Abstract
Aquatic ecologists routinely count animals to provide critical information for conservation and management. Increased accessibility to underwater recording equipment such as action cameras and unmanned underwater devices has allowed footage to be captured efficiently and safely, without the logistical difficulties manual data collection often presents. It has, however, led to immense volumes of data being collected that require manual processing, and thus significant time, labour and money. The use of deep learning to automate image processing has substantial benefits but has rarely been adopted within the field of aquatic ecology. To test its efficacy and utility, we compared the accuracy and speed of deep learning techniques against human counterparts for quantifying fish abundance in underwater images and video footage. We collected footage of fish assemblages in seagrass meadows in Queensland, Australia. We produced three models using an object detection framework to detect the target species, an ecologically important fish, luderick (Girella tricuspidata). Our models were trained on three randomised 80:20 ratios of training:validation datasets from a total of 6,080 annotations. The computer accurately determined abundance from videos with high performance using unseen footage from the same estuary as the training data (F1 = 92.4%, mAP50 = 92.5%), and from novel footage collected from a different estuary (F1 = 92.3%, mAP50 = 93.4%). The computer’s performance in determining abundance was 7.1% better than human marine experts, and 13.4% better than citizen scientists in single image test datasets, and 1.5% and 7.8% higher in video datasets, respectively. We show that deep learning can be a more accurate tool than humans at determining abundance, and that results are consistent and transferable across survey locations. Deep learning methods provide a faster, cheaper and more accurate alternative to manual data analysis methods currently used to monitor and assess animal abundance and have much to offer the field of aquatic ecology.
Highlights
The foundation for all key questions in animal ecology revolves around the abundance, distribution, and behavior of animals
We used the F1 score and mAP50 values to assess the performance of the computer model
F1 varied only 0.9% from 2,000 annotations to 6,000 annotations compared to an increase of 3.1% by mAP50 at the same annotations
Summary
The foundation for all key questions in animal ecology revolves around the abundance, distribution, and behavior of animals. Collecting robust, accurate, and unbiased information is vital to understanding ecological theories and applications. The development and availability of these devices can provide a more accurate and cheaper method to collect data, with reduced risk to the operator (Hodgson et al, 2013). Under these circumstances, they can increase sampling accuracy as well as replicability and reproducibility (Weinstein, 2017), which form the basis of a sound scientific study (Leek and Peng, 2015).
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