Naturespeak A naturalist's view of the world

May 6, 2008

A Face Only a Mother Could Love

Filed under: Uncategorized — wykes @ 7:02 am

  My earlier entry regarding my day out on the Detroit River focused on the sturgeon work aboard the U.S.F.W.S. research boat Sentinel. This was the main reason for the trip – the headline material, so to speak. Our trip out into the mid-section of the stream brought us in contact with many other sights worth noting, however, and I’d like to bring a few of these to your attention as well.  First, allow me to complete a few “left over” sturgeon observations.

  The water was still quite cold this time of year. The temperature hovered around 52 degrees Fahrenheit when measured at each of the sturgeon sets. I asked Dr. Manny if there was any indication that the sturgeons were spawning yet and he shook his head in negative response. “No. it’s still a little too cold, but it’s getting there,” he answered. “The suckers are starting to spawn, though, and that means the time is getting close.” By suckers, he meant fish like the Golden Redhorse Sucker and White Sucker and was not referring to “those suckers” – as in sturgeon. You must be careful about this fisheries language where a big sucker is literally a big Sucker and a female walleye with eggs is called a hen.

  A large man made rock reef was recently laid on the bottom of the river just off the east shore of Belle Isle – at the head of the river. Scientists such as Bruce are eagerly awaiting the advent of this years breeding season to see if any sturgeon will make use of this area to lay eggs. The fish are regularly spawning on the Canadian side of the river, but need some help in returning to old sites closer to the Michigan shore.

  Out on the boat, I looked closely at one of our captured fish and suggested that she might try out this new spawning site. Her expression was unreadable, however (Here, take a look for yourself). Sturgeons don’t have ears, but do have four extremely sensitive barbels on their snout. I was hoping these appendages might pick up some sense of my message just like they sense food items on the bottom.  After all, I told her, there were plenty of other critters doing the “spring thing” out here on the river and it was time to get going.

  We passed an active Bald Eagle nest about mid-way down on the east side of Fighting Island. An adult bird was standing on the edge of the nest next to a large chick (see here).  There are at least four active nests on the Detroit this year and eagles are a regular and year-round sight.

  Down at the south end of the island there was a large Ring-billed Gull colony extending for hundreds of feet along the high bank from the top of the grassy ridge down to the limestone rubble rock (see here and here). It looked like most of the birds were sitting on eggs while the rest were flying overhead in all directions. Even though the whole place looked chaotic, there was some order within the apparent dis-order since each nest was located within a beak’s reach away from the nearest neighbor. From a distance you could hear the constant cackle of the noisy birds drift over the water as we worked the third set.

  While drifting opposite the gull colony, we pulled up a thieving Mudpuppy on one of the hooks. A series of a dozen empty hooks betrayed the presence of this giant aquatic salamander who had obviously helped himself to the feast. His last bite proved that there was no such thing as a free meal and he ended up getting snagged through the lip.

  I unhooked this wriggling beast and held him out for a portrait before tossing him back (see above and here). If the puppy looks uncomfortable, he was.  Being one of the slimiest creatures on earth (surpassing even the sturgeon in this regard) it was all I could do to keep a grip with one hand while taking a photo with the other. I was almost squeezing his innards out in order to maintain a grip. It was like holding a rotten pickle – a moving rotten pickle.   

  You are in the presence of true ugliness when you are staring at the face of a mudpuppy. Michigan’s largest salamander has a mug that only a mother could love. The large red feathery gills coming out of each side of the head only add to the unworldly nature of this beast. I wanted to get an angle that showed off the wide fin-like tail, but the thing protested so much that I was finally forced to let it drop back into the chilly depths. It was time to get back to helping Jim and Bruce with the sturgeon work, anyway.

  My left glove was covered with the snotty slime residue from my recent captive.  There was so much, as a matter of fact, that it created filmy webs between my fingers when I spread them out. The webs would dissolve into sheety dollops of goo and peel off in the wind.  Yes, admiring snotty slime from a rotten pickle was all part of a great day on the Dee-troit.

May 3, 2008

A Sturgeon in Time

Filed under: Uncategorized — wykes @ 10:04 pm

 

I just completed my third shift as a crew member aboard the good ship Sentinal and I enjoyed every minute of it.  Well, alright, not every single minute – there was the time when an extreme series of waves brought the starboard gunwale within inches of the water surface. As a landlubber I was a tiny bit horrified by this, but it was of no consequence to my shipmates Dr. Bruce Manny and Jim McFee. Bruce and Jim are fisheries biologists working with the U.S. Fish and Wildlife Service on a sturgeon monitoring program. The waves, as a matter of fact, were caused by our own wake as Bruce veered toward an orange buoy off of West Hennipen Point.

