597

North American Journal of Fisheries Management 20:597–609, 2000q Copyright by the American Fisheries Society 2000

Techniques for Tagging and Tracking Deepwater Rockfishes

RICHARD M. STARR*University of California Sea Grant Extension Program,

Post Office Box 440, Moss Landing, California 95039, USA

JOHN N. HEINE AND KORIE A. JOHNSON1

Moss Landing Marine Laboratories,Post Office Box 450, Moss Landing, California 95039, USA

Abstract.—Using scuba in August and September 1997 and 1998, we surgically implanted acous-tic transmitters (Vemco V16 series) in 6 greenspotted rockfish Sebastes chlorostictus and 16 bo-caccio S. paucispinis on the flank of Soquel Canyon in Monterey Bay, California. In 1997 we usedlongline gear to capture and tag greenspotted rockfish, and in 1998 we worked with a commercialfisherman who used modified trolling gear to help us capture and tag bocaccio. Each year, fishwere captured at depths of 100–200 m and reeled up to a depth of approximately 20 m. This depthwas chosen to reduce temperature and pressure stress caused by bringing fish to the surface. Ateam of scuba divers descended to the 20-m depth and anesthetized and surgically implantedacoustic transmitters in both species of rockfish. Tagged fish were released on the bottom at thelocation of catch. Several weeks after tagging, we used the Delta submersible to place an arrayof recording receivers on the seafloor, which enabled tracking of horizontal and vertical movementsof tagged fish for a 3-month period. In September 1998, scientists and pilots were able to relocatethree of the tagged fish by using a hydrophone on the submersible, which enabled them to navigateto the middle of schools that contained the tagged fish. Tagged fish were tracked for a 3-monthperiod and provided information about the movements of the two species.

Rockfishes Sebastes spp. are an important com-ponent of the commercial and recreational fisherieson the U.S. West Coast. Fishing effort and landingsof rockfishes have increased significantly over thelast 40 years (Pearson and Ralston 1990), and thereare now indications that abundance and size com-position for several species are decreasing (Pear-son and Ralston 1990; Karpov et al. 1995; PacificFishery Management Council 1995; Ralston1998). As a result, fishery management for rock-fishes is becoming increasingly complex, and area-specific management strategies, such as the use ofmarine reserves, are being considered as a way toconserve stocks (Yoklavich 1998). The effective-ness of spatial management techniques, however,is dependent upon the rates of movement of theprotected species. Because knowledge about fishmovements is important to evaluate the efficacy ofarea management strategies, we developed tech-niques to tag and track rockfishes inhabiting waterdepths of 100–200 m, which we define for thisstudy as deep water.

* Corresponding author: starr@mlml.calstate.edu1 Present address: National Marine Fisheries Service,

501 West Ocean Boulevard, Suite 4200, Long Beach,California 90802, USA.

Received July 19, 1999; accepted January 16, 2000

In traditional tag–recapture studies, fish arebrought to the surface, tagged with an externalmarker, and released. Researchers then wait for tagrecoveries via the commercial or recreational fish-ery (e.g. Mathews and Barker 1983; Culver 1987;Stanley et al. 1994). Such studies provide long-term movement data but little information aboutshort-term movements. Acoustic tracking systemshave been used for more than 20 years to identifyshort-term movements of fishes (Stasko and Pin-cock 1977), especially for freshwater species. Mat-thews (1990a, 1990b) was one of the first scientiststo use acoustic systems to track shallow-water(,50 m deep) rockfishes. She brought copperrockfish Sebastes caurinus, quillback S. maliger,and brown rockfish S. auriculatus to the surfacefrom a depth of 25 m or less, tagged them exter-nally with sonic transmitters, and successfully fol-lowed them using scuba and surface trackingequipment. Results provided information about thedifferences in seasonal habitat use of several dif-ferent species and age groups.

Despite the successes of tagging shallow-waterspecies, the methods of sonic tag attachment andlong-term tracking are problematic for deepwaterspecies. Traditional tag–recapture studies thatbring fish to the surface place a great deal of stresson fish with closed swim bladders. A large com-

598 STARR ET AL.

FIGURE 1.—Location of the Soquel Canyon study sitein Monterey Bay, California, locations of fish release,and receiver locations.

ponent of this stress is caused by the barotraumaassociated with rapid decompression. Typicalbarotrauma symptoms include everted stomachs,cloudy eyes, eyes bulging from orbits, and dis-torted flesh and scales (Parrish and Moffitt 1993).Handling mortality thus can be exceedingly highwhen deepwater species with swim bladders arebrought to the surface. Also, many rockfishes withinflated swim bladders have difficulty returning tothe bottom, even after the swim bladder is punc-tured (Coombs 1979).

As a result, few people have successfully taggedfish species inhabiting water depths greater than50 m. Priede and Smith (1986) were able to deploysonic tags and track fish for a few hours in a deep-water species by enticing abyssal grenadiers Cor-yphaenoides yaquinae to ingest sonic tags wrappedin bait. Parrish and Moffitt (1993) used scuba gearto tag juvenile Hawaiian snapper Pristipomoidesfilamentosus at depth; they reeled hooked fish towithin 30 m of the surface where divers orallyinserted the sonic tags. Pearcy (1992) also tried,with yellowtail rockfish Sebastes flavidus, to in-crease tag retention time for the oral-insertionmethod by adding barbed hooks to the sonic tags;retention times ranged from 2 to 89 d.

