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The Amazingly Adaptable Whitefish
“Life, uh, finds a way.”

Harbor Angler Report, February 16th Photo

 

I have recently been watching a fascinating nature series, “Seven Worlds, One Planet”. It is a BBC produced series being broadcast on BBC America and available locally on the AMC Network via satellite or streaming services. Each episode explores one of the seven continents and highlights several animal species and their struggles to survive. The photography and the action they capture are spectacular. I highly recommend that you check out Seven Worlds, One Planet if you have the opportunity. One particular segment of the North America episode caught my attention. It dealt with polar bears in the Arctic around Hudson Bay. As most of you know, these bears are endangered by the loss of sea ice in the Arctic due to the warming of the polar regions. Over the millennium, polar bears have adapted a feeding technique where they hunt seals on the pack ice. They stalk seals on the ice surface by waiting patiently at the seal’s air holes, attacking them when they inevitably come up for a breath. This strategy is critical because in the open ocean, seals could simply outswim the bears. Seals are the major food source for polar bears and without the ability to prey on seals, the polar bears survival is in jeopardy. With the warming of the planet, the Arctic region has formed and maintained less and less sea ice each season. With less pack ice available for polar bears to hunt on, many groups of bears cannot find sufficient food and are dying out or failing to produce offspring. There is one small group of polar bears on Hudson Bay that has found an alternate prey that may be the key to their ultimate survival, beluga whales. Beluga whales are big animals, measuring up to eighteen feet long and coming in at up to three and a half tons. The typical polar bear is less than 1500 pounds. In addition, beluga whales are deep ocean species capable of diving several thousand feet. So how does a single polar bear capture and subdue a beluga whale? Well, you gotta watch the video. It is amazing. In short, there are times when the belugas come into shallow water to feed. The bears will perch themselves on a rock outcrop and patiently wait for an unsuspecting beluga to swim close enough for them to pounce. They are often unsuccessful, but when they score, everyone eats! What amazed me about this story was the incredible ability of these animals to adapt. With their main food source being taken away by a changing environment, these animals have figured out a way to survive. Sure, polar bears have always preyed on the occasional beached beluga or captured them at air holes, but now, at least for this group of bears, belugas have become a major food source.  As mathematician Ian Malcolm so eloquently declares in the movie Jurassic Park, "Life, uh, finds a way". This is a truly remarkable example of nature doing what it has to do to survive.

We have an equally amazing animal in the waters surrounding Door County, the Lake Whitefish (Coregonus clupeaformis), that has incredibly adapted to the loss of its major food source by learning to feed on something totally different. Whitefish have been in Lake Michigan probably as long as there has been a Lake Michigan, at least for thousands of years. In that time, the species has evolved to feed on the most readily available food source in the lake, very tiny phytoplankton and zooplankton, primarily a small shrimp-like creature called a Diporeia or “scud”. These minuscule  amphipods (less than ½ inch long) inhabited the lake bottom in great numbers. In order to successfully feed on these creatures Lake Whitefish adopted a benthic (deep-water) lifestyle and their mouth structure and digestive system evolved to efficiently harvest and consume the Diporeia. These adaptations allowed the whitefish and other related species to thrive in the relatively sterile waters of Lake Michigan and Lake Superior. This predator-prey relationship worked fine until new variables were introduced into the system, namely numerous invasive species. One group of invasives, non-native mussels, had a particularly devastating effect on the whitefish-Diporeia relationship. Zebra mussels and their larger relative the Quagga mussel, feed on the same food in the detritus of the lake bottom that the Diporeia do, only much, much better. With the massive influx of the mussels in the last several decades, the food source of the Diporeia has rapidly declined and with it the number of the amphipods has plummeted.  So much so that the whitefish can no longer depend on Diporeia as their sustaining food source. What’s a fish to do? Adapt. And that’s what the whitefish has done. Just like the polar bears, whitefish went out and found another prey that they could tackle, if only just barley (pun intended). While the whitefish were mucking around on the lake bottom searching for the increasingly scarce scuds, they kept bumping into another invasive species recently introduced into the lake, the Round Goby. Gobys are slimy little buggers that are always on the bottom as a result of them not possessing a swim bladder. One can easily imagine a whitefish “accidently” sucking in a small goby and finding it tasty, or at least nutritious. If you have ever studied the small, delicate, downturned mouth of a whitefish, you will see that it is not the best instrument for capturing fish. But, life found a way. Whitefish learned to pin the gobys to the lake bottom and suck them up. I have actually seen this behavior on an underwater camera. In an incredible short period of time, less than 10 years, large numbers of whitefish have adapted to feed on the round gobys to the point that they have now become a major food source. The whitefish also had to change where they search for food. Since large number of gobys thrive in shallow water, the whitefish have had to move into the shallow water to feed on them. So here we have a species in danger of extinction that has changed from feeding on tiny creatures in deep water to feeding on 3-inch fish in shallow water. A fish that did not even exist in its environment thirty years ago. "Life, uh, finds a way". Of course, the story is more complicated than the whitefish just eating gobys to survive. What do they eat before they are big enough to swallow a goby? What other animals are competing for the gobys? How will goby behavior change to escape this predation? All good questions, but let’s get to fishing.

