Salmonid Fisheries (Freshwater Habitat Management) || Variation in Habitat Quality for Drift-Feeding Atlantic Salmon and Brown Trout in Relation to Local Water Velocity and River Discharge
✍ Scribed by Kemp, Paul
- Publisher
- Wiley-Blackwell
- Year
- 2010
- Weight
- 450 KB
- Edition
- 1
- Category
- Article
- ISBN
- 1405183969
No coin nor oath required. For personal study only.
✦ Synopsis
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