sign in sign up
<<
Home , Bull trout, Hoh River, Queets River, Quinault River, Raft River (Washington)

North American Journal of Fisheries Management 25:1073±1081, 2005 ᭧ Copyright by the American Fisheries Society 2005 [Management Brief] DOI: 10.1577/M04-132.1

Extent of Anadromy in Bull and Implications for Conservation of a

SAMUEL J. BRENKMAN* AND STEPHEN C. CORBETT National Park Service, , 600 East Park Avenue, Port Angeles, 98362, USA

Abstract.ÐThe use of radiotelemetry revealed that ulations that spend their entire life cycle in fresh- adult bull trout con¯uentus moved between water (Goetz 1989; Swanberg 1997). freshwater and the Paci®c Ocean and between water- One critical unanswered question is the extent sheds along coastal Washington. Forty-seven of 82 radio-tagged bull trout implanted in the Hoh and to which bull trout move between freshwater and Kalaloch Creek basins were anadromous, and 23 ®sh marine environments. The extent of anadromy in were relocated in ®ve different up to 47 km bull trout remains uncertain primarily because ob- south of their tagging locations. Anadromous bull trout servations of native char have occurred in tidally typically entered the Hoh River from May to July, as- in¯uenced in regions of overlap with the cended as far as 78 km upstream to spawning areas by closely related and morphologically similar Dolly September, and returned to the ocean to overwinter. This Varden, and the two species have not been distin- is the ®rst study to verify that anadromy is a primary life history form in coastal bull trout. The presence of guished during those observations (McPhail and anadromy and the irregular periods of freshwater, es- Baxter 1996). To our knowledge, the only pub- tuarine, and marine residence observed in this study are lished evidence that bull trout occur in marine wa- consistent with observations reported for other Salveli- ters is based on museum specimens that were col- nus species. These results also demonstrate that anad- lected in nearshore marine environments of the romous bull trout inhabit a diverse range of estuarine, , Washington, and the Fraser River, freshwater, and marine habitats. Their af®nity to estu- (Cavendar 1978; Haas and and their observed temporal movements suggest that bull trout optimize winter refugia and forage op- McPhail 1991). portunities and are susceptible to incidental mortality in A prerequisite for successful conservation and gill-net and recreational ®sheries directed at other Paci®c recovery of bull trout populations is a more com- salmonids. An understanding of the extent of anadromy, plete understanding of life history or migratory sources of mortality, and diversity of habitats occupied forms and the extent of anadromy in bull trout. by bull trout is informative in the establishment of ap- The recognition of life history variability is im- propriate conservation and recovery strategies for this portant for maintaining biodiversity at the species species. level, and loss of such diversity may reduce the long-term ability of a species to adapt to changing The salmonid genus Salvelinus is known to ex- environments (Gresswell et al. 1994). It is known hibit diverse life histories that include anadromous that bull trout use an array of habitats in freshwater, and nonanadromous forms within a given species. but the degree to which they use marine habitats Salvelinus alpinus, S. fon- is unknown. In this study, we used radiotelemetry tinalis, and Dolly Varden S. malma all exhibit com- to determine movements of adult bull trout im- plex migratory patterns and are known to be anad- planted with radio transmitters in the Hoh River romous (White 1941; Armstrong 1974; Nordeng basin and Kalaloch Creek on the Olympic Pen- 1983). The bull trout S. con¯uentus, a species of insula, Washington (Figure 1). The primary ob- char that has declined in distribution and abun- jectives of the research were to (1) determine dance throughout its range, is primarily con®ned whether and to what extent bull trout exhibit an- to interior drainages throughout northwestern adromy and (2) characterize spatial and temporal and is known to migrate exten- movements of bull trout in the Hoh River basin. sively in freshwaters. Recent studies have neces- We also discuss conservation implications related sarily focused on life histories of bull trout pop- to the observed patterns of movement and existing recreational and commercial ®sheries in coastal Washington. * Corresponding author: sam࿞[email protected]. Study Area Received August 4, 2004; accepted November 24, 2004 The study area where bull trout were captured Published online July 20, 2005 and tagged included the Hoh River, South Fork

1073 1074 BRENKMAN AND CORBETT

FIGURE 1.ÐMap of the study area depicting the tagging locations (solid circles) of 82 adult bull trout, the locations of ®ve ®xed telemetry stations (open circles), and the extent of aerial telemetry surveys in the Hoh River (rkm 0±85) and South Fork Hoh River (rkm 0±23) and along the Paci®c coast from Cape Flattery to Grays Harbor, Washington.

