Lake Michigan kings are back — but why?

After the gloom-and-doom of 2016, anglers are gearing up for a much better run of salmon in 2017. Recent trends in the fishery suggest that ups and downs may be the new norm if prey populations do not stabilize.

Chinook salmon from the 2014 year-class are now Age 3 and they seem to be providing very good fishing in Lake Michigan.

Chinook salmon from the 2014 year-class are now Age 3 and they seem to be providing very good fishing in Lake Michigan. File photo: Michigan Sea Grant

Spread the word!  Lake Michigan kings are back — for now.

After a couple of disappointing years of fishing for Chinook salmon along the Michigan shoreline of Lake Michigan, anglers are once again excited about the late-summer bonanza that these “king” salmon provide. While the final estimates of angler harvest and catch rates will not be available from Michigan DNR and other agencies until spring, the long lines of heavy coolers at fish cleaning stations and full boards of fish are a very good sign.

The size of fish is even more impressive. Ever since bacterial kidney disease (BKD) ran through the Chinook salmon population in the late 1980s, king salmon over 30 pounds have been rare to nonexistent in most years. This year has already produced numerous 30 pounders and even one giant that tipped the scales at 41.48 pounds (see details).

Why the rebound?

While fisheries scientists do not have a definitive answer to this question, there are several factors that at work. Many relate to the poor year-class of Chinook salmon in 2013. Many anglers will remember the public process that led up to the 46 percent reduction in Chinook salmon stocking for 2013. On top of this stocking cut, natural reproduction fell by an estimated 84 percent in 2013. All told, the number of Chinook salmon entering Lake Michigan dropped from 10.68 million in 2012 to 3.5 million in 2013.

This weak 2013 year-class was a big factor in the poor fishing experienced last year because Age 3 fish from the 2013 year-class were returning to spawn in 2016. The good news is that wild reproduction increased slightly in 2014 and the total number of Chinook salmon increased to 6.47 million (stocking remained steady from 2013 to 2014).

Chinook salmon from the 2014 year-class are now Age 3 and they seem to be providing very good fishing. Fisheries managers have been trying to balance the number of predators and available prey for decades, and judging by early reports it seems that the current balance is providing a nice mix of good catch rates and large, healthy salmon. However, this does not mean that the future of the Lake Michigan fishery is secure.

Ups and downs may be the new norm

Growth of salmon has been bouncing up and down like a ping pong ball over the past decade. The growth rate of fish is a good indicator of their overall well-being and ability to find enough food, so this means that conditions are changing a lot from one year to the next.

Fisheries managers look at the weight of mature Age 3 female Chinook salmon returning to weirs and harbors as a standardized measure of salmon growth in Lake Michigan. In 2015, the average weight of an Age 3 female was 13.1 pounds. This increased to 19.0 pounds in 2016. That is a huge difference!

Such radical and rapid shifts in growth rate indicate instability in the ecosystem. In other words, food availability is changing a lot from one year to the next. Some of this is related to changes in the number of predators (especially the big fluctuations in wild Chinook salmon production) but fluctuations in the availability of alewife (the salmon’s food source) are a bigger problem.

In short, small alewife are relatively abundant in some years and provide a lot of food for salmon. In other years, alewife do not produce as many young and salmon have trouble finding food. A big problem in recent years is that alewife do not often survive to spawn several times. Instead, nearly all alewife are eaten before they reach Age 5.

Not coincidentally, the last really good alewife year class we had was in 2012. The alewife from that 2012 year-class are now Age 5. If some of them are able to avoid all of the hungry mouths out in the big lake until next year then we may finally have some Age 6 alewife in Lake Michigan once again.

This would be a good sign for overall stability of predator-prey balance in the lake, but it is by no means guaranteed. Prior to 2000, alewife of Age 6, 7, and 8 were fairly common and in some years Age 9 alewife were also found. We are still a long way from that level of stability in older alewife.

Judging by recent history, the boom times will not last long. Get out there and enjoy it while it lasts, and remember the good times next time we have a tough season.

Seafood HACCP Training Course

Event Date: 12/5/2017
End Date: 12/7/2017

A Seafood Hazard Analysis Critical Control Point (HACCP) Training Course that is being coordinated by Michigan Sea Grant, Michigan State University Extension, and the Great Lakes Indian Fish and Wildlife Commission will be held December 5-7, 2017 at Ojibwa Casino Resort in Baraga, Michigan. All fish processors are required to take this training if they are not currently certified.

Hazard Analysis Critical Control Point (HACCP) consists of identifying safety hazards, determining where they occur, monitoring these points and recording the results. HACCP involves day-to-day monitoring of critical control points by production employees. The Seafood HACCP regulation that is enforced by the U.S. Food and Drug Administration is based on the belief that commercial fish processors can understand the food safety hazards of their products and take reasonable steps to control them. Commercial fish processors are required either to obtain formal training for one or more of their own employees or to hire trained independent contractors to perform the HACCP functions.

The HACCP regulation requires processors to keep extensive records of processing and sanitation at their facilities.

Those completing the course will receive a Seafood Alliance HACCP Certificate issued through the Association of Food and Drug Officials that is recognized by agencies regulating fish processors.

For registration information please contact Ron Kinnunen at kinnune1@msu.edu

New video shows anglers how to remove stomachs for fish diet study

Researchers are trying to learn more about what trout, salmon, and walleye are eating in lakes Huron and Michigan. Anglers can help by donating stomachs from their catch.

Fisheries scientists around Lake Michigan and Lake Huron are working on a project led by Dr. Brian Roth at Michigan State University to understand what, and how much, different species of fish are eating. Invasive species such as round goby have damaged the environment, but they also provide food for some gamefish. Quagga mussels have reduced the amount of food in open water areas, but they also provide a food source for round goby.

