Dead Fish Washing Up On Shores Of North Falmouth

By: Michael C. Bailey
Published: 07/22/11

What is killing sportfish off the coast of North Falmouth?

“We don’t know. That’s the answer,” said George R. Hampson of North Falmouth, who first brought the issue to the town’s attention.

Over the past few weeks, the Falmouth Natural Resources Department and the Massachusetts Division of Marine Fisheries (DMF) have received reports of dead bluefish, striped bass, and scup floating in the waters of Buzzards Bay. R. Charles Martinsen III, assistant director of the Natural Resources Department, said dead fish have also washed ashore in the New Silver Beach area, as far south as Stony Beach in Woods Hole, “and we’ve also had a handful of reports from Bourne.”

“They’ve shown up in various stages of decomposition,” he said, “and with no obvious cause of mortality.”

Mr. Hampson, a retired biologist and chairman of the Falmouth Coastal Pond Management Committee, said he first learned of the problem about three weeks ago after receiving a phone call from a friend living in the Chapoquoit area, who reported a small number of badly decomposed fish washing ashore.

“The lifeguards gathered them up and threw them in the garbage,” Mr. Hampson said, but he got another opportunity to inspect the carcasses when more washed ashore. Unfortunately, they were “too badly decomposed to be examined” in order to determine a cause of death.

“There were small numbers at first, but they kept coming,” Mr. Hampson said, and it was during the July 4 weekend that the situation took a more dramatic turn. He received a phone call from friends living in the Silver Beach neighborhood who reported “fish all over the place.”

The resident estimated as many as 50 dead fish had washed ashore. Mr. Hampson did not have a more precise count, but indicated his friends’ initial estimate was not a great exaggeration.

Since that weekend, dead fish have continued to wash up on shore, mostly along the North Falmouth shoreline.

Mr. Hampson said this is not the first time this has happened. Dead fish washed up on Falmouth shores in 2009, but much less frequently and in much smaller numbers, he said.

Local and state officials have not called this a proper “fish kill,” a term referring to instances in which a large number of fish die off at once due to some natural cause.

Fish kills are not unheard of on Cape Cod, but occur more often in closed bodies of water due to a “low-oxygen event.” Such events are often the result of rampant algae growth; as large algae blooms die, they consume the dissolved oxygen in the water and choke off animal life.

Low-oxygen events are less likely in the open ocean, where natural forces such as wind and the tides keep the waters active and well-oxygenated.

Mr. Hampson said he personally would not completely rule out a low-oxygen event, but said if that was indeed the cause, it would have happened in a more inland body of water. He presented one theoretical scenario in which bluefish follow schools of menhaden into a cove, where they become trapped. The bluefish die due to a low-oxygen event, their bodies wash out to sea with the tides, then are washed back onto shore when the tides shift.

However, Paul Caruso, senior marine fish biologist with the DMF’s recreational fisheries program, stated that “the clues are not leading us in that direction.” He added that a low-oxygen event occurring in more open waters, while within the realm of possibility, would have affected more than just the three specific species that have been catalogued thus far.

Ocean fish kills are usually attributed to bacterial infections, disease, parasites, or a toxic substance in the water, but according to Mr. Caruso, when it comes to natural causes, “A lot of these things are transitory…they happen, and we often don’t know why they happen.”

Another possible cause is man-made. Mr. Caruso said commercial fishermen sometimes dump dead fish back into the ocean, but fish that have been caught by hook or net and later dumped would show corresponding physical damage, e.g., fish hook damage around the mouth or net marks on the body.

Mr. Martinsen did not speculate as to a cause for the fish kill, but he noted that recent beach water quality testing in the area has come up clean.

The Barnstable County Department of Health and the Environment conducts weekly water quality testing of the Cape’s public beaches. According to results posted on the department’s website (www.barnstablecountyhealth.org/bathing-beach-water-quality), the southern portion of nearby Megansett Beach failed its July 12 test but passed its follow-up test conducted the next day.

Roxanna M. Smolowitz, an adjunct scientist with the Marine Biological Laboratory in Woods Hole who specializes in diseases affecting fish and shellfish, has been asked to examine the fish in order to determine a cause of death.
“We’re hoping to get her fresh samples so she can help us solve this puzzle,” Mr. Martinsen said.

“If we had a fresh fish, we could tell what killed it,” Mr. Caruso said, “but you really have to be Johnny-on-the-spot…in nature, if you’re not on top of things right away, you won’t know the cause. That might end up being the case here.”

Anyone finding dead fish along the shore, particularly in the North Falmouth area, is asked to immediately contact the Falmouth Natural Resources Department at 508-457-2536 or 508-495-7334.