Potential environmental impact resulting from biased fish sampling in intensive aquaculture operations

Aquaculture contributes to global food security, producing over 70 million tons of fish and aquatic products annually. Protein rich fish feeds, together with labor costs are the most expensive component costs in aquaculture. Feed application is given as percent of fish weight and therefore, reliable biomass assessment is essential for profitable and environmentally sound aquaculture. Fish biomass estimates are typically based on sampling <2% of the fish population. The goals of this research were to estimate potential biases associated with fish sampling in recirculating aquaculture systems (RAS), and the potential economic and environmental implications of such biased estimations. The size of the biased sampling-based estimates of fish biomass in two cultured species was shown to be larger than what the confidence interval suggests, even after >20% of the population was sampled. Such biases, if indeed common, will most likely result in over/underfeeding, both entailing negative economic and environmental consequences. We advocate conducting similar studies with major cultured fish to generate "bias correction tables" for adjusting fish feeding rate to bias-corrected biomass. These will help reduce the potential economic losses and negative environmental impacts of aquaculture practice.