Walleye stocking of Lake Mindemoya deferred pending 2017 survey

Deferred decision could hold up proposed fish and game club hatchery at government docks in Mindemoya

by Expositor staff with files from Tom Sasvari

LAKE MINDEMOYA—The United Fish and Game Clubs of Manitoulin ( UFGCM ) is still awaiting a decision from the Ministry of Natural Resources and Forestry (MNRF) regarding an application the club submitted for a proposed walleye hatchery on Lake Mindemoya, and will likely be waiting a few years as the MNRF told the club at a recent meeting that it will be deferring any decisions regarding stocking the lake until reviewing the results of the 2017 Fall Walleye Index Netting (FWIN) survey.

“An application has been received and we are still in discussions with the club,” commented MNRF biologist with the Sudbury district office Wayne Selinger regarding the UFGCM’s proposed Lake Mindemoya walleye hatchery. “Given that decisions regarding stocking Lake Mindemoya have been deferred pending the results of the 2017 netting survey, we are uncertain as to whether the club should invest significant time and money in a new facility if the only intent for the facility is to stock Lake Mindemoya. We are encouraging investment in the existing Kagawong facility to increase capacity there. Having said this, approval of an additional walleye culture facility on the Island is not necessarily linked to a decision regarding Lake Mindemoya. There are other lakes on the Island to be stocked including Lakes Kagawong, Silver and Tobacco.”

After Mr. Selinger reviewed the results of the most recent walleye survey on Lake Mindemoya, the UFGCM expressed that they would like the next Lake Mindemoya FWIN to be carried out in 2016 because of the time it takes to complete and review the survey results.

UFGCM Chair Jim Sloss said that the MNRF report shows “that they had two year classes (walleye) that were failures and they want more data to see if this trend continues, (and if so) that they would have to consider stocking fall fingerlings because the lake is so big, and while we don’t disagree with that, we feel the need is there now.”

Despite the clubs’ wishes, Mr. Selinger said that the MNRF is “not committed at this point to do the survey in 2016.”

“We will consider what the club has requested and consider the revisited timing option,” added Mr. Selinger. “The problem I see is by doing the survey in 2016 it would mean getting information earlier, but there would be one year less data. We don’t want to rush in 2016 so we have four full years of data.”

“MNRF has evaluated the status of walleye populations in Lake Mindemoya five times since 1997 using the FWIN protocol,” said Mr. Selinger. “Walleye population dynamics have been irreversibly altered in Lake Mindemoya over this time period as a direct result of the introduction of invasive species (zebra mussels and rainbow smelt). Walleye abundance has declined significantly since 1997 due in part to reductions in primary productivity and zooplankton abundance owing to zebra mussels. Juvenile walleye feed primarily on zooplankton and reduced survival can be expected in response to food limitations caused by zebra mussels.”

“More recently, rainbow smelt were introduced to the ecosystem, at some point between 2005 and 2009 and the abundance of smelt has increased dramatically since 2009,” continued Mr. Selinger. “Smelt affect walleye population dynamics in two ways: smelt are a readily available, high energy food source and their presence has increased walleye growth, condition and survival; and, smelt have been blamed for recruitment failure in a variety of species including walleye as a result of competition for available zooplankton and predation on early life stages. Walleye recruitment in Lake Mindemoya is weaker and more sporadic presently than it has been in the past.”

“However, walleye are still recruiting naturally to the population in the presence of smelt as evidenced by a strong 2010 year class and a lesser 2011 year class,” explained Mr. Selinger. “Despite an 80 percent reduction in abundance, at the current level of productivity, the population still compares favourably against provincial benchmarks for expected biomass and sustainable mortality.”

“The new reality for Lake Mindemoya is simply fewer bigger walleye,” stated Mr. Selinger. “Carrying capacity has been reduced by zebra mussels and walleye are growing faster and maturing earlier in response to the presence of smelt. Unfortunately, such changes are irreversible.”

Mr. Selinger said, “some lakes invaded by smelt do end up requiring supplemental or put-grow-take stocking; however, the best course of action at the present time for Lake Mindemoya is to continue monitoring for natural recruitment. We plan to complete another FWIN survey in October 2017 in order to stay on a four-year cycle. Optimistically, we will see continued natural recruitment in the years ahead.”

Mr. Selinger summarized that, “It’s all about invasives, zebra mussels have had an impact on the production of the lake and the smelt can interfere with fish recruitment as well. If by 2017 there is no tangible recruitment, we will be all on board with stocking.”