What will the future be like on Earth? Will there be enough food for the world’s ever-increasing population? Even today’s society cannot supply the world’s population with an adequate amount of food, so what will happen when the Earth doubles in population? The Earth will need to find a new and relatively large future food resource. One such possibility is the Antarctic krill.

The Antarctic krill, or Euphausia Superba, is a small pelagic crustacean found in huge swarms in the Antarctic. These swarms may hold up to 20,000 individuals per cubic meter (Dethleffsen, 1999), attain densities of ten to sixteen kilograms per cubic meter (FAO Fisheries, 1974), and average six hundred square feet by a dozen feet thick (Stevens, 1995). Adults may attain a maximum length of seventy millimeters with most averaging forty-five to fifty millimeters. Unlike other Euphausiid species, Euphausia Superba feeds almost exclusively upon phytoplankton (FAO Fisheries, 1974). This contributes to the very high abundance and potential catch of krill, since there are comparatively small losses between the primary production and the potential harvest by man (FAO Fisheries, 1974). Paired with a biomass of 1.35 billion tons, about five times the weight of all five billion plus humans (Stevens, 1995), and containing a good source of protein, the Antarctic krill seems to be a perfect solution to the Earth’s increasing desire for food. By harvesting the Antarctic krill, its location, value, new and traditional methods of recovery, cost, and the krill’s sustainability as a resource are all important factors to consider.

As afore mentioned, the Antarctic krill is located throughout the Antarctic in the region between the Antarctic convergence (50-60 degrees South) and the continent. They are found mainly in the upper water layers down to 250 meters and often occur in swarms at or near the surface (FAO Fisheries, 1974). Apart from summer, Euphausia Superba spends most of its life in waters of a temperature of zero degrees Celsius, below or at the edge of the pack ice (FAO Fisheries, 1974). During the summer, though, it is most abundant in the high latitude coastal current in the East Wind zone and in the low latitude oceanic current from the Weddell Sea, and also in the regions of the Bransfield Strait and South Georgia (FAO Fisheries, 1974).

Due to this fact and the harsh winter environment, it is assumed that the Antarctic fishing season for krill will last five months, from mid-November to mid-April (Eddie, 1977). Generally during the fishing season, "it seems that the krill are most likely to be found in areas where there is turbulence or upwelling, or on the downstream side where currents flow round islands, but the distribution within such areas is patchy. The mobility and swimming speeds of krill cannot be very high so they may remain within a distinguishable water mass or a general area for long periods. However, no useful method of location has been developed or proposed that depends upon oceanographic phenomena. What may be of more direct usefulness to the fisherman as an indication of the likely presence of high concentrations of krill in the near vicinity, is the existence of breeding colonies of seals or birds on nearby coasts (Eddie, 1977)." The same source also points out that the presence of whales should indicate good concentrations of krill.

The value of krill is in the hundreds of dollars per ton. However, it is difficult to predict the effects that declining catches, advancing technology, and international political activities will have on this value. Conversely, consideration must be given to the effect that the introduction of millions of tons of krill would have on its own value and on the value of other protein sources (Eddie, 1977)." Price assumptions for various krill products are as follows:

krill meal : $340 per ton

attrition-peeled tail meat : $2,000 per ton

roller-peeled tail meat (mince or coagulate) : $600 per ton (Eddie, 1977).

It is also assumed that it takes five tons of krill to produce one ton of krill meal, another five to produce one ton of attrition-peeled tail meats, and yet another five tons of krill to yield two tons of minces and coagulates.

Because of the many assumptions and doubts that are involved with the profitable exploitation of Euphausia Superba, discussion of whether a proposed system may or may not be profitable has been confined to stating the gross earnings attained recently in certain other fisheries by vessels of comparable size and type. The general relationship that may exist between total annual operating costs to the costs of replacement and the adjustment needed for the conditions in the Antarctic are also included (Eddie, 1977). An example of one such proposed system is the independent super trawler. A trawler of 115.5 m LOA might have a useful hold capacity of 4,500 cubic meters. The vessel might carry 2,750 tons of frozen peeled tail meats, representing perhaps 14,000 tons of caught krill. The daily average rate of catch of krill acceptable for processing might be just over ninety tons per day and the vessel would have an adequate fuel tank capacity. This vessel might earn 5.5 million dollars during a 150-day season (Eddie, 1977).

