Sunday 25 October 2015

Not finding Nemo

There has been two great causes for celebration this month: 


Gatwick has retained The Wildlife Trust Biodiversity Benchmark Award for the 2nd year! A huge thank you is in order to all the people who have been involved, particularly our fantastic volunteers and the gang from Gatwick Greenspace Partnership.

Electrofishing with AES Europe
The other brilliant news is... the fish have finally been removed from Pond 3!!!

Pumping down the pond water for netting

Why so much fish-hate, you might ask? Fish are an important part of certain ecosystems to be sure, but when artificially introduced into land-locked ponds (particularly a pond which used to be breeding grounds for Great Crested Newts), they are unfortunately highly destructive, eating anything which moves, churning up the sediment and create a stagnant, lifeless silty pool.

These fish had possibly been introduced in Pond 3 back in the 90's, sometime after another restoration project. Before beginning the pump down, the nutrient levels in here were incredibly high and oxygen very low, plant life was nonexistent and so little else was surviving.

Over the past few years, the Projects department at Gatwick have been hard at work all over the airport, improving flood defences and increasing the water holding capacity of operational ponds. They brought in AES Europe Ltd to remove fish out of harms way; as a result we now have a list of fish species for many wetland areas of Gatwick, all contributing to our booming biological records database.

AES carry out fish rescues and relocations using a variety of methods, including electrofishing (the process of passing a weak electrical current through the water, stunning but not harming the fish). They captured hundreds of Common Bream, some huge Common and Mirror Carp, a handful of Rudd plus a couple of Perch; these were then removed by special license and re-homed.

Common Carp  (Cyprinus carpio)

For me, it's been a great opportunity to learn freshwater fish identification; Nina and Tony have been patiently explaining the subtle differences between closely related species and even how to recognise some hyrbids...

The top: Rudd, and below two Rudd x Bream hybrids

Mirror Carp and Common Carp (Cyprinus carpio)

Perch (Perca fluviatilis), always more fancy-looking when young

Swan Mussel (Anodonta cygnea) - not good for eating when its been stuck in a silty pond

River Mole, North West Zone (June 2015)

The team from Corby have been to some unusual places for fish rescues in their time, but being next to the taxiing aircraft was a new one for them. I've grown so used to it now that I tend to forget they are there!

Fish removal from an area to be de-silted. They were released straight back into the River Mole

I can hardly enter species records for an area where the individuals have just been removed from, so I'm only entering those which are released back onto the sites. Below are a few more of Nina's helpful records:

Common Roach (Rutilus rutilus)

From the top: Bream, Pike and Chub

A bloomin gianormouse Perch (Perca fluviatilis

A lovely big Pike (Esox lucius

I'm building up a nice database of fish identification snaps too:
Young Rudd (Scardinius erythrophthalmus) - yellow eyes, dorsal fin set far back

Reddish tinge to fins, tail fin blunt and squared off dorsal fin

Young Common Bream (Abramis brama)
Dull fins, very pointed dorsal fin and forked tail

Rudd x Bream (Hybrid)

Fins are intermediate between the two species; orange tinged, not as pointed as pure Bream

A big thank you to Tony, Nina, Darren and the rest of the AES team for all your help this past year (and your massive amounts of patience).

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