Development of natural growth regimes for hatchery-reared steelhead to reduce residualism, fitness loss, and negative ecological interactions

Berejikian, Barry A.; Larsen, Donald A.; Swanson, Penny; Moore, Megan E.; Tatara, Christopher P.; Gale, William L.; Pasley, Chris R.; Beckman, Brian R.

doi:10.1007/s10641-011-9788-0

Cited by 33 publications

(36 citation statements)

References 58 publications

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“…Fish that were moving downstream were also captured in the lower reaches of the rivers in rotary screw traps during April and May and were categorized as smolts, and thus were adopting an anadromous life history, if they were greater than 125 mm. This threshold size for smoltification is consistent with other populations [33]. At this size fish show silvering and loss of parr marks, development of dark margins on the fins, loosening of the scales and body elongation [34].…”

Section: Methodssupporting

confidence: 86%

Gene Flow between Sympatric Life History Forms of Oncorhynchus mykiss Located above and below Migratory Barriers

2013

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Oncorhynchus mykiss have a diverse array of life history types, and understanding the relationship among types is important for management of the species. Patterns of gene flow between sympatric freshwater resident O. mykiss, commonly known as rainbow trout, and anadromous O. mykiss, commonly known as steelhead, populations are complex and poorly understood. In this study, we attempt to determine the occurrence and pathways of gene flow and the degree of genetic similarity between sympatric resident and anadromous O. mykiss in three river systems, and investigate whether resident O. mykiss are producing anadromous offspring in these rivers, two of which have complete barriers to upstream migration. We found that the population structure of the O. mykiss in these rivers appears to be influenced more by the presence of a barrier to upstream migration than by life history type. The sex ratio of resident O. mykiss located above a barrier, and smolts captured in screw traps was significantly skewed in favor of females, whereas the reverse was true below the barriers, suggesting that male resident O. mykiss readily migrate downstream over the barrier, and that precocious male maturation may be occurring in the anadromous populations. Through paternity analyses, we also provide direct confirmation that resident O. mykiss can produce offspring that become anadromous. Most (89%) of the resident O. mykiss that produced anadromous offspring were males. Our results add to the growing body of evidence that shows that gene flow does readily occur between sympatric resident and anadromous O. mykiss life history types, and indicates that resident O. mykiss populations may be a potential repository of genes for the anadromous life history type.

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Section: Methodssupporting

confidence: 86%

Gene Flow between Sympatric Life History Forms of Oncorhynchus mykiss Located above and below Migratory Barriers

2013

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“…In this section, Beaver Creek is a third-order stream at low elevation (463-548 m) and relatively small in wetted width (4.6 ± 0.2 m [mean ± SE]) and discharge at base flow (0.05 m 3 /s; Martens and Connolly 2010). The Steelhead population in the Methow River basin is supported by hatchery releases of smolts (Berejikian et al 2012), but in Beaver Creek the population is largely from natural spawning O. mykiss. Although O. mykiss is the dominant fish species, other fish present in Beaver Creek include Chinook Salmon, Brook Trout Salvelinus fontinalis, and Shorthead Sculpin Cottus confusus (Martens and Connolly 2010).…”

Section: Methodsmentioning

confidence: 99%

Potential Effects of Changes in Temperature and Food Resources on Life History Trajectories of Juvenile Oncorhynchus mykiss

