…..As the water cools in late summer muskies begin to feed much more heavily in their preferred haunts.

In all but the northernmost musky habitats, the heat of summer can be physically tough on muskies.  In the northern extremes of the muskies’ home range, the heat of late June through mid August turns the fish on as waters stabilize in the low to mid 70’s.  This is still within the musky comfort zone and in fact promotes peak activity.  However, there is a fine line between temperatures that promote peak activity and temperatures that stress.  Muskies will tolerate water into the upper 70 degree range, but anything past that will cause them to leave for more tolerable conditions before they begin to stress.

The Science of Late Summer

In most bodies of water, muskies prefer to live and feed in shallow water (3-12’). As the heat of summer sets in, the shallows of lakes and rivers at about 46 degrees of latitude and southward begin to heat up past the point of comfort.  Waters in this range account for approximately 75% of the muskies’ total range.  Depending on the individual ecosystem and which alternate locations are available, muskies seek refuge in deeper water, faster moving water, near cool water inlets, or under heavy vegetative structure.  They don’t necessarily prefer these areas, but their bodily demands give them no other choice.

The heat of summer usually takes a while to break, but it usually happens in late August to early October depending on latitude.  As water surface temps. drop back down into the low 70’s F, muskies will move back to the territories they prefer.  No longer bound by the chains of hot water, the muskies are free to move and feed as they please.  Locating them at this time can allow a musky hunter to target some of the best musky feeding found any time of the year.

In 2008, from late August to early October I experienced excellent action in the metro area of MN as temperatures cooled.  Muskies became very active on their favorite weed edges and the cooling water caused algae blooms to die which improved water clarity.  Muskies were active and feeding mostly in narrow early morning windows, during favorable weather conditions, and under peak moon phases.

Main lake weed edges that had been ghost towns since early summer had numerous active large muskies working them.  I am not sure if these fish had left the areas all together during summer or if they had just taken refuge by digging into the deep dense vegetation.  The water shaded underneath dense vegetation is usually at least a few degrees cooler than the water above, and sufficiently oxygenated by the respiration of the aquatic vegetation.  Individual muskies probably choose one of the two options.

In the heat of the summer, muskies in a large river I fish leave shallow weedy areas they prefer because the areas warm past the point of comfort.  The fish that don’t go deep move to cool water inlets with little structure other than the breakline into the main river.  Good numbers of muskies inhabit these small areas and they are easy to present to, but the lack of structure causes muskies to be spooky and respond poorly to lures most of the time.  In late August, these fish immediately leave these areas as the water cools.  They move to adjacent weed edges and become much easier to catch.  Also, muskies move up from deep water haunts back to their favorite weed edges.

In smaller rivers with strong current flow, water in deeper holes can become stagnant.  Muskies usually prefer these deeper holes, because shallower areas rarely provide the cover and protection muskies depend on.  However, these deeper areas usually have much slower current and therefore the water in them can become stagnant if it is too warm.  When this occurs, muskies usually move into fast often shallow areas where the current moves water across their gills with little or no effort on the part of the musky.  This allows them to maintain proper amounts of dissolved oxygen in their bloodstream.  Structure emerging from the surface of the river help mix oxygen into the fast water.

In shallow fast areas, muskies will draw towards any available structure; a rock, log, or clump of weeds; but they will be very spooky, respond poorly to lures and anglers, and probably feed less as well.  When the water cools, they will go back to their favorite holes and go on the feed.  On the small rivers I fish in MN and WI the best month for this scenario is September.

Regardless of what type of environment I am fishing, I have to keep in mind that this is not a fall tactic, at least not what most musky fisherman would consider fall.  On bodies of water that turn over in fall, this bite concludes before the occurrence of turnover.  This is what I consider a late summer pattern that occurs at water surface temperatures of 74-62 F.

Effective tactics for late summer are diverse.  The same speedy presentations of summer will work and are great for covering water.  Topwaters are excellent, especially for working over shallow or dense structure.  Jerkbaits and soft plastics are excellent for areas known to have muskies that might be a little reluctant to strike.

Lakes

In lakes, muskies usually prefer to move up onto the edges of weedbeds on mainlake structure such as humps and reefs.