Our goal was to place acoustic tags on green-spotted rockfish Sebastes chlorostictus and bocac-cio S. paucispinis and track them for a 3-monthperiod. To prevent tag regurgitation, minimize fishmortality caused by barotrauma, and eliminate in-fection caused by external attachment, we devel-oped scuba techniques to surgically implant tagsat feasible depths. In addition to problems of tagattachment, sonic tracking studies of fish move-ments to date have been limited by weather andlogistical problems associated with tracking froma surface vessel. Therefore, we also developedtechniques to place recording receivers on the sea-floor for a 3-month period to obtain semicontin-uous information about fish movements.

Methods

Tag experiment.—Before tagging the two rock-fish species with sonic tags in the field, we testedthree different attachment methods at the Monte-rey Bay Aquarium in Monterey, California. Acous-tic tag dummies, with the same dimensions andweight of real acoustic tags, were attached to kelprockfish S. atrovirens, gopher rockfish S. carnatus,olive rockfish S. serranoides, and vermilion rock-fish S. miniatus in three different treatment groups:oral insertion, dorsal attachment to the muscula-ture just below the dorsal fin, and surgical insertion

within the abdominal cavity. A control with no tagattachment was included. Each attachment methodwas replicated five times. For each tag group, weassessed duration of tag retention, abnormal orhindered swimming behavior, weight gain or lossover a 6-week period, and the presence or absenceof external skin irritations.

Study site and fishing methods.—The study siteis approximately 20 km west of the port of MossLanding in Monterey Bay, California (Figure 1).It lies on the flank of the submerged Soquel Can-yon in 100–250 m of water and contains bencheswith soft sediment and rock outcrops surroundedby steep sediment slopes and rock walls (Yoklav-ich et al. 1993, 1995). Commercial and recrea-tional fishing for rockfishes is common in the area.General locations for sampling were obtained fromknown sportfishing locations and from previoussidescan sonar and submersible surveys in SoquelCanyon (Deb Wilson-Vandenberg, California De-partment of Fish and Game and Mary Yoklavich,National Marine Fisheries Service, unpublisheddata). During the first year, rockfishes were caughtusing two baited longlines deployed from a re-search vessel. During the second year, a commer-cial fisherman was hired to catch fish using mod-ified trolling gear. The gear contained a 10–15-m-long monofilament line attached just above thedown weight; jigs were placed about 1 m apart on0.25-m-long leaders. A small float at the end of

599ROCKFISH TAGGING AND TRACKING

FIGURE 2.—Close-up view of the V-board attached to the surgery center, showing equipment used to tag deepwaterrockfish: (A) hypodermic needles to bleed air from swim bladder, (B) external dart tag applicator with tags, (C)sonic tag, (D) scalpel and forceps, (E) surgical stapler, and (F) liquid antibiotic.

the line kept the jigs trailing the down weight ata uniform depth. In both years, differential globalpositioning system (GPS) coordinates of the catchlocation were recorded. In both years, fishing lineswere retrieved at about 20 m/min, a pace slowenough to avoid decompression problems with thefish. Fishing lines were marked 20 m above thefirst hook, as an indicator to stop retrieval of thelines.

Tagging gear.—After the longlines were de-ployed or while the fisherman was trolling, thetagging equipment was prepared for deployment.The surgery center used was an open-frame boxapproximately 2 m high 3 1 m wide 3 1 m deep.It was constructed of schedule-80 polyvinyl chlo-ride and steel angle framing and equipped with awooden V-board with Velcro straps to hold the fishduring surgery (Figure 2). A 0.4-m2 flopper stop-per was placed in the down-line of the surgerycenter to reduce movements caused by ship roll orpitch (Figure 3). Tagging tools attached to the sur-gery center included a scalpel, forceps, sutures,stapler, antiseptic bottle, acoustic transmitters,

Floy tags, and a tagging gun. A cage for recoveryand release, approximately 1 m long 3 0.4 m high3 0.4 m deep (Figure 4), where the fish wereplaced after tagging, was suspended near the sur-gery center. The cage was constructed of 1-cmrebar with nylon mesh netting around the frame.The down-line of the recovery cage also containeda 0.4-m2 flopper stopper to reduce movementscaused by the ship (Figure 3). The cage wasequipped with a tripping bar and two end doorsthat fell open when the tripping bar contacted theseafloor.

The acoustic tags, Vemco V16 (Vemco Ltd.,Nova Scotia) series tags, were 16 mm in diameterand 80 mm long and weighed 12 g in water. In1997, tags had unique frequencies of 50–78 kHz.In 1998, we used coded telemetry transmitters thatenabled us to put multiple tags on the same fre-quency. Ten frequencies were used, again 50–75kHz. Transmitter power was 153 decibels re 1 uPat 1 m, allowing signal detection at a range of1,000 m or greater under the sea conditions inSoquel Canyon. The transmitters had pulse widths

600 STARR ET AL.

FIGURE 3.—Schematic of diving operations used toconduct underwater surgery.

FIGURE 4.—The recovery cage used to return tagged fish to the bottom; the rotating latches open the cage doorswhen the foot of the trip lever hits the bottom.

of approximately 10 ms and intervals of 10 s in1997 and 10 or 16 s in 1998. In both years, taglife exceeded the length of time the moored re-ceivers were in the water.