During the early trials of capturing the Antarctic krill, methods of capture were based on the assumptions that krill swarms were found mostly at the surface and that krill are capable of avoiding an oncoming net or ship (Eddie, 1977). The purse seine and side-towed, surface-skimming frame trawls were two of the methods deployed under these assumptions.

The purse seine is used to surround an area in or near the surface with a ring netting which is then closed ("pursed") to prevent downward escape of the intended catch. Both single-boat and two-boat purse seines were deployed in the catching of krill. Due to the fact that purse seining is unable to capture swarms below depths of one hundred meters, it is essentially a good weather operation, and that little selectivity can be used, the method of purse seining has been abandoned by krill fisherman (Eddie, 1977).

The side-towed, surface-skimming frame trawl was extensively tried during the early trials of capturing krill. Because the passage of a ship tended to divide the swarms of krill, two solutions were tried in order to improve the efficiency of the trawl. One was to tow a trawl on the surface, with the ship always moving in a curved path so that the trawl was not being towed behind the ship (Eddie, 1977). The other was to suspend the trawl directly from the side of the vessel. The mouth opening was defined by a rigid metal frame suspended from a derrick, to which the net proper was in turn attached. The limitation of these devices is that its size is severely restricted by practical considerations of handling in bad weather (mouth openings of only five meters by five meters) and that it can only operate in the surface layer (Eddie, 1977). Due to these limitations, these types of trawls have also been abandoned by krill fisherman.

"By the mid-1970’s, two facts had been realized. One was that krill swarms could be found more frequently well below the surface than at or near the surface, and down to a depth of several hundred meters. The second fact is that krill are capable of little or no effective action to avoid oncoming nets of dimensions commonly used in full-scale trawl fishing operations (Eddie, 1977)." These new facts encouraged krill fisherman to use a larger mouth opening with a smaller mesh size at a mid-water depth. Even though the trawl would be moving considerably slower, the larger mouth opening and the krill’s inability to escape the oncoming net would provide an increase in krill catch rates. Thus, the single-boat aimed mid-water trawl is the standard type of gear employed for the capture of Antarctic krill (Eddie, 1977).

For the future, a couple of new possibilities could be pursued in the catching of Antarctic krill. First, while fishing a mid-water trawl, the trawl has to be hauled and shot so frequently that the loss of time has a very marked effect on krill catch rates. "If very high daily catch rates are desired, consideration should be given to means whereby a trawl can be kept in the water for a higher proportion of the time (Eddie, 1977)." Secondly, larger mouth openings on mid-water trawls may be desired for catching larger quantities of krill. "The reason for the small size of krill trawls is the high drag caused by the need to use very small meshes so that, for instance, the 400 square meter German trawl absorbed about the full power that could be developed at trawling speeds by FMS WESER, a vessel with a maximum shaft horsepower of three thousand (Eddie, 1977)." By creating, a vessel with a larger shaft horsepower, an engine with a large-diameter, slow-turning propeller of large blade area, and a net of stronger, yet smaller diameter twine (Eddie, 1977), nets with larger mouth openings may be towed and greater catch rates may be achieved. Lastly, "further investigation of the attraction of krill by light is desirable (Eddie, 1977)." If precise conditions can be established in which krill can be attracted with reasonable certainty, a more continuous flow of raw material in an undamaged and more lively condition may also be established (Eddie, 1977).

Some of the main items which would have to be examined in any serious attempt to predict the costs of operation of a stern freezer trawler in the Antarctic krill fishery, are costs of construction of vessels, capital associated costs, license and harbor fees, fuel, gear, and manpower (Eddie, 1977). These costs are based on the costs of vessels in other fisheries, but different cost items will vary in different ways and need to be adjusted to the very different conditions of the Antarctic. Cost items such as marine insurance, fuel, crew costs, and maintenance will vary greatly for different sizes and types of vessels. Finally, the total annual operating costs will average fifty to sixty percent of the replacement cost of the vessel according to a pilot study on the costs of fishing vessels completed for FAO in 1976 (Eddie, 1977).

