In the latest – autumn issue of Pêche Mouche one of the authors inserted an article about fly-fishing for white fish. This is indeed an interesting alternative, in particular in months when both trout and greylings are protected (whole 3 long months in Luxembourg!). One of the fish mentioned is naturally the chub – it turns out that in the past many French fishers considered the chub to be in direct competition with the trout and killed every one hooked, leaving them on the bank (the meat is considered not to be very tasty). The author says their assumption about the chub competing with trout were false but, unfortunately, doesn’t present any arguments on which his own assumption was based. The issue is of particular interest to me as, especially this hot summer, I saw the whole lots of rivers completely dominated by the chub, with no sign of trout presence.
| 60 cm Alzette chub, how many little trout were in his stomach? |
I do not pretend to be an ichthyologist but I consulted one and read some articles on the web: the early conclusion is following: the chub can be and often is a menace to trout population. Let me cite you just one article concerning Irish waters:
Chub, a popular coarse fishing species in Britain, has already wiped out native trout on one of the most popular trout fisheries in Co. Westmeath. The problem poses such a threat to other trout waterways that the Minister for the Marine, Noel Dempsey, will next month introduce emergency legislation to prevent the introduction of chubb to Irish trout waterways.“
| Nice Sure trout, this one is rather safe from the voracious chubs |
Yes, both species compete for the same food and habitat and it would be probably naive to think they don’t affect each other. With the difference that chubs are much more tolerant to unfavorable environmental conditions and can survive even in a very polluted and warm water. I saw myself many trout ‘hot spots’ occupied by big hoards of chubs ranging from 30 to 60+ cm. No trout could penetrate there.
“When chub and trout are side by side competing for habitat, the chub will always win”
The question is now, how to deal with this situation? I don’t support killing the unwanted fish (i.e. chubs), apart from it, they are simply too numerous. A good starting point would be a solid research project evaluating the potential threat posed by the chubs in Luxembourg and monitoring it’s influence on other species. This, however, is only a dream, as mentioned in an earlier post, here even the most basic data are kept secret and there is no sign it could change in the near future. If no effort at all was taken to deal with gobbies in Moselle, what to expect?