5.1 Current uses of krill
5.2 New products
5.4 Trends and future developments
The products of the krill industry have been reviewed by several works (Budzinski et al. 1985.; Eddie 1977; Everson 1977; Grantham 1977; Suzuki 1981) and these reviews have dealt with this topic in some detail. A more recent review (Suzuki and Shibata 1990) deals primarily with the use of krill for human consumption but also provides information fishing and processing technologies. We will concentrate on recent developments in fisheries products and their uses. For earlier accounts, the reader is referred to these reviews.
5.1.1 Human consumption
5.1.2 Sport fishing
5.1.3 Aquarium food
The Japanese Antarctic krill fishery, which takes most of the current catch, produces four types of product: fresh frozen (34% of the catch), boiled-frozen (11% of the catch), peeled krill meat (23% of the catch) and meal (32% of the catch). Yields in the manufacture of these products are 80-90% for fresh-frozen and boiled-frozen, 8-17% for peeled krill and 10-15% for meal (1995 figures, T. Ichii, Japan National Research Institute of Far Seas Fisheries, personal communication). The technology for producing each of these products has been described in earlier reports (Budzinski et al. 1985.; Suzuki 1981).
The use of krill for human consumption has been reviewed recently and the nutritional value of krill has been assessed (Suzuki and Shibata 1990). The Japanese Antarctic fishery produces boiled, frozen krill and peeled tail meat for human consumption and 43% of the catch is used in this fashion. Canned tail meat is no longer produced from the Japanese catch and all of the peeled tail meat is frozen in blocks on board. Information on other nations Antarctic krill fisheries is not generally available. A small amount of E. pacifica caught off Japan is also used for human consumption (Kuroda and Kotani 1994a). Although much effort in the past has gone into producing krill products for human consumption there have been few recent developments in this area.
A considerable percentage of the Japanese Antarctic krill catch is used for sport fishing bait. Fresh frozen krill comprises 34% of the total catch and of this 70% is sold whole as bait and 10% of this is used as chum for sport fishing. Kuroda and Kotani (1994a) suggest that there is little competition between Antarctic krill, E. superba and E. pacifica used for sport fishing, because smaller E. pacifica are used as chumbait (about 50% of total catch), whereas the larger E. superba are mostly used as a bait.
A small quantity of Antarctic krill is freeze dried for the home aquarium market. An estimated 50% of the catch of E. pacifica from the British Columbia fishery is used as aquarium food (Dave Barrett, Murex Aqua Foods Inc., Pers Comm.).
Currently, most of the krill caught in all the commercial fisheries is used for aquaculture feed. For Antarctic krill, 34% of the Japanese catch is fresh frozen of which 20% is used for aquaculture and 32% is used to produce meal which is used in fish culture; 50% of the Japanese E. pacifica catch and much of the Canadian catch of this species is used as an ingredient in feed for fish culture.
There is considerable literature on the nutritional value of krill in cultured fish diets. Storbakken (1988) reviewed the literature on the value of a variety of species of krill as aquaculture feed. He concluded that krill of all species examined provide a nutritious diet and can be used successfully as a source of protein, energy and flesh pigmenting carotenoids. He also alludes to the growth promoting properties of krill amino acids and to its effect as a feeding stimulant. Krill-fed salmon were also found to have a superior taste and did not significantly accumulate fluoride from the krill exoskeletons in their flesh. This paper should be consulted for a review of the earlier literature.
Carotenoids are found in krill at around 30 ug g--1 and appear to deteriorate rapidly during storage if not refrigerated below 0°C. (Czerpak et al. 1980; Kolakowska 1988). Up to 50% of the Japanese E. pacifica catch is used as an ingredient in feed of fish culture to add reddish colour to the skin and meat of fishes such as red sea bream (Pagrus major), coho salmon (Oncorhynchus kisutch), rainbow trout (Salmo gairdnerii), yellowtail (Seriola quinqueradiata) and others (Kuroda 1994) because E. pacifica contains large amounts of carotenoid pigments, especially astaxanthin. Extracts from Antarctic krill have also been successfully used as pigmenting agents for yellowtail (Seriola quinqueradiata) and coho salmon (Oncorhynchus kisutch) (Arai et al. 1987; Fujita et al. 1983). As Odate (1991) pointed out, Japanese people love red colour as an indication of good luck and use red sea bream and lobsters as an offering in celebrations. Moreover, a reddish colour in fish meat is thought to stimulate the appetite.
