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Tweed BioBlog- Monday and Tuesday 22 and 23rd October: Past and Present

Monday 22nd October: At the Faskally fisheries lab library, following up various references and leads. Got one reference I’ve been looking for for some time, to the fact that in the past it was widely thought amongst anglers that natural reproduction of Trout and Salmon was very inefficient. The general view was that fertilization rates in the wild were low and therefore that hatchery reproduction was much more efficient. A strange view to hold, because in nature, nothing is inefficient, natural selection makes sure of that.  However, that was the view and I now know that it was some work in New Zealand, just before the War that disproved it and showed that actually, it was hatchery fertilization that was less effective than wild (which was close to 100%) . Other work in Britain, just after the War followed this up and showed it was the same here. This idea that fertilization and survival in the wild was poor was one of the reasons there was so much support for hatcheries in the past, so it came as something of a surprise then, when it was found to be wrong – however, I’ve come across anglers myself who still think this is the case, almost 80 years after the work that disproved it!

Tuesday 23rd October: E-mails in the morning then out with Kenny to set up the Peebles trap and then take samples of water and invertebrates from around the Gala Water, to give background information for the analysis of the trout fry samples we took earlier in the year. This is the Isotopes work we’re doing with Napier University, to find out where Trout fry in the Gala catchment have come from Sea-trout eggs and where from Brown-trout eggs.