Monday 27 February 2012

The 2006-8 daily salmon angling survey


 From 2006 - 2008 the Environment agency carried out a survey of salmon angling effort on the river Severn. The process produced a lot of useful information. This summary of the survey was sent out as a letter to Severn salmon anglers in April 2009. I've reproduced it below.

The new salmon season has now been underway for over two months and the general feeling on the ground is that it has been a slow start with less ‘spring’ fish and of a smaller size.  Lets hope it is the lack of rain that is slowing their progress rather than a lack of fish waiting to come into the river.  Despite the slow start a few nice fish have been taken from Diglis, Holt and the River Teme.  As last year this letter contains a summery of the results from the catch cards that you returned during the 2008 season and compared these results with those obtained from the 2006 and 2007 seasons.

For the second year running the 2008 season has certainly been a challenge, the fish were certainly there, particularly the ‘spring fish’ but the river was up and down like a yoyo making fishing either impossible, difficult and for a few brief moments ideal.  Despite the conditions, angling effort has remained good and the anglers have responded by altering their tactics and where you went fishing to maximize your chances.  Once again many of you have provided loads of information on the catch cards and I really appreciate this, it really helps us manage the fishery and hopefully this will provide a sustainable fishery for you and future generations.   I appreciate that some of the national salmon measures like the renewal of the spring byelaws and the loss of 15 minute river level information have not pleased many of you, but removing the support for the catch card scheme is penalizing the local staff who are really trying to improve the salmon stocks on your river. 

The split between methods showed that spinning was still the preferred method accounting for 46% of total effort, while bait fishing declined significantly to only 30% of total effort.  Interestingly fly fishing appears to have become more popular now accounting for 14% of total effort, up from 9% in 2007.  There are certainly some skilled fly anglers on the Severn, that have demonstrated that taking salmon on the fly is a real possibility throughout the river and this has been publicised through the various angling forums, time will show if this trend continues.

Flows

The graphs below clearly shows the different flow patterns between years.  2008, like 2007 can be classed as a wet year, making angling difficult, but allowing easy access for returning salmon, with many being reported in the Welsh headwaters in May.

                                    




How many fish were caught?

The 90 anglers who recorded angling effort, reported a catch of 129 salmon for the 2008 season a drop of 11% on 2007 (145 salmon).  We know the declared catch via the catch cards is below the actual total, but the detailed information provided for these 129 fish is very important to us.  At the time of writing the provisional statutory national catch return for the Severn is 293, which is up 12% on 2007 figure, suggesting that the decline recorded on the catch cards is most likely caused by lower participation in the scheme, if this decline continues I will have to review whether to continue with the catch cards.

By using our spawning compliance model, which takes into account catch and effort, it is predicted that the River Severn is meeting its spawning compliance figure, in laymen terms this means there are sufficient salmon returning to spawning to maintain a healthy fishery.

Who caught the salmon?

In 2008, 45 anglers or 50% (42% & 37% in 2006 % 2007) of all anglers who fished caught a salmon. 50% of all salmon caught on the river Severn were taken by just 11  anglers (11 & 9 in 2006 & 2007)

Where were the salmon caught?

2007 saw the fisheries high up the river benefit from the exceptional flows.  In 2008 flows were still higher than average but not as extreme leading to a better distribution of fish.  Diglis reclaimed it position as the most productive fishery accounting for 34% of all fish, having lost it to the Welsh headwaters in 2007, while the fisheries below all the navigation weirs contributed 52% of the total catch (75% in the dry 2006 season and only 36% in the extremely wet 2007 season).  All the fisheries up to the Welsh borders had a splattering of fish while the Welsh headwater contributed 18% of the total catch (40% in 2007 and only 2% in 2006)

What method was used to catch the salmon?

With the flows being less extreme in 2008, spinning was once again the most productive method accounting for 63% of all salmon caught (45% in 2007 and 69% in 2006.  Bait fishing success dropped to 29% of all captures, falling in line with that experienced in 2006 (25%) and showed that the exceptional flows in 2007 required a change of method and fishing location to land fish (51% of all captures fell to bait in 2007)

Fly caught salmon rebounded after the poor showing in 2007 thanks to the dedicated effort of a few anglers in the middle river, to a new high of 9% (4% in 2007 & 6% in 2006). 


Angling effort to catch a salmon?

The number of visits to catch a salmon varies throughout the river.  As in the previous years the most productive place to catch salmon is below the navigation weirs, the increased productivity shown in the Welsh borders in 2007 was  maintained with only a marginal increase in the numbers of angling trips to catch a salmon.  The River Teme and Shrewsbury showed a marked decrease but this is principally attributed to small sample size.  The lack of salmon and the effort taken to catch them at Atcham is cause for concern and further investigation is required to what is driving this trend, suggestions welcome.

The length of the average angling visit was more variable throughout the river.  Those fishing below weirs generally fish for the shortest period of time, but Diglis recorded another year on year increase in average visit length, suggesting anglers are increasing their effort here.  A general comment would be that there are fewer anglers out, but those out are spending slightly more time on the river. 


             

The cumulative total of fish taken during the season in 2008 fits nicely between the 2006 and 2007 season, with 50% of the total catch being taken at some point in June.  In a dry year (2006) the majority of the total catch is taken before May is out, while in a wet year (2007) fish capture was spread throughout the season. Unfortunately the grilse run was not thought to be that good which also slowed the rate of capture in the latter part of the season.

When do anglers fish?

As in previous years, angling effort is closely collated to river flows and to a lesser extent byelaw restrictions leading to subtle difference between years.  2008 was different to the two previous years as flows had allowed angling in all months including June and the perception that there was a good ‘spring’ run kept anglers on the bank.  August and September were dry with low flows and the perception that grilse were few and far between suppressing effort.  To just add misery to the season, when the rains finally arrived it wiped out the effort in October as the river rapidly became unfishable.


What size were the salmon caught?

The most common sized fish was 11/12lbs (29% of total), this was slightly larger than in 2007 and there were more larger fish (19lbs range) than in the previous two seasons, supporting the perception that the ‘spring’ run was not only improved but contained larger fish.  The largest salmon declared was 41lbs (not shown on graph below).  The average weight of all the fish caught being 11.4lbs, the highest during the study (10.25lbs & 9.6lbs in 2006 & 2007)


Catch and release?

The Severn achieved an overall catch and release rate from the cards of 71% in 2008, this increases appears to be the result of many of the fish being caught during the mandatory catch and release period.  The provisional statutory return put the Severn catch and release at just above 50%,  Catch and release on the River Severn is still low by national standards. 

Swollen Vent Syndrome

International research continues into this condition, but I am please to say under 2% of salmon caught on the Severn displayed symptoms, this reduction is mirrored throughout the Atlantic salmons range.


I hope you have found the information interesting and I wish you all the best for the rest of the 2009 season.

Yours sincerely


Charles Crundwell
Senior Technical Specialist (Fisheries)
April 2nd 2009



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