Thursday, 18 February 2016

Successful fish survey in the North Pine River

A fish survey I conducted in the North Pine River last weekend was productive, with seven different species being found in a quiet stretch of water alongside Mungarra Reserve.

Common silverbiddy, Lawnton.
Most numerous were estuary glassfish (Ambassis marianus), a native species which studies suggest is just as good at controlling mosquito larvae as the introduced eastern mosquitofish (Gambusia holbrooki), also present.

Another mosquito predator occurring in smaller numbers was the Pacific blue-eye (Pseudomugil signifer); between these fish species and recent aerial spraying, not a single mosquito bothered me all afternoon.

The river at this location is close enough to the ocean to be tidal, but far enough upstream to have low salinity, with the riparian vegetation being comprised of regular trees and not salt-tolerant mangroves.

This kind of habitat is often used as a fish nursery for marine species, where juveniles can dwell in relative safety until they are ready for the challenges of life downstream near the river mouth and bay.

As a result, small (<15cm) yellowfin bream (Acanthopagrus australis) were common in the main channel, and a young common silverbiddy (Gerres subfasciatus) was caught in a fish trap set near the vegetated river margin. Perhaps my favourite discovery however was a school of tiny striped scat (Selenotoca multifasciata) found sheltering beneath a submerged branch, shown below.


Edit: The fish in the photo at the top of this post had originally been identified as a glassfish, but Tim Howell, who runs the Facebook page 'Wildlife of Noosa', correctly identified it as a silverbiddy. Thanks Tim!

2 comments:

  1. Nice post - do you just net the fish?

    Cheers - Stewart M - Melbourne

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    Replies
    1. Thanks Stewart! I use a variety of techniques, outlined here: http://wildbrisbane.blogspot.com.au/2015/02/fish-watching.html

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