The behavior and ecology of Pacific salmon and trout

“Many Pacific salmon (Oncorhynchus spp.) populations undertake arduous, energetically expensive reproductive migrations of greater than a 1000 km with elevation gains of over 1000 m which require several weeks to complete (Groot and Margolis 1991; Quinn 2005).”

“Just after absorbing the yolk sack nutrients, sockeye salmon juveniles start migrating from the spawning to the foraging areas in the ocean or lakes (Groot & Margolis, 1991; Quinn, 2018).”

“These changes benefit water quality important to salmonids by reducing the influx of sediment and decreasing stream temperature (Waters 1995, Poole and Berman 2001, Quinn 2005).”

“As they swim out into the Pacific Ocean, juvenile salmon access rich ocean nutrients, enabling them to grow and mature (Quinn 2005).”

“Salmonid life histories exhibit a behavioral adaptation to early freshwater entry timing many months prior to spawning so increase the chances of entering habitats that are otherwise blocked by low seasonal flows (Quinn 2005).”

“Territoriality, or the tendency for fish to remain in an isolated and restricted area, is expressed by juvenile salmonids rearing in freshwater streams (Quinn 2005) and the segregated spatial patterning (SI Appendix B in Huber 2018) and relatively small core areas (Table 1) of individual fish suggests that territorial…”

“other salmonids (Quinn 2005), and the regular use of different estuaries by individuals 655 during the summer documented by our telemetry work (Moore et al.”

“…on growth might be particularly strong in steelhead because hatchery fish are raised for a single year in freshwater (in captivity) before smolt outmigration, whereas natural-origin fish spend 1– 3 years in freshwater before migrating, with the vast majority spending at least 2 years (Quinn 2005).”

“On a larger scale, the genetic relationships among Chinook Salmon populations reflect rangewide patterns of recolonization of freshwater habitats in the 10,000 years since the last glacial epoch, overlaid with more recent gene flow within smaller geographic regions and natural selection (Quinn 2005; Beacham et al. 200…”

“In large lacustrine–fluviatile systems, the presence of such populations is quite common (Karpenko, 1998; Quinn, 2005; Shuntov and Temnykh, 2008).”

“Discharge is an important organizing factor for fish because the fish can migrate and adapt in response to changes in Q and stage-related habitat availability (Graybill 1974; Milner and Bailey 1989; Ward 1989; Ward and Stanford 1995; Quinn 2005; Tockner et al. 2006; Pess 2009).”

“Adult returns of fish transplanted in 2005 and 2006 were not observed at the weir in 2007 or 2008, and given the very low survivorship that characterizes salmonid populations in marine environments (Quinn 2005) it would be remarkable to observe any adult returns of these transplanted trout.”

“While the smolt lifestage is that which migrates to the ocean, earlier ontogenetic stages can also move downstream from natal reaches in the upper river to feed and grow in the warmer, more productive downstream reaches (Gaines & Martin, 2002; Quinn, 2018).”

“Homing to natal sites is a fundamental life-history trait in anad-romous salmonids, facilitating local adaptation to specific environmental conditions (Fraser et al. 2011; Hendry et al. 2003; Keefer and Caudill 2014; Quinn 2007).”

“…where fry will spend one to two years residing in lakes following emergence (Foerster 1968; Braun, Reynolds, and Jonsson 2011), then migrate to the ocean where they will spend the next one to three years before returning to spawn in the tributaries or outlets of their natal lakes (Quinn 2018).”

“Indeed, if lake trout in the present study spawned at the same time as Arctic char (October – November) or as temperate lake trout, they could hatch as late as July, limiting their window for summer growth (Quinn, 2005; Skoglund et al., 2012).”

“…both grow to similar sizes they have different life histories affecting growth rate; lake trout is iteroparous with a lifespan of 25 + years, while Chinook salmon is semelparous and lives 3–4 years (Jacobs et al., 2013 ; Mumby et al., 2018; Quinn, 2005; Stewart, Kitchell, & Crowder, 1983 ).”

“The timing of return to freshwaters is variable among and within native populations (Ricker 1972; Healey 1990; Quinn 2005; Keefer et al. 2008), but two distinct groups referred to as Spring and Fall Chinook salmon runs generally describe the phenology of the adult spawning migration of this species…”

“InMay–April, the young ofOncorhynchus gorbuscha have transformed into saline-tolerant smolts that migrate downstream to estuaries and coastal waters, where they remain for several months for feeding (Heard, 1991; Quinn, 2005; Gallagher et al., 2012; Paulsen et al., 2022).”

“…comprised of two major migratory forms: anadromous sockeye salmon (hereafter referred to as “sockeye salmon”) and nonanadromous, resident kokanee (hereafter referred to as “kokanee”), which are further subdivided into ecologically divergent reproductive ecotypes (Quinn, 2005; Taylor et al., 1996).”

