Habitat and Nursery Grounds ofPacific Rockfish, Sebastes spp., in RockyCoastal Areas of Southeastern Alaska

H. Richard Carlson and Richard R. Straty arewith the Auke Bay Laboratory, Northwest andAlaska Fisheries Center, National MarineFisheries Service, NOAA, P.O. Box ISS, AukeBay, AK 99821.

H. RICHARD CARLSON and RICHARD R. STRATY

Introduction

The location of nursery grounds forjuvenile Pacific ocean perch, Sebastesalutus, and most other rockfishes,Sebastes spp., in the North PacificOcean is poorly known. We have longsuspected that the rocky, untrawlableareas along the rugged coastline ofsoutheastern Alaska were importantnursery grounds for Pacific oceanperch. These rough areas extend off­shore on the continental shelf to adepth of 420 m (230 fathoms) or more.A few thousand juvenile rockfishes,primarily Pacific ocean perch, havebeen trawled nearshore in coastal baysand fiords of southeastern Alaskaover steep slopes and ledges nearrocky areas (Carlson et al. I). Inciden-

'Carlson, H. R., R. E. Haight, and K. J.Krieger. 1977. Species composition and relativeabundance of demersal marine life in waters ofsoutheastern Alaska, 1969-77. Processed rep.,Auke Bay Laboratory, Northwest and AlaskaFisheries Center, NMFS, NOAA, P.O. BoxISS, Auke Bay, AK 99821.

ABSTRACT-During late July 1978 weused a small submarine to explore therugged rocky substrate along the coast ofsoutheastern Alaska to depths of nearly240 m (/30 fathoms). The extensiveboulder fields and pinnacle-studded bot­tom were populated mostly by rockfish,Sebastes spp., ofseveral species and a widerange of sizes. This untrawlable zone is anursery area for rockfish, and denseschools ofthousands ofsmall 6-8 cm (2.5-3inch) red rockfISh were sighted at 90-100 m(49-55 fathom) depths over crevices andcover. Fish were less abundant in similarsurveys of protected waters of a bay andfiord adjacent to the coastal sites.

July 1981,43(7)

tal catches by commercial salmontrollers indicate that echosign overthese areas is composed primarily ofrockfish.

Offshore, beyond most of the rockyareas, Pacific ocean perch and severalother rockfish species were heavily ex­ploited by foreign trawlers (Major andShippen, 1970) before U.S. manage­ment control (in 1977) overcontinental-shelf fisheries within the200-mile limit. Neither foreign catchesnor those of U. S. research vessels con­ducting resource surveys in thesewaters contained any early juvenilestages of Pacific ocean perch or otherrockfish species (Lyubimova, 1965;Paraketsov, 1963; Ronholt 2

).

Pacific ocean perch and other rock­fish species are ovoviviparous (live­bearers) and are believed to releaselarvae in deeper water (Lyubimova,1965; Gunderson, 1971). The plank­tonic larvae are transported to thenearshore waters by ocean currents(Lisovenko, 1964), a characteristic ofthe life history of many marine fishes(May, 1974), e.g., Dover sole, Micro­stomus pacificus; rex sole, Glypto­cephalus zachirus; and petrale sole,Eopsettajordani (pearcy et al., 1977);English (lemon) sole, Parophrysvetulus (Ketchen, 1956); and dark­blotched rockfish, S. crameri; canaryrockfish, S. pinniger; and rosethornrockfish, S. helvomaculatus (Richard­son and Laroche, 1979).

'Ronholt, L. L. 1979. Northwest and AlaskaFisheries Center, NMFS, NOAA, 2725 MontlakeBlvd. East, Seattle, WA 98112. Personal com­mun.

The age that young of most rock­fish species become demersal is notprecisely known. Phillips (1964) cap­tured young-of-the-year darkblotchedrockfish and stripetail rockfish, S.saxicola, at 73-128 m (40-70 fathoms)while trawling for shrimp off north­ern California. Boehlert (1977) foundthat young splitnose rockfish, S.diploproa, move from surface tonear-bottom waters during their firstyear of life in southern California.Some Pacific ocean perch becomedemersal by age 1, and most probablyadopt a demersal existence in thenearshore coastal zone by the end oftheir first summer of life (Carlson andHaight, 1976). Recent evidence sup­ports this idea. Twenty-five young-of­the-year Pacific ocean perch werecaptured in a bottom trawl in earlyOctober 1979 at 55-84 m (30-46fathoms) in two fiords of southernBaranof Island and 28 more in lateOctober 1980 at 73-128 m (40-70fathoms) off northern ChichagofIsland in southeastern Alaska(Carlson'). They ranged from 5 to 8cm (2 to 3 inches) FL (fork length)and had just begun formation of thefirst annulus, marking the end of theirfirst growing season.

