Pipeline will help scientists study fish migration

A £400,000 pipeline between the Cut-Off Channel and the Wissey will help eels and sea trout move to and from their spawning grounds - and help scientists learn more about how these rare species and commoner varieties of coarse fish migrate around the Fens.

As well as connecting the two waterways, the hi-tech siphon is rigged with sensors which can tell when a fish which has been implanted with a special tag passes through it. As well as tracking devices, the pipeline also has infra-red cameras, allowing Environment Agency fishery officers to keep a watch on which species are using it.

The EA-funded project, paid for by efficiency savings within the agency, is the first of its kind in the country. Similar schemes are planned elsewhere, as the agency steps up its work to conserve rare species and monitor the health of our rivers.

"It's an all-species, all-singing and dancing fish pass," said Kye Jerrom, a fisheries technical specialist with the EA. "It's a massive project. It's such a significant site it needed something like this."

The pipeline (right...) was designed and built in Holland, before being shipped across to Stoke Ferry in sections. It has a series of baffles and pools inside, to ensure the flow remains negotiable for all species. It also has a special eel lane, which helps anguilla ascend on its way inland, where it spends its life before returning to the sea for the long journey to its far-flung spawning grounds. 

It also contains sensors which can detect PIT (Passive Integrated Transponder) tags. Around 150 fish have been caught and tagged as part of a special research project. The EA plans to tag a further 200 each year, to build up an ongoing picture of fish movements. So far roach, rudd, chub, tench, trout and eels have been tagged at Stoke.

Scientist Karen Twine, from the International Fisheries Institute at Hull University, is known as the Barbel Lady for her work radio-tracking barbel on the Great Ouse. The study showed that barbel in the river were not being predated by otters, but were declining because their spawning grounds were silting up.

Now she's shifted the focus of her research to the Fens, where she'll be keeping an eye on Eel 2, Trout 3, Roach 19 and other tagged fish, to monitor their movements as they travel from one part of the system to the other.

As well as the PIT tags, Karen said she'll be using acoustic tracking - along similar lines to her acclaimed barbel research - to learn more about what's going on in our rivers and drains. You can just about see the tiny tag in the picture.

While there are no plans to study pike at present, the PIT tags might just do so by default. For the gizmos should keep on working if Roach 19 happens to get eaten by one.

This is exciting, cutting edge stuff. Meet Kye and Karen and you can't fail to be impressed by their passion for their subject matter and their drive to advance our knowledge of how fish in our rivers and drains are faring.

There are hopes that similar siphons will be installed elsewhere - the next location which has been pencilled in is between the Ouse and the Relief Channel, at Denver. Maybe, just maybe, the future of our fisheries isn't quite as bleak as it's sometimes painted.

One thing's certain - we're going to find out a whole lot more about our bread and butter coarse fish, as well as rarities like eels and sea trout, over the next few years. 

Fens get off lightly - despite fish kill in the Delph

We've got off lightly this summer. Just imagine what the drought they were predicting a few short months ago would have done to some of our drains and rivers, caught in a perfect storm of farmers abstracting the maximum water to try and save their crops, as the system cried out for rain.

While water levels have recovered, there's water on the Ouse Washes where the recent heatwave's fueled an algal bloom and made sodden vegetation turn to rot.

Now that foul water's started to find its way into the Delph, where another crisis looms. EA workers saw dead and dying fish in the Delph around Welches Dam on Wednesday. They've heaved in peroxide and deployed aerators to try and boost oxygen levels. It looks like they've got there in the nick of time, but the devil's in the detail as they say.

For they reckon it's going to take another three weeks for the remaining water on the Ouse Washes to clear, meaning a lot more de-oxygenated water could find its way into the Delph. Both the Delph and neighbouring Old Bedford are prone to fish kills at this time of year.

So far, the Delph appears to be an isolated case - meaning the rest of the system may well survive what's likely to be a short-lived heatwave unscathed. Let's hope so, podnas.  

+++Click here for schematics and maps of the Bedford system.

Is it time to research Fens pike decline..?

It's great news that the EA is working with the pike angling community on an innovative tagging project on the Norfolk Broads. I just wish they'd do the same in the Fens.

We know that our pike population is changing too. While we all like catching big pike, there are one or two waters where smaller fish seem to have become thin on the ground. The worrying thing is what's going to happen when the bigger pike die off in these places.

