Coastal cutthroat trout and estuary use in Puget Sound

For more information, view the original reports: The role of estuaries in the ecology of adult Pacific salmon and trout in Puget Sound and The role of estuaries in the ecology of juvenile Pacific salmon and trout in Puget Sound.

Overview

Coastal cutthroat trout, the subspecies native to Puget Sound, is related to rainbow/steelhead trout, the two species commonly co-occur in streams, and juveniles are difficult to distinguish by eye (Baumsteiger et al. 2005, Kennedy et al. 2009). Despite these similarities, their marine migrations differ greatly, as reviewed by Pearcy et al. (2018) and Losee et al. (2024). While steelhead smolts migrate rapidly to the open ocean, feed there for several years, and then return to spawn, cutthroat trout from Puget Sound streams typically spend less than a year at a time in marine waters and patrol the shorelines within about 20–30 km of their natal stream. Interestingly, populations on the coast (e.g., Salmon River, Oregon) include both estuarine residents and individuals that migrate into the ocean (Krentz 2007), where they occupy waters 30–50 km from shore (Pearcy et al. 1990). 

In Puget Sound’s marine waters, cutthroat trout caught by anglers must be released and in rivers they can be retained but, unlike salmon and steelhead, there are no catch records. There are no commercial fisheries for cutthroat trout, and thus none of the catch data like those of salmon and steelhead from which to infer migration patterns. Moreover, populations include anadromous and non-anadromous spawners (Claiborne et al. 2020), which further complicates analysis of their marine ecology. Individuals caught in marine waters are, by definition, anadromous; those caught in rivers may be so as well but one cannot be certain just by looking at them. Chemical analyses of their scales or otoliths are needed for a definitive answer. Populations consist of mixtures of anadromous and non-anadromous individuals rather than separate, isolated populations, based on work in Puget Sound (Claiborne et al. 2020), the lower Columbia River (Johnson et al. 2010), coastal Oregon (Tomasson 1978), and central Alaska (Saiget et al. 2007). 

Cutthroat trout migrations to Puget Sound overlap with those of the other salmonids but tend to be later, from April to June, and this is generally true of the species (Burns et al. 2021). We know this from catches of smolts in traps (Figure 1A). The timing and duration of marine residence varies considerably among populations and systems, as illustrated by different patterns in northern versus southern Puget Sound rivers (Figure 1B-D).

Adults

Despite the limited scientific information, anglers (Raymond 1996, Johnson 2004) and scientists (Johnston 1982) believe that cutthroat trout from the larger, northern Puget Sound rivers tend to stay near their natal rivers for the summer, return in the fall, over-winter in the river, spawn in the spring, and return to Puget Sound if they survive (Figure 1B). In contrast, populations from small streams tend to return in the winter, just prior to spawning, and return to marine waters shortly thereafter. This has been documented in southern Puget Sound (Losee et al. 2018), and Eld Inlet as representative of southern Puget Sound (Figure 1C). The small stream pattern was also reported in Big Beef Creek, on Hood Canal (Wenburg 1998) (Figure 1D), Snow and Salmon creeks, in Discovery Bay (Michael 1989), and Skookum Creek in southern Puget Sound (Losee et al. 2016).

In Puget Sound, most cutthroat trout do not move more than about 20–30 km from the natal streams, based on genetic assignment of fish to rivers of origin (Losee et al. 2017), and sonic tracking in Hood Canal (Goetz et al. 2013) and southern Puget Sound (Quinn et al. 2024). Consequently, there is variation in how long individuals stay in marine waters, but the component of populations that migrates to Puget Sound (Claiborne et al. 2020) relies heavily on estuaries and nearby nearshore areas, and for some cutthroat trout, estuaries are really their only marine habitat.

One further complication regarding the use of estuaries by coastal cutthroat trout is a possibility that they may move in and out of small streams in the fall to take advantage of drifting eggs from spawning salmon, prior the trout migration upstream to spawn. Such movement is inferred from the observation of cutthroat trout caught in marine waters that had consumed many salmon eggs (Jauquet 2002). Perhaps the eggs drifted down to the estuary and were eaten there; cutthroat trout in this area feed heavily on salmon eggs if they are available (Ellings 2003). It is also possible that the trout swam up to the spawning areas to feed on the eggs and then moved back into Puget Sound. Such entry into streams to feed on eggs is common in rainbow trout;  they move from lakes into streams in the fall to feed on salmon eggs (Arostegui and Quinn 2018), distinct from their spring spawning migrations.