Last year, much debate focused on alewife, an open water baitfish. This new study should provide better information regarding how many alewife are being consumed by different species including Chinook salmon, coho salmon, Atlantic salmon, lake trout, steelhead, brown trout, and walleye. Some species, such as Chinook salmon, rarely switch to other food sources. On the other hand, fish such as lake trout, brown trout, and walleye readily switch to feeding on bottom-dwelling fish like round goby. Sometimes.

This comprehensive effort will attempt to figure out when and where certain gamefish take advantage of round goby, alewife, and other food sources including invertebrates like opossum shrimp and spiny water flea. In order to get an adequate number of fish from all seasons of the year and all regions of the two lakes, scientists are hoping anglers can pitch in and contribute stomachs for the study. 

How to participate

  • Watch this short video to learn how to collect stomachs. It is very important not to bias the study by collecting only full (or only empty) stomachs.
  • If you are collecting stomachs after a fishing trip, be sure to collect ALL stomachs from each species that you are collecting.
  • It is not necessary to collect stomachs from every fishing trip you take, but stomachs from 2-3 trips per month would be very helpful.

What, when, and where to collect

  • What: Stomachs from all trout and salmon species, and walleye.
  • When: Now through the end of the 2019 fishing season.
  • Where: All waters of Lake Huron and Lake Michigan, including large bays like Saginaw Bay and Green Bay, but not including rivers or drowned rivermouth lakes.

What to focus on

Creel census clerks with Michigan DNR, biotechs funded by U.S. Fish & Wildlife Service, and US Geological Survey biologists will be working to collect stomachs at access sites and in conjunction with major fishing tournaments. Anglers can help these agencies to fill in the gaps by contributing stomachs from less-common species, early- and late-season catches, and fish caught at night or in regions that do not get as much coverage by agency personnel.

Some ideas to focus on include:

  • early-season brown trout
  • Green Bay walleye
  • all species in northern Lake Michigan from Grand Traverse Bay north to Manistique
  • mid- to late-summer salmon and trout from St. Joseph north to Saugatuck

All species from all areas of Lake Michigan and Lake Huron are appreciated, but these focus areas are particularly important because angler-submitted stomachs may make a critical difference in providing enough stomachs to meet sample size targets.

Materials for stomach collection include:

Data tags, list of freezer drop sites, video and full instructions are also available at www.michiganseagrant.org/diet.

May, June showers bring higher Great Lake water levels for summer 2017

Great Lake levels are up with Lake Ontario reaching an all-time high.

Lake Ontario reached an all-time record high in May 2017, resulting in impacts to coastal homeowners and more. High Water Event, New York. Photo: U.S. Army Corps of Engineers Public Affairs

Lake Ontario reached an all-time record high in May 2017, resulting in impacts to coastal homeowners and more. High Water Event, New York. Photo: U.S. Army Corps of Engineers Public Affairs

Have you seen the news on high lake levels on Lake Ontario? Lake Ontario reached all-time record highs in May 2017, resulting in significant coastal community, road, infrastructure and homeowner impacts. Currently the weekly Lake Ontario levels show Lake Ontario is about 30 inches higher than this time last year and 28” above the long term average in June. Colleagues with New York Sea Grant Extension are aiding in this crisis, using a scientific survey to determine impacts of the high water levels. The large rise can be attributed to very high precipitation on the basin, getting almost double the average precipitation as normal.

Back in Michigan, significant rain storms happened in late June 2017, particularly impacting the Saginaw Bay area. The United States Army Corps of Engineers estimates that Lakes Michigan-Huron rose a full 6 inches from April to May during the spring rise and had above average water supplies coming into the system. Lakes Michigan-Huron are forecast to be on the high side of average, about 15 inches above the long term average.

Lake Superior also rose about 6 inches during seasonal rise in May, being about 8 inches above the long term average and about 2” higher than in 2016. Precipitation and net basin supply was above average, with outflows above average through the St. Marys River.

Lake Erie is about 19” above its long term average and 9” above May 2016 levels and the most recent predictions are that it has reached the peak water level for 2017 and will decline about 3” over the next month.

As we head further into summer 2017, visitors to the beaches and boat launch ramps will notice these somewhat higher lake levels. Other great tools to check lake levels include the NOAA Great Lakes Environmental Research Laboratory’s  online Great Lakes Water Level Dashboard.

It is amazing to think back of just about 5 years ago to the fall/winter of 2012/2013. Lake Michigan/Huron actually reached the record low level ever recorded in January 2013, in close to 100 years of accurate measurements. The strong rebound from these record lows is unprecedented in our history of measurements.

This summer season is well upon us and it will be interesting to see if levels follow the typical pattern of seasonal decline or if strong precipitation drives them further up. No matter what, be careful in all your water access – swim with flotation devices; be extra careful at launch ramps; and enjoy the dynamic coast of these freshwater seas.

Alpena students learn while caring for island habitats of local community park

Elementary students tackle critical Great Lakes and natural resource conservation issues, enhance their community, and enjoy a little hands-on learning along the way.

Students review debris they recovered at Rotary Island

DenBleyker and students review debris they picked up at the island.

With the sun shining and just a short walk from school, a class of energetic students recently crossed the bridge over the Thunder Bay River to Rotary Island in Alpena, Mich. These third graders from Lincoln Elementary, Alpena Public Schools were on their way to finalize a series of environmental studies and stewardship projects. This field trip culminated a year-long study inspired by their teacher Tina DenBleyker, who has opened her classroom doors into the community to enhance student learning through hands-on environmental studies.

