The story began on 11 February 2003, when the carcass was sighted west of Torbjørnskjær. Østfold County decided to bring the whale ashore, and it was transported to Fredrikstad for handling. Local authorities faced an unenviable disposal problem: options including sinking the carcass in the fjord, dispersing it with explosives, or burying it on land were all abandoned after the Norwegian Environment Agency raised concerns about groundwater contamination and uncontrolled dispersal of remains. A private initiative led by researcher Endre Hoeffeker offered a way out. With permits secured in coordination with the Environment Agency, Hoeffeker volunteered to take responsibility for the animal, sectioning it into manageable parts and incinerating the meat at a specialised facility for contaminated animal carcasses.

The initial cleaning took place at the Fredrikstad waste facility, where most of the flesh was removed. The bones, still bearing residual soft tissue, were then moved to Hoeffeker’s residence — a former school building four kilometres away with ample space for processing. To accelerate decomposition, he built a compost pile using horse manure as a bulking agent, a technique previously applied to cattle and whale remains. Manure introduces the microorganisms and nitrogen needed to speed breakdown, and while elephant dung is often considered the gold standard for such work, horse dung from a nearby riding school proved practical and effective. The method also carries a documented scientific bonus: microbial activity substantially reduces intraosseous lipids, effectively degreasing the bones from within. Untreated lipids are prone to oxidation and rancidification, which can cause odour, discolouration and dust attraction over time.

The next stage was maceration in a purpose-built 20-cubic-metre tank filled with a solution of two ordinary household products: OMO Color laundry detergent and Zalo dish soap, both chosen for their high enzyme content. Approximately 300 kilograms of each detergent were used, with a large portion supplied as sponsorship by the DeNoFa factory in Fredrikstad. The entire skeletonisation process stretched across 15 years, largely because the tank had no heating facilities. In 2018, facing the prospect of selling the school building, Hoeffeker donated the fully prepared skeleton to the Natural History Museum in Oslo, ensuring its preservation and public future. Notably, no research samples were taken during the process — soft tissues and body fluids are now lost — but the authors point out that Norway lacks any systematic sampling of stranded whales, and that most whale specimens in Norwegian collections entered museums opportunistically, through finders rather than organised collecting.

The museum seized the opportunity. Its new permanent palaeontology exhibition in Brøggers Hus was designed to narrate 520 million years of evolutionary history, from the Lower Cambrian to the present, with a distinctive emphasis on transitions between oceanic and terrestrial life. Professor Jørn H. Hurum recognised the 15-metre skeleton as the ideal modern anchor for the story of whale evolution — the journey from land-dwelling artiodactyl ancestors through transitional forms to fully pelagic species like the sperm whale, a trajectory the study describes as the poster child of macroevolution. The exhibit pairs the skeleton with fossils and casts from every stage of that transition.

Before mounting could begin, conservation work was needed. The skeleton had been stored for two years in containers at the museum’s offsite facility at Økern, where examination revealed that degreasing had discoloured the bones and that mould had grown on the skull in several colours. Conservators removed the mould with an industrial vacuum, ethanol and sandpaper, then applied a thin layer of bone-coloured antifungal acrylic paint across the entire skeleton to unify its appearance and prevent recurrence. An inventory also revealed six missing vertebrae — three thoracic, two lumbar and one caudal. These were replaced with corresponding vertebrae from another sperm whale specimen in the collection, CN248, which had been reduced by 40 percent along the parasagittal plane for an earlier wall-mounted display. The missing halves were reconstructed with epoxy paste, styrofoam and iron rods, then coated in the same acrylic paint, making the restorations nearly indistinguishable from original bone. All chemicals were first tested on isolated ribs from the same donor specimen before full-scale application.

