519 Abstract?Ultrasonic transmitters were surgically implanted into adult tautog (n=27, 400?514 mm TL) to document sea? sonal occurrence and site utilization at four sites situated within known tautog habitat near Cape Charles, Virginia, in lower Chesapeake Bay. Tagged tautog were released at the same sites where originally caught within 2 h of capture. Sites were continuously monitored with automated acoustic receivers between 9 November 1998 and 13 October 1999. Two sites consisted of natural bedform materials and two sites consisted of manmade materials. Ninety-four per- cent of tautog (n=15) released in fall 1998 remained inshore during winter at sustained water temperatures of 5?8?C,rather than moved offshore during winter as documented for tautog off New York, Rhode Island, and Mas? sachusetts. Ninety-one percent (n=10) of tautog released in spring 1999 re? mained inshore during summer when water temperature was 27?C and in the absence of an important food item, blue mussels (Mytilus edulis). These ?nd? ings con?ict with assertions that tautog move to cooler water in summer when water temperatures reach 20?C. Tautog released at natural bedform sites were detected only at these sites throughout the study. Tautog released at manmade structures also displayed high site-utili? zation patterns, but several tautog peri? odically moved 2?10.2 km away from these sites over featureless bottom, a known deterrent to emigration for large temperate labrids in other waters. Ben? thic communities were similar at man- made sites and natural bedform sites, and movement away from manmade sites may have been in?uenced by hab? itat size as well as habitat structure. Understanding temporal and spatial utilization of habitats is an important ?rst step to identifying essential ?sh habitat and to evaluating and protect? ing ?shery resources within Chesa? peake Bay and elsewhere. Manuscript accepted 11 April 2001. Fish. Bull. 99:519?527 (2001). Seasonal occurrence and site-utilization patterns of adult tautog, Tautoga onitis (Labridae), at manmade and natural structures in lower Chesapeake Bay* Michael D. Arendt School of Marine Science College of William and Mary Virginia Institute of Marine Science Gloucester Point, Virginia 23062 Present address: Marine Resources Division, Department of Natural Resources Marine Resources Research Institute 217 Fort Johnson Road Charleston, South Carolina 29422-2559 E-mail address: arendtm@mrd.dnr.state.sc. Jon A. Lucy Sea Grant Marine Advisory Program Virginia Institute of Marine Science Gloucester Point, Virginia 23062 Thomas A. Munroe National Marine Fisheries Service National Systematics Laboratory National Museum of Natural History Washington, D.C. 20560-0153 The labrid Tautoga onitis (tautog) is 1977). Tautog leave inshore waters at a highly prized game ?sh targeted by varying rates between July and Oc? anglers ?shing at natural and man- tober (Cooper, 1966) and are recap- made structure (Briggs, 1977; Lucy tured in coastal waters in fall (Cooper, and Barr, 1994). Tautog are distrib- 1966; Briggs, 1977), consistent with in? uted between Georgia (Parker, 1990) direct observations on seasonal abun? and Nova Scotia (Bigelow and Schro- dance (Stolgitis, 1970; Olla et al., 1974). eder, 1953); peak abundance is found In contrast, tag-recapture studies re- between Massachusetts and the Dela- port limited evidence of a seasonal in- ware Capes.1 Slow growth rate, late age shore-offshore migration for tautog in at maturity, predictable distribution, the Chesapeake Bay and coastal Virgin- and localized population structure sug- ia waters.2 Seasonal abundance data gest high vulnerability to overexploi- also suggest that tautog remain inshore tation (Hostetter and Munroe, 1993). in Chesapeake Bay (Hostetter and Mun- Extended residence at accessible ?sh- roe, 1993) and in Delaware Bay (Eklund ing sites may increase the potential and Targett, 1991) during winter. for overexploitation; thus, residence and site-utilization patterns of tautog throughout this species? distribution * Contribution 2391 of the Virginia Institute of Marine Science, Gloucester Point, Vir? range must be well understood for effec- ginia 23062. tive management of this resource. 1 Atlantic States Marine Fisheries Commis- Tag-recapture studies in New York, sion (ASMFC). 