Interview with Dr Paul Cowley, Principal Scientist, SAIAB (South African Institute for Aquatic Biodiversity).
Mossel Bay, South Africa, February 24, 2016: Dr Cowley has vast experience in the field of aquatic ecology and alongside his role as Principle Scientist, he is an honorary professor and Research Associate at the Department of Ichthyology and Fisheries Science at Rhodes University. He also serves on the editorial board of the African Journal of Marine Science and is a member of the Ocean Tracking Network’s (OTN) International Scientific Advisory Committee. He recently traveled to Mossel Bay to work with Oceans Research at a national fishing competition where he acoustically tagged some of the sharks and rays caught. Today we chatted about his career, while fishing for white steenbras for his acoustic tagging project.
Q1. What is the Ocean Tracking Network (OTN)?
A1. OTN is a Canadian-based global programme aimed at improving our understanding of the movements and migrations of marine animals using acoustic telemetry technology. When the project started they were looking for partners around the world and I put up my hand for South Africa. That was the beginning of something that’s grown immensely. It all started at a conference where someone queried why astronomers and other science disciplines manage to carry out mega projects, but in ocean science we never have mega projects. During the discussions where the global network of receivers was proposed, I suggested there’s a huge opportunity to study migration biology in South Africa because of our situation. Located on the tip of the African continent and positioned between two Oceans (Atlantic and Indian) our coastline is characterized by incredibly high diversity of marine animals, of which many are endemic to this region. Most importantly we also host the greatest shoal on earth… the annual sardine run, which witnesses the migration of millions of fish, sharks, dolphins and birds each year.
Q2. How are you involved in OTN?
A2. Ever since I pitched the idea to place receivers around the South African coastline, I have been involved with OTN and I am now also a member of their international scientific advisory committee. We have also formalised the South African link to the OTN and called it the ATAP (Acoustic Telemetry Array Platform). The concept is very similar to what OTN have set up but on a much smaller (local) scale. We have several node sites equipped with listening stations (acoustic receivers) from Hout Bay on the west coast to Ponta do Oura at the Mozambique border.
Q3. Did you pick these sites because you know there’s a good chance of capturing migration patterns, or because it’s spread out evenly?
A3. Two reasons: firstly, we choose sheltered sites as sea conditions can be very harsh so we decided on bays which would provide some protection for the equipment. The other very fortunate reason is that there are researchers at these sites who are very keen on being involved and they have become our deployment collaborators e.g. Oceans Research are the collaborators for Mossel Bay and manage the deployment of the receivers at this site. We provide new receivers at set times which they deploy and we take the old ones away for refurbishment and to download the data. So Oceans Research provide us with manpower, boats and equipment for deployment. We would never logistically be able to manage all these sites ourselves so rely on these key partners.
Q4. How did you end up in science and research?
A4. I was always fascinated by fish. Wherever I went as a boy, whether it was to sea, to a river or dam, I was always fishing or turning over rocks, fiddling around in the water. My career path was decided a long time ago. I turned my love for fish and fishing into a career.
Q5. Do you think you were always going to go down the science route when it came to a career in fish?
Q5. I think I was always trying to answer the questions, especially the ones that play on an anglers mind. For instance we are here today fishing at a site that looks perfect, but where are all the fish? My passion has always been to find out where they are so my research focused on fish movement behaviour is really me living a childhood dream.
Q6. If you had to stick to one or the other, would you choose fresh or saltwater species for your studies?
A6. Saltwater, without a doubt.
Q7. Do you have a passion for both or mainly just saltwater species?
A7. I think mainly saltwater, due to the diversity we have in South Africa. We have a rather depauperate freshwater fish fauna in South Africa and from an angling perspective, they are all alien species such as carp, bass and trout. There are, however, a few species I’m really interested in such as yellowfish and we are currently planning to do a telemetry project on them.
Q8. Are they easier to catch than today’s Steenbras are proving to be?
A8. The smallmouth yellowfish are fairly abundant and easy to catch but the largemouth yellowfish is quite rare, but we’ve found some places where they are quite abundant and they are big fish… around 10kgs.
Q9. What’s your absolute favourite aquatic species?
