The Search for Sawfishes in West Africa

Sawfish researcher Ruth H. Leeney writes of specimens in the Museum of Zoology, and the plight of these amazing animals around West Africa today:

Of all the shark and ray families, sawfishes are considered to be the most endangered. Sawfishes are large, shark-like rays which inhabit the shallow, coastal waters of tropical and sub-tropical regions. Once common in these regions, sawfish populations have declined in recent decades and sawfishes are now thought to be extinct from many parts of their former range. Coastal fisheries, especially trawling, and entanglement in fishing nets have been central to the demise of sawfishes worldwide. In some areas, sawfishes have also been targeted by the shark finning industry, and the loss or degradation of mangrove and estuarine environments, which are important habitats for juvenile sawfishes, may also have had an impact on populations.

Two species of sawfishes, Pristis pristis and P. pectinata, formerly inhabited the east Atlantic, including much of the West African coast. Sawfishes were probably once a common sight in West Africa. Cambridge biologist Budgett (1899), on an expedition to The Gambia colony, wrote ‘…frequently in the morning, when the trammel-net was examined, a Crocodile (Crocodilus cataphractus) or a Sawfish (Pristis perotteti) had to be slain’. Likewise, a Swedish study (Svensson, 1933) carried out in the 1930s suggested that sawfishes were plentiful in Gambian waters: ‘This sawfish is common in the river at all seasons. . . . [I]t was [also] caught in remarkably great numbers, just at the mouths of creeks.  It is known by the natives in all parts of the river in the Gambia’. Forty years later, Nigel Downing, then a PhD student at Cambridge University, encountered many largetooth sawfish in the Gambia River. Fishermen working several hundred kilometres upriver in freshwater often caught sawfish, particularly juveniles. At the coast, Nigel also encountered fishermen hauling a 5-metre female largetooth sawfish, pregnant with 15 pups, onto the beach. Between 1974 and 1975, Nigel collected numerous rostra and some complete sawfish specimens, which he brought back to the Museum of Zoology in Cambridge. These specimens will provide an enormously valuable contribution to an ongoing study examining the differences in rostrum structure amongst sawfish species and even amongst regional populations of the same species.

Interviews conducted with fishermen in The Gambia earlier this year suggest that sawfishes are no longer a common sight and may in fact be locally extinct. Up-to-date information on sawfish abundance and distribution in African waters is almost completely lacking. This, of course, hampers any attempt to protect any remaining sawfish populations, since we do not know where to focus efforts or what the local threats are. The Protect Africa’s Sawfishes project is attempting to collect baseline data on sawfishes throughout Africa, to assess where sawfish populations still persist and where best we can focus conservation efforts to ensure that these unique and fascinating fishes do not disappear completely from African waters.

For more information, visit the project’s facebook page: https://www.facebook.com/ProtectAfricasSawfishes

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Leafy Seadragon, Phycodurus eques

Roz Wade, Interpretation and Learning Officer, writes:

This beautiful fish is a Leafy Seadragon, Phycodurus eques, was collected off the coast of Southern Australia in the 19th century. It beautifully resembles to the seaweeds amongst which it lives, with delicate leaf-like projections from its skin. The beauty of this specimen, suspended in alcohol and with an almost translucent appearance, is enough to draw me in. But when I started reading about the name on the label, this specimen held a fascinating history.

I work as the Interpretation and Learning Officer in the Museum, and part of my role is to develop the new displays as part of the Museum’s redevelopment. This is exciting and interesting work, exploring the collections for stories both biological and historical. With collections made by Darwin and Wallace, and specimens of animals that are now extinct, the  Museum is a treasure trove of amazing stories. Sir Edward Charles Stirling, the E.C.Stirling M.D. of the label on this specimen, was a Fellow of the Royal Society and of the Royal College of Surgeons. He was born in Australia, educated at Trinity College, Cambridge ad subsequently worked at St George’s Hospital in London before returning home. Back in Australia he entered into politics, and here was advocate for women’s rights, introducing a bill for women’s suffrage in 1886. He also believed in education for women, campaigning for them to be admitted to Adelaide University’s School of Medicine, and was involved with the State Children’s Council. He had a strong interest in Zoology, and became the Director of the South Australian Museum in 1884. He discovered the Marsupial Mole, and out cast of the giant marsupial Diprotodon is thanks to him. So here we have one specimen that has highlighted the history of someone with diverse interests and strong beliefs in equality ahead of his time.

This is just one story from the sea creatures in the Museum. To hear more, come to our Animal Bytes evening as part of the Cambridge Festival of Ideas and Curating Cambridge on October 21st, from 7pm-8.30pm in the Department of Zoology, Downing Street.

Bichir, Polypterus lapradii

Roz Wade, Education and Outreach Officer at the Museum of Zoology, writes:

Throughout my time studying Zoology and working at the Museum I’ve had a fondness for quirky animals. Animals with interesting adaptations, peculiar lifestyles, weird and wonderful morphology, or retaining striking primitive characteristics that are lost in their relatives. Polypterus is a fish that fits the bill, and has fascinated me since watching it “waving” its large, round pectoral fins in a fish tank in a museum years ago.

