Fish for human consumption are often filleted and frozen before transfer to the market.
The present data refer to filleting of white fish such as codfish and flatfish and oily fish such as herring and mackerel. The main processes are following: 1) pre-treatment (removal of ice, washing and eventually deheading, gutting and cutting of tails), 2) filleting at mechanical filleting machines, 3) eventually removal of skin, 4) trimming (removal of bones and defects, cutting into appropriate pieces), 5) packing, freezing and storage. Wastewater generated in Danish factories is usually treated in municipal wastewater treatment plants. Fish waste is usually converted into fish meal.
Data have been collected from Danish plants and from a few African and American plants in 1990-95 by Jespersen et al. (2001).
Main processes at the factories are included. Packaging is not included.
The figures vary considerably from factory to factory, from fish specie to fish specie and even from fish to fish and the present data should only be seen as an order of magnitude.
Data presented here do not match very well with data presented by Ziegler (2000). Different system boundaries and different processes can possibly explain differences.
Jespersen C, Christiansen K and Hummelmose B (2001). Cleaner Production Assessment in Fish Processing. United Nations Environment Programm; Division of Technology, Industry and Economics. Agri-food forum.
Ziegler, F (2002). Environmental assessment of a Swedish, frozen cod product with a life cycle perspective. A data report. SIK - Institutet för Livsmidel och bioteknik. SIK report no. 696.
Data URL: http://www.lcafood.dk/processes/industry/filletingfish.html