Krill are known to have a positive effect on the feeding behaviour of some fish. Shimizu et al. (1990) showed that diets supplemented with krill meal stimulated feeding behaviour in sea bream (Pagrurus major) and that this effect was probably due to the presence of the amino acids proline, glycine and glocosamine. Not only do krill diets seem to stimulate feeding, they seem to promote growth in some species of fish (Allahpichay and Shimizu 1985). The growth promoting factors seem to be steroids located in the cephalothorax region, thus are available in non-muscle meal. The use of krill (E. pacifica) as a food source has also contributed to increased disease resistance in hatchery reared salmon smolts (Haig-Brown 1994). This has been attributed to the early development of the immune system when using krill as a food source.
The nutritive value of Nyctiphanes australis has recently been assessed with regard to its possible use as an aquaculture feed (Virtue et al. 1995). They found that N. australis contained, on average, 52% protein and up to 9.5% lipid on a dry weight basis. The lipid content of N. australis was marked by the presence of high quantities of unsaturated fatty acids with a mean w3 fatty acid content of 49% of the total fatty acid content. Carotenoids were present at levels of up to 320 u g-1 and were mainly astaxanthin (79.5%). Fluoride levels were as high as those reported in other species of krill (up to 3507 u g-1).
5.2.2 Autoproteolytic precipitates
5.2.3 Krill as a food additive
5.2.4 Krill hydrolysate
5.2.5 Low-fluoride krill paste and krill protein concentrates
5.2.6 Krill as a source of chitin
5.2.7 Krill as a source of lipids
Krill of all species contain a wide range of biochemicals which are of nutritional and possible pharmaceutical value (Table 8).
Considerable Polish research has been carried out into producing krill precipitates using autoproteolysis, making use of the krill's high level of proteolytic enzymes to produce a high yield (80% protein recovery) concentrate (Kolakowski and Gajowiecki 1992). In the Polish process, whole krill are mixed with water and heated. The hydrolysate is centrifuged to remove the shells and the precipitate is coagulated. The final product has low fluoride content (<29mg kg-1), a protein content of 18-22%, fat <7% and a high level of carotenoid pigments giving the precipitate a pink-red colouration. This product is used mainly as a colorant and a flavourant additive to fish and other products for human consumption.
Freeze dried krill concentrate prepared from peeled tail meat is currently being marketed as a food additive and as a health food supplement by a Spanish company5. It is being advertised as having a number of useful properties such as high omega 3 fatty acid content, moderate caloric content, high nutritional value and ease of digestion. Antarctic Krill Concentrate is advertised as having a major revitalizing function on the organism and suggested uses as a dietary supplement include: use during pregnancy, lactancy, pre- and post-menopausal stages, growth, operative procedures, cancer prevention, radiotherapy, chemotherapy, syndromes of immunodeficiency and treatment of various nutritional disorders.
5 Information provided by: C. Falkenberg, Monteclaro Asesores, S.L.. Acacias 10, Monteclaro, 28223 Madrid, Spain.Krill concentrate is also being promoted as an agent that has direct application in:
· Cardiovascular medicine: diminishing the risk of myocardial infarction, angina pectoris thrombosis and arterial hypertension by preventing arteriosclerosis.Antarctic krill concentrate is advertised as containing important oligoelements, including antioxidants and minerals required to prevent cavities and osteoporosis. The recommended dose is approximately 5 grams per day. Antarctic krill concentrate is promoted as being 100% natural and free of any side effects, even when taken at higher doses. The omega-3 fatty acids in dehydrated krill products are reported to remain unaltered even if stored for longer periods, and retain all their beneficial properties.
