Jens is unlocking information about how and where largetooth sawfish spend their lives through the chemistry of their teeth. The long, toothed rostrum for which sawfish are named might hold some answers about where a sawfish grew up, where it moved, how fast it grew during each period of life, and how its place in the food web changed as it grew. That’s because rostral teeth lay down chemical traces throughout a sawfish’s life. The low numbers of living sawfish mean that Jens is looking at ways to use historical specimens in museums to develop insight into the fine details of the lives of sawfish.
I am an aquatic ecologist interested in the importance of fish migrations to aquatic ecosystems and conservation. I grew up in the Palouse region in north-western USA, in a small, rural farming town nearly 300 miles (480 kilometres) from the coast. Despite this distance, my region is deeply tied to fish migration and the ocean. Salmon migrations in the nearby rivers stretch 500 miles (805 kilometres) into the Rocky Mountains and have been an important piece of the cultures of our region for millennia. Perhaps this helped influence my choice to return to the Palouse region to pursue...
The objective of this study is to use the chemical records stored in archived rostral teeth to uncover important details of how sawfish spend their lives. Our aim is to show that rostral teeth store the movements sawfish make and changes in their place on the food chain over their lifetime.
The results of this study are important because we know very little about sawfish behaviour and ecology. There are so few living sawfish that learning this information by tracking and studying living sawfish is difficult, and knowing what sawfish did in the past is useful for conserving them now. If we can recover this information from rostral teeth in museums, we can unlock a trove of details that would otherwise be impossible to discover.
Sawfish populations declined worldwide well before scientists realised how threatened they were and before their ecology had been studied in detail. Because there are so few living sawfish, some scientists say it is unlikely we can learn a great deal more about their life history from living fish. But this missing ecological information is also key to conserving sawfish species, so we need creative minds and new tools to find ways to uncover it. To do this, some scientists are mapping genetic diversity and population structure using the genetics of rostra found in museums. Tools to uncover life history and migration – among the least understood areas of sawfish ecology – from archived rostra would also be useful. Our research team have indicated that this might be possible. In a small sample we showed that the rostral teeth of largetooth sawfish preserve the chemical record of the sawfish’s movements and life history in the same way that the hard parts of some other fish species do. These chemical techniques have revolutionised how we study migration and movement in other kinds of fish, and we hope that this discovery can help us learn more about sawfish too.
If this technique works on a larger sample of rostral teeth, the results could be important for sawfish conservation. What we could learn from rostral tooth chemistry can’t be gleaned by other methods. Our work has already shown that rostral teeth store movement from fresh to salt water and it suggests that rostral teeth may store even more details about location and habitat. The physical structures inside rostral teeth might also give us clues to how fast the sawfish grow and how old they are. All of this could be an important source of information that helps to conserve the sawfish we still have.
The aim of this study is to uncover important information about the movement and ecology of largetooth sawfish in Brazil using the chemistry stored in 131 archived rostral teeth we have collected. By achieving the following objectives we hope to reconstruct where a sawfish grew up, where it moved, how fast it grew during each period of life and how its place in the food web changed as it grew. These details are currently not very well understood, so the results of this study could help us understand where and how to best protect sawfish.
Outside the USA, The Bahamas is the only place where Critically Endangered smalltooth sawfish can reliably be found. Tristan wants to ensure that protection measures in The Bahamas are understood and enforced as far as sawfish are concerned to close the current gap between policy and the people. He’ll be using aerial surveys, sonar and BRUVs, combined with interviews that draw on local knowledge, to identify essential sawfish habitats that need protection. Engaging with the community through workshops and by training students and meeting with government, Tristan intends to advocate for smalltooth sawfish protection throughout The Bahamas’ territorial waters.
Steven and Kevin are using genetic techniques to understand how Caribbean reef shark populations are connected across the extent of their range. Populations of this Endangered shark are in decline generally, but where they are managed and there is effective protection, their numbers are stable. With the integration of the correct information, Steven and Kevin are convinced that we can give Caribbean reef sharks a better shot at recovery and population stabilisation. They will also explore any barriers to connectivity, looking to the future recruitment and recovery of these sharks.
With very little information available about Endangered sicklefin devil rays, their seasonal aggregations at sea mounts in the Azores give Sophie an opportunity to learn more about their lives. She will be collecting satellite-tracking data that show how they move in the Azores’ exclusive economic zone. The information she collects will be used to develop maps of how the rays are using the zone and to identify essential areas that multiple species use. With this information at hand, Sophie hopes her work can contribute to a network of marine protected areas.