based on the percentage frequencies of spawning-stage individuals and postovulatory follicles, female roseshspawned between December and April, with a peak in February and March[Fig. 11(b) ].

The population sex ratio departed markedly from 1 : 1 for most lengthintervals ( Table V ). The overall ratio was 1 7 : 0608 . At lengths c 250 mm, theratio was not signicantly di ff erent from 1 : 1, whereas males were moreabundant at lengths >250 mm. Females were most abundant during September(17 : 1038), October (1 7 : 0838), and November (1 7 : 1038), which corre-sponded to the spawning peak for males.

450

50

0150

Total length (mm)

N u m

b e r

350

40

30

20

10

200 250 300 400

(b)

500

160

0150 350

80

60

40

20

200 250 300 400

(a)

450

100

120

140

F . 8. A comparison of length-frequencies for 748 male (a) and 445 female (b) specimens of H. d.dactylopterus categorized as uncertain maturity (immature or resting ), denitely mature ( ), andresting ( ). Specimens categorized as denitely mature were developing, spawning, or spent.

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DISCUSSION

Growth of blackbelly rosesh described here is that of mature males andfemales. Our samples contained no specimens ages 06 years, and therefore o ff erlittle insight into the life history of the juvenile stage. The relatively slow growthof mature sh cannot be extrapolated to young (ages 06) sh.

Withell & Wankowski (1988) reported an age range of 242 years for H. percoides , which is similar to H. d. dactylopterus ages (730 years) found in thisstudy. Esteves et al . (1997) , reading whole otoliths from specimens of a similarsize, found H. d. dactylopterus from the Azores to be age 314 years but the agesare possibly underestimated because reading whole otoliths is inaccurate forlong-lived species ( Beamish & McFarlane, 1987 ; Maceina & Betsill, 1987 ).

The absence of younger age classes (06) in this study suggests that H. d.dactylopterus is not recruited into the commercial deep-water longline sheryuntil c. age 7. Juvenile H. d. dactylopterus are present in the deep-water shcommunity as they have been observed, via submersible, to occupy tileshburrows (C. Grimes, National Oceanic Atmospheric Administration/National

F . 9. Transverse sections of testes in (a) immature (275 mm L T , bar=100 m) and (b) late developing(280 mm L T , bar=400 m) H. d. dactylopterus . d, Eff erent ducts.

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Marine Fisheries Service, pers. comm.). The decrease in size-at-age after age 25is possibly a result of small sample sizes for these older age classes, althoughPearson et al . (1991) reported a similar decrease in size-at-age for female Sebastes jordani (Gilbert). Marginal increment formation suggests that somatic growth of blackbelly rosesh is primarily between March and May, which substantiatestheir slow growth and small size.

The ndings of Kelly et al . (unpublished) that male blackbelly rosesh matureat 1115 years (260 mm), and females at 1419 years (230 mm) o ff the coast of Ireland, supports our preliminary ndings that males and females maturepotentially at 1415 years (256275 mm) and 1015 years (215289 mm) respect-ively. Additional juvenile and small adult specimens are needed to dene sizeand age at maturity conclusively.

Blackbelly rosesh exhibit an atypical reproductive mode for teleosts, as theyhave internal fertilization and intraovarian gestation ( Kre ff t, 1961 ; Sanchez &Acha, 1988 ). This mode of reproduction is found in only two teleost families, theScorpaenidae and Zoarcidae (Wourms et al ., 1988 ). Internal fertilization is the

F . 10. Transverse sections of (a) free spermatozoa in a resting female H. d. dactylopterus captured inOctober and (b) crypt of spermatozoa in a developing female H. d. dactylopterus captured in earlyDecember (bar=10 m).

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rule in the subfamily Sebastinae ( Boehlert & Yamada, 1991 ), which is composedof the genera Hozukius , Helicolenus , Sebastiscus , and Sebastes . In the presentstudy, the period of gestation was probably 2030 days, as yolk globule-stageoocytes were present in early December and embryos were noted in late January.This estimate seems reasonable because species of Sebastes that release larvaeat parturition (viviparity) have gestation periods of 3060 days ( Moser, 1967 ;Bowers, 1992 ; Nichol & Pikitch, 1994 ). Reproductive mode in Helicolenusranges from a zygoparous form of oviparity, characteristic of H. d. dactylopterus ,to viviparity (release of full-term embryos) in H. percoides (Wourms, 1991 ).

A notable feature, previously undescribed, of the reproductive mode in H . d.dactylopterus is the delay of c. 13 months between insemination and fertiliz-ation. Delays of 15 months have been reported in species of Sebastes off Japan(Takahashi et al ., 1991 ). Details of the mechanism by which spermatozoaremain viable in ovaries until oocytes have developed are still not known,particularly for species of Sebastes that lack structures for sperm storage(Takahashi et al ., 1991 ). Sorokin (1961) proposed that spermatozoa in the ovaryof S. marinus (L.) are stored in a state of physiological rest during the monthsprior to fertilization and at the appropriate time are activated by changes in thepH of ovarian uid. The crypts of spermatozoa [ Fig. 10(b) ] that we observed infemale blackbelly rosesh appear to be a structure for sperm storage. The samestructure was noted at the base of ovarian lamellae in H. lengerichi (Norman)from the Pacic coast of South America ( Lisovenko, 1979 ). Spermatozoa wereobserved within the ovarian stroma of S. crameri (Jordan) by Nichol & Pikitch(1994) , although no storage structure was described.

