Salmon populations are at a low point of a long slow decline, the origin of which dates back before the 1960s.
Independent angler Trevor Worth recalls the time when his primary school class was marched down to Tavistock Town weir to witness a prolific run of salmon coming up over the weir.
"It was a fantastic sight, wherever you looked there were great fish leaping out of the water in mid-air, some hitting the weir and bouncing back but always more and more. Sadly those days are gone."
Dr Dylan Bright, Director of the Westcountry Rivers Trust (WRT), says the reasons for the decline in Atlantic salmon are many and varied but he highlighted man's impact on the river environment.
"Post-war agriculture has greatly intensified land use and this has implications for water quality and salmon survival, particularly at the juvenile stages and as eggs.
"The human population has risen hugely over this period which has increased our use of water and discharges. Also we have put up weirs on our rivers for hydropower which, far from being green energy, destroy rivers and their migratory fish populations."
Dr Bright noted that the most obvious manifestation of climate change is the pattern of rainfall with years of droughts and summer floods.
"We've also seen increasing temperatures in our rivers in summer which are not now far below those which are fatal to our Atlantic salmon – the recent droughts and floods exacerbate all the other problems of flow, temperature and pollution and push this iconic species ever closer to a critical point."
Research by The Game & Wildlife Conservation Trust (GWCT) highlights Atlantic salmon populations on the river Frome have shown a 40-year decline and the charity believes the situation is replicated on other rivers across the region.
Although they have seen some short-term improvements in salmon numbers in recent years, Dr Anton Ibbotson, from the GWCT's Salmon and Trout Research Centre on the river Frome, said that the size of the 2012 smolt run was estimated at fewer than 7,000 fish in comparison to runs that have reached around 13,000.
"This will undoubtedly have a major consequence for adult salmon returning to the river Frome and other rivers, in the next few years.
"The impact of drought in 2011 resulted in a depleted population of juvenile salmon most likely because of a reduction in habitat.
"This has now been compounded by the extreme flooding we've seen since last spring. This will have 'knock-on' effects for the smolt output in 2013 and returns of adult salmon through to 2015."
Ivor Llewelyn, of the Atlantic Salmon Trust, said: "A key problem has been survival at sea and the consequent number of salmon coming back from their oceanic feeding grounds. We don't know but guess it is something to do with changing sea conditions. We've also got all sorts of pressures in the rivers which have been going on for years – such as pollution, barriers to migration and the latest development hydro power which is causing us concern. However we believe the fundamental problem is at sea; we need to do what we can to address this, and also to make sure that salmon fry and parr thrive in our rivers, are able to leave them in good condition and can reach their spawning grounds when they return."
Mr Llewelyn added: "Because of climate change we are concerned that salmon are going to find life increasingly difficult. Less water and higher temperatures could see a fundamental long-term change in our rivers. This emphasises the importance of improving conditions for salmon in them, with better shade and sequences of fast water and deep pools."
Charles Huntington-Whiteley, partner with Strutt & Parker in Exeter who acts as an agent advising on all aspects of fishing, commented that the decline of recent decades has been dramatic.
"The spring fishing runs, that always saw the biggest fish, have all but disappeared in Westcountry rivers and all the runs are much smaller."
He added: "Like all environmental issues this is an incredibly complex problem and the difficulties include the vast number of vested interests, sometimes conflicting. The conservationists encourage the returning of caught fish and most rivers have restrictions to enforce this, but if a hooked fish has been played for 20 minutes then had the hook removed from the back of its throat, what condition does it swim away and what is its chance of survival? – I'm really not sure. The fishing rights are extremely expensive assets and owners are unlikely to be happy with any suggestion of limiting their enjoyment of those rights. If we stopped angling for salmon in the Tamar would there be a difference in the long term? Yes probably, but to what degree, it is a hugely complex problem.
"The real challenge is how the overall catchments are sorted out – it needs buy-in from everyone from government agencies, landowners to anglers."
Trevor Worth, who mainly fishes the Tavy, said: "I hooked my first salmon at the age of eight. I am very passionate about fishing and I've ended up a bit of an amateur naturalist, which is part of the sport."
He added: "There has been a serious decline in the number of salmon running the river Tavy but I'm upbeat and positive as there are a lot of people working together to improve the situation.
"As a layman angler the only thing that I can do to help is not to be greedy. One side of the fishing fraternity can see well ahead for the future of salmon but the other side – what we call fishmongers – have no interest apart from taking their trophy home.
"Times have changed. The end of the season (October) used to be the best time for fishing but now it's an anti-climax as the run comes earlier. Similarly catching a salmon in the spring is non-existent now – the earliest I've seen salmon is April but usually it is not until June or July depending on the water levels. In the current climate I feel it's pointless catching the salmon because it is putting us out of our own sport."