May 11, 2022 | Blog, Events, fish

The Amazing Exe Salmon

Salmon mean a lot to people for their amazing journeys, their waterfall leaping skills, their size and their appearance in our iconic rivers. They have a place in the mythology of our culture as heroic creatures and sources of wisdom. And they are on the decline. Dramatically. They are at the centre of a complex eco-system and as such their decline makes them the proverbial canary in the mine. So what is going on? and inspired by questions gathered from the local community in the Exe Estuary boxes: Are the salmon coming back?

We are working with the Creative Arc (Exeter University), Exeter City Council and the Royal Albert Memorial Museum to run a project that explores the environment. As part of this we explored the RAMM archives and researched the tidal reach and the history of the river and the city and its tides over time. The mammoth Salmon caught in 1924 and weighing 27.8kg captured our imaginations and Salmon seine netting is now banned on the Exe as numbers are so low.   See previous post on The Last Salmon Boat. Salmon that do survive find their way back to the Exe estuary from far away near Iceland and then continue through the busy city of Exeter and onwards to the spawning grounds in Exmoor where they were born. We want to link the estuary as a transit place for many species with the wider river catchement to which it belongs and depends and the city to its more-than-human inhabitants and its relationship with the river as habitat, as source of food and life. This is the first of a number of blogs leading to our event in Autumn 2022.

We have set out to celebrate this creature and to highlights the challenges facing it. To do so we have begun by empathising with the creature and trying to see the world and the river and estuary as she sees it.

What is it like for the fish in the river as it passes though our man-made world? And how or what does she see? The former question has led us to propose a Salmon Run, a relay of runners taking on the length of the river from Sea to Spawning ground using the Exe Valley Way from Dawlish Warren to the River Barle, a tributary of the Exe on Exmoor. For the latter question we have explored the very lens they see through and the view from the waterline.

How the fish sees?
Fish eyes are popularly known to be 180 degrees. If a fish looks up it increases it’s view of what is above through refraction at the surface of the water. Strangely their eyes contain a perfect spherical clear lens inside a circular lens inside the actual eyeball. We have found that the inner sphere is so clear that it actually works as a ‘fisheye’ lens so naturally we have tried taking pictures through them to see as the fish sees! An ambition is to take a photo using a fish eye lens with the lens as the pin hole in a pinhole camera. Note: the lenses stay totally clear for about 1-2 hours after being extracted.

Yes these amazing perfectly round clear balls are from the inside of a real fish eye!

We would also like to revisit an experiment made by in 1906 American inventor Robert W Wood based on how a fish would see an ultrawide hemispherical view from beneath the water. Wood first coined the term fisheye was coined in 1906. This shows how a fish uses the natural refraction of light through the surface of the water. Below are illustrations showing the experiment, a result/print and a diagram of the fish using reflection as well as refraction!

 

How does it feel? The Salmon Run
Following the journey of returning salmon from the wild north Atlantic to the higher reaches of the River Barle, over one day in Autumn a relay of runners of different ages and abilities will pass between them a hand designed salmon icon from the sea to the spawning grounds – travelling right through the heart of the city of Exeter, a journey of over the 50 miles. During the time moving up river the salmon don’t eat and rely on stores of food energy accumulated at sea.  Each weir crossing slows their journey and depletes energy as they leap over concrete or traverse fish ladders, often pausing for long periods to wait for the water levels to be adequate for passage.

During the day the runners will encounter marker poles symbolising the salmon’s difficult passage including the river weirs and obstacles that they have to cross to get back up the river following their maritime journey finally arriving at their spawning grounds. The run will be a relay with the crafted fish as a baton.

The run will generate discussions along the way led by salmon specialists exploring the salmons skills and challenges encountered on the journey.

One of the challenges facing the salmon are the weirs of which there are at least 14 before they reach their spawning grounds. These are man-made dams. The first dams or weirs may have been to create pools to make it easier to catch the salmon and other fish. After that they were made to create water power creating leats that channelled water to water wheels. The growth of human intervention created barriers for the salmon which however they were able to adapt to famously throwing themselves up the weirs or waterfalls with gymnastic power. But the salmon’s ability to vault these huge structures depends on reliable amounts of water in the rivers at the right times and in the right qualtities.

