Doug Arnold is a widely quoted University of Minnesota mathematics professor when it comes to applying math to everyday problems, such as the odds of winning the Powerball jackpot.

But can he solve the riddle of Louis Spray's disputed world-record muskie?

"The mathematics does not give an absolute resolution to the controversy," said the director of the Institute of Mathematics and its Applications. "But in my view, it's unlikely the fish is 63 inches."

That clue could tip the scales against Spray, whose 1949 world-record muskie from Wisconsin's Chippewa Flowage has been challenged by an Illinois group. The National Fresh Water Fishing Hall of Fame is reviewing Spray's record, which is why Arnold was invited to give his unbiased opinion on the controversy.

Arnold said he examined a picture of Spray that was sent to him by Scott Allen, a board member of the Hall of Fame. Spray's fish was reportedly 63½ inches and weighed 69 pounds, 11 ounces. The Hall of Fame recognizes records by weight, but critics of Spray's fish say photo analysis indicates it was much shorter than 63 inches, perhaps even 10 inches shorter.

That would mean the fish would likely fall short of the weight that Spray claimed.

Arnold said the riddle is matter of perspective, a fact he explains at his Web site, www.ima.umn.edu/~arnold/muskie/.

He said it's impossible to determine the true size of the fish from photos without knowing some important facts, such as how far the camera was from Spray's fish and what type of lens was used. Arnold said a phenomenon known as "projective geometry" distorts the size of the fish, depending upon how far the camera is from it.

Projective geometry is a fancy name for a well-known fact among anglers: The closer the photographer is to the fish, the bigger the fish will appear in a photo.

Without knowing the position of the camera, Arnold said, it's only guesswork as to the true size of Spray's fish.

But Arnold said the maximum length of Spray's muskie could be determined by using simple proportion. Given that Spray was 6 feet tall (72 inches), Arnold said the fish's maximum size appears to be 63 inches, as it appears in the photo next to the angler.

But that would only be the "most optimistic" view, because Spray is holding the fish in front and away from him in the picture.

"Thus, the only conclusion we can draw with certainty is the fish is shorter than 63 inches, perhaps considerably so,'' Arnold reports.

Arnold demonstrates his case on his Web site by holding a 48-inch board in the same manner that Spray holds his world-record muskie. Arnold shows how the board appears much larger than it actually is. Arnold is 2 inches shorter than Spray.

Emmett Brown Jr., executive director of the Hall of Fame, based in Hayward, Wis., said he hadn't read Arnold's report and couldn't comment on it.

He said the Hall of Fame would make a decision on Spray's fish early next year.

Arnold, who lives in Plymouth and likes to fly fish for bass and northern pike, wouldn't speculate how big Spray's fish was. "But if were in an office pool, I wouldn't bet it was 63 inches," he said.

For a man who knows his odds, that's saying a lot.

Chris Niskanen can be reached at cniskanen@pioneerpress.com or 651-228-5524.