Tagging operations.—To avoid swim bladderexpansion and thermal shock to the fish, taggingwas done below the thermocline, at a depth ofabout 20 m. While the fishing line was being re-trieved, the surgery center, recovery cage, and alightly weighted signal line were lowered over theside of the vessel (Figure 3). Once the fishing linewas pulled up to the 20-m mark, the divers enteredthe water. Three divers were used: a surgeon whotagged the fish, an assistant, and a safety diver whomonitored the entire operation and watched forpredators. Divers were usually in hand-contactwith one of the down-lines but did not use tradi-tional tethered blue-water diving techniques (Hei-ne 1986) because they had to move to differentapparatuses underwater. The divers descended thefishing line and searched the first few hooks forrockfish of the appropriate species and size fortagging. If none were present, the safety diver gaveone pull on the signal line to indicate to a deckhandto slowly pull up the fishing line. When a suitablefish was sighted, the diver gave a series of rapid-pull signals to tell the crew to stop hauling up theline. At this point, divers checked the fish; if signs

601ROCKFISH TAGGING AND TRACKING

of excessive barotrauma were not present, the as-sistant surgeon, using a squeeze bottle with 10%quinaldine mixed with isopropyl alcohol, squirtedthe anesthetic near the mouth of the fish. Once thequinaldine had taken effect and the fish was rel-atively motionless, the assistant and surgeon re-moved the gangion and hook from the down line,and transferred the fish to the surgery center, whereit was strapped ventral side up into the V-board.The gangion was clipped into a spring clip on theside of the V-board as a safety feature in case thefish wriggled free.

Once the fish was secure, the swim bladder wasbled with a small syringe needle if necessary, totallength was recorded using a measuring tape affixedto the V-board, and surgery was performed. First,the scalpel was used to gently scrape the scalesaway from the abdomen, and a small incision(about 2 cm long) was made through the skin be-tween the anus and pelvic fins, taking care not tocut into the organs below. Betadine antiseptic wassqueezed into the incision to help prevent infec-tion, and the acoustic transmitter was inserted. Tohelp close the incision and keep the staples fromhitting organs below the skin during stapling, theassistant pinched the skin around the incision withforceps while the surgeon closed the incision withthree or four stainless steel staples. The surgeonthen placed a Floy anchor tag into the musculaturebelow the dorsal fin. In 1998, we changed to syn-thetic sutures to close the incision after we realizedthat the staples had pulled out of some of the largerfish. After surgery, the tagged fish was carefullytransferred to the recovery–release cage, and thehook was removed from its mouth. Each fish wasobserved in the recovery cage for a few minutesto ensure it was sufficiently vigorous to release.Divers then swam back to the fishing line, gave asingle pull on the signal line to restart retrievaland obtain more fish. The entire tagging operationtook approximately 6 min/fish underwater, thuseasily allowing for two to three fish to be taggedduring one dive.

When all divers and equipment, except the re-covery cage, were back on board, the sonic tagwas checked for proper function by deploying ahand-held omni-directional hydrophone attachedto a Vemco model VR-60 receiver. Once we wereassured that the tag was functional, and the fre-quency and depth transmissions were correct, therecovery cage was slowly towed back to the lo-cation where the fish was caught. As the cage waslowered to the bottom, depth signals were moni-tored to ensure the release system was working

properly. The cage was assumed to be on the bot-tom when the deployment line appeared slack andthe depth signals remained steady. The cage wasraised 2–3 m and relowered to ensure the trippingmechanism properly functioned, then left on thebottom for a few minutes to allow the fish to swimout. As the cage was retrieved, the transmitterdepth signal was closely monitored to ensure thefish was out of the cage and was not being pulledback to the surface.

Fish tracking.—Vemco VR-20 subsurface re-ceivers were the primary tools used to monitor fishmovements. Using a Delta submersible, we teth-ered receivers to the bottom in both years withsubsurface moorings (Figure 5). In the second yearof the study, two receivers were deployed usingan anchor and a surface buoy for short periodsfrom August 17 through September 10, 1998, be-cause tagging operations commenced 1 month be-fore the submersible was scheduled to deploy theunderwater moorings. These receivers were placednear the locations at which fish were released: thenortheastern portion (site 1) and southwestern por-tion (site 2) of the study area.

In 1997, to conserve battery power for the du-ration of the study, each receiver was programmedto turn on for 6 min and then off for 24 min in acontinuous cycle. In 1998, receivers were pro-grammed to turn on for 10 min each hour. For eachtag signal heard, the receiver recorded the tag num-ber, tag frequency, the date and time of signal re-ception, and the depth of the tag; in 1998, receiversalso recorded signal strength, gain, and noise.

During the submersible deployment of receiv-ers, the pilot and observer first searched for anappropriate site to place the receiver. Care wastaken to choose a site far enough away from thecanyon wall and associated boulders to minimizeacoustic shadows and close reflections that mightaffect signals reaching the receivers. Mooring an-chors also had to be placed on relatively level sub-strates to prevent the receivers from being draggeddown the side of the submarine canyon. When asuitable location was found, the differential GPSposition of the Delta submarine was recorded andthe mooring was released.

The positions of receiver deployment were cho-sen to span the distribution of release locations ofthe tagged fish (Figure 1). In 1997, four receiverswere placed on a ledge along the wall of the sub-marine canyon approximately 500 m apart on Oc-tober 7 and retrieved by a remotely operated ve-hicle (ROV) on January 5, 1998. In 1998, six re-ceivers were placed about 1,000 m apart on Sep-

602 STARR ET AL.

FIGURE 5.—Schematic of receivers moored to theocean bottom at depths above the release depth of thefish. The receivers were inverted to minimize the chanceof a signal reception shadow.

FIGURE 6.—Schematic of the canyon wall at the So-quel Canyon study site in 1998 and relative locations ofhydrophones.

tember 16 and retrieved by ROV on December 30,1998. Two of the receivers were located in about100 m of water on the relatively flat bottom abovethe canyon rim. The other four receivers wereplaced in deeper water on flat shelves or gentlysloping walls below the canyon rim (Figure 6).Approximately 3 months after deployment, theMonterey Bay Aquarium Research Institute’s ROVVentana, and its support ship, the R/V Point Loboswere used to locate and retrieve the receivers.

