Baetis Complex - Part II - BWO Behavior and Habitat

The Blue Wing Olives have been coming off regularly on the Truckee River and you need to check out Matt Coles blog and he'll give you some good insight as to fishing the BWO hatch. You can check out his weblog at www.gilligansguideservice.blogspot.com

With that said, here's Baetis Complex, Part II, Behavior and Habitat


The Baetis Complex or Blue Wing Olive mayflies are said to be the most important to the fly fisherman. Knowing the behavior and habitat of these mayflies can be most beneficial when you encounter them on your favorite stream. We often see BWO's in the eddies and soft water as we float the Lower Yuba and the Lower Sacramento River.

Baetis, BWO Nymphs

Nymphs for the Baetis complex are found in most flowing water habitats. In freestone streams they live in quite pools, slow eddies and even white water rapids, but are most common in shallow, sun-struck riffles where algal growth is most abundant.

Though the BWO nymphs are found in fishable numbers in freestone waters, these nymphs often reach their greatest abundance in gentle tailwater and spring creek currents. Our local Lower Yuba River has these elements and a good population of baetis nymphs, although their population is subject to seasonal scouring which can affect their habitat.

Behavior of the nymphs of the Baetis complex is predicted by their nature as being a member of the Swimmers group. Quick pulsing movements of the abdomen combined with flips of the tail propel them in short bursts of three to five inches. When they stop swimming they immediately cling to the substrate facing upstream. Their active behavior causes them to be a common component of stream drift. This makes them available to deep nymphing methods almost 365 days a year.

The Baetis complex nymphs feed on "diatoms" or small "detrial" material they scrape from the surface of submerged vegetation or rocks. The nymphs go through as many as 27 instars. The mature nymphs, those ready for emergence, are easy to recognize by their dark well developed wingpads. By turning rocks over and inspecting the nymphs you fins, you can predict with fair accuracy the likehood of a coming hatch. If you see the baetis nymphs with the darker colored wingpads, a hatch is probably coming up.

Baetis, BWO Emergers and Duns


To emerge a baetis nymph releases it hold on the bottom and floats or swims to the surface, drifting downstream with the currents as it rises to the surface. After breaking the surface film, the dun quickly bursts out of the nymphal cuticle. The dun normally leaves the surface immediately but on cold days they may float as long as fifty feet before getting airborne.

The surface film can be a substantial barrier for these tiny bugs, especially on smooth currents. Wind and broken water breaks up the barrier and makes their emergence much easier. When BWOs are hatching in calm waters many fail to make it through the surface film. The result is a high percentage of cripples, stuck in the surface film. When this happens at least some of the trout focus on feeding on them and will ignore the duns on the surface. The fish may refuse your best dun imitations and your best presentations. This is time when you need to fish emerger imitations.

As with most match the hatch fishing, observation is the most important tool in your bad of tricks. If you ever carry a pair of binoculars, this is where they really help. Watch the BWO duns as they float on down the current and when a trout rises and breaks the surface, check to see if the duns are still floating on downstream. If they are, theres a very good chance they are keying on the emergers and cripples.

Baetis, BWO Spinners

Seven to eight hours after emergence the duns molt to spinners. Mating flights usually occur mid-day, from late morning to early afternoon. After mating, females of many Baetis complex land on protruding rock and sticks and crawl underwater and lay their eggs. After laying their eggs they either crawl back up to air or they let go and are swept downstream and are often eating by awaiting trout. This submerged egg-depositing behavior is unique, among mayflies, to members of some of the Baetis complex. Again some and not all.

There are other species in the complex that lay their eggs on the open water's surface. The females soon die after all the eggs are laid.The trout will sometimes feed on the tiny transparent, empty hulls. This is a time when a spinner pattern may solve this problem. When fish are taking spinners it is often easy to overlook and not an easy portion of the hatch to solve.

You can pick up Dave Hughes book, "Western Mayfly Hatches" at Amazon books by going to the following link. It is where most of this information came from.

http://www.amazon.com/Western-Mayfly-Hatches-Rockies-Pacific

Baetis Complex - Part I - Blue Wing Olive Mayflies

Here in Northern California and as we head into the fall and winter it is time to get ready for the main portion of our blue wing olive season. This is an over view of the Baetis Complex, or in common terms the Blue Wing Olive complex, that we will encounter here in Northern California and in the west.