The lack of young rockfish in off­shore catches and their occurrence incatches at several nearshore locationsled Carlson and Haight (1976) tohypothesize that the nearshore, rocky­bottom coastal areas and adjacentbays and straits of Alaska are nurseryareas for Pacific ocean perch. AdultPacific ocean perch reside in and

'Carlson, H. R. Evidence for an early demersalexistence of young-of-the-year Pacific oceanperch in southeastern Alaska waters. Unpubl.manuscr. avail. Auke Bay Laboratory, North­west and Alaska Fisheries Center, NMFS,NOAA, P.O. Box ISS, Auke Bay, AK 99821.

13

Figure I.-Sites of surveys of demersal fish communities off southeasternAlaska, July 1978.

powered, carries two persons, and canoperate down to 305 m (167 fathoms)and operates at 1.8-5.5 km/h (1-3knots) for 2-4 hours.

The transects at exposed coastallocations were plotted across unevenbottom located on earlier echo­sounding surveys. These transectswere <=6 km (3.7 miles) long andgenerally ran from shallow to deepwater. We surveyed single transects<=2 km (1.2 miles) long across thesites in Lisianski Strait and PortlockHarbor.

It was almost impossible to adhereto the coastal transects because of theextreme uneveness of the bottom (Fig.3, 4). Navigating steep pinnacles andsheer ledges would have required fre­quent, rapid changes in depth largelybeyond the capabilities of the sub­mersible at its normal cruise speed of

,NORTH )

\'PACIFIC

\ t1t

.~OCEA \

I

{, s\ ,

PORTLOCKHARBOR

'Reference to trade names or commercial firmsdoes not imply endorsement by the NationalMarine Fisheries Service, NOAA.

in this region, could render thesubmersible operation hazardous.Water visibility was outstanding onopen-coast surveys and ranged from10 to 23 m (33 to 75 feet). On thesurveys inside fiords and bays,visibility was much less, being only2-7 m (6-23 feet).

The submersible Nekton Gamma(Fig. 2), chartered from GeneralOceanographics4 of San Diego,Calif., by NOAA's Manned UnderseaScience and Technology Program Of­fice, was made available to theauthors from 21 to 28 July 1978 toconduct surveys beyond scuba depths(>40 m or > 130 feet). The submers­ible is 5 m (16 feet) long, battery-

Methods

The two exposed, rocky-bottomcoastal areas were off Cape Cross onYakobi Island and off Portlock Harboron Chichagof Island in the northernpart of southeastern Alaska (Fig. 1).The two protected areas were approx­imately 3 km (2 miles) inside LisianskiStrait in the Cape Cross vicinity and1.6 km (1 mile) inside Portlock Har­bor near its southern entrance. Thesefour areas were selected as beingrepresentative of the coastal bottomtopography of the northern part ofsoutheastern Alaska after we con­ducted echo-sounding surveys in May1978 in this region.

The areas off Cape Cross andPortlock Harbor were exposed toopen-ocean sea and swell conditions,and the water was much clearer thaninside Lisianski Strait and PortlockHarbor where waters were not as sub­ject to oceanic influence and heavyseas and swells. The greater turbidityof the protected areas may be due tomaterial suspended in the water fromsurface runoff and streams, andrestricted circulation with the adja­cent, clearer offshore waters.

We were fortunate to have unusual­ly good weather during the surveyperiod. Seas off the coast generallyranged from a gentle ocean swell to Im (3 foot) swells, which permittedlaunching and retrieval of the sub­mersible without incident. Moderateto heavy seas, which frequently occur

along gullies and canyons fartherseaward on the outer continental shelf(Major and Shippen, 1970).

In July 1978, we used a smallsubmersible to search for youngPacific ocean perch and visuallysurvey fish in two rocky-bottomcoastal areas exposed to open-seaconditions and in an adjacent bay andstrait protected from open-sea condi­tions in the northern part of south­eastern Alaska. This paper presentsour observations of the behavior andhabitat of young rockfish believed tobe Pacific ocean perch, and describesthe behavior and habitat of severalother species of rockfish at variouslife stages.

14 Marine Fisheries Review

3.7 km/hour (2 knots). After someexperience, we decided to cruise alongthe bottom for short distances andstop frequently to make observationswhen the submersible path was ob­structed by abrupt changes in bottomtopography. We followed transectsacross the center of the two insideprotected sites without difficulty.