“…activities (e.g. elephant seals and whales moving to high latitudes to exploit abundant food resources; Le Boeuf et al. 2000; Bailey et al. 2009; Durban & Pitman 2012) and/or to complete their lifecycle (e.g. sea turtles or salmons that return to their natal area to breed; Miller 1997; Quinn 2018).”

“…spawn timing may be related to variation in spawning habitat water temperatures (Beechie et al., 2008); earlier spawning tends to occur in cold streams, while populations from warmer streams tend to spawn later because of the differences in accumulated thermal degrees eggs experience (Quinn, 2018).”

“These numerical increases were a direct result of recolonization, population growth, and spatial spread above the dam by Coho Salmon (Kiffney et al. 2009, Pess et al. 2011, Burton et al. 2013, Anderson et al. 2015), a species more productive than resident salmonids (Quinn 2005).”

“As anadromous fish, salmon develop in freshwater systems, migrate to the ocean where they complete growth and development, and return to their natal streams to spawn [10].”

“Given that a variety of physical, biological and social factors are known to drive salmonid outmigration from natal habitats (Quinn 2011; Zeug et al. 2014; Sturrock et al. 2015), further study on Clear Lake hitch is warranted because it is likely to generate information useful for guiding stream habitat restoration.”

“focus of conservation and sustainable management efforts throughout their range (Quinn, 2005).”

“Temperature is a key environmental factor, regulating biological processes such as metabolism and physiology, the timing of life history events and community composition and structure (Beschta et al. 1987; Montgomery and Buffington 1998; Quinn 2011).”

“In comparison, Quinn (2005), drawing from multiple sources from other rivers including populations in undammed rivers, estimated an average C. salmon egg-to-smolt survival of 10.4%.”

“Salmonid fishes show strong homing instincts, wherein 95–99% of fish that survive to adulthood return to their natal breeding site, leading to populations with a variety of local adaptations to features of their breeding ground (Taylor 1991; Quinn 2005).”

“Before river impoundment began, this behavior may have supported individual survival and population persistence by allowing steelhead to find and use temperature refugia or other habitat suitable for spawning [34].”

“In contrast, males do not display nest defense behavior and are more mobile within spawning grounds (Shardlow et al. 1986; Quinn 2005; Murdoch et al. 2010).”

“However, small, non-anadromous females (e.g., kokanee) typically sacrifice primarily fecundity but also egg size, and their eggs are smaller than those of anadromous females (Wood and Foote 1990, 1996; Quinn 2005).”

“A considerable amount research has accumulated about the ecology of Pacific salmon (see Quinn 2005), but a comprehensive interecosystem study of their ecological role has yet to be done.”

“Run timing in salmon can be remarkably consistent across years within a single population, yet incredibly variable across populations and species ( 26 ).”

“For riverine fishes, tributary streams often provide important spawning and juvenile rearing habitat (Healy & Smith, 2023; Schlosser, 1991), allowing for natal site fidelity that can generate local adaptation and response diversity (Braun et al., 2016; Quinn, 2018).”

“Salmonids, for example, are thought to use a number of different compasses during long-distance migration, including the sun, geomagnetic fields and maybe even polarised light (Naisbett-Jones and Lohmann, 2022; Quinn, 2005).”

“…examples include the annual pole-to-pole migration of Arctic terns [5, 6] and sooty shearwaters [7], that achieve flight distances spanning thousands of kilometers or the precise navigation of anadromous salmon, swimming from the open ocean to return to their natal spawning grounds [8, 9].”

“Pink salmon have a 2-year lifes - pan, during which they spend about 1 year at sea before returning to native rivers to spawn at age 2 in odd or even years (Quinn, 2005 ).”

“Juvenile Chinook salmon typically rear for a year in large rivers that fl ow with greater velocities than the smaller, slower, streams that support coho salmon for up to 2 years before their seaward migrations (Healey, 1991; Quinn, 2018; Sandercock, 1991).”

“…before attacking with their teeth, akin to behavior documented in better studied groups such as salmons and South American knifefishes (Evans et al., 2018; Quinn, 2018) and even mammals (Barrette, 1977; Plavcan et al., 1995) and frogs (Emerson, 1994) that bite conspecifics to establish dominance.”

“Many of these varied phenotypes for Pacific salmon (Oncorhynchus spp.) are described by Quinn (2018).”

“For Chinook salmon which spend up to 5 years at sea (Quinn 2005), hatchery-specific smolt-to-adult survival rates through outmigration year 2008 were available from Ruff et al. (2017) and further updates through out-migration year 2011 were provided by the Washington Department of Fish and…”

“Estuarine habitats support two common life history types observed for sub-yearling Chinook salmon: fry migrants and parr migrants (Healy 1982, Quinn 2018).”