In these habitats, cutthroat trout seem to favor gravel beaches with oysters and shell hash rather than lower-gradient sandy and muddy ones, and they can be very close to shore. Inexperienced anglers, intimidated by the size of Puget Sound, often wade as far from shore as they can and cast way out, until more savvy anglers point out that the cutthroat trout might be behind them. Sonic tracking of cutthroat trout with pressure sensitive transmitters indicated that the great majority of their time was spent 1–2 m below the surface (Quinn et al. 2024). Most of the detection patterns suggested that they were slowly cruising along the shoreline, but in some cases, they remained within a limited area (e.g., ca. 200–300 m along the shore) for hours or days (Quinn et al. 2024). 

While in marine waters, cutthroat trout have a varied diet that included fishes such as juvenile salmon, Pacific herring and shiner perch, and a variety of invertebrates (Jauquet 2002, Duffy and Beauchamp 2008). As with Chinook and coho salmon, cutthroat trout tend to rely more on fish as prey as they grow (Duffy and Beauchamp 2008), mirroring the pattern seen in Lake Washington (Nowak et al. 2004). Pacific herring comprised the greatest biomass of fish eaten by cutthroat trout in Puget Sound, but juvenile salmon were especially important from April to June. In terms of numbers, the trout ate primarily chum and pink salmon, but the larger-bodied juvenile Chinook salmon were more important in terms of biomass (Duffy and Beauchamp 2008).

Juveniles

Coastal cutthroat trout are commonly sympatric with rainbow/steelhead trout in smaller streams of Puget Sound and other regions where their ranges overlap, and naturally produced hybrids are not uncommon (Campton and Utter 1985, Baumsteiger et al. 2005, Kennedy et al. 2009). For example, steelhead (Moore et al. 2010a) and cutthroat trout smolts (Goetz et al. 2013) were trapped and implanted with sonic transmitters as they left Big Beef Creek, a small tributary of Hood Canal. Genetic analyses revealed that there were 52 cutthroat trout, 89 steelhead, and 42 hybrids (Moore et al. 2010b). The steelhead migrated rapidly, as is typical of the species in the Salish Sea, and the cutthroat trout limited their movements to Hood Canal itself, seldom moving more than about 10 km from the natal stream (Goetz et al. 2013). The movements of the hybrids were intermediate between the patterns of the pure species in terms of median residence time, time spent in the estuary, and sinuosity of the track (Moore et al. 2010b).

References

Arostegui, M. C. and T. P. Quinn. 2018. Trophic ecology of nonanadromous rainbow trout in a post-glacial lake system: partial convergence of adfluvial and fluvial forms. Canadian Journal of Zoology 96:818-827.

Baumsteiger, J., D. Hankin, and E. J. Loudenslager. 2005. Genetic analyses of juvenile steelhead, coastal cutthroat trout, and their hybrids differ substantially from field identifications. Transactions of the American Fisheries Society 134:829-840.

Burns, C. W., R. A. Ptolemy, and P. J. Tschaplinski. 2021. A synthesis of juvenile Coastal Cutthroat Trout emigration studies: considerations for researchers and resource managers. North American Journal of Fisheries Management 41:1522-1537.

Campton, D. E. and F. M. Utter. 1985. Natural hybridization between steelhead trout (Salmo gairdneri) and coastal cutthroat trout (Salmo clarki clarki) in two Puget Sound streams. Canadian Journal of Fisheries and Aquatic Sciences 42:110--119.

Claiborne, A. M., J. P. Losee, and J. A. Miller. 2020. Estimating migratory behavior and age for anadromous Coastal Cutthroat Trout Oncorhynchus clarkii clarkii in South Puget Sound: evaluation of approaches based on fish scales versus otoliths. North American Journal of Fisheries Management 40:1313-1323.

Duffy, E. J. and D. A. Beauchamp. 2008. Seasonal patterns of predation on juvenile Pacific salmon by anadromous cutthroat trout in Puget Sound. Transactions of the American Fisheries Society 137:165-181.

Ellings, C. S. 2003. The influence of spawning Pacific salmon (Oncorhynchus spp.) on the stable isotope composition, feeding behavior, and caloric intake of coastal cutthroat trout (O. clarki clarki). Evergreen State College, Olympia.

Goetz, F. A., B. Baker, T. Buehrens, and T. P. Quinn. 2013. Diversity of movements by individual anadromous coastal cutthroat trout in Hood Canal, Washington. Journal of Fish Biology 83:1161-1182.

Jauquet, J. M. 2002. Coastal cutthroat trout (Oncorhynchus clarki clarki) diet in south Puget Sound, Washington 1999 - 2002. Evergreen State College, Olympia.

Johnson, J. R., J. Baumsteiger, J. Zydlewski, J. M. Hudson, and W. Ardren. 2010. Evidence of panmixia between sympatric life history forms of coastal cutthroat trout in two lower Columbia River tributaries. North American Journal of Fisheries Management 30:691-701.

