7

Auckland Inlet

AREA 1.33 km2
 Overall Result

Auckland Inlet is a tidal inlet that connects to the Inner Harbour through a complex of small streams meandering through mangrove-lined mudflats that are often inundated at high tide. Seawater extracted from Auckland Creek is used to cool the Gladstone Power Station. Stormwater run-off outlets are located along Auckland Creek.

This zone has five water and sediment monitoring sites, one fish monitoring site, one mud crab monitoring site and one mangrove monitoring sub-zone.

Water & Sediment

Grading system
A
Very good (0.85-1.00)
B
Good (0.65-0.84)
C
Satisfactory (0.50-0.64)
D
Poor (0.25-0.49)
E
Very poor (0.00-0.24)
 
Data not available

Water & Sediment Quality Results

Water
Sediment

Water quality
Auckland Inlet received an overall water quality score of 0.85 (A). This score was based on the scores for physicochemical (0.87), nutrients (0.71) and dissolved metals (0.99).

Sediment quality
Sediment quality of Auckland Inlet was very good with an overall score of 0.93 (A).


Measures Results

Water
Sediment

Auckland Inlet received a very good score of 1.00 for pH indicating that the average pH was well within the guideline value range. This zone received a good score for turbidity (0.74) indicating that average turbidity was below the guideline value.

All six dissolved metals received very good scores (0.93–1.00) indicating that average concentrations were well below the water quality guideline values.

Auckland Inlet received a good overall score for nutrients (0.71). Total phosphorus had a good score (0.73), total nitrogen had a satisfactory score (0.55), and chlorophyll-a had a very good score (0.85), indicating that average concentrations for these measures were below the guideline values for this zone.

Habitats

Grading system
A
Very good (0.85-1.00)
B
Good (0.65-0.84)
C
Satisfactory (0.50-0.64)
D
Poor (0.25-0.49)
E
Very poor (0.00-0.24)
 
Data not available

Mangrove Results

The overall zone score for Auckland Inlet was 0.65 (B) indicating a good condition for mangroves in this zone. This score was similar to the score of 0.68 recorded in 2018.

Mangrove extent (0.76) was good and canopy condition (0.57) and shoreline condition (0.62) were satisfactory.

Fish and Crabs

Grading system
A
Very good (0.85-1.00)
B
Good (0.65-0.84)
C
Satisfactory (0.50-0.64)
D
Poor (0.25-0.49)
E
Very poor (0.00-0.24)
 
Data not available

Fish Health Results

Harbour Score
Visual fish condition (VFC) 0.74
Fish health assessment index (HAI) 0.90

Visual Fish Condition: Harbour Score
FVA - Fish Visual Assessment
FBC - Fish Body Condition
Fish Health Assessment Index: Harbour Score
HAI - Health Assessment Index

Fish Health (Overall):

The overall score calculated for fish health in 2021 was 0.82 (B), which is an average of the scores for Visual Fish Condition 0.74 (B) and the Health Assessment Index 0.90 (A).

Visual Fish Condition:

The overall score for the visual fish condition is an average of 0.97 (A) for Fish Visual Assessment (FVA) and 0.50 (C) for Fish Body Condition (FBC).

The high scores for FVA are a result of a low incidence of poor visual health. All fish species assessed for this metric received very good scores ranging from 0.94 (A) to 0.98 (A). This result was similar to the HAI scores for external measures where a very low number of external health issues were recorded.

The satisfactory score for FBC in 2021 was a result of poor scores for yellow-finned bream (0.47) and pikey bream (0.48). Both species assessed had a mean body condition below the long-term average (2003 – 2020). However, the remaining three species assessed all had satisfactory scores ranging from 0.54 to 0.55.

Fish Health Assessment Index:

The overall HAI score for Gladstone Harbour was 0.90 (A).

This was comprised of scores from five fish species, barramundi 0.98 (A), barred javelin 0.90 (A) and blue catfish 0.81 (B), bream 0.98 (A) and mullet 0.81 (B).

In general, the surveyed fish species showed very few signs of external health issues, a similar result to the Visual Fish Condition sub-indicator. Scores for internal organs were also low indicating good to very good fish health.

Fish Recruitment Results

Zone ID Score
7. Auckland Inlet 0.63

Fish recruitment was assessed for two species: yellow-finned bream Acanthopagrus australis and pikey bream Acanthopagrus pacificus. The overall score for 2021 was 0.62 (C) similar to the 2020 score of 0.64. The final scores were measured against a 2012 to 2020 baseline. The 2021 score for fish recruitment indicates a season with higher recruitment rate (increased catch rate) relative to the mean reference level determined over the baseline period. The total number of bream caught in the 2021 reporting year was 626, 329 yellow-finned bream and 297 pikey bream. Pikey bream tended to dominate in the northern sites while yellow-finned bream tended to dominate in the southern sites.

Mud Crabs Results

Auckland Inlet is a tidal inlet that connects to the Inner Harbour through a complex network of small streams meandering through mangrove-lined mudflats that are often inundated at high tide.

Only two mud crabs were caught in Auckland Creek over the two sampling rounds. As such the overall score, sex ratio and prevalence of rust lesions could not be calculated owing to the insufficient sample size. Abundance was scored as very poor (0.00). To note, less than five crabs were caught in this zone over the two sampling periods for the fourth consecutive year.