Story by Harvey Thommasen with Photographs by Nick Didlick

I am standing on the shores of a coastal stream, casting to a spot where fish are breaking the surface of the water as they slash at a school of out migrating pink salmon fry. As the line swings straight below me, I begin to strip it in with an occasional short, erratic twitch, in an attempt to imitate a wounded fry and trigger the instinctive, aggressive response of a feeding cutthroat trout.

I am rewarded with the slashing take of a 50 cm long cutthroat. Its silvery-white side glistens underwater as the fish twists to rid itself of the fly. There is a jump or two, and then the fish surrenders as I quickly reel it to the shore.

In the spring maturing cutthroat trout are beautifully spotted above and below the lateral line. Their olive-green backs and upper sides blend in wonderfully with the green/brown algae clinging to the rocks on the river bottom, and they have attractive rose-pink cheeks. The pink cheeks often lead to searun cutthroat being mistaken for rainbow trout. Unlike on rainbow trout, however, the pink flush on the cheeks of a cutthroat never extends down along the sides of the fish.

Along the inner edge of each half of the lower jaw was a brilliant orange-red streak - the feature which gives rise to the name "cutthroat trout". The streaks are thought to play a role in determining social rank among cutthroat . When cutthroat of roughly equal size meet one another under water, they will face one another, arch their backs, lower their dorsal fins, open their gills wide, and then lower the throat part so that the red streaks can be seen. If one of the fish is sufficiently impressed, the subordinate individual will leave and avoid battling with his or her opponent. If neither is impressed, they may fight to determine which is the superior fish.

Every flyfisher has their favorite fish, and mine is the sea-run cutthroat. On a good day, I know that they will take almost any kind of fly presented to them - Doc Spratley, Rolled Muddler, Epoxy fry, or a floating Tom Thumb.

But how much do we really know about searun cutthroat trout? Surprisingly little research has been done on this fish, despite the fact that it is such a favorite fish to catch on a fly. Last time I checked, no formal research had ever been done on sea run cutthroat trout in British Columbia waters.

This quiz should help answer some of the questions commonly asked about searun cutthroat:

1) When and where do sea-run cutthroat spawn in coastal streams?

Depending on the locale and whether the fish are early or late arrivals, the spawning period for anadromous coastal cutthroat trout can extend from December through to May. In Washington, Oregon, and southern British Columbia, the peak period for spawning is in February. In Alaska, and probably most of northern British Columbia, the fish generally spawn in April and May.

The first cutthroat moving back up a coastal stream from the ocean, are usually the fish that have spawned at least once previously. A few large cutthroat can be found in or near the mouths of some of the smaller tributaries by the middle of July.

In the Bella Coola River, for example, bright, lice-covered sea-run cutthroat begin to show up in the river system by the first week of September, and upstream migration peaks between October and November. Some individuals may spend part of the winter in the estuary, then enter the river during the winter or early spring.

Fresh fish have been observed in the river throughout the winter and early spring. In the Bella Coola system, searun cutthroat have been taken as far up as Stillwater Lake (96km from the ocean), but most of the spawning appears to take place in the lower part of the river.

Most spawning is believed to occur between March and June, but sexually mature individuals can appear as early as November, so that the spawning period may be longer than originally thought. A 1993 Cutthroat Study found that the main spawning period for the Bella Coola River, on B.C.'s central coast, was May 10 - 28.

Peak spawning varies from watershed to watershed, suggesting that each stream has its own specific stock. Less than 20% of all returning cutthroat are mature enough to spawn in any given year.

2) When does spawning occur during the day?

Spawning takes place during the day and night, typically over a 5 to 10 day period.

3) How many eggs does the average Sea-run Cutthroat deposit?

The fecundity of the female coastal cutthroat trout varies with size and age. Reports of numbers of eggs per female have ranged from 226 for a 20 cm long fish to 4,420 for a 43 cm fish. Values of 1,000 to 1,200 eggs/fish are reported for some Washington sea-run females ranging in mean length from 37 to 41 cm. Larger females produce larger eggs, and these become larger alevin, which have size-dependent advantages in growth and survival.

4) How old are spawning searun cutthroat trout?

Few female searun cutthroat mature sexually before age 4. Up to 84% of females returning to streams of the Olympic Peninsula, Washington did not mature until age 5. Other studies have shown that searun cutthroat in southeast Alaska do not spawn for the first time until age 5 or 6.

5) What percentage of spawners will return to spawn again?

The rigors of spawning are not as hard on sea-run cutthroat as they are on steelhead. A relatively high proportion of cutthroat survive their first spawning and, after resting in the stream for a few weeks to regain strength, drift back to the estuary in the spring, feeding along the way on salmon fry and insect larvae. In Sand Creek, Oregon, in the absence of a fishery, 39% of the sea-run cutthroat trout returned to spawn a second time; 17% survived to spawn a third time, and 12% returned a fourth time. In the Alsea River, Oregon, where there was an intense fishery, survival was reduced to less than 14% between first and second spawning.