It did not take long for anglers to appreciate and take advantage of this change in whitefish feeding behavior. Starting about 10 to 15 years ago anglers began targeting whitefish as they came into the more accessible shallower water (less the 100 feet, sometimes as shallow as 10 feet). They developed lures and techniques that exploited the whitefish’s penchant for eating gobys. Now a days, if you want to catch whitefish in Green Bay, bounce anything that looks goby-like and smells like fish on the bottom and sooner or later a whitefish will pounce on it. Dark colored jigs, Jigging Raplas, Moonshine jigging minnows are all effective lure, especially when tipped with a piece of live minnow or Gulp bait. Whitefish still remember how to eat those little amphipods as well and anglers can use that trait to increase their chances of putting whitefish on the ice. Just add a slider rig above your jig with the hook tipped with a waxie or spike. This way you are fishing with two totally different types of baits at the same time. You are serving the whitefish a choice of entrées. A sort of whitefish small-plates offering.

I have been doing exactly that on several recent outings onto the ice of Green Bay. I have been walking off any one of the many access points north and south of Egg Harbor. Yesterday I man-hauled my sled out 300 to 400 yards off shore to about 40 FOW. There was plenty of ice, over a foot in most places. After drilling holes and setting up my portable Frabil shack, I dropped a brown jig tipped with a minnow head to the bottom. I had a slider hook situated about ten inches above the jig tipped with a fat waxie. Soon I could spot whities showing up on sonar near the bottom tracking my bait. Now there are lots of different techniques for working the bait for whitefish. You can get plenty of opinions at any bait shop or local tavern. However, all of the successful techniques involve keeping the bait near the bottom and moving it constantly. Whitefish typically will lose interest in a lure if it becomes motionless. My method involves dropping the jig right to the bottom. I then take up the slack, lift the lure one to two feet off the bottom and immediately let it drop back down, making sure the lure contacts the bottom. I lift the lure again so there is no slack and repeat. You can change things up by bouncing the jig repeated on the bottom or lifting it 4-5 feet of the bottom before dropping it back down. If you do this for fifteen or twenty minutes and don’t get hit, it is a good idea to move to a different location.

By the end of the morning I had put five whitefish on the ice and lost several others. About half of my hits came on the jig bouncing on the bottom, the others were caught on the slider hook. I took these fish  home for supper and had enough to give to my neighbors. As if to emphasize my whole point about the whitefish feeding on gobys, one of the larger whitefish disgorged a 2-inch goby while it was flopping around on the ice. As a bonus, a school of rainbow smelt, another invasive species, went swimming through and several hit the waxie on the slider rig. I ended up bringing home a few smelt, that made a delicious snack when deep fried.

So this is why Great Lakes anglers have such a love-hate relationship with many of the invasive species that are now in the lake. True, the Lake Michigan fishery is much different than any of us remember from our past. There is no going back, Pandora is out of the box. That does not mean that the fishery is doomed. The sagas of the polar bears and the lake whitefish provide a ray of hope. Given time, space and a stable environment, animals can adapt and even thrive. We as humans have to do our best to provide that stable, sustainable ecosystem. If we can find a way to accomplish that, "Life, uh, finds a way".

 

So Long, and Thanks for All the Fish, Bruce

Questions or comments to bsmith733@gmail.com