The behavior and ecology of Pacific salmon and trout

“Anadromy and homing are behaviourally coupled in sea trout and other salmonids (McDowall 2001), and both are thought to reflect and promote local adaptation to environmental conditions (Quinn 2005).”

“The importance of olfactory function to salmon homing has been reviewed in many behavioral, electrophysiological, and neurobiological studies [2-6].”

“…history diversity is most frequently associated with variation in the age, timing, and size of transitions between life stages (i.e., smolting and maturation; Quinn 2007 ), which has been shown to stabilize population dynamics via port-folio effects (Hilborn et al. 2003 , Schindler et al. 2010 ).”

“Fourth, Pink Salmon have relatively high natural stray rates among populations, likely due to a combination of the lack of overlapping age cohorts and reduced environmental variation among spawning sites, particularly for intertidal spawners (Quinn, 2018; Salmenkova, 2017).”

“The age and size of individuals undergoing the smoltification process can vary within and across populations (Groot and Margolis 1991, Quinn 2005), and life-history expression may respond to shifts in climate conditions (Crozier et al. 2008).”

“It was thus assumed that all fish follow this “typical” coho life-cycle and return to their natal rivers at age three (Coronado & Hilborn, 1998; Quinn, 2005), which implicitly assumes that the number of fish returning after a single summer (early maturing males known as jacks) or spending additional years in the ocean…”

“…for distinct ocean age-classes was based on the observation that duration in the ocean is the primary determinant of size in maturing sockeye salmon (Quinn 2005) and findings by Kendall et al. (2009) indicating that size is a key determinant of selectivity in the gillnet gear used in Bristol Bay.”

“1–2 years prior to seaward migration as smolts (Quinn 2005).”

“This pattern of spawning activity likely reflects the low fecundity of potamodromous trout compared with semelparous anadromous salmonids (Quinn 2005).”

“The regular patterns of salmonmigration and spawning timing are an integral feature of their basic biology (Ricker 1972; Quinn 2005).”

“Adult Coho Salmon (Oncorhynchus kisutch) and Chum Salmon (Oncorhynchus keta) were obtained from two hatcheries located on the east coast of Vancouver Island, British Columbia (Puntledge Hatchery and Big Qualicum Hatchery).”

“…success of pink salmon may exceed Poisson (over-dispersed) because competition for spawning areas (i.e., density dependence) can lead to redd superimposition (i.e. destruction of spawning redds and reproductive failure of some adults; Groot and Margolis 1991; Fukushima et al. 1998; Quinn 2005).”

“First, Pacific salmon are semelparous, completing their life cycle and inevitably dying after reentering freshwater to spawn (Quinn 2005).”

“J. Chamberlin NOAA-Fisheries, Northwest Fishery Science Center, 2727 Montlake Blvd. East, Seattle, WA 98112, USA 1989; Weitkamp and Neely 2002; Weitkamp 2010; reviewed by Quinn and Myers 2004; Quinn 2005).”

“Throughout their anadromous life cycle, Pacific salmon Oncorhynchus spp. undergo significant migrations between freshwater and marine environments (Quinn and Myers 2004), and individuals also move within habitats (Quinn 2005).”

“Fry emerge the following spring (Burgner 1991) and typically inhabit the littoral zone before moving offshore to feed on zooplankton for the rest of their freshwater residence (Quinn 2005).”

“In most of the cases, individuals will return to the same beach or stream reach to spawn, but especially in years when sockeye salmon abundance is large, discrete spawning sites may begin to overlap as individuals are forced to nest in sub-optimal habitats between spawning sites (Quinn, 2005 ).”

“First, natal homing behaviour exhibited by Coho and other salmonids (Hendry et al., 2004; Quinn, 2018) is likely to maintain adaptive differences among populations.”

“Notably, this analysis allowed differentiation between the proportion of adult and juvenile Salmoniformes consumed.”

“In general, migration against water flow and gravitational force to upstream rivers from marine habitat is energetically costly (Quinn, 2005; Skov et al., 2008; Hulthen et al., 2014).”

“Pink salmon have the least variable life- history characteristics of all Pacific salmon, with a fixed 2- year life cycle and well- documented odd or even year dominance for a particular area (Quinn, 2005).”

