Juvenile production variation in salmonids: population dynamics, habitat, and the role of spatial relationships

Kocik, John F.; Ferreri, C. Paola

doi:10.1139/d98-015

Cited by 62 publications

(43 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Despite the frequency of DD juvenile mortality for stream salmonids, their natural reproductive and emergence behavior results in fry distributed in high-density patches in space and time (Brannas 1995;Kocik and Ferreri 1998), apparently exacerbating the eVects of density dependence (Armstrong 2005;Einum and Nislow 2005). Some restoration and management strategies for salmon seek to overcome this strong spatial density dependence by evenly distributing fry at low density (e.g.…”

Section: Importance For Populationsmentioning

confidence: 98%

Predators reverse the direction of density dependence for juvenile salmon mortality

Ward¹,

Nislow²,

Folt³

2008

Oecologia

View full text Add to dashboard Cite

The effect of predators on prey populations depends on how predator-caused mortality changes with prey population density. Predators can enforce density-dependent prey mortality and contribute to population stability, but only if they have a positive numerical or behavioral response to increased prey density. Otherwise, predator saturation can result in inversely density-dependent mortality, destabilizing prey populations and increasing extinction risk. Juvenile salmon and trout provide some of the clearest empirical examples of density-dependent mortality in animal populations. However, although juvenile salmon are very vulnerable to predators, the demographic effects of predators on juvenile salmon are unknown. We tested the interactive effects of predators and population density on the mortality of juvenile Atlantic salmon (Salmo salar) using controlled releases of salmon in natural streams. We introduced newly hatched juvenile salmon at three population density treatments in six study streams, half of which contained slimy sculpin (Cottus cognatus), a common generalist predator (18 release sites in total, repeated over two summers). Sculpin reversed the direction of density dependence for juvenile salmon mortality. Salmon mortality was density dependent in streams with no sculpin, but inversely density dependent in streams where sculpin were abundant. Such predator-mediated inverse density dependence is especially problematic for prey populations suppressed by other factors, thereby presenting a fundamental challenge to persistence of rare populations and restoration of extirpated populations.

show abstract

Section: Importance For Populationsmentioning

confidence: 98%

Predators reverse the direction of density dependence for juvenile salmon mortality

Ward¹,

Nislow²,

Folt³

2008

Oecologia

View full text Add to dashboard Cite

show abstract

“…However, in one study (Armstrong et al 1998a) it was possible to determine that previous experience of the pool areas (Armstrong et al 1997) was a significant factor in using those patches as refuges. This result suggests that not only is juxtaposition of habitat patches important (Kocik & Ferreri 1998), but so are the familiar areas and cognitive abilities of the fish in responding appropriately to changes in space quality across discharges. Interestingly, large radio tagged free-ranging salmon parr in a large regulated river had large home ranges and avoided stranding during large changes in water height (Berland et al 2004).…”

Section: Responding To Change: Patch Switchingmentioning

confidence: 73%

Variation in Habitat Quality for Drift‐Feeding Atlantic Salmon and Brown Trout in Relation to Local Water Velocity and River Discharge

Armstrong

2010

Salmonid Fisheries

View full text Add to dashboard Cite

There is a requirement to determine the effect of water discharge on the qualities of rivers and streams for resident drift-feeding salmon and trout. Two main categories of predictive biological model have been widely considered to address this issue, both of which link to an underlying template of variation in structure of hydrology and physical topology across flows. The first approach, typified by physical habitat simulation modelling (PHabSim), ascribes values to each of the local habitat types as functions of the densities and frequency of occurrence of animals that occupy them. This approach has the advantage of being relatively easily applied but has been criticised on the basis that local fish density can be a poor indicator of patch quality and does not easily relate overall habitat quality to meaningful population parameters. The second approach ascribes values to the local habitat types in terms of the food intakes, net energy gains or fitness of animals that occupy them. This concept has found favour in being potentially more robust in structure than the PHabSim approach, but parameterisation of the models cannot be achieved by simple field observations. Here, the application of energy and fitness value models to salmon and trout is explored. Morphological differences between salmon and trout are related to patch quality in terms of energetics through linking optimal food intake models to energy budgets. Using these models, relationships are established between velocity niche width and population density and nutrient status of the stream. The trout velocity niche is narrower than that of salmon and skewed to lower velocities, particularly at low food availability. The importance of understanding community dynamics in predicting responses of fish to variations in discharge is demonstrated. Consideration is given to factors that further affect the values of patches and their availability to salmon and trout. These 1 Salmonid Fisheries: Freshwater Habitat Management Paul Kemp

show abstract

“…The Santa Cruz has no secondor third-order tributaries, where the highest abundance of juvenile salmonids is found in other rivers around the world (Murphy et al, 1989;Boughton et al, 2009). The main stem itself is largely homogeneous, without a clear division in subsections or reaches, as opposed to most of the rivers, where studies of salmonid habitat have been carried out (Heggenes, 1990;Kocik & Ferreri, 1998). Our model selection procedure led us to a simple and biologically meaningful model to explain juvenile trout relative abundance based on three predictor variables: wetted width, substrate size, and rkm.…”

Section: Discussionmentioning

confidence: 99%

Dams versus habitat: predicting the effects of dams on habitat supply and juvenile rainbow trout along the Santa Cruz River, Patagonia

et al. 2015

View full text Add to dashboard Cite

Because of their remote location and lack of supporting infrastructure, large glacial rivers of southern Patagonia have remained free of dams. But this is bound to change: two dams proposed for the Santa Cruz River would supply 16% of Argentina's hydropower and five dams planned for the Pascua and Baker Rivers could supply over 20% of Chile's hydropower. In this paper, we project the losses of habitat and juvenile Oncorhynchus mykiss, a recreationally important species, following the construction of the two dams in the Santa Cruz River. We applied a two-stage fitting approach, using generalized additive models and generalized lineal models (GLMs) sequentially to describe habitat-species relationships based on data collected through an intensive field survey of fish and environmental variables along 310 km of river. A simplified GLM trout model based on wetted width, substrate size, and river kilometer was selected which represents the observed geographic distribution very well and with the lowest predictive error. Based on this model, we estimated that habitat supporting 86% of current juvenile trout production will be lost to flooding by the dams. Our data generate a rare opportunity to perform a dam impact assessment by comparison with potential post-dam conditions.

show abstract

Juvenile production variation in salmonids: population dynamics, habitat, and the role of spatial relationships

Cited by 62 publications

References 34 publications

Predators reverse the direction of density dependence for juvenile salmon mortality

Predators reverse the direction of density dependence for juvenile salmon mortality

Variation in Habitat Quality for Drift‐Feeding Atlantic Salmon and Brown Trout in Relation to Local Water Velocity and River Discharge

Dams versus habitat: predicting the effects of dams on habitat supply and juvenile rainbow trout along the Santa Cruz River, Patagonia

Contact Info

Product

Resources

About