Otters again

[Ian Crook]

Chris, why not??

The Eurasian Otter or Lutra Lutra is the breed which populates the UK!!!!!!!!!

 

[Craig Wood]

One thing i would like to ask everyone on here is this...What good or benefit to the river eco system has reintroducing the Otter done?..

 

[Ian Crook]

Craig,

The otter was never extinct in the UK and it would have re-populated all it's old haunts naturally, the interevention of various groups have simply speeded the process up so your question is really irrelevant..........just like asking how has not culling badgers improved the environment or what good would supporting the spread and survival of water voles do to help the river eco system.............

Or more relevant, what good has the introduction of Zander done, Barbel to western flowing rivers, etc, etc.........

I am sorry but, no offence intended, I didn't get the point of that post........

 

[Chris Jones]

One thing i would like to ask everyone on here is this...What good or benefit to the river eco system has reintroducing the Otter done?..

From many an anglers blinkered field of vision, nothing whatsoever. Through the eyes of the bunny huggers and the vast majority of the general populace, restored an indigenous mammal, that man almost wiped out, back to it's natural place.

 

[Chris Guy]

Ian, sorry but most of us know the facts re the Eurasian otter. The post did go on a bit. (c'mon you must admit that ;-))
Must admit I'm getting tired of this whole thread, the killers are here to stay, and we might as well forget specimen barbel fishing in most of the lowland rivers for the foreseeable future. So sites as this will ultimately suffer, as there'll be precious few great fish to report and talk about.

 

[Chris Jones]

there'll be precious few great fish to report and talk about.

Or maybe there'll just be a re-evaluation of what constitutes a great fish? Fish that many have considered run of the mill from some rivers have always been fish of a lifetime in others.

 

[Rhys Perry]

'Otter numbers have increased in recent years but there are still only around 8,000 otters in the UK and they remain an endangered species.' (International Otter Survival Fund)
Well that's amazing, from being almost extinct 25 years ago, then releasing approx 150 over a twelve year period, to a whopping 8,000 in twenty years!
And they're still endangered? Get away.

That's 150 on top of the numbers that were already there, which I'd imagine was a lot more than 150. Plus there's a little factor called exponential growth, even if you just count the 150 and increase their number by a quarter each year, for 20 years, you reach 13,000 otters. So 8,000 is not beyond the realms of impossibility.
8,000 not endangered? I guess your right, but that's only the opinion of a very biased group, most broad based conservation groups seem happy with otter numbers in the UK now.
Though I'm getting the impression your in the 'kill them all' camp, as they're spoiling your fun.

 

[Nigel Gray]

Otters don't live for 20 years so you number is nuts.

Sorry, too knackered to work it out properly taking into account average life span as a factor. It shrinks your total dramatically.

 

[Chris Guy]

Chris it's not just the big girls and boys that are getting munched, the otters have no preference.

We have terrible problems from so many quarters in the east of the country in our rivers. Otters were initially welcomed, but the mature fish in many rivers around here are nearly gone it's other animals who are on the menu now.

I know in some parts of the country they are being kept in check, but not round here.

For arguments sake. We all know that an otter will kill one fish or other every day of it's life. So say there are 8,000 otters out there. That's 8,000 fish or other animals every day, or to put it another way, 2,920,000 fish or animals every year. At a conservative estimate.

 

[Craig Wood]

Thanks for the reply Ian and no offence taken...If Otters numbers were improving naturally,then why the need to speed up the process?..That does not make any sense Ian..No offence intended..My point regarding what good has reintroducing Otters had on river eco systems is quite simple..Firstly how on earth can it benefit the Otter if the very food it requires is declining and will continue to decline on some rivers due to the mature fish population being eaten and succesion upon succesion of poor spawning years due to low numbers of mature fish..I Know its not the Otters fault and wouldent dream of harming them or indeed seeing one harmed..As someone has quite rightly pointed out theres nothing anyone can do except enjoy whats left and cross our fingers that things improve on some rivers otherwise it may turn out to be one gamble too many by people who should of known better..The truth is no one knows how many were reintroduced due to various groups who operated outside of NE and the EA etc but its all done now so no point in debating,moaning or any other desciption or term others want to see it as..Big Barbel will become Rare on some Rivers sooner than we all think but thats just the way its going to be and like many have said we are just going to have to accept that..

