Marine Produce Australia: Cone Bay Barramundi Aquaculture ...

5. Marine Environmental Management Program
5.1 Assessing the EQG
The EMMP has been developed to monitor for potential impacts downstream of the sea-cages,
and at the boundaries of the moderate (MEPA), high (HEPA) and maximum (MaxEPA)
ecological protection area boundaries. The approach has two purposes: (i) to measure the
extent of the contamination gradient downstream of the sea-cages and (ii) to provide
relevant data for assessment of the EQG.
Integral to this approach is the collection of data at fixed distance intervals downstream of
the sea-cages. While this approach is designed for application in the MEPA on an incoming
tide (when water flows east), the sampling program also enables inferences about possible
effects on an outgoing tide (when water flows west). Under an outgoing tide, some (or all) of
the distance intervals may be inferred to be in the HEPA. EQG for high and moderate
ecological protection (or both) will therefore be applied depending on the position of the seacages
relative to the MEPA/HEPA boundary. Application of the EQG for high protection will be
applied where sea-cages are located less than 200 m from the western MEPA/HEPA
boundary—with the rationale that, on an outgoing tide, some or all of the gradient sites,
could be inferred to lie within the high ecological protection area. This is a conservative
approach that ensures protection of sensitive fauna located at/or near the edge of the
western MEPA/HEPA boundary. Further details regarding the application of the EQG,
particularly those related to distance interval sites, are provided below.
5.1.1 TSS and LAC
Sample medians will be calculated twice: once, after each sampling occasion and then again,
following the completion of the four month sampling period. Assessment of the EQG at the
completion of each sampling occasion allows for reactive management in response to ambient
effects (larger scale); whereas, assessment of the EQG at the end of the extended sampling
period allows for management of site specific effects (smaller scale).
After each sampling occasion
At the completion of each sampling occasion, TSS and LAC values obtained at the HEPA and
MaxEPA boundaries respectively will be pooled and the sample median calculated (n=4).
Similarly, at the completion of each sampling occasion, TSS and LAC values obtained at
gradient sites will also be pooled and the sample median calculated. However, because the
gradient sites may be inferred to be in the MEPA and/or the HEPA (see discussion above),
assessment against the EQG will be undertaken as follows:
� Where sea-cages are positioned greater than 200 m from the western MEPA/HEPA
boundary 14 (such that all sites are positioned in the MEPA, irrespective of current
direction), the median shall be calculated from pooled values obtained across individual
sites (0 m-200 m) (n=5) and compared against the EQG for moderate protection.
� Where sea-cages are positioned less than (or equal to) 200 m from the western
MEPA/HEPA boundary (meaning some or all of the sites are inferred to be in the HEPA),
medians shall be calculated separately e.g. MEPA - 0 m, 10 m and 50 m (n=3) and HEPA
- 100 m and 200 m (n=2). MEPA and HEPA site medians shall be compared with the EQG
for moderate and high protection, respectively.
� Where sites are inferred to be in the MEPA and the HEPA, as in the above example,
medians should not be calculated if the number of sites is less than n=3 (as a minimum of
three samples is required to derive a meaningful estimate). In this case, additional
samples shall be obtained such that the number of measurements is at least n=3. 15
14 Distance calculated from the sea-cage cluster centroid.
15 At the time of writing, sea-cages were positioned on the western MEPA/HEPA boundary (Figure 2.1). While seacages
are located in that position, medians will be calculated from n=5 measurements and compared against the
EQG for moderate and high protection. Comparison against the EQG for moderate protection will cover potential
effects on an incoming tide, whereas comparison against the EQG for high protection will cover inferred effects in the
high ecological protection area on an outgoing tide. Where practicable, future fallowing of sea-cages will ensure seacages
are positioned at least 200 m from the western MEPA/HEPA boundary, so that issues with sample size (as
described here) can be avoided.
36 Oceanica: Marine Produce Australia: Cone Bay Barramundi Aquaculture, Environmental Monitoring & Management Plan