River Clyde Forum Cormorant Census
Cormorant census carried out by forum members
River Clyde Cormorant Survey/Census:26/02/2011
Count Results on -
Tulliford (water meeting of the Douglas water and the Clyde) (22 birds)
Glasgow Green (21 birds)
Bothwell road site (12 birds)
Strathclyde Country Park (pontoons on the loch) (22 birds)
Total of 77 birds confirmed
The count of birds at Bothwell road was far lower than the last count, thankfully
Frank (Goldfinch) volunteered to check out Strathclyde park where 22 birds were counted.
We
can only guess that the birds previously counted at Bothwell road had moved to the
pontoons on the loch today for some reason.
This cannot be confirmed as Strathclyde
park was not checked at the last count.
Assuming the birds over winter from mid 15th September to 31st March the above figure of 171 lbs multiplied by the number of days 197 = 98.5cwt.or 4 tons 18.5 cwt. Almost 5 tons of fish consumed over the 6 month period.
While some birds return to the coast in April, there is a resident group of birds stay inland, further censuses will be undertaken during the summer months to establish how many stay.
In Monetary Terms
It is difficult to work out what price you put on each species of fish that they consume, however basing the figure on the price of brown trout.
Daily Intake: 171 lbs x £10.25 = £1,752.75
The question is can the river sustain this level of predation without it effecting
the whole eco-
Difficult question to answer as no real impact assessments have been undertaken on a river system or is there the methodology to undertake such a survey as far as we can ascertain.
This is where anglers can play an important role by keeping a record of all the fish they catch no matter the species or size, highlight any drop in annual catch rates or lack of particular species, log where and when they witness cormorants feeding,
take photographs of damaged fish, only by collecting trends and facts over a period of time can our case be made.
Total numbers from the three sites
114 birds (05/02/2011)
Adult Cormorants weigh approximately 4+lbs and are known to consume 30% of their body weight each day. This equates to 1lb.8oz of fish per bird, per day however, birds have been known to take fish 2lb plus in weight so the above figure is an average daily intake.Using the above figure of 1lb 8oz per day for each bird x 114 birds = 171 lbs daily.
View River Clyde Cormorant Census in a larger map
Cormorant roost’s on the river