Hoh River, and Kalaloch Creek. The Hoh River is sopium williamsoni, shorthead sculpin Cottus con- a glacial river that freely ¯ows in a westerly di- fusus, torrent sculpin C. rhotheus, reticulate scul- rection from its headwaters on the western slopes pin C. perplexus, coho kis- of the to its con¯uence with utch, spring±summer and fall O. the Paci®c Ocean (Figure 1). Sixty-®ve percent of tshawytscha, O. keta, pink salmon the Hoh River watershed (a 45-river-kilometer O. gorbuscha, summer and winter steelhead O. my- [rkm] reach) occurs in Olympic National Park and kiss, O. nerka, O. is managed as a natural area. The lower portion of clarkii, longnose dace Rhinichthys cataractae, and the river ¯ows through state, tribal, and private Paci®c lamprey Lampetra tridentata. In 1994, the lands. The river drains 644 km2 and descends in National Park Service and the Washington De- elevation from 1,216 m in the headwaters to its partment of Fish and Wildlife implemented catch- con¯uence with the ocean. River discharge in the and-release regulations for bull trout in recrea- Hoh River basin is strongly in¯uenced by rainfall tional ®sheries. in autumn and winter and glacial runoff in spring and summer. Methods The South Fork Hoh River is the major tributary Radiotelemetry procedures.ÐThis study was de- to the Hoh River. The South Fork Hoh River drains signed to track movements of adult bull trout 130 km2 and descends in elevation from 1,475 to (Ͼ400 mm in total length) ®tted with individually 128 m. Kalaloch Creek is located 17 km imme- coded radio transmitters (Model MCFT-3A, Lotek diately south of the Hoh River, drains 45 km2, Wireless). Species identi®cation of all tagged ®sh and descends in elevation from 320 m to its con- was con®rmed by microsatellite analysis con- ¯uence with the ocean (Figure 1). Stream dis- ducted by the Wild Trout and Salmon Genetics charge is in¯uenced by rainfall during winter Laboratory at the University of . Eighty- months. two bull trout were captured by angling and sur- In addition to bull trout, ®shes that inhabit the gically implanted with radio transmitters in the Hoh River basin include mountain white®sh Pro- Hoh River (n ϭ 58), South Fork Hoh River (n ϭ MANAGEMENT BRIEF 1075