“) and forage fish as they grow, rest, and migrate between spawning and rearing areas (Healey 1982; Simenstad 1982; Thorpe 1994; Quinn 2005).”

“Somatic growth, however, can be important for males competing for access to females during reproduction (Quinn, 2005).”

“Species of the genus Oncorhynchus within the family Salmonidae exhibit a diversity of life-history patterns among species as well as myriad of population-specific variants (Groot & Margolis, 1991; Quinn, 2005).”

“This phenomenon also makes it possible for hatchery-reared individuals released as juveniles to return to the release site as adults, even though their homing abilities are less prominent than for wild fish (Jokikokko, 2002; Quinn, 2005).”

“During this homeward migration, salmonids move 60 km per day in the near surface waters [Quinn, 2004] and have UV polarization sensitivity in their ventral retina [Beaudet et al.”

“Populations of steelhead consist of individuals that spawn at similar times and are genetically similar at neutral genetic markers, but adult individuals within a population may display significant variation in when they enter freshwater or arrive at spawning grounds (Quinn, 2018).”

“Pink salmon rely minimally on freshwater habitats compared to other salmonids (Quinn 2005), which may serve them especially well in the future given the potential impacts of climate change on freshwater ecosystems (Ward et al. 2015).”

“Direct genetic habitat choice: although a few studies suggested a possible genetic component to large-scale (different stream reaches) habitat choice (Quinn 2018), no study has even suggested that such a genetic basis could apply to fine-scale variation in nest site choice within salmon populations.”

“understanding the reasons for high mortality and thus improved resource management lies in being able to identify those factors that control the development of the incubating embryo (Quinn, 2005).”

“…et al. 2004, Moore et al. 2004, Verspoor et al. 2010, Winemiller et al. 2010), substrate complexity (Wolman 1954, Robson 1996, Biggs et al. 1999, Quinn 2005, Holtgrieve et al. 2010), grazer size and density (Rosemond et al. 1993, Robson 1996, Moore et al. 2004, Moore and Schindler 2008),…”

“Within the salmonids, coho salmon (Oncorhynchus kisutch) provides a simple study subject for studies on the effect of selection because it is strictly anadromous, and has shorter generation time and simpler age structure compared to most other salmonids; this species typically returns from the ocean at three years of…”

“In general, they grow slowly, as indicated by their smaller size at age when leaving freshwater compared with coho salmon, O. kisutch, a stream-rearing species, and smaller size for their age at sea than other Pacific salmon (Quinn 2005).”

“Early maturation in each studied population has a sex bias towards males as observed in other studies of salmonid species, such as Atlantic salmon, brown trout and Chinook salmon (Oncorhynchus tshawytscha) (Jonsson, 1985; Jonsson & Jonsson, 1993; Hendry et al., 2004; Quinn, 2005).”

“Population traits may vary according to latitude (e.g. size [Quinn, 2018]), migration difficulty (e.g. aerobic scope [Eliason et al., 2011]), migratory phenotype (Zillig et al., 2023) or river entry timing or migration distance (e.g. percentage of body fat [Crossin et al., 2004; Quinn, 2018]).”

“Salmonids from genera Salmo, Oncorhynchus and Salvelinus are among the most 78 famous and economically important migratory fishes (Quinn 2005; Harris and Milner 2007).”

“…and ocean arrival timing are often heritable and highly genetically correlated (Carlson and Seamons 2008), and Pacific salmon display subpopulation divergence in outmigration timing at both large (e.g., across latitudinal clines) and small (e.g., within a reach) spatial scales (Quinn 2005).”

“Coho are one of several ecologically important species of Pacific salmon that become exposed during residence or migration to environmental pollutants which have been linked to their population decline in the western United States [28,41].”

“…we perceive the operation of LA in salmon and other diadromous fishes, particularly given that the opportunity for divergent natural selection is often assumed (e.g. Quinn 2005; Garcia de Leaniz et al. 2007) to be larger during freshwater life history phases than during marine life history phases.”

“commence anadromy and their use of marine waters (Randall et al. 1987; Jonsson and Jonsson 1993, 2011; Quinn and Myers 2004; Quinn 2005; Pavlov and Savvaitova 2008).”

