Basking sharks in aquaria

This is something I've wondered for some time. Whale sharks have been thriving at Georgia Aquarium and an aquarium in Japan, if not a few more, I don't know. If an exhibit is big enough, like Georgia's Ocean Voyager, could it be possible to house at least a couple of basking sharks? Diet shouldn't be an issue considering the whale sharks and manta rays eat krill and other small animals just fine in human care, and as stated, being only the second largest fish, it is entirely possible for an exhibit of a good size to be built for basking sharks. The only issues I'm aware of for keeping these fish is catching them from the wild and of course, animal rights people protesting keeping them. Are there any other issues that have kept big enough aquaria from housing basking sharks?

 

Has it even been attempted? I can't say I've ever heard of any.
Hypothetically an aquarium in a cool climate that pumps natural seawater through could possibly solve the climate problem, although for a tank large enough for Basking the pumps would need to be pretty hefty.
I don't think enough is known regarding the overall biology to justify attempting it. Given the typical survival record for other large pelagic sharks in captivity I would suspect it might be similar. Indeed Basking Sharks are closer relation to the Great White and the makos than to the Whale Shark. I believe of the order Lamniformes only Carcharias taurus and the Odontaspis species have been successfully kept in captivity.

 

Has anybody tried keeping basking sharks in captivity?

 

I'm not aware of it ever having been attempted, but suspect it would be comparable in difficulty to keeping whale sharks. Two main problems are temperature (there are no huge ocean tanks kept in the temperature range preferred by the species) and that no aquarium, at least in the western world, would/could "sacrifice" some individuals to learn how to keep the species long term. In the early history of whale shark keeping they rarely lasted long; it took quite some years and attempts before the basics in keeping the species were solved. I doubt the other lamniforms can be used for predicting how easy/hard it would be to keep basking shark. We're at order level, i.e. the relationships are distant, and their behaviours are very different. Sand tiger keeping says little about mako keeping despite both being lamniforms.

Depth and pressure is unlikely to be an issue for basking shark. Much remained unknown or speculative until quite recently, but we now have several studies of movements especially by Atlantic basking sharks. They clearly point to movements that depend on food and temperature. When swarms of their food, especially copepods, become numerous in coastal waters off NW Europe, basking sharks appear. When they disappear in the winter, so do basking sharks. During the winter, basking sharks mostly occur in the 200-1000 m depth range (but with records from near the surface to 1500+ m), often moving hundreds of meters up and down in 24-hour patterns that match the diel or reverse diel migration, in which copepods and similar zooplankton dominate. They can also move quite rapidly between various depths. For example, during the late summer, a northeast Atlantic basking shark moved from shallow water to more than 1250 m in just two days, then returned directly to 200-600 m where it moved up and down in a diel pattern during about a month, and then moved back to shallow water. It has now also been confirmed that some whale sharks follow the diel migrations, revealing that this tropical/subtropical species periodically can occur in quite cold waters.

Basking sharks are strongly associated with temperatures of 7-18 Celsius and this is also reflected in their movements. Those off Atlantic USA tend to move south to subtropical/tropical waters in the winter, but at mesopelagic depths that match their temperature preference. In the northeast Atlantic, southward movements tend to be more limited, and instead they stay in regions affected by the relatively stable Gulf Current, on occasion even crossing the Atlantic (as evident by the couple of records of individuals moving between the British Isles and Atlantic Canada).

In the thread mentioned above, someone asked about Greenland shark. It was attempted several years ago by a Canadian aquarium, but it failed, likely in part because they had to resort to a quite large (although still immature) individual. More recently, the closely related and very similar Pacific sleeper shark appeared in a Japanese aquarium, but it was an accidental bycatch from quite deep water and already in poor health at its arrival. The problem is that the only places where reasonably sized (aka transportable and likely to adapt to captivity) Greenland/Pacific sleeper sharks regularly are caught in fairly shallow waters are in remote arctic regions where transport is irregular and unreliable.