15), and lower Kalaloch Creek (n ϭ 9) (Table 1). and Kalaloch Creek were bull trout and not Dolly Fish were captured from July 2002 to June 2003 Varden (P. Spruell, University of Montana, un- at various locations throughout the study area, in- published data). Radio-tagged bull trout averaged cluding rkm 0±3 in the Hoh River , rkm 507 mm in total length (range ϭ 404±695 mm), 27±65 in the Hoh River, rkm 0±11 in the South had a mean weight of 1.6 kg (range ϭ 0.8±3.6 kg), Fork Hoh River, and rkm 0±2 in Kalaloch Creek and were tracked for 10±20 months. (Figure 1). Captured bull trout were anesthetized Forty-seven of 82 (57%) bull trout moved from in a solution of tricaine methanesulfonate (80 mg freshwater to salt water and were considered to be per liter of water) for up to 7 min prior to deter- anadromous (Table 1). Of the remaining 35 ®sh mination of total length (mm) and weight (g). Each that were considered nonanadromous during their transmitter was tested for functionality before be- tracking histories, 21 moved exclusively in the ing inserted into the abdominal cavity in a manner Hoh River basin, three were considered dead and similar to that described by Ross and Kleiner the tags were later recovered, and 11 had tags that (1982). Radio transmitters were active for up to were assumed to have failed based on loss of con- 761 d, emitted a signal every 5 s, weighed 16 g tact. in air, and averaged less than 2% of ®sh weight. Upon completion of surgery, ®sh recovered in a Movements of Bull Trout Tagged in the Hoh cage in the river and were released within 20 min River Basin near their point of capture. All released ®sh ap- A total of 39 (of 73) bull trout that were tagged peared to exhibit normal behaviors upon release. in the Hoh River basin (including the Hoh River Radio signals did not transmit while ®sh occupied estuary and the South Fork Hoh River) moved salt water but resumed transmission when ®sh re- downstream and entered the Paci®c Ocean during entered an estuary and freshwater. various months. Some of these ®sh were relocated Tracking of ®sh.ÐThe tracking and relocation in coastal drainages located 5±47 km to the south of radio-tagged ®sh were accomplished by means of the Hoh River, including Cedar Creek (n ϭ 3 of ®ve ®xed stations distributed along riverbanks ®sh), Kalaloch Creek (n ϭ 1), the (n of the Hoh River basin (Figure 1). Additionally, ϭ 8), the (n ϭ 3), and the Quinault manual tracking was conducted weekly between River (n ϭ 1), during aerial and manual surveys the stations and in Kalaloch Creek. Each ®xed sta- (Figure 2; Table 1). One bull trout (®sh number tion was equipped with a radio receiver and two 23) moved from the Hoh River and later entered antennae designed to detect upstream and down- the Raft and Queets rivers (Table 1). Bull trout stream movements of individual ®sh. Presence of observed in coastal drainages were relocated in the radio-tagged ®sh at each ®xed station was recorded estuaries except for one individual that was de- and downloaded every 7±14 d. The station at the tected at rkm 16 in the Queets River. Hoh River mouth detected radio-tagged bull trout Of the 30 bull trout tagged in the Hoh River that moved to and from salt water (Figure 1). estuary, 21 moved upstream to various locations Aerial surveys were conducted up to three times from May to July (Figure 2). The longest upstream per month in a ®xed-wing airplane with an antenna spawning migration of ®sh implanted in the es- mounted to each wing strut. Fish were tracked tuary was 73 rkm (mean ϭ 35 rkm; SD ϭ 19 rkm). from an average altitude of 335 m throughout the Fish that were relocated in the upper Hoh River Hoh River, South Fork Hoh River, and the Paci®c basin had reached known spawning areas by Sep- coast from Cape Flattery to Grays Harbor (250 tember, and some ®sh moved downstream to the km), and were relocated in estuaries or freshwater estuary or ocean as early as December 2003 (Fig- portions of coastal drainages (Figure 1). The ®nal ure 2). Additionally, three ®sh moved to the ocean determination of ®sh location was based on the and were never detected again, and ®ve ®sh moved point where the peak signal occurred at the lowest into the ocean and were relocated in other coastal gain on the receiver. All detections were estimated drainages. The maximum distance traveled by to the nearest river kilometer from the ocean, and anadromous bull trout tagged in the Hoh River individual ®sh locations were mapped by use of basin was 172 km. ArcView software (Environmental Systems Re- search Institute 1996). Movements of Bull Trout Tagged in Results Kalaloch Creek Genetic analyses of microsatellites revealed that Eight of the nine bull trout that were tagged in all 82 radio-tagged ®sh from the Hoh River basin Kalaloch Creek moved downstream to the ocean 1076 BRENKMAN AND CORBETT

TABLE 1.ÐDates and general locations of tagging, migratory form, and dates of relocation in nearby watersheds for 82 radio-tagged bull trout tagged in the Hoh River, South Fork (SF) Hoh River, and Kalaloch Creek, Washington.

