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Cormorant and Goosander Watch
Angling’s representative body in England, the Angling Trust, has launched a new web site for anglers to record sightings of cormorants, goosanders and mergansers throughout the UK
The new site is easy to use and will gather vital
data to help persuade government of the need for action to protect fisheries.
It has been launched to coincide with the start of the coarse fishing season on
rivers.
The Angling Trust succeeded in persuading the Fisheries Minister Richard Benyon
to carry out a review of the licensing procedures and he has stated that he is
prepared to take “bold decisions”. As part of this review, the Trust needs data
on the abundance of cormorants to convince the government to take decisive
action.
Anglers can record sightings and activity of
cormorants anywhere in the UK, directly onto a Google Maps driven micro-site
at
www.cormorantwatch.org Users will also be able to scroll around the map and
zoom in to view details of each recorded cormorant sighting and watch the real
picture of cormorant predation in UK waters build up week by week.
The Trust’s aim is to persuade DEFRA to simplify licensing procedures and allow
greater controls on cormorant numbers. It is hoped that this data will also be
factored into a wider pan European study on cormorants.
Angling Trust Chief executive Mark Lloyd
commented “This is a moment when
anglers need to stand up and be counted. If people don’t record sightings
of cormorants and other fish eating birds on this site, then the politicians and
civil servants will not have the information they need to make decisions which
could affect the future of fishing for the next generation. It takes less than
a minute to record a sighting. All anglers who see one of these birds in the
next few months must make the effort to visit
cormorantwatch.org and put a pin in the
map, whether they are a member of the Angling Trust or not.”
In other words - take on the Bunny Huggers - whose rose tinted views seem especially to hold sway in the Principality.
And this initiative is particularly important on the Towy
Goosanders are now well established on the Towy main river and have also been observed rifling through gravels following fish spawning in tributaries. It has been estimated that each goosander family will consist of 1 male which may be absent half the year, 1 female, 6.5 ducklings - which will fly late in August and disperse, possibly gradually leaving the fishery by the end of December. In addition, there will be 2 or more miscellaneous birds feeding on the fishery some if not all the time.
The total annual intake in kg of the goosander family group is likely to be :—
Male 98.91
Female 143.08
Young 248.255
Misc. 161.252
Total 651.507 kg of fish
From this must be deducted the lost intake during muddy water conditions - about a quarter in the case of the Towy, but this is a high rainfall catchment and recent observations indicate that the birds simply move into clear flowing tribs or nearby catchments. The percentage of salmonid intake will depend upon availability. Although goosanders much prefer salmonids, they will continue to prey on other species in their absence.
Roberts G 1988 “An assessment of the impact of large avian piscivores on salmonids in the Towy river system”. CFF May 1988.
OTTERS
It's a pity there is no column in the reporting procedure to include those cuddly little otters - now widely spread locally - who can also have a significant impact on fish stocks.
Kruuk (2006), working mainly in Scotland, during his own studies and desk research found that otters require a food intake of some 15% of their bodyweight daily; will feed mainly on fish and lamprey, but also on eels (now declined locally by 95%) and miscellaneous prey. A female and two cubs will take some 3 kg/day. A male otter might kill a spawning adult salmon daily, usually male, consuming just 1 kg. At one spawning ground, otters were estimated to kill 23% of the fish present, 81% being males.
It was found on the Dee (Scots) tributary, the Beltie Burn, length 32 km, average width 4 m, surface area 7.9 ha – similar to some Towy tributaries – the annual fish production, mainly salmonid was 16.6 g/m2 with a standing crop of 14.4 g/m2. A pair of observed otters were calculated to have consumed 8.6 – 10.8 g of salmonid per m2 per year, accounting for 54 -68% of the annual production or 60 -118% of the mean standing crop.
An interesting aspect of Kruuk’s work is of direct relevance to the upper Towy where unnaturally cold bottom water is discharged from Brianne. Otters require 0.8 – 1.8kg (representing 3600 – 8100kj) of fish per day for the calorific contents of the prey to match energy expenditure. Any otter trying to exist on the upper Towy would have to rely on prey other than fish (frogs, rabbits) where fish stocks are unlikely to be sufficient to provide the food intake required to match the additional energy expenditure in the cold water.
Kruuk H 2008 “Otters – ecology, behaviour and conservation”.
Oxford University Press 2008.
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