The reproductive mode and spawning season of H . d. dactylopterus off thesouth-east coast of the United States is similar to that found in other locations.Male spermatozoa production peaked in the fall (SeptemberNovember), andfemale rosesh spawn during the winter and early spring (DecemberApril). O ff the Azores, the spawning peak in male H . d. dactylopterus occurs in September,

T IV. Occurrence of free spermatozoa inthe ovaries of 534 H. d. dactylopterus

Month Numberexamined% with

spermatozoa

January 39 00February 50 20March 82 00April 55 00May 41 00June 15 00July 26 115August 24 125September 37 649October 65 631

November 52 712December 48 146

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and female H . d. dactylopterus are reported to spawn in JanuaryApril (Isidro,1987 , in Esteves et al ., 1997 ). The subspecies of H . dactylopterus found o ff Argentina, Uruguay, and southern Brazil ( H. d. lahillei ) also spawns during thewinter and early spring, as Sanchez & Acha (1988) reported the capture of eggsat the stage of tail bud formation in September plankton samples and femaleswith early-celled embryos (pre-cleavage) in a clear gelatinous matrix in trawlcollections 2 months later.

F . 11. Reproductive seasonality of male (a) and female (b) H. d. dactylopterus based on histologicalcriteria. Number of specimens examined by month is above each bar. , Developing; ,migrating nucleus; , spawning; , postovulatory follicles; , spent; , resting.

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F . 12. Transverse sections of oocytes and embryos in H. d. dactylopterus . (a) Yolk globule-stageoocytes are suspended on stalks that radiate from lamellae (bar=100 m). (b) Blood ows to anoocyte through capillaries in the stalk (bar=25 m). (c) Early-celled embryo imbedded in the cleargelatinous matrix found in the ovarian cavity (bar=50 m). w, Ovary wall.

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The presence of early-celled embryos in a gelatinous matrix was also observedby Kre ff t (1961) in H. d. dactylopterus from the northeast Atlantic. Thisgelatinous matrix is characteristic of Helicolenus (Wourms, 1991 ) and also occursin some species of Scorpaena (Orton, 1955 ) and Sebastes (Wourms, 1991 ).Wourms (1991) proposes that the matrix enhances embryo survival by repellingpotential predators. Although H. dactylopterus has been considered viviparousby some investigators ( Kre ff t, 1961 ), full-term embryos have not been observedin the gelatinous matrix. This inconsistency is probably the result of di ff ering

denitions of viviparity. In the present study, we have accepted the denitionpresented by Wourms (1991) .

The present study found that male H. d. dactylopterus grew signicantly fasterand were more abundant than females. Golovan et al . (1991) reported that maleH. lengerichi were more abundant than females. Although our results could berelated to commercial gear bias, the data of Golovan et al . (1991) were collectedindependent of a commercial shery, via trawl.

Our ndings are consistent with those of other investigations of scorpaenid lifehistory ( Echeverria, 1987 ; Withell & Wankowski, 1988 ; Golovan et al ., 1991 ;Pearson et al ., 1991 ). Helicolenus d. dactylopterus is slow growing and long-lived.

This implies that the natural mortality rate is almost certainly low. The relativelyslow growth of this species may limit further expansion in the United Statesshery given that slow growing sh are easily overexploited. This slow growthmakes the usefulness of an agelength key extremely limited. Although H . d.dactylopterus was not commercially landed until 1989, it has been captured o ff the Carolinas as bycatch since the bottom longline shery began c. 19811982(Low & Ulrich, 1983 ). Although current shing pressure is low, even low levelsof shing may result in signicant harvest of the sustainable yield of H . d.dactylopterus . The shery for H . d. dactylopterus may need to be reassessed if shing pressure increases.

We thank K. Grimball and D. Schlegel for preparing histological sections; the lateCaptain J. Dickie Skipper, III, of Southport, NC, whose cooperation greatly expeditedthis research; and D. Codella for collecting samples. This research was supported by the

T V. Sex ratio of H. d. dactylopterus by 25-mm L T intervals and2 values of tests for

a 1 : 1 ratio

L T Male Female 7 : 82

201225 6 16 1 : 267 368226250 40 48 1 : 120 056251275 127 87 1 : 068 711*276300 176 105 1 : 060 1744301325 170 87 1 : 051 2616326350 99 53 1 : 054 1332351375 61 26 1 : 043 1329376400 21 2 1 : 010 1024*401425 3 0Total 703 424 1 : 060 6857

*P

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National Marine Fisheries Service (South Carolina MARMAP contract No.52WCNF6006013PW). This is Contribution No. 410 from the South Carolina MarineResources Center.

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Boehlert, G. W. & Yamada, J. (1991). Introduction to the symposium on rockshes.Environmental Biology of Fishes 30, 913.

Bowers, M. J. (1992). Annual reproductive cycle of oocytes and embryos of yellowtailrocksh Sebastes avidus (Family Scorpaenidae). Fishery Bulletin 90, 231242.

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