It's Time to Save Our Threatened River Herring
Posted August 2, 2011
Among all the awe-inspiring phenomena of the natural world, the immense spawning runs of alewife and blueback herring along the Atlantic Coast ranks highly. Not long ago, these platinum, big-eyed fish poured into estuaries and up rivers in such overwhelming numbers that, to the human eye or imagination, a river might seem to run backward, for an instant. Collectively known as “river herring,” they fed Native Americans and early settlers—and they still nurture our ecosystems. Not only are they fundamental to both marine and freshwater food webs as prey species, but those fish that die after spawning also fertilize their natal streams, much like salmon.
Unfortunately, after centuries of overfishing, dam construction, water pollution and other harms—which now increasingly includes the effects of global warming—the annual pulses of river herring have slowed to a relative trickle. And there’s concern that they could disappear entirely in the future. So today NRDC is submitting a petition to the federal government to list the alewife and blueback herring as “threatened” species under the Endangered Species Act (ESA).
Alewife (Alosa pseudoharengus)
Source: U.S. Fish and Wildlife Service
The precipitous decline of river herring is made clear by fish counts and records of commercial landings. From 1950 to 1970, the Atlantic catch averaged over 50 million pounds per year; in the last decade, however, an average of just over one million pounds has been hauled in, a plunge of 98 percent. Meanwhile, in individual rivers where millions once swam, returning river herring number in the thousands, or even hundreds. To cite just a couple of examples, counts in Connecticut River fell from an average of 5.4 million from 1981 to 1995, to an average of 1 million by 2001, to an average of only 300,000 by just 2008. And in the Susquehanna River, which drains into Chesapeake Bay, blueback herring passed by the Conowingo Dam East fish passage dropped from almost 285,000 counted fish in 2001 to just 4 fish in 2010. The same story is playing out up and down the Eastern seaboard.
From the start, the industrial development of the Atlantic seaboard took its toll on the river herring. Milldams obstructed their passage to spawning beds, and factories poured toxics into streams – problems that persist, in part, to this day. Nutrient pollution from farms and cities is increasingly a problem, fueling algal blooms that leach oxygen from rivers and bays, creating “hypoxic zones” that cause large die-offs of fish and impassable stretches of river. Now there’s a new threat in the New England ocean waters where river herring congregate to overwinter – more and larger factory trawlers are fishing for ocean herring and mackerel, and are scooping up significant numbers of river herring in the process.
Blueback Herring (Alosa aestivalis)
Source: U.S. Fish and Wildlife Service
Climate change is compounding the river herring’s plight, since they depend on subtle cues of temperature and chemistry. Warmer waters might shift anadromous fish runs earlier in the season, out of synch with their other seasonal conditions, or even away from their natal rivers, as well as promote hypoxic conditions. Additionally, as increasingly volatile weather patterns emerge, larger storms will make spawning more difficult and sweep away more eggs and juveniles (and only 1 percent typically survives, as it is).
Alewife and blueback herring each deserve to be listed as a whole, at the species level, for if they’re to adapt to climate change, it’s crucial to maintain the full suite of their genetic diversity. Barring that, they should be listed as distinct population segments (DPSs), which are treated as species under the ESA. For both fish, the DPSs would include the Central New England, Long Island Sound, and Chesapeake Bay regions (and for the alewife, the Carolina region as well). Since river herring return to their natal stream to spawn, each river represents a partially isolated and unique population; however, a certain amount of “straying” into neighboring rivers does occur within DPSs, which fosters commonalities. For example, northern alewives can tolerate colder water temperatures better than southern populations, thanks to antifreeze qualities in their blood.
As of yet, river herring don’t have a federal fishery management plan to help them, like many fish do under the Magnuson-Stevens Fishery Conservation and Management Act (MSA). Four states have prohibited their harvest—Connecticut, Massachusetts, Rhode Island, and North Carolina—but that hasn’t proved enough to bolster their numbers. The fish need the type of comprehensive management and protection afforded by the ESA, which entails an official recovery plan. Hopefully it would require new measures for reducing river herring catch in ocean waters --- measures that have been resisted to date – as well as habitat protection, like dam removal (or improved fish ladders) and restrictions to minimize nutrient runoff in rivers.
NMFS has 90 days to determine if our petition shows that a “threatened” listing for river herring may be warranted. If they agree, then the agency will have another year to decide if it will, in fact, list the fish. In the meantime, please lend your voice to the Atlantic river herring’s case, so that NMFS makes the right decision. The staggering yearly migration of river herring was once a symbol of North America’s biological richness and fecundity. With our vigilance, it can be so again.
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