Biologists believe dramatic drop of blueback herring in Connecticut River caused by increase in striped bass
.By STAN FREEMAN
sfreeman@repub.com
HOLYOKE - Blueback herring once teemed in the Connecticut River, with well more than a half million returning upstream from the ocean to spawn in some years in the 1980s.
But this year, only 39 have been counted at the Holyoke Dam, worrying fish biologists who say the fish's growing scarcity may be the result of another fish's increasing abundance.
"Herring are a prey item for striped bass, and one theory is that it's because of the dramatic increase in striped bass populations over the last 15 years," said Kenneth I. Sprankle, the Connecticut River coordinator for the U.S. Fish and Wildlife Service.
Blueback herring are anadromous, which means they are born in fresh waters, such as rivers and streams, then travel out to sea to spend much of their lives before returning upriver to spawn.
The spawning runs of anadromous fish, such as herring, Atlantic salmon and American shad, on the Connecticut River were all but ended in the 1800s when dams were built for water power. However, at the Holyoke Dam and others, fish lifts were built after World War II to try to re-establish the runs.
The first few blueback herring, which average less than a foot in length as adults, were counted in Holyoke in 1957. The numbers increased sharply in the 1970s, and in 1985, about 632,000 were counted at the dam. In the 1990s, though, the returns of herring fell dramatically, going from 411,000 in 1991 to 2,700 in 1997 to fewer than 100 in 2006.
Meanwhile, in the 1970s overfishing, water pollution on spawning grounds and loss of habitat took their toll on striped bass, a favorite of fishermen. In 1979, Congress passed the Emergency Striped Bass Act that resulted in restrictions on catches and programs to raise young stripers in fish hatcheries for release in the wild.
The measures succeeded. In 1982, it was estimated there were about 5 million striped bass in Atlantic Coast waters. But by 2005, the population approached an estimated 65 million.
Striped bass can exceed 50 pounds - with a record catch in Massachusetts coastal waters of 73 pounds - and they are voracious eaters of smaller fish, such as herring, alewives and menhaden.
Caleb H. Slater, head of the anadromous fish program for the state Division of Fisheries and Wildlife, said, "In the early nineties, there were still an incredible number of blueback herring, but they could have been so many because there was nothing to eat them."
However, fish biologists say a second factor may be at play in the decline of herring. They are often a bycatch, or unintended catch, when commercial fishermen haul in sea herring, a different species.
"They take millions and millions of pounds of sea herring," Slater said. "The observers say there is a small bycatch (of blueback herring.) But you have to realize if they're catching millions of tons, even a small bycatch can be the entire run of a small river."
While down from their historic highs, the counts of Atlantic salmon and American shad at the Holyoke Dam have been holding steady. Since 1999, the number of returning salmon counted at the dam has varied between 43 and 214, and the number of returning shad has varied between 116,000 and 370,000. Through Sept. 1 this year, 76 salmon were counted at the dam and 162,000 shad were counted.
However, the number of Atlantic salmon, nicknamed "king of the game fish," is far lower than had been hoped for when fishlifts were added to dams on the Connecticut River. It had been hoped as many as 40,000 salmon a year would return to the river, turning it into a major salmon fishery.
"Salmon numbers remain disappointing," Slater said.
Wildlife officials continue to raise young salmon in hatcheries for release on the river, in hopes they will "imprint" on it and return to spawn, he said.
"We see a good number of smolts, two-year-old fish, going back to the ocean. That's the good news. The part of the life history we have some control over seems to be going very well. But they go into the ocean and most never come back. And that's something we see not only on the Connecticut River but also in Maine and elsewhere," he said.
New York officials recently moved to halt commercial fishing of shad on the Hudson River because of low number of returns there. However, fish biologists speculate that the effect of the flows from industrial pipes on the spawning fish on the Hudson is greater than on the Connecticut.
"We're not too concerned about shad," Slater said. "Those numbers (on the Connecticut River) have been stable for the last five years or more."
