Trolling Techniques Explained: Speed, Depth, and Lure Selection
Trolling is the most systematic of all fishing methods: you set variables, run them until a pattern emerges, then adjust. Speed, depth, lure action, lure colour, spread width, and the distance each lure runs behind the boat are all independently tunable parameters — and the combination that produces fish one morning may be completely wrong by afternoon when the light changes or the thermocline shifts. This is what makes trolling simultaneously the most technical and, when it comes together, the most productive approach to covering large bodies of water and intercepting fish that are actively moving through the water column.
Flatline Trolling: The Foundation
Flatline trolling is the simplest version: a lure runs directly from the rod tip to the water, towed behind the boat at whatever depth the lure naturally tracks. A standard diving plug such as a Rapala Original Floater in size 11 will dive to roughly 1.5–2.0 m on 8 lb monofilament at 3 km/h. A larger diving lip on a plug such as the Rapala Shad Rap SR-9 will reach 3.5–4.5 m under the same conditions. The depth each lure achieves depends on three factors: the size and angle of its diving lip, the diameter and flexibility of the line (thicker line causes more drag, shallowing the dive), and the trolling speed.
For warmwater species — pike, muskellunge, walleye, largemouth bass — flatline trolling with inline spinners, shallow-running crankbaits, and soft-plastic swimbaits covers the top 3–4 m of the water column effectively. The Mepps Giant Killer, Musky Killer, and Bulldawg swimbaits are established producers for muskellunge in Canadian shield lakes. For walleye in bodies of water like Lake Erie or Saginaw Bay in Michigan, Bandit Walleye Deep crankbaits or Reef Runner 800 series baits track at 3–6 m on 10 lb test — the prime zone for spring and early summer walleye.
Downriggers: Precision Depth Control
A downrigger is a reel of heavy wire or cable, typically 45–60 lb test stainless or nickel-titanium wire, with a heavy ball (3–8 kg) at the end. The ball sinks to a precise depth shown on the downrigger counter, and the fishing line is attached to the ball via a release clip. When a fish strikes, the clip releases and the angler fights the fish free of the heavy ball. This system allows lures to be placed at exact depths — 10, 20, 30 m or deeper — with a precision impossible on flatlines or even parabolic lead-core lines.
Downrigger fishing is the backbone of Great Lakes salmon fishing. Lake Ontario and Lake Michigan charter operations targeting Chinook salmon (Oncorhynchus tshawytscha) and coho salmon (Oncorhynchus kisutch) typically run four to six downriggers simultaneously, staggered at depths matching the thermocline position and the depth where baitfish — primarily alewife and smelt — are concentrated on the sonar. Ball weights of 4–6 kg allow fishing at 25–40 m even at trolling speeds of 5–6 km/h. The release clip's tension is set just above the drag threshold of the reel — a king salmon of 10–15 kg will slam the release cleanly; a light coho or steelie may only pop the clip after a few headshakes.
Planer Boards: Spreading the Spread
Planer boards — also called side planers or in-line planers — are flat-sided plastic devices that run to one side of the boat on a mainline tethered to a mast-mounted board or carried on a smaller individual pin. As the board tracks out at an angle, the fishing line attached to it via a release clip spreads sideways, often to 15–30 m from the boat's centreline. Multiple boards running simultaneously on each side create a spread that covers a swath of water 30–60 m wide, vastly increasing the footprint compared to straight-behind trolling.
Planer boards are essential for walleye and muskellunge in Midwestern lakes and rivers, and for steelhead in tributaries of the Great Lakes during spring. The Church Tackle TX-44 and Off Shore Tackle OR-12 are the most widely used individual in-line planer boards. For salmon trolling on large lakes, directional board systems — where a single large board on each side carries multiple lines — are preferred, as they can hold six or more lines per side at varying distances.
Speed: The Single Most Important Variable
Ask any experienced trolling captain what single parameter matters most, and the answer is almost always speed. The lure's action — whether it wobbles correctly, whether a spoon rolls at the right rate, whether a trolling fly breathes and pulses as it should — is entirely speed-dependent. Most freshwater lures perform optimally in the 3–5 km/h range; saltwater trolling speeds for wahoo, tuna, and billfish run 12–18 km/h. A change of half a kilometre per hour can transform a dead lure into a productive one or vice versa.
GPS speed displays have replaced knot meters on most modern trolling boats, because GPS ground speed accounts for current effects that a propeller-based speed measurement misses entirely. Trolling against a current of 0.5 km/h at a GPS speed of 4 km/h means the lures are actually moving through the water at 4.5 km/h — a significant difference for a speed-sensitive presentation.
Building a Multi-Species Trolling Spread
A complete trolling spread for mixed-species Great Lakes work might look like this: two long downriggers at 25 and 30 m carrying dodger-and-fly combos for coho; two short downriggers at 10 and 15 m carrying spoons for chinook; two planer boards on each side carrying crankbaits in the top 5 m for lake trout or steelhead; and a flatline or two running spoons at 3–4 m behind the boat to cover any fish in the surface layer. Six to eight lines in the water simultaneously covering a depth range of 3–30 m and a lateral spread of 30 m on each side — this is serious production trolling.
The key to making it work without tangles is maintaining consistent boat speed and course, setting each line at a slightly different distance behind the boat, and pulling the inside lines first when a fish is hooked to avoid crossing them over the active line during the fight.
Saltwater Trolling: Wahoo, Mahi-mahi and Tuna
Saltwater trolling operates at higher speeds and with different lure categories than freshwater. Wahoo (Acanthocybium solandri) — one of the fastest fish in the ocean — are targeted at 10–14 km/h with high-speed lures and skirted natural baits, often rigged with a wire leader of 80–100 lb AFW wire to resist their razor-sharp teeth. Mahi-mahi (Coryphaena hippurus) respond well to medium-speed trolling of 7–9 km/h with naked ballyhoo rigs, skirted lures, or even artificial squid. Yellowfin tuna — one of the most prized catches in offshore sport fishing — are often targeted with cedar plugs, Williamson lures, or cedar-tipped offshore trolling lures at 8–10 km/h, with teaser/lure spreads designed to attract schooling fish to the surface.
Explore on the Map
Trolling hotspots span every ocean and major freshwater system: Lake Ontario for king salmon, the Finger Lakes for lakers, the striper-rich waters of the Chesapeake Bay, the wahoo grounds off Bermuda, the giant bluefin corridor south of Nova Scotia. Browse the map to find productive trolling waters by species and region, and build your trip around the seasonal patterns that put fish in the spread. The map is the navigator's companion for planning your next trolling adventure on any water in the world.