He had earlier been charged with illegally fishing in British territorial waters and refusing to comply with orders from a fisheries protection officer.
Magistrates ordered Michel Mesnage, skipper of the Cherbourg-based trawler La Calypso, not to leave the island until his case was heard tomorrow. The boat itself has been detained. Representatives from the French Fisherman's Association signed his bail surety of 20,000 French francs ( pounds 2,400).
There are fears that his enforced detention on Guernsey may prompt other Normandy trawlermen to take retaliatory action. One trawlerman, Christian Le Blanc, warned before the hearing that if any action was taken against Mr Mesnage, French fishermen would sail to Guernsey to rescue him.
'We will mobilise ourselves,' he said. 'At the moment, what the action will be I could not say. We will decide together. But one thing is for sure. If our colleague is put in prison, we the French will want to go to get him.'
Following Mr Mesnage's arrest, Jean Le Boucher, president of the Normandy Regional Fishing Committee, warned British crews to stay away from France. 'After what happened it would be better if there weren't any (British boats). We'd avoid clashes that way,' he said.
John Dodd, chairman of Guernsey Fisherman's Trading Company, confirmed that a trawler due to land in France had changed course back to the Channel Islands yesterday morning.
Mr Mesnage was detained on Friday when five naval officers from the fisheries protection vessel HMS Jersey boarded La Calypso and diverted it to St Peter Port, Guernsey.
The French trawlermen are demanding the right to fish within a six-mile exclusion zone around the island which they say they have always worked.
Last Sunday, officers from HMS Brocklesby boarded La Calypso because it was suspected of fishing within the limit. Mr Mesnage allegedly refused to dock in St Peter Port and took three officers to Cherbourg. They were later returned unharmed to the Brocklesby.
Twelve marines, trained in unarmed combat, arrived yesterday aboard HMS Orkney and HMS Jersey to assist the two fisheries protection vessels enforce fishing zones around the Channel Islands, doubling the size of their boarding parties from three to six.
'We think the presence of the Royal Marines will have a deterrent effect. We regard it as a prudent precaution in view of recent events,' a Ministry of Defence spokesman said. 'The Royal Marines are known to be well- trained, rather tough troops, and they might discourage fishermen of any nationality from reacting in a way that was inappropriate.'
French fishermen said that Mr Mesnage's arrest could jeopardise a four-week truce agreed between British and French fishermen while their governments negotiated a political solution.
Last weekend French fishermen, enraged by British efforts to enforce fishing limits around the Channel Islands, boarded a Royal Navy vessel making a goodwill visit to Cherbourg and burnt its white ensign flag.