A9. Dusky kob [Argyrosomus japonicus]. It’s an aggressive predatory fish but can be very aloof. I love fishing with artificial lures and it’s my favourite species to hunt using lures. It’s an ambush predator that will use even a little rock or a depression in the sandy bottom to wait for an opportunity to pounce on its prey. So when fishing for them you really have to “read” the water to understand where the fish will be hiding. As you walk along the beach you’re constantly looking for the best place to cast and it’s an incredible thrill when you get it right. That’s what really drives me when it comes to lure fishing.
Q10. What has been your most important scientific finding?
A10. It’s very difficult to identify a single discovery as most of the research I have been involved in is of an applied nature, largely looking at the biology of fishes and how this can assist with the management of over-exploited species, such as white steenbras and dusky kob.
Q11. Have there been any surprises?
A11. Yes – there have been many surprises. Pretty much every fish species we have studied has yielded some surprises. Probably the most striking surprise is the discovery of how resident certain species are. For example, I once recaptured a young white steenbras on an exposed sandy beach at the exact same spot where it was tagged and released two years earlier. It’s amazing to discover how resident certain reef fish are, for example we’ve recaptured the same bronze bream 5/6 times at the exactly the same spot over a period of several years.
Q12. So there aren’t too many nomadic species?
A12. Although residency appears to be dominant behaviour, particularly by reef fish, we have also had our migration surprises. For example, a shad (elf) that was acoustically tagged and monitored for one year in Langebaan Lagoon was recaptured two years later just north of Durban. Certain species migrate, such as leervis (Garrick) that undertake an annual winter spawning migration to KwaZulu-Natal, which coincides with the sardine run. Nomadic behaviour, however, is difficult to describe but I think that some individuals of most species are nomads (i.e. do things differently). Typically a species will have a dominant behaviour (e.g. are resident) but there’s always some portion of the species that are nomads or will travel great distances.
Q13. Why do you think certain individuals do this?
A13. I think that’s almost like a safety net in terms of survival. Food, shelter and reproduction are the most important things for an animal to survive and ultimately persist as a species. So if all individuals did the same thing it would mean that they have all their eggs in one basket, which is not a good strategy. Estuarine fish are really interesting and vulnerable. They spawn at sea then come into the estuary as babies, spend the first couple of years of their life in estuaries and they are very dependent on that environment. They rely on these nursery habitats for food and shelter but they get hammered before they reach sexual maturity (adulthood). In some cases we’ve lost more than 50% of the fish we have tagged in a single study.
Q14. Do you have an understanding of what happens to them?
A14. They are caught by anglers. Because they are dependent on estuarine nurseries they are extremely vulnerable to fishing pressure. There’s no commercial fishing in estuaries, so the harvesting is mostly by recreational anglers. Most of the fish caught in estuaries are illegal in terms of size limits e.g. a dusky kob’s minimum size limit is 60cm, but they start leaving the estuaries at this size. So the majority of dusky kob caught in estuaries are juveniles. This is why we do these projects, to be able to inform the fisheries management where enforcement is needed. We are keen to educate anglers on how the future of fishing is in their hands. Since most of the fish caught in estuaries are undersized anglers are obliged to put them back, so we teach best practices in terms of handling and caring for fish to ensure that they survive. It is pointless practicing catch-and-release if the fish don’t survive. The anglers themselves have to look after the resources that will soon run out. Like this fishing competition we’re involved in… we encourage the catch-and-release rule and best handling practice so the fish have a high chance of survival. That’s where a lot of my work has been focused, on working with the management teams of these fishing competitions.
Q15. Do you find that the fishing competition management teams listen?
A15. Very much so. They have benefited from our involvement and a lot of the fisherman actually enjoy having the presence of scientists. There is a feeling of being more ‘green’. I have also been involved with the tackle industry. We started an initiative called ‘CARA’ Catch and Release Angling and we got a few of the tackle suppliers to only offer prizes to catch-and-release competitions and refuse prizes for catch-and-kill competitions. In some cases, even better prizes are offered for catch-and-release competitions with scientists present. Competition organisers benefit from having us as marshals as it means they have to provide less manpower for measuring the fish, the anglers benefit from having better prizes and the fish benefit from best handling practices being in place.
