Image source: shutterstock
Beautiful fishing spot – but what danger lurks around here for fish?
Marauders are ravaging our rivers! Fish stocks are depleted, and river ecosystems are suffering. Quite simply, there are too many mouths to feed and not enough fish.
But who is devouring all the fish? Where did they come from and what is being done to minimise their impact? We take a look at six of the most infamous predators and the problems they’re causing for anglers.
Cormorants may only eat what they need to survive, but survival means a significant diet! They feed on at least a pound of fish a day, which they catch with their long, hook-tipped bills while swimming underwater.
Historically, cormorants have been controlled through pesticide pollution and persecution, but that changed after Denmark and Holland introduced protective legislation in the 1960s. The British Trust for Ornithology explains how:
‘The European population increased rapidly and continental birds started to extend their wintering range into Britain & Ireland.’
Before 1981, you would have found cormorants breeding mainly on the British coast. But when one tree nesting colony established itself at a reservoir in Essex, others followed. By 2012, they were breeding at 89 inland sites in England! Numbers have risen ever since, and it’s estimated that 30,000 birds come to the UK every winter.
Why does this increase in population matter? Because cormorants are a real threat to fish stocks. A survey by Swansea university found that they are causing a problem for most fisheries. In fact they’re considered to be more of a threat than mink or otters.
Cormorants favour medium sized fish and often leave damaged victims on the bank if they can’t swallow them. Martin Harper for the RSPB paints a vivid picture:
“To a cormorant, an angling lake stocked full of fish is much like a bird table to a blue tit – a feast to be harvested.”
There’s no easy solution either. Cormorants are protected under the Wildlife and countryside act 1981. However, thanks to three years of campaigning by the Angling Trust, it’s now to simpler to apply for a license to shoot cormorants that are causing major problems.
This streamlined swimmer originally came from Nordic countries to over winter in Scotland, but since the 1970s, they’ve spread throughout England and Wales.
Goosanders are medium sized members of the sawbill group of ducks, so-called because they have long narrow bills with saw like teeth, good for gripping fish. Their preferred diet is salmon and trout.
Upland river fisheries in particular, see goosanders as a problem. Not a surprise when you realise a young goosander needs 33 kg of fish to reach adulthood! Blogger Nick Hart witnessed them doing their stuff on the Deveron last Autumn:
Their synchronization was incredible, several birds corral the fish while others dive below the surface. Then they swap… …there were pods of these saw-bills guzzling fish amounting to in excess of 100 birds! The fish did not have a chance.’
These predatory ducks can be shot under license, and the government have now extended the control season to May at times of low flow, when salmon and sea trout smolt migrations are particularly vulnerable.
Image source: Hugh Miles
Otters are turning to ornamental fish
Hungry cormorants and goosanders are also causing problems for other river predators. Tim Paisley of the Predation Action Group, believes the increase in cormorant predation has created a chronic shortage of otters’ natural prey:
‘…otters, to an increasing extent, to seek their prey in what would not normally be their natural hunting grounds; still-waters, carp waters, fish farms, and even garden ponds… have all become part of the new hunting grounds
In the 1970s, otters were extinct across much of UK. That all changed in the 80s and 90s when Philip Wayre, founder of the Otter Trust, released 117 otters into an ecosystem that couldn’t support them. Ron Key of The Angling Times explains why this was a bad move:
‘Unfortunately the reintroduction of otters coincided with predation from other species such as the cormorant, signal crayfish and goosander, and the negative impact they were having on our waters. Predation is not just about otters. In recent years the otters’ main food, the eel has also reduced drastically, increasing the need for them to look at alternative food sources.’
It’s bad enough that otters now have extra competition for food. Add in the fact that they’re at the top of the food chain, and it’s no surprise that they’ve became a problem. Champion angler Bob Roberts comments:
‘The otter has no predators. It is the apex predator of the waterways. It did not exist everywhere in the past and certainly shouldn’t do today.’
It doesn’t help matters that otters fish for fun as well as food!. Shaun Harrison blogger for Angling lines describes them in action:
‘The problem with otters is that they work like cats and kill for fun as well as food… and then seem to delight in a couple of mouthfuls, and then leave the carp to a slow and agonising (I would guess) death.’
Anglers can’t do much to change the situation, as otters are a protected species, You’re breaking the law if you harm, them capture them, or destroy their breeding place.
As with otters, it could be argued that the problem with mink was also caused by human mistakes. American mink arrived in Britain in 1929. Suddenly in demand due to the popularity of commercial fur farms, they were reported to be breeding wild in the UK in 1956, due to escapees and deliberate release.
In 1998, animal activists released 8000 mink from a fur farm in North Staffordshire. A lot of the animals were trapped but the rest have populated vast areas of Staffordshire, Shropshire and Cheshire.