.By STAN FREEMAN
sfreeman@repub.com
HOLYOKE - Blueback herring once teemed in the Connecticut River, with well more than a half million returning upstream from the ocean to spawn in some years in the 1980s.
But this year, only 39 have been counted at the Holyoke Dam, worrying fish biologists who say the fish's growing scarcity may be the result of another fish's increasing abundance.
"Herring are a prey item for striped bass, and one theory is that it's because of the dramatic increase in striped bass populations over the last 15 years," said Kenneth I. Sprankle, the Connecticut River coordinator for the U.S. Fish and Wildlife Service.
Blueback herring are anadromous, which means they are born in fresh waters, such as rivers and streams, then travel out to sea to spend much of their lives before returning upriver to spawn.
The spawning runs of anadromous fish, such as herring, Atlantic salmon and American shad, on the Connecticut River were all but ended in the 1800s when dams were built for water power. However, at the Holyoke Dam and others, fish lifts were built after World War II to try to re-establish the runs.
The first few blueback herring, which average less than a foot in length as adults, were counted in Holyoke in 1957. The numbers increased sharply in the 1970s, and in 1985, about 632,000 were counted at the dam. In the 1990s, though, the returns of herring fell dramatically, going from 411,000 in 1991 to 2,700 in 1997 to fewer than 100 in 2006.
Meanwhile, in the 1970s overfishing, water pollution on spawning grounds and loss of habitat took their toll on striped bass, a favorite of fishermen. In 1979, Congress passed the Emergency Striped Bass Act that resulted in restrictions on catches and programs to raise young stripers in fish hatcheries for release in the wild.
The measures succeeded. In 1982, it was estimated there were about 5 million striped bass in Atlantic Coast waters. But by 2005, the population approached an estimated 65 million.
Striped bass can exceed 50 pounds - with a record catch in Massachusetts coastal waters of 73 pounds - and they are voracious eaters of smaller fish, such as herring, alewives and menhaden.
Caleb H. Slater, head of the anadromous fish program for the state Division of Fisheries and Wildlife, said, "In the early nineties, there were still an incredible number of blueback herring, but they could have been so many because there was nothing to eat them."
However, fish biologists say a second factor may be at play in the decline of herring. They are often a bycatch, or unintended catch, when commercial fishermen haul in sea herring, a different species.
"They take millions and millions of pounds of sea herring," Slater said. "The observers say there is a small bycatch (of blueback herring.) But you have to realize if they're catching millions of tons, even a small bycatch can be the entire run of a small river."
While down from their historic highs, the counts of Atlantic salmon and American shad at the Holyoke Dam have been holding steady. Since 1999, the number of returning salmon counted at the dam has varied between 43 and 214, and the number of returning shad has varied between 116,000 and 370,000. Through Sept. 1 this year, 76 salmon were counted at the dam and 162,000 shad were counted.
However, the number of Atlantic salmon, nicknamed "king of the game fish," is far lower than had been hoped for when fishlifts were added to dams on the Connecticut River. It had been hoped as many as 40,000 salmon a year would return to the river, turning it into a major salmon fishery.
"Salmon numbers remain disappointing," Slater said.
Wildlife officials continue to raise young salmon in hatcheries for release on the river, in hopes they will "imprint" on it and return to spawn, he said.
"We see a good number of smolts, two-year-old fish, going back to the ocean. That's the good news. The part of the life history we have some control over seems to be going very well. But they go into the ocean and most never come back. And that's something we see not only on the Connecticut River but also in Maine and elsewhere," he said.
New York officials recently moved to halt commercial fishing of shad on the Hudson River because of low number of returns there. However, fish biologists speculate that the effect of the flows from industrial pipes on the spawning fish on the Hudson is greater than on the Connecticut.
"We're not too concerned about shad," Slater said. "Those numbers (on the Connecticut River) have been stable for the last five years or more."