Quote:
Originally Posted by stevecurtis  Can our British wild fish stocks stand this predation or are we going to see some species in danger? |
British fish stocks are generally very high in most places especially commercial fisheries. Species such as carp, tench, bream, pike, roach, perch, barbel, chub exist in very high densities in a lot of areas most through stocking and management so are probably sustained at an unnatural level, which has negative impacts on other species of wildlife, but is possibly why otter populations are increasing in inland areas. Brown trout and sea trout are commonly farmed and stocked so are unlikely to be effected. Most British fish are not threatened or anywhere near threatened. Species such as
vendace which are threatened are not really effected by otter but instead the stocking of ruffe and roach into lakes where they exist. Species such as lamprey are not particularly threatened by otter as pollution and water quality are the key reason for their decline. So in answer to this, otters are unlikely to put fish stocks under pressure, in comparison to other far more damaging impacts. Habitat loss, habitat degradation and human influence are more of a problem to fish than otters.
Otters have a wide diet which consists of birds, amphibians, invertebrates and mammals as well as fish so they are not heavily dependent on just fish. In many ways otter predation on water birds is more of an issue than on fish in the UK. Otter diet varies considerably depending on the time of year, during the spring it can be over 50% amphibians, or late summer dominated by crayfish, in winter it can be dominated by ducks etc. Within fish species they do tend to predate the most abundant species within a water body they are not particularly specialist although they like eels and similar fish (in coastal areas). It is widely accepted that they will take what is most abundant and scarcer species make up far less of the diet, meaning they are unlikely to put a given species under significant pressure.
Otters impacting fisheries on a local level may result in financial losses, and I am sure the sight of a large partially predated carp at the side of a commercial fishery is not going to look good to the manger. However this is not going to put any species under threat. Interestingly otters have different impacts on different water courses depending on age structure of fish, but in all cases its rare that that they actually clean out a river resulting in a suppressed fish stock.
Quote:
Originally Posted by stevecurtis The British freshwater eel is already having a hard time and when the Otters start to eat large amounts of wild salmon |
This is not due to otters and persecuting otters for this is not going to solve any problems in the long term. The recruitment of glass eels back into catchments is severely depleted and a decline has occurred. Eels are quite difficult to survey and although a decline has occurred since the 70s it may not be as bad as some sources claim. Both eels and salmon are migratory species which have specific habitat requirements, are both vulnerable to development and both have a high commercial value. These are impacting on both species not otters. As I mentioned earlier they are not specialist predators and will not hammer a species to extinction. Although both salmon and eels do form significant parts of the diet at certain times of the year i.e. during salmon spawning. If otters were so dependent on either of these fish then their population would decline as well. A study on the River Dee stated that otters are unlikely to have an impact on spawning success of salmon. Especially considering most fish taken were males which had finished spawning and were exhausted or dead.
Quote:
Originally Posted by stevecurtis their going to come head on with very wealthy land owners. |
The answer to this is education, because in the long term otters are not going to have any significant impact on their income. If it was a fish farm it may be different, but there are ways to avoid otter predation.
Linear Mode
