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Barbel feminisation

No joking matter, unfortunately. The effect on roach was the subject of discussion some years ago (I believe it was the River Don that was highlighted) and, if it affects one cyprinid, it can affect all.

Given the level of sewage discharge into our rivers, especially during dry spells when the effluent can amount to a significant proportion of the overall flow, it could be a further factor in the low recruitment seen in many of our rivers.

There could be a short term upside in that females are generally the larger fish of our river species but that will not help when there is no breeding and the females eventually die.....

A potentially serious issue for our barbel and all our other coarse fish.


Dave
 
David Clewer said:
No joking matter, unfortunately. The effect on roach was the subject of discussion some years ago (I believe it was the River Don that was highlighted) and, if it affects one cyprinid, it can affect all.

Given the level of sewage discharge into our rivers, especially during dry spells when the effluent can amount to a significant proportion of the overall flow, it could be a further factor in the low recruitment seen in many of our rivers.

There could be a short term upside in that females are generally the larger fish of our river species but that will not help when there is no breeding and the females eventually die.....

A potentially serious issue for our barbel and all our other coarse fish.


Dave
Click to expand...

I was thinking the same Dave. Also, if the EA have acknowledged that there is an issue that requires some level of risk management (have we witnessed any?) I wonder if the actual impact is even greater than that suggested. Its one of those things that could be easy to dismiss and laugh off because it's not as tangible as predation when we are looking for answers to diminishing fish stocks and poor recruitment.

Quite troubling.
 
David. FYI

The first recorded asexual effects IMO related to roach on the river Loddon.

I have highlighted this a number of times in discussions.

It would be funny if it wasn't so serious. I have no doubt its something known for over 30 years. I have also no doubt that it has been ignored because of the need to sell off the water companies at maximum profit and minimum regulation.

Graham.
 
Joe Winstanley said:
Interesting thread.

There was certainly a lot of talk about roach feminisation in rivers such as the Thames and Trent in the 90's.

A quick search of Google and I came across this paper 'Roach, Sex, and Gender-Bending Chemicals:The Feminisation of Wild Fish in English Rivers'

Roach, Sex, and Gender-Bending Chemicals: The Feminization of Wild Fish in English Rivers

The conclusion alludes to a series of unknown unknowns.
Click to expand...

Interesting Joe, although the conclusion does seem to be (as does the paper in the link Lawrence supplied) that steroidal estrogens and alkylphenolic chemicals are most likely the major cause, aided and abetted by a few minor chemicals.

Bizarrely, the paper you linked to seems to suggest that the fish may be adjusting to this situation. I can only assume that the authors mean the fish have grown used to and thus happy with their new roles in their now lesbian society....because beyond that, I can't think how any degree of adjustment would permit a population of fish without true males to facilitate successful breeding could possibly survive. They would die with a smile on their faces though :p

Cheers, Dave.
 
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