1996. Fishery manage- Rhode Island, and Massachusetts sug- ment plan for tautog, rep. 25, 56 p. [Avail? gest that adult tautog spend spring and able from ASMFC, 1444 Eye Street NW, fall months inshore, may move offshore Washington, DC 20005.] during the warmest summer months 2 Virginia Game Fish Tagging Program. 1995?1999. Marine Resources Commis? (Cooper, 1966; Briggs, 1969), and over- sion, 968 Oriole Dr. South, Suite 102, Vir? winter offshore (Cooper, 1966; Briggs, ginia Beach, VA 23451. 520 Fishery Bulletin 99(4) The tag-recapture method is not a suitable method for evaluating site-utilization patterns because this technique does not provide information on the loca? tion of tagged animals between times of release and recapture. Furthermore, the tag-recapture method requires that tagged animals be recaptured, and be reported as recaptured, before any information is available. Ultrasonic telemetry, however, enables continuous observations on all tagged animals, in their natural environment, without requiring that tagged animals be recaptured (Winter, 1996). Pre? viously, only in one other study (Olla et al., 1974) was ultrasonic telemetry used to monitor adult tau- tog. Olla et al. (1974) tagged and ?tracked? 10 adult tautog ultrasonically in Great South Bay, NY, for up to 80 h after their release. Although an important study, their sample size was small and total observa? tions too limited (<400 h, single season) to document seasonal occurrence and site-utilization patterns for this species. Ultrasonic telemetry was selected to address sea? sonal occurrence and site-utilization patterns of adult tautog in lower Chesapeake Bay, given that tag-recapture methods can be applied only within limitations and given that the poor visibility and strong currents preclude direct underwater observa? tions of this species in this turbid estuary. Rather than collect detailed positional data over short pe? riods of time (days) for a few tautog, we chose to collect seasonal occurrence and site-utilization data Figure 1 for two large groups of tautog (n=16 and 11) at four Location of study sites for telemetric study of tautog released in lower speci?c sites located within known tautog habitat. Chesapeake Bay near Cape Charles, VA. Texeco Wreck (TX) is located in Sites were monitored by using a ?xed, submerged 18 m of water on a plain west of Susquehanna Channel (30?40 m deep). hydrophone array between November 1998 and Sep- Coral Lump (CL), Ridged Bottom (RB), and Airplane Wreck (AW) are tember 1999. The ?rst objective of our study was located in 8?15 m of water on a ?at east of the Susquehanna Channel. N S 10 km 37?05'00"N 07 6? 18 '00 "W 15 m 8 m 10 m 18 m Susquehanna Channel to determine if tautog remained inshore at natural and manmade structures in lower Chesapeake Bay dur? ing winter and summer. The second objective was to docu? ment and describe site-utilization patterns within inshore study sites. Data for daily activity patterns are presented elsewhere (Arendt et al., in press). Materials and methods Tautog were caught, tagged, and released at four sites sit? uated within a 1.5 km ? 6 km area near Cape Charles, Virginia (Fig. 1). Side-scan sonar (Sea Scan Technology, Ltd., White Marsh, VA) was used to measure dimensions of the four study sites and to map the surrounding sea- ?oor. The Texeco Wreck, a 30 m ? 100 m shipwreck, was located in 18 m of water west of the Susquehanna Channel (30?40 m deep) in an area characterized by ?at, relatively featureless bottom topography (Wright et al., 1987). The three remaining sites (Airplane Wreck, Coral Lump, and Ridged Bottom) were located in 8?15 m of water east of the Susquehanna Channel in an area characterized by sand ?ats and deep, mud-bottomed channels (Wright et al., 1987). The Airplane Wreck (40 m ? 20 m) consisted of concrete rubble. The Ridged Bottom (30 m ? 100 m) and Coral Lump (100 m ? 