Sir Sandford Fleming School of Natural Resource Sciences in Lindsay, Ontario, Canada is home to the Lake Simcoe Muskellunge Restoration Project’s muskellunge hatchery. Here, nestled in rural Ontario, hatchery technician Mark Newell has pioneered the techniques to successfully raise this challenging species in a hatchery setting.
“One of the first things I tell students is that you need to think like the species you are raising,” says Newell. “In our case you need to think like a Muskie, which is a fish-eating top predator.”
Muskie (Esox masquinongy) are voracious piscivores and prone to cannibalism like many other cultured predator species. Hatchery technicians were often left with a few very large Muskie fingerlings in their tanks, voracious survivors which have devoured most of their tank-mates.
It’s well recognized that proper feeding should minimize cannibals in any stock of fish. Indeed, a fish presented with enough manufactured feed should satiate itself with feed and mitigate cannibalism. Easy to say, but not so easy to carry out.
Getting a wild-strain piscivore to accept commercial feed isn’t an easy path and has been the major stumbling block with previous Muskie culture trials. The major success at SSFC Muskie Hatchery has come from what Mark Newell calls pellet training: getting muskie to eat a commercial diet until just before release when they are switched to a live fish diet to prepare them for the wild.
Successful Muskie pellet training comes down to two simple concepts: timing and presentation. To have a presentation that Muskie find attractive you must think like a Muskie. After Muskie fry have absorbed their egg sacs and begun to feed in the wild they are planktivores.
“This is the critical period when you can get Muskie onto feed,” says Newell. There is only a one-week window to ensure that the first meal is a pellet. If this window is missed chances for success greatly decrease. 0.3mm crumble is given at this stage which is roughly the same size as the zooplankton Muskie eat. From this point pellet size is incrementally increased as the Muskie grow until the fall when they are switched to live minnows.
For a Muskie to eat pellets they must be presented just-so. Try to feed Muskie like trout and the results will be poor. A muskie is an ambush predator and needs to stay motionless, to focus on an individual target, coil and strike. Too much feed in the water only confuses a muskie and the fish can starve despite large amounts of food available. Presentation is indeed everything. Agitation is required; muskie won’t strike a target that isn’t moving. Careful observation of the feeders and the tank aerators must be maintained to keep pellets moving just enough to trigger strikes but not force the Muskie to swim against the current.
Variability amongst the stock means that all Muskie won’t accept feed the same way. Some Muskie will not take feed from the surface and must have the feed sink. Other fish will not take a pellet no matter what the presentation and eat their fellows.
Newell has adapted an old style of feeder to help with customized Muskie feeding regimes. The clock face feeder has been around for years, being both inexpensive and reliable. It is basically a clock with the minute and second hands cut off and slits or holes cut at each number on the face that feed can fall through. Feed is placed on the face of the clock and the hour hand pushes feed into the slits and down to the fish. By raising and lowering the feeder and placing the aerators offset below, one can achieve a mix of floating and plunging feed. The muskie will line up around the feeders, each with its own little striking zone. Observing this line-up behavior is a good indication that the fish are accustom to pellets. The clock faces are easy to make and are highly customizable while the clock motors are inexpensive and reliable. The feeder also provide cover for the Muskie to shelter under.
Once pellet trained, Muskie line up under the clock feeders ready to dash forward and strike a pellet
Being such a voracious predator cannibalism is still an issue despite pellet training. Diligent observation is required, especially during those first few weeks of pellet feeding, to weed out the cannibals. It is a labour intensive process.
“Once a muskie has two fish meals it will not go back on pellets,” says Newell. Observed cannibals are removed from the general population right away and clock feeders are set and checked meticulously each day to ensure pellet presentation.
Habitat and water quality
Muskie inhabit the still waters and the shallows where they can sit unmoving and attack passing prey. The ideal muskie rearing unit reflects this. Round tanks, so very appropriate for many other species, are not ideal for the muskie – too much current. Surprisingly, it is rectangular tanks that serve well for muskie.
Relatively higher tolerances to ammonia and low oxygen than salmonids allow muskie to live in what amount to giant aquariums (minus the glass). Because of the specific way a muskie targets individual pieces of food they will not take feed once it hits the bottom of the tank. Siphoning waste and water changes, though labour intensive, allow for detailed observation of the tank and the fish. Muskie fry are first kept in floating half barrels within the larger fish tank for easier access and feeding. Floating barrel halves give a smaller space to rear while biomass is small, but a much great water volume for exchange. Fish transfers can also be accomplished without handling by simply sliding out the barrel, leaving the muskie and water behind in the larger tank.
What started as a small restoration project aimed at releasing a few hundred fish for Lake Simcoe has through painstaking development of rearing techniques increased its production to 2000 fall fingerlings each year. Pellet training and thinking like a muskie has pioneered muskie culture and allows Mark Newell to produce as many muskie fingerlings as hatchery size and egg availability allows.
— Ron Hill
Muskellunge Egg Shortage
This year’s Muskellunge egg collection ran into poor conditions causing reduced egg availability for Sir Sandford Fleming College’s Lake Simcoe Muskellunge Restoration Project. Instead of the usual output of 2000 fingerlings, Mark Newell, hatchery technician at SSFC, expects an output of only 500 fingerlings for Lake Simcoe this fall.
Wil Wegman, Resource Management Technician at the Ontario Ministry of Natural Resources and Forestry, blames the shortfall on poor spring weather conditions.
“The cause is likely cool water temperatures to start, followed by a drastic spike in temperatures during the sixth week of trap-netting (last week of May) when water temperatures rose to the 200C range. Water temperatures held at just 110C for 2-3 weeks, [before it spiked to 200C] so it was cooler than the 14-150C which is preferable [for muskellunge spawning].”
When asked if these collection problems reflect a shortfall in the muskellunge population in Lake Simcoe he indicated it did not and that, “It’s very important to keep in mind that weather and water temperatures are often the driving force to determine how successful a muskie egg collection is. Some years […] are extremely successful and other year’s numbers are lower.”
Blue Jay Creek Hatchery and Sir Sandford Fleming College staff are trying new strategies to maximize fry survival in light of the egg shortage. Live minnows are being introduced earlier to fry. Cannibals and fish which reject pellet feed are sorted out and put on a diet of small minnows to get the most out of the stock.