Enclosure 6 - ESP Letter

                                                                                Ecological Service Professionals
                                                                                                          Sustainable Science Solutions




     Table 4        Calculation of oyster habitat area in the Noosa River Estuary

Oyster Area         Calculation                       Areal Surface Area                  Assumptions/Exclusions

A) Area with the    Area of Accommodation             Area of oyster habitat within       Given that estuaries in Florida also
potential to        Space - Based on current          historical harvest areas that       have everglades and occurs at a
currently           ambient water quality             should occur in Noosa Estuary       similar latitude to Noosa, the
contain oyster      (temperature, salinity & depth)   based on other similar system =     assumption that oyster reefs may
                                                                 2             2
habitat within in   the lower section of the          41,530 m to 207,650 m               have occupied 1-5% of the
the                 estuary, Lake Weyba and                                               accommodation space is considered
accommodation       Weyba Creek would have                                                reasonable.
space and           suitable conditions for oyster
historical oyster   growth. Based on above, the                                           The accommodation space and
lease areas         accommodation space for the                                           calculations includes areas within
                    entire lower Noosa Estuary                                            and outside the FHA in the lower
                                    2
                    (13,742,000 m ) minus area                                            estuary
                    outside historical oyster lease                                       Assumes oyster shell beds and rock
                    area (approximately                                                   / rubble areas are all suitable for
                                  2
                    9,589,000 m ) = Area within                                           recruitment (which based on current
                    historical oyster lease area                                          assessment they are not)
                    (i.e. excluding Lake Weyba)
                                 2
                    4,153,000m                                                            Assumes that oysters were not
                                                                                          dredged from Lake Weyba as we
                    If oyster reefs historically                                          have no record of an oyster lease
                    represent between 1 and 5%                                            there.
                    of the accommodation space
                    of an estuary, as found in                                            Based on two-dimensional surface
                    Florida, then oyster beds and                                         area of the estuary. Actual three-
                    reefs in the Noosa estuary                                            dimensional calculation of area of
                    within the historical oyster                                          the channel surface would be
                    lease area (1 to 5% x                                                 greater than this although all
                                 2
                    4,153,000m )                                                          calculations based on two
                                                                                          dimensional areas so would be
                                                                                          proportional.

B) Peak annual      The number of live oysters        Conservative estimate of the        Estimated size of live oysters
harvest area        exported from Noosa River in      surface area required to meet       harvested (to derive number per
from Noosa          any year ranged from 2 to 6       live harvest records for a single   bag)
River based on      million individuals, multiplied   year at the peak harvest =
fisheries           by the maximum density of
                                                              2  -1
                                                      8,241m .yr assuming highest         Unknown quantity of dead shell
records             oysters known from restored       density (the surface area           harvested from the system (likely to
                    reefs elsewhere in the world of   harvested annually for live         be several times this surface area
                                      -2
                    728 ± 102 ind. m (Casas et        oysters would range from            given that dead shell extends below
                    al. 2015)
                                                              2
                                                      2,409m and to 9,585 m .yr
                                                                               2   -1     sediment surface)
                                                      depending on live oyster density    Unknown density of oyster
                    Calculation of the area to meet   in the estuary which is unknown)
                    a single harvest year =                                               beds/reefs in the Noosa Estuary due
                    maximum density x maximum         This is the area required meet a    to historical extraction of dead shell
                                          -2
                    harvest = 728 ind. m x 6          single annual harvest. Total area   from soft sediment areas, therefore
                    million live oysters harvested    that once had live oysters would    maximum density known has been
                                                      be greater than this due to the     used.
                                                      length of time required to          Likely that harvest occurred across
                                                      regenerate reefs between            multiple areas due to the need for
                                                      harvests, i.e. the same habitat     oysters to regenerate. Based on
                                                      area cannot be harvested in         modern cultivation techniques, it
                                                      successive years                    takes 2-3 years for oysters to reach
                                                                                          harvestable size.
                                                                                          Dredged oysters (which contributed
                                                                                          to the historically recorded harvest)
                                                                                          were likely much less dense than
                                                                                          those collected by hand from
                                                                                          intertidal and shallow beds based on
                                                                                          historical account (Smith 1981).

C) Current          Surface area of all dead oyster   Minimum area of dead oyster         Due to the extensive presence of
extent of dead      habitat identified in field       habitat identified consisting of    bare sediment throughout the
                                                                                     2
or buried Oyster    assessments, based on visual      buried oyster bank – 9,679 m        estuary, we were not able to
beds/rubble         inspection, sediment probing      and functionally dead shell beds    surveyed extensively for oyster shell
                                                                 2            2
habitat             and handheld GPS location.        – 7,171 m = 16,850m                 or rubble due to survey time
measured in                                                                               constraints, so the current extent is
Noosa River                                                                               the minimum known. Oyster shell
within Historical                                                                         buried under sediment near

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