Polypterus is an air-breathing, freshwater fish from Africa. When it was discovered in the early 19^th century, naturalists found its classification a challenge – amphibian or fish? Lobe-fin or ray-fin? It is a ray-finned fish (the most diverse group of vertebrates on the planet. If you have a fish that isn’t a lungfish, coelacanth, or cartilaginous fish, you have an actinopterygian), but one that has retained many primitive traits. Take the scales – a thick, bony armour of interlocking rectangles covered in tough, shiny enamel. Although different in detail, this looks very similar to the shiny, enamel-covered scales of the osteolepidid fishes (a group of long-extinct lobe-finned fishes) I have spent many hours studying. Bony scales like these are found in many fossil ray-finned fishes too. Then take a look at the skull – from certain angles the mouth of Polypterus has the appearance of a faint smile about it compared with the down-turned mouth of most ray-fins. Add to this the unusual fins – a row of finlets along the length of the back, and wonderful, round pectoral fins – and you have, for me, an engaging fish. But the fish itself is not the only thing of note about this specimen, as I have been discovering in researching the new displays for the Museum.

This particular specimen was collected by John Samuel Budgett, a Cambridge zoologist and embryologist working around the turn of the 20th century.  Budgett went on four African expeditions, attempting to find the embryos he wanted to understand this peculiar fish and its position within the vertebrate story. Finally, on what would be his last expedition in 1903, Budgett was able to observe the earliest stages of development of Polypterus, of which he produced elaborate drawings. However, he would never present his findings himself. Budgett tragically died in January 1904 at the age of 31 from blackwater fever, a complication of malaria. He was not the only zoologist to lose their life in pursuit of this fish – Nathan Harrington of Columbia University who was searching the Nile for embryos of Polypterus, contracted what was described as Nile Fever in 1899, a disease that was to take his life in a matter of days at the age of just 29. In the new Museum we hope to tell the stories of the people behind the collections, including the hardships and risks they undertook to further our knowledge of the animal kingdom, as well as the fascinating scientific stories of the animals themselves.

(To find out more about the Museum redevelopment, visit the Museum of Zoology website)

Osteolepis macrolepidotus, a fossil fish from Scotland

Osteolepis macrolepidotus. Head is to the left of the image.
© University Museum of Zoology, Cambridge 2013

Roz Wade, Education and Outreach Officer for the Museum of Zoology, writes:

I was lucky enough to study Natural Sciences here at Cambridge, specializing in Zoology. Having the museum’s collections to learn from is the most amazing resource for a student. Being able to see the animals, explore how they are put together, getting the light-bulb moment of understanding of “ahhh that’s what that structure is”… I don’t think you can get that from a text book. Nothing beats looking in detail at the animals themselves.

When I was in the third year of my degree I did a research project with Professor Jenny Clack, the Curator of Vertebrate Palaeontology here in the Museum. She showed me this fossil fish over 380 million years old, from the Middle Old Red Sandstone of Scotland, and I was hooked on palaeontology. But fossils of that age are not rare. In fact, fish fossils from the Middle Old Red Sandstone of Scotland are not particularly rare. What is special about this fossil is what is preserved.

At first glance, this fossil looks like a jumble of scales, with no clear bones in the head and not even any fins preserved. But take a close look at the head and you can see that, although there are few recognisable bones there, what is preserved is something much more astonishing. What we can see here is the natural cast of the back part of the brain cavity and inner ear. Look closely at the lump of sediment in the middle of the head and you can see nerve canals branching off it. On either side are the beautifully preserved infills of the semicircular canals of the inner ear. These are the balance organs, and are surprisingly similar to the semicircular canals inside your inner ear that are telling you which way up you are. This is a very ancient sensory system – ears evolved first for balance, not hearing, and semicircular canals are seen in all vertebrates. The physics of the inner ear means that you can tell something about the sensitivity of these organs by looking at their proportions. So not only is it amazing these structures are preserved at all, you can also say something (albeit with many assumptions to cover aspects of the system not preserved) about what these creatures, which went extinct hundreds of millions of years ago, may have sensed.

The Silver Sea Bream: Chrysophrys auratus

Family Sparidae. F.2404: part of the skull

© University Museum of Zoology, Cambridge 2013

Professor Jenny Clack, Curator of Vertebrate Palaeontology at the museum writes:

This extraordinary bone forms the top of the head of this species of sea-bream. Many species of bream grow large humps on the top of the head, although this is an extreme example. Presumably the hump is a feature related to display between individuals. When I first saw this specimen I had no idea what it was: it’s one of the most bizarre modifications to the skull I have seen in any animal, and the bone is much more robust than you usually find in ray-finned fishes. It certainly deserved inclusion in our new Teleost exhibition. Only as I carried out research for this exhibition did it begin to make sense. The upper arrow points to the place where the nerve cord enters the skull to join the brain, and the lower arrow points to the place where the head joins on to the vertebral column (or backbone). There would be jaw bones beneath the ‘beak’ at the front. This species is found throughout Indo-China, and the specimen is part of the Macartney collection, purchased by the museum in 1836. (The old name Pagrus unicolor was found to be superceded by C. auratus.)