We identified in situ the types ofsubstrate and fish species, estimatedtheir sizes and relative abundance,and noted schooling behavior andreaction of fish to the submersible.Descriptions of the fish, theirhabitats, and behavior were recordedon a small portable tape recorder.Fish and their habitats were photo­graphed in color with an externallymounted 35 mm Benthos Model 372camera with flash. The camera wasoperated by the submersible pilot assubjects of interest came into view.We also used a portable video cassettecamera to obtain black-and-white

Figure 2.-The research submarine Nekton Gamma used to survey demersalfish in southeastern Alaska.

Figure 3.-Bottom topography of the survey area as charted seaward from Portlock Harbor.

'is-

Iis-

Figure 4.-Bottom topography of the survey area as charted seaward from Cape Cross.

July 1981, 43(7) 15

Figure 5.-Young rockfish over part of a steep, rocky pinnacle.

Figure 7.-Several rockfishes over part of an extensiveboulder field. A young yelloweye rockfish is in the extremelower right, a tiger rockfish to the right, and small unidenti­fied rockfish to the upper center and upper left.

Figure 6.-Young rockfish and rugged, rocky substrate.

Figure 8.-A large (:>2 m) wolf-eel moves slowly over aboulder field.

documentation of fish and theirbehavior.

Rockfish Nursery Area

Our most significant findings camefrom the surveys offshore from Port­lock Harbor and Cape Cross (Fig. 1).Here we found what appeared to benursery grounds for young rockfish.These schools were at 90-100 m (49-55fathoms), over a bottom that variedfrom ragged, steep, rocky pinnacles(Fig. 5, 6) to extensive boulder fields

16

(Fig. 7, 8) interspersed with areas ofgravel-shell that were deeply furrowed,apparently by wave action.

Marine life in the rocky areas wasabundant and diverse. Rockfish ofseveral species and wide size-rangepredominated. Clouds of thousandsof 6-8 cm (2.5-3 inch) reddish rockfish(Fig. 9), which we believe are Pacificocean perch, extended as far as thelimits of visibility (as much as 18 m or60 feet) in all directions. These smallrockfish were reddish with some

darker blotching above the lateral lineand generally had a slender body pro­file. They had no heavy spines evidentin the head region; no black marginon fins; no distinct stripes, spots, orbars; and no disproportionate featuresuch as large eye, high dorsal fin, etc.Larger Pacific ocean perch have apronounced symphyseal knob or pro­jecting lower jaw, but this is not welldeveloped in the young.

We saw other fishes in the rockyoffshore areas (Table 1). Large

Marine Fisheries Review

Figure 9.-Part of a dense school of young, 6-8 em, red rockfish (believed to beSebastes alutus) that extended to the limits of visibility over a rugged, rockyboulder field.

Figure IO.-A large (I m) lingcod Oeft) and several yelloweye rockfishphotographed over a portion of sand-shell substrate adjacent to rocky zones.Furrows in the sand (upper left) were apparently caused by surge action down to':Xl-IOO m (49-55 fathoms). These rockfish were attracted to the submarine andexamined it closely.

few large Pacific halibut, Hippo­glossus stenolepis; lingcod, Ophiodonelongatus; kelp greenling, Hexagram­mos decagrammus; and wolf-eels,Anarrhichthys ocellatus. Smallyellowtail rockfish, china rockfish,quillback rockfish, and either duskyrockfish, S. ciliatus, or blackrockfish, S. melanops, were observedby scuba divers at 9-18 m (30-60 feet)inshore at Cape Cross (Barr') at thesame time as our observations; there­fore, the nursery area probablyextends into subtidal shallows.

Invertebrates in rocky offshoreareas were not sparse but generallylacked variety. Frequently encoun­tered were anemones, Metridiumsenile (Fig. II); hydrocorals, Alloporasp.; sea stars (i.e., Crossaster pap­posus, Henricia sp., Solaster sp.);basket stars, Gorgonocephalus sp.;brittle stars; sponges; and bryozoans.

The two submersible surveys insidebays and fiords with entrance sillsnear the open coast, in Lisianski Straitand Portlock Harbor, covered depthsof 18-240 m (10-130 fathoms). Wefound steep, rocky ledges that ex­tended from nearshore and were over­laid with sand-shell at shallower depthsand sand-silt at deeper depths. Atdeeper depths, we found a fewisolated boulders and smooth rockyoutcrops. At the inside sites, rockfishwere not as abundant and fewer spe­cies were sighted. Most of the fish weretypes that lay in contact with thesubstrate, such as flatfish, skates,sculpins, and poachers. The onlyrockfishes sighted were a school ofmixed large and small dusky rockfishin 18 m (10 fathom) shallows andisolated large individual rougheyerockfish, quillback rockfish, andPacific ocean perch at deeper levels,:>183 m (l00 fathoms). We also saw afew large Pacific cod, Gadus macro­cephalus, and large and small walleyepollock, Theragra chalcogramma.