Applying creative place-based stewardship education (PBSE) strategies, DenBleyker engages students through hands-on community connections and environmental experiences. At the heart of their project was Rotary Island – which students ‘adopted’ and in doing so built a mutually benefiting relationship with their local Alpena Rotary Club. Supported through the Northeast Michigan Great Lakes Stewardship Initiative (NEMIGLSI) network, this Lincoln Elementary educator and student team connected with community and conservation partners, including the Alpena Convention and Visitors Bureau, City of Alpena, Huron Pines AmeriCorpsMichigan State University ExtensionMichigan Sea GrantNOAA Thunder Bay National Marine Sanctuaryand U.S. Fish and Wildlife Service (USFWS).

This project illustrates a great example of how PBSE strategies enhance learning and foster community connections through environmental stewardship studies; resulting in:

  • An engaging educational opportunity. Learning about life cycles is one example of a science learning goal for third grade students in Michigan; and what better way to learn about life cycles than exploring local monarch butterflies and their milkweed habitats. Reading and writing was another significant goal in this project both as students prepared for their projects and also as they reflected and wrote about their science explorations and findings. Students also gained valuable life skills working in teams, communicating with community partners, and leadership in implementing their projects.
  • Watershed studies resulting in environmental stewardship. Students are conducting litter pickups, planting native pollinator gardens, and a variety of other efforts that enhance and beautify this island and public park. For example, the students pick up litter and tally the items found while accomplishing marine debris monitoring and prevention goals promoted by the Alliance for the Great Lakes Adopt-a-Beach program and NOAA Marine Debris program. While picking up the litter, students identified issues with fishing line – addressing this issue by partnering with Michigan Sea Grant to build and install monofilament recycling bins on the Island. Finally, their monarch lifecycle studies led to learning about pollinators and an eventual partnership with USFWS to plan and plant a native pollinator garden on the island.
  • Valued community connections and contributions. Throughout the year students met and expanded their relationship with the local Alpena Rotary Club who own and manage the island. Mary Dunckel (also an MSU Extension Educator in Alpena County) provides leadership for Rotary Club, which welcomed and supports this school partnership on the island. Students learned more about the island and ways they could help when interviewing Rotarian Patrick Heraghty (Director of Community Foundation for Northeast Michigan). This partnership benefits school improvement goals and provides a community enhancement opportunity.
Alpena Elementary School students show off their completed monofilament recycling station – one of two installed on Rotary Island. Photo: Tina DenBleyker.

Alpena Elementary School students show off their completed monofilament recycling station – one of two installed on Rotary Island. Photo: Tina DenBleyker.

DenBleyker’s vision and planning for this stewardship project started last summer during the Lake Huron PBSE Summer Teacher Institute, a training sponsored by the NEMGLSI network and Sea Grant Center for Great Lakes Literacy. Here she learned about place-based stewardship education strategies; connected and traded ideas with other teachers, Great Lakes scientists and a variety of community partners; and gained resources in support of her work. DenBleyker jumped straight into PBSE programming with her students last fall with visits to the island – leveraging new partners and opportunities, navigating challenges, and celebrating successes. She shared her reflections as a new teacher getting started in PBSE during the 2017 NEMIGLSI Regional Networking Meeting. This summer she will share her experiences with new teachers as a lead teacher mentor during the very same Lake Huron PBSE Summer Teacher Institute. This year’s Institute is scheduled for August 14-18, 2017, in Alpena, and teachers interested can learn more and submit applications online. Applications are due July 27.

Michigan Sea Grant and Michigan State University Extension serve in providing leadership for the NEMIGLSI network, which is part of a larger, statewide network and partnership, the Great Lakes Stewardship Initiative (GLSI). Established in 2007 with funding from the Great Lakes Fishery Trust, the GLSI supports place-based stewardship education in schools and communities across Michigan. Partnerships are invaluable in our endeavor to support stewardship of our Great Lakes and natural resources. Through the NEMIGLSI network, and applied place-based education strategies, our educator partners are addressing critical Great Lakes issues.

Michigan Sea Grant storm project seeks to help communities prepare for future extreme storms

Mid-Michigan’s 2017 storm reminiscent of the 1986 Great Flood.

Flooded houses are shown in Bangor Township

Flooded houses are shown in Bangor Township. Photo: Kip Cronk | Michigan Sea Grant

On June 22 and 23, 2017 mid-Michigan was hit by a large rain event. The storm dropped 7.29 inches of rain in Mount Pleasant, 6 inches in Midland, and 3.08 inches in Bay City.

Pictures of damage in Bay, Isabella, Saginaw, and Midland counties show flooded roads, washed out culverts, damaged bridges, flooded homes, businesses, and flooded agricultural fields. Bay, Isabella and Midland counties were declared states of emergency allowing them to receive help from the state. The damages from this storm are as yet, unknown, but the 1986 Flood in the Saginaw Bay area caused about $500 million in damages.

Michigan Sea Grant and its partners have been working on a project to bring heightened awareness of extreme storms and to provide information to communities on preparing for such storms. While these suggestions are too late to help with this severe storm, there are actions communities might consider for the future in order to lessen the effects of extreme storms.

Preserve wetlands

One of the crucial functions of a wetland area is to hold excess water during storm events and let it go slowly, usually through evaporation or flowing down into the ground water table. Wetlands can hold a lot of water and that can mitigate storm impacts. This Michigan Department of Environmental Quality Wetlands Map Viewer helps identify wetland areas around the state­­.