et al. 2012

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Increasing temperatures and changes in food resources owing to climate change may alter the growth and migratory behavior of organisms. This is particularly important for salmonid species like Oncorhynchus mykiss, where some individuals remain in freshwater to mature (nonanadromous Rainbow Trout) and others migrate to sea (anadromous Steelhead). Whether one strategy is adopted over the other may depend on the individual's growth and size. In this study, we explored (1) how water temperature in Beaver Creek, a tributary to the Methow River, Washington, may increase under four climate scenarios, (2) how these thermal changes may alter the life history trajectory followed by O. mykiss (i.e., when and if to smolt), and (3) how changes in food quality or quantity might interact with increasing temperatures. We combined bioenergetic and state‐dependent life history models parameterized for O. mykiss in Beaver Creek to mimic baseline life history trajectories. Based on our simulations, when mean water temperature was increased by 0.6°C there was a reduction in life history diversity and a 57% increase in the number of individuals becoming smolts. When mean temperature was increased by 2.7°C, it resulted in 87% fewer smolts than in the baseline and fewer life history trajectories expressed. A reduction in food resources led to slower growth, more life history trajectories, and a greater proportion of smolts. In contrast, when food resources were increased, fish grew faster, which reduced the proportion of smolts and life history diversity. Our modeling suggests that warmer water temperatures associated with climate change could decrease the life history diversity of O. mykiss in the central portion of their range and thereby reduce resiliency to other disturbances. In addition, changes in food resources could mediate or exacerbate the effect of water temperature on the life history trajectories of O. mykiss.

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“…Growth patterns of hatchery and naturally reared steelhead in freshwater profoundly differ (Berejikian et al. ). Wild steelhead typically spend two or more years in freshwater before undergoing the physiological changes to allow for life in seawater (smolting) and migrating to the ocean (Randall et al.…”

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confidence: 99%

“…Anadromous salmonids that do not undergo smoltification and migrate during the primary migration period are referred to as “residuals” and can occur in both S1 and S2 steelhead programs (Berejikian et al. ). Reduced age at smoltification in S1 programs has been associated with selection for higher growth rates in culture (Berejikian et al.…”

mentioning

confidence: 99%

“…Although both S1 and S2 programs produce residuals with the parr and precocious mature male phenotypes, the parr phenotype tends to predominate in S1 programs, while the mature male phenotype is more common in S2 programs (Berejikian et al. ). Residual steelhead may represent an important component of the natural life history portfolio for steelhead (Moore et al.…”

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confidence: 99%

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Age at Release, Size, and Maturation Status Influence Residualism in Hatchery Steelhead

Tatara

Larsen

Cooper

et al. 2019

N American J Fish Manag

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Steelhead Oncorhynchus mykiss that fail to emigrate seaward after release from hatcheries, commonly referred to as “residuals,” can have negative impacts on natural populations ranging from competition and predation to interbreeding with returning anadromous adults. We investigated how age at release, size, and maturation status influenced the rate of residual production in hatchery summer‐run steelhead released from the Winthrop National Fish Hatchery (Methow River, Washington) between 2010 and 2015. Migration data from 21,598 individuals implanted with PIT tags identified 1,783 residual steelhead expressing two distinct phenotypes: immature male and female parr; and precociously mature males. We found that age at release significantly affected the predominant residual phenotype. Age‐1 steelhead residuals (S1 rearing strategy) were dominated by smaller parr of both sexes (fish < 146 mm FL), while age‐2 residuals (S2 rearing strategy) were dominated by mature males, although both phenotypes were present in both S1 and S2 residual groups. Collections of residual steelhead in the Methow River indicated that parr phenotype residuals grew as well as natural‐origin juvenile O. mykiss, suggesting potential competition for food resources and habitat. Detections of PIT tags within the Methow River basin indicated that precocious male residuals may overlap both spatially and temporally with previously documented spawning anadromous adults, posing a potential genetic management risk. Both residual phenotypes had poor overwinter survival, and only 1 of the 1,783 residual fish eventually returned to the Methow River as an anadromous adult. We conclude that the ecological and genetic consequences of residual steelhead far outweigh their potential contribution to anadromous production, and measures should be taken to reduce their production by changing hatchery rearing practices.

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Development of natural growth regimes for hatchery-reared steelhead to reduce residualism, fitness loss, and negative ecological interactions

Cited by 33 publications

References 58 publications

Gene Flow between Sympatric Life History Forms of Oncorhynchus mykiss Located above and below Migratory Barriers

Gene Flow between Sympatric Life History Forms of Oncorhynchus mykiss Located above and below Migratory Barriers

Potential Effects of Changes in Temperature and Food Resources on Life History Trajectories of Juvenile Oncorhynchus mykiss

Age at Release, Size, and Maturation Status Influence Residualism in Hatchery Steelhead

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