Availability on the Aquatic Menu

by Ron Newman

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Restaurant menus will often include limiting statements such as 'subject to availability' or 'when in season'. The aquatic menu for Rainbow Trout has these same restrictions. Various aquatic bugs are only available or in season at certain times. Availability will vary with the type of bug, elevation, weather, geographic location and numerous other factors.

Fly fishers should try to imitate bugs during their prime periods. This isn't essential since almost any fly can catch a fish at almost any time. However, the truly excellent fly-fishing occurs when the trout are taking a certain bug and the fly in use represents that bug. Knowing when to expect those bugs and using a fly to match can significantly improve your odds for some really great fishing.

For the southern interior of British Columbia, the following should provide some guidance as to when you can expect the seven most important bugs to be available on the aquatic menu.

Caddisfly (Sedge):

• Caddis Larva: Caddisfly larva in their cocoon-like casings are available throughout the fly fishing season. However, while in their casings these are not usually a preferred food source of the Rainbow Trout unless all other foods are scarce. This only seems to happen occasionally during the very hot periods.
• Caddis Pupa & Adult: In their pupa and adult stages, Caddis are the third most important source of food for our trout. Hatches begin about the first week in June. The frequency and quantity of hatches increase until they peak in the last week of June or the first week of July depending on elevation. Thereafter hatches steadily decline for the remainder of the season. The last major Caddis hatch is the Cinnamon Sedge in early September. Hatches happen throughout the entire day but evening and after dark are the primary times for emergence.

• Chironomid Larva: While in their 'mud tubes', Chironomid larva are not readily available to the Rainbow Trout. However, on occasion the larvae leave these tubes to crawl among the bottom substrates. This is the time of larva availability and it happens primarily in the spring or late fall and generally during daylight hours. At these times the larva are often bright red and known as "Bloodworms" but they also come in cream, green and other colors.
• Chironomid Pupa & Adult:Chironomid pupa are the second most important source of food for our trout. Various species of Chironomid hatch whenever there is water free of ice. The quantity and frequency of these hatches peak from May 1st through June 15th. The early spring and late fall hatches are mostly the smaller species while the larger species tend to hatch during mid-season. The majority of hatches tend to occur at mid-day as opposed to early morning or late evening. Adult Chironomid are sometimes taken by trout as they skim the water surface laying eggs (dry flies). In terms of adult availability, the best advice is to simply to watch for the times when trout are taking these.

• Starting soon after ice-off, small to moderate sized Damselfly nymphs will migrate from the deep water where they hibernate into the shallow water feeding grounds. During the second or third week of June the grown (and larger) nymphs will have their main hatches. Hatches occur during daylight hours and imitations should be fished accordingly. After the hatches, from late July through September, Damselflies nymphs are generally scarce although adults are abundant. In the late fall (October through November) the newly hatched nymphs have become large enough for the fly fisher to imitate and the trout will readily feed on these as they migrate from shallow to deep water in preparation for winter. The trout seldom feed on adults.

Dragonflies:

• Although adult Dragonflies are seldom a preferred food source for Rainbow Trout, the nymphs are the fourth most important food for our interior trout. These nymphs are available throughout the season. Availability begins at or shortly before ice-off as the nymphs come out of hibernation and begin their spring migration from deep to shallow water. Fall migration from shallow to deep water is the second most important period of availability and this peaks through September even though the hibernation period is a few weeks away. Hatches peak throughout July (watch for the first adults) and this is the third most important time of availability. Dragonflies tend to be nocturnal and are more active in the evening or after dark. Hatches also occur after dark but the trout will key on these during the afternoon as they gather for the hatching migration along the drop-offs.

• Gammarus Shrimp are the most important food source for our trout. These are available throughout the year, even into winter after ice-on. The primary time to fish shrimp patterns seems to be when the variety of other foods are limited. At ice-off and during the hot spells of summer are quite productive for the fly fisher using shrimp patterns. However, from the beginning of September until ice-on the shrimp are at their peak as a preferred food by the trout. Shrimp are available at all times of the day but during the evenings they are generally more active than at mid-day.

• Mayflies are actively taken in both the nymph and adult phases throughout most of the season that is free of killing frosts. In early May and early June the Mayflies are most abundant. There seems to be four other lesser but important hatches. These are early July, early August, and early September and there is even a minor hatch peaking around the beginning of October. As a rule-of-thumb, watch for hatches at or near the beginning of each month. The trout primarily take Mayflies during the daytime and into early evening.

• Waterboatmen are found in feeding samples of trout during every month of the fly fishing season. The primary time of availability, however, is in the fall with flights peaking in September but continuing late into the season. A lesser but also important time of availability is during the spring from ice-off until mid-May. The Boatmen tend to seek shelter during the low light hours and so are more commonly available at mid-day.

Observation by the fly fisher is still one of the most important aspects in determining when the various trout foods are available on the aquatic menu. However it is important to remember the "Food Preferences of the Rainbow Trout". One of the most important of these considerations is to match a NEW hatch. Fish imitations of aquatic foods that are newly becoming available. Good fishing.

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