Fish tag number Date tagged Release locationa Migratory form Dates detected in other drainagesb 10 Jul 18, 2002 Hoh River Loss of contact 11 Aug 6, 2002 Hoh River Anadromous 12 Aug 9, 2002 Hoh River Anadromous RAF: 26 Feb 2004, 29 Mar 2004 13 Aug 9, 2002 Hoh River Loss of contact 14 Aug 9, 2002 Hoh River Anadromous CED: 3 Feb 2003 15 Aug 9, 2002 Hoh River Anadromous QUE: 25 Apr 2003±19 Mar 2004 16 Aug 21, 2002 Hoh River Loss of contact 17 Aug 21, 2002 Hoh River Anadromous 18 Sep 10, 2002 Hoh River Anadromous 19 Sep 11, 2002 Hoh River Anadromous 20 Sep 18, 2002 Hoh River Hoh basin only 21 Sep 19, 2002 Hoh River Anadromous 22 Sep 19, 2002 SF Hoh River Tag recovered 23 Sep 19, 2002 Hoh River Anadromous RAF: 25 Apr 2003; QUE: 9 May 2003, 3 Dec 2003, 21 Jan 2004 24 Sep 20, 2002 Hoh River Anadromous QUE: 3 Feb 2003±26 Feb 2004 25 Sep 20, 2002 Hoh River Anadromous 26 Sep 20, 2002 SF Hoh River Anadromous 27 Sep 20, 2002 SF Hoh River Hoh basin only 28 Sep 20, 2002 SF Hoh River Anadromous 29 Sep 20, 2002 SF Hoh River Anadromous 30 Sep 20, 2002 SF Hoh River Loss of contact 31 Sep 20, 2002 SF Hoh River Hoh basin only 32 Sep 20, 2002 SF Hoh River Anadromous 33 Sep 21, 2002 Hoh River Loss of contact 34 Sep 21, 2002 Hoh River Anadromous 35 Sep 26, 2002 Hoh River Loss of contact 36 Oct 10, 2002 Hoh River Anadromous 37 Oct 24, 2002 Hoh River Anadromous 38 Oct 24, 2002 Hoh River Anadromous 39 Mar 9, 2003 Hoh River Hoh basin only 40 Oct 24, 2002 Hoh River Hoh basin only 41 Oct 24, 2002 Hoh River Anadromous 42 Dec 20, 2002 Hoh River Anadromous KAL: 3 Feb 2003 43 Jan 15, 2003 Hoh River Anadromous CED: 24 Mar 2003 44 Feb 11, 2003 SF Hoh River Loss of contact 45 Feb 11, 2003 SF Hoh River Hoh basin only 46 Feb 14, 2003 SF Hoh River Anadromous RAF: 1 Jul 2003 47 Apr 3, 2003 Kalaloch Creek Anadromous HOH: 2 Jul 2003; KAL: 3 Dec 2003; QUE: 28 May 2004; RAF: 26 Jun 2004 48 Apr 3, 2003 Kalaloch Creek Anadromous QUE: 19 May 2003; HOH: 13 Jun 2003 49 Apr 3, 2003 Kalaloch Creek Anadromous RAF: 15 May 2003, 30 Sep 2003; QUE: 23 Jul 2003 50 Apr 8, 2003 Kalaloch Creek Anadromous HOH: 10 May 2003 51 Apr 8, 2003 Kalaloch Creek Anadromous HOH: 14 May 2003 52 Apr 8, 2003 Kalaloch Creek Tag recovered 53 Apr 14, 2003 Hoh estuary Hoh basin only 54 Apr 14, 2003 Hoh estuary Hoh basin only 55 Apr 15, 2003 Kalaloch Creek Anadromous HOH: 28 May 2003 56 Apr 15, 2003 Kalaloch Creek Anadromous QUI: 26 Jun 2004 57 Apr 15, 2003 Kalaloch Creek Anadromous HOH: 14 May 2003 58 Apr 16, 2003 SF Hoh River Hoh basin only 59 Apr 16, 2003 SF Hoh River Anadromous 60 Apr 16, 2003 SF Hoh River Hoh basin only 61 Apr 24, 2003 SF Hoh River Hoh basin only 62 Apr 30, 2003 Hoh estuary Loss of contact 63 Apr 30, 2003 Hoh estuary Hoh basin only 64 Apr 30, 2003 Hoh estuary Anadromous 65 Apr 30, 2003 Hoh estuary Loss of contact 66 May 1, 2003 Hoh estuary Loss of contact 67 May 1, 2003 Hoh estuary Hoh basin only 68 May 1, 2003 Hoh estuary Anadromous QUE: 19 May 2003 69 May 1, 2003 Hoh estuary Hoh basin only 70 May 1, 2003 Hoh estuary Anadromous CED: 9 May 2003 MANAGEMENT BRIEF 1077

TABLE 1.ÐContinued.