The receivers we used were omnidirectional;and a recording of a tag transmission indicated thatthe fish was within an approximate horizontal ra-dius of about 1,000 m. To increase the amount of

information available, we placed the tagged fishand receivers along the side of a submarine canyonthat trended northeast to southwest. Tag receptionsof a given depth could not have originated fromother areas due to the topography of the canyonwall. The resulting overlapping receiving zones ofthe receivers, combined with the depth transmis-sion, reduced the number of possible locations ofthe fish and thus further defined the position andmovements of the tagged fish.

The Delta submersible was also used to verifythat tagged fish were alive. We placed a VemcoVR-10 P high-pressure directional hydrophone onthe bow of the submersible and fed signals to aVR-60 receiver operated by a scientist inside thesubmersible. At the start of a dive designed tolocate individual fish, the submersible descendedand rested on the bottom. The submersible pilotoriented the vehicle in a compass direction whilethe scientist scanned all programmed frequenciesand noted signals from transmitters. After all 10frequencies were scanned, the pilot rotated thesubmersible approximately 45 degrees and repo-sitioned the vehicle on the bottom, whereupon thescanning procedure was repeated. The scientistscanned frequencies and noted signals at eachcompass bearing as the submersible was rotatedincrementally in a complete circle.

After the circle was complete, the scientist chosethe strongest signal to follow from a tag that pre-viously had not been seen. The submersible pilot

603ROCKFISH TAGGING AND TRACKING

FIGURE 7.—Percentage of the time that receivers re-corded transmissions from transmitters placed at knowndistances away.

then slowly drove in the direction of that signal.As long as the signal remained strong, the pilotremained on a heading. If the signal started tobecome weak, the pilot repositioned the submers-ible on the bottom and rotated it left and right untilthe signal was again strong. By the end of the fieldseason, pilots were able to make small course cor-rections as the submersible was moving by listen-ing to the strength of the signal emitted from theVR-60 receiver. This technique enabled us to lo-cate and observe tagged fish and verify they werealive and swimming in schools with other fish.

Signal reception range.—In 1998, we placedfour tags on the bottom for the duration of thestudy to use as references for comparison of sig-nals from a stationary object and from a movingfish and to compare changes in range of signalreception with changes in temperature and salinityof the water. Tags on the bottom may not be re-corded by the VR-20 receivers as far distant astags in live fish because transmissions from a tagin the mud may arrive at the moored receivers asmultipath signals and be rejected as nonvalid sig-nals by the receiver software. However, they doprovide an estimate of the frequency of electronicerror associated with depth transmissions, indi-cating the effective range of the tags implanted infish and the variability of signal strength recordedby the moored receivers.

To test signal reception range, we compared thenumber of times a receiver was in its 10-min re-cording mode (‘‘bin’’) with the number of times areceiver recorded at least one tag signal in a binfor tags at known distances from receivers. Eachreceiver except number 2 was in recording mode2,535 times from September 16 through December30, 1998. Receiver number 2 was accidentallyhauled up by a commercial fishing vessel October26, 1998; thus, it contained only 961 recordingbins. The results indicate that receivers recorded80% or more of the transmitted signals when thetag was closer than 800 m (Figure 7), except whenthe tag was not in a straight line to the receiver.In cases such as with tag 6, which was locatedclose to receiver number 6 but below on a steepslope at 185 m, the effective receiving distancewas much smaller.

To test depth estimates, we placed the referencetags on the bottom at known depths to estimatethe precision of the depth transmissions. Pressuresensors in the tags allowed us to record depths oftagged fish (Figure 8) with an accuracy of 2% ofthe depth (Vemco, unpublished data). At a depthof 100 m, the accuracy of the depth was within 2

m, a value equivalent to the tidal range in Mon-terey Bay. More than 99.5% of the signals recordedfrom tag transmissions were within 2 m of theactual depth of the tag (Table 1), indicating thatwe could resolve vertical movements of the fishto within approximately 2 m, without correctingfor tidal variation.

Results

Tag Experiment on Captive Fish

Surgical insertion was selected as the best meth-od for sonic tag attachment in rockfishes, basedon experimental results of tag retention time,weight change, apparent behavior, and the extentthat attachment incisions had healed (Table 2). Weobserved no mortalities or abnormal swimming inany of the treatment fishes. One dorsal Floy tagfell off after 2 weeks, and for all of the dorsallytagged fishes, the site of tag attachment was stillraw and unhealed after 6 weeks. Fish with dorsaltags gained significantly less weight than the con-trol fish (Wilcoxon’s signed-rank test, P 5 0.04).Three of the five fish with dorsal tags lost weightduring the study. All but one of the orally insertedtags were regurgitated within the first 2 weeks, andthose fish gained weight or remained stable afterthey had regurgitated the tags. All of the fisheswith surgically implanted tags healed completelyand had either gained weight or remained at a rel-atively steady weight after 44 d. There was nodifference in weight gain between control and sur-gically tagged fish (Wilcoxon’s signed-rank test,P 5 0.69).

Tagging and Tracking

During the first year we successfully tagged andreleased 6 greenspotted rockfish 35 to 39 cm long,

604 STARR ET AL.

FIGURE 8.—Depth transmissions for a 1-week period in 1998 recorded from tag 7 in a bocaccio, showing thetypical range of vertical movements.

TABLE 1.—Frequency of signal receptions showingdepths within 62 m of actual depths of tags located onthe bottom.

