depending upon the lake,what section of the lake,water temps,etc. the mayfly hatch is happening,about 1 week sooner than most seasons.
many expect it to be or assume it to be the kiss of death for a trip. actually the start of the hatch typically stimulates a very active feeding period.
spend time looking for areas on your maps that have spread out contour lines vs tight close together indicating flats and slow tapering bottoms. bays,flats between islands,areas that typically have weed beds in the summer,even deeper mud bottomed areas,also rocky points,bars,shelves coming off shorelines adjacent or in the middle of these types of areas as some fish are also seeking out molting crawdads as well as minnows bunching up shallow when the sun comes out and shallows warm. these are the types of areas that will draw large numbers of fish seeking the hatching larvae and or other feeding opportunities.
jigs still catch lots of fish and some never quit using them. you can cast to shallower or bunched up fish or slowly troll and snap jig to cover ground.try browns,golds,purples,dark blue,and chart or org on darker days,tip with smaller dace or fatheads,leeches,crawler tails or snap jig gulp or plastics.
covering ground looking for concentrations or picking up scattered roaming fish especially if you don't have the experience on the lake and knowing the spots on the spots that fish have a tendency to group up on on these larger flatter areas is tailor made for spinner rigging and trolling crank baits. also these presentations will trigger fish that are in less than an aggressive feeding mode.
spinner rigs can be tipped with minnows or gulp,leeches,or 1/2-3/4 of a nite crawler. use smaller #2-4 blades and if you are seeing hatching flys as you fish in the evenings or early ams a very small #0-1 gold spinner with 2-3 org beads and the tail of a crawler very slowly elec trolled and pulled up towards the surface then allowed to flutter back can be deadly.
leeches and crawlers can be the bait of choice on many lakes during the hatch and a dessert like a wiggling leech on a slip bobber or small floating jig head will put extra fish in the boat.
cranks trolled a little quicker will trigger bites like flicker shads,shad raps,tail dancers,etc the #5 #7's sizes run at just the right depths with 50-70' of line out, same with minnow baits like reg raps,rattl'n rouges,yorouris ,etc in #9 an #11 sizes with a #5 split shot 18-24" ahead will also do the trick at these depths.i've also seen guys do very well especially on larger fish casting or trolling smaller rattle traps.
good luck and don't use the hatch as an excuse why fish are not apprently biting,stay positive and you'll still catch plenty of fish.try some diff approaches,mix up patterns,try fishing pike,muskys, or trout in the am after a heavy hatch nite and hitting the walleyes in the pms. if the water cools and the hatch stops go after them right away. move to a deeper colder section of the lake or a shallower darker section if the deeper section is hatching,or make a total lake change are also considerations if you are into the later parts of a hatch that has been going on for more than a week or so.
good luck!!