The random security check by Coast Guards had revealed that several fishing vessels were operating under a single name and licence, said the Akhil Maharashtra Machhimar Kriti Samiti.
"The finding proves that Mumbai's coastal security can be easily breached by terrorists," Samiti president Damodar Tandel said.
The fishermen's body also claimed that Indian security establishment has yet to learn any lesson from the 26/11 episode, where terrorists had taken a sea-route to reach the shores of Mumbai to launch the attacks.
At a meeting at the Coast Guard office last month, the Coast Guard confirmed conducting random check of coastal security and finding that four to five fishing vessels were operating under a single name, with same license number and even with same colour of the boat, Tandel said.
Representatives of fishing societies and officers of the Navy, Customs, Mumbai police and ONGC attended the meet, he said.
"This means, of the 159 licensed purse-seines net fishing vessels, there are 700-800 vessels operating illegally by using the same name, number and colour of the boat," Tandel said.
"Mumbai's coastal security can easily be breached as terror outfits can gain easy access to any of these 700-800 illegal boats which are off the radar and nowhere reflected in government and police records," Tandel said.
He said the purse-seine net fishing vessels were banned by the Centre.
"Union Ministry of Agriculture had instructed state governments not to allow this type of fishing activity which poses danger to marine ecology," Tandel said.
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