otters galore

[Santiago]

As discussed in quite a few other threads, the reasons for the decline of fish in river is far more complex than the presence of otters per se. The main reason being pollution from agricultural pesticides! But you're point on naive fish is well made and has some truth because those fish don't see otters as predators. Even so, their progeny will, and in several years time more rivers will benefit from otters just like the avon does.

And they don't eat everything, certainly not in a destructive manner. Moreover, scientists have already shown that as otters spread they're pushing mink out, and helping to bolster water vole populations. That's just another example of otters being beneficial. They also eat loads of crayfish so enormously reduce predation of fish eggs. They evolved over millions of years to manage the ecology of rivers and as such will do a much better job than mankind. No contest!!

[Olly]

I am not being aggressive in any way - a simple statement anglers are not ignorant people.

Santiago has replied and although we may disagree on some things the point of naivety in some rivers of the otters presence by fish is agreed by both parties!

I just hope that there is some progeny to continue the species in the future!

[Santiago]

No worries Olly. It would be silly if we agreed on every thing. I amended my earlier post about most anglers being ignorant on freshwater ecology, so as not to sound inflammatory. As for recruitment, that's where we need to focus on!

[Olly]

I too have just amended mine! No offence intended!

[Liphook]

Hmnn the great otter debate! I'm happy to have otters present in our area but draw the line at the numbers of obviously hand reared 'imprinted' that have appeared overnight. Otters should naturally be shy. They shouldn't be seen in groups midday in a busy town. At one point coaches were stopping on a busy town bridge to let tourists take photographs. As an apex predator they should be present in low densities.

[Beresford]

They evolved over millions of years to manage the ecology of rivers and as such will do a much better job than mankind. No contest!!

Exactly this.

[Barbulus]

Not sure whether these links will work but if they do, TFF'ers might find them of interest ? (I don't think I am breaking any rules in this as they are in the Public Domain so referenced already).

There are always alternative viewpoints as we know and I am certainly not using these videos as Harvard Reference Points but they do provoke a thought that there are benefits that can accrue that might not be immediately obvious perhaps; whether an "apex predator" or rodent ...... and in case you wonder, the Devon related video is not me re-introducing the beaver locally down here on the River Exe although I can see a potential benefit to that ......

I have had the pleasure of visiting Yellowstone several times and, once only, seeing one of the wolf packs on a snow covered treeline as they looked down on a herd of Bison crossing the river. I found something very powerful and to be blunt, emotionally uplifting, seeing that "apex predator" in a wilderness environment and the next morning at dawn, armed with a 8 weight fly rod and wading a local river miles from civilisation is a memory I treasure. Of course, last year when an otter "popped up" on the River Avon in my swim one morning, it made me think why the swim was not just bewitching in its traditional English early misty morning beauty and particularly tranquil but, perhaps, the previously resident Chub had decided there was pressing fishy business elsewhere on the river that morning. Balance in all things perhaps ?

https://blog.nationalgeographic.org/201 ... ge-rivers/

https://www.youtube.com/watch?v=GUE7AST2L54

[Santiago]

A casing point. The ecosystem just off the Californian coast was not so long ago in decline, but has been saved by the reintroduction of sea otters. Kelp forests were being decimated by sea urchins which had grown to great numbers due to lack of otter predation. Nowadays, this ecosystem is now thriving with lots of fish that find safety in the kelp. The kelp thrives because the otters find the sea urchins an easy meal. Likewise, in the UK the otters find crayfish an easy meal, so sooner or later our rivers will benefit from their presence. And like all apex predators their numbers will eventually plateau or drop, depending on the amount of easy food available. But the idea that they're going to increase in population ad finite, and devour all fish from our rivers is laughable. They evolved to maintain sustainable stocking levels of fish, and one way they do this is be having a varied diet that is not solely fish based. Yet, of course they will eat naive fish! But the surviving fish will be fitter as will their fry, and there should be many more fry given the expected reduction of crayfish.

[Luga00]

Can the above example really be considered a 'case in point'? Surely the ecosystem off the coast of California can't really be compared to a small UK river or stream? Or maybe it can?

[Santiago]

I wasn't directly comparing the two very different ecosystems. Moreover, I was merely showing an example of otters acting as a cornerstone species, albeit in an ecosystem that is not representative of a small English river. Yet I do believe the main lesson learned in California can be transferred to English rivers to a reasonable extent ; especially since we have a plague of crayfish to deal with. Remember, our rivers have been a bit of a state well before the inadvertent reintroduction of otters, so it's highly unlikely that they're responsible for low fish stocks ; especially since they've been present for a long time in relatively productive rivers like the Hampshire Avon, where fish appear to thrive!