The greatest engineering challenge was architectural. Whale skeletons are conventionally suspended from ceilings, which allows dynamic, anatomically lifelike poses and efficient use of gallery space. But Brøggers Hus is a historic building whose ceiling could not bear the full weight of a whale. The solution was a hybrid: a custom steel podium carries most of the load from beneath, while ceiling cables take only part of the weight. The podium’s steel chassis incorporates three vertical pillars of varying diameters — the primary load-bearer a 12-centimetre steel tube supporting a horizontal beam beneath the skull’s paroccipital processes, with 8-centimetre and 4-centimetre pillars holding curved plates and bars that cradle the palatal region and both jaws. The support structure was designed, certified and fabricated by Ekland Service Mekaniske Verksted AS, with certification confirming compliance with ISO 3834-2:2005 for load-bearing steel structures, and the scheme was consulted with Riksantikvaren, Norway’s authority for the conservation of historic buildings.

Assembly itself was a meticulous exercise in anatomy and mechanics. The skeleton was divided into four sections for transport, since the museum’s doorways were too narrow for anything larger. Thoracic vertebrae were threaded onto a central steel tube via lightweight aluminium discs, each featuring a central hole for the tube and threaded holes for headless screws; spray foam filled the gaps between vertebrae before a layer of epoxy simulated connective tissue. Each rib was drilled to a depth of 15 centimetres and joined to the vertebral column with 30-centimetre steel rods glued using diisocyanate, an adhesive absorbed by bone within two minutes of mixing, gaining the sturdiness needed to lock the rods in place. The flippers — the most delicate elements — were drilled axially to match their original anatomical positions and threaded with iron rods of varying thickness, with epoxy paste mimicking natural cartilage at every joint. Because the teeth risked being removed by visitors, each was drilled, screwed and glued into its socket with isocyanate, and the hyoid apparatus was anchored to a steel bar fixed between the pterygoid bones.

Installation in the exhibition hall proceeded in two phases: first the skull and thorax, moved on wheeled scaffolding and a pulley system with a three-tonne capacity, then the lumbar and caudal vertebrae, threaded individually onto the support bar with aluminium discs and ceiling cables distributing the load. The final caudal vertebrae were threaded onto a two-centimetre aluminium tube, chevrons were attached with wood screws and epoxy, and the pelvis was mounted on a T-shaped iron bar glued into the last lumbar vertebra. The result, unveiled in 2022, was an immediate success: the museum received 197,000 visitors that year, set new attendance records each month, was named Norwegian Museum of the Year in 2023, and was subsequently nominated for the European Museum of the Year Award 2025.

The project’s legacy extends beyond the gallery floor. In 2025, the team created a photogrammetric 3D model of the mounted skeleton from 2,795 photographs, producing a high-detail mesh of roughly 162.7 million vertices that was simplified to under a million polygons for online release on Sketchfab and MorphoBank. Such models serve research, conservation planning and public outreach, and — crucially — provide an accurate reference should the specimen ever need to be dismounted, moved or relocated. The study also adds rare material to Norway’s sperm whale holdings: only a handful of partial specimens exist in Oslo and Bergen, and this nearly complete skeleton significantly enriches the national record. For museums facing similar constraints, the authors offer a clear message — mounting large cetaceans within existing infrastructure demands early coordination between conservators and structural engineers, careful attention to material compatibility and reversibility, and controlled redistribution of skeletal mass to prevent mechanical fatigue over the decades a specimen spends on display.

Subject of Research: Preparation, skeletonisation and museum mounting of a sperm whale skeleton

Article Title: Preparation and mounting of a sperm whale ( Physeter macrocephalus Linnaeus, 1758) at the Natural History Museum in Oslo, Norway

Article References: Rojo, M. A., Delsett, L. L., Ruciński, M., Hoffeker, E. T. A., Lund, B., Bjerke, B. A., & Lønnve, J. E. (2026). Preparation and mounting of a sperm whale (Physeter macrocephalus Linnaeus, 1758) at the Natural History Museum in Oslo, Norway. Natural History Collections and Museomics, 3, Article e191751. https://doi.org/10.3897/nhcm.3.191751

Image Credits: AI Generated

DOI: 10.3897/nhcm.3.191751

Keywords: sperm whale, Physeter macrocephalus, Natural History Museum Oslo, skeleton mounting, museum conservation, composting, maceration, photogrammetry, whale evolution, osteology, structural engineering, Norway