Tagnum-ber Depth (m)

Total numberof signals

Signals within62 m of actual depth

Number Percent

268

11

100185

9097

15,514854

9,31619,078

15,495851

9,31319,074

99.8899.6599.9799.98

and in the second season we tagged 16 bocaccio35 to 58 cm long (Table 3). The time from place-ment of each fish into the recovery cage to thetime the cage doors were tripped at the bottomranged from 15 to 80 min. Two obvious mortalitiesoccurred during the tagging process in 1997. Inone case, the fish did not recover from the surgeryto the point that we felt confident about its sur-vival. In the other case, the fish was successfullytagged, but then accidentally brought to the surfacewhen the recovery cage failed to open at the bot-tom.

In 1998, we relocated three tagged bocaccio us-ing the directional hydrophone mounted on a sub-mersible. The fish were located in high-relief hab-itats with other untagged bocaccio. The schooledfish were actively moving both vertically and hor-izontally along the high-relief bottoms. In additionto the tagged fish, we were able to locate six trans-mitters on the seafloor, all were on flat, soft bot-toms and sitting upright in fine, undisturbed sed-iment. Possibly, the fish died before the tag fell

out or a predator moved the tag; however, we be-lieve the staples pulled out of live fish, causingthe tags to fall to the seafloor, because we saw noevidence of scavengers around the tag and becausewe noticed that some surgical staplers did not workas well as others. We recovered two of the tags toimplant in other fish, and used the remainder asreference tags.

In the first year of the study (1997), a problemwith internal cable connections caused a malfunc-tion with one of the four receivers deployed. Thethree remaining receivers recorded data through-out the study in 1997 (Table 4). Signals from alltags, except tag 1, were recorded throughout the1997 study period; the total number of transmis-sions recorded from each tagged fish ranged from156 to 24,132. Signals from tag 1 were heard for18 h, then not again until 67 d later. In 1998, thereceivers placed on surface buoys in August andearly September recorded continuously; total num-ber of tag transmissions recorded for each of thetagged fish in that time ranged from 0 to 9,531(Table 5). Signals from the 4 of the 16 tagged fishwere only recorded on the day they were releasedor between August 17 and September 10. The sixreceivers that were deployed on subsurface moor-ings all functioned properly. The moored receiversrecorded signals from 12 of the 16 tagged fish,with the total number of signals recorded for eachtag ranging from 0 to 19,213 (Table 6).

Elapsed time between a tag’s first and last re-corded signal ranged from 1 to 140 d (Table 3).Receiver 1 recorded the fewest signals; it was lo-

605ROCKFISH TAGGING AND TRACKING

TABLE 2.—Results of tag experiments conducted inaquaria.

Rockfishspecies

Weight (kg)

Start End

Weight change

Kilograms Percent

Reten-tiontime(d)

Control

GopherKelp

OliveVermillion

Mean

0.520.410.700.551.43

0.580.550.840.561.35

0.060.150.140.01

20.080.06

11.936.419.71.8

25.6012.8

Oral treatment

GopherKelp

OliveVermillion

Mean

0.520.600.590.821.43

0.590.650.670.881.35

0.070.050.080.06

20.080.04

13.58.3

13.97.5

25.67.5

31

12224

Dorsal treatment

GopherKelp

OliveVermillion

Mean

0.580.570.590.860.85

0.590.590.580.810.59

0.020.02

20.0120.0520.2620.06

2.84.2

21.025.8

230.926.2

442944261331

Surgical treatment

GopherKelp

OliveVermillion

Mean

0.600.660.621.101.97

0.580.810.781.131.96

20.020.150.160.03

20.010.06

23.323.125.72.7

20.39.6

444444444444

TABLE 3.—Summary of tagging operations in 1997 and1998.

Tagdate

Tagnum-ber

Fre-quency(kHz)

Totallength(cm)

Releasedepth(m)

Datelast

signal(1998)

Deltatimea

(d)

Greenspotted rockfish

1997Sep 17Sep 24Sep 24Oct 16Oct 17Oct 21

2367

101

57.060.067.372.078.054.0

373839353535

220232204160160144

Jan 5Jan 5Jan 5Jan 5Jan 5b

111104104828167

Bocaccio

1998Aug 12Aug 13Aug 13Aug 14Aug 25Aug 25Aug 31Aug 31Sep 1Sep 2Sep 2Sep 29Sep 29Sep 29Sep 30Sep 30

49

1073

1718202621241213142527

57.069.075.063.050.054.054.060.078.065.572.050.057.069.078.072.0

35505257474547514945515247585548

96959895

10614099999892929595959696

Sep 5Dec 30Sep 9Dec 30Sep 8Dec 30Dec 30Oct 5Sep 1Sep 20Sep 2Oct 11Oct 1Dec 30Nov 10Dec 30

2514028

13915

128122361

181

133

934292

a Number of days between release of a tagged fish and the lastsignal reception from that tag.

b December 26, 1997.

TABLE 4.—Summary of the number of times each tagwas recorded by each receiver (rcvr) when it was in re-ceiving mode in 1997.

Tagnumber Rcvr 1 Rcvr 2 Rcvr 3 Total

12367

10

442,726

9441,9682,2521,960

7310,7664,404

10,7542,6583,667

3910,6404,240

11,1931,5511,135

15624,1329,588

23,9156,4616,762

cated at the northeastern-most portion of the studyarea (Figure 1). Receiver 4 contained the mostrecorded signals, but it was closest to the releaselocations of the majority of the tagged fish. Trans-missions from tags 7, 18, and 25 were recordedby all receivers, indicating movements of fishacross the study area.

