A 100,000-litre tank with a coral reef? Is this the right "habitat"? Should sharks be restocked?
A few days ago, the female blacktip reef shark, Else, died at Hellabrunn zoo at around 20 years of age. Three years ago, her mate of the same age, Kurt, died. Since then, Else swam her laps alone through the 100,000-litre tank with its coral reef. For 18 years, Hellabrunn was the "habitat" of the two sharks.
If Hellabrunn's own reports are to be believed, restocking (introducing a replacement shark or sharks) is currently being coordinated with the coordinator of the European Studbook for blacktip reef sharks.
What is the life of a blacktip reef shark like in such an aquarium?
Born in an aquarium, there are only two possibilities for the offspring: Either the mother is separated from the other sharks for several to many weeks, usually in very small areas of the aquarium, so that the mother and offspring do not fall victim to the other sharks during and after birth. Or the mother remains in the aquarium and the lives of the newly-born sharks, and sometimes also the mother, are ended very quickly. They literally become a "shark snack" for the other blacktip reef sharks, including the father. Nature has designed things in the oceans so that the mother retreats to shallow reef areas or near mangroves, where she gives birth to her young, protected from conspecifics. The walls of an aquarium, however, are finite! Even the mother's inhibition to eat her own young (which is hormonally induced during birth) subsides very quickly, meaning that in a small aquarium tank they can indeed fall victim even to their own mother.
If the young survive this initial period of danger, they are admitted to the "conservation breeding programme". This term suggests that these animals are protected through breeding programmes in zoos. The status of the IUCN Red List of Threatened Species is often cited to point out that many shark species are threatened, and that breeding programmes should therefore be viewed positively. This is a myth: blacktip reef sharks (Carcharhinus melanopterus) cannot and must not be reintroduced into the wild, which means they can never be released into the open oceans.
Therefore, captive breeding serves only one single purpose: to restock sharks in the tanks of European zoos.
Furthermore, even this is only minimally successful: it was only in 2014 that blacktip reef sharks were successfully bred in an aquarium for the very first time.
The only positive aspect of this is that sharks in zoos are not taken from the wild. Europe's busiest aquarium dealer operates in the Netherlands, offering almost any wild catch and delivering them (with exceptionally high mortality rates).
Blacktip reef sharks do not possess active respiration: they cannot "pump" water. Instead, they must swim forward so that water flows through their gills, allowing them to breathe. Unlike nurse sharks, for example, they suffocate if they cannot swim. They are therefore completely dependent on the aquarium's counter-current technology. If the technology fails, there is an acute danger of death, with no other tangible means of rescue than restarting the system.
Moreover, the tanks are usually far too small. The 100,000 litres in Hellabrunn correspond to a tank size of 10 x 4 x 2.5 metres. For an adult blacktip reef shark with a length of 1.6 metres, this is equivalent to a solitary cell in a human prison: in the wild, they roam an area of several square kilometres. Unfortunately, there are no legally regulated minimum requirements for keeping sharks, not even for zoos.
Finally, sharks are intelligent animals with complex social behaviour. Blacktip reef sharks also have a hierarchy and know "friend and foe". It can certainly happen that they fight for dominance and injure each other in the process. Restocking with sharks is therefore always a risk, which ultimately always occurs at the expense of the animals.
Blacktip reef sharks swim mindlessly in circles in aquariums, injure themselves or each other on the corals or walls, and eventually die – often prematurely: in the ocean, these sharks can live up to 40 years; in aquariums, the lifespan is often significantly shorter, sometimes only half as long. As was the case with Kurt and Else.
Therefore, ElasmOcean appeals to cease the deliberate breeding of blacktip reef sharks and the restocking of them in aquariums or zoos. This shark species does not belong in an aquarium.