· Gynaecology: pregnancy, lactancy, pre-and post-menopausal stages.
· Paediatrics: child and adolescent growth.
· Odontology: avoidance of cavities in teeth at all ages.
· Geriatrics: prevention of osteoporosis and deterioration of tissues.
· Traumatology: avoiding loss of osseous tissue.
· Dermatology: reconstruction of hair and nails, improvement of skin.
· Surgery: pre- and post-operative procedures.
· Oncology and cancer prevention.
· Sports medicine: athletes diets.
· Treatment of nutritional disorders: obesity and anorexia.
· The product is also suitable as a prescription for natural medicine.
Antarctic krill concentrate is produced as flakes or as loose powder with different degrees of granulation and has a light salmon pink colour and an excellent shrimp-like taste. It is promoted as an excellent natural colouring and flavouring agent which is effective even in small quantities when used in: soups, sauces, pasta, pies, doughs, vegetables, fish based recipes, rice dishes, etc. It is suitable for the manufacture of special dietary meals and growth food products and requires no special storage conditions.
A new product which uses the enzymes of krill to hydrolyse the krill and liquefy them, before pelletising and drying is being developed in British Columbia for salmon farming and may be applicable to krill fisheries elsewhere (Haig-Brown 1994) A Canadian firm, Biozyme, is producing these high value krill hydrolysate products using a proprietary process it has developed. These products are offered in liquid, concentrated, dried and frozen forms. The market for these products are in the animal and aquaculture feed industries (D. Saxby, Biozyme Inc., pers. comm.6).
6 D. Saxby, Seasource International Inc. 3650 Westbrook Mall, Vancouver, British Columbia, Canada V6S 2L2.
All species of krill so far examined contain high levels of fluoride in their shells (Nicol and Stolp 1991; Soevik and Breakkan 1979; Virtue et al. 1995) and this has proved a problem for producing products for human consumption and for many domestic animals (Budzinski et al. 1985). Despite the high fluoride levels of whole krill, they are, however, suitable for aquaculture feed (Storbakken 1988). There have been efforts made to produce low shell (hence low fluoride) products. Krill paste produced by traditional methodologies (Budzinski et al. 1985) and alkaline and acid processed krill protein concentrates have been produced in a low fluoride form by either organic acid washings or by simple water washings (Tenuta-Filho 1993). Using either treatment, fluoride concentrations of less than 21µg g-1 (dry matter) were obtained compared to untreated protein concentrates with values of 250 µg g-1 (dry matter) (Oehlenschlager 1981). These processes yielded high protein recovery and a product with sufficiently low fluoride concentrations for human consumption.
Krill have been promoted as a possible source of chitin and chitosan (Anderson et al. 1978) and considerable research has been carried out into the extraction of chitin from Antarctic krill (Breski 1989) The chitin content of krill and the annual production of chitin by krill has been reviewed by Nicol and Hosie (Nicol and Hosie 1993) and the chitin composition of whole Antarctic krill was reported to be between 2.4 and 2.7% of their dry weight.
Chitin and chitosan have a wide variety of actual and potential uses ranging from loudspeaker membranes to cholesterol lowering applications (Maezaki et al. 1993; Nicol 1991; Peter 1995; Sandford 1989) so they might become a lucrative by-product of the krill fishing industry in the future. It is unlikely, however, that a krill fishery would be prosecuted solely to produce chitin.
The lipid composition of Antarctic krill has been reviewed by Suzuki (1981). More detailed analyses of lipids have been carried out recently. Antarctic krill caught in winter were analysed for their fatty acid composition by Kolakowska et al. (1994). Polyunsaturated fatty acids (n-3) were found to comprise 19% of the total fatty acids and were stable during processing making krill an attractive nutritional source of these fatty acids. Krill caught in winter had similar levels of fatty acids to those caught in summer but with less variability, probably because of the lack of reproductive activity which can raise the lipid content of mature females to >8% of their wet weight (Kolakowska 1991). Winter-season krill contained 3% wet weight lipids (Kolakowska et al. 1994) and EPA and DHA accounted for about 19% of total fatty acids. They concluded that E. superba, and even the waste products from the current Polish processing technology, is a valuable source of n-3 poly unsaturated fatty acids. The lipids are more stable and contain much higher levels of carotenoid pigments than some fish meals.
