Why am I Seeing so many Dead Bass on the Main Lakes?
The Main Chain of Canadian Lakes is experiencing an abnormally high mortality rate of adult largemouth bass during the last month or so. There is a possibility that this high mortality is related to one or more viruses these fish are susceptible to. Specimens will be sent to fish disease expert Dr. Faisal at MSU for professional verification of the presence or absence of one of the most common and life threatening of these viruses, Largemouth Bass Virus (LMBV). This virus has been detected in many southern MI lakes and some central county lakes. The virus is only fatal to bass when they are exposed to extreme environmental or angler related stress. If it is determined the virus is present in CL, it most likely will not have a major detrimental impact on the Main Lakes bass population as a whole. If the virus is detected, the annual Bass Tournament should be moved to earlier or later in the season to coincide with cooler water temps and anglers should minimize handling of fish during the warmer months.
At this point we can conclude that with or without the presence of a disease (LMBV), the Main Lakes are experiencing high adult bass (and the occasional pike, perch, crappie...) mortality. The high mortality is most likely related to the extremely (record setting) warm July. With daytime water temps approaching 90 degrees F and overnight dissolved oxygen levels falling into stress inducing low levels, these fish can succumb to the environmental stress, especially if they are infected with LMBV. Remember, the older fish have not had to struggle through a summer like this in years. Angling pressure is at its highest during the summer months as well. On the Saturday of the CL Bass Tournament, 100's of fish were handled on just that day alone. We would recommend that fisher people suspend any major catch and release fishing outings until the water temps come back down in Sept. This is most likely not an epidemic, viral testing will be conducted, the bass fishery will survive and remain intact, but unfortunately we will likely see continued high mortality of adult bass well into August. Please respond with any questions or comments through the link provided on this page. We want to express our appreciation to everyone who collected specimens; thank you and we can resume burying dead fish as we have an ample amount of sample specimens.
Your Lake Managers, Joel Steenstra and Tom Krueger
posted by Summit Lab @ 12:49 PM
2 comments
2 Comments:
Taken from the michigan DNR web site. WE appreciate your efforts in lake management,However leaving it to manage it's self with out as much human intervention would be a better solution. Summit lab's is making large profits from CL for it's so called help.we spend money for stocking minnows and then eliminate thier habitate and thier places to hide by destroying the weed's what I think it comes down to is a bunch of lazy people don't want to rake thier beach or clean off thier silly pontoon boat props. Yes heat,stress and fishing perssure all are contributors to this problem BUT SO ARE CHEMICALS Deal with the weeds they are the sole oxygenator of the water.
The DNR cannot eradicate this virus or treat affected wild fish populations,” Whelan said. “However, as we continue investigating this disease, we appreciate receiving reports of unusual fish mortalities.” In 2002, many largemouth bass mortalities were reported during the mid-July to mid-August period and some of these were likely LMBV related. However, many of the reports came in weeks after the mortalities, which is too long for confirmation of the disease. In 2003, no large scale mortalities were reported which is likely from the mild summer weather conditions that reduced the stress on largemouth bass populations.
The disease usually causes mortality when fish are most stressed. Potential stressors include very hot weather, high angling pressure, and possibly aquatic weed or other treatments during very hot periods. Any measures that can be taken to minimize stress on these fish will reduce the impact of the disease and mortality.
Dear anonymous,
Thank you for taking the time to share your feelings with us. I realize fishery and weed issues can provoke emotional responses from lake users when we see unwanted change in our lakes. I too get passionate when I see lakes abused or mismanaged. Let me first assure you, for us it is not about the money, it never has been. When it comes to managing our aquatic resources we have never been motivated by money. However, this is a business and we do have expenses and overhead which need to be covered in order to stay in business. The profit margin from our account with C.L is small, actually very small.
As far as the lake plants go, they are not the "sole oxygenator of the water". Actually, too many plants will rob the water of it's dissolved oxygen. During the sunny daytime plants produce oxygen as a by-product of photosynthesis. During dark hours they are going through the process of respiration which consumes oxygen in the water and produces carbon dioxide (a poison to fish). So the net increase of oxygen in the water over the course of a day from plants is negligible. The real sole oxygenator of the water is the atmosphere. Oxygen diffuses into the water at the air/water interface. Wave action greatly increases the surface area of the air/water interface and allows for much greater oxygenation. There are several other reasons for the aquatic plant management strategy we are implementing in C.L., but it has already been explained in several different reports we have submitted. We are not trying to kill off all the weeds or let them amplify uncontrollably. We a striving for balance and biodiversity. A balance that will benefit the fishery and help stabilize the water chemistry which will lead to less need for chemical treatment. Thanks again. Tom Krueger
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