Islands can be good as well but I do the best on reefs.  For some reason, there is nothing like a reef that rises high off the bottom of the lake, and gets just shallow enough for weed growth all the way across the top.  In a clear lake, a reef that tops off in 10-15’ of water can have dense weed growth.  In a murky lake, the reef may have to come within 2-3’ of the surface to get enough sun to support weed growth.  A few large rocks on these weed edges can make a spot deadly.  Rocky reefs with no vegetation can be excellent, especially if muskies seem to prefer rocks in a particular body of water.

Some lakes do not have any mid lake structure.  Shoreline structure is the obvious choice on these lakes.  On lakes with scattered shoreline vegetative structure, running and gunning various scattered weed beds will eventually reveal which ones hold muskies.  Larger areas of vegetation usually hold muskies better than smaller patches of weeds.  On lakes with a continuous weed edge around the perimeter of the lake, some areas will consistently hold fish while others remain dead.  Sometimes there are characteristics to look for when searching out productive areas on a continual weed edge, but much of the time there is little rhyme or reason as to why the fish prefer one area to another.  On a continuous weed edge, look for points and pockets.  Also, the edge off a wide band of weeds that extends far from shore is usually better than a narrow band that does not extend far from shore.  This is probably because more forage is moving in and out of the wider area of vegetation.  More vegetation means more cover, it’s as simple as that.  Although, as I said before, what makes some areas more attractive to muskies is often a mystery to me.  Covering water and paying attention to details help to reveal these spots.

Fishing weed edges in lakes is not as simple as it sounds.  Weed beds are living changing structures, they are not at all similar to a favorite boulder pile that remains the same year after year.  Weeds beds, especially the edges, can change drastically from year to year, month to month, week to week, and even day to day.  Weeds are like crops in a farmer’s fields, some years are good for growing for various reasons and some years are not.  Depending on temperature, sunlight, wind, water levels, water clarity and precipitation; weed beds can flourish or grow very poorly from one season to the next.  From month to month and week to week during the course of a growing season, aquatic vegetation can experience growth spurts, slow periods of growth, periods of stability, slow die offs, and fast die offs.  Day to day changes can be caused by extreme weather events such as freak wind storms that can uproot and kill massive amounts of vegetation.

Musky location depends heavily on the changes in vegetative structure and tactical approaches must be tailored to fit exact structural configurations.  By late summer, weeds are long since done growing and on the decline.  They may have already been drastically depleted by summertime algae blooms that reduced sun exposure and caused death.  As late summer progresses, reductions in photo period (daily sun exposure) cause weeds to die off slowly and consistently.  The weed edge recedes, usually into shallower water because the depths aren’t getting enough sun to support growth later in the season.  Often this recession does not occur evenly, creating new points and depressions on the edge.  Muskies react to these changes by finding the areas most suitable for them amidst the changing conditions.  Last September, on one particularly good mid lake weed edge, I followed the weed edge back 15 yards from 14’ of water into 10’ over the course of the month and then the muskies simply vanished while other edges remained productive.  I found that some edges recede to the point that muskies no longer find them useful, while others continually hold muskies regardless of weed edge deterioration.  Again, why this happens I don’t know but trial and error will let you know when it happens.

Be diligent of the ever changing weed edge, new pockets and points are constantly emerging.  Be observant, targeting the changing edge and thoroughly picking it apart is challenging but it can be very rewarding.  Keeping lures close to the weeds is very important, but fouling in the weeds causes wasted casts.  Ripping a lure free from a weed top is an excellent trigger, but gobs if thick weeds will hopelessly foul a lure and waste the cast.  If the edge is dense and the weeds are high, high riding presentations and surface lures become necessary.  Semi weedless lures such as safety pin style spinners can also be good for working through heavy weeds.  Looking for slightly less active muskies just inside the edge can also be very productive.  Deeper running lures are excellent for working the base of the edge, but they will usually foul if cast inside the edge.

When working a weed edge along a reef or along a shoreline.  Stay a cast length away from the edge and work points and pockets at a near perpendicular angle from a distance to keep from spooking fish.  Don’t cast directly perpendicular from the boat to the edge, lead the boat by casting slightly ahead of the direction of the boat so the last part of the retrieve doesn’t drag behind the boat.  Then work the same structure over again working your boat right on top of the edge fishing parallel to the edge to hit anything you may have missed before, as well as showing the fish a different presentation angle.  Shallow running lures allow for the most error, as they foul the least in vegetation.  Also, they work best into the edge if muskies have tucked themselves in a bit.  However, sometimes deep running lures may be necessary if muskies are low at the base of the edge and refuse to rise in the water column, though these lures must be cast much more precisely to avoid fouling and wasted casts.

