Patterns of density‐dependent growth in juvenile stream‐dwelling salmonids

Grant, James W. A.; Imre, István

doi:10.1111/j.0022-1112.2005.00916.x

Cited by 152 publications

(165 citation statements)

References 31 publications

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“…First of all, local fish density had negative effects on juvenile coho growth rate, confirming the importance of densitydependent growth in stream-dwelling salmonid populations (Jenkins et al 1999, Grant andImre 2005). Secondly, the negative growth effect we observed occurred at relatively low fish densities (;0.02-0.9 fish/m 2 ), a pattern observed in other studies (see Jenkins et al 1999).…”

Section: Field Studysupporting

confidence: 89%

“…Possibly exacerbating this scenario is the release of hatchery fish, which is commonly used to augment salmon populations (e.g., Einum et al 2009). Artificial supplementation of fish populations or other species has clear benefits when they face immediate risk of extinction (Young 1999), but in resource-limited systems it may have negative demographic consequences for wild populations because territorial species, such as stream-dwelling salmonids, are strongly affected by density-dependent interactions (our study, Jenkins et al 1999, Grant and Imre 2005, Buhle et al 2009, Einum et al 2009). …”

Section: Synthesis and Implicationsmentioning

confidence: 97%

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Linking resource availability and habitat structure to stream organisms: an experimental and observational assessment

et al. 2014

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An experiment and a mark‐recapture field study of juvenile coho salmon (Oncorhynchus kisutch) were conducted to identify controls of key energy flow chains in river food webs. In the small‐scale experiment, we investigated the individual and interactive effects of physical habitat structure (PHS) as small wood and resource availability (tissue of adult Chinook salmon, O. tshawytscha) on nutrients, algae, invertebrates, and fish predators including juvenile coho. In the field, we quantified the effects of natural variation in prey availability (invertebrate drift biomass), PHS (wood), and local fish density on summer growth of juvenile coho across multiple stream reaches. Adding salmon tissue to experimental channels resulted in strong bottom‐up effects on select invertebrates including increased population biomass of chironomids and baetids, the numerically dominant invertebrates, and faster growth of juvenile coho. We link the enhanced growth of coho to chironomid productivity: for instance, adult chironomid flux was 4.3× higher and coho consumption of these animals 3× higher in salmon‐subsidized channels. PHS in experimental channels was associated with reduced algal biomass, potentially in response to increased invertebrate consumption, and invertebrate flux or export. The field study revealed coho growth was negatively related to PHS and total fish density and positively related to Diptera drift biomass; however, the effects of fish density and drift biomass on coho growth were relatively weak. The field study also indicated that prey resource availability and coho growth were associated with differences in canopy cover, with prey biomass and coho growth 2–4× higher in reaches receiving more sunlight. As in the experiment, coho in natural stream reaches predominantly fed on adult chironomids and other Diptera, indicating that these taxa and life‐stages are a key link between the benthic food web and mobile vertebrate predators. Our study showed that bottom‐up processes initiated by salmon subsidies and possibly light flux determined key trophic interactions in the Cedar River food web. Moreover, we speculate that PHS may modify some of these interactions indirectly through its effects on the movement of organisms through the environment.

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Section: Field Studysupporting

confidence: 89%

Section: Synthesis and Implicationsmentioning

confidence: 97%

Linking resource availability and habitat structure to stream organisms: an experimental and observational assessment

et al. 2014

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“…Although we did survey resident fish densities in three years and observed little among year variation (Appendix A), these years happened to coincide with lower than average salmon densities in both streams. Thus, it is possible that densities of resident fish were higher in Lynx and Hidden creeks when salmon densities were higher leading to density-dependent growth, a phenomenon widely reported in stream-dwelling salmonid populations (Bohlin et al 2002, Grant andImre 2005). Unfortunately, due to high variation in growth rates among individual fish captured at the same salmon density and the limited number of data from years around the inflection point, we were unable to predict the exact density where superimposition occurred with high confidence (Appendix D: Table D1).…”

Section: Discussionmentioning

confidence: 95%

Foraging and growth responses of stream‐dwelling fishes to inter‐annual variation in a pulsed resource subsidy

