Are seals willing to pay for access to artificial kelp and live fish?

Abstract: Environmental enrichment (EE) is used to improve the wellbeing of animals in human care. One way of testing what resources an animal prefers to have access to, is to make it pay a price. The price is in the form of time or energy spent to get access to the resource. When measuring the motivation of animals it is useful to compare the resource which is to be evaluated to a resource with a known value. Food is often the comparator. The maximum price paid approach measures the highest price an animal is willing to pay for access to a resource. In this study the motivation of a grey seal (Halichoerus grypus) for getting access to artificial kelp and live fish was measured. Food was used as the comparator. A large net cage with a weighted entrance and a nonweighted exit gate was used as the test arena. The seal had to enter it by opening the entrance gate which had increasing weights every day, in 10 steps up to 65 kg. The seal was not willing to pay any price for the live fish. The maximum price paid for the food was 60kg, and for the artificial kelp 10kg, i.e. 17% of the maximum price paid for food. The results suggest that neither live fish nor artificial kelp was an attractive EE for this seal. However, the study also shows that spring (reproductive period) is not a good time to test motivation in grey seals.