Large Rivers

On large rivers, the current is usually slow enough for weed growth to develop much as it does in lakes.  One factor that is a greater influence on weed growth in rivers than in lakes is water level fluctuation.  One case in point is a the lower St. Croix River on the WI/MN boundary waters.  In 2007, spring was very dry and the water level started low and stayed low all season.  The sand flats, sandy points, and sandy tributary deltas that harbor the river’s only weed growth were covered by water no deeper than 10’.  The low water in the river caused the current to run slower and thus caused little sediment movement, therefore the water was clearer.  The water in the river, like many other large rivers, runs from stained to murky.  Sunlight only penetrates so far into it.  In 2007 the sandy areas that grew weeds were shallower and clearer than usual and the weather was very sunny.  These combined factors caused tremendous weed growth.  In late summer when the water cooled, muskies moved into these areas heavily and took advantage of the lush growth.  I experienced excellent action in these areas from late August to early October.

2008 on the same river was very different.  April and May were much cooler and rainier.  The river was 4’ higher and murkier.  Only weed beds in the shallowest areas received enough sun exposure to develop.  When the water returned to normal in mid summer, these areas were covered by only a foot of water.  Weeds in deeper areas never developed.  Like any seasonal crop, they needed to start in spring or not at all.  The same areas had very little to offer muskies and therefore they barely used them.  They scattered throughout the vast system and locating any decent number of fish eluded me.

When conditions work out to have good weed growth in late summer on big rivers, the bite is very similar to fishing weed edges in lakes.  Water clarity in rivers is usually lower than clarity on lakes.  This means two different things.  First, edges must be worked from a slower moving boat, so that casts can be packed closer together.  This ensures that muskies using the edge will be made aware of your presentations.  Second, working them thoroughly is easier because the lower visibility allows the angler to get closer to the edge without spooking fish.  Topwaters, jerkbaits, and spinners are usually the most reliable presentations.

Small Rivers

In small rivers with fast current, as the water cools muskies move out of fast areas and into the slower holes that are traditionally thought of as river musky habitat.  Work structure closely, but scour out all areas of the hole to be thorough.  There are usually less holes than shallow runs so muskies will normally be a little more concentrated at this time.  If one musky is using a hole, it is a good spot and there are probably more fish using the hole.

Anchor outside of holes by slowly and softly dropping an anchor.  Use an oversized anchor so it doesn’t drag across the bottom.  A dragging anchor makes a lot of noise and can spook fish, as will an anchor that hits bottom too hard.  Stealth is the name of the game in small rivers.  Holes can be drifted through with the current, but this usually allows for only one or two casts.  An electric motor can be used against the current to work slowly through the hole, but keeping the bow from swinging around in the current is tricky, especially when adding the task of precision casting onto that.  Careful anchoring allows for the most control and thorough fishing.  Anchor above, below, or to the side of holes; whichever allows for the best casting angles into the hole and its structure.  Casting to a hole before going through it with your boat is best to avoid spooking fish, especially larger muskies which are very reclusive in small rivers.

To thoroughly work a hole, fish it through first with a topwater.  Then work it through just beneath the surface with a spinner or jerkbait.  After that, dredge out the depths with a crankbait or a soft plastic, though the crankbait will hang up less and put out better sound in the dark river water.

Bringing It All Together

As I mentioned earlier, most types of lures and tactics will work.  I recommend using lures and tactics you have confidence in, and getting out and fishing is the only way to develop this confidence.  Trolling will work to cover weed edges, but I prefer to cast and pick apart structure, it’s just my thing.  Lures that work the best for me under most conditions are smooth wide sweeping gliders.  Manta Hang 10’s account for most of my muskies.  All styles of large topwaters are also big in my arsenal.  I like big weighted diving jerkbaits for going deep.  Those I fish with do well on a multitude of spinners and large soft plastics.  In late summer, presentation choice boils down to confidence and properly covering target structure, I cannot stress this enough.

No matter what type of habitat I am fishing in late summer, I am looking for muskies reacting to the changing environment in a positive way.  The key is the change in water temperature and possibly a reduction of algae bloom and/or boating traffic.  If the change is not occurring, a hot bite is unlikely.  Look for muskies that are enjoying the cooler weather as much as you are, and the results should be good.