دانلود رایگان مقاله نرخ ته نشینی درونی پخش فضایی قرص خوراک ماهی

Abstract

Spatial and temporal feed distribution in sea cages are important factors for the farmer, fish and environment due to the strong relation to growth, feed loss, pollution and welfare. This study presents a set of experimentally derived diffusion parameters and settling rates obtained in still water from four sizes and three densities of extruded fish feed pellets commonly used in aquaculture. It was found that pellet size is positively correlated with increased diffusion and that pellet density plays a less important role. Both the size and density of pellets had a significant impact on the settling rate. Results are compared to values obtained during feed production as well as other relevant studies. The findings suggest that parameters related to hydrodynamic behaviour of groups of feed pellets may vary across different pellet types. The results may be applied to refine and parameterize pellet motion in sea cage feeding models, improving estimates of fish behaviour, growth and feed loss.

5. Conclusion

This study has examined the horizontal diffusion and settling rate based on experiments with four sizes and three densities of extruded salmon pellets under stationary water conditions. For horizontal diffusion only the pellet size had a significant impact on the radial distance from the centre of mass while both the size and density affected the settling rate. The results have been used to refine and parameterize a sea cage model (Alver et al., 2016) where pellet motion plays an essential role. These results allow for spatiotemporal pellet distribution and water flow induced motion to be more accurately modelled by hydrodynamics and equations of motion based on the presented experimentally derived parameters. These findings will expectedly yield improved model estimates of pellet motion within a sea cage, fish behaviour and feed loss.