All complete!

Thanks to funding from the Heritage Lottery Fund, Associated British Ports, Green Ports Hull, The Environment Agency, Yorkshire Water, The Wild Trout Trust and Biffa Award, DCRT have successfully completed the fish passage solutions on the five weirs in our Living Heritage of the River Don project.

It all began at Steelbank in July of 2016 and was finished at Brightside in December 2016.

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This work complements a programme of fish passage work undertaken by others on the Don

There are 21 weirs on the Don between Doncaster and Beeley Wood Lower weir above Sheffield City centre.  At the time of our bid to HLF ten were already passable to salmon.  In December of 2015 salmon were seen and recorded jumping at Aldwarke weir on the Don.  This was the season after a hydroelectric scheme with a fish pass had been installed at Thrybergh weir, the next weir downstream.

Since then our project has addressed five of the ten remaining weirs; those that are considered ‘orphaned’ weirs. The project has reconnected 6.5km of the Don and opening up 10km of spawning grounds to migratory fish in the middle of Sheffield. Of the remaining 6, Aldwarke weir had a fish pass installed as part of a hydroelectric scheme in 2016; the Environment Agency demolished Beeley Woods weir and work commences on Ickles weir in May of 2017 as part of a biomass power plant.  There are plans for the remaining three weirs Jordan Dam (Yorkshire Water); Sanderson’s weir (Sheffield City Council) and Masbrough weir (Canal & River Trust).

Salmon to Sheffield by 2020?

 

 

Eels and the Don

Of all the species that frequented the River Don in medieval times, eels were by far the most sought after and most valued.  Salmon in comparison were regarded as fare only for the poorest in society, but eels were what graced the tables of the gentry.  Many of the most productive eel fisheries, for instance those in the fen areas in the tidal part of the river, were the preserve of monastic orders and those that exploited the fish stocks paid heavily for the privilege.

There is little doubt that the Don was an exceptional eel fishery. In his diaries written between 1701 and 1704 Abraham de la Pryme,the Vicar of Thorne, wrote the following words, referring to the lower part of the River Went which joins the Don close to Rawcliffe.

‘‘The river is no more than six yards wide but the crookedest and deepest that I have seen in my life. Every turn makes a great bog on the other side on which the water is thrown by the current and there is delicate fish therein. But such quantities of eels like was never seen. Sometimes there will break out or fall out from the hollow bank sides when the people are a fishing such knots of eels almost as big as a horse, that they break their nets’’.

He goes on to describe the annual elver runs which occurred at that time.

 ‘’Commonly every May such vast numbers of young eels comes over the water wheels with the waters and runs into the mills, that they are forced to give over working and send into town for the swine to devour them for they are as innumerable as sand grains on the seashore’’.

For those who are familiar with the lower Went de la Pryme’s description of the river could hardly be further from the truth. Land drainage works, carried out over the last couple of centuries, have reduced the river to little more than a featureless canal and whilst eels can be caught here, the numbers that he describes are almost beyond our imagination.

It is difficult to ascertain for how long after de la Pryme’s description was written that eel populations remained so abundant, but what we do know is that by the beginning of the 20^th century, eels had  been all but eliminated from the River Don and its major tributaries.

The gross pollution created by the emergence of the Don Valley as one of the largest and most important industrial sites in Europe, created conditions which were untenable to fish life and reduced the river system to little more than an open sewer for more than a century. To compound the situation for eels, weirs, sluices and pumping stations were built all along the river in an attempt to control flooding and to provide conditions suitable for navigation.  These structures created a barrier to migration and as the efforts to control and reduce pollution began to take effect in the 1990’s, they prevented any natural recolonization from occurring.

Elements of the life cycle of eels still remain a mystery to us but what we do know is that the juvenile eels (elvers) appear around our shores in early spring and begin to move up rivers to find conditions suitable for their further development.  They can remain in our rivers for up to twenty years and occasionally longer, but then begin their return migration to what is believed to be the Sargasso Sea of the coast of North America to reproduce.  This unique life cycle presents problems when it comes to trying to rebuild eel populations.  Whilst opening up opportunities for elvers to bypass obstructions is essential for the future of the populations, such action has to be recognised as a long term strategy.

One of the first issues tackled by DCRT following its formation in 2006 was to look at how we could perhaps speed up this process.  The small numbers of elvers which would be entering the river initially would take 15 to 20 years to mature and it would be at least a further year before their progeny returned back to the rivers of the UK.  What is still unclear is whether these juveniles return to the river from which their parents emerged in the same way as salmon do but it was clear that any support for this process would be beneficial.

A further problem was that the runs of elvers entering Europe’s rivers had shown a marked decline to the extent that it was estimated the populations were down to only 10% of the historic levels. New legislation had to be introduced to control exploitation and one of the actions required a proportion of the commercial elver fishery catch to be made available for selective restocking of suitable waters. The Trust saw an opportunity to become involved in this process and selected a number of sites on the River Dearne including Old Moor Bird Sanctuary and Bolton Ings Nature Reserve.  These sites provided the conditions conducive to eel development, being quite shallow and productive with ample reed and weed cover.  In order to ensure the eels had freedom of movement,  when required, sluices which controlled water levels into and out of the sites were also adapted.