As noted earlier, the principles of finding krill below the surface and that they cannot escape oncoming nets was realized and applied during the mid 1970’ by Japanese, Chilean, West German, Russian, and Polish expeditions (Eddie, 1977). This resulted in the use of the single boat aimed mid-water trawl. "As a result, the estimates of catch rates that might be enjoyed on the full scale have risen in the last five years from something less than 1 ton per hour average to something in the range of 5 to 20 tons per hour average (Eddie, 1977).

There are many different views as to the sustainability of the Antarctic krill as a resource. Estimates of the potential yield of krill by Russia and Japan are within the range of 100-200 million tons (FAO Fisheries, 1974). These estimates were made in the early 1970’s, when scientists believed that krill only lived to the age of two years. "After research published in 1987 showed that krill could live in captivity for 9 to 11 years, most researchers now believe that, if they escape their hordes of predators, krill can live for at least five years in the wild (Stevens, 1995)." "If Antarctic krill live two years, he explains, then stocks that have been estimated at 55 million to 7,000 million tons are the result of two years' production. However, if krill live to be ten years old, then the annual production is one-fifth as much, and the annual harvest limits must be reduced (Stevens, 1995)." Although the annual catch limit on krill is 1.5 million metric tons for the South Atlantic Region, the annual krill catch has never amounted to more than about 550,000 tons and yet it is the largest crustacean fishery in the world.

The technology of krill harvesting and utilization has advanced considerably throughout the years. As more and more countries engage in the commercial exploitation of krill, the technology can be expected to develop even more rapidly (Grantham, 1977).

"Present indications are that krill products are moving towards the mass market outlets necessary for any significant exploitation of the resource. Although areas can be identified where further information is needed, it is believed that commercial pressures and incentives will stimulate the necessary development work. No single product will predominate in the krill market, and as yet it is not possible to identify the likely product spectra. The process technology will be advanced, the products generally sophisticated and costly, and the investment requirements high. Thus the utilization of the resource will tend to be limited initially to a few of the developed countries. Coordination and probably assistance will be necessary if the utilization is to be extended to the benefit of other nations (Grantham, 1977)."

At this present time, though, the Antarctic krill is formidable resource, providing an average of 300,000 tons per year (Stevens, 1995). Will the Antarctic krill be the total solution to the world’s increasing desire for a food resource? Most likely not, but with the advent of new technology and research, only time will tell.

Eddie, G. O. The Southern Ocean: The Harvesting of Krill. Rome: United Nations Development Programme, 1977.

Grantham, G. J. The Southern Ocean: The Utilizations of Krill. Rome: United Nations Development Programme, 1977.

Informal Consultation on Antarctic Krill. FAO Fisheries Report No. 153. Rome: Food and Agricultural Organization of the United Nations, 1974.

Stevens, Jane E. "Dismantling the Myths of the Southern Ocean: The Secret Lives of Krill." Sea Frontiers 20 (1995): 26.

Antarctic Krill. 9 October, 1999. Dethleffsen, H. G. 23 October, 2000. <http://www.ecoscope.com/krill4u.htm>

Time to Krill? 30 Oct. 2000. Nicol, Stephen. 2 Nov. 2000. <http://www. antdiv.gov.au/science/bio/issues_krill/issues_krill.html>.

 

 

Illustration 1

Krill Catch Rates in the Southern Ocean

(Nicol, 2000)

 

 

 

 

Illustration 2

The Line Graph Represents Krill Catch in Thousands of Tons

The Pie Graph Represents Catches of Krill by Nation and Area

(Nicol, 2000)

Illustration II

The Line Graph Represents Krill Catch in Thousands of Tons

The Pie Graph Represents Catches of Krill by Nation and Area

(Nicol, 2000)