The term “super hatch” has wound its way into common usage among anglers.  But what exactly is it that makes super hatches super and who decides?
 
In the long history of angling literature the term “super hatch” is a relatively recent phenomenon.  I first remember seeing it in the early 1970’s in Doug Swisher and Carl Richards’ book, Selective Trout.   They have a chapter called “Super Hatches” where they list the most important mayfly hatches for three regions of the country.  A quote from the beginning of this chapter perhaps best describes their idea:
In an attempt to keep the number of patterns to a minimum, we have devised the concept of “Super Hatches” for each section of the country.  Probably 80 percent of all fly-fishing to rising trout during a season would be to these insects.  So it is logical that we should concentrate on these hatches.
They then list the hatches and describe the patterns for matching them.  But other than producing most of the dry fly fishing action during a season, they don’t provide any more information about what makes these hatches “super.” 
 
Whether from Selective Trout or elsewhere, the term “super hatches” seems to have stuck, and has been used in many books and articles to denote hatches that anglers should pay special attention to.  Its meaning however has remained largely undefined.  In general when someone refers to a “super hatch” we tend to assume it produces “super” fishing.  But what stage of the hatch produces super fishing?  All stages, or just those that produce surface feeding?  Does it produce super hatches everywhere or just on a few local streams?  And does it produce super fishing for weeks or months or just a few days?  Dave Hughes and I where discussing these very questions on a long drive back from a fishing trip last spring.  Though I hate to admit it, Dave comes up with a lot of good ideas.  He was thinking of some way to rank the importance of hatches, and produced a list of characteristics that could evaluate the importance of hatches to anglers.  After a good bit of discussion we thought we had something that could really help assess the importance of specific hatches.  In effect we tried to define just what “super” means and doesn’t mean.

Key characteristics of a hatch

First, to truly assess the importance of an insect to anglers, one needs to identify the factors that affect the importance of insect hatches, and not just when they offer surface fishing but throughout their whole life cycle. After considerable debate Dave and I came up with eight characteristics that we felt most influenced an insect’s importance to fly fishers. We also devised a way to score these characteristics on a scale from one to five so we could compare the importance of different insects in a consistent manner. Here’s what we came up with.

The Eight Factors of Insect Importance

1) Distribution: Distribution refers to how large of a geographic area a particular species inhabits. Some species for example are locally abundant but rare elsewhere, while others are abundant across most of the continent. We felt that species distributed over a large area are overall more important because you will encounter them more often on different fishing trips. However, if you’re fishing in the area of a locally abundant species that species will be just as important as one with a large distribution. We developed scoring criteria for distribution as follows:

2) Abundance during emergence: This characteristic gets at how concentrated and available adults are during emergence. Some species for example might be quite abundant but never produce heavy concentrated hatches that stimulate a strong fish feeding response. Other species might not be that abundant as nymphs or larvae, but the emergence of adults is concentrated so there are large numbers available to fish at that time. Abundance during emergence is a key factor in producing good surface fishing opportunities. Scoring this characteristic is based on the abundance of adults during emergence as follows:

3) Emergence type: Different species have different types of emergence behavior that affects how easily fish are able to find and feed on them. For example, some species crawl out of the water to emerge into adults, which effectively protects them from feeding fish unless blown in by wind. In contrast other species emerge in the surface film in slow easy currents, and thus are extremely available to feeding fish and generally much more important for anglers to imitate. To score this characteristic we devised the following criteria:

4) Emergence time: The time of day emergence occurs is more of a factor important to anglers than fish. For example, fish still feed heavily on species that emerge at night. But those species do not offer much opportunity for anglers except for those nocturnal souls who are willing to fish all night. On a few desperate occasions I have fished in the middle of the night, sometimes with good results, but I still prefer those more convenient species that hatch in the middle of the day. Therefore we scored this characteristic as follows:

5) Emergence duration: The length of time hatches last (days vs. weeks for example) is both a function of weather and natural characteristics of a species. Some species, for example, have multiple emergence periods during a year, and thus offer more good fishing opportunities than those with one short emergence period. While this characteristic can vary from south to north latitudes it still seems like a useful factor in determining the overall importance of different species. Scoring criteria have been set as follows:

6) Nymph & larvae behavior/availability: Some nymphs and larvae swim readily while others burrow into the substrate. Such different behavior greatly affects how fish feed on them and how important they are for anglers to imitate. We scored nymph behavior as follows:

7) Emerger behavior/availability: This refers to the behavior of nymphs or pupae that are in the act of emerging. Some swim to the surface and are readily available, while others crawl along the bottom of the stream or lake to reach the shore before emerging greatly reducing their importance to anglers. Scoring is similar to that for nymph behavior:

8) Adult behavior/availability: Finally, the behavior of adults influences how fish feed and how anglers will imitate them. Adults that float on the surface a long time before flying, for example, will produce a lot more fishing opportunities than those that fly quickly off the water. (Note: Because mayflies have two distinct winged stages - dun and spinner - this characteristic can be broken into two separate categories for mayfly hatches, one for dun behavior and one for spinner behavior.) Scoring criteria is again similar to the behavior of other stages:

There they are, eight different characteristics that influence a species’ availability to fish and importance to anglers. When combined together a single importance rating score can be calculated. Granted rating these characteristics is a subjective process. There is little actual data that clearly determines whether one species should score a 5 and another a 4 for a particular trait. However, a lot of understanding about these different traits does exist and it is possible to make good estimates so that we can at least remove some of the mystery behind why some hatches are called “super” and others not. A couple of ranking tables have been included to show how they might look when completed. Apply these criteria to hatches in your area and see which ones you feel are most important.

A complete list of hatch rating tables for all western mayflies can be found in Rick Hafele and Dave Hughes book Western Mayfly Hatches.