6) When do cutthroat trout first head to the Ocean?

The majority of Bella Coola cutthroat spend three winters in freshwater before going to sea. Age one is the earliest and age six is the latest recorded age at which an anadromous cutthroat trout has smolted and migrated to sea; most smolt at age two, three or four, depending on the locality. About 14.7 cm (5.8 in) is the average size of most downstream migrants on the Bella Coola River system (range 6.7 to 23.7 cm). On most other systems smolt size varies from 10 to 30 cm, and average size of first time migrators is 8 to 9 inches.

A few cutthroat will make the spring migration to saltwater at one year of age, and an equally small percentage will reside in the parent stream until age four. But nearly 95% will move to saltwater in their second or third year of age; that is, after spending two or three winters in freshwater. Preliminary scale studies on the Bella Coola River sea-run cutthroat reveal that up to 12% are age two, up to 83% are age three, and only 5% are age four at smolting.

Seaward movement begins in some streams as early as March and peaks in mid-May in Washington and Oregon.

In one Washington stream that also is populated by steelhead, migration of coastal cutthroat trout smolts followed the peak of migration of steelhead smolts. In Alaska, migration is later and peaks in late May and early June, with additional surges in mid-June an mid-July. The seaward movement of migrants in one Alaska stream studies over several years occurred at night during moderate stream flows, and migration stopped during extreme high or low water. It appears that cutthroat smolts begin migrating downstream to the estuary under the cover of darkness, and the murky, warm water of spring freshet to begin a new life in the sea. On the Bella Coola River system, cutthroat smolts probably migrate downstream at night during April and May, when moderately high-water conditions prevail.

7) Do searun cutthroat travel as far out in the ocean as do steelhead?

No. Migrating smolts begin to form schools just before they enter the marine environment. These schools remain intact until the fish return to freshwater. In Alaska, cutthroat trout travel along shorelines as far as 70 km from their home streams but do not cross bodies of deep, open water as narrow as 3 km. In Puget Sound, limited returns from tagged wild fish
indicate that migration does not extend beyond 50 km from the home stream, and the fish, like those in Alaska, do not cross bodies of open water.

However, in seining operations conducted in three successive seasons (May to September each year) off the Oregon and Washington coasts and off the mouth of the Columbia River, sea-run fish were caught 3.0 to 31.5 km from shore.

The cutthroat feed aggressively on euphausiids, gammarid amphipods, isopods, three-spined stickleback, Pacific Sand Lance, shrimp, sculpins, anchovies, herring, insects and fish eggs.

8) How quickly does a searun cutthroat grow?

Most growth takes place out in the ocean. Typically the searun cutthroat's length increases 5 inches the first summer out at sea, 3 inches the second summer, only 1.5 inches the third summer, and just one inch or less in each of the next two years. Because of this gradual slowdown in growth, few searun cutthroat exceed 20 inches or about 4 pounds during their complete life span, although an 8 lb. searun was caught off Vancouver Island by a salmon fisherman.

Sea-run cutthroat reach maximum weights of 2 kg (4.4 lb) to 2.5 kg (5.5 lb), with the average closer to 0.5 kg (1.1 lb) - 0.7 kg (1.5 lb). Larger fish up to 3 or 4 kg are very rare.

A 50 cm sea-run cutthroat caught in the Bella Coola River would average 1400 gm = 3.1 pound, and would have survived 6 or 7 winters in the Bella Coola system.

9) Are the bright cutthroat caught in the spring, rejuvenated overwintering fish, fish fresh from saltwater, or spawned out fish heading back to the sea?

No one is sure. In Alaska, small numbers of mature cutthroat do enter some streams in May, but such behavior is rare. The evidence to date, suggests that bright spring fish are either spawned out fish that have regained their conditions rapidly (feeding heavily on fry) and are returning to the sea, or they are fish that have over wintered in freshwater without spawning and are returning to the sea.

10) What is the composition of the typical searun cutthroat population?

In an ideal system where 1,000 searun cutthroat are returning up the river every fall, the following composition would be typical:

Approximately 85% (850 fish) will be fish that are returning for the first time. Only 14% of these will be female spawners. Approximately 12% (120) will be fish that are returning for the second time. Approximately 83% will be spawning females. Approximately 2% (20 fish) will be fish returning upstream for the third time. All will be mature females. Approximately 1% (10 fish) will be fish that are returning upstream for the fourth time. Again, all will be mature females. (Females often do better at surviving to spawn repeatedly because the males fight for spawning rights, weakening themselves.)