Mysterious oarfish washed ashore

Seldom seen, the rare, elongated oarfish, measuring between 3-8 meters from nose to tail, is a likely source of myths about sea serpents. Recently, a 4m long specimen was found washed up at Bokkomsbaai in the Western Cape by a commercial fisherman, Keith Boas. This ribbon-shaped, brilliant silver fish which has irregular blackish streaks and spots on its body and crimson dorsal and pelvic fins, is seldom seen far from the deep sea and is believed to be the longest bony fish in the ocean.

After it was found, the fish was taken to Fransmanshoek Conservancy at Vleesbaai for safe keeping where Ricco Menezies and colleagues from Cape Nature in Stilbaai maintained it in excellent condition. It was cleaned and blast frozen at Viking Fisheries and thereafter transported to the South African Institute for Aquatic Biodiversity (SAIAB) in Grahamstown for preservation. SAIAB is a Research Facility of the National Research Foundation (NRF).

SAIAB’s Senior Aquatic Biologist, Roger Bills, injects formalin into the flesh of the oarfish to speed up the preservation process and ensure that the internal tissues and organs are ‘fixed’ so that they do not decay.

“These fishes are seldom caught and they are mostly seen when washed ashore,” said Dr Stephen Lamberth, Inshore Resources Researcher from the Department of Agriculture, Forestry and Fisheries. They are found in temperate and tropical oceans worldwide. They live in deep water and are rarely seen.

Unlike other fishes, the oarfish keeps its body straight and swims vertically in the water column. This movement makes it easier to spot prey silhouetted against the light from the surface. “They are a mystery to scientists and are commonly found to depths of 100metres and more where they feed on crustaceans and fish larvae,” added Lamberth.

On its arrival, the 4metre long deep water fish provided hours of fascination for curious SAIAB and the Department of Ichthyology and Fishery Sciences (DIFS) staff and students from Rhodes University. SAIAB and DIFS maintain strong relations as a large number of DIFS students are supervised by SAIAB.

The fish is soaked in a bath of 10% formalin to be disinfected and ‘fixed’. This retards decomposition. With large specimens such as this, formalin is also injected into the flesh to ensure that the internal tissues and organs are also fixed and do not decay.  Once fully ‘fixed’ the specimen will be thoroughly rinsed and transferred into a storage bin containing ethyl alcohol. The SAIAB Collection has five other specimens of this species dating back to 1966. Tissue samples taken from the oarfish will be stored in SAIAB’s Biomaterials Bank for DNA sequencing. The oarfish specimen will be stored in SAIAB’s Collection Facility and will be used for research. This state-of-the-art storage facility is specially designed for the long-term preservation of aquatic specimens.