Regulating the local environmental impact of intensive marine fish farming: III. A model for estimation of the holding capacity in the Modelling–Ongrowing fish farm–Monitoring system

• Published in: Aquaculture Vol. 234; no. 1-4; pp. 239 - 261
• Main Authors: Stigebrandt, Anders, Aure, Jan, Ervik, Arne, Hansen, Pia Kupka
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 03-05-2004; Elsevier Science
• Subjects: Animal aquaculture; Animal productions; Animal, plant and microbial ecology; aquaculture; Biological and medical sciences; deposition; diffusive boundary-layers; Earth and Related Environmental Sciences; Environmental impact; Fish farming; Fundamental and applied biological sciences. Psychology; General aspects; General aspects. Techniques; Geovetenskap och miljövetenskap; Invertebrata; Marine; Methods and techniques (sampling, tagging, trapping, modelling...); Modelling; MOM; organic-matter; oxygen-uptake; Pisces; sediments; waters; Fish farming; Modelling; MOM; Environmental impact; Marine environment; Vertebrata; Pisces; Pisciculture; Models; Aquaculture
• ISSN: 0044-8486; 1873-5622
• DOI: 10.1016/j.aquaculture.2003.11.029

A model has been developed for estimating the holding capacity of sites for fish farming. Expressed in terms of maximum fish production per month, the holding capacity is estimated with regard to three basic environmental requirements:(i)the benthic fauna at a farm site must not be allowed to disappear due to accumulation of organic material;(ii)the water quality in the net pens must be kept high;(iii)the water quality in the areas surrounding the farm must not deteriorate.All these requirements must be fulfilled, and the holding capacity is determined by the lowest of the three estimates. The fulfillment of requirements (i) and (ii) depends on local environmental properties such as water depth, the annual temperature cycle and the vertical distribution of current properties, and concentrations of oxygen and ammonium. It also depends on the maximum fish density per unit area, so the physical configuration of the farm is of importance. All these factors as well as feeding rate and feed composition are taken into account in the model.
The model comprises four sub-models which, for a given set of local environmental parameters, compute holding capacity according to these basic requirements. Given the feeding rate, feed composition and water temperature, a general fish sub-model adapted for domesticated Atlantic salmon computes the metabolism, growth and feed requirement of a specified fish stock. The fish model also computes emissions of particulate organic matter, i.e., uneaten feed and faeces. A dispersion sub-model computes the distribution of particulate matter from the net pens on the bottom for various sizes of pens and distances between them. A benthic sub-model computes the maximum rate of particulate matter sedimentation that will not result in the extinction of the benthic macro infauna. Water quality in the net pens is expressed as the lowest concentration of oxygen and the highest concentration of dissolved substances potentially harmful to the fish. These are computed by the water quality sub-model that needs input from the fish sub-model concerning the emission of dissolved substances and the consumption of oxygen due to respiration. The holding capacity according to requirement (iii) is computed by means of a previously published model.