Green infrastructure

Many developments are designed with hard materials that rain quickly runs off from and into rivers and combined storm sewers. One way to help mitigate the impact of extreme storms is to hold water on our properties in productive ways, sort of like wetlands. Rain gardens, bioswales (similar to rain gardens but designed to handle a larger amount of water), permeable pavers, green roofs, and green spaces are all ways that communities can help hold back water and reduce runoff. The Environmental Protection Agency offers a website with information to developing green infrastructure.

Protect floodplains

Rivers and streams can only hold so much water until the water flows over the bank and into an area’s natural floodplain. Leaving floodplains undeveloped is one way to store this water. Development in these areas removes the floodplain space and that water must go somewhere, which increases the impact elsewhere.

Properly construct culverts, bridges

During extreme storm events culverts and bridges are often damaged as they may not be large enough to withstand for the water overflow. The Michigan Department of Environmental Quality (DEQ) has a minor permit category for large culverts that require the structure to be built to several specific criteria including spanning a minimum of bankfull width.

Flood Insurance

Many people don’t realize they may need flood insurance. The Federal Emergency Management Agency provides insurance to property owners and also encourages communities to adopt floodplain management regulations.

House surrounded by water

The Saginaw Bay watershed is particularly vulnerable to storm hazards because of the region’s unique topography and land-use patterns. A complex network made up of 7,000 miles of rivers and streams, the Saginaw Bay watershed drains roughly 15 percent of the state of Michigan. This massive watershed includes both urban and agricultural lands. Because the watershed covers such a large flat area, extreme storm impacts are quickly magnified. Communities within the Saginaw Bay watershed face a major challenge in adapting to increased frequency and intensity of storm events. The website 1986flood.com shows the impact this storm had on the area and offers additional ways to prepare for extreme storms.

Having some of these infrastructure designs and practices in place may not be enough to stop the impact of a 7-inch rain event, but it could help mitigate the impacts during storm events. Michigan Sea Grant plans to continue outreach and education and will be providing webinars and a workshop in the fall of 2017 to help communities assess their coastal storm resiliency planning needs.

Michigan Sea Grant receives John D. Dingell Friend of the Refuge Award

Michigan Sea Grant representatives Steve Stewart and Mary Bohling with John D. Dingell, Jr., IWRA Chairman Richard Micka, and Refuge Manager John Hartig.

Michigan Sea Grant representatives Steve Stewart and Mary Bohling with John D. Dingell, Jr., IWRA Chairman Richard Micka, and Refuge Manager John Hartig. Photo by Mark Messer

FOR IMMEDIATE RELEASE

Contact:

  • Rhett Register, Michigan Sea Grant Communications Lead, (734) 647-0767, rregist@umich.edu
  • Cindy Hudson, Michigan Sea Grant Extension Communications Manager, (517) 353-9723, hudsoncy@msu.edu

The International Wildlife Refuge Alliance (IWRA) and the Detroit River International Wildlife Refuge recently honored the work of Michigan Sea Grant with the John D. Dingell Friend of the Refuge Award.

Michigan Sea Grant staff have been involved with both the IWRA and the Detroit River Refuge since they were organized. The IWRA recognized Michigan Sea Grant’s continued efforts in providing classroom and vessel-based education in southeast Michigan and their ongoing commitment to the mission of both the IWRA and the Refuge.

The Detroit River International Wildlife Refuge consists of nearly 6,000 acres of unique habitat, including islands, coastal wetlands, marshes, shoals, and waterfront lands within an authorized boundary extending along 48 miles of shoreline. 

The IWRA is a nonprofit organization dedicated to supporting the mission and purposes of the Detroit Refuge, the only international refuge in North America. It provides many vital services to the Refuge, such as community outreach, education programs, habitat restoration, special events support, volunteer staff, advocacy, and fundraising.

“The Refuge is such a wonderful asset to the Detroit area,” said Mary Bohling, a Michigan Sea Grant Extension educator. Bohling also is a current board member and one of the original organizers of the International Wildlife Refuge Alliance. “The Alliance has been an important part of building fantastic partnerships to help protect, conserve, and manage the Refuge’s wildlife and habitats. As a Sea Grant educator, I’m very proud to have been a part of making this happen.”

Since 1991, more than 100,000 students and adults have participated in Michigan Sea Grant’s Great Lakes Education Program. In addition to classroom lessons, students, teachers, and adult chaperones board the schoolship Clinton to learn more about conservation and stewardship of our state’s Great Lakes and waterways. Soon students will be boarding the schoolship at the newly constructed fishing pier and boat dock in the Detroit Refuge Gateway. The accessible dock and fishing pier are expected to open in the fall of 2017.

“We’re honored to receive this John D. Dingell Jr. Award,” said Extension Educator Steve Stewart on behalf of Michigan Sea Grant. “We’re also looking forward to welcoming many more students on board the Clinton from the new dock at the Refuge Gateway. It is critical that students have the opportunity to experience and learn about these incredible water resources, and there is no better way to do that than on a schoolship. They will be our future decision-makers and the stewards of these incredible water resources.”

The award is named after former Michigan U.S. Congressman John D. Dingell Jr., who championed many conservation causes and legislation, and who supported the creation of the Detroit Refuge.

Michigan Sea Grant helps to foster economic growth and protect Michigan’s coastal, Great Lakes resources through education, research, and outreach. A collaborative effort of the University of Michigan and Michigan State University and its MSU Extension, Michigan Sea Grant is part of the NOAA-National Sea Grant network of 33 university-based programs.

What’s the best fish to stock in your Michigan fishing pond?

Stocking the wrong species can lead to problems down the road.