 

[Rhys Perry]

Otters don't live for 20 years so you number is nuts.

Sorry, too knackered to work it out properly taking into account average life span as a factor. It shrinks your total dramatically.

True, but if total numbers were/are increasing at a rate of a quarter each year, and then only on the 150 released(not including the ones already out there), then that's the figure you reach.
I also tried to work it out properly myself and got a bit lost! It was more an example of how large numbers can be reached by a small population than any real hard facts.
But I still think its possible, and its more like 30 years than 20.

I knew some git would pull me up on my numbers!!

Fair play

 

[Ian Crook]

Ian, sorry but most of us know the facts re the Eurasian otter. The post did go on a bit. (c'mon you must admit that ;-))

It was just a copy and paste, sorry some interesting facts I had not seen before though........

Craig,

The need to speed up the process is generally the realm of do gooders, without which I would imagine we would have been at this point 5 or so years later than we are..................

The point is we would have got to this point sooner rather than later and the undelying problem, i.e. reducing fish numbers in some species in some rivers would still have needed addressing.............otters just seem to be a convenient target at which we can rattle our sabres.

That way we can blame something other than ourselves for the decline.................

 

[Jim Foxall]

Otters

The Eurasian Otter is not classified as "endangered" any more, they are actually classified as "near threated"which is 2 categories above endangered, vulnerable being the next step down the list..........

Some more interesting facts:

The Eurasian otter live in a wide variety of aquatic habitats, including highland and lowland lakes, rivers, streams, marshes, swamp forests and coastal areas independent of their size, origin or latitude (Mason and Macdonald 1986). In Europe they are found in the brackish waters from the sea level up to 1,000 m in the Alps (Ruiz-Olmo and Gosalbez 1997) and above 3,500 m in the Himalayas (Prater 1971) or 4,120 m in Tibet (Mason and Macdonald 1986). In the Indian sub-continent, the Eurasian otters occur in cold hill and mountain streams. During summer (April - June) in the Himalayas they may ascend up to 3,660 m. These upward movements probably coincide with the upward migration of the carp and other fish for spawning. With the advent of winter the otters come down to lower altitudes (Prater 1971). In a study conducted in Thailand in Huai Kha Khaeng where the Eurasian, smooth-coated and small-clawed otters live sympatrically, Kruuk et al. (1994) found that the Eurasian otters used rapidly flowing upper parts of the river. In Sri Lanka the Eurasian otter was live in the headwaters of all the five river systems but not in the estuaries (de Silva 1996).

In most parts of its range, its occurrence is correlated with bank side vegetation showing importance of vegetation to otters (Mason and Macdonald 1986). Otters in different regions may depend upon differing features of the habitat, but to breed, they need holes in the river bank, cavities among tree roots, piles of rock, wood or debris. The Eurasian otters are closely connected to a linear living space. Most portion of their activity is concentrated to a narrow strip on either side of the interface between water and land (Kruuk 1995). Otter distribution in coastal areas especially the location of holts, is strongly correlated with the presence of freshwater (Kruuk et al. 1989, Beja 1992).

Within the group home range, shared by resident adult females, each had her own core area. Resident males had larger home ranges in more exposed parts of the coast which overlapped with other males and with at least two female group ranges. Male and female transients moved through group ranges, relegated to less favoured holts, habitat and food. In freshwater home ranges are longer for both sexes (Kruuk 1995). Erlinge (1969) suggested that males were hierarchical and territorial, influenced by sexual factors, while female ranges were influenced by food and shelter requirements of the family group. Green et al. (1984) and Kruuk (1995) found that adult males spent most of their time along the main rivers, whereas adult females occupied tributaries or lakes, as they did in Austria (Kranz 1995). Rosoux (1995) found no sexual differences in habitat utilization and considerable overlaps in range. Young animals usually occupied peripheral habitat, but Green and Green (1983) found differences between immature and mature young males, the later having access to all available habitat and the other restricted to marginal habitat, supplemented by visits to the main river when vacant, temporally or spatially. While males generally have larger ranges than females in the same habitat, sizes vary according to the type and productivity of the habitat, and methods of measuring ranges vary from study to study.