Discussion

The results from our study indicate that surgicalinsertion is the most appropriate method for sonictag attachment in rockfishes. Fish with surgicallyimplanted sonic tags gained weight in experimen-tal aquaria, indicating that feeding behavior wasonly minimally affected by the tags. Their inci-sions were closed after 7–10 d and were fullyhealed after 30 d. Our observations that some rock-fishes rapidly regurgitated orally implanted tagsand the weight gain of our experimental fish sug-gest that surgical procedures result in the leastamount of behavioral change. This conclusion issupported by Lucas and Johnstone’s (1990) ob-servations of tag regurgitation and Mortensen’s

(1990) observation that stomach transmitters in-hibited feeding more than ones imbedded in thevisceral cavity. Similarly, Mellas and Haynes(1985) and Moser et al. (1990) reported that im-plantation of tags resulted in minimal behavioralchange. The undetectable difference in fish be-havior after surgical implantation of tags contrastsmarkedly to Pearcy’s (1992) observation that anexternally attached tag caused one yellowtail rock-fish to list to one side.

The combination of fishing and diving from one

606 STARR ET AL.

TABLE 5.—Summary of number of times tag transmis-sions were recorded by receivers temporarily placed in thestudy area early in the study period in 1998 (see text fordescription of location of site 1 and site 2).

Tagnumber Site 1 Site 2 Total

3479

10171820212426

135186

9,52393

1432,537

a

a

a

a

5598

1,55610

180

47310

140245

9,5311,565

4143

2,5550

47310

a Receivers were not programmed to record signals from tags 20,21, 24, or 26 at site 1.

TABLE 6.—Summary of number of times each tag was recorded by each moored receiver (rcvr) when it was inreceiving mode in 1998.

Tagnumber Rcvr 1 Rcvr 2 Rcvr 3 Rcvr 4 Rcvr 5 Rcvr 6 Total

3479

101213141718202124252627

00

475000000

905000

1200

00

1,651009070

1,449700

2600

00

3,44470

2654

1390

3,1654

320

780

77

00

2,343151

03882

9,0252,6213,250

000

260

10

00

1043,421

026

14836

03282083

2204

09,341

00

973,788

09

6720

51800

890

9,785

00

8,1147,367

0108351

9,2092,6219,148

39115

2435

019,213

Total 1,392 3,149 7,026 17,546 13,713 13,896 56,722

vessel proved to be logistically difficult. Low catchrates using hook-and-line gear and variable timebetween fish capture for each angler made it dif-ficult to conduct efficient diver operations. Thus,we used longline gear in 1997 to improve effi-ciency by enabling divers to remain at depth andremove fish from hooks as the longline was re-trieved. We also simplified fishing operations in1998 by working with a commercial fisherman us-ing modified trolling gear that was very effectiveat selectively catching bocaccio. It was similar totrolling gear used for Pacific salmon Onchorynchusspp. in the region (Starr et al. 1998) but containeda heavier down-weight and had different jigs.Working with a second vessel in 1998 enabled usto focus efforts on dive operations, rather than di-

viding our attention between catching and taggingfish. The troll gear also was more efficient to workwith underwater than the longline gear used in1997 because all the hooks were concentrated ina small distance and divers did not deplete air re-serves as they did when waiting for the longlineto be retrieved.

On several occasions, we saw California sea li-ons Zalophus californianus at the surface feedingon rockfish that probably came off the fishinglines. A few sea lions also attempted to take fishfrom the fishing lines during dive activities. Bluesharks Prionace glauca may have also eaten a fewfish because the fishing gear occasionally returnedto the surface missing hooks. According to localfishers, blue sharks commonly remove hookedrockfishes from their lines during August and Sep-tember in Monterey Bay.

When fish were caught and slowly reeled to adepth of 20 m, the methods developed for divingin open water were very reliable for performingthe underwater surgery. Although surgical oper-ations were successfully completed by two divers,we believe a three-person dive team is required tosafely and efficiently conduct the tagging opera-tions. The safety diver was essential to monitordive activities of the surgeon and assistant, actionsof potential predators, and overall conditions ofthe dive, thus enabling the primary divers to con-centrate on handling the fish. The safety diver en-sured the surgeon and assistant were not entangledin the fishing line or lines from the surgery centerand ensured that all divers monitored their air con-sumption. The safety diver also carried a long stick

607ROCKFISH TAGGING AND TRACKING

to keep aggressive sea lions at a safe distance.Although the stick was available to ward off bluesharks, they were rarely seen, seemed only curious,and posed no danger for the divers.

Effects of barotrauma on captured fish seemedto be minimal when we retrieved the longline ata relatively slow rate. We chose a retrieval rateslightly faster than the recommended rate of ascentfor scuba divers (Heine 1999). Almost no bocaccioshowed evidence of barotrauma, and swim blad-ders were intact, whereas we had to deflate theswim bladder of most of the greenspotted rockfishwe tagged.

This prescreening of fish for surgery and pos-toperation evaluation enabled us to minimize mor-talities caused by the surgery. Patterns of signalreception by different receivers demonstratedmovements of fish back and forth between receiv-ing zones in 1997 and indicated that the six taggedfish survived the tagging process. Tag transmis-sions from five fish were recorded over the entiretime the receivers were in the water. Signals fromthe remaining greenspotted rockfish (tag 1) wereheard for a short time and then not until the endof the study, suggesting movement of the taggedanimal.

Based on our experience in the first year of thestudy, we assume that the mortality rate was lowin 1998 as well. We are unable to estimate or verifythe mortality rate, however, because many of thetagged fish appeared to leave the study area. Sig-nals from three of the tagged bocaccio ceased with-in 1–3 d, three within 3 weeks and two within amonth (Table 3). These fish either left the studyarea, died and were swept deeper into the sub-marine canyon, or had tags that failed. Signalsfrom three other tagged bocaccio were recordedfor at least 6 weeks, after which signals ceased.Signals from those three fish (tag numbers 17, 20,and 25) were recorded again later in the study afteran absence of 27, 126, and 14 d, respectively. Theintermittent pattern of these signals indicates thefish were actively moving because signals fromreference transmitters placed on the bottom wererecorded during the entire study. Five of the taggedfish remained in the study area for more than 3months and showed signs of movement based onthe pattern of signal receptions by the moored re-ceivers.