300 m) sites consisted of natural bedforms. Otter trawl, oyster dredge, and underwater video surveys indicated that all sites were densely populated by several species of sponges, colonial bryozoans, mollusks, and crustaceans. Tautog were caught with standard two-hook bottom rigs baited with pieces of blue crab or clam and were brought aboard with a nylon landing net. Tautog were observed in an aerated live well up to 2 h before transmitters were implanted. Total length (mm) and sex (White, 1996) were recorded. Only tautog >400 mm TL were tagged ultrasoni? cally. This minimum size increased the odds of transmit? ters weighing less than 1.25% of ?sh body weight in wa? ter (Winter, 1996), based on size-weight relationships for tautog in Virginia (Hostetter and Munroe, 1993; White, 1996). Tautog >400 mm were also reproductively mature (Hostetter and Munroe, 1993; White, 1996). Surgical procedures were similar to those used in Nemetz and Macmillan (1988), Mortensen (1990), Holland et al. (1993), Szedlmayer (1997), and Thoreau and Baras (1997). In preparation for surgical implantation of trans? mitters, level-four anesthesia (Mattson and Ripple, 1989; Prince et al., 1995) was induced by immersing tautog in a 325-mg/L solution of MS-222. Once anesthetized, a small Arendt et al.: Seasonal occurrence of site-utilization patterns of Tautoga onitis 521 (25-mm) incision was made on each ?sh immediately dor? sal to the ventral midline between pelvic ?ns and anus with a sterilized, disposable razor blade. The transmit? ters was coated in sterile mineral oil and placed into the visceral cavities of tautog with the transducer end of the transmitter facing forward. Braided, polyglycolic acid sutures (Dexon?, I-III), surgical staples (Proximate Plus MD 35W?), and acrylic adhesive (Krazy glue?) were used to close the incision. Betadine was used periodically throughout the surgical procedure and antibiotics (Nu- Flor?) were injected intramuscularly to increase postsur? gical survival (Schramm and Black, 1984; Bart and Dun- ham, 1990; Poppe et al., 1996). Tautog were revived in the aerated live well and released within 0.5 h after surgery. Preliminary evaluation of surgical procedures with ?dum? my? transmitters indicated 100% transmitter retention, 86% survival, and normal swimming, feeding, reproduc? tive behavior, and physiology for tautog >400 mm TL held up to 418 days in captivity (Arendt, 1999). Tautog were fully recovered from surgery <1 to 6 days after release (Arendt, 1999) according to detection patterns recorded by automated acoustic receivers (Arendt and Lucy, 2000). V-16-1H-R256 coded transmitters (16 mm ? 48 mm, 9 g in water; Vemco, Ltd., Shad Bay, Nova Scotia, Canada) were used in our study. Signal repeat intervals for coded trans? mitters (69 kHz) varied randomly between 45 and 75 s, which extended battery life to 111 d. Transmitters were primarily detected with a submerged array of automated acoustic receivers (VR1, Vemco, Ltd.); however, transmit? ters were also detected from a research vessel with acous? tic hydrophones (V10, VH65, Vemco, Ltd.) and an electron? ic receiver (VR60, Vemco, Ltd.). Omnidirectional VR1 receivers were deployed 100?150 m to the west and east of the perimeter of each of the four sites. Detection radius for each receiver was approximately 400 m. Detection areas for both receivers were overlapped to create three distinct reception zones: a central reception zone common to both receivers and two peripheral recep? tion zones unique to either receiver. VR1 receivers were moored 1.5?3.0 m above the sea?oor to provide an unob? structed line-of-sight for transmitter signal reception (i.e. positioned above the ?structure? associated with each site) and to reduce acoustic interference from suspended mate- rial associated with strong bottom currents. Mooring units consisted of a railroad wheel (227 kg), stainless steel air- craft cable (0.64 cm, 7 ? 19 strand), and subsurface and surface ?oats. Receivers were retrieved every three to six weeks and detection data (transmitter ID, date and time of detection) were downloaded directly to a shipboard com? puter by means of a VR1-PC cable interface (Vemco, Ltd.). Data for tautog released in fall 1998 were collected for the duration of the transmitter battery life. Data for tau- tog released in spring 1999 were collected until all VR1 receivers were permanently removed from each site. VR1 detections for each tautog were sorted into hourly bins and examined graphically. Because tautog are diurnally active and nocturnally quiescent (Olla et al., 1974; Arendt et al., in press), only daytime detection was used to determine site-utilization patterns. Tautog were considered resident at a particular site each day if they were detected at the same site throughout the day (morning, mid-day, evening). Total ?sh-days (sum of all days between date of ?rst and last detection for all ?sh) for each calendar season were classi?ed as 1) days when tautog were resident at the site of initial release, 2) days when tautog