High-tech equipment used to study monster N.B. fish

A Mount Allison professor is doing some high-tech research on a monster fish in New Brunswick's St. John River.

Dr. Matt Litvak and his colleagues are trying to learn more about the elusive Atlantic and shortnose sturgeon, including where and when they spawn, migration patterns and whether the caviar from supposedly farmed sturgeon are truly from sustainable sources.  

He hopes the information he collects can be used to build a database to determine whether caviar sold on the international market is from legal, farmed sturgeon or from the wild population

Sturgeon are not something you see every day, but Litvak, who has been researching sturgeon in the St. John River since 1998, says they are around.  

In fact there are an estimated 4,500 shortnose sturgeon in the river, give or take 200, Litvak says. Population estimates for Atlantic sturgeon are unreliable.

The largest Atlantic specimen ever caught in the river measured nearly 4½-metres long and weighed a whopping 360 kilograms. Shortnose specimens usually only reach about 24 kilograms.

Sturgeon, with their plate-like armoured scales, are an ancient fish that have remained nearly unchanged since the days of the dinosaurs.

High-tech research on ancient fish

To determine whether sturgeon caviar has been obtained sustainably, Litvak is isolating stable isotope signatures from the tissue and eggs of the fish. 

Forensic analysis of isotope levels give scientists an idea of what the fish eats.

For instance, a sturgeon that eats primarily a marine-based diet will have a much different signature than a fish that is fed at a fish farm.  

If researchers can figure out what the fish eat then they have a good idea of where the fish, and thus the prized caviar, came from.  

Another aspect of Litvak's research includes tagging adult sturgeon in the St. John River with pop-up satellite tags attached to the dorsal fin to track their movements.  

The tags relay information such as how deep the fish dive, the amount of time they spend in salt water versus fresh water and other seasonal migration patterns which give scientists a much better understanding of sturgeon lifecycles.  

The 15 to 20 centimetre-long tags, which cost about $3,500 each, are designed to break off after a certain period of time.

The tags periodically transmit bursts of data to satellites but more data can be collected if the tag is retrieved.

Litvak says that is difficult to do because of water turbulence in the Bay of Fundy and problems targeting the small devices using weak receivers.    

Commercial fishery

Population estimates for the larger Atlantic sturgeon are unreliable.  

Both species produce caviar, though only the Atlantic variety is allowed to be fished.

Atlantic sturgeon caviar isn't cheap, costing nearly $2,000 per kilogram.  

Litvak said potential risks to sturgeon include overfishing. The commercial fishery for the Atlantic sturgeon usually harvests between 350 and 400 fish per year.

Without a better understanding of the sturgeon population, the fish could be at risk of being over harvested.  

Other sources of concern for sturgeon

Litvak lists a number of concerns including potential habitat and spawning ground destruction from poorly managed hydroelectric plants in the St. John River.  

"If the plants are poorly managed, then there is the possibility the fish fry or eggs could be left high and dry when the water level is low," he said.  

Litvak also said recent changes to the federal Fisheries Act have him very concerned.

"When you move away from evidence-based decisions, removing science," policy decisions based on speculation can result in serious problems for fisheries, he said.   

Both the shortnose and the Atlantic sturgeon are listed as endangered species in the U.S. In Canada, the larger shortnose is listed as a species of special concern under the Canadian Species at Risk Act and the more common Atlantic sturgeon is listed as threatened.  

These classifications do not carry the same protections as a species listed as endangered.

Litvak says there needs to be more collaboration between the two countries when it comes to protecting species since fish and other wildlife do not respect international boundaries.  

Risk to people

When asked if these monster fish pose any risk to humans, Litvak said, "not unless they're worried about being kissed to death."  

The gentle giants are bottom feeders, using their shovel-like snouts to dig up mollusks, other invertebrates and small fish from the sediment.    

However, he said he has heard stories from the United States where boats have caused the fish to jump out of the water, hitting boaters and injuring them.