Boom‐and‐bust production cycles in animal seafood aquaculture

Abstract

AbstractAlthough aquaculture has grown nearly exponentially over the last six decades, providing 31.6 million metric tons of animal seafood in 2015, its rate of growth has slowed over the last 15 years. Here, we use case studies, drawn mostly from Asian shellfish culture, to suggest that ‘boom‐and‐bust’ production cycles – periods of rapid growth followed by collapse – cause significant losses of seafood production and to illustrate the duration and repetition of boom‐and‐bust cycles. Next, using the global FAO database for aquaculture production from 1950 to 2015, we investigate whether boom‐and‐bust cycles occur more broadly and whether they are playing a role in the declining rate of global aquaculture production. Focusing on FAO production records with maxima before 2011, allowing time for collapse, we categorize production in each record, relative to its maximum value, as sustained, depleted, collapsed or lost. We find 278 of 453 records (61.4%) show collapsed or lost production, although production in most of these records comprises only a tiny fraction of global output. The top 30 records in the collapsed or lost categories do account for 2.4% of cumulative production over the 66‐year record of animal seafood aquaculture. We identify a strong association between short boom phases (5 years or less) and the probability that production will be lost and use this, as well as maximum annual production and year of maximum production, to model the probability of loss. Ecological limits and market problems are the most often discussed causes of boom‐and‐bust production cycles, but we focus, here, on disease as a major proximal cause of collapse and raise the hypothesis that inbreeding depression may often be an ultimate cause by exacerbating disease susceptibility.