Posted on Jul 04, 2016

Finding, but not keeping, Dory

On the 29th of July the much awaited sequel to “Finding Nemo”, “Finding Dory”, will be released in the UK. Unless you were hiding under a rock it would have been impossible to miss the success of “Finding Nemo”. The story centred on a clownfish (anemonefish) trying to get home after being taken from a reef. The goal of the movie was to portray the message that fish are better off left in the wild. Rather unfortunately it is ironic that this film caused the demand for anemonefish in the aquarium trade to rise dramatically as each child wanted their own “Nemo”.

Fortunately it is possible to breed anemonefish in captivity. However, the increase in demand following “Finding Nemo” was such that captive breeders could not keep up with the pace, and pressure on wild populations increased. This caused populations in some areas to become extinct. Decreases in anemonefish populations can be directly attributed to collection pressure as studies have shown that populations in areas which are closed to fishing and collection are as much as 25 times larger than in unprotected areas (Jones et al. 2008).

Now, with the imminent release of “Finding Dory”, scientists and conservationists are concerned that the film will cause an increase in demand for “Dory” or regal tangs (Paracanthurus hepatus). Unlike anemonefish it is not possible to breed tangs in captivity because they are pelagic spawners. Anemonefish ‘glue’ their eggs to rocks or a reef which then hatch into self-sufficient fry. Tangs, on the other hand, release their eggs into the open water and when these hatch they have no mouth, eyes, gastrointestinal tract or nervous system. Breeders have yet to figure out how to rear these embryonic fish and keep them alive. Consequently, every “Dory” sold must come from the ocean.

If demand for these colourful, charismatic fish increases, as it did for anemonefish, the collection pressure on the wild populations may have devastating effects. Regal tangs have a large distribution within the Indian and Pacific Oceans but are already under threat from illegal collection. The most common method of catching tangs is illegal and uses cyanide to stun the fish, making them easy to collect. This method also kills the surrounding coral reefs and other marine life.

We believe that enthusiasm for these characters should be directed not towards collection, but conservation – looking after the species’ natural habitat and protecting them in the wild.

In short, don’t find a Dory.

Image: H.Krisp

Jones, A.M., Gardner, S. and Sinclair, W. (2008) Losing ‘Nemo’: bleaching and collection appear to reduce inshore populations of anemonefishes. Journal of Fish Biology 73 753-761

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      Knowledge Hub Finding, but not keeping, Dory