Botany Bay is an area adjacent to Lavington Park in West Sussex of approximately ten acres, which lies within the South Downs National Park; it’s privately owned but administered by the recently formed Botany Bay Conservancy Community Interest Group, founded by Anne Dennig. The site comprises a chalk stream and wooded ghyll, a small area of meadow, some still ponds and a fishing lake used by the Portsmouth Services Fly Fishing Association (PSFFA). In short, it’s a small area of great natural biodiversity with a population of wild brown trout.
From the 1970s Botany Bay was used as a small fishery, with ponds created for growing out rainbow trout. The stream was blocked by a concrete barrier or small dam, from which water was taken through pipes to fill various man-made ponds for the fishery; more ponds were created in the stream below the dam and blocked with nets and corrugated iron. Despite the fish farm activities, a small population of wild brown trout survived within the stream but, without access to areas of gravel for spawning above the barriers, their numbers declined.
In 2004 the fish farm was discontinued, the area was left idle, with all the nets, pipework, concrete and metal remains. Later that year, in collaboration with Robin Bray of the PSFFA, the Project Group started to restore the area to its former beauty and biodiversity. The Group approached the Arun and Rother Connections project (SDNPA, Sussex Wildlife and RSPB) for general advice on the restoration of the woodland, meadow and still ponds but also for advice on improving the conditions for the wild trout within the stream. Robin Bray arranged for Andy Thomas from the Wild Trout Trust to visit and advise the team; he showed them the ideal spawning areas upstream and explained how to create a passage for the trout to move up to these areas.
First of all though, the team had to remove the entire old fish farm infrastructure blocking the stream and to break through the concrete dam which was a major obstacle preventing fish from reaching the ideal spawning area. This was carried out with help from the PSFFA and local volunteers. The team tried to break through the concrete dam manually, but efforts with sledge hammers and chisels made little impression on the dam so, with the support of the PSFFA, help was sought from Kevin Powell of Delta-K , an explosives technology company, to help reduce the size of the dam. Small charges were placed on the dam and the resulting blasts created cracks that allowed the rest of the central section of the dam to be cleared by hand.
To help with the clear up, Arun & Rother Connections (ARC) project (Heritage Lottery Fund) funded skips and the hire of a mini digger. River Keepers from the PSFFA took charge of the first working party, along with local volunteers and family members. Using the digger, many of the old fish farm structures were removed, filling skips with pipes, corrugated iron and metal poles. The level of one of the ponds was lowered and the banks that had been re-levelled by the digger were planted with willow whips and reeds. SDNPA Ranger Graham West also helped and the various work parties included students volunteering for the Duke of Edinburgh and John Muir Awards.
After the fish farm infrastructure had been removed the team set about creating a passage for the existing brown trout to migrate up stream. Four small steps were created in the stream leading up to the break in the concrete dam; in addition, with help from students (taking the John Muir Award and learning skills for their Countryside Management BTEC), hazel spiling was used to stabilize some of the banks, eight pinch points were put into the stream to create spawning areas and places of refuge for trout were made with woody debris as cover.
Since opening up the stream passage in 2014, there has been a gradual but marked increase in numbers of brown trout in the stream as well as in the lake; in addition, trout have been observed moving upstream to spawn and for the last three seasons there has been clear evidence of redds in the stream. A rough estimate (visually counted) of the numbers of wild trout present in the stream in 2014 was 6, whereas the present (2017) estimate is over 40 trout of varying sizes from an inch to 8 inches in the stream.
Improvement in the stream since 2014 can also be seen from the invertebrate monitoring results. Three of the Botany Bay Conservancy members were trained by Matt-Owen Farmer of the PSFFA, as part of the Riverfly Partnership Monitoring Scheme and they now carry out monthly ‘kick-samples’ to check on the invertebrate counts present in the stream. These surveys have identified the presence of all of the eight indicator species: freshwater shrimp, stonefly larvae, up-wing fly larvae (mayfly, olives, blue winged olive, flat bodied) and caddisfly larvae (cased and caseless). The monitoring gives a guide to the health of streams and rivers as changes to the water quality are reflected in the numbers of and different invertebrates present. The riverfly data scores have increased from 8 and 9 in 2015 to scores of 15 and 16 in 2017.
“In the lake, the increase in the number of wild brown trout has been quite impressive, and all the wild fish have been returned to the lake as part of the PSFFA catch and release policy for wild brown trout. The lake is only stocked with a maximum of 75 triploid rainbow trout up to 2lb in weight, in order to give the wild stock a fighting chance to grow and improve. The work carried out on the Lavington stream has played a major part in the increased productivity of the wild brown trout stock and further planned works will only improve the site,” said Steve Batten, Water Manager for the PSFFA.
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