  On this particular day, the Detroit River around Fighting Island and the northern end of Grosse Ile was calm and only slightly cool. The buoy marked the southern anchoring point of a 250 foot trot line positioned to catch Lake Sturgeon from near the hard clay bottom.  On this particular pull, we ended up getting two of these magnificent fish on the line. The first was 4.2 feet long and weighed 26.4 pounds and the second was slightly longer and four pounds heavier. Both were measured, weighed and tagged before being released back into the cold emerald green water. By general fish standards these would be considered behemoths but by sturgeon standards they were completely average.

  Allow me to back up a moment and explain a few things. You may remember, if you are a regular reader, that I’ve taken you out on this trip before. If so, feel free to ignore the following details. Every year for the past few years, the USFWS crew has been out catching and tagging sturgeon on the big Detroit. They are monitoring the population and trying to build up a data base of information so that they can understand what makes this ancient fish tick. To catch these bottom feeders, the biologists put out six set lines each about 30 feet deep and equipped with 25 huge baited hooks spaced at 10 foot intervals. The bait consists of Round Gobies, those alien invaders who are abundantly available for just such a purpose. “This is the best use I can think of for these fish,” blurts out Dr. Manny. I agree with him. We both see the poetic justice of using a pesky alien to help out a rare native.

  The procedure is to hook the set line buoy, pull up the double pronged anchor, and slowly pull the line onto the deck. Each hook is detached from the line via a metal spring hook. It was my primary job to grab these hook-lines as they were pulled and keep them in a neat row along the edge of a big blue plastic barrel (here’s my work – nice eh?). When Jim returned the line to the water – after assuring the hooks are sufficiently baited – I handed them back to him one by one.  When a sturgeon came up on one of the hooks, of course, the real work began.

  We pulled up a total of six sturgeons- one each on the first two sets, and two each on the last two sets.  Each time the documentation procedure was the same. I was able to get a better view than previous trips because I was part of the process. 

  The first order of business is to lift the fish into a net cradle and weigh it. During this time, Bruce is writing down the numbers as Jim calls them out. “15.5” indicates a weight of 15 and a half kilograms. There are 2.2 pounds per kg, if you want to do the math. Our weights ranged between 6 ½ and 37 pounds. The total length was taken in millimeters from the tip of the snout to the tip of the upper lobe of the shark-like tail (which translated to a range from 35 inches to 55 inches). A shorter fork length is taken from the snout to the inside of the tail notch and then a “commercial” length from the back of the gill opening to the back of the anal fin. The girth was measured just behind the pectoral fins and ran from a mere 12 inches up to 22 inches.

  A uniquely numbered six digit tag called a Floy tag is inserted into the trailing edge of the dorsal fin – the small triangular fin just ahead of the tail. Accompanied by slight gristly sound, the tag is punctured through (with what looks to be a carpet needle!) and secured like a zip tag (see here). A radio tag, the size of a small pill, is then carefully inserted just behind the first back scute using a hollow syringe. The needle tip is daubed with a dollop of anti-biotic to make sure the small puncture heals properly.

  I thought my role significant when I was given the charge of reading off the frequency code that was called up on the hand held reader when it was passed over the post-implanted fish.  I enunciated every digit with professional clarity so that Dr. Manny could record it properly. I later found out that he already had these numbers on his sheets, having passed the reader over the electronic pills before they were inserted. My dramatic reading served only to confirm what was already known, but what the hey.

  The last part of the process involved cutting off the first spine of the left pectoral fin. By using a hack saw and a honking big knife, Jim was able to remove this 3 inch piece of fin with a minimum of blood. I will admit that the sound of saw rasping on hard cartilage does create a wince effect. This portion will be microscopically examined in the lab for a count of the annual rings that will provide an accurate age estimate. The severed spine is sealed into a small envelope upon which all the individual fish data is recorded (see here – note the super long number on the bottom line that I was responsible for reading).

  We slipped each fish back into the water within a few minutes of its capture – holding it captive on the steel deck only long enough to reap a harvest of valuable data from it.  Jim would gently lower the beast into the water and hold on for a while until it recovered sufficiently for release. Sometimes this took a minute or two, while other times the victimized fish broke free as soon as it hit the water.

  After the last set was complete, the Sentinel returned to the Wyandotte municipal dock and the gear was hauled ashore. We talked about the success of the day and the promise offered by the following morning.

  “You shoulda seen the fish we caught last week,” said Bruce when I expressed amazement at the 37 pounder. “That fish was so heavy,” he delivered like a set up line, “that it exceeded the capacity of our scale.” I glanced down at the scale to see that it was a 50 kg. unit, so I figured out and verbalized that it was over 110 pounds.  “Well over,” he added. “The snout hung out about this far over the front of the sling,” he said holding his hands about 18 inches apart, “and the tail hung out the same distance out the back. The girth was something like a meter.”  Given these dimensions, this sturgeon was one of those old school giants in the six foot plus category. Unfortunately Jim forgot his camera on that day, so the fish remains only as a statistical record.

“Sure,” I said in mock disbelief. “No picture, eh?”  “No, really,” they both retorted. Given the absence of eye winks, I was force to believe what they said was actually the truth.

