Save our Seas Foundation ©

Interview

with James Lea (film Older Than Trees)

With his research on sharks, marine biologist James Lea has contributed to the establishment of marine protected areas. We asked him five questions about his work.

How do we know that some form of sharks and rays are older than trees?

We know that some form of shark has existed for more than 400 million years thanks to the fossil record. Although sharks have soft cartilaginous skeletons that don’t fossilise well, their teeth and denticles (tooth-like armoured plates on their skin) do fossilise well and are clearly present in the fossil record more than 10 million years before trees, which didn’t appear until around 390 million years ago. Amazingly sharks also predate dinosaurs in the fossil record by almost 200 million years, and outlasted them by surviving four mass extinctions!

How do get the necessary data about sharks and how much time does it take to be able to present valuable results?

It’s firstly very challenging to get data on sharks, and then when you do it’s a whole different story making sense of it all. Sharks mostly exist beyond our ability to observe them directly – underwater and out of sight – and so we have to use different technologies to track their movement and behaviour. A very popular one is satellite tags, but these can only communicate when the tag is at the surface, creating either very patch data and often very large datasets. It’s then very much like a puzzle, where you have to reconstruct the shark’s movements based on how it matches up with water temperature, available depths, timings of sunrise and sunset etc. This also requires a lot of processing power, so we now rely heavily on programs to crack these data black boxes for us and help reveal the secret lives of sharks.

Save our Seas Foundation ©
Save our Seas Foundation ©

How fast does one see improvements for the ecosystem when marine protected areas are established?

We tend to see different changes at different times scales, but generally it takes quite a few years for us to start seeing a good recovery. There is a very good example from a protected area in Mexico called Cabo Pulmo, which is well protected and has had great recovery, but it actually took more than a decade for the sharks in particular to really start and recover properly. This is because they have such slow reproduction compared to so many other fish – they take many years to mature, and then only have few young every year or two. But once and area does start to recover, the whole biomass in general really starts to increase and start to return to a proper healthy ecosystem.

Should people visit marine protected areas? How much tourism can an area tolerate?

think it very much depends on the location and how it’s managed as to what can be considered a sustainable level of tourism. For many species tourism has great potential to offer alternative livelihoods for people while also funding the management of MPAs, and there are some countries that have created shark sanctuaries based on the value of shark tourism to the economy. So it has tremendous conservation potential, and people should certainly favour ecotourism operations that support protected areas. But also look out for signs about how well they are managed – for example check for codes of conduct about how to interact with animals, are there limits on numbers of boats or people in the water, and is it clear how funds can feed back into local conservation initiatives and capacity building.

Save our Seas Foundation ©

What are the biggest challenges in your work as a marine biologist?

The single biggest challenge is how to combat overfishing – the greatest threat to sharks is quite simply that we are exploiting them much faster than they can reproduce. So yes, getting the data to show what needs to be done is a difficult, but the real challenging is changing peoples hearts and minds so that they actually want to make the changes that need to be made. So it’s definitely the most difficult step to convert science into real, meaningful change. But what gives me great hope is that there is a growing change of momentum in favour of shark conservation measures, which was recently exemplified by more than 140 species of shark now being listed on CITES, which restricts international trade and now covers more than 90% of the fin trade.

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