18. Feb, 2016

The shark in captivity

Keeping sharks  in million liters tanks has become  a ‘must’ to attract  a lot of  visitors  to an aquarium.  For example, the famous Georgia Aquarium is a public aquarium in Atlanta, Georgia, USA.  It  houses several thousand species, all of which reside in 10 million US gallons of marine and salt water. For long  it was  the largest aquarium in the western hemisphere.  But then in 2012 it was surpassed by Marine Life Park in Singapore.  Both aquaria also have sharks swimming around  behind large panoramic windows,  creating for the visitors the impression  that they are actually among them in the ocean. They are also the place to take your kids to  in the week-end. They will love it, watching the sharks while clutching daddy's or mummy's hand.

 https://en.wikipedia.org/wiki/List_of_captive_shark_species

But many species of  sharks don’t seem to do very well in captivity. One factor could be  the stress of transportation.  Restricted space  could also play a role,  although  modern saltwater aquariums have  a great deal of room to move around.  Nevertheless, many sharks end up dying within a year after their capture. Even the species that  are released  after a while in the open sea have difficulty with surviving longer than one year.  Best chances for survival  have smaller more docile sharks like catsharks and nursehounds and epaulette sharks. Probably beacuse these species are more territorial.  And even some larger species like sand tiger and leopard sharks. Some of  the geater aquaria also managed to keep tiger sharks in life for several years.

The larger a shark species can grow, the less likely it is that they will successfully survive in captivity.  Recently, a female Great White Shark reached a new record; surviving 44 days in a million-gallon tank housed at Monterey Bay Aquarium in California, eating four pounds of salmon, mackerel and one sardine (see picture).  But following its release it died a week later.  Some weeks   ago,  another  showcase of a  great white  shark  held  in captivity in an aquarium in Okinawa  also died shortly after its delivery by  fishermen who caught  it in their nets. http://wetpixel.com/articles/great-white-shark-dies-after-3-days-in-captivity-in-okinawa-aquarium

Why do sharks do not well in captivity?  Like the goldfish  in the litte pond on my balcony, some  of which must now  have reached the age of twenty years, and still seem to enjoy their little biotope. This is their world.  

Not so with sharks. One reason could be the restriction of their migratory  range. Most predator sharks swim  hundreds  of kilometers within a matter of days. This exercise and freedom is essential to their contentment. Another factor could be that sharks, unlike dolphins and orca’s, have a limited capacity to interact with humans. Probably because they are the offspring of a different  and  much older branch of  the evolutionary  tree of species that depend on inborn reflexes to survive in that great ocean.  http://www.sharks-world.com/sharks_in_captivity/