Comments on the Oyster Aquaculture Industry in China: 1985-2020.

Since the 1980s, China's oyster aquaculture has grown quickly in the past four decades, and it became the top mariculture species in China with an annual production of 5.23 million in 2019. Understanding the growth of oyster aquaculture in China is important to gain insights into successful long-term production. This paper attempts to decompose China's oyster aquaculture between trends and cycles by means of an HP filter, make a specific identification of the relevant factors according to the Cobb-Douglas production function, to summarize the objective law of yield fluctuations. Results suggest that from 1985 to 2011, China's oyster aquaculture experienced a development stage of "rapid rise - steady development". At this stage, it shows a slow growth trend, and the growth can persist for long periods of time. The improvement of consumption level driven by economic growth is the main facilitating factor to promote the oyster industry, export trade and oyster price are also critical, diseases and disasters did not exert much influence on the growth of China's oyster aquaculture. The biggest problem hindering sustainable development is the tragedy of the commons caused by the limitation of marine resources, the contradiction of development will become a thorny issue.

Erratum: Early Impact of COVID-19 Pandemic on the Molluscan Shellfish Supply Chain in China.

[This corrects the article DOI: 10.1016/j.ocecoaman.2021.105852.].

Early impact of COVID-19 pandemic on the molluscan shellfish supply chain in China.

A farm-level survey and a market survey were conducted in China to study the impact of the COVID-19 on the shellfish supply chain in the early stage of the pandemic in 2020. 114 farms of 36 cites participated in an online survey from mid-July to late August, and 23 markets in five cities were investigated from June to November. The series results are expected to provide an insight for the fisheries and aquaculture sector to mitigate the impact of the pandemic on participants in the shellfish supply chain and to improve of the ability of the government to respond to such events in the future. Shellfish farmers and sellers have experienced a sharp drop in profits, largely due to shrinking demand. Relying on local employees and suppliers, shellfish farming activities have rapidly resumed since the gradual reopening from February. Nevertheless, demand has been slow to recover due to public concern about contamination of seafood with the virus. Additionally, we analyzed the ability and attitude of farms of different size to cope with the pandemic and the plight of shellfish sellers, and discussed government supports for different size farms and improvements in seafood distribution channels.

Comparative analysis of profitability and resource use efficiency between Penaeus monodon and Litopenaeus vannamei in India.

The study aimed to highlight the profitability and production function analysis of Penaeus monodon and Litopenaeus vannamei in intensified shrimp farms in Gujarat (India). Two hundred and twenty (220) shrimp farm households were used to identify (principal component and cluster analyses) 8 clusters of management practices that reflected various scales of production intensity ranging from 0-2999 kg/ha/crop to 9000kg/ha/crop and above for both the species. The Cobb-Douglas production function, which relates production output to several independent input variables, was used to determine productivity. The budgeting analysis for both the species showed that more intensively managed farms performed more than the less intensive farm. Empirical results show feed as most significant input for Penaeus monodon and Litopenaeus vannamei seed and labor that affected production. Average net returns/ha/year for Penaeus monodon was $16313.13 and for Litopenaeus vannamei $41640.99. Aquaculture exhibited decreasing returns to scale for both the species and estimates on resource use efficiency revealed that in Penaeus monodon the resources were economically utilized and in case of Litopenaeus vannamei the output was likely to increase if more of seed and less of labor would have been used. The major constraint for the shrimp farmers was diseases which can be mitigated by optimum stocking densities and proper feed management.

A Solution for Sustainable Utilization of Aquaculture Waste: A Comprehensive Review of Biofloc Technology and Aquamimicry.

Biofloc technology (BFT) is gaining traction as a strategic aquaculture tool for boosting feed conversions, biosecurity, and wastewater recycling. The significant aspect of BFT is aquaculture with highest stocking density and minimal water exchange. It not only improves the water quality of a system by removing inorganic nitrogen from wastewater but also serves as a suitable feed supplement and probiotic source for cultured species. This technology is commonly used for shrimp and tilapia culture and can be used for both semi-intensive and intensive culture systems. Biofloc, when combined with formulated diets, forms a balanced food chain that improves growth performance. Nutrients in this system are continuously recycled and reused and form an efficient alternative system in aquaculture. In addition to the reduction in water exchange, it is also considered as a bio-security measure, since it prevents entry of disease from outside sources. Aquamimicry is an innovative concept that simulates natural estuarine conditions by developing copepods that act as supplementary nutrition especially for shrimp culture. The review highlights the process, significance, and development of BFT, its microbial interactions, nutritional value, transition from biofloc to copefloc, and concept of aquamimicry to sustainably improve aquaculture production.

Analysis on the relationship between fisheries economic growth and marine environmental pollution in China's coastal regions.

The rapid development of China's fisheries economy is accompanied by intensified marine environmental pollution over the period covered by this study. Based on data from multiple sources, this paper attempts to measure the relationship between fisheries economic growth and marine environmental pollution among China's coastal regions over the past 17 years. For this purpose, it firstly quantifies changes in fisheries economy and fisheries population. It then goes onto comparing the degree of changes in fisheries economy and marine environment. Finally, it depicts the relationship between fisheries added value (FAV) and polluted marine area (PMA) and between per capita net income of fishermen (PCNIF) and PMA ratio. Results suggest that.