Fish tag number Date tagged Release locationa Migratory form Dates detected in other drainagesb 71 May 1, 2003 Hoh estuary Anadromous 72 May 1, 2003 Hoh estuary Hoh basin only 73 May 1, 2003 Hoh estuary Anadromous 74 May 1, 2003 Hoh estuary Hoh basin only 75 May 14, 2003 Hoh estuary Anadromous 76 May 14, 2003 Hoh estuary Anadromous 77 May 16, 2003 Hoh estuary Hoh basin only 78 May 16, 2003 Hoh estuary Hoh basin only 79 May 16, 2003 Hoh estuary Tag recovered 80 Jun 12, 2003 Hoh estuary Hoh basin only 81 Jun 12, 2003 Hoh estuary Anadromous QUE: 15 Jul 2003 82 Jun 13, 2003 Hoh estuary Anadromous QUI: 1 Jul 2003 83 Jun 13, 2003 Hoh estuary Anadromous 84 Jun 13, 2003 Hoh estuary Hoh basin only 85 Jun 23, 2003 Hoh estuary Loss of contact 86 Jun 23, 2003 Hoh estuary Anadromous 87 Jun 23, 2003 Hoh estuary Anadromous QUE: 23 Oct 2003, 12 Nov 2003; HOH: 2 May 2004 88 Jun 24, 2003 Hoh estuary Anadromous 89 Jun 24, 2003 Hoh estuary Anadromous QUE: 23 Oct 2003; HOH: 26 May 2004 90 Jun 24, 2003 Hoh River Hoh basin only 91 Jun 24, 2003 Hoh River Anadromous QUE: 1 Jul 2003; HOH: 6 Jul 2003 a Hoh Estuary ϭ rkm 0±3; Hoh River ϭ rkm 27±65; SF Hoh River ϭ rkm 0±11; Kalaloch Creek ϭ rkm 0±2. b Cedar Creek ϭ CED; Hoh River ϭ HOH; Kalaloch Creek ϭ KAL; Queets River ϭ QUE; ϭ QUI; Raft River ϭ RAF. by May 2003 and were initially relocated in the untagged bull trout (mean total length ϭ 584 mm; Hoh River (n ϭ 5), Queets River (n ϭ 1), or Raft range ϭ 280±760 mm) in legal winter steelhead River (n ϭ 1) (Figure 3). A total of three bull trout and spring Chinook salmon commercial ®sheries (®sh numbers 47±49) entered two or more river in the Hoh River from January to June 2002. There systems during their tracking histories (Table 1). is limited information on incidental capture or Additionally, one of the nine bull trout was killed, hooking mortality of bull trout in recreational ®sh- and its tag was recovered in Kalaloch Creek. eries in the study area. Bull trout tagged in Kalaloch Creek entered the Hoh River from May to July 2003, moved up- Discussion stream as far as 78 rkm (mean ϭ 69 rkm; SD ϭ Our ®ndings revealed that anadromy is a pri- 7 rkm) to known spawning areas by September mary life history form of bull trout in the study and returned to the ocean in December and March area. Movements of radio-tagged anadromous bull (Figure 3). One bull trout that was tagged in Ka- trout in this study and recent genetic studies dem- laloch Creek (®sh number 47) migrated to the up- onstrate that bull trout are the only native char to per Hoh River to spawn and returned to an area inhabit anadromous zones of the Hoh, Kalaloch, near its point of capture in December (Figure 3). Raft, Queets, and Quinault rivers along coastal That ®sh also was later detected in the Queets and Washington (Leary and Allendorf 1997; Spruell et Raft rivers (Table 1). al. 2003). In rivers where Dolly Varden occur, populations are con®ned to upper Interception of Bull Trout in Fisheries portions of the rivers and typically are land-locked Recreational angling and commercial gill-net (Cavendar 1978; Leary and Allendorf 1997). ®sheries directed at Paci®c salmon and steelhead The presence of anadromy in bull trout and the exist throughout most weeks of the year in portions irregular periods of freshwater, estuarine, and ma- of coastal rivers that are known to be inhabited by rine residence observed in this study are consistent radio-tagged bull trout. The highest number of with observations reported for other Salvelinus scheduled gill-net days per week typically occurs species (Armstrong 1974; Nordeng 1983; Randall in January and from September to December (Fig- et al. 1987). We recognize that our sampling design ure 4). Recreational ®shing effort also is generally focused on bull trout larger than 400 mm and there- highest during fall and winter months. We con- fore did not include resident forms that mature at ®rmed the incidental bycatch and mortality of 107 small sizes, if indeed such life history morphs exist 1078 BRENKMAN AND CORBETT