Rainbow trout, such as these, are used to stock cold-water ponds. Photo: Ron Kinnunen

Rainbow trout, such as these, are used to stock cold-water ponds. Photo: Ron Kinnunen

Spring is the time of year to evaluate the type and quantity of fish to put in your farm pond. This is a critical decision as it will dictate the quality of fishing in the pond for years to come. Many make common mistakes when stocking fish into their pond that includes stocking the wrong type of fish species or the wrong combinations of fish species that are not compatible with each other.

Warm-water ponds

If you have a warm-water pond it is best to stock largemouth bass. A common mistake when stocking largemouth bass is to also stock bluegills with them. Many think that stocking the bluegills will provide forage fish for the largemouth bass and enhance their growth. Bluegills have the tendency to overpopulate the pond, monopolize the food supply, and stunt out in growth. Largemouth bass in our northern climate have a difficult time keeping bluegill populations in check. When stocking largemouth bass, it is best to have an established minnow population that they can forage on. These minnows can include fathead and bluntnose minnows.

Bluegills are many times stocked in Michigan ponds as the sole fish species. Several years of good fishing will occur after initial stocking of bluegills but over time they will overpopulate the pond, severely deplete the food supply, resulting in decreased growth rates that are not conducive to good quality fishing. Even as the growth of the bluegills decreases they will still remain very prolific producing even more bluegills which will tax the food supply. As an alternative to stocking bluegills, some will stock hybrid sunfish which is a cross between a green sunfish female and bluegill male. This hybrid cross results in the production of mostly male fish which can reduce reproduction in the early years resulting in larger growth and better quality fishing. But over time reproduction will occur and the quality of the fishery will be reduced.

Cold-water ponds

If you have a cold-water pond, you can stock trout. The best species to stock are brook and rainbow trout. These two fish species can also be stocked together. Avoid stocking brown trout as they are difficult to catch and as they grow they will eat other trout making it difficult to restock your pond. When stocking trout do not stock any other species of fish with them including minnows. Minnows will compete with trout for feed and reduce their growth rates. For trout, there is no need to stock forage fish. There are plenty of natural foods, such as aquatic insects, that inhabit the pond on which the trout can feed.

Avoid cool-water fish

Avoid stocking cool-water fish, such as yellow perch, walleye, and northern pike in ponds. These fish need large open water systems and will not do well in ponds. Yellow perch like bluegills are prolific breeders and can soon overpopulate a pond, monopolize the food source, and stunt out.

And never use grass carp to solve excessive aquatic plant growth problems as it is illegal to possess this fish species in Michigan.

How much do lake trout and Chinook salmon really eat?

Chinook salmon have been the most important predator in Lake Michigan for decades. With baitfish on the decline, some anglers believe that lake trout are now eating more than salmon.

It takes a lot of food for a lake trout to grow this big, but a Chinook salmon eats much more on an annual basis.

It takes a lot of food for a lake trout to grow this big, but a Chinook salmon eats much more on an annual basis. Photo: Michigan Sea Grant

The food supply in Lake Michigan is not what it used to be. Invasive species like quagga mussels, nutrient reductions in open waters, and high numbers of predatory fish to feed all play a role in “squeezing” baitfish like alewife. The result can be an imbalance of predators and prey. In other words: too many mouths to feed for the amount of food available in open water.

Of course, this is a simplistic way of looking at things. Different species of fish are not the same in terms of the energy they consume and use. They grow at different rates, prefer different water temperatures, and utilize food more or less efficiently.

These factors become important when considering the total number (or biomass) of baitfish being consumed by predatory salmon and trout in Lake Michigan. Many anglers are particularly concerned about the impact of native lake trout versus introduced Chinook salmon. Both species are currently stocked in Lake Michigan, but both species also reproduce naturally.

Chinook salmon are prized gamefish with a very high growth rate and a short lifespan — they typically spawn and die at age 2.5 or 3.5 with a very few surviving to age 4. Lake trout are also a good gamefish, but they do not draw anglers to the lake in the same way that the spectacular fighting ability of the Chinook salmon does. Mid-sized trout are excellent table fare, but large, old lake trout tend to accumulate more contaminants than salmon. Lake trout can also live much longer than salmon (over 20 years), but they grow much more slowly.

Since there is a limited number of baitfish in the lake, there is a limited amount of energy (calories) available to trout and salmon. How does this all play out in terms of the amount and types of prey fish being eaten by lake trout and Chinook salmon?  To find out, I relayed some questions on the topic to two people who have been studying Lake Michigan fish for a combined total of over sixty years: Chuck Madenjian (USGS) and Jory Jonas (MDNR).

How would a lake trout and Chinook salmon compare in terms of the energy they consume each year?

C.M.: For the period of time from age 1 through age 12, annual food consumption by a lake trout in Lake Michigan averages 13 lbs. This estimate is based on the assumption that the annual food consumption for age-10 and age-11 lake trout is similar to that for lake trout of ages 7-9. For the period of time from age 0 through age 3.5, annual food consumption by a Chinook salmon in Lake Michigan averages 42.5 lbs. Thus, Chinook salmon in Lake Michigan are feeding at a rate more than three times higher than that of lake trout.

J.J.: I agree with Chuck’s summary above, but would also add that Chinook salmon grow faster, inhabit warmer waters than lake trout on average, and are much more active. All of these factors lead to increased demand for energy (food) relative to lake trout.

So, on an annual basis a Chinook salmon eats more than a lake trout of the same size. We know that lake trout live longer than Chinook salmon, though. How much does an average lake trout eat over its entire lifetime as opposed to an average Chinook salmon?