were detected at an alternative site, or 3) days when they were not detected at all. Site-utilization patterns of tautog were examined for each site in fall (from 9 Nov 98 to 20 Dec 98), winter (from 21 Dec 98 to 20 Mar 99), spring (from 21 Mar 99 to 20 Jun 99), and summer (from 21 Jun 99 to 9 Sep 99). To increase the probability that tautog would be re- ported as recaptured should recapture occur, transmitters were labeled with the specimen?s ID number, a $50 ?re- ward? notice, and a phone number. Tautog were tagged externally with a small, orange t-bar anchor tag (TBA2; Hallprint, Holden Hill, South Australia) used by the Vir? ginia Game Fish Tagging Program and with a larger, green t-bar tag (SHD-95; Floy Mfg., Seattle, WA) containing the specimen?s ID number, a $50 reward? notice, and a phone number. Internal and external reward notices were includ? ed because Szedlymayer (1997) had observed that internal reward notices persisted longer than external reward no? tices for red snapper (Lutjanus campechanus) in the Gulf of Mexcio, and that internal reward notices were noticed accidentally. In addition to distinct marking of each tau- tog, colorful reward posters were posted at over 40 mari? nas, boat ramps, and tackle shops in lower Chesapeake Bay and literature describing the project was mailed to over 5000 homes and businesses. Results Twenty-seven adult tautog (400?514 mm TL) were tagged with ultrasonic transmitters and released (16 in fall 1998, 11 in spring 1999) near Cape Charles, VA (Table 1). Four tautog were released at each of the four sites in fall 1998 and at the Coral Lump and Texeco Wreck in spring 1999. Two tautog were released at the Ridged Bottom and one tautog was released at the Airplane Wreck in spring 1999. Similar numbers of tautog were tagged and released at manmade (n=13) and natural bedform (n=14) sites. Eighty-one percent (n=22) of all tautog released were males; 19% were females. Thirteen percent (n=2) of tau- tog released in fall 1998 were female; 27% (n=3) of all tau- tog released in spring 1999 were female. Both female tau- tog released in fall 1998 (ID19, ID28) were released at the Texeco Wreck. One female tautog was released at the Tex? eco Wreck (ID37) and two female tautog were released at the Coral Lump (ID39, ID40) in spring 1999. Ninety-four percent (n=15 of 16) of tautog released in fall 1998 remained inshore within lower Chesapeake Bay during winter. Ninety-one percent (n=10 of 11) of tautog released in spring 1999 remained inshore within the Bay during summer. All tautog (n=14) released at natural sites remained in- shore and were detected only at their respective release sites. Tautog released at the Ridged Bottom and Coral Lump sites were detected 99% of ?sh-days in fall, 71?91% of ?sh-days in winter, 64?100% of days in spring, and 522 Fishery Bulletin 99(4) Table 1 Summary of ?sh-days for data from 27 adult tautog (400?514 mm TL) tagged and released with ultrasonic transmitters at four sites in lower Chesapeake Bay near Cape Charles, Virginia. Recaptured tautog are noted with an asterisk (*). Abbreviations for sites: CL = Coral Lump; TX = Texeco Wreck; RB = Ridged Bottom; AW = Airplane Wreck. Fish days ID Sex TL Site Date released At site Not detected At alternate site Total 1 M 432 CL 9 Nov 1998 174 8 0 182 18 406 CL 9 Nov 1998 155 19 0 174 19 495 TX 10 Nov 1998 58 105 2 165 20* 470 TX 10 Nov 1998 0 167 1 168 21 406 RB 10 Nov 1998 88 10 0 98 22 400 RB 10 Nov 1998 178 0 0 178 23 483 AW 13 Nov 1998 152 13 0 165 24 432 AW 13 Nov 1998 112 45 0 157 25 432 CL 3 Dec 1998 183 3 0 186 26 400 CL 3 Dec 1998 177 4 0 181 27 514 TX 4 Dec 1998 177 0 0 177 28 413 TX 4 Dec 1998 42 130 13 185 29* 400 AW 7 Dec 1998 147 14 1 162 30 419 AW 7 Dec 1998 46 21 0 67 31 445 RB 8 Dec 1998 144 24 0 168 32 419 RB 8 Dec 1998 88 39 0 127 33 406 TX 21 Apr 1999 0 136 6 141 34* 432 CL 28 May 1999 69 0 0 69 35 445 TX 28 May 1999 97 7 0 104 36 ? TX 28 May 1999 103 1 0 104 37* 445 TX 28 May 1999 99 5 0 104 38* 483 CL 7 Jun 1999 59 0 0 59 39* 483 CL 7 Jun 1999 59 0 0 59 40* 432 CL 7 Jun 1999 59 0 0 59 41 445 AW 7 Jun 1999 10 2 2 14 42* 406 RB 9 Jun 1999 58 0 0 58 43 M 406 RB 9 Jun 1999 56 2 0 58 M F M M M M M M M M F M M M M M M M M F M F F M M 98?100% of ?sh-days in summer (Fig. 2). Reduced detec? tion in winter and spring was partially attributed to two tautog (ID21, ID32) that were detected 46 d and 75 d less than the mean (175 d) for other