Blog

Sharks on the Slab

By: Mark McGrouther, Category: Science, Date: 11 Apr 2014

Sally and Amanda spent several 'aromatic hours' earlier this week processing shark specimens.

Sally with Sharks

Mark McGrouther © Australian Museum

On Monday night, two large, plastic-wrapped parcels were extracted from the depths of the fish freezer. On Tuesday morning, after a night spent thawing on the large, stainless steel sink in the appropriately named wet lab, the parcels were opened by Sally and Amanda. One contained a Harrisson's Dogfish from Lord Howe Island and the second contained two small hammerhead sharks caught off Sydney.

The Harrisson's Dogfish from Lord Howe Island was of great interest. This species has had a tumultuous past, having been significantly overfished along the upper continental slope of SE Australia, populations are now primarily restricted to Seamount habitats.

Conservation issues for this and related species have led to the closure of the Seamounts to trawling but the good news, according to research by Research Associate Ken Graham, is that while still vulnerable to fishing pressure, the populations numbers are stable. Additionally with specimens turning up at Lord Howe Island the species maybe more widespread than initially thought.

This is only the second specimen ever collected from Lord Howe Island so the fish was registered and muscle tissue added to the frozen tissue collection. This important location links the known populations of Eastern Australia with the Norfolk, Three Kings and Kermadec Ridges, which will allow for research into possible cryptic speciation.

Tissues were also taken from the two Smooth Hammerheads. A sample of skin was removed from one specimen.  This will be examined under the Australian Museum's scanning electron microscope.  Images will be added to the Shark and ray scales gallery as they become available.

All three specimens are now being preserved in a large tank of formalin. They will soon be transferred to the tank area for long term storage. Details of their capture, size, storage location and other information were added to the database.

While the specimens were being processed, I emailed an invitation to other staff to visit the lab.  A number of people poked their noses in, but perhaps not surprisingly commented that they could follow the fishy aroma once they arrived on the fish floor... apologies to our non-fish colleagues who work nearby.

Tags Sally Reader, Centrophorus harrissoni, Harrisson's Dogfish, Centrophoridae, Smooth Hammerhead, Sphyrna zygaena, fishes, ichthyology,