C.M.: The answer to this question partly depends on the definition of an entire lifetime for a lake trout. Based on the bioenergetics modeling by Don Stewart and others, an average lake trout consumes 143.3 lbs. of food between the time of stocking as a yearling into Lake Michigan and age 12. A Chinook salmon consumes 147.7 lbs. of food between the time of stocking as an age-0 fingerling into Lake Michigan and age 3.5, when a Chinook salmon is ready to spawn.   

J.J.: Chuck did a nice job of summarizing lifetime consumption of the two species above. When asking a question like this, it is important to consider why it is being asked. Total lifetime consumption of prey does not equate to information valuable in determining sustainability of the system. New year-classes of fish are always being produced and individual species have different life-spans and life-histories. Several generations of alewife and Chinook salmon will have cycled during the life-span of a lake trout. For example, during the lifespan of a lake trout age 12 which consumed 143.3 lbs. of prey there will have been four generations of Chinook salmon each consuming 147.7 lbs. of prey (590.8 total lbs.). Because of fluctuations in births and deaths and the lack of life-span synchrony among species, we typically summarize population levels of predators and prey on an annual basis in order to monitor for changes over time.

Fish are cold-blooded animals, so water temperature must affect how often they eat and how quickly they digest food. Do temperature preferences play a big role when comparing bioenergetics of lake trout and Chinook salmon?

C.M.: Temperature does play a role when comparing bioenergetics of lake trout and Chinook salmon. However, the main driver of the difference in consumption rates between lake trout and Chinook salmon is the difference in growth rates between the two species. In other words, the main reason for the much higher rate of food consumption by Chinook salmon compared with that by lake trout is that Chinook salmon grow substantially faster than lake trout. Average summer temperatures experienced by lake trout in Lake Michigan range from 46.4 to 50°F, whereas average summer temperature experienced by Chinook salmon in Lake Michigan ranges between 53.6 and 55.4°F. Metabolic costs typically increase with increasing temperature, and so Chinook salmon would be expected to have higher metabolic rates than lake trout. Nonetheless, the primary reason for the higher food consumption rate for Chinook salmon compared with that for lake trout is the higher growth rate by Chinook salmon compared with that for lake trout.

J.J.: Chinook salmon are also more active than lake trout, travelling large distances and generally moving around more. Combine higher activity levels with the factors mentioned by Chuck above, including higher temperature occupancy, and you have a higher demand for calories to support Chinook salmon.

Fish need energy to maintain basic body functions, chase down prey, and reproduce. Additional energy can be used for growth. How do lake trout and Chinook salmon compare in terms of their ability to use food energy for growth?

C.M.: Gross growth efficiency (GGE) is equal to growth (increase in weight) divided by the amount of food consumed to attain that growth. Thus, GGE is a measure of the efficiency with which a fish converts food consumption into its growth. According to the bioenergetics modeling by Don Stewart and others, the GGE for a 3.5-year-old Chinook salmon is 13.3%. That is, the 3.5-year-old Chinook salmon converted its food into its growth with a 13.3% efficiency. The GGE for a 12-year-old lake trout is estimated to be 8.0%. Thus, a Chinook salmon is considerably more efficient at converting food into growth than a lake trout in Lake Michigan.

Large, old lake trout are a common catch in central and southern Lake Michigan. These fish might weigh over 20 pounds and be 20 years old or older. Computer models that calculate how many baitfish are being eaten in Lake Michigan treat a 20-year-old lake trout the same as a six-year-old. Does a 20-year-old lake trout really eat only as much as a six-year-old?

C.M.: To answer this question, a growth trajectory for lake trout from ages 1 through 20 would be needed. Stewart et al. (1983) estimated mean weight at age for ages 1 through 10 only, so information on mean weight at age for ages 11 through 20 would be needed to answer this question. According to Stewart et al. (1983), annual consumption of food by an average lake trout in Lake Michigan remained relatively constant at a value of about 17.6 lbs. between the ages of 6 and 10. In other words, annual feeding rate of lake trout did not increase as lake trout age increased from 6 to 10. Mean weight at age 6 was 6.6 lbs., and mean weight at age 10 was 10.6 lbs. Thus, even though the weight of an average lake trout increased by 4 lbs. between ages 6 and 10, annual rate of food consumption by lake trout did not increase between ages 6 and 10 (Stewart et al. 1983). Note that annual weight gain by lake trout decreased between ages 6 and 10. If the annual weight gain (annual growth) continued to decrease between ages 10 and 20, a large increase in annual consumption over ages 10-20 would not be expected.

J.J.: It is true that larger fish on average require more energy than smaller fish, all else being equal. As lake trout age, the annual growth rate is much less, reducing energy demands, as mentioned by Chuck above. In more recent catch-at-age modelling efforts in eastern Lake Michigan, the mean weight of a lake trout at age 6 was 5.7 lbs., at age 10 was 9.7 lbs. (a change of 4 lbs. in 4 years) and was 11.2 lbs. at age 15 (an increase of 1.5 lbs in 5 years). By age 7 most lake trout are spawning so fish age 7-15 should be experiencing similar energy demands for spawning. Despite this, growth rate (body weight added per year) continues to decline as the fish ages.

Studies on Great Lakes salmon and trout bioenergetics were conducted back in the 1980s. Do they still hold true today with so many invasive species in the food web and changes to the strains of lake trout being stocked?