Family Baetidae

The Baetis group of mayflies represents the most complex family of mayflies. The Baetis are of the Swimmers group of mayflies. There are sixteen genera and more than 60 species of Baetidae that occur in the west. This is often referred to as the Baetis complex. It is considered by many, to be the most important of all western hatches. The BWO hatches are so diverse and can be so prolific that they cause more selective feeding, more often than any other insect group. This is why getting to know and understand the Baetis complex is so important.

The most important thing to remember is that fly patterns for one species of Baetis will be just as effective for the others. You will need to change the size and the color as you encounter the different species on the river that you find yourself.

Emergence and Distribution

The Baetis complex is a large and widely distributed group, found in great numbers in all of the western states. With proper adjustments in size and color of your imitations you'll be able to match any Baetis hatch. For the fisherman, knowing the identification to the Baetis complex level, is as much as you practically need to know. You will need to focus your attention on finding an appropriate imitation and then fishing it with the most productive presentation. It is more important to get to the business of fishing and not worry about which species it may be within the complex. In simpler terms, collect a sample, match size and color and get on to fishing.

The Baetis complex hatches can occur at anytime of the year, depending on the species, the geographic area and the current weather conditions. Most adults emerge in the winter and spring. The exact timing of the hatches depend upon the species and the water temperatures in the waters that they live. Because the Baetis complex is so large, you must study the hatches on your own home waters in order to predict the hatches with any accuracy. Here in Northern California, the BWO hatch is primarily a later fall, winter and early spring hatch. With that said, because of their abundance and diversity, it makes the Baetis complex, or Blue Wing Olive mayflies, important at one time or another, on almost every western river and stream.

The daily emergence times of the various species change with the season but are typically in the warmer part of the day. In early spring the hatch will be from early to late afternoon, when the air and the water are the warmest. Mid summer hatches might move towards morning, or more commonly evening, when the conditions are cooler. In the fall, the hatches move back towards the warmest hours, again occurring between late morning and early afternoon.

It is well documented that the Baetis complex hatches occur on cool, overcast and even wet and snowy days. On warm and sunny days, the hatch is often truncated into a brief period. On cloudy days you'll get a trickling hatch that can go on for two to four hours with trout up in the water column and feeding all that time. On a bright day the hatch will often be heavy, but last only a half an hour to an hour. On these days the hatch can be over before you realize it is going on.

Because of the small size of the Baetis complex, the hatches of these mayflies are often overlooked by fisherman. The fish rarely make this mistake. For some reason when you have hatches of Blue Wing Olives happening at the same time as that of a larger insect, the trout often ignore the larger meal and become selective to the Baetis complex. A lot of anglers make the mistake of fishing imitations of the larger bug and the fish are focusing on the smaller Baetis.

Some fishermen consider Blue Wing Olive duns to be the most important stage of this complex, but studies have shown that the nymphs are a consistent and important food item nearly every week of the year. Trout feed heavily on nymphs during the pre-hatch activity and can also become selective to spinners when they fall in abundance. Because of their small size, emerging adults are often trapped in the surface film during the transition from nymphs to duns. This is often the “feeding zone” that trout concentrate on. Ralph Cutter refers to this as the "killing zone". This is where having cripple imitations will be very effective. Feeding trout will often ignore nearby floating duns. You need to be aware of this multiple, masked hatch, and when this happens and have fly patterns to match emergers, duns, spinners in order to fish a Baetis complex hatch effectively.

Imitation

The one saving grace of the Baetis complex is the way you can reduce their complexity by considering them all one group. They can be matched with color and size variations of the same set of flies. One problem is the broad spectrum of water types in which they live. You need to carry patterns that float on riffles, others that combine flotation with a fairly accurate silhouette to fish on nervous, uneasy water and finally you'll need flies that show the exact form of the insect on water so smooth that flotation is never a problem.

The Baetis complex hatch, or the tangle of hatches, is where the use of the "one precise right fly" just doesn't work. If you read John Gierach's book, Trout Bum, he has referred to fishing the BWO hatch as the "progression" of a blue wing olive hatch.

As the day goes along, you might begin by fishing a Baetis nymph pattern down deep along the bottom because you know there are lots of them down in their habitat. Then you'll switch to the same nymph fished shallow. You'll begin to notice duns and some trout will start feeding on them and you can be successful changing to a dry fly. But sometimes the trout will get finicky and you'll notice they're taking cripples, so you'll have to change to an emerger. And so forth, right through to the late afternoon spinner fall.

