Wild or farmed fish for human consumption?

Society has to face the nature of the choices available for feeding the human population of the future. One could consider that, in the development of agriculture, such choices have been made “unwittingly” many times in the past and agriculture dominates most terrestrial ecosystems world-wide.

The following example compares data for Arctic cod (Gadus morhua) from the northern Arctic ocean with that for farmed Atlantic salmon.

Like most wild fisheries species, Arctic cod is carnivorous and consumes large quantities of animal protein and energy. The standing biomass of cod in the Northeast Arctic is estimated at 2 million tons, which consumes some 6 million tons of prey fish, of which up to 1 million tons are small cod. The sustainable catch of adult cod is 0.7 million tons per annum, which yields some 0.25 million  tons of cod fillets.

Although paradoxical at first sight, a more viable alternative for society may be to reduce the population of cod and catch the prey fish instead. These could then be used directly to provide about 8 times the amount of food fish for human consumption than the current sustainable catch of Arctic cod. However, for the moment, there is insufficient consumer demand for the prey fish to make this a viable exercise.

An alternative use for the cod’s prey fish could be as a feed constituent for cultured fish, such as Atlantic salmon, rainbow trout, seabass or seabream. For salmon or trout, the 6 million tons of prey fish would yield sufficient fish meal to support a stock of some 0.9 million tons. This would yield some 2 million tons of salmon or trout each year, equivalent to 1.3 million tons of fillets.

This is 5 times more food for human consumption than the 0.25 million tons of cod fillets produced from the same amount of prey fish.