An attractive new coffee-table book on our rivers and streams details the life of fish and how they can be protected, writes Marine Correspondent Lorna Siggins.
Everyone should have a river in their life, the late Douglas Gageby, former editor of this newspaper, once noted, and a new publication by freshwater biologist Dr Martin O'Grady makes a good one very possible.
He has incorporated 20 years of international experience into an illustrated training manual on restoring riverine habitats, which concludes that "nature is always best".
A senior research officer with the Central Fisheries Board (CFB), O'Grady has worked on rivers in Scotland, Iceland and Ireland, and many of the lessons learned at home have been applied to the new manual. Seeds for such a guide were sown after assessment of a successful €24 million programme, the Tourism Angling Measure (Tam), spearheaded by O'Grady.
Under the programme, initiated by former marine minister Dr Michael Woods and funded by the EU from 1994 to 1999, natural techniques were used to restore habitats on some 250 miles of rivers and streams across the State.
"After only a year or two, we could see a 10- to 15-fold increase in fish stocks in many cases," Dr O'Grady says. In some cases, improvement was by a factor of 30 - prompting US aquatic ecologist Donald A Duff, formerly of the US Forest Service, to describe Ireland as a "world leader" in this field.
The overriding principle identified by Dr O'Grady throughout was that if a river could regain its natural, physical form, it would recover - and so would its flora and fauna, including fish stocks.
As he notes in the text, since the last ice age the most significant changes to our river systems took place over the last century. Channels were straightened, riparian zones sometimes eliminated altogether and heavy farm stocking rates contributed to "bank trampling" and excessive erosion. He says arterial drainage was pretty disastrous, but "hindsight is a wonderful thing".
The economic imperative at the time favoured agricultural development. "Politically, the country is much greener now and marginal agricultural lands are less important for farming - with perhaps greater benefits to be accrued from tourism, including angling," he says.
O'Grady advocates a pragmatic approach which involves learning from mistakes without believing we can return to an historic landscape in which we were all hunter gatherers.
A healthy channel is one where there are stable banks preventing excessive erosion, enough shading to provide camouflage for fish and reduce high summer temperatures, decaying vegetation as a food source for certain macro-invertebrates, and "niche habitats" for invertebrates, nesting for birds and feeding for bats.
Land management practices which have had a negative impact all have one common feature, he says - they have reduced the physical complexity of channels, reducing ecological diversity and consequently fish stocks.
The manual gives an illustrated step-by-step guide to improving a habitat, using logs, rocks, conifer tree tops to stabilise banks, and willow slips for planting, and he includes a table on the advantages and disadvantages of different revetement approaches. There is a section on building weirs, and reconstructing pools in rivers - being a natural physical feature about every 25 to 35 metres of channel length.
Such pools provide temporary homes for all salmonids during severe drought, homes for bigger trout, and resting places for adult salmonids returning to small channels to spawn.
Coniferous afforestation is a significant problem, and one which O'Grady is still concerned about. "Coillte has made very big advances - it doesn't plant right up to banks, and is incorporating marginal bands of deciduous trees," he says.
• Channels and Challenges: the enhancement of salmonid rivers is available from Sandra Doyle at 01-8842600 or sandra.doyle@cfb.ie