Trawl net deployment. Photo by T. Lamb

Many weird and wonderful fish and invertebrate species inhabit the waters surrounding Heard Island and McDonald Islands (HIMI).

Some of these species are important prey for the land-based marine predators in the region, so knowing where they occur and in what quantity is important for managing and conserving the integrity of the ecosystem.

A book to assist Convention for the Conservation of Antarctic Marine Living Resources (CCAMLR) observers in the identification of benthic invertebrate bycatch in the HIMI region has been developed: “Field identification guide to Heard Island and McDonald Islands benthic invertebrates: a field guide for scientific observers aboard fishing vessels”

Research trawls

A trawling program was undertaken as a component of the marine science voyage conducted by the Australian Antarctic Division over summer 2003/04.

During the trawl program a midwater trawl net was used to catch fish and larger invertebrates, and a plankton net was used to catch the smaller zooplankton.

Trawls were conducted from the surface down to depths of 600 metres. The trawl data will be analysed in comparison with the acoustics, oceanographic and predator tracking data to see if large scale patterns in abundance and distribution of fish and invertebrates influence the predators’ choice of foraging areas.

Jellyfish of the Periphylla genus. Photo by A. Constable

One of the most interesting invertebrates commonly caught during the voyage was the very large jellyfish of the Periphylla genus. These jellyfish are known for their extremely large size - one reasonably intact specimen that was laid out on the ships trawl deck reached 5 metres or more! (see picture to right)

Idiacanthus atlanticus (bottom) and a species of Stomias (top). Photo by A. Constable

Some of the deeper trawls in water depths of 300 to 600 metres yielded very strange looking deep-sea fish with large teeth and distendable lower jaws (see picture to left)