“First, the high density of salmon in the river raises the costs of competing for limited food resources and salmon may restrict their feeding and perform the river migration on a limited energy budget [50, 74]; but see [75] for evidence that smolt feeding increases in the lower Columbia River.”

“Salmonids having anadromous lifecycle spend most of their life at sea but the reproduction process occurs in fresh water and many of them die after spawning [7].”

“In the opinion of some authors [4, 5], pink salmon has on average less strict homing, or the “home” instinct (and, accordingly, higher straying, or dispersion, upon return to spawning), than other salmon species.”

“Conserv Biol 25, 932–944 [21] Quinn TP, 2011 The Behavior and Ecology of Pacific Salmon and Trout.”

“Chinook salmon (Oncorhynchus tshawytscha) is an economically, ecologically, and culturally important anadromous semelparous species that spawns in most rivers of western North America discharging into the Pacific Ocean from San Francisco, California to Alaska (Quinn 2005).”

“For example, in a caging experiment, fish remained in a cage against water flow, but naturally swimming salmon might actually be carried with the flow or actively swim downstream [26].”

“During this time, juvenile trout experience high levels of mortality consistent with other salmonids (> 90%, Quinn, 2005).”

“Variation in life-history traits contributes to fitness and population productivity in salmonids (Quinn 2005; Koch and Narum 2021).”

“In addition, salmonid populations in the Columbia River system were likely decimated by floods from Glacial Lake Missoula in the Late Pleistocene (Alt 2001; Quinn 2005, 318; also see Plew and Guinn 2015) and Pluvial Lake Bonneville (ca. 14,500 cal yr BP; Jarrett and Malde 1987).”

“Among Oncorhynchus spp ., differences in migratory size and timing can be the result of variability in freshwater conditions between tributaries or stream reaches, despite common downstream conditions [10,49].”

“After spawning, some Steelhead also migrate back downstream as kelts (post-spawn adults that migrate back out to the ocean), as Steelhead are the only iteroparous Pacific salmon (Quinn 2005).”

“Similarly, anadromous species gain reproductive advantages through freshwater spawning, where more stable hydrological conditions and reduced egg/larval predation risk enhance offspring survival (McDowall 1997; Quinn 2018).”

“Rainbow trout in the current study did attain an older maximum age and larger maximum weight compared to the 1970s, which could have implications for reproduction potential in the tributaries (Quinn, 2005).”

“Downstream migration in smolts is active, and feeding opportunities are uncertain, thus there is speculation that smolts rely largely on stored energy from the rearing habitat to fuel migration to marine environments (Stefansson et al. , 2003; Quinn, 2005; Clark et al. , 2016).”

“Homing results in reproductive isolation and reduced gene flow among populations, leading to the evolution of myriad population-specific differences in phenotypic traits (Taylor, 1991; Fraser et al., 2011; Quinn, 2018) and independent population dynamics.”

“Males generally occur in both anadromous and resident forms, and growth in early life is commonly associated with a diversification of life-history forms; larger males tend to be the resident form (Utoh, 1976; Rowe & Thorpe, 1990; Yamamoto & Nakano, 1996; Quinn 2005).”

“These species also vary in their life histories because coho are almost always anadromous, while some cutthroat trout populations reside full time in fresh water (Goetz et al. 2013, Parkinson et al. 2017, Losee et al. 2018, Quinn 2018).”

“Depending on the strength and direction of intersexual and intertactical genetic correlations, antagonistic selection between sexes and tactics could theoretically (1) maintain variation for ARTs if traits that make a low fitness male tactic also make a high fitness female, (2) reduce population growth rate if traits…”

“However, they are small bodied; a commercial fishery sample (n = 600 measured for length and 58 for length and mass, data from Alaska Department of Fish and Game) averaged only 1.17 kg—less than half the average mass of the species (Quinn 2018).”

“Salmonids generally spawn in either fall or spring (Quinn 2018).”

“A rapid migration to reach Harrison Lake is more common for the Weaver population when fry reach around 32 mg. Faster migrating Chilko fry can reach Chilko Lake at around 22 mg, but some fry extend their migration into June and arrive at the lake much larger (Brannon 1972).”

“24 mortality rates are lower at sea (Garcia de Leaniz et al., 2007; Quinn, 2005).”

“Anadromous salmonid hatchery programs rely on the homing mechanism of salmon and steelhead (Hendry et al. 2004, Quinn 2005) whereby adults return to their hatchery of origin or a juvenile release site (i.e., acclimation site).”

“Salmonids have been widely introduced outside their native ranges and have successfully established both naturalized anadromous and resident populations worldwide (Quinn, 2005).”

“…distribution, downstream migration, phenotypic diversity, Ozernaya River, Lake Kurilskoye DOI: 10.1134/S0032945217060091 Sockeye salmon Oncorhynchus nerka is the only species of Pacific salmon specialized on reproduction in lake and river systems (Quinn, 2005; Bugaev and Kirichenko, 2008).”