Fire hoses and a vacuum truck came to the rescue Sunday as Little Egg Harbor Township, N.J., coped with the sudden death of an estimated 20,000 small fish in Great Bay.

"The smell was getting pretty onerous," Township Administrator Garrett Loesch said Monday.

Boaters and residents began reporting "peanut bunkers" - small juveniles of the menhaden family - floating on the surface near Osborn Island late Friday, he said.

Their numbers continued to mount Saturday and Sunday before the township's public works department, Municipal Utilities Authority, and volunteer firefighters arrived to take them away.

A much larger kill occurred last Tuesday in Raritan Bay, off Keansburg on the northern shore of Monmouth County.

State Department of Environmental Protection officials said the likely cause of both kills was low oxygen levels in the shallow bays.

Spokesman Larry Hajna said a predator species, such as bluefish, may in both cases have chased a school of the bunkers into the bays, where they quickly depleted what little dissolved oxygen was available. Warm water holds less dissolved oxygen than cooler water.

A DEP monitoring buoy showed the water temperature in Little Egg Harbor on Monday afternoon to be 79 degrees, and the dissolved oxygen to be 7.4 milligrams per liter. That number is normally sufficient to support most marine life, but it can drop sharply at night.

Several environmental groups said Monday they had no evidence that water heated by electric generating plants to cool their turbines, which is then discharged into waterways, played a role in the kills.

But they noted that heated discharge water, along with runoff from septic systems and nutrient-rich farm fertilizers, can contribute to eutrophication - the growth of oxygen-depleting vegetation - in inland waterways.

"The more difficult question is whether all these stressors are pushing these bays to where they exist right on the edge of being in the danger zone, so that a relatively short period of extended heat pushes the levels so low the fish kills happen," Tim Dillingham, executive director of the American Littoral Society, wrote in an email.

Peanut bunker, like mature menhaden, are caught commercially in large numbers off the Atlantic Coast for use as bait fish. Bunker is a nickname for menhaden.

Bob Considine, the DEP's director of communications, said the menhaden population off New Jersey appears to be exceptionally large this year. He said the department had tested samples of the dead fish and "none appear obviously diseased."

Loesch said that the fish kill was the first in Little Egg Harbor in the 39 years he has lived there. When the scale of it became apparent, the township council authorized the payment of overtime for the public works department.

On Sunday, volunteer firefighters and public works crews working in small boats trained fire hoses on the heaps of dead fish, sending them into the lagoons around Osborn island.

There, MUA employees used a vacuum truck to suck the fish up and transport them to a landfill.

"You can get a lot more volunteer firemen out on a Sunday than you can on a Monday," Loesch said. "We were lucky."