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Otter friend or foe


cannibalspinners

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Does anyone know how much otters can weigh

Someone said in an earlier post they eat a fair bit of fish everyday

Maybe they do more harm to fish stocks by eating the small ones

& not so much the big healthy adults

it may be a case of

If there is No small fish then there will be no adult fish

One day

what came first Chicken or the Egg

My point is

do otters do more harm eating mature fish

or young fish ,

Not getting my point across very well I KNOW :wallbash:

See post 191 for weights.

 

A dog otter eats approximately 1kg of fish a day.

 

As for the size of fish and predation dynamics let's put it this way. An otter usually eats smaller fish i.e. <1lb in weight. Of those fish he may well be taking adult fish such as minnows, gudgeon, bleak etc. fish that are generally numerous and found in large shoals. If they eat young larger fish, say roach, dace, chub, perch, trout, salmon etc. they are taking the 'designed for' surplus. (brown trout lay approximately 900 eggs per lb of body weight, salmon 5-700, grayling 3-4,000! etc. coarse fish are just as, and sometimes more prolific.) to put it in simple terms, each pair of fish of a given species need to produce ONE MALE AND ONE FEMALE DURING THEIR LIFETIME to perpetuate the species (allowing for no migration, immigration, predation etc..).

 

Obviously, a watercourse with clean water, gravel and weed growth with associated abundant invertebrate life will provide the requirements for excellent fish growth and egg survival. Alter those parameters by ...let's say introducing a non-native species that eats the weed and you have lost the spawning requirements for a whole host of fish. Agricultural or development practice that alters the substrate, such as runoff causing siltation of gravel beds does the same.

 

So, to put it in a nutshell, a healthy river with an established head of fish will provide more than adequate prey for a native apex predator that has an enormous individual range.

 

It's when we start messing with things that it starts to go wrong. For many years, the EA, Natural England, conservation volunteers and many, many other groups (including angling clubs) have spent lots of time and money in improving water quality and riverine habitat for fish, invertebrates, birds and mammals.

 

Unfortunately, less knowledgeable people have been filling artificial ponds on flood plains and gravel pit workings with non-native species or species not native to the local river catchments for decades. This is when an imbalance can occur and can impact on the whole chain of events very rapidly...with disastrous results. This is when it is possible for predator/prey balances to become biased.....also when predators can learn to find a high protein, easy to catch food source trapped in a stew pond!

 

There are no natural reasons that make the otter a foe. Only Man's interference (usually for money, often out of ignorance but frequently because of both) alters the habitat and ecological balance so dramatically and so quickly.

 

Look no further than the mirror to see the problem predator!

Eating wild caught fish is good for my health, reduces food miles and keeps me fit trying to catch them........it's my choice to do it, not yours to stop me!

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See post 191 for weights.

 

A dog otter eats approximately 1kg of fish a day.

 

As for the size of fish and predation dynamics let's put it this way. An otter usually eats smaller fish i.e. <1lb in weight. Of those fish he may well be taking adult fish such as minnows, gudgeon, bleak etc. fish that are generally numerous and found in large shoals. If they eat young larger fish, say roach, dace, chub, perch, trout, salmon etc. they are taking the 'designed for' surplus. (brown trout lay approximately 900 eggs per lb of body weight, salmon 5-700, grayling 3-4,000! etc. coarse fish are just as, and sometimes more prolific.) to put it in simple terms, each pair of fish of a given species need to produce ONE MALE AND ONE FEMALE DURING THEIR LIFETIME to perpetuate the species (allowing for no migration, immigration, predation etc..).

 

Obviously, a watercourse with clean water, gravel and weed growth with associated abundant invertebrate life will provide the requirements for excellent fish growth and egg survival. Alter those parameters by ...let's say introducing a non-native species that eats the weed and you have lost the spawning requirements for a whole host of fish. Agricultural or development practice that alters the substrate, such as runoff causing siltation of gravel beds does the same.

