So just how will zoos fit a hippo on the balance sheet?

Wedged between the bearded pigs and the camels lives Thug, the 13-year-old pygmy hippo and one of the star attractions at London Zoo.

But one place you won’t find the 300kg West African is on the zoo’s balance sheets, where the difficulty in valuing the exotic animal has resulted in Thug receiving a nominal value of zero.

This situation may be about to change. On 19 June, the Accounting Standards Board released new accounting guidelines which attempted to tackle the age-old practice of leaving precious, but otherwise priceless, artifacts and artworks off balance sheets.

While aimed predominately at museums and galleries, the implications could flow on as far as London Zoo’s penguin pool where animals are left off accounting records or accounted for at nominal levels.

The test comes down to whether the animals can be defined as being held for ‘knowledge and culture’, which, according to the ASB’s project director Alan O’Connor, they can.

‘You have situation where the entities’ greatest assets are not reflected on the balance sheets,’ he says.

O’Connor says the new rules encourage zoos to be more transparent, but also acknowledges that some assets are plain near impossible to value. ‘You would hope that [the new rules] might encourage them to show more transparency,’ he says.

The consequences for zoos may be that they have to show ‘stewardship costs’ or the costs associated with maintaining the ‘assets’.

‘The disclosures should provide readers with an understanding of the asset values being reported as well as the entity’s policies for managing its total holding of heritage assets,’ the new rules state.

The ASB’s stated aim is to increase transparency. When he announced the new rules, ASB chairman Ian Mackintosh said that under the current practices ‘many museums and galleries publish accounts that do not adequately reflect the collections that they exist to safeguard and preserve’.

O’Connor says each zoo has a slightly different approach to the accounting dilemma.

Bristol Zoo assigned a value of £1,000 for its collection of more than 7,000 animals. At London Zoo, the animals are not represented on the balance sheet at all, instead they are described as gifted.

Other nations adopt a similar approach. Australia’s Taronga Zoo values its collections at $1 (50p) per animal but considers the collection ‘part of a regional and international collection and not the specific property of the institution’.

O’Connor also struggles to see how some accounting rules could be interpreted in the zoo environment. Difficult questions include how, for example, can acquisitions and disposals be equated into births and deaths, or how are asset lives calculated. ‘We know what the likes of a giraffe or a lion is, maybe you could come up with a useful [asset] life but how useful is that to the reader,’ he says.

London Zoo declined to comment.