Occurrences of receiver cross-talk in 1997 and1998 also indicated movements of live fish. Cross-talk occurs when a tagged fish gets close to a re-ceiver (e.g., within 0–50 m) and a tag transmissionis recorded on two different frequencies due to

signal saturation of the receiver. In 1997, receivers2 and 3 each recorded cross-talk of signals fromthe same two fish (tags 2, 6) at several differenttimes, indicating those fish alternately swam closeto one receiver and at a later time swam close toa second receiver more than 300 m away. In 1998,receiver 5 recorded cross-talk from tag number 23as it moved into and out of the proximity of thereceiver.

The technique of placing receivers along ledgeson the side of a submarine canyon enabled us torefine the position of the tagged fish, but it alsocaused many acoustic shadows and echoes. Thehard, steep walls that undulate along the side ofthe canyon may have occasionally caused echoesand an original signal transmission to coincide,preventing the receivers from recording a validsignal. Thus, some of the time bins in which thereceivers were in recording mode contained no sig-nals from nearby tagged fish. Some of the lapseswere probably also due to the tendency of somerockfishes to take shelter under rocks as well. Fromthe surface, we occasionally heard weak signalsthat were unusually high-pitched and sounded‘‘tinny.’’ In other studies of shallow-water rock-fishes, we have experienced the same type of re-ception for several hours at a time when fish takeshelter under a rock or ledge. The signal returnsto full strength and timbre when the tagged fishleaves the crevice.

As fishing pressure on rockfish populations in-creases, managers are considering new conserva-tion methods, including the use of area manage-ment and marine reserves. Marine reserves areconsidered to be effective ways to conserve pop-ulations of harvested species, especially sedentaryrockfishes (Yoklavich 1998), and may possibly en-hance nearby fisheries (Sladek Nowlis and Yok-lavich 1998; Johnson et al. 1999). To maximizeeffectiveness, however, reserves should be de-signed to accommodate the life history patterns ofrockfish species (Carr et al. 1998; Starr 1998). Inthis respect, understanding the home range anddaily movements of rockfishes is critical to un-derstanding of the value of marine reserves. Todate, studies of home range and movements ofdeepwater rockfishes have been limited by prob-lems associated with barotrauma caused by bring-ing fish to the surface to tag. The in situ taggingprocedures we developed alleviated many prob-lems associated with surface tagging. We were ableto develop techniques that provided informationabout horizontal and vertical movements of tworockfish species during all hours and all days for

608 STARR ET AL.

a 3-month period. These techniques appear to bea promising means for studying movements ofdeepwater species with swim bladders and mayprovide the means for obtaining increasingly im-portant information more about fine-scale move-ments of fishes.

Acknowledgments

A project of this complexity requires the helpof many people. We would like to especially thankFred Voegeli of Vemco, Inc., for his help with theelectronic equipment, John O’Sullivan and theMonterey Bay Aquarium personnel for helping de-sign the underwater surgery center and allowingus to conduct tagging experiments, and Jason Fel-ton for helping us tag rockfish in 1998. We thankDave Lindquist for his help in the tag retentionexperiment, Tom Williams for helping with sur-gical procedures, and the people who helped uscatch the fish, especially Dempsey Bosworth fromthe F/V Beticia, and Lee Bradford, Joe Bizzaro,and Kate Stanbury. Aldo Derose designed andbuilt the recovery cage. Jean DeMarignac helpedconfigure the current meter. We thank the peoplewho provided the ships and submersibles and theircrew, including the ship operations staff of MossLanding Marine Laboratories, Wayne Kelly of Al-ladin Charters, the crew of the C/V Cavalier, thepilots of the submersible Delta, Dave Slater andChris Ijames, and the crew of the R/V Point Lobosand ROV Ventana pilots. Greg Cailliet graciouslyprovided funding for added ship time and helpedevaluate the data. We also thank Kirsten Carlsonfor scientific illustrations and Lynn McMasters forgraphics help. Funding for this project was pro-vided by the West Coast and Polar National Un-dersea Research Center, University of CaliforniaSea Grant Extension Program, and Moss LandingMarine Laboratories.

References

Carr, M. H., and ten coauthors. 1998. Working groupon design considerations. Pages 143–148 in M. M.Yoklavich, editor. Marine harvest refugia for westcoast rockfish: a workshop. NOAA Technical Mem-orandum NMFS-SWFSC-255.

Coombs, C. I. 1979. Reef fishes near Depoe Bay,Oregon: movement and the recreational fishery.Master’s thesis. Oregon State University, Corvallis.

Culver, B. N. 1987. Results from tagging black rockfish(Sebastes melanops) off the Washington and north-ern Oregon coast. Pages 231–240 in Proceedings ofthe international rockfish symposium. University ofAlaska, Sea Grant Report 87-2, Fairbanks.

Heine, J. N., editor. 1986. Blue water diving guidelines.

California Sea Grant College Program, PublicationT-CSGCP-014, La Jolla.

Heine, J. N. 1999. Scientific diving techniques: a prac-tical guide for the research diver. Best PublishingCompany, Flagstaff, Arizona.

Johnson, D. R., N. A. Funicelli, and J. A. Bohnsack.1999. Effectiveness of an existing estuarine no-takefish sanctuary within the Kennedy Space Center,Florida. North American Journal of Fisheries Man-agement 19:436–453.

