Official statistics on numbers of farmed fish are not available. Statistics on farmed fish production published by the Food and Agriculture Organisation of the United Nations (FAO) are given in tonnages and not numbers. Nor, unfortunately, does the FAO systematically publish mean weights of fish, which would enable numbers to be calculated from these tonnages.
This study estimates the annual number of farmed fish slaughtered for food using FAO aquaculture production tonnages and mean weights estimated from available fish size data (from a range of interent sources). From this it is estimated that between 37 and 120 billion* farmed fish are slaughtered globally each year, for which the midpoint is around 80 billion*.
Note that this estimate does not include non fish species e.g. lobsters and does not include the fish deaths arising in fish farms prior to harvest; in the capture of wild fish for feed or re-stocking; or from environmental impacts on surrounding wildlife. Nor does it include the numbers of fish farmed for use as bait, whose small production tonnages may comprise large numbers of fish due to their very small size of just a few grams.
The method used in this estimate is briefly outlined below and is similar to that used in the Study to estimate numbers of wild-caught fish. For full details and results see the fish count estimates page at Study to estimate numbers farmed fish.
Study to estimate numbers of farmed fish
There are three main parts to this estimate:
(1) fish for which the FAO reports aquaculture production tonnages in single species categories, e.g. Silver carp (Hypophthalmichthys molitrix), and for which a mean weight was estimated from available fish size data
(2) fish for which the FAO reports aquaculture production tonnages in multi-species categories and for which mean weights were estimated for the largest and smallest farmed species in the category (Tilapias nei)
(3) fish for which the FAO reports aquaculture production tonnages in totally general categories, e.g. Freshwater fishes nei (Osteichthyes), together with categories for which the species are given but for which a mean weight could not be estimated.
The first part comprises the single species categories for which it was possible to estimate a mean weight, and so estimate fish numbers. Where possible, estimated mean weights were obtained from average or normal harvest weight data but, where these were not available, typical or common weights were used.
The second part comprises the multi-species categories for which fish size data were available. To estimate the mean weight for a multi-species category, the mean weight was estimated for the smallest and largest farmed species in the group and combined as a range.
The third part comprises the species categories for which no estimated mean weight was obtained. The numbers of fish represented by these tonnages were estimated by extrapolating mean weight data from species for which a mean weight had been estimated.
* estimated range 36,734 million to 121,757 million (midpoint 79,246 million) rounded to 2 significant figures.