What's causing the death of shovelnose sturgeon in the Wabash River is a mystery that the Department of Natural Resources (DNR), Department of Environmental Management (DEM), and scientists at Purdue University are trying to uncover। Since mid-July [2007] about 100 of the odd-looking fish have been found dead along a stretch of the Wabash from Delphi to Attica [Indiana].On 22 Jul 2007, DNR Conservation Officer, Matt Tholen, found 35 in just a mile and a half (2.4 km) near the Tippecanoe-Warren County line [in west central Indiana]. "They've been found individually. You'd find one, then 10 or 20 yards (9-18 m) down find another," Tholen said.Whatever it is seems to only affect average size sturgeons about24-32 inches (60-80 cm) in length. "We've found no small fish, and no other (species) of fish," said Tholen, who is also public information officer for District 3.Tholen and Officer Todd Pekny have taken samples of the dead sturgeon to Purdue University for testing. "They're running tests on fat tissue," Tholen said. "I've never seen anything like this and we're just waiting on the results."Shovelnose sturgeons are found in Indiana's larger rivers like the Wabash, as well as the Missouri and Mississippi rivers.Besides being a flavorful meat fish, especially when smoked, they have become more popular for their roe, or eggs, which are used for caviar.
Although larger species of sturgeon in central Asian waters at one time provided most of the world's supply of caviar, due to habitat degradation, pollution, and overfishing, smaller species like the shovelnose have been harvested for the delicacy.Shovelnose are not considered endangered at this point, but there are concerns, according to a series of studies completed in 2006 by Purdue University fisheries biologist, Trent Sutton. "The problem with sturgeons in general is that they are a long-lived fish that take a long time to reach sexual maturity," Sutton said.The shovelnose, the smallest of sturgeons, reaches sexual maturity between ages 6 and 9, and spawns every other year. Like other sturgeon species it is particularly vulnerable to overfishing because of the time required to breed and regenerate their numbers.Sutton's research found the Wabash River population appears to be stable, but his sampling uncovered few young fish in the river. "This raises a few red flags," Sutton said. "This means that either the females aren't laying eggs or that they aren't spawning at all -- both of which would have serious ramifications."But this year [2007], according to DNR Chief of Fisheries, Bill James, a spawning population was discovered in the general area of the recent deaths. To James that indicates a healthy population overall. "There was a successful spawning this spring, and shovelnose sturgeon in the Wabash are deemed a very healthy population."That is despite pressures from invasive aquatic species, fishing pressures, and transporting some sturgeon to other states to reintroduce their populations.He also explained the dead fish had no signs of obvious disease, and because the fish don't appear to have died in mass as might occur in a contaminant spill, James speculates it may be several causes."The fish that died appeared healthy and not as if their food supply was affected. It may be an incremental build up of stresses -- spawning stress, low water flows this summer, or other environmental conditions," said James.Both dead fish and live samples collected recently are being tested for comparisons, but no obvious cause has been determined yet.In the meantime Tholen said he wants the public to be aware of the unexplained sturgeon deaths. If anyone has information that may be viable to the investigation call the local Indiana Conservation Officer District #3 office at 765-447-9582, or the local sheriff's department dispatch on the non-emergency number.[Byline: Kevin Howell]
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