tautog (n=12) released at the same time. To provide a more conservative estimate of site utilization, these tautog were listed as ?not detected? at these sites for these days. Eighty-?ve percent (n=11) of tautog released at man- made structures remained inshore and all but three of these were detected only at their respective release sites. Site utilization by tautog at the Texeco Wreck was low (34?71% of ?sh-days) in all seasons (Fig. 2). One tautog (ID20) released at the Texeco Wreck was only detected at the Texeco Wreck for three hours after being tagged and released in fall 1998. Two additional tautog (ID19, ID28) spent 64?70% of ?sh-days away from the Texeco Wreck in fall, winter, and spring, and a fourth tautog (ID33) spent 100% of ?sh-days away from the Texeco Wreck in spring and summer. One of these tautog (ID28) was detected at the Coral Lump for 6 days in January 1999 (VR1 receivers) and all three tautog were regularly detected with the VR60 receiver at a site 2 km south of the Texeco Wreck. Tautog released at the Airplane Wreck were resident 99% of ?sh- days in fall, 66% of ?sh-days in winter, and 58% of ?sh-days in spring (Fig. 2). Reduced detection in winter resulted partially from one tautog (ID30) being detected 108 days less than the mean (175 days) for other tautog (n=12) re- leased at the same time. To provide a more conservative estimate of site utilization, this tautog was listed as ?not detected? at the Airplane Wreck for these days. No sum? mer data were available for tautog at the Airplane Wreck because the single tautog (ID41) released there in spring 1999 was detected at this site for two days following re- lease, was later detected at the Texeco Wreck, and then was never detected again at any site. Tautog 41 was listed as ?not detected? at the Airplane Wreck from the time of Arendt et al.: Seasonal occurrence of site-utilization patterns of Tautoga onitis 523 Manmade structures Natural bedforms fall winter spring summer Pe rc e n ta ge o f ? sh -d ay s de te ct ed a t s ite o f r el ea se Figure 2 Seasonal site-utilization patterns of tautog released at manmade (Airplane Wreck and Texeco Wreck) and natural bedform (Ridged Bottom and Coral Lump) sites near Cape Charles, Virginia, in fall (9 Nov 98 to 20 Dec 98), winter (21 Dec 98 to 20 Mar 99), spring (21 Mar 99 to 20 Jun 99), and summer (21 Jun 99 to 9 Sep 99). Site-utilization patterns were greatest for tautog released at natural bedform sites. leaving this site until VR1 receivers were removed from this site, 112 d later. Eight tautog (27%) released in our study were subse? quently recaptured (Table 1). Two tautog (ID20, ID29) released in fall 1998 were recaptured (13%) away from release sites by commercial ?shermen in spring 1999. Tau- tog 20 was released at the Texeco Wreck on 10 November 1998 and either left this site the same day or its transmit? ter failed to transmit data. This tautog was subsequently recaptured 10.2 km northeast of the Texeco Wreck in a crab pot on 27 April 1999, 169 days later. Tautog 29 was ?rst caught at the Airplane Wreck on 13 November 1998 and held in a wire cage with several other tautog at the Airplane Wreck for ?ve days as part of a catch-release mortality study on tautog.3 After being released at the Air- plane Wreck on 18 November 1998, this tautog was re- captured at the Airplane Wreck on 7 December 1998 (19 d later) and ultrasonically tagged and released. Tautog 29 remained at the Airplane Wreck until 12 May 1999, then was recaptured in a gill net 2 km east of the Air- 3 Lucy, J. A., and M. D. Arendt. 1999. Exploratory ?eld evalua? tion of hook-release mortality in tautog (Tautoga onitis) in Lower Chesapeake Bay, Virginia. Rep. VMRC-99-10, 11 p. [Available from Marine Advisory Program, Virginia Institute of Marine Science, Gloucester Point, VA 23062.] plane Wreck on 19 May 1999. Recreational ?shermen re- captured six tautog released in spring 1999 (55%) at the same sites where these ?sh were released 114?211 d earli? er and 8?13 weeks after VR1 receivers were removed from sites. Discussion Tautog remained inshore within lower Chesapeake Bay during winter, at sustained water temperatures of 5?8?C (Arendt et al., in press). Although detected at these water temperatures, tautog overall were detected less than during other times of the year, most likely because tautog remained inactive and within structures for several days at a time (Arendt et al., in press). Inshore occurrence of tautog in winter has been observed in eastern Long Island Sound,4 Delaware Bay (Eklund and Targett, 1991), and lower Chesa- 4 Auster, P. J. 1989. Species pro?les: life histories and environ? mental requirements of coastal ?shes and invertebrates (North and Mid-Atlantic)?tautog and cunner. U.S. Fish and Wildlife Service Biological Report 82 (11.105). U.S. Army Corps of Engi? neers Rep. TR EL-82-4, 13 p. NOAA?s National Undersea Research Program, Univ. Connecticut at Avery Point, Groton, CT 06430. 