Invertebrates were abundant anddiverse at inside sites. Below 91 m (50fathoms), pink shrimp, Pandalus

'Barr, L. P.O. Box 361, Auke Bay, AI( 99821.Personal commun.

maliger; rosethorn rockfish; widowrockfish, S. entomelas; rougheyerockfish, S. aleutianus; tiger rockfish,S. nigrocinctus; and silvergrayrockfish, S. brevispinis; as well as a

yelloweye rockfish, S. ruberrimus(Fig. 10), were abundant. Also pres­ent were yellowtail rockfish, S.flavidus; china rockfish, S.nebulosus; quillback rockfish, S.

July /981, 43(7) 17

Table 1.-Fishes observed during submersible surveys off the northwestern coast of Chichagof Island, Alaska, July 1978.

Figure I I.-Large white anemones, Metridium senile, growing on boulders,provide shelter for small rockfish, Sebastes sp.

Common name

Rougheye rock fishPacific ocean perchSilvergray rockfishDusky rockfishWidow rockfishYellowtail rockfishRosethorn rockfishQuillback rockfishChina rockfishTiger rockfishYelloweye rockfishWolf-eelLingcodKelp greenlingSearcherPacific cod

SCientific name

Sebastes aleutianusSebastes alutusSebastes brevispimsSebastes ciliatusSebastes enlomelasSebastes /lavidusSebastes helvomaculatusSebastes maligerSebastes nebulosusSebastes nigrocinctusSebastes ruberrimusAnarrhichlhys aeellatusOphiodon etongatusHexagrammos decagrammusBathymaster signatusGadus macrocephalus

Common name

Walleye pollockPacific halibutFlathead soleEnglish soleDover saleBig skateLongnose skateUnidentified sculpInBlackfin sculpinSturgeon poacherBlackfin poacherAlaska eelpoutCoho salmonPacific sand lanceRatfish

Scientific name

Theragra chalcogrammaHippoglossus stenolepisHippoglossoides elassodonParophrys vetulusMicrostomus pacilicusRaja binoculataRaja rhinaTrig/ops sp.Malacocottus kincaidlAgonus acipenserinusBathyagonus nigripinnisBothrocara pus iliumOncorhynchus kisutchAmmodytes hexapterusHydrolagus colliei

range and swam off. Large halibutappeared curious but cautious andcould not be approached closely,Schools of rockfish other than yellow­eye rockfish appeared to behave nor­mally and paid no particular notice tothe submersible, unless we moveddirectly towards a school and thenthey moved off.

Conclusions

The rocky areas, exposed to open­sea conditions, that we surveyed are ahaven or nursery ground for youngrockfishes including Pacific oceanperch. This finding supports thehypothesis by Carlson and Haight(1976) that juvenile Pacific oceanperch inhabit these areas where coverand protection are afforded by cracksand crevices in and under rocks andledges and among sessile invertebratessuch as the anemone Metridium senile.

Near-bottom marine life differed inthe two types of areas surveyed. In theexposed outer coastal areas, fishespredominated, primarily rockfishes ofseveral species and life stages. In con­trast, in the protected waters of anadjacent coastal fiord and bay, inver­tebrates predominated, primarilyshrimp, small crabs, snails, sea stars,and anemones. Many species of inver­tebrates and most life stages wererepresented; fish were few in numberand variety.

Literature Cited

borealis, were particularly abundant,and at least four other species ofshrimp were seen, including sidestripeshrimp, Pandalopsis dispar. Octopus,nudibranchs, and gastropods werecommon, as were sea stars and ane­mones. Many small snow crabs,Chionoecetes sp., 1-4 cm (0.5-1.5inches), were seen in or near thedeepest part of Lisianski Strait at227-238 m (124-130 fathoms).

Reaction ofFishes to Submersible

Most rockfish did not appear

18

frightened by or attracted to thesubmersible with its lights and strobesthat flashed intermittently. Notableexceptions were large yelloweye rock­fish, which appeared to be attractedto the submarine and actually followedit around and cruised in close to peerin portholes. They appeared intriguedwith the submersible. In one instancehundreds of these large, reddish, 7-10kg (15-22 pound) fish trailed behindthe submersible in a long column.

