Analysis of transaction records of live freshwater finfish in China: A case study of customers' claims of fish mortality using cross-classified modeling

Customers of finfish in China place a high priority on healthy fish at the point of sale but factors that increase the risk of morbidity and mortality during transportation have had limited study. We designed a case study to investigate variation of mortalities claimed by customers receiving fish at markets with above-normal mortalities. We used daily transaction records of the 3 species transported from a company located in Guangdong province to its destination markets in Beijing between April and July 2013: largemouth bass (Micropterus salmoides), Chinese perch (Siniperca chuatsi), and longsnout catfish (Leiocassis longirostris). We quantified magnitudes and patterns of weekly mortalities of transported fish, and used cross-classified random-effect modeling to explore variation and clustering of fish mortality claims at wholesale destinations. Random effects for customer and market-week were interpreted by variance partition coefficients (VPC) and intraclass correlation coefficients (ICC). A significant fixed effect of market was found in the model of mortality claims for longsnout catfish (p < 0.05), and changing patterns of VPC and ICC suggested that customers ordering longsnout catfish had more variation in claims than those ordering the other 2 species. Our findings indicate a need for better customer communication for live fish transportation and a need for detailed measurements during the process including physiological factors and transportation conditions, to better understand their role in reported mortalities.