We all have our own theories regarding what's happening. Mine is that pike no longer spawn successfully every spring on many of our waters in the Fens. This explains why the pyramid of pike sizes which you'd otherwise expect to see has become disrupted, leaving - in one or two extreme cases - waters with a dearth of small pike.

On run of the mill, bread and butter drains and rivers, you'd expect to catch more pike under 10lbs than over. You wouldn't expect to blank most times you went but catch more twenties than jacks.

Small pike should be more numerous, according to the widely-accepted pyramid theory. Another reason for this is that male pike rarely grow any larger than 10lbs. They are smaller than their female counterparts, because they spawn eye-to-eye with each other, the male's shorter length means its milt fertilises the eggs the female deposits during their nuptials.

On one water I fished, I watched pike spawning before the end of the season on an area of grassy bank which had been flooded to a depth of 18ins or more as the water level rose after heavy rains. Within a week, the levels had receded, leaving the spawn high and dry before it had hatched.

It's no secret our weather's changing fast. After one of the driest winters on record, we're experiencing one of the wettest summers. During those crucial few weeks around spawning time, levels should have remained fairly constant this year, hopefully meaning a strong year class in a season or two's time.

If two extreme cases cited above become waters where you get 10 runs a day but finish the season with just a handful of doubles and the odd battle-scarred twenty, this spring will have been the exception that proves the rule.

Some blame the burgeoning otter population for declining catches. Otters are far more numerous than they've ever been. Up until five years ago, I'd seen just two in more than 20 years of pike fishing.

Three or four years ago, I began seeing them on a water I was fishing regularly.  By the 2009/10 season, there were areas where you saw them every other time you went.

The otters could have been there all the time, of course, perhaps losing some of their caution as they became accustomed to seeing anglers. I say otters, because by the back-end of that season, I'd seen them sufficiently closely to identify at least two individuals, while on one occasion, I saw an adult otter and a kit together.

Otters are a high-risk issue for anglers. While the general public probably doesn't care too much whether the rules are relaxed when it comes to culling cormorants or goosanders, most would probably rather see otters than us on waters if it came to a choice.

Otters eat other fish, besides pike. While commercial fisheries have the option - albeit a costly one - of otter-proofing their stock with fences, this clearly isn't possible in the Fens.

The only way of otter-proofing pike stocks, to a degree, is ensure their spawning success, so there are enough fish to replenish those eaten. In parts of America, where pike are routinely eaten as part of the angling experience, they have an answer which may well be the way we have to go to preserve our own pike.

On some waters, spawning areas are carefully managed to ensure that pike can use them successfully. If the EA can spend tens of thousands on eel passes, or efforts to safeguard the sea trout which run up the Nar and the Wissey, why not look to pinpoint and preserve the pike's spawning areas.

A survey of barbel in the Upper Ouse, conducted using radio-tracking methods,  revealed that the siltation of spawning areas was the reason for their declining numbers. We know that pike are in decline across the Fens. Maybe it's time we threw a little science at the question, to find out why. 

Click here for more on the Broads pike tagging project.

Click here to find out how repeat captures show there are less pike than you think in the Fens.

Markings show there are less pike than you think

Going back through last season's pictures reveals that these two pike are one and the same.

The giveaway clue is just behind its pelvic fin - the mark like a reversed letter C, with a dot just to the left of it. If you look, you can see it in both pictures.

Pikes' markings are unique, just like our fingerprints. Go back through your pictures carefully - looking at pike you've caught at different ends of the season, or over longer periods of time - and you'll sometimes find a repeat capture or two.

This fish grew from scraping 20lbs in early October, to 23lbs by late February. When I first caught her, she was long and lean with a big head and not much behind it.

She packed some weight on in the meantime, when I think at least one other person I know had her out. Those five months weren't without the odd mishap.


The second time I caught her, she had some obvious damage to her scissors and someone else's trace in her. Neither proved to be fatal.

And if she mades it through the last few weeks of the season and spawned successfully, she might even re-appear this time around - hopefully a little larger.

Here's a close-up of the mark that gives the game away - the reversed letter C and dot.

Look carefully and you can see that they're quite clearly one and the same fish.

 

One thing we can learn from repeat captures is they sometimes show there are fewer specimen pike in a water than you might think if you just take catches on face value.

At least three of the twenties caught from this bit of water were actually the same fish.

What this illustrates is just how important it is to conserve them. Because there are a lot less of them out there than a lot of people would sometimes have you believe.

If you care about tomorrow's fishing in the Fens, look after the pike you catch today.