524 Fishery Bulletin 99(4) peake Bay (Hostetter and Munroe, 1993). When water tem? peratures remains above 9?10?C,5 a viable winter inshore ?shery exists for tautog within lower Chesapeake Bay. Within the winter ?shery, inshore catches occur predomi? nantly in December and March, whereas offshore catches occur predominantly in January and February. Occurrence of an inshore winter ?shery for tautog in Virginia is unique within this species? geographic distribution. Tautog remained inshore during the summer at a maxi- mum sustained water temperature of 27?C (Arendt et al., in press). Summer residence data have been supported by direct underwater observations.6 Infrequent recreational catches of tautog in lower Chesapeake Bay during sum? mer have also been reported.2 Inshore, summer residence of tautog has been documented for Great South Bay, NY, when water temperatures were 19?24?C (Olla et al., 1974) and Narragansett Bay, RI, at maximum sustained water temperatures of 22?C.7 These ?ndings contradict reports from Virginia (Adams, 1993), New York (Briggs, 1969), and Rhode Island (Cooper, 1966) that adult tautog may move offshore to cooler water during summer. Tautog remained inshore during summer in the absence of blue mussels (Mytilus edulis), a primary food item of tautog in northern areas (Bigelow and Schroeder, 1953; Ol? la et al., 1974). In June 1998?99, using underwater video, otter trawl, and oyster dredge, we documented large clus? ters of live blue mussels at study sites and noted growth of mussels on VR1 mooring units. By July 1998?99, blue mussels were not present at any of these sites. Absence of mussels in July in both years was most likely due to le? thal effects of water temperatures ?27?C (Wells and Gray, 1960). Because blue mussels are not present in lower Chesa? peake Bay year round, the diet of tautog inhabiting lower Chesapeake Bay throughout the year may be more diverse than that of tautog in northern areas. Stomach contents from an ultrasonically tagged tautog recaptured in Octo? ber 1999 at the Ridged Bottom site consisted primarily of the bryozoan Alcyinidium verilli. At an arti?cial ?shing reef near Cape Charles, VA, tautog consumed a variety of crustaceans, shell?sh, bryozoans, and hydroids.8 Similar temporal distributions of blue mussels have been reported 5 White, G. G., J. E. Kirkley, and J. A. Lucy. 1997. Quantitative assessment of ?shing mortality for tautog (Tautoga onitis) in Virginia. Preliminary report, 54 p. Department of Fisheries Science and Marine Advisory Program, Virginia Institute of Marine Science, College of William and Mary, Gloucester Point, VA 23062. 6 Hager, C. 1999 (July). Personal communication of direct un? derwater observation of tautog at Plantation Light (3?8 m depth), 2 km southeast of Texeco Wreck study site. School of Marine Science, College of William and Mary, Virginia Institute of Marine Science, Gloucester Point, VA 23062. 7 Castro, K. 1999 (October). Personal communication of water temperature observation for Narragansett Bay. East Farm? Fisheries Center, Univ. Rhode Island, Kingston, RI 02881. 8 Feigenbaum, D., C. Blair, and A. J. Provenzano. 1985. Arti?? cial reef study?year II report. Virginia Marine Resources Com? mission rep. VMRC-83-1185-616, 57 p. VA Institute of Marine Science, Gloucester Point, VA 23062. in Delaware Bay, where diets of tautog subsequently shift towards alternative, less nutritious food items at times when blue mussels are unavailable.9 Year-round occurrence of adult tautog in Chesapeake Bay differs from seasonal (spring and fall) inshore occur? rence of adult tautog in Great South Bay, NY (Olla et al., 1974; Briggs, 1977), Narragansett Bay, RI (Cooper, 1966), and the Weweantic River Estuary, MA (Stolgitis, 1970). Year-round occurrence of ultrasonically tagged tautog was consistent with large-scale patterns of occurrence of