Body size estimation method for seasonally growing farmed yellowtail Seriola quinqueradiata in an aquaculture net cage using a stereo camera

Abstract

To determine the optimal method for monitoring the size distribution of cultivated yellowtail growth, we employed three different approaches: capture measurement, manual measurement using stereo cameras, and automatic measurement through stereo camera-based image recognition technology. Conventional capture measurements showed inadequate prediction interval owing to limited sample size, preventing accurate assessment of growth. Both manual and automatic camera measurements successfully conformed to a growth model exhibiting periodicity. The expected values derived from each model closely matched with the mean of landings conducted at the end of the study. However, the 95% prediction interval for manual measurement with cameras was comparable to that for the landing measurement, whereas the prediction interval for the automatic measurement with cameras was overestimated. Additionally, the growth rate of farmed yellowtail demonstrated seasonal fluctuations. Notably, the mean obtained from a single automatic measurement with cameras, prior to landing, significantly deviated from the overall mean of all measurements. This suggests a potential risk associated with relying on accidental outliers in a single measurement. Therefore, it is crucial to employ a growth model unaffected by outliers in continuous measurements to ensure reliable predictions.