Passive acoustic monitoring (PAM) has emerged as an effective tool for studying underwater soundscapes and monitoring marine organisms. In this study, the biological sounds of three fish species that mainly inhabit or occur in the Korean coastal oceans, brown croaker (Miichthys miiuy), Pacific cod (Gadus macrocephalus), and small yellow croaker (Larimichthys polyactis) were recorded using the PAM method. The possibility of automatic classification was evaluated using a deep learning-based convolutional neural network (CNN) model based on the measured data. The biological fish sounds were recorded using hydrophones in the sea cage environments. The three fish species data were converted into spectrogram images and used as input for training and evaluating the CNN model. Gaussian noise was added to the test data to simulate low signal-to-noise ratio (SNR) environments. The model achieved high classification performance, with F1-score of about 96% on raw data and about 77% accuracy under signal-to-noise ratio conditions. These results suggest that CNN-based models be adequate for fish sound classification, even in acoustically complex underwater environments. Applying CNN models to classify and detect fish sounds can improve the automation and efficiency of PAM-based acoustic analysis, thereby improving the monitoring of fish populations, resource assessment, and ecological management in the future.

Several studies have evaluated the effects of types of relative frequency and delay interval of knowledge of results(KR) on motor skill learning independently. The purpose of this study was to determine more effective types of KR relative frequency and KR delay interval for motor learning. Forty-six healthy subjects (15 female, 31 male) with no previous experience with this experiment participated. The subjects ranged in age from 20 to 29 years (mean=23.9, SD=0.474). All subjects were assigned to one of four groups: a high-instant group, a high-delay group, a low-instant group, and a low-delay group. During the acquisition phase, subjects practiced movements to a target (400 mm) with either a high (83%) or low (33%) KR relative frequency, and with either an instantaneous or delayed (after 8s) KR. Four groups were evaluated on retention (after 3min and 24hr) and transfer (450 mm) tests. The major findings were as follows: (1) there were no between-group differences in acquisition and short-term retention (p>0.05, (2) a low (33%) KR relative frequency during practice was as effective for learning as measured by both long-tenn retention and transfer tests, compared with high (83%) KR practice conditions (p<0.05), (3) delayed (8s) KR enhanced learning as measured by both long-term retention and transfer tests, compared with instantaneous KR practice conditions (p<0.05), and (4) there were no interactions between KR relative frequency and KR delay interval during acquisition, retention, and transfer phases. The results suggest that relatively less frequent and delayed KR are more effective types for motor learning than more frequent and instantaneous KR.ㅂ