The Exe Valley Way is made up of all sorts of surfaces including footpaths, tarred cyclepath and sections of road (some quiet, some not) and passes through the amazing quiet rural countryside and several beautiful villages with nice pubs!

Why is the salmon jumping over a log in our design at the top of this post? Well it is not. The thing that looks like a log cut through with tree rings (or indeed a finger print) is in fact the scale of a salmon which can be read to find out how much time it spent at sea and in the river and much more about the conditions in which it swam!

Recently books have been found containing records made by a Robert Gibson in Canada in which he intermittently smeared some scales from fish while recording individual salmon. These scales are turning out to be a goldmine of information telling us much about what has changed for the salmon in 100 years.

We continue our journey with the salmon, please get in touch if you would like to be part of the Salmon Run in Autumn as a steward or runner or if you would like to find out more or contribute to this project. Thanks to Phil Turnball at Westcountry Rivers Trust and Jamie Stevens at University of Exeter.

 

To find the Exe tides reach

To find the Exe tides reach

Finding Tides Reach Exeter (by canoe, paddle board and motor vessel) Where does the tide reach in Exeter on a high tide? How does this affect Exeter, its inhabitants and the creatures that live in and move through these waters now, in the past and what about the...

read more
Where Has Our Sand Gone?

Where Has Our Sand Gone?

Where has our sand gone?   The short answer is in the above illustration. But it is a bit more complicated! RED is Loss, BLUE is Gain. First a big thank you to The Plymouth Coastal Observatory who have provided these images and recorded this data. We have been in...

read more
Body of Water: water quality creative lab

Body of Water: water quality creative lab

Body of Water: a water quality workshop day Fish, amphibian, and reptile, warm-blooded bird and mammal-each of us carries in our veins a salty stream in which the elements sodium, potassium, and calcium are combined in almost the same proportions as in sea water.―...

read more
Wider Than The Sea

Wider Than The Sea

  What if the locals advised the visitors about their estuary? How to enjoy the place from an insiders view? And how to respect it in order to preserve it? ‘Wider than a river’ is a collection of generously shared thoughts and reflections from people who live...

read more
Pop Up: Starcross and Topsham

Pop Up: Starcross and Topsham

Pop Up Exhibition at Starcross and Topsham   We had a great two days sharing ideas, thoughts and artworks from the Exe Box and online activities in Starcross and Topsham over the weekend. Participation and interest exceeded our expectations and we enjoyed hearing...

read more
Galleries for Exe Box and online activities

Galleries for Exe Box and online activities

Tidelines Community Online GalleriesMaps, thoughts, diary entries and photos submitted as part of the ExeEstuary Box and online. Mapping the Exe Personal maps of the estuary Questions from the Exe Estuary Things we would like to know Exe Home Screen Phone framed...

read more
Lympstone to Exmouth Part 7 of Jon Seal’s 7 part film.

Lympstone to Exmouth Part 7 of Jon Seal’s 7 part film.

  Film 7 of 7: Lympstone to Exmouth https://youtu.be/eosDNNUuc2o Jon's 7th film completes the circle almost to it's starting point. For the final part of the journey, the stone makes its way from Lympstone to Orcombe Point. It passes through the estuary on to the wide...

read more
Illustration students and the estuary

Illustration students and the estuary

    Two groups of Illustration students from Pymouth University have been working with Tidelines on a project exploring how to draw greater attention to the diversity of life in the Exe estuary and the estuary as a living system. We had a series of online...

read more
High Water: Tides, Climate, Oceans and The Exe estuary

High Water: Tides, Climate, Oceans and The Exe estuary

HIGH WATER EVENT: 30 March 2021 Sarah Cameron Sunde Tidelines partnered with Art-earth and Low Carbon Devon to run the High Water event where 60 artists and scientists and others from all round the Uk and the world talked about their work and relation to the oceans,...

read more
Big Thanks You to boxers!

Big Thanks You to boxers!

Thank you so much to everyone around the estuary who has responded to the Exe estuary box challenge and returned boxes to us! We are so grateful for the time you have taken to share your maps, your questions, your thoughts and your creativity all about the estuary...

read more