The Taoiseach has told the Dáil that exploitation of undocumented workers in fisheries "must be stamped out".

Micheál Martin said that the fishing industry is "going through a traumatic period" and "this is something that it can't afford to allow happen".

"There can certainly be no place for exploitation of workers in the fishing industry", he said.

He was speaking after an Oireachtas Committee heard that successive governments have allowed "horrific conditions" to continue in the sector.

There has been "criminal failure by the State to stand up for these the rights of undocumented workers", Paul Murphy, Solidarity-PBP TD said.

He referenced a report from Maynooth University, published this week, which found that two thirds of undocumented fishers work up to 20 hours a day.

The same proportion feel unsafe, he said, and over half have been subjected to racial abuse.

The Joint Committee on Enterprise, Trade and Employment was examining how effectively the Workplace Relations Commission protects migrant workers.

Specifically, it examined the scheme - currently under review - where permits given to fishers are tied to a single employer, which is a "recipe for abuse".

Michael O'Brien, head of the Fisheries Campaign with the International Transport Workers Federation, said the scheme is used on the largest 180 vessels in the entire fishing fleet.

"A high proportion" of these vessel owners are breaking the terms of the scheme, he said.

He recounted the "acute risk" these fishers face, often resulting in "back injuries, loss of digits... and premature aging".

He told the committee that fishers in their 40s "look like old men".

Sector-wide permits are urgently needed, he added.

Mr O'Brien warned that there is "a core of rogue employers" who are acting with impunity.

The Taoiseach also told the Dáil that he will talk to the Transport Minister and industry representatives on how to address the permit issue.

Undocumented fishers cannot take a case to the WRC, but the commission can investigate a case if asked by the Minister for Justice.

However, in the past seven years, only two cases have been referred by the minister, Liam Kelly, the Director General of the Workplace Relations Commission said.

Just one of those cases was acted on, he added.

The last Parliamentary Question which was raised on this issue revealed that there are currently 230 fishers registered in the scheme.

However, Mr O'Brien said it is impossible to know the exact number.

"Hundreds, I would say, is the best answer I can give", he told the committee.

Sinn Féin TD Louise O'Reilly said the scheme was "essentially a pipeline of cheap labour".

The committee also heard that the sector is one of those where human trafficking is carried out.

"To date, 35 fishers have been admitted to the National Referral Mechanism for human trafficking", Mr O'Brien said.

He pointed out that Ireland has been downgraded by the US State Department to it's Tier 2 Watch list for action on trafficking.

Azerbijan, Belarus and Romania are the three other European countries in that category, he added.

Mr O'Brien emphasised that the current review is "last chance saloon", adding that "this scheme has to be got right"

The Workplace Relations Commission conducted 20 prosecutions arising from inspections, Mr Kelly said.

However, he admitted that it does not notify the Department of Justice, which administers the scheme, and can decide to withhold a permit from an employer.

"It's something we should look at", the WRC chief conceded, particularly in the case of repeat offenders.

Mr O'Brien said that the low number and nature of convictions secured by the WRC are "simply not dissuasive".

"Not a single vessel owner has been banned", he pointed out.

Employers face District Court fines of just €500 on catches which can be worth €25,000, he said.

Mr O'Brien believes that boat owners need to be taken to the Circuit Court to face "four figure fines" and prison terms.

In the Dáil, Micheál Martin agreed that there have been "too many incidents...where clearly the rights of workers were not upheld, or even basic documentation couldn't be provided".

Fine Gael Deputy David Stanton expressed concern that the sector was being negatively "painted with a wide brush".

He said that he was contacted by employers who are angry at the behaviour of those who are breaking the rules, suggesting that they be "named and shamed".

Mr Kelly said those convicted are only named in the WRC annual report, but would consider issuing press releases in future.

Paul Gavan, Sinn Féin Senator, noted that despite the WRC having secured increased funding, the number of inspectors in this area has fallen from 16 to seven.