  The potential of pulling up another one of these giants, or even re-capturing last week’s animal, will keep me coming back to the sturgeon boat year after year.

  Although the big fish are always the primary thrill, the other sights along the big river were satisfying as well. I’ll introduce a few of these in the next installment.

May 1, 2008

Worms for Lunch

Filed under: Uncategorized — wykes @ 4:41 pm

Today, while eating my lunch, I was given over to pondering a question. I’ve always known that the early bird gets the worm (I mean, it’s a fact of life right?), but how is it that the late bird also gets the worm?   You see, birds – especially those of the robin ilk – need to eat morning, noon, and evening and can’t afford to stop at the early worm.  They engage in worm hunting throughout the mid day, when the worms themselves aren’t active, and yet they still are successful.

  It is not my current intention to go in-depth into the subject of how robins find worms.  I do not know the whole answer, nor does anyone else apparently. Type the phrase “how robins find worms” into your search engine and you’ll come up with some conflicting answers. That they see ‘em is the primary answer, but the jury is out as to whether they hear ‘em as well. You’ve seen the birds perform the ritual a million times: a quick head down run ending in an erect pose, a pause followed by a tilt of the head, a jab or two, and up comes a worm held firmly in the beak.

  As a creature with oppositely facing eyes, the robin has to tilt its head sideways in order to get a vision fix on a close object such as a worm. It has little binocular vision capability and must rely on the high resolution sharpness provided by a single eye for detail work. This head tilt has also been construed to mean that the bird is directing an ear opening toward the ground and using sensitive hearing abilities to pinpoint prey location. There has been at least one experiment that seems to bear this out this latter theory. In that situation a robin was able to locate some mealworms without any visual clues. 

  Earthworms are covered with fine bristles and they do make somewhat of a quiet racket when pushing up against dry leaves.  It is entirely possible that the keen-eared robin is capable of hearing these sounds, but the head tilt is definitely a vision related posture.  The overall answer is probably a combination of visual clues and auditory clues. Either way, the worm is history.

  My lunchtime question was prompted by an opportunity to watch a robin work the bark chip mulch around some shadbush plantings. I was taking a break from presenting a whole slew of nature programs as part of the annual River Rouge Water Festival on the campus of the University of Michigan at Dearborn. My lunch break was 25 minutes long, so I had the time to sit outside on a picnic table while consuming my complimentary turkey wrap (I only do this program because of the free food). 

   Apart from watching the masses of 4th and 5th graders and their befuddled teacher escorts walk across campus, my attention was drawn to a single male robin about ten feet in front of me. I fixed my gaze upon the fowl as a way to occupy my time. At first I perceived this activity akin to being forced to read a copy of Redbook magazine in the doctor’s waiting room because all the Outdoor Life mags are gone, but this view soon changed.

  This bird seemed to be having extraordinary luck.  He kept returning to a patch near the base of one of the plantings. With each bite of my wrap, this efficient hunter was downing a worm – about one every ten seconds for a short period. Usually it took a few side swipes of the beak to clear away a piece of bark before the prize was secured. I watched the ground in front of him very closely to see if I could detect any worm motion but was unsuccessful. The robin flew off each time a passing clan of noisy children walked by, but it invariably returned to the same spot.

  It was a cool dry day and I couldn’t imagine why a bunch of worms would expose themselves in the noon hour sun – especially in the presence of killer. There were none in the bark closest to me.  I discovered the secret about the time I was tearing into my huge Macadamia nut cookie and confirmed it by the time I ripped into a bag of Doritos (I told you the free food was crucial here). The robin had an underground partner.

  Every now and then, a section of bark would push up from the ground at the exact point where the bird was operating. A mole was working the soil beneath the bark layer and causing the worms to issue up out of the ground as if they were being electrocuted.  The mole never broke the surface. I can’t confirm that the robin knew what was going on, but then again, I don’t think he cared. There were lots of worms and that’s all that mattered.

  I’ve seen this mole-induced worm terror before. Since earthworms are very sensitive to ground vibrations, the digging action of a mole – a worm predator- will alert a vibratory sense within all worms in the immediate vicinity to seek the safety of the surface. The escaping worms look like they are jumping out of a fire. Once I followed the course of a tunneling mole for several feet by watching the fleeing horde of worms that surfaced just ahead of it.

  Worm hunters – human worm hunters that is – have long employed this trick to get worms up and out. By sticking a rod into the ground and tapping it lightly, they imitate the mole’s digging sounds and fill up their bait containers in no time.

  Today was the first time that I saw a non-human bait collector take advantage of this effect. I enjoyed this bit of unexpected dinner theatre. It goes to prove that even mundane observations can reap some reward. One has to feel a little bit sorry for the worms in this case. Normally the surface provides them temporary safety until the danger passes. But when sandwiched between two predators, well, it’s like jumping from the frying pan in to the fire.  Fried worms anyone?

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