Size-Biased Survival in Steelhead Trout (<i>Oncorhynchus mykiss</i>): Back-Calculated Lengths from Adults' Scales Compared to Migrating Smolts at the Keogh River, British Columbia

Ward, Bruce R.; Slaney, P. A.; Facchin, A. R.; Land, R. W.

doi:10.1139/f89-233

Cited by 125 publications

(114 citation statements)

References 2 publications

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“…High rates of mortality on smaller, slower-growing individuals following ocean entry has been previously documented in other species and stocks of juvenile salmon using mark-recapture techniques (Parker 1968, Bilton et al 1982, Bax 1983, Duffy & Beauchamp 2011, back-calculated size and growth estimates with scales (Healey 1982, Ward et al 1989, Holtby et al 1990, Cross et al 2008, and otoliths (Neilson & Geen 1986, Good et al 2001). Despite previous studies of this kind on other salmonid species and stocks, no similar work has been done for California's Central Valley Chinook salmon -the overwhelming contributor to the commercial and recreational salmon fisheries off California.…”

Section: Introductionmentioning

confidence: 77%

Size, growth, and origin-dependent mortality of juvenile Chinook salmon Oncorhynchus tshawytscha during early ocean residence

Woodson¹,

Wells²,

Weber³

et al. 2013

Mar. Ecol. Prog. Ser.

103

135

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Selective mortality during early life history stages can have significant populationlevel consequences, yet critical periods when selective mortality occurs, the strength of selection, and under what environmental conditions can be difficult to identify. Here, we used otolith microstructure and chemistry to examine the factors potentially linked to selective mortality of juvenile fall-run Chinook salmon Oncorhynchus tshawytscha from California's Central Valley during early ocean residence. Back-calculated size and growth rates of the population were compared across 3 sample periods: as juveniles exited the San Francisco Bay estuary (estuary-exit), after their first month at sea (summer-ocean) and 5 mo after ocean entry (fall-ocean). We compared mortality dynamics during years of exceptional recruitment (addition of individuals to harvestable population; 2000 and 2001) to a year of poor recruitment (2005). Otoliths from 2005 were also analyzed for sulfur isotopes to discern hatchery from naturally spawned stock. Significant size and growth-rate selective mortality were detected during the first month at sea in the low recruitment year of 2005, but not in 2000 and 2001. Individuals that were larger and growing faster during freshwater and estuarine rearing were more likely to survive to summer and fall in the low recruitment year. There was a slight, but insignificant, increase in the proportion of hatchery to naturally spawned individuals from estuary-exit to fall-ocean, suggesting that fish from neither origin were overwhelmingly favored. Our results suggest that Central Valley Chinook salmon can be subject to significant size and growth-rate selective mortality resulting in low adult abundance, and this mortality appears independent of origin.

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Section: Introductionmentioning

confidence: 77%

Size, growth, and origin-dependent mortality of juvenile Chinook salmon Oncorhynchus tshawytscha during early ocean residence

Woodson¹,

Wells²,

Weber³

et al. 2013

Mar. Ecol. Prog. Ser.

103

135

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“…However, analysis of Skagit River steelhead scales indicated size selective smolt-to-adult survival (Thompson & Beauchamp 2014), and smolt size was positively correlated with adult survival of both Columbia River (Evans et al 2014) and Keogh River steelhead (Ward et al 1989). Size selective mortality has been observed in other species of salmon as well; adults that had been large as smolts were over-represented, relative to the abundance of that size class, among the smolts (Healey 1982, Holtby et al 1990, Henderson & Cass 1991.…”

Section: Discussionmentioning

confidence: 99%

“…The majority of lifetime mortality typically takes place during the freshwater stages, but the mortality at sea is substantial, variable among years, and occurs later in the life cycle, so there are fewer opportunities for compensation compared to mortality that occurs during earlier, freshwater stages (Bradford 1995, Quinn 2005. Most studies of marine mortality have investigated (1) environmental factors related to 'smolt-toadult' survival (Mantua et al 1997, Coronado & Hilborn 1998, (2) patterns of survival or recruitment over various spatial areas (Pyper et al 2005, Sharma et al 2013, (3) scale growth patterns to assess sizeselective mortality (Ward et al 1989, Holtby et al 1990, Henderson & Cass 1991, Moss et al 2005, or (4) the effects of specific predators on populations of interest (Beamish et al 1992, Willette et al 2001). …”

Section: Introductionmentioning

confidence: 99%

Multi-population analysis of Puget Sound steelhead survival and migration behavior

Moore¹,

Berejikian²,

Goetz³

et al. 2015

Mar. Ecol. Prog. Ser.

