Providing evidence to improve practice

Individual study: Effects of husbandry on prevalence of amoebic gill disease and performance of reared Atlantic salmon (Salmo salar L.)

Published source details

Douglas-Helders G.M., Weir I.J., O'Brien D.P., Carson J. & Nowak B.F. (2004) Effects of husbandry on prevalence of amoebic gill disease and performance of reared Atlantic salmon (Salmo salar L.). Aquaculture, 241, 21-30


This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.

Alter cage size Sustainable Aquaculture

In 2000, a replicated study in Tasmania, Australia (Douglas- Helders et al., 2004) found higher levels of amoebic gill disease salmon, Salmo salar, stocked in 60m diameter round cages compared to those in 80m diameter cages. Levels of amoebic gill disease were 47% and 22%, respectively. Two cages with a diameter of 60m and three of 80m diameter were used for the study. Average biomass per pen was 2337 kg for the 60m cages and 2806 kg for the 80m cages. Monthly samples were taken from August to November. Signs of clinical disease were assessed using the routine Tasmanian salmon farmers gill assessment method.

 

Establish fallowing to reduce parasites/disease Sustainable Aquaculture

A replicated study from 2000- 2002 in Tasmania, Australia (Douglas-Helders et al. 2004) found no difference in mortality from amoebic gill disease (AGD) in Atlantic Salmon using the method of fallowing cages. Cumulative mortality at the end of the trials was 2.06% for the rotated cages and 2.88% for the stationary cages which was not significantly different in both years of the experiment. The fallowing period in different cages ranged from 4 to 97 days and the experiment was repeated in 2 growing seasons (December to March 2000/2001 and December to April 2001/2002). Average biomass per pen was 15,026 kg and 20,304.4 kg for the stationary treatment groups in the two seasons respectively. Average biomass for the rotated pens was 17,115 kg and 21,000.9 kg per pen. Signs of clinical disease were assessed monthly using the routine Tasmanian salmon farmers gill assessment method by examining at least 20 fish for the presence of AGD.

Bathe in freshwater Sustainable Aquaculture

Between 2000 and 2002, a replicated, controlled study in Tasmania, Australia (Douglas- Helders et al., 2004) found similar levels of amoebic gill disease in groups of salmon, Salmo salar, that had undergone freshwater bathing compared to those which had not. By the end of the study, amoebic gill disease occurred within 35% of fish within both groups. Monthly samples were removed from salmon in three groups receiving freshwater baths and three un-bathed groups. Average biomass per pen was 11, 663 kg for bathed groups and 20, 929 kg for un- bathed groups. Signs of clinical disease were assessed monthly using the routine Tasmanian salmon farmers gill assessment method