tau- tog from conventionally tagged tautog (127?584 mm TL) in the Virginia Game Fish Tagging Program between 1995 and 1999.2,5 Of 563 recaptured tautog that were originally tagged in lower Chesapeake Bay, excluding Cape Charles, and adjacent coastal waters, 85% (n=476) were recaptured at the same sites where released 0?1214 d earlier, includ? ing 20 multiple recaptures of individuals at the same sites where originally released. High incidence of recaptures of tautog at the same sites where they were released oc? curred during all seasons. Only 5% of all recapture events involved movement (8?97 km) of tautog between Chesa? peake Bay and adjacent coastal waters. Daily detection patterns were almost always similar for both VR1 receivers at sites, indicating that tautog re? mained within the central signal reception area of both VR1 receivers and in the general vicinity of sites through- out the entire day. Tautog were generally not detected by VR1 receivers at night; however, tautog likely remained at sites throughout the night (Arendt et al., in press). Tau- tog were likely detected less often (or not at all) at night because of nocturnal quiescence in or near structure (Olla et al., 1974) and therefore were effectively out of range of VR1 receivers because of the presence of an acoustic barrier (Matthews, 1992; Pearcy, 1992; Bradbury et al., 1995,1997; Zeller, 1997). Featureless bottom topography, a known deterrent to emigration for large, temperate labrids (Notolabrus tetri? cus, N. fucicola, Pictilabrus laticlavius, Pseudolabrus psit? taculus) in Tasmania (Barrett, 1995), did not act as a de? terrent to emigration for tautog in lower Chesapeake Bay. Two tautog (ID20, ID28) released at the Texeco Wreck in fall 1998 traversed a wide (2-km), deep (37?40 m) mud- bottomed channel (Wright et al., 1987) on at least three occasions, and one of these tautog (ID20) was subsequent? ly recaptured. Two tautog (ID19, ID28) traveled between the Texeco Wreck and a site 2 km south of the Texeco Wreck on at least 12 occasions. A third tautog (ID33) left the Texeco Wreck almost immediately after being released and was subsequently detected (VR60 receiver) at this site throughout the remainder of our study. Movement by tautog was assumed to represent actual movement by tagged tautog as opposed to movement of a 9 Steimle, F., K. Foster, W. Muir, and B. Conlin. 1999. The diet of tautog collected on an arti?cial reef in Delaware Bay and interannual effects of prey availability (and notes on other tautog diet studies in the middle Atlantic Bight). First Biennial Conference on the biology of tautog and cunner, Mystic, CT, 30 November?1 December 1999. National Marine Fisheries Ser? vice, Highlands, NJ 07732. Arendt et al.: Seasonal occurrence of site-utilization patterns of Tautoga onitis 525 predator that may have preyed upon tagged tautog, even though these three tautog were never recaptured nor vi? sually observed after release. Adult tautog are very in- frequently preyed upon by sharks in Virginia (Gelsleich? ter et al., 1999); however, sharks are not likely present in Chesapeake Bay when water temperatures are 5?8?C. At these water temperatures, large striped bass (Morone saxatilis) pose the only possible predatory threat to tau- tog. A recent study on feeding habits of adult striped bass in Chesapeake Bay found no tautog in the stomachs of more than 2000 striped bass, many of which were collected from the Chesapeake Bay Bridge-Tunnel complex, a well- known ?shing area for adult tautog (Walters, 1999). All tautog detected or recaptured away from release sites were released at manmade sites, which also hap? pened to be the smallest sites. No information was avail- able regarding the origin of these manmade sites, but both have been in place for at least 20 years.10,11 Stone et al. (1979) concluded that arti?cial reefs reach a stable state after ?ve years. Benthic macrofauna collected at manmade sites during our study were similar to benthic macrofau? na collected at natural sites, suggesting that food may have been similar between manmade and natural sites. Given these observations, habitat size may be an impor? tant factor for adult tautog in determining the scale of lo? cal movements between adjacent habitats. Understanding the relationship between habitat size and site utilization warrants further investigation, especially with recent in- creased interest in the