Like most Lutra species, fish is the major prey of Eurasian otters sometimes exceeding more than 80% of their diet (Erlinge 1969, Webb 1975, Ruiz-Olmo and Palazon 1997). In addition to fish a whole range of other prey items have been recorded in their diet in variable proportions. These include aquatic insects, reptiles, amphibians, birds, small mammals, and crustaceans (Jenkins et al. 1980, Adrian and Delibes 1987, Skaren 1993). In a study conducted in Sri Lanka, Silva (1996) reported that the overall diet of the Eurasian otters consisted of 81.2% of crab, 37.5% fish and 8.7% frog. In addition to these the diet also included small quantities of water snakes, birds, small mammals and insects.

The percentage of crab in the diet of the Eurasian otters in Sri Lanka varied from 72% to 85%, and fish from 25-31%. There was significant seasonal variation in the diet in different habitats. The relative importance of fish in the diet was significantly higher in the reservoirs and lakes than the rivers and streams. Crabs were more important to otters inhabiting streams than those inhabiting rivers and lakes. Crabs were eaten more than fish during the monsoon (de Silva, 1997). However, in Huai Kha Kheng, Thailand 76% of the spraint had fish, 64% amphibians and 7% crab (Kruuk et al. 1994). The Eurasian otter is capable of taking fish as large as 9 kg (Chanin 1985), however, many studies in Europe have revealed that the fish consumed by the Eurasian otters are relatively small with a median length of 13 cm (Kruuk 1995).

The Eurasian otter is largely solitary and the adult otters tend not to associate with other adults except for reproduction. The family group of mother and offspring is the most important unit of otter society. In Shetland, where several adult animals used the same stretch of coast, encounters between adults were rare (Kruuk 1995) and the species was strikingly non-social. Kranz (1995) found evidence of social group formation beyond the occasional associations of two or more family groups, which suggests that under some circumstances otters of all ages and sexes may form temporary mutually tolerant gatherings.

In most of its range the Eurasian otter is predominantly nocturnal (Green et al. 1984). The exception is Shetland, where otters were entirely diurnal (Kruuk 1995). Green et al. (1984) found that activity was largely circumscribed by the solar rhythm so that the duration of activity varied through the year with night length. The reverse situation was found in Shetland with activity restricted by the day length (Kruuk 1995). Some workers have found a break in activity in the middle of longer nights or days and single peak around midnight or midday in shorter nights or days, although up to four activity periods per night has been recorded. Kruuk (1995) links otter activity to that of prey species, with the favoured marine species more vulnerable in daylight and those in freshwater easier to catch at night. In coastal habitats, tidal patterns influence otter activity, with significant preference shown for feeding at low tide, both in Shetland and on the Scottish west coast (Kruuk 1995).

The Eurasian otter attains sexual maturity at around 18 months in males and 24 months in the case of females, but in captivity it is usually 3 to 4 years (Reuther 1991). They are non-seasonally polyoestrous (Trowbridge 1983), mating in captivity has been observed at all times of the year (Reuther 1999). The gestation period is approximately 63-65 days, the litter size varies from 1 to 5, and the life expectancy is around 17 years (Acharjyo and Mishra 1983).

Let's hope that they feast on the signal cray infestation and if they could polish off a few cormorants, even better

 

[David Maddison]

Just seen this in my local press -

An upsurge in otter numbers in parts of Yorkshire could be under threat due to a shortage of cash. Don Vine, a conservation officer with Yorkshire Wildlife Trust, said it's 3 year funding from a trust run by land fill company SITA UK comes to an end soon and there is no replacement lined up.
Mr Vine works on the banks of the River Aire between Bingley and Leeds helping to protect otter habitats and create new homes for otters. He said " Its fair to say we still need more funding to make sure the healthy numbers of otters we have at the moment remain sustainable.
A major survey by the EA has shown signs of otter habitation increased by 400% on the River Aire since the last survey of its kind in 2002.

 

[David Gauntlett]

It is true that there are quite a number of rivers in which the water quality has improved, but my guess is that most of this is down to Margaret Thatchers utter destruction of British industry many years ago, rather than anything done by the bodies employed at great expense to bring this about, though this might be a slightly harsh generalisation in some cases.

Either way, this may explain why the rivers in the north, the traditional seat of heavey industry and coal mining etc., are now looking relatively healthy, whereas the previously healthy rivers in the south, the chalk streams etc, are now showing the results of many years of neglect by the water authorities...probably neglected on the basis that they were of such good quality previously, that they could get away with abusing them.