Karpov, K. A., D. P. Albin, and W. H. VanBuskirk. 1995.The marine recreational finfishery in northern andcentral California: historical comparison (1958–1986), status of stocks (1980–1986), and effects ofchanges in the California Current. California De-partment of Fish and Game Fish Bulletin 176.

Lucas, M. C., and A. D. F. Johnstone. 1990. Observa-tions on the retention of intragastric transmitters,and their effects on food consumption in cod, Gadusmorhua L. Journal of Fish Biology 37:647–649.

Mathews, S. B., and M. W. Barker. 1983. Movementsof rockfish (Sebastes) tagged in northern PugetSound, Washington. Fishery Bulletin 82:916–922.

Matthews, K. R. 1990a. An experimental study of thehabitat preferences and movement patterns of cop-per, quillback, and brown rockfishes (Sebastes spp.).Environmental Biology of Fishes 29:161–178.

Matthews, K. R. 1990b. A telemetric study of the homeranges and homing routes of copper and quillbackrockfishes on shallow rocky reefs. Canadian Journalof Zoology 68:2243–2250.

Mellas, E. J., and J. M. Haynes. 1985. Swimming per-formance and behavior of rainbow trout (Salmogairdneri) and white perch (Morone americana): ef-fects of attaching telemetry transmitters. CanadianJournal of Fisheries and Aquatic Sciences 42:488–493.

Mortensen, D. G. 1990. Use of staple sutures to closesurgical incisions for transmitter implants. Pages390–393 in N. C. Parker, A. E. Giorgi, R. C. Hei-dinger, D. B. Jester, Jr., E. D. Prince, and G. A.Winans, editors. Fish marking techniques. Ameri-can Fisheries Society, Symposium 7, Bethesda,Maryland.

Moser, M. L., A. F. Olson, and T. P. Quinn. 1990. Effectsof dummy ultrasonic transmitters on juvenile cohosalmon. Pages 353–356 in N. C. Parker, A. E. Gior-gi, R. C. Heidinger, D. B. Jester, Jr., E. D. Prince,and G. A. Winans, editors. Fish marking techniques.American Fisheries Society, Symposium 7, Bethes-da, Maryland.

Pacific Fishery Management Council. 1995. Status ofthe Pacific coast groundfish fishery through 1995and recommended biological catches for 1996:stock assessment and fishery evaluation. PacificFishery Management Council, Portland, Oregon.

Parrish, F. A., and R. B. Moffitt. 1993. Subsurface fishhandling to limit decompression effects on deep-water species. Marine Fisheries Review 54(3):29–32.

Pearcy, W. G. 1992. Movements of acoustically-tagged

609ROCKFISH TAGGING AND TRACKING

yellowtail rockfish Sebastes flavidus on HecetaBank, Oregon. Fishery Bulletin 90:726–735.

Pearson, D. E., and S. Ralston. 1990. Trends in landings,species composition, length-frequency distribu-tions, and sex ratios of 11 rockfish species (GenusSebastes) from central and northern California ports(1978–88). NOAA Technical Memorandum NMFS-SWFC-145.

Priede, I. G., and K. L. Smith. 1986. Behaviour of theabyssal grenadier, Coryphaenoides yaquinae, mon-itored using ingestible acoustic transmitters in thePacific Ocean. Journal of Fish Biology 29 (Supple-ment A):199–206.

Ralston, S. 1998. The status of federally managed rock-fish on the U.S. west coast. Pages 6–16 in M. M.Yoklavich, editor. Marine harvest refugia for westcoast rockfish: a workshop. NOAA Technical Mem-orandum NMFS-SWFSC-255.

Sladek Nowlis, J., and M. Yoklavich. 1998. Reservedesign from models of fish transport. Pages 32–40in M. M. Yoklavich, editor. Marine harvest refugiafor west coast rockfish: a workshop. NOAA Tech-nical Memorandum NMFS-SWFSC-255.

Stanley, R. D., B. M. Leaman, L. Haldorson, and V. M.O’Connell. 1994. Movements of tagged adult yel-lowtail rockfish, Sebastes flavidus, off the west coastof North America. Fishery Bulletin 92:655–663.

Starr, R. M. 1998. Design principles for rockfish re-

serves on the U.S. west coast. Pages 50–63 in M.M. Yoklavich, editor. Marine harvest refugia forwest coast rockfish: a workshop. NOAA TechnicalMemorandum NMFS-SWFSC-255.

Starr, R. M., K. A. Johnson, N. Laman, and G. M. Cail-liet. 1998. Fishery resources of the Monterey BayNational Marine Sanctuary. California Sea Grant,College System Publication T-042, La Jolla.

Stasko, A. B., and D. G. Pincock. 1977. Review ofunderwater biotelemetry, with emphasis on ultra-sonic techniques. Journal of the Fishery ResearchBoard of Canada 34:1261–1285.

Yoklavich, M. M., editor. 1998. Marine harvest refugiafor west coast rockfish: a workshop. NOAA Tech-nical Memorandum NMFS-SWFSC-255.

Yoklavich, M. M., G. M. Cailliet, H. G. Greene, and D.Sullivan. 1995. Interpretation of sidescan sonar re-cords for rockfish habitat analysis: examples fromMonterey Bay. Alaska Department of Fish andGame Special Publication 9:11–15. (Fairbanks.)

Yoklavich, M. M., G. M. Cailliet, and G. Moreno. 1993.Rocks and fishes: submersible observations in asubmarine canyon. Pages 173–181 in J. N. Heine,and N. L. Crane, editors. Diving for science. 1993:proceedings of American academy of underwaterscientists, 13th annual scientific diving symposium.American Academy of Underwater Scientists, Pa-cific Grove, California.