Lipids of E. superba change during refrigerated storage (Kolakowska 1988) and the critical factor was found to be the time between capture and freezing and the temperature of freezing. Free fatty acids increase markedly following death and rapid deep freezing is advisable.
The chemical composition of E. pacifica has not been studied as intensively as in E. superba. The fatty acid composition of E. pacifica is similar to that of E. superba. 14:0 and 16:0 are the main saturated acid components and constitute 10 - 20% of the total fatty acids. 16:1 and 18:1 are the main monoenoic acid components and constitute 6% and 15%, respectively. E. pacifica contains higher amounts of EPA (ca. 23%) and DHA (ca.14%) unsaturated fatty acids than E. superba (Yamada 1964).
Lipid composition of the three major North Atlantic species of krill: M. norvegica, T. raschii and T. inermis have been examined in detail (Saether et al. 1986). The fatty acid composition appears to be related to the diet which varies seasonally but these three species contain more depot lipids - triacylglycerol in M. norvegica and wax esters and glycerophospholipids in the two Thysanoessa species - than Antarctic krill.
N. australis from coastal Tasmania has lower lipid levels than higher latitude species (8.5% dry weight vs 15-50%) and this level varies little with season (Virtue et al. 1995). This lower level of total lipid may have advantages when it comes to using this species as an aquaculture feed. In terms of lipid composition, N. australis contains very high levels of long chain w3 poly unsaturated fatty acids which are essential for healthy growth in salmonids and has higher levels of the carotenoid pigment astaxanthin than E. superba. Both these features favour its use as an aquaculture despite its lower protein value (52% dry weight) than traditional salmon feed meals (60-70%).
Antarctic krill (and other species of krill) contain very effective hydrolytic enzymes including proteases, carbohydrases, nucleases and phospholipases. All these enzymes appear to be concentrated in the digestive gland in the cephalothorax of the krill. Because the individual enzymes cohabit, they are mutually protected against the degrading effect of each other. Such a property is rare in nature and thus highly valuable (Anheller et al. 1989). These enzymes have found medical uses in debriding necrotic tissue (Anheller et al. 1989) and as chemonucleolytic agents (Melrose et al. 1995).
Three approaches have been taken to producing an enzymatic debriding intended to treat necrotic wounds (Karlstam et al. 1991). In the first process, whole krill are de-fatted and the proteolytic enzymes are isolated and purified by size-exclusion chromatography. The second process again de-fats the raw krill, homogenises the residue, de-fats the aqueous solution and is precipitated using an organic solvent. This results in an enzyme powder with low specific activity. The third process purifies the enzymes from squeezed autolysed krill. The krill extract can be used directly or after further purification of individual enzymes.
Krill digestive proteinases have also been examined as potential chemonucleolytic agents (Melrose et al. 1995) and proteases from Antarctic krill showed considerable potential. Chemonucleolysis is a therapeutic procedure whereby a degredative agent is injected to reduce the height of vertebral discs and diminish disc pressure on inflamed nerve roots in cases of sciatica.
In another development of the medical application of enzymes from Antarctic krill, Phairson Medical has identified and purified a single enzyme from krill which it refers to as PHM-101, and is moving through the lengthy steps of drug development with this compound. They have identified the molecular mechanism of action of the enzyme. It acts on a wide range of protein cell adhesion molecules and several other clinically relevant molecules. It appears to readily cut CD4, CD8 (CD4, etc. are cell-surface proteins that are involved in cell-cell recognition), ICAM 1 & 2, E & L Selectin and VCAM, all of which are important in inflammation. It also cuts an adhesion molecule on Candida albicans, a fungus that can cause thrush, but it is also a normally passive commensal in many peoples gut, as well as degrading IL-2, bradykinin, and staphylococcus enterotoxin B. This broad specificity may be because of the intrinsic flexibility of the molecule. It is a serine protease with properties common to chymotrypsin, trypsin, collagenase, and elastase. It functions over a wide pH range and is relatively stable up to 55°C. Clinically it has shown a response in the treatment of oral and vaginal candida infections, acne and wound care and may have even broader uses. (R. Franklin, Phairson Medical, pers. comm.7).