In total more than 100,000 elvers were introduced into sites on the Dearne and Don and subsequent capture of stocked eels has shown rapid growth rates. The population of eels in the River Dearne itself has also shown a marked improvement indicating that the adapted sluices are working as required.

Restocking of young eels presented an opportunity for the Trust to involve the public in its work and to re-engage people with their local rivers. During 2014/15 more than 20 schools were offered the chance to have tanks of elvers in their classrooms and to care for them and feed them for up to 2 months. The children were then invited to release them into local waters. A further 60,000 young fish were released this way. The enthusiasm shown by the children who participated was wonderful to witness and almost all of them took the opportunity to physically handle the fish as they were released into the waters. This experience will no doubt live with the children for the rest of their lives and help to engender a better appreciation of the value of their local river environments.

The huge changes that have taken place to the physical structure of the River Don and its tributaries mean that we will never again witness the amazing sights described by de la Pryme but we like to think that our actions have helped to secure a future in our local rivers for these fascinating creatures.

 

Chris Firth MBE

Hidden Beauty

When you look upon a riverbed it can seem pretty drab, lifeless and uninteresting. But if you could take a pebble in your hand and somehow magnify its surface so that the microbes that covered it were visible, you may well be surprised by the beauty of what you saw. For throughout the slimy layer of life that covers the pebble you will find diatoms, a very pretty type of algae.

A boring brown riverbed? Photo by Matt Smith / CC BY

Like most plants and algae diatoms photosynthesise, deriving their energy from sunlight. They differ however in that they have yellow-brown rather than green chloroplasts, which contributes to the general brownish colour of riverbeds. The slimy layer in which most river diatoms make their home is known as a biofilm. This film coats most surfaces in rivers and lakes, and is comprised not only of diatoms but also a myriad of other microorganisms such as bacteria, protists, fungi and worms. Numerous invertebrate species such as certain mayfly larvae and freshwater snails graze upon biofilms, and are in turn prey for predators such as brown trout or dippers.

Diatoms are not restricted to freshwater ecosystems, and are in fact very widespread. Vast quantities float as plankton in the ocean. However they don’t necessarily need much water, and will live wherever there are moist soils or damp surfaces. There are an estimated 100,000 species worldwide.

Two plates of diatoms from Ernsrt Haeckel’s Kunstformen der Natur (Art Forms of Nature; 1904)

While diatoms are very abundant, they have an uncommon beauty. They come in a wide variety of symmetrical forms and have ornate and patterned cell walls. This is why they became a popular subject of study for those who pioneered the use of early microscopes. Their striking appearance led to their inclusion in Ernst Haeckel’s Kunstformen der Natur (Art Forms of Nature; 1904), a book that displays a collection of the famous biologist’s most beautiful drawings and watercolours.

One of Dr Dave Chandler’s diatoms taken from his laboratory experiments (false colour image).

There is also a more mundane reason to study diatoms. Their communities change in response to human impacts such as pollution, as some species are more able to withstand contaminated waters than others. Environmentalists can therefore collect diatoms from a river and compare what species they have found to what should be growing if there wasn’t any pollution. The difference in the diatom community then gives us a good clue as to how polluted the river is. Dr Dave Chandler investigated the impact detergents had on diatom communities during his PhD at the University of Sheffield. During his research he took pictures of the diatoms he kept in his experiments, not because he needed to for his studies, but simply because they made such beautiful subjects.

Another of Dr Dave Chandler’s diatoms (false colour image).

 

12 months on

Our Living Heritage of the River Don project has now been up and running for 12 months and what a year it’s been!

We have three fantastic members of staff who, along with our first apprentice have been busy out and about motivating people and doing a great job of clearing litter from the riverbanks, re-building stiles and fences and generally making the river a more welcoming place to visit.  All of our volunteer opportunities are available on our events calendar on our website.

We also connected with young offenders who through a series of workshops painted a stunning mural on a heavily graffitied bridge in Doncaster.   Look out for others over the next couple of years.

 

Our team have also been getting local youngsters interested in their local rivers with our River Guardians project.  The kids have been looking at bugs and beasties found in the river as well as the surrounding habitat and we have lots of activities to help them learn and inspire their interest.  At local fairs we have been having fun with our giant salmon and weirs game and badge making is always a sure way to interest the kids as we’re talking to the adults!

Our programme of works to install fish passage over 5 weirs in the River Don is now complete and complements a programme of fish passage work undertaken by others on the Don like Canal & River Trust and the Environment Agency.  The works began at the end of July and were completed at the end of December, thanks to good weather conditions.

We have also been working hard on the Don Valley Way, a new walking trail that follows the River Don from Doncaster to Sheffield. It’s 29 miles long and has a series of smaller, circular heritage walks leading off the main trail for those not interested in walking the whole 29 miles!  We will be launching the trail and its dedicated website along with the accompanying audiotrails later in 2017.

To entice you further to visit the river Josh, our apprentice has been laying geocaches designed to help our wonderful salmon trackables to navigate the river and back to the sea.

Geocaching is a treasure hunt that enables anyone with a smartphone to take part (more about Geocaching here)

We’re looking forward to another inspiring year with our fantastic team, there’s a lot going on – check out our calendar for events and activities near you and we look forward to seeing you when we’re out and about!