Q16. Has there been any resistance from the anglers to these changes in rules?
A16. At first, definitely, as they wanted to keep their catches. However, they soon realised that they’re still going to get the prizes and that they don’t have to deal with dead fish onboard.
Q17. So the role you take in these competitions, is it just marshalling?
A17. For this competition I asked if I could tag along (pardon the pun) as I knew they would be catching a lot of fish and we wanted to tag some for our study, so for this event we are guests. For other competitions we’ve actually been involved in the management of the competition, setting the rules and ultimately having the final say. For example if someone handles a fish poorly then we can disqualify that catch as we have set up the rules in such a way that they have to be handled carefully.
Q18. Will you continue to be involved in these competitions?
A18. We do a fair amount of tag and release ourselves currently. However, we are keen to tag more sharks and rays, which we know are a main target during these competitions so we want to be involved so we can tag more sharks and rays. We’d love to be profiled at all these events. These species will be caught anyway so rather we utilise these events to tag and also safely release the sharks and rays.
Q19. Do you think the stress caused is worth the data you get out when it comes to tagging and releasing?
A19. Yes definitely. There are actually separate projects currently taking place to also monitor stress levels of fish. There will be other scientists present at the next big competition we’re attending in May taking samples of fish to test blood and chemical properties to ascertain stress levels.
Q20. What information do you hope to acquire from the species tagged at these fishing competitions?
A20. There is so little know about the migration biology of all these species we’re tagging. We don’t know where they’re going, where they breed etc. For example, yesterday we tagged only female smooth-hound sharks. This is a species that’s known to display sexual segregation and we barely know anything about it. At least now we have 15 smooth-hounds with transmitters in Mossel Bay and we hope to identify movement patterns from our receiver network e.g. they might be permanent residents or move out of the bay for a couple of months a year – time will tell.
Q21. The bull ray tagged yesterday, is it resident in Mossel Bay?
A21. Nobody knows. It is the first acoustically tagged bull ray in South Africa and now we have a chance to find out more about its movement patterns. I think we’re going to be blown away by what we learn. The options are either extreme residency or long-shore migration. Or possibly even a return migration.
Q22. How will the data collected help science?
A22. A lot of the sharks we’ve tagged are threatened species e.g. there are around 70 white sharks with transmitters and that can feed into gaining a better understand to ensure conservation strategies are in place to protect them. One thing we’ve learned about white sharks is that they travel up to Mozambique… in South Africa they’re protected but in Mozambique they are not. It makes the laws in place in one country obsolete if they’re crossing the border into another country and getting killed. So we then know where to concentrate our conservation efforts to ensure that proper management is in place. For many of the bony fish species, an understanding of where they are resident is important for establishing marine protected areas.
Q23. How important is conservation to you?
A23. Every proposal I have ever submitted has had a strong focus on conservation. You can’t just study an animal without considering the impact that people have on that animal. It’s either conservation or management… we typically use the word conservation if it isn’t exploited but are affected by other impacts, but when it comes to fisheries impacts then we use the word management. Conservation and management are definitely a high priority.
Q24. How does your involvement in the fishing competitions tie in with conservation?
A24. It gives us an opportunity to engage with the public. We know from our fisheries surveys there are major problems with users in terms of compliance and low enforcement effort. These competitions gives us a fantastic opportunity to engage with our target audience. The people that really can make a difference.
Q25. Is there an opportunity to move away from weight based awarding at these competitions to reward skill?
A25. There has already been a fundamental change in the format of fishing competitions. Fish are now measured and are no longer subjected to being weighed. For this they were often hooked through the gills to be attached to scales, which can cause a lot of damage. They now measure the length of the fish and use a chart (length-weight relationship) to determine weight.
Species tagged during the fishing competition:
|Duckbill [bull] ray||1|
In total Oceans Research has tagged (in less than a year):
|Duckbill [bull] ray||2|
|St Joseph shark||1|
Oceans Research and their interns work with Professor Cowley and his team to help with the tagging and safe release of marine species caught at a number of these fishing competitions.
For information on Oceans Research internship opportunities, visit: www.oceans-research.com