Volume 13, Numbers 4 • September-October 1995

Sturgeon -- Looking Ahead

By Merrill Leffler

[sturgeon] That giant 500-pound sturgeons once roamed the bottom waters of the Chesapeake Bay tributaries and were once part of thriving Bay fishery may come as a surprise to those who associate sturgeon caviar with Russia's Caspian Sea. That these ancient creatures are no longer natives to the Chesapeake should be less of a surprise, conditioned as we are to the impact of human activities on other once-abundant species -- oysters and shad and herring and submerged grasses.

Atlantic sturgeon (Acipenser oxyrichus) -- which date as far back as the Cretaceous period 150 million years ago -- have fared even worse perhaps because of their special habitat needs, let alone their peculiar biology, says Dave Secor, a fisheries scientist at the Chesapeake Biological Lab, part of the University System of Maryland Center for Environmental Science.

Cruising low to the river bottom, their hanging whiskers on the alert for potential food, sturgeon suck up benthic molluscs, worms, gastropods, and other inhabitants of sediment. Yet during spring and summer in the Chesapeake, it is these bottom habitats that are often starved for oxygen, thus making a desert of some sturgeon feeding grounds.

Then there is the matter of their slow sexual maturity -- for males, 9 to 12 years, females at least 14 years. If they aren't netted by commercial and recreational fishermen before maturity, females are often harvested at first maturity for their valuable roe. That is the case in the Hudson River where a dozen or so sturgeon fishermen operate, according to Jill Stevenson, a graduate student working with Secor. A mature female sturgeon may bring a fisherman two or three thousand dollars for the roe; then there is a market for the flesh as well, known in New York as "Albany Beef."

Even when sturgeon do reach maturity, they produce a relatively small number of eggs -- ten times fewer than the number of eggs produced by striped bass or shad. Furthermore, unlike striped bass which release fertilized eggs into the water, sturgeon deposit their large, sticky eggs on hard surfaces. Siltation of bottom habitats and the loss of submerged grasses may have greatly reduced the areas that sturgeon need to successfully reproduce. There is no evidence of reproduction in Bay waters in the more than 20 years -- the sturgeon that have been spotted are thought to be visitors from other estuaries where there are still remnant populations.

Despite these seeming odds against restoring sturgeon to the Chesapeake, Dave Secor is an optimist about the potential for success and has been working with the Maryland Department of Natural Resources, with the U.S. Fish and Wildlife Service, with NOAA's National Marine Fisheries Service, with the Hudson River Foundation and with Maryland Sea Grant to try to determine what it will take to bring sturgeon back to the Bay. Such a restoration, he says, will depend on using hatchery-produced sturgeon.

Since 1993, the USFWS Northeast Fishery Center in Lamar, Pennsylvania, has been producing large numbers of juveniles from large sturgeon captures in the Hudson River. While young sturgeon are already being stocked in the Hudson River, some basic questions need answers if there is to be a good chance of survival. What kind of habitats should juveniles be stocked into? What kind of environments would best promote populations to reproduce? Do we even have sufficient habitats in Bay waters anymore?

Overfishing may have reduced sturgeon numbers, but have habitat problems prevented them from reestablishing themselves? For example, how does hypoxia (severe oxygen depletion) in vast stretches of bottom waters in spring and summer affect sturgeon behavior? It is questions such as these that Secor is investigating in the lab with small hatchery-reared fish.

Raising young sturgeon has been a new experience and a challenge to keeping them healthy, says Secor. Because they hug the bottom of the tank where everything collects (for instance, uneaten food, feces), they are quite prone to bacterial infection -- consequently, he has had to keep the tanks immaculate, while treating the fish with antibiotics. They are now large enough for the first experiments, which will study the combined effects of fish size, hypoxia and temperature on growth and survival. Similar laboratory experiments will be repeated next year as well, to see if older fish respond differently to similar conditions. These experiments will be coupled with current monitoring of bottom habitats and the feeding habits for Atlantic sturgeon in the Bay. "Habitats in the Bay could be measured in terms of their potential contribution to sturgeon growth."

Within the next couple of years, he hopes, it will be possible to determine those habitats appropriate for tagging and release. "Despite the uncertainty about the success of sturgeon reintroduction in the Chesapeake Bay, we will never know unless we try," says Secor. The disappearance of sturgeon from the Bay, he points out, "was brought about by centuries of exploitation and alterations to their habitat. Their recovery would be an important indicator of improvement of water quality, habitat and management of our fisheries resources."

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