Large wolf-eels usually movedslowly away and appeared to beat adignified retreat. Large lingcod brieflylooked the submersible over at close

Boehlert, G. W. 1977. Timing of the surface­to-benthic migration in juvenile rockfish,Sebastes diploproa, off southern California.Fish. BuU., U.S. 75:887-890.

Carlson, H. R., and R. E. Haight. 1976. Juve­nile life of Pacific ocean perch, Sebastesalutus. in coastal fiords of southeasternAlaska: Their environment, growth, foodhabits, and schooling behavior. Trans. Am.Fish. Soc. 105:191-201.

Gunderson, D. R. 1971. Reproductive patternsof Paci fic ocean perch (Sebastodes alutus) offWashington and British Columbia and theirrelation to bathymetric distribution andseasonal abW1dance. J. Fish. Res. BoardCan. 28:417-425.

Ketchen, K. S. 1956. Factors influencing thesurvival of the lemon sole (Parophrys vetulus)in Hecate Strait, British Columbia. J. Fish.Res. Board Can. 13:647-693.

Lisovenko, L. A. 1964. Distribution of Far­eastern redfish Sebastodes alutus Gilbert inthe Gulf of Alaska. [In Russ.] Tr. Vses.Nauchno-issled. lnst. Morsk. Rybn. Khoz.

Marine Fisheries Review

Okeanogr. 53 (Izv. Tikhookean. Nauchno­issled. Inst. Morsk. Rybn. Khoz. Okeanogr.52:223-231. (Trans!. by Isr. Prog. Sci.Trans!., 1%8. In P. A. Moiseev (editor),Soviet fisheries investigations in the north­eastern part of the Pacific Ocean, Part 3, p.217-225. Avail. Nat!. Tech. Inf. Serv., Spring­field, VA 22151, as IT 67-51205.)

Lyubimova, T. G. 1%5. The main stages in thelife cycle of Pacific ocean perch Sebaslesalulus Gilbert in the Gulf of Alaska. [InRuss.] Tr. Vses. Nauchno-iss1ed. Inst. Morsk.Rybn. Khoz. Okeanogr. 58 (izv. Tikhookean.Nauchno-issled. Inst. Morsk. Rybn. Khoz.Okeanogr. 53 :95-120). (Trans!. by Isr. Prog.Sci. Trans!., 1%8. In P. A. Moiseev (editor),Soviet fisheries investigations in the north­eastern part of the Pacific Ocean, Part 4, p.

July 1981,43(7)

85-111. Avail. Nat!. Tech. Inf. Serv., Spring­field, VA 22151, as IT 67-51206.)

Major, R. L., and H. H. Shippen. 1970. Synop­sis of biological data on Pacific ocean perch,Sebaslodes alulus. U.S. Dep. Commer., Nat!.Mar. Fish. Serv., Circ. 347, 38 p.

May, R. C. 1974. Larval mortality in marinefishes and the critical period concept. In J. H.S. Blaxter (editor), The early life history offish, p. 3-19. Springer-Verlag, N. Y.

Paraketsov, I. A. 1963. On the biology ofSebaslodes alulus in the Bering Sea. [InRuss.] Tr. Vses. Nauchno-issled. Inst. Morsk.Rybn. Khoz. Okeanogr. 48 (Izv. Tikhookean.Nauchno-issled. Inst. Morsk. Rybn. Khoz.Okeanogr. 50:305-312). (Trans!. by Isr. Prog.Sci. Trans!., 1968. In P. A. Moiseev (editor),Soviet fisheries investigations in the north-

eastern part of the Pacific Ocean, Part I, p.319-327. Avai!. Nat!. Tech.lnf. Serv., Spring­field, VA 22151, as IT 67-51203.)

Pearcy, W. G., M. J. Hosie, and S. L. Richardson.1977. Distribution and duration of pelagic lifeof larvae of Dover sole, Microslomus paciji­cus; rex sole, G/yplocephalus zachirus; andpetrale sole, Eopsella jordani, in waters offOregon. Fish. Bull., U.S. 75:173-183.

Phillips, J. B. 1964. Li fe history studies on tenspecies of rockfish (Genus Sebaslodes). Calif.Dep. Fish Game Fish Bull. 126, 70 p.

Richardson, S. L., and W. A. Laroche. 1979.Development and occurrence of larvae andjuveniles of the rockfishes Sebasles crameri,Sebasles pinniger, and Sebastes helvo­maculatus (Family Scorpaenidae) offOregon. Fish. Bull., U.S. 77:1-46.

19