Native galaxias (Galaxias brevipennis and Galaxias maculatus)

Application for Scientific Permit – Available for Public Comment

Public comment on the following application for a Scientific Research (Fauna) Permit is open until 22 October​​ 2021


Applicant: Biological Sciences, University of Tasmania

Species/Taxon: Galaxias maculatus (common jollytail), Galaxias brevipinnis (climbing galaxias)

Location:

For Galaxias maculatus

Bowlers Lagoon (landlocked)
Ringarooma River (marine-migratory)
Tooms Lake (landlocked)
Tamar River (marine-migratory)
Rebecca Lagoon (landlocked)
Rebecca Creek (marine-migratory)

For Galaxias brevipinnis

Lake Plimsoll (landlocked)
Great Lake (landlocked)
Lake Pedder (landlocked) 
Snug Falls (marine-migratory)
Cygnet Creek, Swan River (marine-migratory)
Rebecca Creek (marine-migratory)

Title of research: Genetic divergence of landlocked marine-migratory galaxias populations

Aim of project:

'Landlocking' is the process that involves the loss of marine migratory life histories in species, such that they now complete their entire lifecycle in freshwater. Landlocking is considered a key process for the creation of new species in fishes, as landlocked populations are typically reproductively isolated from marine migratory populations.

Some species simultaneously exhibit 'landlocked' and 'marine migratory' populations, and their landlocked populations might be currently undergoing speciation given their reproductive isolation from marine-migratory populations. Ongoing speciation may be indicated by the level of genetic divergence between landlocked and marine-migratory populations: do landlocked populations exhibit greater genetic divergence FROM marine-migratory populations than that observed AMONG marine-migratory populations?

The aim of the project is to quantify the genetic divergence of populations within two species of galaxiid fishes: Galaxias maculatus and Galaxias brevipinnis. Both species exhibit landlocked and marine-migratory populations.

Justification: 
Galaxias maculatus and Galaxias brevipinnis both exhibit landlocked and marine-migratory populations, and their landlocked populations may represent examples of incipient speciation. If landlocked populations are genetically divergent they deserve separate conservation, otherwise ongoing processes for the generation of biodiversity may be impeded.

Maximum likely numbers of individuals involved:

Galaxias maculatus (common jollytail). 60
Galaxias brevipinnis (climbing galaxias). 60


Activities undertaken and methods:
FIELD-CAPTURE
Fish will be sampled by one of two methods that have been previously employed successfully on this species: electrofishing and fyke netting.

(1) Electrofishing uses direct current electricity flowing between a submerged cathode and anode. This affects the movement of the fish so that they swim toward the anode, where they can be caught. A backpack electrofisher will be used for this purpose. When a fish encounters a large enough potential gradient, it becomes affected by the electricity, with uncontrolled muscular convulsion resulting in the fish swimming towards the anode. The small size of galaxias (<130 mm) limits the size of the potential gradient that can be experienced across its body, such that they only receive minor influence from an electric field, and recover quickly.

Two people will perform the electrofishing. One person operates the electrofisher. The anode is a metal ring on the end of a wand. The metal ring is lined by a fine plastic mesh, which can be used by the operator to lift fish from the water (once the wand leaves the water, the electric current stops). The second person will carry a bucket contain 175 mg/L of Aqui-S to euthanise the fish humanely. The second person will also carry a dip net to assist in the collection of fish.

(2) Fyke netting uses fine (5 mm) mesh nets that are set overnight to passively catch fish. Images of the net are attached. Fish passively enter the net based on encountering the 'wings' of the net, and then enter capture chambers, within which movement is directed towards subsequent capture chambers, rather than in the direction of exiting the net. These nets also feature a plastic exclusion mesh at entry, to prevent access by larger animals (such as platypus, water rats, and larger predatory fishes). Fyke netting is conducted in low-flow environments. The net is set overnight, and collected in the morning. Fish are able to swim once within the net, and the net mesh is too fine for fish to become entangled. Fish will be euthanased by transfer to a bucket containing 175 mg/L of Aqui-S.

DNA sampling is only possible through taking a tissue sample from each individual. Our genetic analysis requires 1 µg of DNA, and our preliminary experiments indicate that non-lethal tissue samples (fin clips) do not provide sufficient DNA for our analysis. DNA sampling is crucial to meeting the aims of the study.

Fate of animals:
All individuals will be euthanased

Likely impact on species involved (including any by-catch):

The likely impact on these galaxias is minor. Both species are common throughout their respective widespread habitats in Tasmania.

Other species: electrofishing may stun other species of fish, but they will be readily identified and removed by at least 10 metres from the area of electrofishing, and on the other side of barriers such as rocks and logs, such that they should not re-experience an electrical current.

The fyke net has a plastic exclusion mesh at the entry to the net, such that platypus and water rats are prevented from entering. Other small fish may enter the net, but these will remain alive inside the net and will be released once the net is retrieved.



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