Naturespeak A naturalist's view of the world

April 5, 2007

It Ain’t Over ‘Til the Fat Sturgeon Sings

Filed under: Uncategorized — wykes @ 11:30 pm

April 4, 2007

  In the pre-dawn darkness, Jim Boase and his assistant get the “Serindipity” ready for launching into the Detroit River. The initial rays of the rising sun illuminated the scene as the men transferred equipment to the 35 ft. aluminum vessel from their truck. There were several crates of supplies, a barrel rimmed with large hooks, a huge net, and several coolers.  Two 100 horsepower Johnsons, an impressive lifting crane, and dramatically sweeping sides sets their boat apart from the others there at the municipal ramp. It promised to be a pleasant April day with temperatures already in the 40’s.

  Bleary eyed Walleye fishermen sipped coffee and watched the procedure while anxiously waiting their turn on the ramp.  Just north of the launch site, a dozen of their brethren were already clustered over a hot spot out on the gray waters, and no doubt were catching their limit.  

  It became apparent that the “Serendipity” crew didn’t represent one of the “locals” as they donned day glow orange survival suits with large white “U.S. Fish & Wildlife Service” letters on the back. This fishing trip was part of a research project to monitor the Sturgeon and Walleye populations of the Detroit River.  They just started last week and will continue their work throughout the April/May spawning season.

 Michigan DNR Fisheries biologist Jeff Braunscheidel was along for the ride as well. Jeff was there to check out a few locations on the river to place monitoring nets.  The DNR wants to assess fish mortality from the upcoming walleye tournaments.  Me? Well, I was there as a volunteer crew member to assist them as best I could.  Actually, I have to admit, I was there primarily to see a live Detroit River sturgeon and jumped at the chance to be with the crew.  Fortunately, they had an extra day-glow survival suit for me so I could both act and look the part of researcher while fulfilling my selfish desire.

  As we headed out, the roar of the twin engines lifted the bow and sent the craft flying downstream. Jim explained the situation to me as best he could – overcoming the noise and my continual exclamations of “What?”  First, we would be visiting four gillnet sets for walleye.  Later we’d be checking out the set lines for sturgeon.  They hauled in 27 of the giant fish last week and were expecting more of the same today. That news lifted my expectations even further.

  The location of the first gill net set-up was marked with a set of bright orange buoys topped off with a flag.   The vessel pulled along side the buoy, Jim snagged the line with a boat hook, and brought it over the rail.  Seconds later a large “v” shaped Sebawing anchor swung into view and was carefully hauled out and hooked onto the gunwale by Jeff.  Soon after, Jim and I grabbed hold of the net and started to haul the 125 foot length out onto the deck. 

  After a dozen feet of empty mesh was pulled, one walleye appeared out of the depths – ensnared in its tangles.  Jeff started to pull the fish out, when another appeared, then another.  Pretty soon, it appeared that every square inch was full of fat walleyes and the burden of fish became heavy. 

  I dropped the line and assisted Jeff with fish removal.  After the entire net length was on the deck, all hands were busy extricating the catch. This wasn’t an easy task. Gill nets consist of fine threads that wrap the body and catch in the gill flaps, upper jaw and behind fins.  Each panel of the net had a different sized weave in order to sample different size fish, although a good number were trapped in the 2 ½ inch mesh.

  Since the goal was to keep the fish and not release them, we didn’t need to rush things.  After what seemed like an eternity, I proudly pulled one 18 incher free and tossed it into a five gallon bucket. The other guys had already filled the bucket by that time, so I accelerated the pace. 

  Overall there were probably 35 fish in that haul. Not a one of them was small and all of them were fertile males in spawning condition – very fertile (spilling out with fertility, if you get my drift, so that we and the deck were a slimy mess.)

  We pulled out several hooks, a crayfish, countless algae clumps, and untangled knots before easing the net back into the river. Jim threw the anchor back as the line tightened.  I admired the catch as the buoy was plunked back into position.  Walleye are impressive fish with sizable teeth, a pale “walled” eye, greenish speckled body and a distinctive tail fin with the lower lobe tipped in white.  Jim explained that they would be later be measured, weighted, and aged to provide valuable data on the health of the walleye population. 

  This procedure was repeated at three other locations on the river, although the results were not as dramatic as the first haul.  I think we took in 50 some fish, but no one was counting – there would be plenty of time for that back in the lab.  At least one 6 pound female walleye (a “hen” as they called it) was taken, along with a handful of stunningly yellow Perch, and a Silver Lamprey attached to one of the Walleyes. The lamprey released its suction grip on its quarry upon clearing the gunwale and slithered over the deck seeking refuge among the buckets.  I kept the native parasite as a specimen for later examination in my lab.  The truly interesting specimens, however, were due up next. As we entered the sturgeon grounds around Fighting Island, anticipation filled the air.

