Coho in Surface Water off North Coast River Mouths

Coho salmon feed in the top metre of water off north coast river mouths from late July through September, most actively in the first two hours of a moving tide. They are not chasing the river. They are holding in the plume edge where salt and fresh water meet, and they take a surface fly or a small spoon when the light is low and the bait is stacked. The bite is shallow, short-lived and tied to the tide book more than to the calendar.

Why do coho rise to the surface at the river mouth?

Coho are sight feeders with a small mouth and a preference for small prey. Off the Skeena, the Nass and the smaller mainland streams, the bait in late summer is juvenile herring, sand lance and pink fry, all of it in the top two metres. The fish that feed on the surface are usually the three to five kilogram (six to eleven pound) class, the two and three year old coho that have not yet moved into the river. Larger mature fish tend to sit deeper and are less reliable on the surface.

Surface feeding shows as a slow roll, a head-and-tail, or a slashing take with no body out of the water. It is not the jump of a pink. When you see a coho roll within casting range, the fish is usually still there on the next pass. The window is narrow because the bait is pushed by current, and when the current slacks the bait disperses and the fish sound.

Anglers who fish moving water for trout in other systems will recognise the read: current seam, broken surface, a fish holding on the edge of the fast water. The same eye applies here, and a site like McCloud fly fishing covers that kind of reading in a river setting, which is useful background for anyone learning to see where a feeding lane sets up.

What tide and current put coho on top?

A flooding tide is the main driver. On the north coast the flood pushes clean ocean water toward the river mouth and stacks bait against the plume edge. The first ninety minutes of the flood, and the last hour before slack, are the two windows worth planning around. A big tide, four metres or more of range, moves more water and usually produces a shorter but sharper surface bite. A small tide, under two metres, spreads the fish and the feed over a longer period with fewer fish up.

Current matters as much as height. Coho sit on the seam where the river outflow meets the incoming salt, and they face into the current. A drift that crosses that seam at an angle, rather than straight down it, keeps the fly in the zone longer. Wind against tide kills the surface feed faster than anything else. A twenty knot southeast against a flooding tide chops the plume and the fish drop.

Where exactly off the mouth do they hold?

Three positions repeat. First, the outer edge of the visible plume, where the brown water turns green. Second, the tide rips over a shallow bar, often within a kilometre of the river mouth. Third, the lee of a point or a small island that breaks the current and holds bait. The Skeena mouth, the Nass estuary and the approaches to Prince Rupert harbour all show these three positions on a chart.

Depth under the fish is usually five to fifteen metres (sixteen to fifty feet). You are not fishing deep structure. You are fishing a moving edge in shallow water, and the fish are often within three metres of the surface. Marking bait on the sounder at that depth, with fish arcs above it, is the clearest sign to start casting rather than trolling.

What gear and presentation work on the surface?

A seven to nine weight fly rod with a floating or intermediate tip line covers most of it. Small sparse patterns in pink, chartreuse and white, tied on size 4 to 8 hooks, match the fry. A short leader, two to three metres, keeps the fly in the surface film. Retrieve in short strips with pauses. Coho often take on the pause.

On gear, a light spinning rod with a small spoon or a bucktail in the fifteen to twenty gram range works when the fish are up but not committed. Keep the lure high in the water column. A slow, steady retrieve with an occasional twitch out-fishes a fast one in cold water. Water temperature off the north coast in late summer runs eleven to fourteen degrees Celsius (fifty-two to fifty-seven Fahrenheit), and coho are active but not fast in that range.

When in the season does the surface feed peak?

The surface bite builds through late July, peaks in the first three weeks of August, and fades through September as fish move into the rivers. The peak tracks the return timing of the local stock, which varies by system. On the Skeena the coho run is later than the sockeye and pink runs, and the surface feed off the mouth often overlaps the tail of the pink migration. On smaller mainland streams the window can be two to three weeks shorter.

Weather sets the day. A high overcast with light wind is the best surface condition. Bright sun pushes the fish down by mid-morning. Rain that raises the river and colours the plume can shut the surface feed for a day or two, then improve it when the plume edge reforms.

Do you need a boat, and how do you fish it?

Yes, in almost all cases. The productive water is offshore of the mouth and outside casting range from the beach. A small boat or a guided charter lets you work the seam and reposition as the tide moves. Drift with the current, cast across the seam, and let the fly or lure swing. Motor back up and repeat. Anchoring in the current is rarely productive because the fish move with the bait.

Safety on the north coast in late summer is about wind and visibility. Fog is common in the morning and lifts by ten or eleven. Carry a sounder, a VHF radio and a tide book. Know the slack before you commit to a drift near a bar.

What should you log after a session?

Record the tide height and stage, the wind direction and speed, the water colour at the plume edge, and the depth at which you marked bait. After a season those notes show which combination of tide and light produces surface coho off your local mouth. That is more useful than any general rule, because the north coast has many river mouths and each one sets up its own seam.

The desk read the Fisheries and Oceans Canada recreational fishing notices and the Canadian Tide and Current Tables for the north coast, plus the standard charter practice reported out of Prince Rupert, for this entry. Verified 2025.