Re: Damage to migratory fish stocks by Fish-eating Birds

President Allan Cuthbert, 7 Norton Avenue, Prestatyn, Denbighshire, LL19 7NL Email:

Strategy Officer John Eardley c/o Vanner Farm & Caravan Site. Llanelltyd, Dolgellau, Gwynedd, LL40 2HE Email:

Conservation Officer; Chris White, 57 Normanby Drive, Connahs Quay’ Flintshire, CH5 4JX

Sir David Henshaw NRW Chairman

Via email:

18 May 2020

Dear Sir David,

I recently received an email from Ruth Jenkins accusing me of publicly criticising an NRW Board member. There were no details in the email as to when and where this had supposedly taken place. I attend the Welsh Fisheries Forum on behalf of CPWF and as such I represent anglers from across Wales, many of whom have expressed concerns about the actions (or rather in-action) of NRW and perceived conflict of interests of NRW Board members due to their membership of the RSPB when considering controls on avian predation of salmonids. In my response to Ruth I explained that I cannot be held responsible for any comments made at meetings by CPWF supporters when I was not present.

I am not aware of any public criticism either verbally or in writing that I have made.

In her email Ruth accused me of publicly criticising an NRW Board member and asked me to withdraw this or if I wished to raise this issue with you as Chair of the NRW Board. As I have yet to receive a response from Ruth to my reply perhaps it is now time to take this to the next level. My preference is to have an open and honest discussion about the issues around avian predation rather than to go public through a press release. The issue of avian predation has been talked about for more than 10 years but all we get from NRW and its predecessor is procrastination on this issue for fear of upsetting the RSPB and latterly Wild Justice.

One thing that seems to unite anglers is concern over the impact of increasing numbers of Goosanders and Cormorants on our rivers. At the last Welsh Fisheries Forum a paper was presented from the Fish Eating Birds Advisory Group (FEB’s) on behalf of Natural Resources Wales in which graphs taken from the Wetland Bird Survey (WeBS) conducted by the British Trust for Ornithology (BTO) “suggests” breeding pairs of goosander and cormorant are in

CPWF has the support of freshwater and sea anglers in Wales.

Visit our website at

decline whilst accepting that over wintering birds had steadily increased from the 1980’s. The implication from these graphs is that these FEB’s are not the cause of the decline in ‘fish stocks’ and particularly salmonids. To a lay person who supports the RSPB this is what they want to hear. The presentation was interesting in that there was more concern about a legal challenge from ‘Wild Justice’ than in the protection of fish stocks. Apparently there needs to be a detailed study (12 Months) almost certainly followed by a public consultation before any controls can be recommended let alone be put in place.

NRW are fond of claiming that they are ‘evidence lead’ so let us look at the evidence. In the first instance we need to look at the graphs taken from the Webs survey:

Note: We understand the 100 Index line in the graphs to be the average or mean of the years I995 – 2015. It would be more meaningful to the reader if the graph illustrated the actual population in order to present actual year population plots and trend.

You will see that the trend line in red for both species is showing a decline this gives the wrong message as it is referring to breeding pairs and not numbers of feeding birds over the winter period. The presentation made no reference to the fact that overwintering birds are on the increase. In the following I only consider the damage to fisheries from goosander over the winter period but the same applies to cormorants who are consuming the same or more salmonids.

The following graph is taken from the latest Wetland Bird Survey (WeBS) survey which uses data from the British Trust for Ornithology (BTO) Waterbirds in the UK 2018/19. Note the trend (blue line) in this graph is upwards this includes overwintering birds and is not restricted to breeding pairs. This graph may mirror the decline in migratory fish stocks from electro fishing surveys; the decline is at the moment attributed to climate change and pollution.

Note on graph scale:

This 1970 – 2015/16 Wales graph of goosander illustrates the rising longer trend of recorded goosander, from no population in pre 1970 to its present 2015/16 population expressed as the 100 Index.

“Contains Wetland Bird Survey (WeBS) data from Waterbirds in the UK 2018/19 © copyright and database right 2020.

