Construction of a factorial phosphorus requirement model for salmonid fish across life stages

Description

Phosphorus (P) is a key component of fish culture waste because it is generally the most limiting nutrient for plant growth in fresh water. Excessive inputs of P to fresh waters can lead to increased algae growth and decreased oxygen concentrations. An effective approach to minimizing the environmental impacts from fish culture operations is to reduce P waste outputs. This can be effectively achieved through the use of feeds containing digestible P levels closely meeting, but not exceeding, the dietary requirements of the fish. Differences in feed composition, fish size, life stages, and feeding techniques have resulted in a wide variation in the estimates of P requirements and waste outputs of fish in the scientific literature. Few attempts have been made so far to integrate the available information in a rational manner. This project includes two parts. The first part involves the construction of a model, based on data found in published scientific studies that mathematically describes P utilization by trout and salmon throughout their life cycle in fresh water. This model is composed of various sub-models used to predict 1) digestibility of P in fish feeds, 2) the concentration of P in the body of fish, and 3) P waste outputs by fish culture operations. The second part of the project will involve a series of feeding trials with rainbow trout to improve or validate the model. A simple model interface (software) will be developed and nutritional strategies to minimize P waste output will then be explored. As of December 2003, construction of the P utilization model is completed and validation of the model is underway. The model and its software will be a useful tool for predicting P waste outputs from fish culture operations. It will also be useful to explore nutritional strategies to reduce and minimize P waste outputs and environmental impact of freshwater aquaculture operations.

Program Name

Aquaculture Collaborative Research and Development Program (ACRDP)

Year(s)

2002 - 2005

Ecoregion(s)

National

Principal Investigator(s)

Art Niimi
Email: NiimiA@dfo-mpo.gc.ca