ENVIRONMENTAL
RESULTS
ABOUT THE ZONE
Boat Creek is a small mangrove-lined estuary connected to the western side of the Western Basin.
WATER & SEDIMENT
Boat Creek received an overall water quality score of 0.71 (B).
Sediment quality of Boat Creek was very good with an overall score of 0.91 (A).
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The following graphs compare the Water and Sediment scores reported for 2025 (top line) to those from 2024.
WATER
SEDIMENT
Very good (0.85-1.00)
Poor (0.25-0.49)
Good (0.65-0.84)
Satisfactory (0.5-0.64)
Very Poor (0.00-0.24)
No data available
Overall, Water quality in Boat Creek scored 0.71 and received a Good (B) grade, similar to the 2024 Report Card. This score was calculated by aggregating the three sub-indicator and associated measure scores (Physicochemical – pH and turbidity, Nutrients – total nitrogen, total phosphorus and chlorophyll-a, and dissolved metals – aluminium, copper, lead, manganese, nickel and zinc).
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Boat Creek received a Very Good (A) grade for pH (1.00) and a Good (B) grade chlorophyll-a (0.65). All of the six of the dissolved metals received a Very Good (A) grade, indicating that average concentrations for these measures were within the guideline values for this zone. Turbidity (0.38), total nitrogen (0.35), and total phosphorus (0.33) all received a Poor (D) grade.
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For Sediment quality, Boat Creek received an overall score of 0.91 and a Very Good grade (A), a similar result to the previous year. This score was calculated by aggregating one sub-indicator and associated measure scores (Metal and metalloids – arsenic, cadmium, copper, lead, mercury, nickel and zinc). The results reflect that all concentrations were below the guideline values for this zone. Arsenic (0.80, Good, B) and nickel (0.57, Satisfactory, C) are naturally occurring within the harbour and may not be associated with anthropogenic inputs.
HABITATS
MANGROVE RESULTS
The 2025 Gladstone Harbour Report Card incorporates the 2024 Mangroves results. Mangrove condition has historically remained stable due to strong buffering capacity, and since 2019, monitoring has been undertaken every five years. In 2024, the overall grade for Mangroves at Boat Creek improved two grades from Poor (D) in 2019 to Good (B).
The mangrove extent sub-indicator, which measures changes in canopy cover relative to saltmarsh and saltpan areas, improved to a Satisfactory (C) grade. The canopy condition indicator, based on remote sensing of canopy density and health, improved from Poor (D) to Good (B). Shoreline condition, assessed through aerial surveys of mangroves bordering Gladstone Harbour’s water quality zones, also improved, to a Satisfactory (C) in 2024.
FISH & CRABS
FISH RECRUITMENT RESULTS
Fish recruitment was assessed for two species: Yellowfin bream Acanthopagrus australis and Pikey bream A. pacificus. The overall score for 2025 was higher than the previous year (2024: 0.62, 2025; 0.77) and improved from a Satisfactory (C) to a Good (B) grade. This is a result of increased catch numbers for Pikey beam (2024: 1, 2025: 6), though Yellowfin bream declined (2024: 4, 2025: 1).
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The Fish recruitment grade for Boat Creek improved in 2025 (0.77) from 2024 (0.62), resulting in an increase to a Good (B) grade from a Satisfactory (C) in 2024.
MUD CRAB RESULTS
The overall zone score for Mud crabs for Boat Creek was 0.74 and graded Good (A), similar to 2024 (0.75, Good, B). At the sub-indicator level, abundance remained at a Very Good (A), reflecting a high catch rate. Mud crab populations may be influenced by both human activities and natural factors, including habitat, reproductive cycles, and environmental conditions like temperature and water movement.
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In Queensland, it is illegal to take female crabs, hence changes in the ratio of male to female crabs can indicate changes in fishing pressures. Sex ratio for Boat Creek declined from a Poor (D) in 2024 to a Very Poor (E) grade in 2025, indicating an imbalance of males and females. The prevalence of rust lesions retained a Very Good (A) grade and indicates a very low number of crabs with rust lesions.