Thursday, April 28, 2011
Paddlefish are one of my favorite species, but there is one in particular that may be my favorite fish of all time.
This shark-like looking fish was implanted with a transmitter six years ago. Then, this paddlefish, or spoonbill, somehow lost his paddle! The accident didn’t seem to hamper his ability to swim—he traveled more than 700 miles in one year.
That brings up the question, just what is that paddle on the paddlefish used for?
In the early 1900’s, the paddle or rostrum was thought by scientists to be a shovel used for digging up mud and silt as the fish searched for small organisms to eat.
But the paddle is not a shovel, a scoop, or a spear. If you look closely at the paddle you will notice that it has no scratches on it. Besides we know that paddlefish are mid-water filter feeders and are not feeding off the bottom.
We do know that the paddle and head are covered with thousands of tiny sensory pores capable of detecting minute electrical charges associated with zooplankton, the major food source of paddlefish. These are the same sensory pores that can detect objects in muddy water.
The paddle also appears to function as a rudder, providing lift, allowing the fish to open its mouth wide for filter feeding without being dragged to the bottom. When feeding, adult paddlefish swim with their mouths wide open and filter the zooplankton from the water with filament-like gill rakers. This filter-feeding strategy is why paddlefish do not take bait and why instead anglers must snag them.
It’s amazing that the largest of Montana’s state record paddlefish, a whopping 142 lbs, feeds on such small organisms. It takes a long time to grow to that size—paddlefish have been aged at over 50 years.
There are two populations of this fish in Montana: the Sakakawea population, which spends most of its life in Lake Sakakawea with spawning migrations into the Yellowstone, Missouri, and Milk rivers in Montana; and the Fort Peck population, which spends most of its life in Fort Peck Reservoir and migrate up the Missouri River to spawn. Males spawn every one to two years and females spawn every two to four years.
Paddlefish are good table fare; however, you can expect to take home only 15-20 percent of the fish’s weight when trimmed properly. The roe from the females is sold for approximately$25 an ounce as caviar.
We are very fortunate to have this prehistoric critter still living in Montana. There is only one other species of paddlefish in the world. It lives in the Yangtze River in China.