Distribution of resources in the coastal waters of Qingdao and its relationship with environmental factors.

, with strong reproductive capacity and rapid growth, is an important nearshore fishing target in Qingdao. The distribution characteristics of resources in Qingdao and their influencing factors are largely unknown, which is detrimental to the protection and utilization of these resources. Based on the bottom trawl survey data of fishery resources carried out in the coastal waters of Qingdao during the summer and autumn seasons from 2018 to 2022, in combination with the data of environmental and spatial factors such as bottom seawater temperature, bottom seawater salinity, water depth, longitude and latitude, we analyzed the spatio-temporal variations of resources in this sea area, and the relationship between the distribution of resources and related factors using the random forest model. There were interannual variations in the resource density of in the coastal waters of Qingdao. During the study period, the resource density of presented a trend of decline-rise-decline. The highest densities of both adult and juvenile resources (31.33 and 48.09 kg·km) appeared in 2021, while the lowest densities (7.96 and 8.69 kg·km) occurred in 2022. The average proportion of juvenile resource density generally exhibited an upward trend. The distribution of resources in the coastal waters of Qingdao exhibited certain regional disparities and was concentrated in the southwestern and northeastern area of the surveyed sea. Juveniles were distributed each year within the bay area in the northeastern area of the surveyed sea, and no juveniles were found in Jiaozhou Bay over the years. Adults were mainly distributed in the peripheral waters of the bays in the southwestern and northeastern area of the surveyed sea. Bottom water temperature and bottom salinity were the main factors influencing the distribution of juveniles, while longitude, depth, and latitude were the main influencing factors of adults. The suitable water temperature range for juveniles was 23-25.5 ℃, with 23 ℃ for adults. The optimal salinity for juveniles was 30.5, with 31.5 for adults. Both juvenile and adult were distributed in shallow waters within 30 meters.