To establish a non-contact method to monitor the growth of masu salmon, Oncorhynchus masou, we filmed free-swimming farmed masu salmon in a sea cage using a stereo camera. Specifically, we released masu salmon at 1 and 3 years of age before and after spawning, respectively, into two sea cages installed in Matsumae-cho, Hokkaido, Japan. Individuals aged 1 and 3 years were reared for 202 and 221 days, respectively, in both groups, and fork length was measured using a stereo camera approximately every month from 10 December 2021. We observed an estimated growth of 21.2–31.7 cm and 36.8–40.6 cm for 1- and 3-year-old individuals, respectively. Both the predicted values and 95% prediction intervals of the growth curves for the two fish net cages were similar to the results of direct measurements after capturing the fish for landing. We observed an increase in the body sizes of the 3-year-old fish after they were allowed to spawn in sea cages; however, estimating their survival rates remained a challenge. This study allowed for a non-contact estimation of the size distribution of vulnerable for rubbing masu salmon cultured in sea cages.

This study explored the practical condition of manual fish sorting line at Matsuura local wholesale market, investigating the factors that are to be watched closely the progression toward advanced mechanization. Focusing on manual fish sorting line a part of large fish sorting machines used in purse-seine fisheries, this study highlighted a critical issue in the manual sorting section of the sorting line. Specifically, sorting machine operations were halted when the flow of fishes per second at a specific workstation surpassed 1.5 times the laborer’s sorting capacity. Addressing this challenge necessitates optimizing fish numbers on the manual sorting line to align with laborers’ sorting capabilities. Potential solutions include introducing splitters for efficient sorting or relocating laborers from workstations with lower fish flow. This proactive approach to identifying and addressing issues is vital not only for operational optimization but also for the development of innovative technologies, such image recognition–based fish sorting. It is expected that the analysis of such labor-intensive manual work in fishing will be utilized for more advanced mechanization and promote technological development.

In Japan, as the population declines and ages, there is a need for work style reforms such as improving labor productivity. The revised Fisheries Act was enacted in 2020, and the Act on Ensuring the Proper Domestic Distribution and Importation of Specified Aquatic Animals and Plants the Act on Proper Distribution of Fisheries was enacted in 2022, and fisheries policies centered on resource management, prevention of poaching, and proper distribution have begun. Under these circumstances, there is a need for new ways to manage and operate fishing ports and markets. For more than 20 years, fishing ports and fish markets in Europe have been working to save time and labor, to increase sales volume, value and price, and to improve resource management and traceability by computerizing sales operations. The author has clarified, by surveying fishing ports and fish markets in Europe and analyzing EU regulations and other literature, that the utilization of ICT can improve productivity and add value, and that fishing ports and fish markets can function as bases for resource management. To promote the ICT utilization in fishing ports and markets of Japan, implementing electronic auctions, transmission of information from fishing ports and fish markets, and one-stop services are the issues to be solved. Computerization of sales operations, including online auctions, allows more buyers across regions and borders to participate in auctions, creating functionally-integrated markets, virtual markets, and widely-collaborated/connected markets, saves time and labor, and contributes to expanding sales lots and realizing competitive prices.