Conservation of a museum megamouth shark specimen by changing its preservative from aqueous ethanol to aqueous glycerol

The Western Australian Museum’s iconic 5.2-m megamouth shark (Megachasma pelagios) was relocated 20 km from Perth to the Maritime Museum in Fremantle for treatment in an exhibition gallery. A 70% ethanol solution was diluted to 16% before the glass lids of the fiberglass tank were removed to facilitate removal of the heavy shark. A custom-made stainless steel storage and exhibition tank containing 8,000 L of 30% glycerol solution was prepared inside the exhibition space prior to the arrival of the specimen. Portholes in the top sections provided access points to record the density of the solution using a digital densitometer. The density fell linearly with the logarithm of the immersion time. Equilibration was achieved after the solution showed no change in density for a period of 2 months. To increase the glycerol concentration, 2,000 L of the solution were decanted into storage tanks before the same volume of pure glycerol was added. This process was repeated four times to reach a final level of 62% during the 2.5-year conservation program. The color and flexibility of the shark improved and dehydration wrinkles from ethanol storage were significantly reduced.