Certain southern rivers which started to produce exceptionally large individual specimen fish over the last twenty years or so, be they roach, perch, barbel or whatever, were seen by some as being extremely healthy...until it was pointed out that they were in fact dying, and these large fish were the end of the line. With virtually no recruitment due to unsuitable conditions, and loss of other species to the same problems, the old'uns were left to grow on undisturbed, with food no longer competed for. Once otters or other predators consume those big old girls, there being little else to eat, the river is left in a relatively sorry way. The Bedford Ouse and the Wensum being prime examples of this.

The undeniable fact is that had the rivers been substantially improved before the reintroduction of otters, as they so desperately needed to be, with fish stocks inevitably rising to healthy, natural levels....then the increased numbers of these predators would have passed virtually unnoticed, the proper ballance being reached as nature intended. It was the timing of the thing that was wrong, not the reintroduction in itself. Had the time, money and effort expended on that operation been directed at returning the otters habitat to a fit state to receive them, and THEN the otters helped to return....it would have made an awful lot more sense, don't you think?

The current position (excuse the pun) with the Wye is a shining example of what an apparently healthy river, with seemingly huge fish stocks, is capable of. The otters at this time I gather, are having little effect....which is exactly as it should be. What the true situation is, whether there are underlying problems that will eventually come to light, remains to be seen...but I truly hope it will remain a success story to lead the way.

A true count of the number of otters now present in the UK is not possible, as the concerned bodies freely admit...the numbers being bandied about at present are only rough estimates at best. They do confirm however, that a number of rivers have now reached saturation point. I have even heard it suggested that it may be possible that some of the otters now out there have been raised in captivity in unnaturally close proximity to others, which may lead to them loosing some of their natural territorial, self limiting habits, perhaps now being able to live in greater densities than was previously possible. I have no idea whether it is in fact possible to alter natural tendencies in animals in so short a time....but it would be sad if it does turn out to be a fact....not least for the otters!

Cheers, Dave.

 

[Tony Rocca]

"It is true that there are quite a number of rivers in which the water quality has improved, but my guess is that most of this is down to Margaret Thatchers utter destruction of British industry many years ago"

Its true that Mags helped a bit but its far from that simple. The open sewer known as the Don for example was generally saved by one EA mans work over many years, Chris Firth........ he got a MBE for his trouble. Aire, Calder, Rother, Dearn, all followed.

 

[David Gauntlett]

"It is true that there are quite a number of rivers in which the water quality has improved, but my guess is that most of this is down to Margaret Thatchers utter destruction of British industry many years ago"

Its true that Mags helped a bit but its far from that simple. The open sewer known as the Don for example was generally saved by one EA mans work over many years, Chris Firth........ he got a MBE for his trouble. Aire, Calder, Rother, Dearn, all followed.

Now there is a man whose hand I would love to shake....gives you back a measure of faith in human nature doesn't it....and makes you feel more than a tad guilty for moaning while others are doing

Cheers, Dave.

 

[Ian Crook]

Similar is true in my old North West with the Croal, Irwell, Mersey, etc.........all were worse than open sewers with the level of highly toxic chemicals they carried 30 years ago, again the NRA and then EA worked tirelessly with local volunteer groups to tidy them up. I would guess the same is true of most urban rivers of old..........

The fact the otter's come back has been speeded up with man's intervention does not in reality hide the fact that the rivers need attention. The current state of our rivers has been brought about by our necessity to constantly have bigger, better and more in terms of housing. 60% of the greenbelt land which was set aside in the 70s to ensure towns retained decent rural land in between them has now been developed for housing, all these houses require water, sewerage and storm drainage, not for one but in most cases 3 bathrooms, how can our natural environment possibly stand a chance against that level of exponential growth and useage. We don't wash one car per familly any more, we wash 3 or 4!! All that waste and detergent going into the, in many cases untreated, surface water drainage system. Many homes have washing machines still plumbed into the, in many cases untreated, surface water drainage system rather than the sewerage system.........

Look at leisure, there are probably more leisure boats on our waterways than there ever were working boats, all spilling fuel, leaking oil, many with direct waste sea toilets!!

Otters would have got here pretty quickly without support over a 30 year period, the simple fact is we have done nothing during that 30 year period to improve and probably won't over the next 30 years..............the vast majority of the residents of this country simply do not care provided they have their luxuries.....that is what we are up against, not otters!!