BLUE WINGED OLIVES SERRATELLA IGNITA
It would appear that the habits of BWO”S are changing , from what might have been expected some years ago.
The appearance of Sherry Spinners and consequent egg stripping began this year in very early June , actually during the Mayfly season .
Very recently (late September) I had the opportunity to witness a large column of sherry spinners flying upstream ,many with attached egg balls, and later the same evening , a hatch of Duns take place.
I have also been informed by very good authority, that a similar occurrence took place in early October on a different Southern stream, where eggs at that location, were also collected for the laboratory.
As the BWO has always been associated with mid summer evenings (mainly July and August), for both egg laying and hatching, it seems that this extended behavioural pattern could provide some indication of its changing life style due to climate change.
How long these flights will continue into the Autumn is now being observed and noted and how widespread it is on different Wessex rivers.
Possibly the flight of sherry spinners during the late evening,which once common, could be changing to include other times of the day (or night) when anglers are not by the water to observe such activity.
Movements of this fly have also been seen early in the morning.
Eggs laid down in the river from June onwards have suffered a depletion in numbers.
Initially thought to be Crayfish attack, which may have accounted for some of the losses, other reasons are now suspected and investigations into the cause/causes ongoing.
A two year programme is the minimum needed to establish the best and easiest method of success.
Unfortunately there are no manuals or reference works to consult.
Some of the remaining slides have now been transfered to a new board /cage which will stop any further losses by predation but may not protect against other causes .A few of the slides have been returned to the laboratory after spending 3 or 4 months in the river, so that comparisons can be made to those left instream.
Water temperature here , unlike the river ,can be varied.
A minority of the “Farmed Eggs” in the river have possibly hatched already but the majority are now in Diapause and will stay in that condition until next Spring and rising river temperatures.
The water temperature is now decreasing significantly even with the combination of low level and “ below normal “ flow rates for September.
( Figures just released by the E.A. for the River Piddle)
At present ,the nymphs are becoming increasingly difficult to locate on the river bed.
The two photographs are of BWO eggs and magnified 100 times
The first ( courtesy, C.Blake), shows eggs taken recently from one of the local project slides . They are in Diapause and appear in form as we might have expected at this stage
The second ( courtesy, Dr. C Bennett ), illustrates eggs taken from his slides and shows other stages of development
A presentation regarding the “Farming” of BWO eggs will probably take place at the next RIVERFLY PARTNERSHIP conference in London next March
Hopefully this will encourage further interest and development in this field and invite greater participation
The organisation ( RFP ) needs support to flourish and is crucial to the “well being” of our rivers and their fly life
As most Fly fishermen know, particularly those in Southern England, the latter is decreasing at an alarming rate, and any help to reverse this trend must be welcomed
Could we be entering a new era where the phrase “ captive breeding of endangered species “ is taking on a whole new meaning in world of fishing ???
Perhaps in the next few years we will know
The Club is a private one, founded in 1877, of approximately sixty-four members and six Town Rod subscribers. The Club’s waters consist of about 12 miles of wild brown trout & grayling fishing in the main River Frome, River Cerne and River Piddle, together with attendant carriers and side streams. The waters extend both above and below the town of Dorchester and the Club employs a part-time keeper.
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