September 23

Satellite tracking can help increase fish catch

By M.Raghuram
[SEPTEMBER 23, 2002]

MANGALORE SEPT. 22 . Fish catch in Dakshina Kannada District is coming down each year. Though the average fish catch in the past 10 years was 70,000 tonnes, it has been only 49,000 tonnes in the past two years.

Depletion of fish progeny and inability to track fish movement at depths below 45 metres to 60 metres have been cited as reasons for the low fish catch.

The rudimentary marine and terrestrial fish-tracking instruments are on the way out, and satellite tracking and forecasting systems are being used in the region. The Department of Fisheries is gearing up to utilise them for the improvement in the performance of the fisheries sector in the State. The State, which has a coastline of 300 km. with a continental shelf area of 27,000 km. and an Exclusive Economic Zone (EEZ) of 87,000 km. supporting the rich "pelagic" and "demersal" fisheries, has a resource potential of 4.25 lakh tonnes of fish per annum. Karnataka is on the world route map of the yellow-finned tuna, which migrates from the mid-Mediterranean towards the Rann of Kutch off the Gujarat Coastline. Because of lack of remote-sensing facility, the fishermen in the State are not able to intercept the movement of this variety of fish.

According to the recommendations of the national-level workshop on "Satellite-based potential fishing zone forecasting for Karnataka", nearly 45 per cent of Europe is supplied with yellow-finned tuna, as these fish, measuring four ft. to six ft. in length, move in shoals as large as a cruise ship. In 2001, the Western European Fishermen’s Association reported that their boats caught a shoal of yellow-finned tuna in the southern Mediterranean, which was 4.5 km. long. Due to overcrowding of their hold, they had to abandon fishing on the spot.

While fishermen depend on traditional knowledge for inland fisheries, deep-sea fisheries need the help of satellite images. Water colour, turbidity, wave size and direction, wind patterns, state of the sea, and climatic factors are considered helpful in locating the likely availability of fish in a region.

Traditional knowledge has a bearing on fishing strategies. Taking a cue from this, techniques have been developed to use satellite-based remote-sensing to identify potential fishing areas.

Though direct spotting of fish shoals is not possible from remote-sensing satellites, certain oceanographic features, which control and identify fish stock, can be identified.

"Sea surface temperature" (SST) and "ocean colour" are the key oceanographic parameters that control the distribution of fish resources. Taking this into consideration, the Union Department of Space has launched a state-of-the-art satellite for ocean applications.

The Oceansat-1 has two major sensors, one of which is the ocean colour monitor (OCM) for deriving ocean colour information. With the availability of data, the Space Applications Centre at Ahmedabad is making efforts to provide potential fishing zone foretaste by integrating SST derived from NOAA-AVHRR with that of the ocean colour information derived from Oceansat.

Integration of these parameters will go a long way in the identification of likely availability "pelagic" varieties of fish. This forecast may also be valid in many cases to "demersal" varieties when the conditions are found to be uniform.

At present, "Integrated Fishery Forecast" (IFF) is being carried out in Gujarat and Kerala. The Space Applications Centre has come forward to give a similar forecast for the State’s coast from this season at the instance of the Indian National Centre for Ocean Information Services (INCOIS), which is a nodal agency under the Department of Ocean Development. If the recommendations are implemented, fisheries in the State will grow by leaps and bounds, and this will open up several issues such as formation of giant fishing cooperatives with capabilities of taking up mechanised deep-sea fishing on lines with the "bull trawlers" of the U.K., the U.S., and Sweden, and also onboard connectivity to improve communication and fish tracking.