10 June 2016

A window to the lost world of West African sawfishes

Between 1974 and 1975, Nigel Downing conducted what was probably the only in-depth research on live sawfishes in West Africa. A withdrawal in funding led to his project being abruptly terminated after only 18 months, and he switched to a laboratory-based research project in order to complete his PhD. Forty years later, I collaborated with him to resurrect some of the data he painstakingly collected in The Gambia and Senegal. Having myself spent much time in this region, searching for the now-elusive river monsters, his data brought to life a West Africa unknown to me – where rivers and coastal waters teemed with juvenile sawfishes. His stories have brought me closer to understanding what we have lost, both in West Africa and in other parts of the world.

Interview by Ruth Leeney. 

What were your research objectives in West Africa?
Dr. Jean Maetz, a French physiologist who ran a radio-isotope laboratory in the South of France, was keen to discover how elasmobranchs survived in fresh water. He proposed that I find suitable animals, catch them, look after them in captivity locally and then arrange the transport of about 20 by air to his laboratory. Then I would work with him using radioisotopes to study the flux of water and ions in and out of the fish under experimental conditions. This last part I never achieved.

Where did the idea for the project come from?
As an undergraduate student, in a lecture on osmotic and ionic physiology, I was informed that cartilagenous fish were stenohaline - unable to tolerate wide variations in salinity. While there are teleosts (bony fish) that can move from sea water to fresh water and vice versa, salmon being the best-known example, we were told that elasmobranchs were restricted to the sea. However, I knew otherwise. As a young boy in South Africa I was well aware of the Zambezi shark (bull shark), which had been held responsible for a spate of attacks off the Durban beaches in the 1960s. I even remember an ambulance arriving to pick up a shark attack victim off a beach where we used to swim. I also knew that this shark penetrated rivers and had frequently been observed in fresh water. Further, I had spent several months working at the Oceanographic Research Institute at the Durban Aquarium before going up to university, and knew that sawfish were also found in rivers as well as the sea.

Three things therefore compelled me to do this project: I really liked sharks; field work was my thing; and I was curious to find out how euryhaline elasmobranchs controlled their salt and water balance (osmoregulated) as they moved between salt and fresh water.

Were you aware that sawfishes were present in you study areas when you first started the project in The Gambia and Senegal?
My initial plan was to head back to South Africa, use the Durban Aquarium facilities and collect from the rivers and estuaries of Zululand, but that fell through. Dr. Maetz said he had heard there were sawfish in West Africa and so, as a result of hearsay, I ended up working between The Gambia and Senegal, both of which proved to be excellent places to capture bull sharks and sawfishes. By that point I had realised, from my time at the Durban Aquarium, that keeping bull sharks alive and healthy in captivity was going to be far more difficult than looking after sawfishes. The latter can happily spend hours on the bottom using their spiracles to ventilate, whilst bull sharks needed to keep swimming. For that reason, sawfishes became my primary study species. 

This adult male Largetooth Sawfish, 4.5 m in length, was landed by a fisherman in October 1975. (c) Nigel Downing.

Can you paint a picture of your fieldwork and day-to-day activities in The Gambia and Senegal?
I was based in Thiaroye, on the outskirts of Dakar (the Senegalese capital), at a French laboratory. However, I set out for the field very early on to establish where best to find the fish I needed. I discounted the Senegal River from the outset, and investigated most of the Gambia River in Senegal (by road) and in The Gambia (by road and by boat). Finally, I established two field bases in the Casamance, in southern Senegal. Sawfish appeared to be more numerous in the Casamance River and it was an easier place in which to work, and since I was based at a French research station, it made sense to do my fieldwork in Senegal too. 

Initially, my main priority was to find out where, when and how to catch small sawfishes. They can grow to several metres in length, and for obvious reasons I needed them neonatal-size, preferably. Once I had located them, the next phase was to keep them in captivity, locally. Thiaroye and the Casamance are miles apart, and there were no holding facilities at either place. So I had to build tanks and equip them with water circulation and filtration systems in Thiaroye, and pens along the river in which to hold recently-caught sawfish. Finally there was the issue of transporting them from the pens in the south of Senegal to the tanks up in the north. All of this took me six months, and I had only been given eight months in which to get the fish to France! I was given an extension to collect again in 1975, and with all the infrastructure and logistics firmly in place, I conducted an intensive sampling season in the Casamance River. 
Nigel placing a sawfish in a holding pen.

