The Crane Valley Partnership
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Posted by Ilse Steyl Posted on 2017-08-23

Crane Fish Report 2016

The 2016 report on fish surveys in the Crane catchment has been published by the Environment Agency. The full report can be downloaded.

Highlights of the report are:

  • Results suggest that fish populations have almost recovered from the pollution events that occurred in 2011 and 2013. The effects of two successive stockings of chub, dace, roach and barbel in December 2014 and December 2015, consisting cumulatively of in excess of 15,000 fish has no doubt assisted in this recovery.
  • Although density results suggest signs of recovery at Crane Park, biomass still falls some way short of pre-pollution levels, and is indicative of the fact that those fish present are predominantly young stock fish.
  • At both Hounslow Heath and Crane Park estimated abundance of minor species had returned to, or exceeded, pre-pollution event levels within a year. Booming populations of minor species may occur in response to a reduction in populations of larger cohabiting species, and the pressures from predation and competition that they may exert.
  • The increase in gudgeon which have not been stocked is particularly encouraging, whilst numbers of dace captured has increased significantly. For chub the large numbers of juveniles captured in 2014 were not replicated in 2015, however the total numbers caught significantly increased this year showing a healthy range of sizes. Roach numbers have increased from 8 to 109 individuals ranging in size from juveniles to large individuals of 258mm.
  • Barbel which have been stocked over the last two winters have not featured in any of our surveys. The habitat found within our survey sites is likely to be the main reason for this, with Hounslow Heath and Crane Park offering little in the way of cover, with areas of river providing greater depth of water and increased cover from submerged macrophyte beds and riparian vegetation likely to be sought out by the species during its juvenile life stage.