  The anchor and buoy set-up was similar to that on the gill nets, but the rig consisted of a single trot line with large baited hooks set at about ten foot intervals.  The 24 hooks, alternating between 2 inches and 1 ½ inch in length, were attached to short lines snapped onto the line.  The line lay close to the bottom where the fish habitually fed.

  I was to discover that the bait consisted of Round Gobies and chunks of salted fish. It was my job to re-bait the hooks as they were un-snapped and handed to me.  The first hook, a large one, got a goby attached. The next hook was to be a small one and also received a goby.  The next large hook got a chunk of cut bait and the next one after that was a little one baited with cut bait.  This alternating pattern insured a wide variety of size and bait options to entice the sturgeon.

  One by one the hooks cleared the water and Jim announced “small hook, empty….large hook, empty….small hook, empty…”  I kept up the baiting process and carefully spaced the finished sets around the rim of a large blue barrel.

  “Small hook, empty….large hook, empty….small hook, empty…,” was the repeated call from Jim.  It looked like the first line would be completely devoid of a catch until the call came out: “Large hook, mudpuppy.”  The indignant amphibian wiggled about wildly upon the entering the sky world.  Several more mudpuppies, or waterdogs as they are known, were hauled in, but no sturgeon.  “We’ll do better on the next one,” Jim apologized as if it were his fault. The freshly (albeit poorly baited) hooks were snapped back into place and the set was eased back into the deep as the boat was expertly backed up. 

   The next set yielded more empty hooks and frustrated mudpuppies, so it was with more than a little apprehension that we approached the third – and last set.  The third one proved to be a charm. Just as soon as Jim tugged on the rope, he could tell there was something there.  “We’ve got one, “he crowed and commenced pulling line.  After ten or so empty hooks, the eleventh cleared the surface with a magnificent sturgeon attached.

  Jeff scrambled for the net as Jim’s partner put the boat in idle. All leaned over the left side of the boat to gather the fish in.  Quickly sliding a chunk of cut bait onto a hook (I was getting pretty good at this by now), I stood up to admire the catch.

  Spilling out onto the deck, a pale brown monster laid passively on the deck.  Its long upturned nose, large sucking mouth, smooth leathery skin, and five rows of bony plates gave it a distinctively primitive appearance – earned after a lengthy occupation of the earth predating the dinosaurs.  The tail is also upturned and shark like. This type of tail is termed “hetertocercal,” but “fascinating” is a more suitable term.

 The men gently lifted the fish and cradled it into a dip net propped across the gunwales. Time was of the essence. The necessary data had to be gathered quickly so the sturgeon could be returned to his lair with minimal stress.

  One by one, the measurements were taken and called out as Jim recorded the information.  “Total length – 1232 mm” (about 4 feet), “Fork length 1097 mm” (that’s the measurement from tip of nose to the inside of the fork in the tail), “Commercial Length, 694 mm” (2.2 feet – the measure from the back of the gill plate to the back of the dorsal – or tip – fin). “Girth, 432 mm” (17”).  Hooking the net to a large scale, the men lifted the creature up, studied the scale and called out “Weight, 9.3 kg.” and lowered it gently down.  This sturgeon was small by sturgeon standards, being only 20 ½ pounds. Some members of its kind tip the scale at nearly 300 lbs and reach lengths of over7 feet.

  A heavy fin ray was clipped off the left front “pectoral fin” (the one right behind the gills) and placed into a bag.  This would be used to age the fish and run genetic analysis.  The growth rings in the ray cartilage are a record of growth years – it seems that sturgeon can’t lie about their age.  The big ones are known to have survived over 150 years.  This one was probably closer to 25 years in age, but only her hair dresser knows for sure! Actually, the question of whether it was a “he” or “she” couldn’t be immediately determined, so I secretly dubbed it Pat – just to be safe.

  The last two procedures before release were the insertion of an external orange Floy tag at the base of the dorsal fin, and a PIT (Passive Integrated Transponder) tag injected just under the skin.  The PIT tag emitted a unique frequency that would track the fish through out the rest of its long life.  The guys passed the receiver over the inserted tag to see if it was working properly, and gingerly lowered the fish back into the water.

  Entering back into its element, the giant drifted for a short while before kicking back into action and diving into the depths. It was now on the record books as an individual that could be tracked and monitored.  Once nearly fished to extinction and victimized by pollution, the gentle giants are staging a comeback. By following “Pat’s” future life in the Detroit River, scientists can learn more about what makes the Great Lakes Sturgeon tick and help it on its road to recovery. 

  The rest of the line was empty, by the way, and we had to be satisfied with just one sturgeon for the day.  As we returned back to the dock in the glare of the mid-day sun, I felt satisfied.  Jim and his crew mate will return tomorrow to repeat the routine of today.  It is apparent that this is far from “routine” for them.  I now know at least one sturgeon that lurks beneath these waters, while they will know dozens by the time the season ends.   

  It is comforting for us to know that there is at least one magnificent being out there that very likely will outlive us all.

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