A Lower Thames Fish Survey

Subject: Re: A Lower Thames Fish Survey Thu Sep 15, 2011 8:13 pm

I was actually quite interested in the type of water that the different fish were found in, it's really no great secret that a weir pool is full of fish! Seeing it on the aerial photo was quite nice. But then I guess anyone could read a book to find that out too.
*Chub found in weir pool - shock*
*Carp found hiding under tree - revelation*
Laughing

Posts : 2152 Join date : 2010-01-21

keith, wot we stand for is making sure our river is better in the future

if we put on the forum, hydroacoustic data, topography, nettings, electrofishing information, etc etc etc, those chinese in their boat a few months back would empty certain areas overnight
one trawl with their net could be catastrophic

as explained earlier no-one, admin or myself has use of it for our own fishing
I thought making available your info by request, kept it in the public domain and allowed for it to be not given to the poachers

opinions as always folks

Subject: Re: A Lower Thames Fish Survey Fri Sep 16, 2011 11:39 am

Electrofishing is a quite technical, there are a lot of parameters needing to be considered before even conducting a survey. As a fully qualified electrofishing team leader i have carried out hundreds of surveys. Temperature and conductivity are measured so as to work out the correct voltage so as not to be harmful to fish. The more mineral salts in the water and higher temperature means the water would be highly conductive and therefore requires a lower output. When i was working in Scotland in the highlands the water there had very little mineral salts dissolved in it due to the geology of the area and so electrofishing in most waters was deemed ineffective as most fish reacted but not actually stunned. Two types are ofeten used a DC backpack and an AC generator ( bankside) DC is kinder to fish but as you can imagine low conductivity means a severe drain on batteries and the kits aint light.

Posts : 2152 Join date : 2010-01-21

pukka one chris, thanks buddy

Posts : 2435 Join date : 2010-01-28

Chris Daphne wrote:: Electrofishing is a quite technical, there are a lot of parameters needing to be considered before even conducting a survey. As a fully qualified electrofishing team leader i have carried out hundreds of surveys. Temperature and conductivity are measured so as to work out the correct voltage so as not to be harmful to fish. The more mineral salts in the water and higher temperature means the water would be highly conductive and therefore requires a lower output. When i was working in Scotland in the highlands the water there had very little mineral salts dissolved in it due to the geology of the area and so electrofishing in most waters was deemed ineffective as most fish reacted but not actually stunned. Two types are ofeten used a DC backpack and an AC generator ( bankside) DC is kinder to fish but as you can imagine low conductivity means a severe drain on batteries and the kits aint light.

Hi Chris, do you know the answer to the query about damage to fry? Are fish below a certain size harmed do you know?

Subject: Re: A Lower Thames Fish Survey Wed Sep 21, 2011 10:35 pm

FYI

http://www.fishingmagic.com/news_events/news/15376-river-thames-fish-population-survey.html

» EA Fish Survey Month
» Drought & the Lower Thames Operating Agreement
» Lower Thames Flood Risk Management Strategy
» Lower Thames Operating Agreement meeting 28th June
» Work to boost fish numbers in River Thames