2022-09-06 P&E Agenda - Item 5 - Attachment 1 - Six Mile Creek Bridge Replacement Offset Report - TMR

2.4          Matters of national environmental significance that will
             not be impacted by the proposed action
Two MNES have been identified as potentially occurring in close proximity to the proposed action. However,
direct impact to habitat for these species will be avoided (refer Section 1.3, Figure 1.2, Figure 1.3 and
Figure 1.4). These MNES consist of the following:
   Mary River cod (Maccullochella mariensis) – Vulnerable
   Australian lungfish (Neoceratodus forsteri) – Vulnerable
Further details related to each of these MNES and potential impacts associated with the proposed action are
provided within the sections below.


2.4.1        Mary River cod

2.4.1.1      Ecological background
The Mary River cod is an elongate fish with concave head profile and protruding lower jaw. It is typically
golden-yellow, green or dark brown in base colouration, with an overlay of black to dark green mottling which
sometimes extends onto the grey or whitish ventral surface. Dorsal, pectoral, caudal and anal fins are clear
to dark, with dark mottling on their bases. This species typically grows to 70cm in length and a weight of 5 kg
(TSSC 2016). The Mary River cod is a carnivorous ambush predator that is known to feed on fish and
invertebrates.
The Mary River cod naturally occurs within the Mary River system, and there are three areas within the Mary
River system where cod are present (TSSC 2016). These are:
   Tinana-Coondoo Creek upstream from Tinana Barrage
   Six Mile Creek downstream from Lake Macdonald
   Upper Obi Obi Creek
Mary River cod form pairs and spawn annually around spring. Nest sites are selected and guarded by the
male. Nests are located in area associated with structures and may be formed in hollow pipes, snags, hollow
logs and other in-stream debris. The eggs are typically deposited as a layer inside the nest where they
adhere to the surface of the substrate. The eggs of this species are opaque, measuring between 3.0mm to
3.5 mm in diameter. Eggs typically hatch at the end of the fourth day after they are laid when the
temperature is 21°C. Newly hatched cod larvae are 5 to 7 mm long. The male continues to guard the brood
until they disperse to search for food around seven to nine days after hatching (TSSC 2016).
The Mary River cod inhabits high gradient, rocky, upland streams through to large, slow-flowing pools in
lowland areas. Anecdotal accounts by anglers and landowners often describe the ideal cod habitat as
comprising deep, shaded, slow flowing pools with plenty of snags and log-piles (TSSC 2016). The Mary
River cod is known to migrate into smaller tributaries from the main river in late winter. Depending on flows
and time of year the Mary River cod may move over 30 km up or down stream. The species is also known to
have a home range where fish may stay for a large proportion of time (TSSC 2016).
The main threats to the Mary River cod are impoundment of streams, loss of in-stream aquatic vegetation,
invasive fish, and overfishing (TSSC 2016).




                            Project number 511784 File Six Mile Creek - Matters of National Environmental Significance Report 2021-12-03 Revision 1   26