Bentley¹,

Schindler²,

Armstrong³

et al. 2012

Ecosphere

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Abstract. Pulsed resource subsidies generate ephemeral fluxes of nutrients and energy among ecosystems. The effects of pulsed subsidies should depend on the magnitude of the pulse, the in situ productivity of the recipient system, and the ability of consumers to capitalize on the resources, yet empirical data on these relationships are limited. We assessed the ecological consequences of variation in resource pulse magnitude, as represented by anadromous salmon returns, for the foraging and growth responses of two species of stream-dwelling salmonids in two streams that vary in productivity in southwestern Alaska. Over 11 years and across a greater than 10-fold variation in sockeye salmon (Oncorhynchus nerka) density, both rainbow trout (O. mykiss) and Arctic grayling (Thymallus arcticus) exhibited a relatively similar, but mechanistically different, non-linear saturating growth response to increasing salmon density. This growth response was driven by both an increase in consumption of salmon eggs and also a decrease in dietary overlap between the two species. However, the relative change in growth from low to high salmon densities was different between streams and depended on in situ stream productivity. In low salmon density years the growth of resident consumers fell 46-68% relative to high years in the low productivity stream, but only by 26-34% in the high productivity stream. Our study provides strong evidence that understanding of both the foraging ecology of consumers and the in situ productivity of recipient ecosystems, which together regulate the ecological consequences of variation in resource subsidies, is required for successful implementation of ecosystem-based management in systems dependent on pulsed resource subsidies.

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“…The first is through direct effects on growth and survival, mediated through competition for food and space (Grant and Imre 2005;Keeley 2001). Theoretically, increased competition for food resources decreases growth and size, in turn leading to a higher number of ocean migrants within a population (Hendry et al 2004;Jonsson and Jonsson 1993 ; Fig.…”

Section: Density Dependencementioning

confidence: 99%

Anadromy and residency in steelhead and rainbow trout (Oncorhynchus mykiss): a review of the processes and patterns

Kendall

McMillan

Sloat

et al. 2015

Can. J. Fish. Aquat. Sci.

217

224

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Abstract:Oncorhynchus mykiss form partially migratory populations with anadromous fish that undergo marine migrations and residents that complete their life cycle in fresh water. Many populations' anadromous components are threatened or endangered, prompting interest in understanding ecological and evolutionary processes underlying anadromy and residency. In this paper, we synthesize information to better understand genetic and environmental influences on O. mykiss life histories, identify critical knowledge gaps, and suggest next steps. Anadromy and residency appear to reflect interactions among genetics, individual condition, and environmental influences. First, an increasing body of literature suggests that anadromous and resident individuals differ in the expression of genes related to growth, smoltification, and metabolism. Second, the literature supports the conditional strategy theory, where individuals adopt a life history pattern based on their conditional status relative to genetic thresholds along with ultimate effects of size and age at maturation and iteroparity. However, except for a generally positive association between residency and high lipid content plus a large attainable size in fresh water, the effects of body size and growth are inconsistent. Thus, individuals can exhibit plasticity in variable environments. Finally, patterns in anadromy and residency among and within populations suggested a wide range of possible environmental influences at different life stages, from freshwater temperature to marine survival. Although we document a number of interesting correlations, direct tests of mechanisms are scarce and little data exist on the extent of residency and anadromy. Consequently, we identified as many data gaps as conclusions, leaving ample room for future research.Résumé : Les truites arc-en-ciel (Oncorhynchus mykiss) forment des populations partiellement migratrices incluant des individus anadromes qui effectuent des migrations marines et des individus résidents dont le cycle biologique se déroule entièrement en eau douce. Les éléments anadromes de nombreuses populations sont menacés ou en voie de disparition, ce qui suscite un intérêt envers la compréhension des processus écologiques et évolutionnaires qui sous-tendent l'anadromie et la résidence. Nous présentons une synthèse de l'information disponible dans le but de mieux comprendre les influences génétiques et environnementales sur les cycles biologiques d'O. mykiss, de cerner les lacunes critiques en matière de connaissances et de proposer des avenues de recherche future. L'anadromie et la résidence semblent témoigner d'interactions entre la génétique, l'état des individus et des influences environnementales. D'abord, de plus en plus d'études donnent à penser que les individus anadromes et résidents diffèrent sur le plan de l'expression des gènes associés à la croissance, à la smoltification et au métabolisme. Deuxièmement, la documentation appuie la théorie de la stratégie conditionnelle selon laquelle les individus adoptent un m...

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Patterns of density‐dependent growth in juvenile stream‐dwelling salmonids

Cited by 152 publications

References 31 publications

Linking resource availability and habitat structure to stream organisms: an experimental and observational assessment

Linking resource availability and habitat structure to stream organisms: an experimental and observational assessment

Foraging and growth responses of stream‐dwelling fishes to inter‐annual variation in a pulsed resource subsidy

Anadromy and residency in steelhead and rainbow trout (Oncorhynchus mykiss): a review of the processes and patterns

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