 

So, to put it in a nutshell, a healthy river with an established head of fish will provide more than adequate prey for a native apex predator that has an enormous individual range.

 

It's when we start messing with things that it starts to go wrong. For many years, the EA, Natural England, conservation volunteers and many, many other groups (including angling clubs) have spent lots of time and money in improving water quality and riverine habitat for fish, invertebrates, birds and mammals.

 

Unfortunately, less knowledgeable people have been filling artificial ponds on flood plains and gravel pit workings with non-native species or species not native to the local river catchments for decades. This is when an imbalance can occur and can impact on the whole chain of events very rapidly...with disastrous results. This is when it is possible for predator/prey balances to become biased.....also when predators can learn to find a high protein, easy to catch food source trapped in a stew pond!

 

There are no natural reasons that make the otter a foe. Only Man's interference (usually for money, often out of ignorance but frequently because of both) alters the habitat and ecological balance so dramatically and so quickly.

 

Look no further than the mirror to see the problem predator!

 

Excellent ,Just the answer i wanted

150_brown_trout1.jpg RECORD RIVER CAUGHT BROWN TROUT 7LB 5OZ

http://www.spinningluresuk.com

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Excellent ,Just the answer i wanted

 

I'm not having a got at you cannibal but please don't accept an answer just because it's the "answer that you wanted". This is how confirmation bias get's a grip of you. It would be much better if you used Worms' answers as a basis for your own research. I am sure that Worms would heartily agree.

The problem isn't what people don't know, it's what they know that just ain't so.
Vaut mieux ne rien dire et passer pour un con que de parler et prouver que t'en est un!
Mi, ch’fais toudis à m’mote

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Look no further than the mirror to see the problem predator!
Dammit. Here's me thinking it was the Daily Mail ;)

The problem isn't what people don't know, it's what they know that just ain't so.
Vaut mieux ne rien dire et passer pour un con que de parler et prouver que t'en est un!
Mi, ch’fais toudis à m’mote

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I'm not having a got at you cannibal but please don't accept an answer just because it's the "answer that you wanted". This is how confirmation bias get's a grip of you. It would be much better if you used Worms' answers as a basis for your own research. I am sure that Worms would heartily agree.

Assumptions unlimited but may I suggest it was with regard to the figures as opposed to the final answer?....Just trying to be diplomatic...makes a change B)

Eating wild caught fish is good for my health, reduces food miles and keeps me fit trying to catch them........it's my choice to do it, not yours to stop me!

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Cannibal,

 

See, you even have the "experts" disagreeing.

 

Worms suggest FAR more fish than any scat tests I've seen produce. On average, river otter in the summer can or do eat 2.2 lbs daily. 13% of their diet consists of fish. That's a max. In the winter, while I don't remember from the first 100 or so posts, it was something like 1.5 lbs. That's pounds not kg.

 

Phone

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Cannibal,

 

See, you even have the "experts" disagreeing.

 

Worms suggest FAR more fish than any scat tests I've seen produce. On average, river otter in the summer can or do eat 2.2 lbs daily. 13% of their diet consists of fish. That's a max. In the winter, while I don't remember from the first 100 or so posts, it was something like 1.5 lbs. That's pounds not kg.

 

Phone

Phone. Our rivers don't have the same head of crustaceans in them as yours' do. The favourite food of out otters, when they can get one is eels. An otter doesn't waste much of an eel ;).

The problem isn't what people don't know, it's what they know that just ain't so.
Vaut mieux ne rien dire et passer pour un con que de parler et prouver que t'en est un!
Mi, ch’fais toudis à m’mote

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That is a common belief that frankly has no substance, Eels are on the menu but as to whether the Otter 'prefers' eels is not actually known.

 

 

In a survey 8 out of 10 otters who expressed a preference said that they preferred eels :bigemo_harabe_net-163::bigemo_harabe_net-163:

The two best times to go fishing are when it's raining and when it's not

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