Environmental impact of a salmonid farm on a well flushed marine site: I. Current and water quality

The culture of yellowtail kingfish Seriola lalandi in South Australia is one of the most rapidly growing aquaculture sectors in Australia. To date, there is a paucity of information on the environmental impacts of this industry, due to its relatively small size in comparison to other industry sectors. Here, we report on a study examining the response of a range of environmental variables to yellowtail kingfish aquaculture in Fitzgerald Bay, northern Spencer Gulf, South Australia. The clearest response occurred in several chemical variables, with an 81% increase in ammonia concentrations adjacent to cages relative to controls, increased sediment organic carbon (7 to 46%) and increased porewater phosphorus in the sediments (80 to 3077%). While there were also statistically significant effects on infaunal and epifaunal assemblages, results for both groups were equivocal because of high small-scale variability. For the infauna, assemblages at the sites furthest from cages tended to be similar to those adjacent to cages, while those at intermediate distances differed. No impacts were detected on phytoplankton, or on seagrasses (although the latter only occurred > 250 m from any aquaculture cage). The lack of clear responses in the biotic datasets is probably related to the relatively low production levels (< 2000 t yr -1 at the time of the study), although the responses in the chemical variables provide a valuable early warning as production increases.

Section: Water Column Impactsmentioning

confidence: 43%

Environmental effects of yellowtail kingfish aquaculture in South Australia

Tanner¹,

Fernandes²

2010

“…For cage aquaculture studies in developed coastal regions, it may be extremely difficult to find reference sites, remote enough from other aquaculture operations or other anthropogenic sources, while still reflective of farmexposed hydrodynamics (Troell et al 2003). Where baseline data are unavailable, sampling of multiple reference sites can be a powerful assessment tool to help ensure ambient spatial variability is captured (Fernandes et al 2001, Merceron et al 2002, Yucel-Gier et al 2007, Rodríguez-Gallego et al 2008. However, many studies have only a single reference location, presumably due to practical constraints.…”

Section: Data Analysis and Interpretationmentioning

confidence: 99%

“…The speed at which current passes through fish cages dictates the volumetric exchange (flushing) and thereby dilution potential (Merceron et al 2002, Reid & Moccia 2007, Middleton & Doubell 2014. Sampling regimens are often based on site hydrodynamics, and benefit from previous knowledge of current flows.…”

Section: Physical Processesmentioning

confidence: 99%

Discrete water quality sampling at open-water aquaculture sites: limitations and strategies

Jansen¹,

Reid²,

Bannister³

et al. 2016

While environmental performance of cage-based aquaculture is most often monitored through benthic conditions, there may also be requirements that necessitate discrete, pelagic sampling. In the pelagic realm, adequately capturing the spatial and temporal dynamics of interest and attributing causality to aquaculture processes can be extremely challenging. Conditions are seldom ideal, and data adequacy concerns of discrete samples collected at open-water aquaculture sites are not uncommon. Further exploration of these challenges is needed. Herein, we aim to explore considerations for study design, analysis, and data interpretation of discrete pelagic sampling. As examples, we present 2 case studies where limited sampling occurred under conditions of complex pelagic dynamics. A Norwegian case study quantified particle abundance around salmon farms, and aimed to highlight the effects of spatial−temporal variation on sampling design, the need for inclusion of companion parameters, and the benefits of a priori and a posteriori data interpretation strategies. A Canadian case study collected discrete samples to measure ammonium concentrations with continuous current measurements at an Integrated Multi-Trophic Aquaculture (IMTA) farm, to explore issues of complex hydrodynamics, reference site suitability, sampling resolution, data pooling, and post hoc power tests. We further discuss lessons learned and the implications of study design, ambient conditions, physical processes, farm management, statistical analysis, companion parameters, and the potential for confounding effects. Pragmatic consideration of these aspects will ultimately serve to better frame the costs and benefits of discrete pelagic sampling at open-water aquaculture sites.

“…During intensive production of salmon in open cages, the discharges of organic wastes such as faeces and uneaten feed and inorganic nutrients such as ammonium (NH 4 + ) and phosphate ) are released directly into the environment and may cause negative ecological effects on the surrounding waters (Merceron et al 2002, Carroll et al 2003, Cheshuk et al 2003, Skogen et al 2009, MacDonald et al 2011. Particulate organic matter may accumulate in the sediments and cause changes in the benthic ecosystem (Carroll et al 2003, Stigebrandt et al 2004, Kutti et al 2007.…”

Section: Introductionmentioning

confidence: 99%

Chemical composition and release rate of waste discharge from an Atlantic salmon farm with an evaluation of IMTA feasibility

Wang¹,

Andresen²,

Handå³

et al. 2013

The carbon (C), nitrogen (N) and phosphorus (P) compositions of salmon feed, fish and faeces were studied at a salmon farm in Badstuvika (63°31' N, 9°9' E) in central Norway. These data were used to estimate the release rates of wastes from 2 salmon cages and the qualities of particulate wastes as food resources for integrated multi-trophic aquaculture (IMTA). About 38% of feed C, 43% of feed N and 24% of feed P were retained as fish biomass. About 62% of feed C, 57% of feed N and 76% of feed P were lost into the environment. Around 40% of feed C was respired as CO 2 , and 39% of feed N and 24% of feed P were excreted as dissolved inorganic nitrogen and phosphorus, respectively. About 19% of feed C, 15% of feed N and 44% of feed P were released as particles. The chemical composition of feed was independent of time (p > 0.05). The faecal C content increased with increasing fish weight (r 2 = 0.14, p < 0.05); however, other faecal chemical components showed no apparent relationships with fish weight (p > 0.05). Our results suggested that P digestibility of feed may be 30%, but more information is still needed to reach conclusions on this. The C content of faeces was 70% of that of feed and the N content of faeces was 50% of that of feed. The P content was far higher than that of feed. The lipid, docosahexaenoic acid and eicosapentaenoic acid contents of faeces were comparable to those of some phytoplankton species. The results suggested that both feed and faeces are adequate food for blue mussels and sea cucumbers co-cultured with salmon, and the nutrient content may meet their nutritional requirements.