So let us now consider the case against goosanders. According to the BTO an adult goosander needs to consume 400gm of fish per day and to raise a single chick from egg to adulthood requires 33kg of fish (goosanders typically have 10 chicks to feed) – these birds primarily eat fish to live. The graphs above do not declare numbers, they refer to an index. However it is clear in the graph for Wales that annual goosander numbers are increasing. According to the BTO the Status Summary for goosanders is as follows:

Status summary

Goosanders were first discovered to have colonised the UK in Perthshire in 1871, and spread from Scotland into northern England in the 1940s. Between the first two breeding atlases, the species expanded its range in northern England, and colonised Wales and southwest England. WBS samples became large enough for annual monitoring in 1980, and showed sustained population increase, apart from a slight dip in the late 1990s. The BTO’s two national surveys of sawbills demonstrated an average increase in population size of 3% per annum between 1987 and 1997. There has been considerable further range expansion since 1990. Reasons for the colonisation of the UK, and the subsequent range expansion and population increase, are unknown. The species’ winter trend in Britain, comprising British breeders and continental visitors, rose steeply from the late 1960s and peaked in the mid 1990s, before falling back, and now stands at early 1990s levels).

In order to determine the biomass consumed by goosanders and to keep the arithmetic simple consider 100 goosanders feeding over the winter period from November to March approximately 126 days. Assuming each goosander consumes on average 400gm of fish per day then over 126 days 100 goosanders can consume approximately 5 Tonne of fish during this period. Admittedly these birds may not feed every day but they tend to gorge feed so allowing for none feeding periods let us say these birds consume 3 Tonne of fish. On rivers which do not have coarse fish present they will only be eating salmonids (and maybe minnows, sticklebacks, loach and bullhead if present).

A typical smolt ready for migration is approx 100gm but during the winter period most fish eaten will be parr or fry with a likely average weight of 30gm which would indicate that the number of fish eaten is circa 100,000 over this period. We will refer to these as smolt equivalents. Over

the winter period goosanders can be found feeding on upland spawning streams i.e. feeding on smolt equivalents and once the food source is depleted in one stream they simply fly to the next. No doubt it will be claimed there is no evidence to demonstrate harm from goosanders to ‘fish stocks’. I use the term fish stocks as goosanders will also feed on rivers containing coarse fish (and on marine fish in estuaries) and by including these in the biomass consumed it is easy to show there is little damage to overall fish stocks. This is not the case on rivers which do not contain coarse fish.

The focus of NRW and other agencies in the UK has been on avian predation during smolt migration on the basis that a smolt lost on its migration to the sea cannot be replaced whereas a parr lost in a spawning stream can be replaced! The migrating smolt studies tend to indicate significant smolt losses on upper reaches of rivers but whether this is due to avian or other predation is not clear. The theory that we only need to consider losses to migrating smolts is that it is larger parr which smolt (they need to attain approx 100gm in weight) and these larger parr take up the best feeding stations. If these larger parr are eaten then their place will be taken by a smaller parr who will grow large enough to smolt once they have taken up the recently vacated feeding station and so there is no problem. I am not sure if this is a logical statement but it seems to be the one that ‘scientific opinion supports’ and therefore only investigation into predation during smolt migration is considered vital. However studying migrating smolts, important as this is, is an after the event study as recruitment of juveniles has already been decimated over the winter months.

The problem we face is the conflict between two protected species, on the one hand goosanders which are not endangered, not native (but who have naturalised in the UK) and which have no known predators in the UK and salmon and sea trout which are regarded as being ‘at risk’. In fear of reactions from the RSPB and Wild Justice birds are therefore treated as sacrosanct by UK agencies. Unless and until the biomass consumed by FEB’s is recognised as damaging there is little prospect of a recovery in our stocks of salmon and sea trout. Many angling clubs have counts of FEB’s on their rivers and from this it is possible to estimate the biomass loss to these birds but it seems we are not to be trusted to provide unbiased data for fear of a legal challenge from those who have no concern for our fisheries or the damage FEB’s are inflicting on migratory fish stocks. Both I and supporters of CPWF believe that the criticism of NRW is entirely justified and I would welcome the opportunity to discuss both this and other fisheries concerns with you in a face to face meeting.


Chris White

Conservation Officer: Campaign for the Protection of Welsh Fisheries (CPWF)

Leave a Reply

You can use these HTML tags

<a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>






A sample text widget

Etiam pulvinar consectetur dolor sed malesuada. Ut convallis euismod dolor nec pretium. Nunc ut tristique massa.

Nam sodales mi vitae dolor ullamcorper et vulputate enim accumsan. Morbi orci magna, tincidunt vitae molestie nec, molestie at mi. Nulla nulla lorem, suscipit in posuere in, interdum non magna.