The American shad’s Atlantic population remains at a historic low, despite longstanding commercial fishing bans in several states and millions of dollars invested in restoring the fish’s habitat.

Shad in net

Millions of dollars have been spent to restore the American shad’s Atlantic population.

That sober news comes from the most comprehensive survey yet of the species’ status on the East Coast and the first of any kind in 13 years. The sprawling assessment by the Atlantic States Marine Fisheries Commission designates the shad population as “depleted” from Maine to Florida.

“There should be a lot more shad than there are out there,” said Michael Bailey, a U.S. Fish and Wildlife Service scientist and one of the assessment’s authors.

In the Chesapeake Bay region, the study suggests that the rate of death among adult shad — a key measure of a population’s health — is “unsustainable” in the Potomac River but “sustainable” in the Rappahannock and York.

Once one of the largest commercial fisheries along the coast and around the Bay, shad catches have bottomed out at about 1% of their late-1800s levels. Although the shad fishery has all but disappeared in the Chesapeake, scientists contend that the species serves a critical ecological role in the estuary as a vital link in its food chain.

But shad are an anadromous species, meaning they spawn in freshwater rivers but spend most of their adult lives in the ocean before returning to their native river to reproduce when they are 4 or 5 years old. Because shad rely on so many different habitats, they face a barrage of challenges through all stages of life.

The species’ continued struggles are mostly blamed on the amount of potential habitat blocked by dam construction, a loss of about 40% of its historic range. But shad also face threats from climate change, polluted water, deadly run-ins with hydroelectric turbine blades and getting eaten by larger fish.

The Marine Fisheries Commission, which regulates migratory fish in state waters along the Eastern seaboard, is grappling with whether more actions are needed to buoy the stock. The commission’s shad management board tasked a scientific panel Aug. 4 with recommending potential measures.

Fishery managers have been pulling regulatory levers for decades to help shad rebound but with little progress to show for it.

Commercial landings plummeted from about 50 million pounds at the beginning of the 1900s to 3.8 million coastwide by 1980. That year, Maryland imposed a moratorium on shad fishing. The Potomac River’s regulators followed suit in 1989; Virginia closed its rivers to shad fishing in 1994.

Ocean catches have been largely prohibited since 2005, but the new assessment finds no evidence that the action has breathed new life into the population.

While fishing was cut back, massive efforts were undertaken to boost the population. Pennsylvania, Virginia, Maryland and Delaware launched hatchery operations to rear shad for release in their rivers. Hundreds of millions of larval shad “fry” have been stocked in recent decades.

Meanwhile, major efforts were made to reopen historic spawning areas to fish returning from the sea each spring. Since the early 1990s, tens of millions of dollars have been spent opening more than 1,000 miles of Bay tributaries to migrating shad. Where possible, dams have been removed, but most of the reopening has been achieved through the construction of fish passages.

Research has shown that shad use those constructed passages at relatively low rates.

Although scientists have made significant strides in monitoring shad, they were unable to assess for the 1,200-page report whether the coastwide population’s adult death rate is sustainable. At a smaller scale, they were confident enough to make a call for eight of the 23 river systems they studied — with three being declared as unsustainable (the Connecticut, Delaware and Potomac) and five as sustainable (the Hudson, Rappahannock, York and Neuse as well as Albemarle Sound).

Some fishery experts were caught off guard by the report’s bleak assessment of the Potomac population. By 2014, shad abundance there had surpassed the goal set by the Chesapeake Bay Program, the federal and multi-state effort that manages the restoration of the estuary.

After gaining in size until as late as 2005, the Potomac shad stock has leveled off, according to the Marine Fisheries Commission report. Fishery scientists aren’t sure why that is happening, but they think young shad might be being eaten by the region’s rising numbers of invasive species, such as blue catfish and snakeheads.

“Predators can have a disproportionately large impact on year class success when fish populations are at such low levels, as is currently the case,” wrote a scientific panel tasked with reviewing the assessment.

Scientists suspect that the Potomac’s shad troubles may lie elsewhere — in the Atlantic. Larger fish may be eating them at sea. They also may be falling victim to bycatch — commercial fishing that unintentionally kills fish other than the targeted species.

