Xin Liu

As the world’s largest producer of fish, China has faced significant challenges in developing its fisheries. Over the past four decades, China has implemented and adjusted multiple regulations and measures to reverse the decline of aquatic resources and achieve sustainable fisheries. This study analyzes the production trends and efforts during the period 1980–2019, highlighting the key features of and structural shifts in China’s fisheries. Our results reveal a significant shift in seafood production from capture to aquaculture and from offshore to inshore waters. Moreover, China’s fishery policy has transitioned from resource exploitation to ecological conservation, with aquaculture production in 2019 being nearly 38 times higher than that in 1980. However, not all the management measures have been successful; for example, the “Dual Control” policy failed to achieve its goals. Despite this, some measures that require adjustments, such as the “Aquatic Germplasm Resource Reserves” and “Nature Reserve for Aquatic Animals and Plants” policies, show promise for further improving the sustainability of China’s fisheries, particularly if the focus is on marine resources.

Marine oil snow (MOS) potentially forms after an oil spill. To fully understand the mechanism of its formation, we investigated the effects of suspended particles (SP) and dispersants on MOS formation of crude oil and diesel oil by laboratory experiments. In the crude oil experiment, the SP concentration of 0.2 g L^–1 was more suitable for crude oil MOS formation. The addition of dispersants significantly stimulated N and TV during MS/MOS formation of SP at 0.4 g L^–1 and 0.8 g L^–1 concentration (p < 0.05). Without SP, the dispersants also stimulated crude oil MOS formation. Furthermore, the concentration of SP had a significantly positive effect on the reduction of the total amount of N-alkanes (p < 0.05). In the diesel oil experiment, after adding dispersants to diesel oil, the maximum N, D_m, and TV values at a SP concentration of 0.2 g L^–1 were significantly higher than those at 0.4 g L^–1 and 0.8 g L^–1 (p < 0.05). Besides, we found that dispersants stimulated MOS formation in diesel oil at a SP concentration of 0.2 g L^–1. However, the dispersants had an inhibitory effect on diesel oil MOS formation without SP. Notably, the MOS formed by diesel oil appeared white, unlike the black MOS associated with crude oil. These findings are important for the environmental impact of oil spills and elevated SP concentrations.

Laboratory experiments were conducted to study the effects of oil spills and dispersants on the growth of the red tide organism Chaetoceros sp. Crude oil produced from the Chinese Bohai Sea, diesel oil, and the chemical dispersant (GM-2) produced in China were added into Chaetoceros sp. cultures. The results showed that both crude oil and diesel oil could enhance the growth of Chaetoceros sp. Data were analyzed by one-way ANOVA, and the confidence interval was 95%. At a concentration of 20 mg L⁻¹ crude oil and a concentration of 10 μL L⁻¹ diesel oil, Chaetoceros sp. bloomed to 1.57 × 10⁵ cells mL⁻¹ (p < 0.01) at day 14 and 3.55 × 10⁴ cells mL⁻¹ (p < 0.05) at day 10, respectively. A concentration of 10 μL L⁻¹ diesel oil stimulated the specific growth rate for Chaetoceros sp. of 0.49 d⁻¹ over 10 days. The specific growth rate of Chaetoceros sp. with 20 mg L⁻¹ crude oil alone was 0.46 d⁻¹ over 14 days. However, the mixture of oil and dispersant did not enhance the growth of Chaetoceros sp. as significantly as oil alone. These results implied that oil spills in coastal waters can stimulate Chaetoceros sp., and the specific dispersant GM-2 applied following oil spills may be unlikely to further enhance the growth of Chaetoceros sp.

Between 1973 and 2017, evidences of red tide outbreaks and oil spill accidents in the Chinese coastal waters were collected. Statistical analysis and multiple regression models were used to determine the relationship between the red tide and the oil spill. Major findings reveal that (1) the frequency of red tides positively correlates to the number of oil spills and the volume of oil spilled as well; (2) the higher percentage of small spills (< 7 tonnes) are more likely to enhance the outbreaks of red tides; (3) both EI Niño and storm events do not show any relationship with red tides; and (4) more severe oil spill with penalty recorded implies a higher possibility to trigger the red tide afterwards. Therefore, oil spill contingency management focusing on small oil spills and mitigating their spill effect by physical measures could be of benefit to decrease the frequency of red tides significantly. For example, it is suggested to carry out physical combat instead of chemical dispersants to remove the spilled small oil in the shallow coastal areas for reducing the outbreak risk of red tides after the oil spill.