Within the Fisheries Agency’s Project Promoting the Multifunctional Roles of Fisheries (2021–2025), there are activities of groups working on the restoration of declining seaweed beds predated by marine animals. Reports of those groups’ activities on the web were obtained and analysed. As a result, the decline of seaweed beds was identified due to feeding damage in northern Japan by the northern sea urchins (Strongylocentrotus nudus), in central and west Japan by purple sea urchins (Anthocidaris crassispina) and mainly in western Japan by long-spined urchin Diadema species as well as feeding damage in western Japan by herbivorous fish (Siganus fuscescens, Calotomus japonicus and Kyphosus bigibbus). These were attributed to an increase in water temperature during the winter months, which expanded the distribution area of the herbivorous animals, and to feeding damage during the seaweed growth period in the winter months. Other causes include a decrease in the number of coastal fishermen due to the ageing of the population, which has led to a decrease in the number of sea urchins and other species collected and an increase in sea urchin population density, as well as a decrease in the number of small set nets and gill nets used to collect herbivorous fish. Efforts to combat these feeding problems are also presented.