7 Phairson Medical Ltd., 602 The Chambers, Chelsea Harbour, London, SW10 0XF, UK.Should a market develop for high value products such as krill enzymes, this may stimulate the krill fishery with the production of food items or aquaculture feed as secondary products.
Obtaining data on the economics of the krill fishery has been difficult but there are a number of sources of economic information which we have cited below which may shed some light on the marketing of several species of krill. The market value of E. superba is difficult to ascertain but whole frozen krill, in 1996 prices, fetch approximately Aus$0.32 kg-1 whereas frozen tail meat is reputed to fetch around Aus$9.50 per kg (figures from industry sources).The value of euphausiids landed in British Columbia varied between Can$0.23 and $ 0.88 kg-1 between 1984 and 1994 and was Can$0.55 - $0.88 kg-1 in 1995. The total landed value of the euphausiid fishery in British Columbia is comparatively small varying between Can$28 000 in 1985 and $415 000 in 1990 (Table 7). The 1995 catch was worth approximately Can$357,000.
The average price of E. pacifica on landing in Japan for 1989-1993 was 2.7 billion yen for the entire area. The average unit price was 45.4 yen kg-1, with lower price of 21-36 yen in the last 2 years, because of the very high catch in 1992 (Kuroda and Kotani 1994a). Availability of Antarctic krill does not seem to affect the price of E. pacifica, as long as the production level of the former species does not change drastically according to Yoshida's, (1995) multiple regression analysis. He showed that the average unit price of E. pacifica (Y in yen per kg) can be predicted by the cumulative catch at the end of March (X1 in 1 000t) and the annual catch of the previous year (X2 in 1 000t) as follows:
Y = -1.15X1 -0.35X2 + 99.41
with a multiple correlation coefficient of 0.89. This means that the increase in X1 by 10 000t reduces price by 11.5 yen, and the same increase in X2 reduces price by 3.5 yen. There is a good agreement between the real average price and the calculated value in 1987-1994 (Fig. 32).
No published economic analysis on the Antarctic krill fishery has been attempted since the review in (Budzinski et al. 1985). The low level of fishing for Antarctic krill in the last 5 years has been attributed to the high costs and low returns.
A recent review examined the requirements for fish meal and sources of protein needed for the aquaculture industry (Rumsey 1993). In 1993 12% of the world's fishmeal was used for aquaculture feeds and a projection to the year 2000 saw the requirement rise to 10-25% of fishmeal production. World fish meals production had only increased 27% between 1970 and 1990 and was projected to decline by 5% between 1990 and 2000. Rumsey noted that "Until suitable alternative sources of protein are found or other animal feeds begin to rely less on fish meal, the cost of raising fish can be expected to increase significantly". He suggested the use of vegetable sourced protein feeds and of single celled proteins and by-product animal proteins as potential alternatives to fish meal but pointed out that each of these has significant problems when used as a dietary source for aquaculture. He also alluded to the problems associated with using fish meal as a source of food for farmed fish and suggested that there would be a move away from fishmeal in the aquaculture industry.
It is likely that as aquaculture prices rise and as more innovative technologies are applied to krill to develop a range of products for the aquaculture market there will be a rise in demand for krill. Krill, of all species, appear to have a number of features that make them an attractive source material for the aquaculture feed industry and as these features become more evident, the demand for krill will grow.
Krill products for human consumption will continue to be produced but are unlikely to be the driving force behind the fishery in the near future. In parallel with the development of krill products for aquaculture and human consumption will be an increasing demand for krill products for non-nutritional uses such as for pharmaceuticals and for industrial uses. These demands may develop to the point where they become the major economic justification for krill fishing or at least will be instrumental in putting the fishery on a sound economic basis.