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Until recently, research on mortality of anadromous fishes in the marine environment was largely limited to estimates of total mortality and association with group characteristics or the environment. Advances in sonic transmitter technology now allow estimates of survival in discrete marine habitats, yielding important information on species of conservation concern. Previous telemetry studies of steelhead Oncorhynchus mykiss smolts in Puget Sound, Washington, USA indicated that approx. 80% of fish entering marine waters did not survive to the Pacific Ocean. The present study re-examined data from previous research and incorporated data from additional Puget Sound populations (n = 7 wild and 6 hatchery populations) tagged during the same period (2006−2009) for a comprehensive analysis of steelhead early marine survival. We used mark-recapture models to examine the effects of several factors on smolt survival and to identify areas of Puget Sound where mortality rates were highest. Wild smolts had higher survival probabilities in general than hatchery smolts, with exceptions, and wild smolts released in early April and late May had a higher probability of survival than those released in early and mid-May. Steelhead smolts suffered greater instantaneous mortality rates in the central region of Puget Sound and from the north end of Hood Canal through Admiralty Inlet than in other monitored migration segments. Early marine survival rates were low (16.0 and 11.4% for wild and hatchery populations, respectively) and consistent among wild populations, indicating a common rather than watershed-specific mortality source. With segment-specific survival information we can begin to identify locations associated with high rates of mortality, and identify the mechanisms responsible.

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“…Because growth is largely indeterminate in fishes, density-dependent changes in individual growth rates can affect other fitness components such as survival and fecundity at subsequent life stages (Werner and Gilliam 1984, Morita and Takashima 1998, Einum and Fleming 1999. Although anadromous salmonids depend on more than juvenile rearing habitat to complete a generation, rapid growth and large body size has been shown to confer fitness advantages through increased survival (Ward and Slaney 1988, Ward et al 1989, Kahler et al 2001. Growth during juvenile stages can therefore have important ramifications for population dynamics (Sogard 1997, Rose et al 2001, particularly in small populations inhabiting or navigating highly altered habitats to complete their life cycle.…”

Section: Discussionmentioning

confidence: 99%

Density dependence and its impact on individual growth rates in an age‐structured stream salmonid population

Myrvold

Kennedy

2015

Ecosphere

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Citation: Myrvold, K. M., and B. P. Kennedy. 2015. Density dependence and its impact on individual growth rates in an age-structured stream salmonid population. Ecosphere 6(12):281. http://dx.doi.org/10.1890/ES15-00390.1Abstract. In organisms with flexible and indeterminate growth, demographic density dependence can affect both individual fitness and population dynamics. Recent work in stream salmonids suggests that individual growth rates can be depressed even at low population densities, which warrants examination of populations previously assumed to be below carrying capacity. We investigated the effects of population density on individual growth rates in a threatened population of steelhead (Oncorhynchus mykiss) in a tributary to the Clearwater River in Idaho, USA. We followed a mark-recapture design where we visited 16 study sites on average five times per year from 2010 to 2012. The 95% confidence interval for average growth rates (% change in body mass per day) for subyearlings were [0.82, 1.0]) and [0.16, 0.30] for yearling steelhead. Variance decomposition showed that the variation in growth rates could be attributed equally to individual-and visit-level factors in subyearlings, whereas almost two-thirds of the variance in yearling growth rates could be attributed to individual-level factors. Growth rates in the subyearling age class were negatively related to the densities of yearling steelhead, but not vice versa. Yearling growth rates showed no evidence of density dependence. Finally, density in interaction with water temperature did not affect growth rates of either age class. Our results demonstrate that density dependence can pose constraints on individual growth rates at low population densities (,1 fish m À2 ) in stream salmonids, and underscore the importance of considering age classes separately when studying density dependence in age-structured populations.

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Size-Biased Survival in Steelhead Trout (Oncorhynchus mykiss): Back-Calculated Lengths from Adults' Scales Compared to Migrating Smolts at the Keogh River, British Columbia

Cited by 125 publications

References 2 publications

Size, growth, and origin-dependent mortality of juvenile Chinook salmon Oncorhynchus tshawytscha during early ocean residence

Size, growth, and origin-dependent mortality of juvenile Chinook salmon Oncorhynchus tshawytscha during early ocean residence

Multi-population analysis of Puget Sound steelhead survival and migration behavior

Density dependence and its impact on individual growth rates in an age‐structured stream salmonid population

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