Get Down to the Salmon's Depth

To catch salmon, you must get a bait or lure to the fish's depth. Downriggers, weights or divers can all get you there. Here's how to use all of them and the advantages and disadvantages of each.

By Ray Rychnovsky

The first principle of catching salmon is, "Get your bait or lure in front of a fish." You can do everything else right, but until you get your bait or lure to the fish's depth, you won't catch one.

Anglers who use downriggers can crank their heavy weight straight down to get the correct depth, but these are cumbersome on a small boat, and many anglers do not have downriggers. Even with downriggers, some lines are usually fished with weights or with diving planes.

Most anglers who fish with light weights will guess what weight to use and how much line to let out to get to the right depth. Other anglers avoid this combination because they don't know how deep they are fishing.

When I was taking partial differential equations courses in college, I calculated the weight needed and the amount of line to let out to get to depth. The sidebar accompanying this story shows an example of these calculations and how to get to the proper depth with a light weight.

Mooching is a great way to catch salmon when fish are schooled. Mooching is letting the boat drift slowly with the wind and tides, and dropping bait suspended from a long leader beneath a light weight almost straight down to their depth. This is particularly effective when salmon are deep or when fishing from a charter fishing boat with lots of anglers. Lines go almost straight down, so you just let out more line to get very deep and you minimize tangles. However, when salmon are scattered, trolling will catch more fish.

Brad Lorens holds up a Chinook he caught while trolling aboard a charter boat off the California coast. Photo by Ray Rychnovsky

Trolling has always been a great way to catch salmon from private boats or small charter boats when only a few anglers are fishing. Tangled lines can be easily avoided by using different weights on lines, and trolling finds and catches fish whether salmon are schooled or scattered.

Trolling has one additional advantage for California anglers - you may troll with conventional barbless J-hooks. Drift moochers using bait (that fishing method is almost always with bait) off California's coast must use barbless circle hooks. Many anglers blame circle hooks for lots of missed bites and welcome the chance to use conventional hooks.

Most trollers use a 2- to 3-pound cannon ball weights on sinker releases. The weight is dropped when you hook a fish, so you play the fish without the hindrance of a weight. Still, heavy weights demand stout rods and a bit of manhandling.

For charter boat fishing, heavy weights take your line almost straight down and keep lines separated. With only a few anglers on a private boat or a six-pack charter, lighter weights are much better. They are easy to handle; you can use light sporting tackle, and you don't pay for another weight every time you hook a fish.

Before developing my research, we trolled for salmon with a combination of downriggers and lines with 2-pound weights on sinker releases. These lines went almost straight down, and we fished just behind the boat. We also used one line with a 6- or 8-ounce sinker, letting out 75 to 100 feet of line to fish far behind the boat. That line entered the water at a shallow angle, leading us to believe the rig was being trolled shallow. We caught a lot of fish on this outfit thinking these were stray, shallow fish. How wrong we were.

My calculations showed that we were fishing much deeper than we had thought. Fished with 100 feet of line out, this rig was almost 60 feet deep. Rather than being our shallow line, it often was our deepest line.

My book, The Troller's Handbook, has easy-to-read graphs showing how to get to the desired depth for many different line strengths, trolling speeds and weights. Just pick the depth you want to fish off the left scale of the graph and read the top scale to see how much line to let out to get to that depth.

If you are using a different line and weight combination or trolling at a different velocity (velocity is an important parameter), you can use the graph here and know you will be somewhat in error, or use graphs from The Troller's Handbook that resemble line strengths, sinker weights and trolling speeds you use.

These curves are for a weight and bait or small lure with only a little drag. If you add a high-drag device, such as a flasher, you will be pulling the weight back and up. This means you will be fishing shallower than the graph indicates.

As you change trolling speed, the depth of your lure or bait changes. Two mph is a good trolling speed for coho salmon, but a speed of 1.5 mph is a better speed for chinook salmon, and you will be fishing even deeper at the lower velocity. With 50 feet of line out, you would be 44 feet deep at a velocity of 1.5 mph - not the 37 feet deep at 2 mph.

To know how much line you have let out, you can count out one-foot pulls of line, pre-mark your line at intervals, use line that changes color every 30 feet and count the number of color changes or use a line counter reel like a Diawa 47LC to let the proper amount of line out.

Downriggers are great to get your bait or lure deep. You crank the weight down until the counter on the downrigger shows the desired depth, and you know you are fishing the correct depth. I like to use a small size 1/0 flasher between the bait and downrigger. I've found flashers work best by tying them on short leaders both from the downrigger weight to the flasher and from the flasher to the bait. Follow the recommended leader lengths on the downrigger package to get the right setup.

An alternative is to use bait without a flasher and let out a lot of line - like 50 feet of line - before you clip the line to the downrigger clip. That puts the bait far behind the boat, and it may catch fish that shy away from the vessel.

Another way to get down to the fish is with a diver rigged so the hydrodynamic force of the water takes the diver and your bait or lure to the desired depth. The graph of depth for divers is not the same as the one shown here for a weight but it is similar. A

s with weights, you are fishing deeper than it appears, and this graph will get you close to depth shown when using divers.

(EDITOR'S NOTE: Ray Rychnovsky has written three books. The Trollers Handbook, California Guide - Great Saltwater Fishing, and San Francisco Bay Area Fishing Guide are available at local bookstores, or contact Amato Publishing at (800) 541-9498, visit

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