Uncertainty is a common theme in the report. For instance, while adult mortality is monitored, there is “almost no information” collected about young shad, Bailey said. That knowledge gap prevented the report’s authors from determining whether the fish’s coastwide death rate is at acceptable levels. They tied their “depleted” characterization to a sharp decline in coastwide landings since the 1950s and a lack of clear evidence of a rebound.

The fish tend to return to spawn in the rivers where they hatched, but those individual populations are thought to become mingled at sea. The sea connection will become increasingly vital as climate change warms the ocean, prompting shad to either die off in lower latitudes or “hopscotch” their way northward toward more-hospitable waters, said Karin Limburg, an ecologist at the State University of New York in Syracuse.

One of the biggest steps that fishery managers can take is to open the Susquehanna River to shad migration, even if it means “taking down” the Conowingo Dam, she said. The existing passages at the dam and elsewhere aren’t moving enough fish upstream. The river hosts the largest untapped spawning ground for the fish on the East Coast. The dam’s owner, Exelon Corp., is working on a deal that would allow the company to continue operating it for the next 50 years.   


(1) comment

Jim Cummins

It is too bad that the ASMFC did not do a better job with their public statements about the findings of their assessment. As your article correctly states, the study merely "suggests" that the rate of death among adult shad is unsustainable in the Potomac River. The ASMFC's own Peer Review Panel’s recommendation was that the report's data quality issues are of such a concern that the output from the current Potomac model “should not be used to provide estimates for management purposes.” In other words, the Potomac shad population MAY OR MAY NOT be sustainable. To be conservative, the ASMFC chose to emphasize the MAY not be sustainable.

In addition, the study was looking at changes that occurred from 2007-2017. The Potomac’s shad population rose dramatically from the mid-1990s to the beginning of that study period, and now there “MIGHT” be at a flattening out or plateau.

Another important factor to consider – there needs to be better consideration of the mortality of the Potomac population while they are in the ocean, which is 4/5s of their life. Shad are only in the Potomac for about2 months/year after they reach maturity at 3-5 years of age. The Potomac shad population’s strong regrowth over the past 25 years is an outlier, sadly, most other shad populations have been and still are very depressed, some remaining at all-time lows. Therefore, the Potomac-origin shad currently make up a disproportionally large percentage of the mixed-ocean population. Thereby, predation in the ocean and fisheries by-catch (by-catch is when shad are caught in fishing gear meant for other species) are likely occurring at unnaturally high levels upon the Potomac shad population. For this reason, for many years in my annual report on the Potomac River shad restoration which I ran I noted that the Potomac shad population will have difficulties fully recovering until the other shad stocks are also restored. It is likely that we are witnessing that difficulty.

So any plateau in the Potomac shad population is much more likely a consequence of ocean predation and by-catch than upon the in-river brood stock collections which are performed to collect shad eggs for the restoration of other rivers. I strongly recommend that we keep supporting shad restoration in other rivers! I am hoping that future efforts and technology will permit a better understanding of ocean mortality factors.

In closing, restoring a fishery is a different task from restoring a fish. Recreational shad fishing has been completely closed in the Potomac since 1982 and, due to that full closure, interest in the fish dwindled and was lost for over a generation. Shad became not just a rare fish in the Potomac, they became a forgotten fish. Until recently just about the only people with any memory of shad were over 70 years old. The restoration stocking of the Potomac river would not have happened without the USFWS’s Harrison Lake National Fish Hatchery, and thanks to them and to the involvement of tens of thousands of students and teachers in the Washington metropolitan area who for over 25 years have helped by hatching shad eggs in their classrooms and stocked them into the Potomac, interest in the shad and in angling for them has also grown rapidly and strong. The Potomac’s sister shad restoration initiative, which we named the “Schools-in-Schools” shad stocking program, began in 1996 and is still active. The Potomac’s shad population is strong enough, it is past time to begin permitting and encouraging a limited recreational harvest to sustain, no, to improve this renewed interest.

Thanks for the report, please give my best to Karl!

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