Fisheries partnership aids sturgeon restoration
Efforts to restore Chesapeake Bay's sturgeon population took another step forward today, when researchers lifted a 5-foot sturgeon into a tanker truck for its journey to a spawning facility in Maryland.
The 80-pound Atlantic sturgeon (Acipenser oxyrhynchus) was captured last Friday in a James River gill net by commercial fisherman Kelly Place. Place, along with fishermen George Trice and Jimmy Moore, are partners in a collaborative project with Dr. Chris Hager, a fisheries scientist in the Sea Grant Marine Advisory Program at VIMS. Their partnership is part of a larger sturgeon monitoring and restoration effort among state and federal agencies in Virginia and Maryland.
The 5-foot fish is one of the first sturgeons captured in Virginia waters large and mature enough to hold significant promise for spawning efforts. Captive spawning is one part of a management strategy designed by the Atlantic States Marine Fisheries Commission (ASMFC) in the mid-1990s to help restore wild sturgeon stocks to levels that will provide for a viable population and sustainable fisheries in Chesapeake Bay.
"These fish can't come back on their own," says VIMS fisheries scientist Dr. Jack Musick. "There are simply not enough spawning adults."
Restoration efforts also include a coast-wide moratorium on sturgeon harvesting, which was enacted by the ASMFC in 1997. Virginia has had a moratorium on sturgeon harvesting since 1974.
Sturgeons once supported the second largest commercial fishery on the U.S. East coast, with a peak landing in 1890 of 7.5 million pounds. But decades of over-fishing and habitat loss forced the sturgeon population into a steep decline. Populations of Atlantic sturgeon are now extirpated in Maryland and at historically low abundance in Virginia, where remnant populations exist in the James and York rivers.
Efforts to restore Chesapeake Bay sturgeon populations involve numerous stakeholders, including commercial watermen, the Maryland Department of Natural Resources (MD DNR), the National Aquarium in Baltimore, the Horn Point Laboratory at the University of Maryland's Center for Environmental Science (HPL/UCMES), VIMS, the Sea Grant Marine Advisory Program at VIMS, the Virginia Marine Resources Commission, and the US Fish and Wildlife Service (USFWS). Because sturgeon range up and down the East Coast, the restoration project is coordinated by the multi-state ASMFC.
One of the primary objectives of the restoration effort is to transport any wild-caught sturgeon large enough to be reproductively mature to spawning tanks in Maryland. One set of tanks is operated by the Finfish Aquaculture Program at the University of Maryland's Horn Point Laboratory. Another spawning facility is operated by Mirant Corporation, an energy provider with four power plants in the Chesapeake Bay watershed.
To date, the only sturgeon in the aquaculture facilities large enough to spawn have come from the Hudson River in New York. Female sturgeon typically do not reach sexual maturity until they are about 12 years old and about 6 feet long. Males mature slightly earlier, at around 7 years old. The fish may live up to 60 years and grow to 14 feet.
Researchers are particularly excited about the recently captured sturgeon because its size places it at about the length and age at which sturgeon typically become capable of reproduction. It remains unknown whether the fish is a male or female, but the researchers are hoping it's the latter.
"It's the proper time of year for sturgeon spawning," says Musick, "and this fish is about the right size for a female to begin releasing eggs."
The researchers are also pleased that the fish was collected far enough up a Virginia tributary to suggest spawning activity. James River fish historically spawned in tidal freshwaters far upstream, near the site of present-day Richmond.
The James River watermen caught the sturgeon during a fishery-independent research project designed to throw light on the sturgeons' abundance, habitat, and seasonal movements within local waterways. Another aspect of the study aims to understand how sturgeon are being affected by fisheries bycatch.
The study is funded by a Fisheries Resource Grant from the Virginia Sea Grant Program to Place and Hager. These grants are designed to provide Virginia watermen with an opportunity to use their knowledge and experience to help develop new fisheries gear, restore or enhance fishery habitat, improve aquaculture operations, or advance technologies for processing and marketing seafood.
"The grants allow fishermen to participate and improve the situation," says Hager. "Their knowledge and experience can go a long way toward our shared goal—to re-establish a sustainable fishery for sturgeon in Chesapeake Bay.”
Musick and his graduate students are pursuing a related study to better understand the sturgeon's spawning behavior and habitat requirements. Such knowledge is needed to guide the selection of any future stocking locations.
"We're working to find the optimal spot for restoration," says Musick. One thing the researchers already know is that sturgeons need a hard-bottom for attaching their eggs. Because human activities in the Chesapeake Bay watershed have greatly increased the amount of silt blanketing the bay floor, hard bottoms are now rare. Thus "one option we're considering is the addition of rocks to certain areas," says Musick.
Another prerequisite for sturgeon restoration is determining the genetic make-up of East Coast sturgeon stocks. Scientists remain unsure if the Chesapeake Bay sturgeon population is genetically unique, or represents a blend between Hudson River and South Carolina populations. Scientists in Maryland will help answer this question by taking a sample of DNA from the James River fish and analyzing its genetic signature.
If there is a unique sturgeon gene pool in Chesapeake Bay, those fish should be used for restoration, says Hager. "We need to get some Virginia genes in the spawning program," adds Musick.