Cockrone Lagoon Aquatic Biological Survey-Final Report (PDF File ...

Australian Aquatic Biological Pty Ltd
5. Results and Discussion
Please note that results listed here reect the species at that site at that time. Over time during
different conditions different species or numbers may be present.
5.1. Crustaceans
5.1.1. Freshwater Craysh.
Prior to this research project only Euastacus australasiensis and Euastacus spinifer were recorded
from the Gosford LGA, neither was known to occur within the Cockrone Lagoon catchment
and these two species were specically searched for. Additionally, coastal habitats in NSW are
known to contain two undescribed species of freshwater craysh of genus Tenuibranchiurus and
Gramastacus and these were also targeted.
Survey No.:100056-1 of Wamberal Lagoon identied two species of craysh in that catchment,
an endemic species Gramastacus sp and an invasive introduced species Cherax destructor. Both
these species were specically searched for in the Cockrone Lagoon, Winney Bay and Copacabana
catchments.
Both Wyong LGA to the north and Gosford LGA to the south represent a signicant freshwater
craysh distribution area. Though the knowledge base is small there seems to be a cut off line
roughly running from Wamberal Lagoon, through Narara and then up through Central Mangrove
that represents a species distribution line with one species (Euastacus spinifer) occurring on both
sides, two species (Cherax setosus and Gramastacus sp) only north of the line and one species
(Euastacus australasiensis) only south of the line. This project will map that line and the distribution
of these craysh species along the line, and the surrounding region. A scientic manuscript on
those ndings is proposed.
No craysh species at all were found within the Cockrone Lagoon, Winney Bay and Copacabana
Catchments.
5.1.2. Euastacus Craysh
We were unable to conrm the presence of either E. spinifer or E. australasiensis. It would be our
conclusion that the area is unsuitable for both species as the tributary creek system is too small
and without sufcient highland catchment to support the clean, clear permanently owing creek
systems preferred by these species.
5.1.3. Gramastacus Craysh
No craysh have been collected within any of the catchment areas surveyed. Suitable habitat areas
were found but too small to sustain viable populations.
5.1.4. Cherax
Yabbies Cherax destructor were not
found within the catchment. This was
a good sign and it is hoped that better
education will keep them out. Their vivid
colours make them popular aquarium pets
but unfortunately uneducated or uncaring
people release them into the wild creating
major environmental problems.
Figure 4. An aquarium blue yabby
Cockrone Lagoon Catchment Aquatic Biodiversity Report 13