C.M.: Bioenergetics models for Chinook salmon and lake trout are sufficiently flexible such that they can accommodate changes in the Lake Michigan food web and changes in lake trout strains being stocked. Inputs to the bioenergetics models include growth of the fish (predator), temperature regime experienced by the fish, diet schedule for the fish, energy density of the prey, and energy density of the fish (predator). All of these inputs can be adjusted to more accurately reflect changes in the food web or changes in lake trout strains stocked. Bioenergetics model estimates of food consumption by Chinook salmon and lake trout are especially sensitive to estimates of growth by Chinook salmon and lake trout, so changes in growth over time would need to be taken into account when estimating food consumption by these fishes over decades of time. In the laboratory, the lake trout bioenergetics model performed equally well for both Marquette and Seneca Lake strains of lake trout, so lake trout bioenergetics was very similar among strains of lake trout. The Seneca Lake strain does inhabit slightly cooler water than the Great Lakes strains of lake trout, but this slight difference in temperatures between strains had only a small effect on food consumption. Laboratory performances of both the Chinook salmon bioenergetics and the lake trout bioenergetics model are reasonably good. On average, the model estimates of food consumption are within 5% of observed consumption.           

Now we know how much individual trout and salmon eat, but how many baitfish are eaten annually by all predators in Lake Michigan? How did estimated lake trout consumption compare to estimated Chinook salmon consumption on a lakewide basis in 2016?

J.J.: In 2016, lake trout consumed 13.7 kt of prey and Chinook salmon consumed 38.4 kt. Even though numbers of Chinook salmon in 2016 were at all time low levels lake-wide, they consumed nearly 3 times as much forage as lake trout. In 2016, the biomass of Chinook salmon in Lake Michigan was estimated to be 5.0 kt and lake trout 5.9 kt. Just four years’ prior, in 2013, Chinook salmon biomass was substantially higher at 15.7 kt and lake trout were 7.0 kt.

Until now we have only been discussing how many baitfish are being eaten, but we know that Chinook salmon depend almost entirely on alewife while lake trout can eat a variety of prey including round gobies. Have lake trout moved away from eating alewife in Lake Michigan?

J.J.: Lake trout tend to be opportunistic feeders and will take advantage of a variety of prey items, whereas Chinook salmon are more specialized preferring almost exclusively alewife as prey. Since about 2003, lake trout have been taking advantage of a relatively new prey source in Lake Michigan, the round goby. Because of increased public interest in understanding the role of lake trout as predators in Lake Michigan, a variety of new initiatives have begun to better understand this more complex predator. For the last few years, diet collections have been occurring outside of the standard spring assessments which conclude in mid-June, and on broader spatial scales. Preliminary comparisons indicate that there is a seasonal component to lake trout feeding whereby they consume larger numbers of round goby in the spring and increased dependence on alewife as the year progresses. Smelt and bloater have been abundant in the diets of lake trout in the past, but for the recent 5 years over 75% of lake trout diets have been comprised of alewife and round goby. We continue to explore new and more robust methods for keeping up with the changing trends in lake trout consumption. Some of these include evaluation of fatty acid or isotopic signatures which can represent a longer period of lake trout consumption (in the case of isotopes up to one-year). We are seeking funding to conduct broader data collection efforts to better understand changing patterns throughout the lake and in different seasons.

So, we don’t yet know exactly what percentage of Lake Michigan lake trout diet is alewife, but what was the realistic range of possible alewife consumption by lake trout in 2016?

J.J.: It’s still early, but most of us are comfortable with an average alewife diet proportion of around 50% for lake trout, which we currently use in consumption models. Preliminary investigations indicate that in the spring (April to mid-June) alewife comprise between 7% to 20% of the diet of lake trout, and from mid-June to August alewife can represent from 50% to 80% of the diet. We continue to pursue improvements to describe feeding patterns of this more complex predator in the Lake Michigan basin.

Thanks Jory and Chuck for providing detailed answers to these questions.

In summary, when anglers point out that lake trout need more food to reach a given weight they are correct. A lake trout needs about 125 pounds of food to reach a weight of ten pounds while a Chinook salmon needs around 75 pounds of food (based on differences in gross growth efficiency). However, the Chinook salmon consumes this amount of food over a very short period of time when compared to a lake trout.

In fact, a typical Chinook salmon consumes roughly three times as much food in a given year as a typical lake trout does. This is critically important because alewife (and other prey fish) reproduce and grow each year. The absolute amount of food consumed by a salmon or trout in its lifetime is therefore less important to maintaining a good predator-prey balance than its annual demand for prey.

Chinook salmon do burn through alewife much more quickly than lake trout, but that does not mean that lake trout consumption is completely insignificant. Science is always improving, and the upcoming study on predator diets is one example of an effort to better understand what lake trout are eating at different times and in different parts of Lake Michigan.

Despite the never-ending quest for better information, fishery managers must make decisions in real time based on the best available scientific information. We know that an individual Chinook salmon consumes more alewife than a lake trout does, but we also know that Chinook salmon are no longer the only important species to consider when looking at predator-prey balance in Lake Michigan. In the future, scientists will be taking a harder look at diet and consumption of other predators like lake trout, coho salmon, and steelhead.

More information:

Michigan Sea Grant helps to foster economic growth and protect Michigan’s coastal, Great Lakes resources through education, research and outreach. A collaborative effort of the University of Michigan and Michigan State University and its MSU Extension, Michigan Sea Grant is part of the NOAA-National Sea Grant network of 33 university-based programs.

References

Bergstedt, R.A., Argyle, R.L., Krueger, C.C., and Taylor, W.W. 2012. Bathythermal habitat use by strains of Great Lakes- and Finger Lakes-origin lake trout in Lake Huron after a change in prey fish abundance and composition. Transactions of the American Fisheries Society 141(2): 263-274.

Madenjian, C. P., D. V. O’Connor, S. M. Chernyak, R. R. Rediske, and J. P. O’Keefe. 2004. Evaluation of a chinook salmon (Oncorhynchus  tshawytscha) bioenergetics model. Canadian Journal of Fisheries and Aquatic Sciences  61:627-635.

