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Dimitri
Sclabos Katevas

On the subject of Krill: research by Dimitri Sclabos with Dr. V. A. Bibik & Dr. A. S. Vinnov

Much has been said about South Antarctic Krill (Euphausia superba, Dana) species ...

	William Martin Christensen

	William Martin Christensen was born in Farnborough, England in 1962, where he received his primary and secondary education. He then went on to study Industrial Engineering at the National University of Buenos Aires (UBA). He worked as assistant to the engineering department of Machinefabriek Amersfoort b.v in Holland, working mainly in heavy hydraulic machinery and machining of large tailor-made engineering pieces. Cristensen later worked in Beck Kartonnage ApS Denmark learning fish handling an fish block production at several plants in Bornholm Denmark including Espersen. In 1989 he founded the company Christensen s.r.l. The company's main activity was at that time, representing Scandinavian engineering firms providing machinery and supplies for fish processing industry on board and on shore. In 1992 company was awarded by H.R.H Prince Henrik of Denmark with the "Dansk Arbejde".

Situation of the Illex Squid Fishery in the South Atlantic
Tuesday, July 20, 2010

Basic introduction to the Illex Argentinus:

This fishery is a very important one, not only on economic terms but also for its role on the ecosystem as squid is feed-bait for many species, from cetaceans to hake just to name some.

Squid had its historical season starting in January-February fading out July-August and on extraordinary years good catches were observed even up to late September.

This cephalopod, lives about a year, reason why its TAC is a high percentage of estimated biomass.

One may consider The Falklands Current, is its carrier, as a massive conveyor furnishing plankton for their early stages of life.

The fishery:

The squid fishery is mainly performed by jigging vessels that freeze the catch onboard by means of blast freezers. There are also factory trawlers that spot fish it (one fishing trip a year). Jigger vessels fish by night, using powerful lights to concentrate the fish school under the vessel´s hull and then by means of hauling in the special barbless hooks on which the squid are caught. The tools to locate the fish schools are mainly two, a) Sea surface temperature (SST) fax charts b) Echo-sounder. The fishing master selects a fishing spot based on it SST and its historical experience which could be also strengthen by radio calls with colleagues.

Today we have more sophisticated and precise tools as satellite and radar generated charts, which are gaining a position in the market.

During the last years, we have observed, certain irregularities on catch rates considering that it’s an Olympic fishery system:

Year	Catch in tonnes Argentine EEZ
2004	65,000
2005	123,800
2006	261,000
2007	204,000
2008	230,000
2009	55,000
2010	26,000

The interesting issue on this is that many players in the fishery were quite cautious or skeptic on the 2010 season based on the results of 2009. This year 2010, February was quite promising as the catch was of about 16.000 tons, and then it dropped down to just a couple thousands a month. Up to recent days, the season was considered a complete failure having not more than 4% of the fleet left fishing. Now they found an abundant stock about 42° south. This event is a proof that the season was not a complete failure, or better says that the squid is not yet depleted. Colloquially the fish went another way than the historical!

This is nothing but a solid proof that the environmental, mainly oceanographic conditions are changing significantly, and influencing on the migrating pattern of the specie. Personally I have been collecting oceanographic data since 2004 of the south Atlantic and overlaying it with the catch rates on different species. I observed surface sea temperature increased in some areas up to 1.8° Celsius in an inter-annual basis, but more that this is the SST isotherms pattern changes which surprises me. We must consider that changes of 0.5 °C are significant enough for temperature sensible fish (stenothermals) to dislike those waters. It is quite remarkable to observe the changes on plankton concentration and distribution also in an inter-annual basis. Plankton concentration on surface and subsurface waters is a result of up-welling currents. There is an event of these up-wellings starting on Spring (late September-Early October) which lasts until the end of Summer (late March-early April).

During the last two years these plankton concentration levels have risen substantially and persisted in time. Normally you could see plankton concentration declining in winter, we are presently in winter time having plankton concentrations and distributions that would very much look like summer time ones. Plankton is not only the first link on the atrophic chain, but also a refuge for bait fish from its predators. High plankton concentrations, are bad for squid jigging techniques as the plankton disperses the light, just alike headlights of a car while driving on a foggy road. Turbid waters make it very hard to predators to see their prays. This is also the reason why demersal catches have been erratic and when achieved the performance of trawlers was very good indeed. Other behavior change observed was that of demersal predators where having a semi pelagic swimming avoiding bottom trawlers to catch them. This is due the lower illumination found on deeper waters due the high plankton concentration. Simultaneously we can observe that geostrophic and total sub-surface currents are changing their pattern and intensity. A good example of this is the present shaping of confluence of the Falklands current and the Brazil current both of the same date but corresponding to 2007 and 2010 (good and bad year in terms of fishing).

(The charts attached were produced by Geoye Inchrough it Fisheries Information Service as viewed by the software OrbMap7.)

The purpose of this article is nothing but to create awareness that we are experiencing changes which we should take seriously into consideration when we take decisions. Events like El Niño, La Niña and now the Modoki Niño, are becoming more frequent and intense each year. We should understand that the old way of decision making on fishing is getting more and more inefficient, as fish habitat is not the same and fish behavior is ruled on natural stimulus as temperature, feed, light, current, predators, just to name some. There is no linear correlation on single events observed and catch rates but yes we can see a clear strong trend linking both when we consider 3 or 4 oceanographic variables simultaneously.