A typical day in the field went something like this: I got up well before dawn, left the empty classroom where I slept at a mission station and went to pick up the local fisherman, Timothé, who helped me with all my work in the Casamance. We would go back to the classroom, cook and wolf down huge bowls of porridge, washed down with cups of tea or hot chocolate. We then made our way to the river by car with all the equipment:  fuel, transport tank, net, syringes, portable centrifuge, battery, ice and much more. The boat was dragged into the water, engine attached, all the equipment was loaded in and we made our way to the river mouth. The net was set… and we waited. If anything was snagged in the net, we knew it and went to retrieve the animal immediately. If it was a sawfish, one of us held it firmly in the water while the other patiently disentangled the rostrum from the net. This could sometimes take up to 20 minutes to achieve. The animal was sexed, measured, and sometimes a blood sample taken. The animal was put into the transport tank and the water circulation system switched on. If another animal had been caught meanwhile, we would retrieve that one too. Then we had to dash to the holding pen to release the sawfish, before heading back to continue netting.
At the end of the day the net was retrieved and repaired by Timothé if necessary, while I took care of the boat and loaded up the equipment for the next day. I wrote my notes up by gas-light, cooked myself a meal and fell into bed, exhausted. The days were long and tiring.

By July of 1975 I had a holding pen in the river filled with 15 small sawfish. As I was preparing to transport them north, I was told that lightening had struck my tanks, and the research vessel that was to transport them had broken down. I released all the sawfish back in to the river, and headed back to my base in Thiaroye. Not yet defeated, I was able to arrange for the French Airforce to send a Nord Atlas transport aircraft to Ziguinchor (such things were possible in those days!), and in October 1975 I successfully transported six small sawfish by air to the tanks in Thiaroye, where they thrived. Despite this eventual success and the enormous effort I had invested, the project’s funding was withdrawn in December of the same year, and I returned to the UK, immensely sad and rather despondent. 

Adult female Largetooth Sawfish landed in The Gambia, 1975. (c) Nigel Downing.

You took a remarkable photograph of an adult female sawfish that was landed on a beach in the Gambia. Can you describe the experience of seeing that animal being landed?
I was very excited. Only a few days before I had helped collect an equally large female at Niani Maru, several hundred kilometres up the River Gambia and in fresh water. Now here was one taken in the sea not far from the river mouth, and she was pregnant with 15 young. It is such a shame that she had not delivered them, and I felt overwhelmed to witness all those baby sawfish so near to term, all out of the one huge female. I could only suppose that she too was about to make the journey upstream, and to deliver her young. Instead, in no time at all she was reduced to chunks of meat, ready to be dried, then to be bagged up and exported to Ghana.
The pups from a pregnant sawfish landed in The Gambia.

Forty years on, sawfishes are in danger of extinction throughout much of the world, and many may even have been extirpated from the areas where you saw so many of them. How does that make you feel?
I don’t wish to be too morbidly philosophical, but I believe very strongly that we are stewards of the world we live in and we are doing a pretty poor job of looking after it. The loss of the sawfish is global, with the exception of a couple of places where they are properly protected (Florida and Western Australia). I am sad that sawfish are probably no longer present in significant numbers West Africa. In other parts of the world, their recovery will depend on credible and guaranteed protection being put in place, which may be too much to ask for in some places.
The fishing net and motorised boats have been the demise of the sawfish in West Africa. Although they may now fetch a good price largely because of their fins, back in the 1970s the fishermen did not particularly like catching sawfish. They were not valued as fresh food, and they made a huge mess of their nets.

What influence did your time in West Africa, working on sawfishes, have on the rest of your life, your interests or attitudes?
Overwhelmingly I feel a sense of privilege. I have to pinch myself sometimes to realise what I experienced and witnessed some 40 years ago. The experience of working largely alone and undertaking the task I did certainly formed me, and I would never trade it for anything, tough though it was at times.

Nigel’s description of the time he spent studying sawfishes in West Africa provides a solemn and somewhat dramatic contrast to the present day and highlights the almost complete loss of these extraordinary creatures from the coasts and rivers of Senegal, the Gambia and many other West African countries over just a few decades. I hope, however, that his story will inspire others, as it has me, to seek out and protect any remaining sawfish populations in far-flung corners of the world, lest they too meet the same fate.