“04) (Quinn 2005).”

“While Chinook Salmon rarely occur as natural resident freshwater populations (Quinn, 2018 ), populations of O. mykiss may be primarily resident due to environmental conditions (e.g., Narum, Zendt, et al., 2008 ), or have been excluded from anadromy by anthropogenic barriers.”

“One component of the observed variability is the natural annual variability of fish populations (Quinn 2011).”

“They can become quickly established, extending their distribution at their native (Hendry, Castric, Kinnison, & Quinn, 2004; Quinn, 2005) and non-native ranges (Quinn et al., 2001).”

“…salmon are thought to use river plumes as transitional habitats for osmoregulation, feeding, and 579 Page 26 of 65 https://mc06.manuscriptcentral.com/cjfas-pubs Canadian Journal of Fisheries and Aquatic Sciences Draft Running page head: Predator-prey interactions river plume 27 refuge (Quinn 2005).”

“Anadromous Pacific salmonids (Oncorhynchus spp.) typically exhibit high fidelity to their natal tributaries (philopatry), despite the large distances that they traverse throughout their lifetime (Quinn, 2005; Keefer and Caudill, 2014).”

“This variation is typically attributed to differences in the rate of larval development between warm and cold streams (Quinn, 2005).”

“Additionally, recreational fishing often has strong cultural significance, such as in the tribal Pacific lamprey fishery [10] and Pacific salmon fishery [11].”

“In addition, Atlantic Salmon may be an ecological equivalent to Rainbow Trout, which are sympatric with Chinook Salmon and Coho Salmon in their native environment (Quinn 2005).”

“Semelparous Pacific salmon accumulate up to 99% of their body mass at sea before returning to freshwater systems where they spawn and die, often in high densities, delivering marine-derived nutrients to these typically nutrient-limited systems through their eggs, excretions and decomposing carcasses [10, 11, 12].”

“Consistent with most sockeye salmon populations (Quinn 2005), juveniles migrate quickly to the rearing lakes after emerging in rivers of the Chignik system.”

“Spatial maps could be constituted by a series of 330 submaps obtained through different sensory systems (Sovrano, Bisazza, & Vallortigara, 331 2003; Quinn, 2005).”

“On the west coast of the United States, formerly bundant salmonid species have experienced dramatic declines in opulation during the past several decades leading to many salmon opulations being listed under the Endangered Species Act for proection (Quinn, 2005).”

“ing is also thought to be related to infection and disease in many cases (Quinn 2005; Bradford et al. 2010).”

“628 Low genetic divergence at neutral loci among populations is often the result of high levels of contemporary gene flow.”

“In conclusion, the present study describes the cloning, expression, and function of the major olfactory GSTs in coho salmon, one of seven Pacific salmon species whose populations have declined due to urbanization [60].”

“This species matures and returns to the freshwater environment between ages 3 and 6, and fry emerge and migrate to the ocean in spring during ice-out (Quinn 2005).”

“Marine fish are no exception, as salmon return to their natal rivers to spawn (Dittman and Quinn 1996; Quinn 2005) and Atlantic cod return to their spawning grounds in the sea (Green and Wroblewski 2000; Rawson and Rose 2000; Robichaud and Rose 2001).”

“We wanted to compare isotope signatures corresponding to the time steelhead spent at sea, when they achieve more than 98% of their mature adult mass (Quinn 2005).”

“In this study, we focus on juvenile Chinook salmon (Oncorhynchus tshawytscha), which use estuaries for rearing and migration (Quinn 2005), and have been suggested to be the most estuarine dependent of the salmon species (Oncorhynchus sp.) (Healey 1982).”

“They are semelparous and die after spawning (Quinn, 2005).”

“However, this was before the release of that year ’ s juvenile hatchery salmon and the typical out-migration of most juvenile wild salmon (Weitkamp and Sturdevant 2008; Quinn 2018; NSRAA 2020).”

“For example, juvenile Chinook salmon rear in streams for up to two years before outmigrating (Quinn 2018).”

“This is best exemplified by species with complex life cycles, such as the steelhead trout (Oncorhynchus mykiss), who in the wild typically migrate between freshwater and saltwater environments several times throughout their lives [48].”