TOKYO, July 16, 2008 (AFP) - Supplies at the world's biggest fish market, in Tokyo, dropped by a quarter Wednesday after a one-day strike by Japan's fishermen to protest against soaring fuel costs.

The volume of fish sold on the Tsukiji Fish Market fell 24 percent from the previous day to 401 tonnes. Morning auctions lasted only five minutes, compared with up to 30 minutes on usual days, market officials said.

The decline came after some 200,000 boats -- almost the country's entire fishing fleet -- cancelled the day's work on Tuesday to raise awareness of the industry's plight.

Thousands of fishermen also rallied in a park to demand emergency help, warning that soaring oil prices could cripple the key industry in the nation, which is famed for sushi.

'Despite the fall in supplies, prices were stable today' as wholesalers had stocked extra fish on expectations of the supply shortage, a market official said.

But market participants said prices of some fish such as tuna and squid are expected to rise soon as the impact of the strike would be felt gradually.

Oil prices have doubled over the past year and are up five-fold since 2003, hitting record highs above 147 dollars a barrel last week.

Thousands of fishing boats are already sitting idle at port because fishermen cannot afford fuel.

'I understand people in the fishing industry are suffering a lot,' Prime Minister Yasuo Fukuda told reporters late Tuesday.

'As the government, we want to take various measures,' Fukuda said, adding that his cabinet plans to unveil its support by the end of July.

The government has already announced measures to help small firms, fishermen and farmers cope with high oil prices, easing conditions for state-backed loans and stepping up aid to foster better fuel efficiency.