What Warm Water Does to the Hatches.

How the weather affects our "Hatches."

Hatch Chart according to http://www.flyfishingconnection.com/springcreek.html

Hatch Chart according to http://www.flytyingstation.net/stream.html

As you can see the variance between the two hatch chart would signify two different things.  With the size 18 - 22 Little Blue-winged Olives already been a mainstay in our mid afternoon fishing for quite some time we can suggest two things.  One, that the weather has progressed our hatches a three to four weeks ahead of schedule according to the second hatch chart.  Another fisherman would suggest that according to the first hatch chart that we are almost six weeks ahead of schedule.  Regardless of what hatch chart you follow our air temperatures and water temperature have progressed our hatches well in advance and rivals none of what I can remember from previous fishing seasons. We first documented fishing this years version of the Little Blue-winged Olives as a hot fly as of February 21st, 2012.

Several factors are directly related to the maturation of a specific type of insect on your home stream.  Fisherman have come to grasp the sequence of what will hatch in our local streams but water temperature ultimately plays the most important part in determining when a hatch will occur.  Temperature fluctuation will affect an insects metabolism, growth and reproduction rate.  If the fluctuation is above normal (as it is now), the insects metabolism will usually increase.  If the fluctuation remains constant the emergence is more likely to occur earlier then normally anticipated (as we saw with the BWO's).


One phenomenal article written by Rick Hafele, entitled "Adult Emergence" recognized a study of the Baetis (Blue-winged Olive) and how temperature affected the duration of eggs hatching.  At 3°C, the eggs began hatching after 119 days and when held at 22°C the eggs began hatching after ONE WEEK!


He also extends how temperature affects different species of aquatic insects.  Some insects will remain dormant in what is called "diapause" until a specific temperature terminates this "hibernation" and initiates the insect to begin to grow.  This allows insects to all reach full maturity around the same time frame and create a fun hatch to fish.  


To end the blog for the day I'll post the highlighting factors of Rick Hafele's article on "Adult Emergence:"


"Temperature (water and air), light intensity (cloudy or sunny) and moon phase have all been implicated in day-to-day variations of emergence. Temperature is again the dominant player, but it is not always as obvious at it might seem (so what’s new!). For example, rising daily temperature is known to trigger emergence. However, for some mayflies it is not the temperature on the morning of emergence that is important. Instead it is the temperature on the morning 24 to 48 hours before emergence that seems to determine if emergence will occur or not on any particular day. Light intensity also plays a significant, but again varying role, in daily emergence. Some species emerge when light intensity is high, such as a bright sunny day, while other species prefer low light conditions for emergence. Species of the mayfly genus Baetis, or Blue-winged Olives, are a good example of species that prefer low light conditions. Their hatches are routinely heavier on cloudy overcast days than on sunny bright ones. Species of Isoperla, or Little Yellow Stoneflies, on the other hand, often emerge best on bright sunny days instead of cloudy ones. The time of year may also influence if emergence is heaviest on sunny days or cloudy ones, with cloudy days preferred more often during the summer than during the spring or fall. This is likely related to air temperature, as hot dry conditions reduces survival of most adult aquatic insects."


So with hatches being well ahead of schedule I would always carry around an assortment of flies for the next hatch, because you never know when it is going to happen.  Mother Nature works her wonders in an unsuspecting way, why not be over prepared!


Tight Lines!