This article was first published in the June 2016 edition of the Save Our Seas Foundation magazine: http://www.saveourseasmagazine.com/west-african-sawfishes-window-lost-world/

A blog post on how the sawfish specimens Nigel brought back to the UK are being used for contemporary sawfish research and conservation: http://saveourseas.com/update/the-ghosts-of-sawfish-past/ 

03 April 2016

The Ghosts of Sawfish Past

I never thought that a few days working in a museum would inspire me. The quiet, ordered presentation of the natural world in a setting locked away from the elements has always lacked what I love most about research and wildlife: being outside, in wild places; the excitement of searching for and eventually seeing live animals; observing and documenting those experiences. Fieldwork is, for me, the most meaningful part of biological research because it is a process of discovery – of the natural behaviour of animals, of the ways in which the fate of animals, habitats and human communities are linked, and of my own strengths and limitations.

A handful of rostra (saws) from young Largetooth Sawfish collected from the Gambia River in 1974. (c) Ruth H. Leeney.
But sitting in the basement of the University Museum of Zoology, Cambridge, I became immersed in a different type of discovery. It was like opening a long-lost, dusty volume filled with stories of expeditions through West Africa. Not from hundreds of years ago, but nonetheless a different era in terms of sawfish populations – the 1970s. What a difference forty years can make

Nigel Downing putting a sawfish into a holding tank, 1975. (c) N. Downing.
In 1974 and 1975, Dr. Nigel Downing conducted a study of sawfishes in the Casamance and Gambia Rivers, in Senegal and The Gambia respectively. He worked in collaboration with local fishermen, asking them to bring him any sawfishes they caught. Back then, sawfishes were no more than a nuisance to local fishers – they entangled and damaged their fishing nets, and had little value at market. They caught a great many, especially during the rainy season when there was clearly an abundance of pups (juvenile sawfish) in both rivers. The fishers usually kept only the rostra (saws), sending the meat to Ghana where dried shark and ray meat was, and still is, popular (international trade in sawfish parts has only been prohibited since 2013). When Nigel’s project was brought to an abrupt close, he was able to bring over 40 sawfish rostra back to Cambridge, where they have since lain unnoticed. Until now. 

Before me were four wooden drawers holding carefully-wrapped layers of tissue paper, which I folded back to reveal bundles of rostra from very young sawfishes.  I have never seen so many sawfish rostra all together in one place. On some, the skin still had a golden iridescence, while others were still encrusted with river mud or bore a solitary glittering fish scale, impaled on a needle-sharp tooth; they seemed like a collection of careworn Christmas decorations. In these museum drawers lie the relics of a time when sawfish saws could be collected by the handful and were worn on the headdresses of the Bijago people of Guinea-Bissau, or placed on the roofs of houses in The Gambia and Senegal to protect families from evil spirits. One of nature's most decadently-decorated animals, and the traditions it inspired, now only a fading memory in most West African societies

In the stillness of the museum’s basement, where all is clean, carefully stored and climate-controlled, I felt a million miles from the dust, mud, burning sun, clamour and stench of fish markets and the general sensory overload that comes hand-in-hand with my usual fieldwork in Africa. But as I eyed the museum treasures, I was transported back in time to a different West Africa: one where rivers teemed with baby sawfish. Fishermen in Guinea-Bissau had described to me how, years ago, they went to the beach at night and speared small sawfish in the shallows by the light of their torch flames. Holding the miniature saws of young sawfish in my hands, I imagined and wondered at such a scene of abundance – a scene that exists no more. 
Juvenile Largetooth Sawfish caught in The Gambia in the 1970s. (c) Nigel Downing.
Nonetheless, these ‘Ghosts of Sawfish Past’ can reveal stories never before documented. Although sawfishes disappeared from much of the West African coast several decades ago (we’re still not sure where, if anywhere, in West Africa they remain), museum collections can tell us much. Which species lived in the Gambia River and which in the Casamance River? Were they closely related to the sawfish found on the other side of the Atlantic, in Florida and the Bahamas, or were they different? Did sawfishes from these two rivers move large distances along the West African coastline, or did they stay close to the areas where they were born? Genetic analysis of the dried cartilage from sawfish saws is now possible, and will answer some of these questions. It may also help researchers to understand whether sawfish populations might be able to recover in West Africa or if, once gone, they are gone forever. I’ll soon be heading back to the mangroves and coasts to continue my search for Africa’s last sawfishes, but with a new respect for the invaluable role museums can play in providing a window to the past. Knowing what has been lost in West Africa, can we redouble our efforts to protect the sawfish populations that remain, before they meet a similar fate? 

Many thanks to Matt Lowe, Collections Manager at UMZC for facilitating access to the collection and to Save Our Seas Foundation for funding my visit to the museum. 
This blog post was originally published on the Save Our Seas Foundation website: http://saveourseas.com/update/the-ghosts-of-sawfish-past/