The world's fish catch is of the order of 75 million tons per year, but only about 1% of man's food is fish, although 10% of his animal protein intake is fish protein. The fraction of the annual catch used for reduction to fish meal and oil is about one third.
The fishmeal and oil industry, which started in northern Europe and North America at the beginning of the 19th century, was based mainly on surplus catches of herring from seasonal coastal fisheries. This was essentially an oil production activity; the oil finding industrial uses in leather tanning and in the production of soap and glycerol and other non-food products. The residue was originally used as fertilizer, but since the turn of this century it has been dried and ground into fish meal for animal feeding. In fact, one definition of fish meal is that it is a solid product, ground, that has been obtained by removing most of the water and some or all of the oil from fish or fish waste (Windsor, 1971). Its main use is in the diets of poultry, pigs and fish which need higher quality protein than does other farm stock, such as cattle and sheep.
Some doubts have been expressed that the world fish catch can be increased substantially; a figure around 100 million tons being regarded as a reasonable maximum. The first aim should be to produce fish for direct human consumption and there will be considerable pressure to reserve the extra production for human feeding. Only where it is uneconomic or impracticable should the catch be reduced to fish meal and oil. Ninety percent, however, of the fish that are currently reduced to fish meal and oil, the so-called industrial fish (menhaden, sand-eel, sardine, anchoveta, pout, etc.) are presently unmarketable in large quantities as human food. Much of the increased catch will be previously unexploited resources of unknown and perhaps unpalatable species and will thus be available for reduction. Apart from unpalatability, the reasons why this portion of the catch cannot be used for direct consumption include the facts that the fish are too small or break down or turn rancid too quickly for economic storage and subsequent heading, gutting, cleaning and processing. Turning high quality fish into fish meal and oil should not be encouraged. It is obviously more efficient, however, in a protein-hungry world to harvest the unacceptable species for feeding to animals, subsequently consumed by man, than to leave them unharvested in the sea.
Small oily fish are the mainstay of the fishmeal and oil industry. Even in frozen storage these fish turn rancid rapidly unless special and expensive precautions are taken. With present knowledge they can be used best by reducing them to fish meal for animal feeding and using the oil for direct human consumption in products such as margarine. There is a good demand for high quality fish meal and oil and production can be highly remunerative if suitable raw material is available. The industry can also utilize the offal - from filleting, gutting and other fish processing operations - which often poses disposal problems.
The most efficient course would be to feed the powdered products resulting from reduction directly to humans. This introduces the technology of fish protein concentrates (FPC). Direct feeding reduces the losses of cycling through poultry or pigs, which may take 3 kg of fish to produce 1 kg of edible chicken or pork, and also the losses involved in preparing fish for direct consumption. A fillet may contain only half the protein of the original fish after heading, gutting, filleting and skinning.
The production of FPC is within the capacity of the fishmeal and oil industry. There are problems as the hygienic requirements must naturally conform with those for human food. The fish must be fresh and sound and the plant must be easy to clean and sterilize after use. These are technological problems and although the solutions are expensive, the industry already possesses the design and organizational expertise. Two types of FPC have been and are being produced: a type A, with a fat content of less than 0.5% and a type B, with a fat content of less than 10%. The major problems of using FPC are social rather than technological; these are the difficulty and expense of incorporating new powdered products in the diet. FPC type B tastes fishy after production and "fishmealy" or rancid after storage, because most of the flavour is in the oil fraction. FPC type A is flavourless, but the removal of the oil, by solvent extraction, is expensive. In some areas, the rancid flavours are accepted as they are similar to those of traditional products. FPC must also be milled finely as it has little water holding capacity and would taste gritty when incorporated in food; this process is expensive. It is hoped that technological solutions to these problems will be developed and that FPC for human feeding can be made available at competitive prices. Meanwhile, the search for socially acceptable methods of incorporating it in food must go on. For example, type A can be chemically refined to impart functional capacities (water holding, jelling) to the powder. This raises the cost, but it is nevertheless cheaper than meat and can be used profitably as a meat extender, for instance, in sausages. From the above, it can be seen that the production of FPC is an enterprise which should be embarked upon only when a ready market for the products has been established.
The industry can make a valuable contribution to human nutrition both directly and indirectly. Wherever there is an abundance of fish that, for one reason or another, cannot be used for direct human consumption, the establishment of a fishmeal industry should be strongly encouraged and assisted, not least as a start to rational utilization. However, the uninitiated should beware of trying to start an industry without proper planning and with inexperienced staff or inadequate equipment.
The purpose of this document is to explain the complexity of the industry and to provide information on the planning and operation of a fishmeal and oil industry. The production of meal and oil is a sophisticated process requiring considerable skill and experience. The products will meet commercial and international standards only if they are manufactured under hygienic conditions in properly operated and controlled plants.