construction of arti?cial habitats for purposes of stock enhancement and enhanced ?shing opportunities for tautog. Sex ratio of female to male tautog in our study was heavily skewed (1:3.5) towards male tautog due to oppor? tunistic sampling, and the preponderance of male tautog likely contributed to the high levels of site utilization ob? served in our study. In laboratory settings, adult male tau- tog aggressively defend territories throughout most of the year (Olla et al., 1978, 1980) and only during the spawn? ing season are female tautog permitted to enter territo? ries (Olla and Samet, 1977; Olla et al., 1981). Overall ac? tivity, including male agonistic behavior, also decreases as water temperatures approach annual minimum and maxi- mum values (Olla et al., 1978, 1980). Although sample size in our study was too small to distinguish site-utilization patterns by sex, it is worth noting that both tautog that left the Texeco Wreck in Nov?Dec and that periodically re- turned to this site throughout the winter and spring were females. In contrast, during the spring spawning season, three females (one at Texeco Wreck, two at Coral Lump) remained at release sites throughout the spring?summer monitoring period and all three were subsequently recap? tured by recreational ?shermen at these same sites in the fall. More sex-speci?c data are needed to fully comprehend 10 Verry, S. 1998. Automated wreck and obstruction informa? tion system, special area report (37?00N?37?30N; 076?00W? 076?30W). NOAA/NOS,Hydrographic Services Branch/N/CS31, Silver Spring, MD 20910. 11 Jenrette, J. 1998. Personal commun. Captain, FV Bucca? neer, P.O. Box 149, Route 1108, Cape Charles, VA 23310. what role reproductive biology and social structure have on seasonal site-utilization patterns. Site-utilization patterns exhibited by ultrasonically tagged tautog were consistent with patterns reported for tautog released at these same sites from the Virginia Game Fish Tagging Program (VGFTP). Between April 1998 and October 1999, 40 tautog, tagged and released at these sites, were recaptured, including one tautog recap? tured twice at the same site. Six of eight (75%) tautog orig? inally released at the Texeco and Airplane Wrecks were re- captured away from these sites. Of these six tautog, three moved to the Coral Lump and Ridged Bottom and three moved to sites located 26.9 to 43.2 km away in lower Ches? apeake Bay. In contrast, 32 tautog tagged and released at the Coral Lump and Ridged Bottom sites were recaptured, all but two (which moved from the Ridged Bottom to the Coral Lump) were recaptured where released. One addi? tional ?sh moved to the Coral Lump from an arti?cial reef located 4 km to the northeast and within 2 km of where both tautog were recaptured by commercial ?shermen in spring 1999. Ultrasonically and conventionally tagged tautog re- leased near Cape Charles, VA, in lower Chesapeake Bay demonstrated high site utilization at and high site af?n? ity (returned to release sites after short emigration) for release sites. Extended residence by tautog at familiar sites during annual environmental extremes is considered more bene?cial than emigration to more optimal environ? mental conditions because residence at familiar sites re? duces the risk of not ?nding suitable shelter, food, mates, or of encountering predators (Olla et al., 1978). Although directed seasonal offshore movements were not observed in our study, movements between adjacent inshore loca? tions occurred several times, including movement to adja? cent locations during the periods of seasonal thermal ex? tremes. Understanding temporal and spatial utilization of habitats is an important ?rst step to identifying essential ?sh habitat and critical to evaluating and protecting ?sh? ery resources within Chesapeake Bay and elsewhere. Acknowledgments This research represents part of M. D. Arendt?s Master?s thesis; earlier drafts of this manuscript were reviewed by J. Hoenig, J. Musick, D. Evans, and W. DuPaul. J. Jenrette of the FV Bucaneer, C. Machen of the RV Langley, G. Pon? gonis, and J. Olney Jr. and VIMS divers (B. Gammisch, W. Reisner, T. Chisholm, and W. Stockhausen) provided valu? able ?eld assistance. We thank Vemco, Ltd., and Physical Sciences Department, VIMS, for assistance with equip? ment operation and deployment. We also thank J. Jen? rette and S. 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