A moratorium on the taking of river herring, instituted three years ago because of dwindling stocks, appears set to be extended for another three years.
A decision will not be announced until next Friday, but a public hearing attended by Vineyard fishermen last week made it clear the fishery was still far from recovered.
Paul Diodati, the director of the Massachusetts Division of Marine Fisheries, said there had been some improvement in stocks, but populations were still low.
The meeting heard data indicating the severity of the problem, gathered over 30 years. Herring populations have fluctuated over fairly regular five-year cycles. But from 2002, the cycle stopped and numbers dropped alarmingly. They now are stabilized.
As well as numbers, there was concern about the age and size of the population, which has declined over decades.
Where there had once been large numbers of larger fish, six, seven or eight years old, the oldest being seen now were just four or five. An extension of the moratorium would mean the population had been protected for a whole herring life cycle.
But the cause of the sudden decline remains uncertain.
Certainly, said Mr. Diodati, speaking to the Gazette after the meeting, overfishing was part of it. He noted that before the moratorium, recreational fishermen were permitted to harvest them directly from runs as they made their way from the sea to fresh water to spawn.
But there could be other factors too, including poor water quality, obstructed passages to spawning areas and predation by seals, dogfish, cormorants and striped bass, all of whose populations are increasing.
The suggestion that striped bass could be involved is ironic, given that favorite sport and food fish itself had to be rescued from population collapse through rigorous management of the stocks. But the evidence shows that when bass numbers go up, so does their predation of herring.
Mr. Diodati said the illegal taking of herring by fishermen seeking bait for striped bass remains a serious concern.
At last week’s meeting, though, most of the comment from the couple of dozen recreational and commercial fishermen present concentrated on another possible cause for the depletion of herring stocks — bycatch by large offshore vessels.
They were strongly critical of the mid-water trawl fishery, and focused on stories of individual bycatches — incidental landings of herring by vessels after other species — of up to 70,000 pounds.
Nor were they pacified by assurances that official monitoring of bycatch showed it to be negligible, a fraction of a per cent of overall catches.
The repeated suggestion was that the monitoring was insufficient and that bycatches are being dumped and/or unreported.
Cormorants were the other target of most criticism.
Vineyard Haven shellfish constable Derek Cimeno said he had seen 100 cormorants at the Lagoon Pond run. Capt. Buddy Vanderhoop of Aquinnah estimated 5,000 of the birds on Noman’s Land.
It is illegal to cull them.
Generally, though, those present at the forum appeared resigned to a further closure, which is widely seen as the likely judgment after next Thursday’s meeting of the Marine Fisheries Advisory Committee.
Also likely are new limits on the taking of blue crabs. A proposal by Edgartown recreational fishermen would see a catch limit of 50 per day.
The proposal stemmed from opposition to the actions of a couple of Island fishermen who netted large numbers of blue crabs for bait.
The meeting heard complaints from several of those present that the large catch in the Edgartown Great Pond last summer had caused a subsequent collapse in the blue crab population this year.
Tom Turner, one of those who netted the crabs, argued the blue crab population is highly variable anyway, and said there was no proof of damage to the resource.
The argument went back and forth, largely unsupported by scientific evidence, for not a lot exists on blue crab populations, which have not previously been taken for anything other than recreational purposes on the Vineyard.
But later, Mr. Diodati indicated some limits were now likely on how many could be taken.
“It’s clear from talking with our expert on crustaceans, that we don’t believe blue crabs could sustain very large fishing effort,” he said.
He noted also that the Vineyard lies near the northern limit of blue crabs, and that such outlier populations are particularly sensitive.
He said the DMF will continue to examine population levels of the crabs.
But Mr. Diodati said they would not address one complaint from several of those at the forum, that the crabs were harvested not for human consumption, but to be used as bait for conch fishing.
“End use is not up to a government agency,” he said. “Our job is to set sustainable harvest rates, and then leave it up to market demand as to best use.”