Cobbler’s Brook, August

The first half of August saw temperatures reaching 35 degrees centigrade, weather which had been preceded by a long period of very low rainfall. Farmers across the country were concerned that drought was affecting their crops and the stress on the countryside was visible, with plants wilting and trees losing their leaves prematurely. Locally there was a fire on Holmbury Hill and wild fires were reported on heathland in other areas of Surrey; luckily all of these were contained but the damage to wildlife is clear. Water courses were also suffering and ponds and streams were drying up.

Most Ewhurst villagers will know of Cobbler’s Brook which meanders its way through the woods and fields of the parish. I am sure there are many local children who will remember playing Pooh Sticks from the foot-bridge crossing the stream in the woods. The stream is fed from three separate water-heads located on the greensand ridge, running south past Radnor Place Farm, then alongside Bramblehurst Farm, whence it goes under the Ockley Road and passes through the woodland before  making its way behind the polo ground and then eventually running into Vachery Pond on the Vachery Estate just south of Cranleigh.

The stream is characterised by distinctive meanders, where the flow of the water cuts deeply into the bank on one side and deposits the eroded material further downstream. Children visiting Sayer’s Croft Field Centre are generally taken on a pilgrimage to Cobbler’s Brook to study these features and measure the water flow. The water level of the stream fluctuates dramatically throughout the year and in the early part of August was particularly low, due to the lack of rain. As a result the flow was intermittent, with pockets of trapped water along the course of the stream; the current was sluggish and there were whole stretches where the riverbed was dry.

A couple of years ago we had similar conditions and a remarkable thing happened; walking over the bridge I saw four or five large fish marooned in the pool of water. They turned out to be trout and because we were worried about their welfare we contacted Surrey Wildlife, who duly put us in touch with The Environmental Agency. They sent a representative who said that it would be too difficult to move the fish and that it would be best to let nature take its course. He also added that there must be trout elsewhere in the stream and it is probably less easy to see them when the stream is full.

I was very surprised that such large fish were resident in such a minor water course but since have always kept my eyes open for any sightings. Until this month I have seen nothing and then, in the same spot, I saw two fish trapped in the water by the bridge. The problem they have is a lack of oxygen due to lack of water and flow; this was coupled with the very high temperatures over-heating what water was there. I could tell that these were very unhappy fish and yet there was nothing that I could do for them.

I remember being bewitched by the carefree happiness of Schubert’s Trout Quintet, which was played at school assemblies when I was a child. I imagined a babbling brook and the fish gliding past, as I sat on the river bank contemplating the romantic scene. As is often the case, Schubert based his Quintet on a song he had composed earlier and I was recently quite shocked to discover that the lyrics have a tragic conclusion.  Here are the opening lines of the poem translated, with the observer enjoying a serene moment:

I stood on the bank
And watched, in sweet peace,
The Fish’s bath
In the clear little brook.

Christian Friedrich Daniel Schubart

His ‘sweet peace’ is rudely interrupted  by the arrival of an angler who savagely hooks the trout and throws his body on the bank, ending with the narrator’s terrible agitation. Alas, the following day when I re-visited Cobbler’s Brook I saw a dead fish floating in the water and felt a similar sense of sadness. There was, however, a smaller trout still swimming and I hope that he may have survived.

Whilst I was watching the fish I became aware of an antediluvian looking creature skulking in the rocks and roots of the bank.  It was quite large and had lobster-like pincers; with a bit of research I found that it was a Crayfish and it seemed a menacing predator of the waters, coming out of its dark hiding place to take prey. I soon realised that there was more than one in the pool of water and witnessed a terrifying encounter between a crayfish and a trout. I think the fish had probably found young crayfish in a crevice and was intent on plundering this treasure: the crayfish had other ideas and the two creatures confronted each other, with the crayfish sending the trout into ignominious retreat.

There are two types of crayfish found in Britain, the native White Clawed Crayfish and the Signal Crayfish, which originated in America and was first found in our rivers in the late 1970’s, having been released from freshwater fish farms. As is the case with many introductions, the Signal Crayfish has thrived at the expense of the White Clawed species, which is now listed and protected. The decline of the native species has been caused, in large part, by Crayfish Plague, a fungus to which the Signals seem immune but, nevertheless, carry and pass on to White Claws. This was first recorded in this country in 1981, although it appeared in Italy as early as 1860.

I find the two very difficult to distinguish, particularly when they are in slightly murky water but my best guess is that Cobbler’s Brook is infested with Signal Crayfish. I did a survey along the banks of the stream and discovered crayfish presence in four out of six locations studied, suggesting that they would be found all along the stream. The crayfish have earnt the name ‘rubbish collectors’ as they scavenge the water for food of an eclectic range; the body of my poor fish probably ended up as a meal for crayfish. Later in the month, when the water level had risen and the flow increased, I was unable to find any. I will keep my eyes open and let you know if I see them again and I would be very interested in hearing from anybody else who observes them. They are certainly worth the effort of looking for, as they are a quite unique water creature. Mind you don’t fall in the water though, I nearly did on more than one occasion on the slippery banks! I have also seen a Grey Wagtail on the banks of Cobbler’s Brook this summer; these attractive birds have, according to RSPB records, extended their range into lowland England in recent years and can be seen near running water. They feed on ants and midges during the summer and will eat tadpoles in shallow water and also snails. These birds remain on the Red List and thus are a rare sight. The wagtail I watched flew along the stream and landed a couple of times on the flat shores, where it spent a while searching for food and displaying its characteristic tail wag.

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