Smaller and slimmer than otters, with a deep brown coat, minks are more confident than otters and are spotted more often in daylight hours. They’re from the same family as stoats, badgers, weasels. According to the Canal and River Trust:
‘Mink are opportunistic predators who will happily eat a variety of fish, small mammals, birds and invertebrates.’
Like otters, they hunt for fun as well as sustenance, and often leave fish remains on the bank. They’re a particular threat to salmon and trout fisheries. As well as devouring fish, these creatures eat rare birds, and are having such a huge impact on water voles, that they may soon be extinct throughout much of Britain.
Volunteers with the Lochaber mink project are making a concerted effort to catch mink troublemakers. The process involves ascertaining exactly where the mink are coming to feed. To do this they use a mink raft.
‘Mink rafts have a tunnel over a clay pad; as mink go through the tunnel (they are naturally inquisitive) they leave tracks on the clay. Rafts can be checked every one to two weeks and so are less labour-intensive than trapping.’
Mink are then trapped on the rafts or by traps dug into the river bank.
Image source: shutterstock
Salmon-loving seals are being shot
Seal populations are extremely healthy around the UK coastline, and numbers have grown rapidly in recent years. While they enjoy salmon, these appealing creatures aren’t overly fussy about the fish they consume. Pike, bream and carp have all been victims. However, seals are fussy about which parts of a fish they’ll eat. They leave plenty of leftovers!
As seals are a protected species, non-lethal deterrents have to be the first port of call. Seal scarers that emit a high pitched noise can deter them. However, sometimes they become such a problem that fishery managers apply for a license to kill. They are regularly shot in Scotland under licence to protect salmon and sea trout stocks in estuaries. In 2013 alone, 200 seals were shot.
Even the RSPCA recognizes that the issue of seal control is far from simple. They say that there is significant evidence that fish can feel pain. They point out that farmers are also under legal obligation to protect their fish.
Seals hit the headlines in 2013, when a female dubbed Keith turned up in the River Severn following flooding. Convinced that Keith was depriving them of catches, anglers tried to bring in a hitman to get rid of the seal for good.
Blogger Carl over at Fishing Adventures wasn’t impressed:
‘Can you imagine what the anti anglers would say about that? It would be in all the papers, ‘Anglers shoot seal!’ Now that would do angling’s image a whole load of good… NOT! The other option is to find a humane way of removing it from the river, namely transporting it back to the sea.’
A tricky problem to solve, indeed. But the problems aren’t all about birds and mammals…
Image source: S. Giesen
Beware this destroyer of native shrimps!
D. villosis (aka the killer shrimp) is an aggressive predator which spread to the UK from Eastern Europe. This tiny terror kills and feeds on native freshwater shrimps, young fish and insect larvae.
Why do the shrimp’s feeding habits matter so much? According to Woodlands blogger Chris:
‘Where it invades, it tends to dominate the habitat often resulting in the local extinction of native freshwater species. This alien invader can be as small as 3 mm BUT can grow to be three centimeters in length – much larger than our native freshwater shrimps.’
Over the last few years, DEFRA has been running a campaign to raise public awareness of this killer. The key words of the campaign for all anglers are CHECK, CLEAN and DRY. All it takes to destroy any clingy shrimps is fifteen minutes submerged in hand-hot water! But if you don’t follow this advice, the shrimps can survive in your wet fishing gear for up to 15 days.
Worried that your other half isn’t going to be best pleased to find your fishing gear soaking in the bath? Angling coach Roger Patrick has come up with an inventive idea:
‘I bought a large plastic storage box and use that. It takes my boots, waders, landing net and reels… Easy really and it leads to greater harmony in the home.’
The Wildlife and Countryside Act 1981 prohibits releasing non-native species into the wild, but no one has been prosecuted under the law. However, some MPs are pressuring the government to allow environment officers to enter any land where they suspect invasive species are creating a problem.
Get back to basics
Anglers are agreed. When it comes to predators, we need to learn from our past mistakes. Blogger Hugh Miles, writes:
“There should be a law in place that allows Natural England to insist on an Environmental Impact Assessment before any release to protect the balance of nature. Releasing an apex predator into the wild should require a license.”
The Angling Trust believes that the situation will only change if the government focuses on restoring healthy fisheries. How this can happen?
‘Through controlling pollution, reducing abstraction and restoring habitats. This will make fish populations more resilient to otters, cormorants and other predators.’
So anglers, it’s time to take action! You can support the Angling Trust’s plan by doing one simple thing. Pay for a rod license (you probably do this already, right?). The Angling Trust currently uses rod license fees to employ three fisheries management advisors. These advisors coordinate the efforts of local fisheries to manage cormorant predation. They also help erect fencing to exclude otters, as well as placing submerged fish refuges in fisheries.
Have you had any close encounters of the predatory kind? Head over to our Facebook page and share your stories. We look forward to reading them!