Smelt Research on Moosehead Lake

By Fisheries Biologist Tim Obrey The Moosehead Lake Region, as designated by the Maine Department of Inland Fisheries and Wildlife, is big…some might say wicked big.  It stretches from Dover-Foxcroft in the south to Allagash Lake in the north, Rainbow Lake to the east and the thriving metropolis of Skinner to the west. The land area covers 4,391 square miles with 4,125 miles of flowing water and over a quarter million acres of Great Ponds (there’s also another 2,160 acres of not so Great Ponds. i.e. less than 10 acres).   We have a total of three permanent staff members to manage the outstanding fisheries resources in this vast region. We’re fortunate to have the ability to hire college interns to help out from time to time too. The reality is we spend a lot of our time on this 75,000-acre puddle that sits at our doorstep: Moosehead Lake.  It is Maine’s largest lake and surely one of the most beautiful anywhere.  The fisheries are complex with interactions between all three major gamefish and the assortment of baitfish and other species.  There are projects that we must complete every year to monitor the fishery.  Some of these tasks have been completed annually for decades.  But we also can develop new studies. Some of these have direct management implications and others are just interesting projects that help better understand the ecology of this big lake. One of our annual tasks is winter creel surveys. I’m often asked by young budding wannabe biologists if I get to fish all day as part of my duties. Well…no. We’re kind of busy from 8am to 5pm…see above paragraph. But the next best thing is to fish vicariously by working in the field and talking to anglers. In the winter, we hit the ice with our snowmobiles on the weekends gathering data on angler catch rates. We also measure all the gamefish we see to monitor growth. We routinely take stomach samples to determine the abundance of smelt (forage) in the lake. We have been able to develop specific mathematical target objectives for many of our goals. The good news is, Moosehead Lake is in great shape. We are meeting or exceeding nearly all of our goals. Anglers are catching more fish and bigger fish. Recently, we began work on a new project that we hope will shed some light on the biology of smelt. This work is not just relevant to Moosehead Lake, but could be useful for other big lakes in Maine.  The concept was to develop a study to provide an index of abundance for young smelt and to help understand the natural variation that often occurs in smelt populations.  There have been a few studies that indicate young newly hatched smelt can be subject to high mortality if the correct food source (plankton) is not present during their initial two-week window after hatching and dropping out of the stream. This past spring, we hired recent Unity College graduate Maddie Killian to conduct much of the field and lab work.  Our study site is located at the mouth of Lily Bay Brook. We make several 20 minute sets with a plankton net at the time smelt are hatching. We count the smelt fry and extrapolate the catch to get an estimate for each day. This continues for the duration of the hatch which is about two to three weeks. In 2017, we estimated just over 9 million smelt hatched from this small brook. In 2018, the estimate was closer to 7 million. These numbers are actually pretty close. It will be interesting to continue the work for several more years to look at the range in estimates. Soon after the hatching ends, we are on the lake collecting plankton samples in Lily Bay. Then the fun begins…staring deep into a microscope to identify and count plankton. This requires a fair amount of lab time…and caffeine.  I’d rather be fishing.  But we had good success this year collecting and processing our samples. Later in the summer we take our plankton net back to the water. This time we tow the net behind the boat at night capturing young smelt on the surface of the lake in Lily Bay. At some point in the future, we will know what a “normal” range is for young smelt hatching in Lily Bay Brook. If we find a year that is way below the average, then we know there may be growth problems for our gamefish in the coming year. We also want to know the range for plankton abundance.  There is nothing we can do to change plankton abundance since it is totally related to water quality and water temperatures.  But if we detect a significant decline, we can assume smelt will have a higher mortality that year. Finally, we hope to combine the information from the summer smelt tows with the plankton abundance, and the spring hatch numbers to detect any changes in abundance that could be related to lack of food.  If we determine that the smelt are in low abundance, we could possibly reduce our salmon stocking to protect the growth of our gamefish.  Or if everything is peachy, we could increase our stocking to improve the catch while maintaining the good growth rates. There are many, many projects that we work on routinely on Moosehead Lake, some of which include: winter creel surveys, summer creel surveys, angler counts for use estimates, summer gillnetting, smelt run evaluations, fall trapnetting, Roach River weir, East Outlet fishway trap, Moose River rotary screw trap (next summer), radio telemetry studies, and voluntary creel survey boxes on the East and West Outlets.  We want to thank the Natural Resource Education Center at Moosehead and the Moosehead Lake Fisheries Coalition.  These local nonprofits have donated funds for us to purchase equipment and hire interns to complete these tasks.  It’s great to have partners that share our commitment for making this lake the best it can be and for all to enjoy.