HUSBANDRY AND RESEARCH

Observations on the Grey seal

at Aberdeen Zoo Halichoerus grypus

G E O R G E L E S L I E Manager, Aberdeen and North of Scotland Zoological Society, Scotland

Part of Aberdeen Zoo is, naturally enough, devoted to an exhibition of Scottish birds and mammals, including a fine seal colony of four Grey seals Halichoerus grypus. One male and two females were brought down from the Orkney Islands during past culling seasons, and the fourth animal, a five-year old bull (who is dominant) was brought into the zoo when approximately one-and-a-half years old. I t has been caught accidentally in an off-shore salmon net locally and its neck was badly damaged; one particularly deep wound, where the nylon netting had cut into the skin, encircled the neck entirely. Although it healed remarkably quickly, there is still a one inch deep groove to be seen, especially if the seal has been lying out and is dry.

When the seal was brought into the zoo, it refused to stay in the seal pool or surrounding area (and as the surrounding wall is only 0.5 m (18 in) high, there was little to stop it getting out). It also refused to eat. After four days, and the loss of approximately one third of its body weight, we decided to start force-feeding.

The head keeper straddled the seal and opened its jaws, using heavy gloves. I t was fed four times a day on I kg (2 lb) of herring per feed. We have noticed that in force-feeding seals, if the fish’s dorsal fin is towards the right hand side of the seal when it is swallowing it seems to exper- ience less difficulty in getting it down. This par- ticular seal started feeding on its own seven days after force-feeding had commenced. We have also noticed that once seals have settled down and started feeding on their own, they never leave the pool or surrounding area.

When the seals from Orkney arrived (at an age of about 5-6 weeks) they were put directly into the pool, where they floundered about for a few minutes before starting to swim. After five min- utes they emerged from the pool. These seals - like others received direct from the breeding grounds - had never seen live fish, and they accepted dead fish when offered. At first they

were given z kg (4 lb) of herring per day, but we gradually increased this to 3.5 kg (7 lb) by the time they were six months old. White fish (cod and whiting) has been offered from time to time since, but has always been left in preference to herring. We have now fed them on herring for three years with excellent results.

After 14 days the seals could be approached with safety, and were tame enough to be hand fed.

Although no trace of worms has been found in our colony, we have had to treat seals with worms on many occasions. These seals are ones that have been brought to the zoo, either by fishermen or by the Aberdeen Association for the Preven- tion of Cruelty to Animals. Those that have been found well up on the beach have been found to be suffering from worms, and ulcerated lesions of the mouth. They have usually been in a very emaciated condition.

We formerly treated them with antibiotic injections and a dewoming product administered orally. We force-fed them on arrival with z or 3 herrings 4 to 5 times per day; and within a week they gained about one third of their body weight, and were ready to start feeding on their own. Very sick seals took longer to start feeding by them- selves - usually between 10 and 15 days. One young seal took seven weeks. We have noticed that when seals start steaming when lying out of the water, and look bright about the eyes, they are ready to start feeding on their own.

Half the seals found exhausted on the beaches have had one or both eyes badly affected and various eye ointments have been tried with little success. The best method of treatment seems to be to bathe the eyes gently with clean sea water. I f the seal starts to feed itself before the eyes have re- covered, its herring is put into a small bath of salt water, so that by removing the fish it bathes its own eyes. Recovery is rapid.

During the 1969-70 (October-March) seal season we have had a number of seals brought in, and have treated them with Thybenzol

204 HUSBANDRY AND RESEARCH

administered with a Thybenzol drencher. The dosage, related to body weight as applicable to sheep, was administered in triplestrengh. Wehare

White whales

at Duisburg Zoo Delphinapterus k w a s

W. G E W A L T Director, Dnisburger Tierpark .4.G., Germany

The only two B'hite whales Delphitiaflterirs lrucas on exhibit outside the United States are now at Duisburg Zoo. After the inauguration of our Delphinarium (the only Oceanarium for Bottle- nosed dolphins Tursiops trimcatus in Germany) Duisburg now has the first Walarium. This is a large open-air, artificial seawater pool, equipped with a filtering and cooling system. The pool, which measures z o x 1 2 ~ 4 m ( 6 j x 4 0 ~ 1 3 f t ) , can be cooled to 2'c (36"~) even on a hot summer day. However the temperature is normally kept at 10% (50'~). The salinity is 37".

Capture, acclimatisation, and transport of the two whales from Hudson's Bay to the zoo was carried out by L. Reimann and myself with the assistance of a team of Canadian whalers, in- cluding Eskimoes, Cree and Chippewyha Indians. On 4 and 5 August 1969 the animals were isolated from a herd of about 800 whales by means of canoes, driven into shallow water and caught by hand. Placed on mattresses, wrapped in wet towels and given an injection against stress and infection, they were brought to the camp on the coast 64 km (40 miles) away, where a small Fortable swimming pool had been prepared for them. There, the two whales, a male and a female, were thoroughly examined and accustomed to feeding for a fortnight. They \%ere also injected with vitamins. The whales became tame in an extremely short time; after only four days they came to the edge of the pool in order to be caressed and hand-fed. However, they always rejected the fish which we gave them as food so we had to use force-feeding. Every day the pool was drained to a level of 50 an (18 in) and about 20 fish, each the size of a large herring, were pushed into the whales' mouths.

found recovery by this method far more rapid, and no worms have been seen in the faeces the following day.

After heavy water-tight crates, big enough to hold strong canvas stretchers had been con- structed, the whales were loaded aboard the chartered plane on the evening of 17 August 1969. Each whale was slightly more than 2.5 m (9 ft) in length, and the complete crate with one whale weighed rather more than 914 kg (I ton).

The crates were filled only about 22 cm (9 in) deep with water, in order to avoid extremely high transport expenses. Throughout the whole flight, which lasted about 18 hours, this water was poured over the whales, which had been wrapped in towels, in order to keep them moist. We also used a large quantity of ice cubes to cool the whales.

On the evening of 18 August the aircraft reached Diisseldorf airport and was at once forwarded to the Walarium at the zoo. The animals reached their final quarters in good con- dition.

Here they are fed with 20 to 70 herrings or mackerel daily. These contain gelatine capsules containing liver oil, mineral salt and vitamins. The female soon learned to collect all the fish thrown into the pool, and after 29 months she learned to swim to the diver and accept fish from his hands. The water level was lowered to I m (3 ft) in order to allow him to stand in the pool for this purpose. The male was shyer and we had to force-feed him for four months. It is possible that the whales might have accepted hand-feeding sooner, if we had kept them short of food, but we would not take this risk and force-fed them at least every second or third day. Unfortunately, doing this meant that we lost a large quantity of our artificial seawater each time.