FREDERICTON — Canada's fisheries minister is shrugging off accusations that a proposed cull of 140,000 Atlantic grey seals is being driven by politics, not science, saying "seals aren't vegetarians or vegans -- they eat fish."

Keith Ashfield responded Tuesday to four marine biologists at Dalhousie University in Halifax who say the five-year plan submitted for his approval is aimed only at appeasing fishermen as they struggle with dwindling cod stocks.

The scientists wrote an open letter to the minister in September, saying the proposal can't be justified by existing scientific evidence. They said the proposal, drafted by a group of federal scientists and industry representatives, was biased because it focused only on the negative impact of grey seals.

The minister, in Fredericton for a funding announcement, said Tuesday the proposal is based on rigorous scientific research that concludes hungry grey seals are the most likely reason why cod stocks are not recovering in the southern Gulf of St. Lawrence.

"The information we received, based on science through a committee report, was that on the grey seal issue that they are having an impact on the cod stocks," Ashfield told reporters.

"They have suggested up to 70,000 seals per year should be removed from the herd. It has grown exponentially."

There are between 330,000 and 410,000 grey seals living off the Atlantic coast -- a 30-fold increase since the 1960s, the Fisheries Department says.

"When you look at it, seals aren't vegetarians or vegans -- they eat fish," Ashfield said. "They do have an impact."

Still, Ashfield has asked a Senate committee to take a closer look at the issue, an official for Newfoundland and Labrador Senator Fabian Manning said Tuesday. It is expected to report its findings next May.

In March, the Canadian Science Advisory Secretariat -- a branch of the Fisheries Department -- called for a five-year experimental cull that would eliminate 70 per cent of the grey seals in the southern Gulf of St. Lawrence.

The cull could start with the killing of 73,000 seals in the first year alone, the secretariat said.

The Fisheries Resource Conservation Council, which includes scientists and fishing industry representatives, followed up with a report in September that endorsed the idea, saying a total of 140,000 seals should be killed over five years.

The biologists at Dalhousie were also critical of the council's report.

"Contrary to the pleadings in the FRCC report, the implementation of a grey seal cull represents the antithesis of a precautionary management approach," they said in their letter.

"It is well documented in the scientific literature ... that a cull could produce a number of unintended consequences. Scientists cannot rule out the possibility, for example, that a grey seal cull could have deleterious consequences for recovering fish stocks, including cod."

There are an estimated 104,000 grey seals that forage in the southern Gulf, including 36,000 from Sable Island, 5,000 from Nova Scotia's eastern shore and 63,000 resident seals.

Cod stocks off the East Coast collapsed in the early 1990s after decades of overfishing. The population is slowly recovering in some areas, but the cod could disappear from other areas, including the southern Gulf, scientists say.