Madenjian, C. P., S. R. David, and S. A. Pothoven. 2012. Effects of activity and energy budget balancing algorithm on laboratory performance of a fish bioenergetics model. Transactions of the American Fisheries Society 141:1328-1337.

Madenjian, C. P., S. A. Pothoven, and Y.-C. Kao. 2013. Reevaluation of lake trout and lake whitefish bioenergetics models. Journal of Great Lakes Research 39:358-364.

Stewart, D.J., and Ibarra, M. 1991. Predation and production by salmonine fishes in Lake Michigan, 1978-88. Canadian Journal of Fisheries and Aquatic Sciences 48: 909-922.

Stewart, D.J., Kitchell, J.F., and Crowder, L.B. 1981. Forage fishes and their salmonid predators in Lake Michigan. Transactions of the American Fisheries Society 110: 751-763.

Stewart, D.J., Weininger, D., Rottiers, D.V., and Edsall, T.A. 1983. An energetics model for lake trout, Salvelinus namaycush:  application to the Lake Michigan population. Canadian Journal of Fisheries and Aquatic Sciences  40: 681-698.

Student video promotes awareness of Great Lakes marine debris

While plastic monsters invade Michigan’s Great Lakes and inland waterways, Alpena Elementary students create video to foster awareness of this issue among their local community.

Alpena Public Schools students get ready for action while filming their video

Alpena Public Schools students get ready for action while filming their video “Plastics 101.” Photo: RC Laugal

What is marine debris? It’s essentially human-made trash – large and small – that finds its way to oceans, our Great Lakes and inland waterways. A group of fifth-grade students from Alpena, Mich., want to help everyone understand what it is and what can be done to fight this problem. They created a movie and offer ideas about how everyone can contribute toward solutions. Watch their student-created film at: http://bit.ly/Plastics101.

The National Oceanic and Atmospheric Administration (NOAA) has championed an initiative to foster awareness, understanding, and citizen engagement in a growing issue of marine debris in our oceans and inland waterways. Through the Northeast Michigan Great Lakes Stewardship Initiative (NEMIGLSI) network, Michigan Sea Grant, Michigan State University Extension, and the NOAA Thunder Bay National Marine Sanctuary are partnering with schools, educators, and youth leaders to raise local awareness about this Great Lakes problem.

How did these students get involved?

In fall 2016, Bob Thomson’s Ella M. White Elementary fifth-grade students visited Thunder Bay River, where they used nets to trawl for plastics, and were shocked to find microplastics in our Northeast Michigan watershed. After analyzing samples from the river, fifth-grader Tucker Bright said, “If there are this many microplastics in this little sample, just imagine how many there are in the Great Lakes!” To raise awareness about finding plastics in the river and finding solutions to this problem, these Alpena Public Schools students developed a film, “Plastics 101.”

Through the NEMIGLSI network, they worked with community partners, including Huron Pines AmeriCorps, Michigan Sea Grant, and Thunder Bay National Marine Sanctuary, to complete the film. The effort also was supported by DonorsChoose.org through Tom’s of Maine Green Your School Campaign.

Before filmmaking, the students researched the topic of marine debris and found that microplastics are a problem in both our Great Lakes and oceans. The students consulted with fisheries expert, Brandon Schroeder (Michigan State University Extension, Michigan Sea Grant Educator), and microplastics expert, Dr. Sherri Mason (Professor of Chemistry, The State University of New York at Fredonia), to verify their research. Next, the students outlined the films’ goals and began creating a storyboard. The students also crafted props, recorded audio, captured video footage while having fun and learning.

‘Plastics 101’

The film “Plastics 101” emerged with entertaining insights into the troubles of a throwaway culture and the effects on the Great Lakes and oceans. Students also learned about potential career options while applying classroom learning goals. Thomson said, “The video provided a perfect opportunity to develop a cross-curriculum project that focused on targets from English Language Arts, Science, and Social Studies.” Thomson recently was named 2017 Michigan Science Teacher Association Elementary Science Teacher of the Year.

Students also learned more about how their actions impact their community and ultimately the world. When plastics are improperly disposed, they could end up in a local stream, river, or the Great Lakes by the wind, rain, and through storm drains. Students were surprised to learn plastics absorb toxins, such as DDT, PAH and PCBs, and that these toxins can enter our food web through plastics. Since plastics don’t biodegrade, they don’t go away; they simply photodegrade into tiny pieces that can be consumed by plankton or small fish and then move up the food chain. To showcase solutions to this problem, the students highlight how to take action and protect our Great Lakes and ocean.

“Plastics 101” now will serve as an educational tool through the Northeast Michigan Earth Day Bag Project, an effort where third-, fourth-, and fifth-graders learn about the harms of single-use plastics to our Great Lakes and ocean and solutions to this growing problem. After watching a series of short films and discussing the information, students across northeast Michigan will decorate paper bags with conservation messages (e.g. Refuse to Single Use; Protect our Great Lakes), which will then be distributed to customers at local grocery stores on Earth Day, April 22, 2017.

Michigan Sea Grant and Michigan State University Extension serve in providing leadership for the NEMIGLSI network, which is part of a larger, statewide network and partnership, the Great Lakes Stewardship Initiative (GLSI). Established in 2007 with funding from the Great Lakes Fishery Trust, the GLSI supports place-based stewardship education in schools and communities across Michigan. Partnerships are invaluable in our endeavor to support stewardship of our Great Lakes and natural resources.  Through the NEMIGLSI network, and applied place-based education strategies, our students may perhaps prove the most inspirational educators of all in addressing important Great Lakes issue such as marine debris.