FIGURE 2.ÐMovements and relocations of radio-tagged adult bull trout that moved between freshwater and salt water and between watersheds along coastal Washington. In each panel, arrows within the map depict the movements of individual ®sh and the graph depicts the corresponding spatial and temporal movements in the Hoh River basin. Left panels show the downstream movements of anadromous bull trout (n ϭ 39) that emigrated from the Hoh River basin to the Paci®c Ocean and nearby coastal drainages; right panels illustrate the upstream movements of bull trout that were tagged in the Hoh River estuary. To facilitate graphical display of ®sh movements, only representative ®sh are included. in the study area. We believe that a high proportion capture locations also exclusively inhabited main- of the ®sh that were captured or relocated in the river corridors in freshwater, and no bull trout were Hoh River estuary and that moved exclusively in detected in any of the 18 tributary creeks of the freshwater were actually anadromous based on Hoh River basin. Additionally, anadromous bull their bright silver coloration, which is typical of trout typically spent the winter months in lower a marine-phase salmonid. Additionally, we spec- portions of streams or presumably overwintered in ulate that anadromous bull trout tolerate more rap- nearshore marine environments, similar to popu- id and frequent changes in salinity than do other lations throughout the Puget Sound, Washington Paci®c salmonids, based on observed movements (Goetz et al. 2004). The failure to relocate some among freshwater, estuarine, and marine environ- ®sh that entered the ocean during this study may ments. Future research could compare the salt- be attributed to the presence of alternate-year water acclimation time of bull trout with those of spawners, prolonged residence in salt water (where other Paci®c salmonids. radio tags did not transmit), or ocean mortality. Anadromous bull trout exhibited similar spatial The veri®cation that bull trout move between and temporal movements despite their different freshwater and salt water has implications for on- tagging locations. Fish tagged in Kalaloch Creek going conservation and recovery efforts in north- and the Hoh River estuary concurrently moved western North America. In interior portions of the upstream in June and July and accessed spawning bull trout's range, the apparent loss of migratory areas by September in the uppermost portion of forms of bull trout has been associated with habitat the Hoh River basin before returning downstream fragmentation and barriers (Nelson et al. 2002). (Figures 2, 3). Radio-tagged ®sh from different Relocation data revealed that anadromous bull MANAGEMENT BRIEF 1079

