Objectives:

Objective1 Review the current knowledge on the transport pathway of phosphorus in feed and faecal material from freshwater production in Scotland, and in particular, determine whether existing information is representative of modern feeds in use and feeds new to market

Objective 2 Review current use of the OECD equation and similar models in the context of freshwater lochs in Scotland

Objective3 Review the existing monitoring survey data sets of freshwater lochs containing aquaculture production with respect to phosphorus; with assistance from SEPA obtain a shortlist (approximately 10 lochs)

Objective 4 Laboratory determinations of physical and chemical characteristics of feed and faeces with respect to P, using a range of modern diets, complimenting current information available

Objective 5 By including results from laboratory investigations and the reviews, compare predictions of OECD type models with observations from monitoring surveys and refine as necessary

Objective 6 Inform the SEPA freshwater fish farming manual which is currently being developed by the regulator

 Project Summary:

The main objectives of this research are to (i) validate the existing OECD equation for the purpose of assessing the impact of fish cage production in Scottish freshwater lochs, (ii) characterise the physical and chemical nature of fish waste resulting from fish fed on a range of modern diets to obtain P budgets and (iii) assess the effect of using different feed constituents on fish waste, sedimentation and secondary uses of fish waste.
The project expects to achieve these objectives by (i) undertaking a review to establish the current knowledge on waste arising from freshwater production and the OECD equation and similar models, (ii) undertake laboratory experiments using modern diets and feeding practices to determine P budgets from feed and faeces (iii) compare historical data of total phosphorous (P) from SEPA monitoring data and operators commissioned reports in selected freshwater lochs with predictions of P from the current OECD equation and other similar models (i.e. Dillon and Rigler, 1974).

Results from the laboratory experiments will validate the important parameter of 10 kg P per tonne fish produced currently used, so revised predictions can be made using the data from modern feeds. By examining a time series of P for each selected loch, predictions will be made before and after aquaculture production commenced. Information on other P sources such as those from forestry will be sought from the PLUS model used by SEPA. The project is expected to inform the draft SEPA freshwater fish farming manual. Validation of the OECD equation will be a desk study utilising the largely unused resource of monitoring data from lochs where aquaculture is important. The project will take account of the recommendations expected from a SEPA data quality review on pre-2002 P monitoring data.