Due to some heavy lifting by the Arthur Rylah Institute (ARI)  captive breeding of the critically endangered Glenelg Freshwater Mussels (Hyridella glenelgensis) is being trialled for the first time.  All bad puns aside, this important work ultimately aims to help recover the mussels and prevent their extinction.

Four Glenelg Freshwater Mussels. Source: Tim Fernando
Mussel with strand of glochidia poking out. Source: Tim Fernando

Glenelg Freshwater Mussels are only known from the Glenelg River catchment in southwest Victoria. They occur in shallow, narrow, flowing sections of stream with coarse sandy sediment, instream woody habitat and dense streamside vegetation

With a very restricted distribution, they are vulnerable to habitat degradation, low water flows, introduced species and bushfires.

ARI’s Timothy Fernando and Tarmo Raadik recently collected a small batch of mussels and ‘host’ fish from the Glenelg River system for the breeding trials at ARI’s aquarium.

Timothy Fernando showing off a Glenelg Freshwater Mussel. Source: ARI
Raadik and Fernando collecting specimens. Source: ARI

How do mussels reproduce?

Mussels have an interesting lifecycle. Their larvae (glochidia) attach to the fins or gills of fish, providing a surface to grow on and allowing them to move elsewhere. They eventually detach from the fish and the juvenile mussels burrow into the streambed.

Fin with glochidia attached. Source: ARI
Glochidia up close. Source: ARI

What progress has been made so far?

After a few days in the aquarium, the female mussels began to produce a foamy looking white strand. This is the glochidia, which were able to attach to a few host fish. Since then, more mussels have started producing strands of glochidia!

The scientists have been using Variegated Pygmy Perch and Common Galaxias to carry the glochidia on their fins and gills. There are now dozens of fish with baby mussels on board.

Common galaxias carrying glochidia. Source: ARI
Pygmy Perch carrying glochidia. Source: ARI

They’ll remain on the fish until they’ve fully metamorphosised. ARI scientists are still closely watching to determine how long this will take – they are estimating days or weeks.

Once the glochidia have dropped off the fish, the fish and mussels will be returned back to their homes in the Glenelg River system.

If juvenile mussels survive, it’s hoped they will form the founding population at the Victorian Fisheries Authority’s state of the art conservation hatchery currently being built at the existing Snobs Creek facilities. Further research will be undertaken to analyse growth rates, husbandry practices and breeding cues, to help form a larger picture on the species’ conservation.

It’s exciting that this is all uncharted territory, and so much is being learnt which may apply to breeding other native mussels in captivity.

Glenelg Freshwater Mussel producing glochidia. Source: ARI

This initiative a part of the 10inTen program, an effort to recovery threatened fish, crayfish and mussels. It has been funded by contributions from Victorian and Commonwealth government, including the Victorian Fisheries Authority and the Victorian Environmental Water Holder.

Listen to expert Dr Tarmo Raadik discuss past conservation efforts for the species:

Featured image: Glenelg Freshwater Mussel producing glochidia

Photo credit: Arthur Rylah Institue

Subscribe now for quarterly updates on Finterest articles