Mariculture is a well-known high-risk industry. However, mariculture insurance, which is an important risk management tool, is facing serious market failure. An important reason for this market failure lies in the unsound premium rate and pricing method. Due to a lack of long-term yield data, empirical rates are often adopted, but this adoption can lead to a high loss ratio. This paper provides an improved method for premium computation of mariculture insurance using an information diffusion model (IDM). An example of oyster insurance in China shows that, compared with the traditional pricing approach, the IDM can greatly improve the accuracy and stability of premium rate calculations, especially in cases of small samples.

This study aims to identify the overall level of China’s sea use efficiency (SUE) from 2006 to 2018 as well as regional differences and dynamic changes The super-efficiency weighted slacks-based measure (Super-WSBM) model and the global Malmquist–Luenberger (GML) index are employed. Results indicate that the SUE is at a medium-efficiency level. The inspection period revealed a decline period (2006–2008), a steady increase period (2008–2013), and a rapid increase period (2013–2018), exhibiting a “checkmark” type of growth. SUE has significant regional differences, and the degree of polarization has increased. Shanghai, Guangdong, and Shandong are high-efficiency regions, but unlike Shandong, which has experienced a rapid growth, the SUE of Shanghai and Guangdong has declined to varying degree, in Shanghai being particularly significant; Jiangsu and Tianjin are medium-efficiency regions, and SUE has experienced a rapid growth; Fujian, Hebei, and Zhejiang are inferior-efficiency regions, and SUE has slightly increased; Liaoning, Hainan, and Guangxi are low-efficiency regions. Except for a slight decline in Hainan, Liaoning and Guangxi experienced small increases. Thus, a sea use policy must be formulated on the basis of local conditions to promote the coordinated development of the marine economy. Moreover, the negative external impact of sea use on the marine environment must be observed, and marine resources within the range of the sea must be utilized.

The high-quality development of China’s fishery economy serves as its core objective, with robust financial support playing a pivotal role. This study employs provincial panel data spanning 2005 to 2020 and utilizes the entropy method to evaluate the level of high-quality development in China’s fishery economy across three dimensions: fundamental security, sustainability, and comprehensive efficiency. From the perspectives of formal and informal finance, it compares their support effects on different aspects of high-quality development in China’s fishery economy, while also exploring the mechanisms underlying these effects by considering factors such as industrial uncertainty and economic scale. The findings indicate that, overall, the support provided by both formal and informal finance for high-quality development in the fishery economy is insufficient. Further analysis reveals a significant threshold effect of fishery economic scale, with turning points at 108.44 billion CNY and 232.98 billion CNY for formal and informal finance, respectively. For higher-level indicators, such as sustainability and comprehensive efficiency, formal and informal financial systems demonstrate complementary roles, depending on the scale of the regional fishery economy. Furthermore, industrial uncertainty serves as a significant mediating factor only for formal financial support, with the levels of sustainability and comprehensive efficiency most affected.