FIGURE 3.ÐMovements of adult bull trout that were radio-tagged in Kalaloch Creek, Washington, and subse- quently relocated. In each panel, arrows within the map depict the movements of individual ®sh and the graph depicts the corresponding spatial and temporal movements in the Hoh River basin. Left panels show the emigration of bull trout from Kalaloch Creek to the ocean (n ϭ 8 of 9 ®sh) and their uppermost relocations in adjacent watersheds; right panels depict the migration of one bull trout from Kalaloch Creek to the upper Hoh River and then back to an area near its point of capture. The ®sh in right panels was later relocated in the Queets and Raft rivers. trout moved long distances to access nearby wa- primary factors attributed to the decline of pota- tersheds and that the expression of anadromy may modromous bull trout were habitat degradation, be critical in the recolonization of extant habitats. dams, irrigation projects, and over®shing by rec- Our results also demonstrate that anadromous bull reational anglers (Markle 1992; Ratliff and Howell trout inhabit a diverse range of estuarine, fresh- 1992; Leary et al. 1993; Rieman and McIntyre water, and marine habitats. Ongoing conservation 1993). However, there is little information regard- and recovery efforts should consider the impor- ing the extent of bycatch and incidental mortality tance of the lower portions of watersheds like the of anadromous bull trout in commercial and rec- Raft River and Kalaloch Creek even though these reational ®sheries. systems do not support bull trout spawning. The Our ®ndings indicate that bull trout are inter- use of ®ve different estuaries by adult bull trout cepted during upstream or downstream movements highlights the importance of these areas during to and from salt water in commercial ®sheries that most months of the year. We speculate that these are directed at other Paci®c salmonids. The extent, coastal watersheds serve as refugia from high win- seasonal variation, and overall effect of incidental ter ¯ows in the Hoh River and as important forage mortality of bull trout at the population level re- areas that confer growth and reproductive advan- main unknown. However, bull trout are vulnerable tages to bull trout. to incidental bycatch for the following reasons: (1) The veri®cation of anadromy in this study raises the timing of movements of radio-tagged ®sh be- questions regarding the fate of bull trout in rivers tween freshwater and salt water coincides with the where commercial gill-net and recreational ®sh- harvest seasons for Paci®c salmon and steelhead eries exist for Paci®c salmon and steelhead. The (Figure 4); (2) bull trout possess an af®nity for 1080 BRENKMAN AND CORBETT

FIGURE 4.ÐScheduled number of gill-net days by statistical week for spring Chinook salmon (May±August), fall coho and Chinook salmon (September±January), and winter steelhead (November±April) ®sheries in the Hoh, Queets, and Quinault rivers, Washington (Washington Department of Fish and Wildlife, unpublished data). Radio- tagged anadromous bull trout were observed in each of these rivers. one or more estuaries where ®sheries exist in the Boetsch for their assistance with data management lower portion of the Hoh, Queets, and Quinault and generation of ®gures. We also thank Jason rivers (Table 1); and (3) the species' longevity and Dunham, Gary Larson, Bruce Rieman, and one ability to spawn repeatedly (Goetz 1989) increase anonymous reviewer for their helpful comments the number of possible encounters with ®sheries. on an earlier version of this manuscript. This re- Life history traits such as slow growth, low fe- search was funded by the National Park Service's cundity, and high catchability also render bull trout Natural Resource Preservation Project. Additional susceptible to overharvest in recreational ®sheries technical and ®eld support and funding were pro- (Post et al. 2003). Overall, an understanding of vided by the Washington Department of Fish and temporal migratory patterns, diversity of habitats Wildlife (Montesano and Olympia) and the U.S. occupied, and the relative in¯uence of recreational Fish and Wildlife Service (Lacey, Washington). and commercial ®sheries on anadromous bull trout Reference to trade names does not imply endorse- will be informative in the establishment of appro- ment by the U.S. Government. priate conservation and recovery strategies for this species. References

Acknowledgments Armstrong, R. H. 1974. Migration of anadromous Dolly Varden (Salvelinus malma) in southeastern Alaska. Thanks to Phil Kennedy, John Meyer, Jeremiah Journal of the Fisheries Research Board of Canada Nelson, and numerous biologists who assisted with 31:435±444. the ®eldwork. We thank Katherine Beirne and John Cavendar, T. M. 1978. and distribution of MANAGEMENT BRIEF 1081

