Went on a short field trip with uni yesterday and visited this nice spot not too far away from Barcelona. Unfortunately invasive fishes were equally abundant as native ones although there were lots of both!
Squalius cephalus (young one)
Lepomis sp. Does anyone know which one?
July 30, 2008
July 30, 2008
July 30, 2008
I'd go with what came back from FB, I agree with the concerns that people have regarding their exact identity, best way would be to pop a few off and key them out (with DNA as back-up).
Is it known how Lepomis entered the Iberian region? Would be interesting to look at whether any hybridisation event took place before or after introduction.
First records seem to be from 1910 at Lake Banyoles (which we visited when you were over) for 'improvement of wild stocks'. Here's an extract from a 2001 paper which explains a little more:
"Often the introduction of one species produces the need to introduce further species. Following introduction of major predators into ﬁsh communities which are not adapted to heavy predation, the decline in native species is such that it has often been assumed to be necessary to introduce a forage species more closely adapted for life with the predators. In fact, the introduction and spread of major predators, such as the pike Esox lucius, largemouth bass Micropterus salmoides, wels catﬁsh Silurus glanis, Europea perch Perca ﬂuviatilis, zander Stizostedion lucioperca, created the need to introduce and spread forage species, such as gudgeon Gobio gobio, roach Rutilus rutilus, rudd Scardinius erythrophthalmus, pumpkinseed Lepomis gibbosus, bleak Alburnus alburnus, and white bream which are more closely adapted to survive alongside the predator.
A range of reasons are cited for introducing ﬁsh species for the 'improvement' of wild stocks. The major motivation is to introduce some element that is perceived as lacking from the fauna of a water body. This is usually termed to ﬁll a 'vacant niche' or some variant of this. Although not strictly in line with the niche concept, which sees the niche as a property of the organism, the idea of a vacant niche is used to describe the perception that there are resources within a water body which are not being used eﬃciently for lack of a suitable species. It usually applies in Spain to new habitats such as reservoirs or regulated rivers, where the native fauna lacks elements competent to establish themselves in the new water body."
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