Johnson, L. 2004. Fly-fishing coastal cutthroat trout. Frank Amato Publishers, Portland.

Johnston, J. M. 1982. Life histories of anadromous cutthroat with emphasis on migratory behavior. Pages 123-127 in E. L. Brannon and E. O. Salo, editors. Proceedings of the Salmon and Trout Migratory Behavior Symposium. School of Fisheries, University of Washington, Seattle.

Kennedy, B. M., J. Baumsteiger, W. L. Gale, W. R. Ardren, and K. G. Ostrand. 2009. Morphological, physiological, and genetic techniques for improving field identification of steelhead, coastal cutthroat trout, and hybrid smolts. Marine and Coastal Fisheries 1:45-56.

Krentz, L. K. 2007. Habitat use, movement, and life history variation of coastal cutthroat trout Oncorhynchus clarki clarki in the Salmon River estuary, Oregon. Oregon State University, Corvallis.

Losee, J. P., A. M. Claiborne, P. D. Dionne, H. S. Faulkner, and T. R. Seamons. 2018. Size, age, growth and site fidelity of anadromous cutthroat trout Oncorhynchus clarkii clarkii in the Salish Sea. Journal of Fish Biology 93:978-987.

Losee, J. P., D. Palm, A. Claiborne, G. Madel, L. Persson, T. P. Quinn, T. Brodin, and G. Hellström. 2024. Anadromous trout from opposite sides of the globe: Biology, ocean ecology, and management of anadromous brown and cutthroat trout. Reviews in Fish Biology and Fisheries 34:461-490.

Losee, J. P., L. Phillips, and W. C. Young. 2016. Spawn timing and redd morphology of anadromous Coastal Cutthroat Trout Oncorhynchus clarkii clarkii in a tributary of south Puget Sound, Washington. North American Journal of Fisheries Management 36:375-384.

Losee, J. P., T. R. Seamons, and J. Jauquet. 2017. Migration patterns of anadromous Cutthroat Trout in South Puget Sound: A fisheries management perspective. Fisheries Research 187:218-225.

Michael, J. H., Jr. 1989. Life history of anadromous coastal cutthroat trout in Snow and Salmon creeks, Jefferson County, Washington, with implications for management. California Fish and Game 75:188-203.

Moore, M. E., B. A. Berejikian, and E. P. Tezak. 2010a. Early marine survival and behavior of steelhead smolts through Hood Canal and the Strait of Juan de Fuca. Transactions of the American Fisheries Society 139:49-61.

Moore, M. E., F. A. Goetz, D. M. Van Doornik, E. P. Tezak, T. P. Quinn, J. J. Reyes-Tomassini, and B. A. Berejikian. 2010b. Early marine migration patterns of wild coastal cutthroat trout (Oncorhynchus clarkii clarkii), steelhead trout (Oncorhynchus mykiss), and their hybrids. PLoS ONE 5:E12881.

Nowak, G. M., R. A. Tabor, E. J. Warner, K. L. Fresh, and T. P. Quinn. 2004. Ontogenetic shifts in habitat and diet of cutthroat trout in Lake Washington, Washington. North American Journal of Fisheries Management 24:624-635.

Pearcy, W. G., R. D. Brodeur, and J. P. Fisher. 1990. Distribution and biology of juvenile cutthroat trout Oncorhynchus clarki clarki and steelhead O. mykiss in coastal waters off Oregon and Washington. Fishery Bulletin 88:697-711.

Pearcy, W. G., R. D. Brodeur, S. M. McKinnell, and J. P. Losee. 2018. Ocean ecology of anadromous coastal cutthroat trout. Pages 905-930 in R. J. Beamish, editor. The Ocean Ecology of Pacific Salmon and Trout. American Fisheries Society, Bethesda, MD.

Quinn, T. P., M. C. Arostegui, C. S. Ellings, F. Goetz, J. P. Losee, J. M. Smith, and S. Zaniewski. 2024. Movements of anadromous coastal cutthroat trout (Oncorhynchus clarkii clarkii) in Puget Sound, Washington, USA. Environmental Biology of Fishes 107:319-334.

Raymond, S. 1996. The estuary flyfisher. Frank Amato Publishers, Portland.

Saiget, D. A., M. R. Sloat, and G. H. Reeves. 2007. Spawning and movement behavior of migratory coastal cutthroat trout on the western Copper River Delta, Alaska. North American Journal of Fisheries Management 27:1029-1040.

Tomasson, T. 1978. Age and growth of cutthroat trout, Salmo clarki clarki Richardson, in the Rogue River, Oregon. Oregon State University, Corvallis, OR.

Wenburg, J. K. 1998. Coastal cutthroat trout (Oncorhynchus clarki clarki): genetic population structure, migration patterns, and life history traits. University of Washington, Seattle.