So what John Gierach has stated is that if you stick with one pattern through a blue winged olive hatch, you'll deal with some trout but probably end up frustrated. If instead, you observe the different stages of the hatch and how things change as the hatch progresses, and change patterns as the fish do, you'll continue to catch trout throughout the hatch. That's the goal.

Summary

So, pick up a new flybox, or recycle an old one, and label it BWOs. Fill it with patterns that match the size and color of the BWOs on your stream or river. Fill it with, nymphs, emergers, duns and spinners. Make sure you have dun patterns for (1) riffles (2) nervous water and (3) smooth water. If you do this you'll be ready for a Baetis complex hatch where ever you roam.

I will follow up this article with 4 additional articles with specific information on the habitat, flies, and techniques for presenting flies for the Baetis nymphs, emergers, duns and spinners

You can pick up Dave Hughes book, "Western Mayfly Hatches" at Amazon books by going to the following link. It is where most of this information came from.

http://www.amazon.com/Wesern-Mayfly-hatches-Rockies-Pacific/dp/1571883053/ref=sr_1_1?ie=UTF*&s=books&qid=1287687533&sr=1-1

Fishing Report - Lower Yuba 10-13-10

I fished the Lower Yuba today with an old acquaintance and friend, Greg DeYoung. We both had commitments in the afternoon so we hit the river at day break and fished until about 1:00. We had planned on fishing from Parks Bar to Sycamore RV park but when we did our shuttle the gate at Sycamore Grove was locked.

The Sycamore RV Park is now owned and run by the Yuba County Park Department along with Hammon Grove. Well, all I can say is don't try this too early. We decided, rather than wait around and twiddle our thumbs, to go down to the Marysville Gun club instead, which is about another 2 miles plus or minus.

We ran into a local guide Dave Barbieri back at Parks Bar and he said they showed up and opened the gate a little after 7:00. So I guess that's the story. Don't try it before 7:00.

We rigged with a Pettis Egg, and BWO nymph to start and through the day used, Troutbeads, various Caddis nymphs, Hogans Military Mays, HBI nymphs, Hogans S&M nymph, Rubber Legs, Lafontaine Pupa. You get the picture.

We noticed right away that there were salmon in the pool at the put in and in the riffles around the Parks Bar Bridge. A fair number of them, which seemed to be headed up stream. There is a small redd area in the willows above the bridge but no salmon were staged on them. We had a couple of quick hits as we started downstream below the bridge and hooked a smaller rainbow but lost it right at the boat. So I considered we got the stink off the boat. Maybe not!

We saw a nice pod of salmon at a dropoff at the big rock face with the eddy pool river left about a mile down from the bridge. We got a solid take and a head shake right away at that droppoff behind the salmon, but that was it for that run. I couple of quick hits but no hookups.

One technique comment about fishing eggs at the droppoffs or behind salmon, it does seem like the set has to be pretty quick or they spit the egg out. You've got to stay pretty tight to your indicator and ready to set or keep in tight contact with the flies if tight lining.

The large run above the old island which we have heard referred to as "The Aquarium" had a few salmon in it but not many. The riffle below "The Aquarium" had a few salmon on redds.

One of the biggest spawning areas is to the north of the big island. At the head of the riffle there were probably 8-10 pairs of salmon on the redds and as we floated down the long riffle there were more but not in full swing as of yet. The rainbows seemed to be starting to stage behind the salmon but in my opinion not in big numbers as of yet. By the time we got to the big island the sun was up it was probably mid 80's and bright as can be. Fishing this riffle is definitely much better in low light conditions, early in the morning or on a overcast or drizzly day. I think the whole fishing situation will change as soon as we get some overcast weather and the fish feel a little more comfortable and less exposed. Sounds like pretty good reasoning anyway. Isn't that what fishermen do?

I guess I'm feeling that the best fishing right now, with this hot spell, is probably early in the morning and then later in the evening. I've heard that lower down the river the caddis have been coming off in the evenings and swinging soft hackles or dead drifting in the film has been pretty good. I haven't been able to get out and give that a go, dang it!

In summary, we had one of those days where we had numbers of downs with the indicator in the runs, hits when tight lining, fish on behind salmon at the head of the runs before heading up the riffles, fish on and lost getting them to the boat, activity but not many concrete results. Like I said maybe we didn't get the stink off.

Have some fun out there. We make sure we do!