"We have learnt that more than 100 fishermen who were on board around 18 fishing boats were apprehended by PMSA near the international maritime boundary line off Jakhau coast yesterday," National Fishworkers' Forum (NFF) secretary Manish Lodhari said.
"The fishermen who escaped have informed us about this," he said.
The NFF is trying to establish contact with the Pakistani agencies to get the exact number of those kidnapped by PMSA, he said.
The PMSA had earlier this month also detained 115 fishermen and seized 19 boats.
"The 100 men would be taken to the court on Monday," senior police official Adeel Chandio said after the fishermen were handed over to the police by MSA officials.
India and Pakistan routinely arrest fishermen on charges of entering each other's waters.
"In March so far, the PMSA has separately held over 225 fishermen along with nearly three dozen boats," Mr Lodhari said.
The development comes after the Indian Coast Guard captured nine Pakistani nationals along with a fishing boat off Jakhau coast in Kutch on Friday.
Last month, the BSF had detained four abandoned Pakistani fishing boats near Sir Creek in Kutch district during an extensive search operation in the area.
Pakistan released 219 Indian fishermen as a "goodwill" gesture in January.