The focus of the studies ranged from single farms (Aubin
et al. 2009; Ayer and Tyedmers 2009) to small samples of
each farming system (Phong 2010), to aggregated industry
averages representing significant parts of national outputs
(Pelletier et al. 2009; Pelletier and Tyedmers 2010).
However, the quality of foreground data available for
aquaculture systems often depends on the intensity of
the system and the region of data collection. Highly
intensive systems, such as land-based salmon systems,
often keep more complete records of all inputs and outputs,
while only general estimations are available for most
extensive pond systems in rural areas. Accessibility to
feed inventories may, moreover, be subject to the scale
and nature of the feed mill, as exact mixtures of ingredients
often are held confidential. Site-specific measurements are,
moreover, dependent on the resources available. The articles
offer limited reporting on other environmental flows beyond
nutrient budgets (including methane, nitrous oxide emissions,
copper-based anti-fouling agents, antibiotics, etc.).