144. The stocking density must allow fish to show most normal behaviour with minimal pain, stress and fear. Scientific research is needed on the effect of stocking density on fish welfare but it seems that 30-40 kg/m³ is too high a stocking rate for trout. Higher densities may be acceptable for short periods prior to slaughter and during treatment for disease and parasites.
145. Research should be undertaken urgently to determine acceptable maximum stocking densities taking account of factors referred to in paragraph 143 and including objective measures of the welfare of the fish. These results should be available within five years, at which point we expect to recommend the introduction of legislation to limit stocking densities.
146. Efforts should be made to monitor trout mortality accurately and to develop management methods and stocking densities which reduce it.