Settling rate characteristics and nutrient content of the faeces of Atlantic salmon, Salmo salar L., and the implications for modelling of solid waste dispersion

Citation

Chen Y, Beveridge MCM & Telfer T (1999) Settling rate characteristics and nutrient content of the faeces of Atlantic salmon, Salmo salar L., and the implications for modelling of solid waste dispersion. Aquaculture Research, 30 (5), pp. 395-398. https://doi.org/10.1046/j.1365-2109.1999.00334.x

Abstract
Intensive cage aquaculture generates considerable quantities of waste, comprising both particulate uneaten food and fish faeces and soluble excretory products. Estimates from laboratory studies suggest that 25-30% of the dry weight of feed consumed, or 250-300 kg dry weight per tonne fish production, is voided as faeces ( Butz & Vens-Cappell 1982; NCC 1990). The recent introduction of high-energy or low-pollution commercial fish feeds, which have higher associated digestibilities, has resulted in a reduction in faeces production of the order of 10-25% ( Cho, Hynes, Wood & Yoshida 1994; Talbot & Hole 1994). In order to assess the impact of caged Atlantic salmon, Salmo salar L., farming on the marine environment and match production to site capacity, it is essential to know not only the quantities and composition of wastes but also their settling velocities and stability in water and the leaching rates of key nutrients, such as carbon and nitrogen. Despite this, there has been little research on fish faeces. In the present study, we determine faeces settling velocities and carbon and nitrogen composition when collected by hand-net, stripping and by dissection (trial 1) and determine the portion of the hind-gut that contains material representative of freely voided faeces potentially useable in nutrient leaching rate studies (trial 2).

Journal
Aquaculture Research: Volume 30, Issue 5