bull trout, Salvelinus con¯uentus (Suckley), from the velinus con¯uentus, and implications for conserva- American Northwest. Fish and Game 64: tion. Environmental Biology of Fishes 64:321±332. 139±174. Nordeng, H. 1983. Solution to the ``charr problem'' Environmental Systems Research Institute. 1996. based on Arctic char (Salvelinus alpinus) in Norway. ArcView GIS: the geographic information system Canadian Journal of Fisheries and Aquatic Sciences for everyone. Environmental Systems Research In- 40:1372±1387. stitute, Redlands, California. Post, J. R., C. Mushens, A. Paul, and M. Sullivan. 2003. Goetz, F. A. 1989. Biology of the bull trout, Salvelinus Assessment of alternative harvest regulations for con¯uentus: a literature review. U.S. Forest Service, sustaining recreational ®sheries: model develop- Eugene, . ment and application to bull trout. North American Goetz, F. A., E. Jeanes, and E. Beamer. 2004. Bull trout Journal of Fisheries Management 23:22±34. in the nearshore. U.S. Army Corps of Engineers, Randall, R. G., M. G. Healey, and J. B. Dempsey. 1987. Preliminary Draft, Seattle. Variability in length of freshwater residence of Gresswell, R. E., W. J. Liss, and G. L. Larson. 1994. salmon, trout, and char. Pages 27±41 in M. J. Dad- Life history organization of Yellowstone cutthroat swell, R. J. Klauda, C. M. Mof®tt, R. L. Saunders, trout (Oncorhynchus clarki bouvieri) in Yellowstone R. A. Rulifson, and J. E. Cooper, editors. Common Lake. Canadian Journal of Fisheries and Aquatic strategies of anadromous and catadromous ®shes. Sciences 51(Supplement 1):298±309. American Fisheries Society, Symposium 1, Bethes- Haas, G. R., and J. D. McPhail. 1991. Systematics and da, Maryland. distribution of Dolly Varden (Salvelinus malma) and Ratliff, D. E., and P. J. Howell. 1992. The status of bull bull trout (Salvelinus con¯uentus) in North America. trout populations in Oregon. Pages 10±17 in P. J . Canadian Journal of Fisheries and Aquatic Sciences Howell and D. V. Buchanan, editors. Proceedings 48:2191±2211. of the Gearhart Mountain Bull Trout Workshop. Leary, R. F., F. W. Allendorf, and S. H. Forbes. 1993. American Fisheries Society, Oregon Chapter, Cor- Conservation genetics of bull trout in the Columbia vallis. and drainages. Conservation Biology Rieman, B. E., and J. D. McIntyre. 1993. Demographic 7:856±865. and habitat requirements for conservation of bull Leary, R. F., and F. W. Allendorf. 1997. Genetic con- trout. U.S. Forest Service, General Technical Report ®rmation of sympatric bull trout and Dolly Varden INT-302, Ogden, Utah. in western Washington. Transactions of the Amer- Ross, M. J., and C. F. Kleiner. 1982. Shielded-needle ican Fisheries Society 126:715±720. technique for surgically implanting radio-frequency Markle, D. F. 1992. Evidence of bull trout ϫ brook trout transmitters in ®sh. Progressive Fish-Culturist 44: hybrids in Oregon. Pages 58±67 in P. J. Howell and 41±43. D. V. Buchanan, editors. Proceedings of the Gear- Spruell, P., A. R. Hemmingsen, P. J. Howell, N. Kanda, hart Mountain Bull Trout Workshop. American and F. W. Allendorf. 2003. Conservation genetics Fisheries Society, Oregon Chapter, Corvallis. of bull trout: geographic distribution of variation at McPhail, J. D., and J. S. Baxter. 1996. A review of bull microsatellite loci. Conservation Genetics 4:17±29. trout (Salvelinus con¯uentus) life history and habitat Swanberg, T. R. 1997. Movements of and habitat use use in relation to compensation and improvement by ¯uvial bull trout in the Blackfoot River, Mon- opportunities. Department of Zoology, University tana. Transactions of the American Fisheries So- of British Columbia. Fisheries Management Report ciety 126:735±746. 104, Vancouver. White, H. C. 1941. Migrating behaviour of sea-running Nelson, M. L., T. E. McMahon, and R. F. Thurow. 2002. Salvelinus fontinalis. Journal of the Fisheries Re- Decline of the migratory form in bull charr, Sal- search Board of Canada 5(3):258±264.