WHAT WE MEASURE
AND WHY
Select an indicator from the list below to learn more about how and why it is measured.
Water & Sediment
Fish Recruitment
Sense of Place
Seagrass
Mud Crabs
Indigenous Cultural Heritage
Coral
Harbour Usability
Economic Performance
Mangrove
Harbour Access
Economic Stimulus
Fish Health
Liveability/
Wellbeing
Economic Value (Recreation)
WATER AND SEDIMENT
Water quality is assessed through three sub-indicators — Physicochemical, Nutrients and Dissolved metals — which were comprised of eleven measures.
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Physicochemical: pH and turbidity
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Nutrients: total nitrogen, total phosphorus and chlorophyll-a
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Dissolved metals: aluminium, copper, lead, manganese, nickel and zinc
One sub-indicator was used to assess sediment quality — Metals and metalloid — and is comprised of seven measures.
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Metals and metalloid: arsenic, cadmium, copper, lead, mercury, nickel and zinc
Please refer to the 2023 GHHP Technical Report for more information on the measures listed above.
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WHY WAS IT MEASURED?
Water and sediment quality are important and interconnected aspects of the harbour ecosystem. Healthy water and sediment are necessary to sustain a variety of marine life. Many environmental and human-related factors play a role in determining the water and sediment quality of the harbour.
The Gladstone Harbour Report Card uses standard measures for Water and Sediment Quality that were recommended by the Independent Science Panel. All eighteen Water and Sediment Quality measures have local or national guidelines. Data used to determine water and sediment quality scores and grades for the 2023 report card were provided by the Port Curtis Integrated Monitoring Program. Water quality data is collected quarterly from 51 sites across 13 harbour zones. Sediment quality data is collected annually from the same sites.
SEAGRASS
Seagrass meadows in Gladstone Harbour are located in The Narrows, Western Basin, Inner Harbour, Mid Harbour, South Trees Inlet and Rodds Bay. Three sub-indicators of Seagrass health were measured to calculate the seagrass score for the Gladstone Harbour Report Card:
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Biomass: Average above-ground biomass within a monitoring meadow.
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Area: Total area of a monitoring meadow.
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Species composition: Relative proportions of different seagrass species within a monitoring meadow. Meadows with a higher proportion of historically dominant species receive higher scores.
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Meadow condition is defined as the lowest sub-indicator score when this score is either meadow area or biomass. Where species composition is the lowest score, the overall meadow score is 50% of the species composition score and 50% of the next lowest score (area or biomass).
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The zone grade was measured as the average grade of the meadows within that zone.
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WHY WAS IT MEASURED?
Seagrass meadows are one of Gladstone Harbour’s most important habitat types. There are 14 seagrass meadows monitored in six harbour zones within the GHHP reporting area. The area and distribution of seagrass meadows can vary on an annual basis and at peak distribution seagrass meadows in Gladstone Harbour can cover an area of approximately 12,000 ha. The seagrass meadows provide a range of important ecosystem functions such as sediment stabilisation, nutrient cycling and carbon sequestration. They also provide nursery areas for juvenile fishes and foraging areas for dugongs, turtles and large fish such as barramundi.
Seagrass meadows have been monitored in Gladstone Harbour since 2002. Nearly two decades of monitoring and research has provided insight into potential causes and trends regarding changes in the seagrass meadows of Gladstone Harbour. GHHP acknowledge and thank Gladstone Ports Corporation for its contribution of data, images and information provided from their annual seagrass monitoring program.
CORAL
Coral communities are iconic components of marine ecosystems in Australia. They provide spawning, nursery and feeding areas a variety of marine animals. Corals also provide important ecosystem services such as nutrient recycling and carbon fixation. In addition to their ecological value, coral reefs have considerable social and economic importance.
The Coral indicator consists of four sub-indicators: Coral cover, Macroalgal cover, Juvenile density and Change in hard coral cover. Coral in Gladstone Harbour have been monitored since 2015.
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WHY WAS IT MEASURED?
Coral cover
High coral cover suggests that a large breeding population is available, which increases its recovery potential and that of neighbouring reefs. High coral cover also contributes to a reef’s structural complexity and biodiversity by providing habitat for fishes and other marine creatures. This sub-indicator is used predominantly to inform on the state of a reef.
Macroalgal cover
Macroalgae include large fleshy species of red algae, brown algae and green algae. When abundant, macroalgae occupies space otherwise available for corals and shades the corals, thus inhibiting coral recruitment and growth. As macroalgae have a negative impact on coral, high macroalgal cover is indicative of poor coral reef condition and low macroalgal cover is indicative of good condition.
Juvenile coral density
Recovery of coral reefs from disturbances such as flooding, cyclones, bleaching or outbreaks of crown-of-thorns starfish is dependent on the recruitment of new coral colonies. Higher juvenile density indicates greater coral recruitment levels. Hence juvenile coral density can provide an indication of a reef’s recovery potential.
Change in hard coral cover
Hard coral cover change is assessed by measuring the rate at which hard coral cover increases and provides a direct measure of recovery potential. This sub-indicator captures the coral growth rate by comparing the observed rate of change (where there is no acute disturbance) to the rate of change observed from other nearshore reefs.
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MANGROVES
Three indicators—mangrove extent, canopy condition and shoreline condition are used to assess mangrove health.
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Mangrove extent
Tidal wetlands often occupy soft sediment tidal slopes between mean sea level and highest tide level. These wetlands consist of mangroves, salt marsh and salt pans with the relative proportion of wetland occupied by each group being influenced by climate, particularly rainfall and sea level. For example, a reduction in rainfall can lead to a reduction in the area of wetland occupied by mangroves.
Report card scores for this indicator are based on satellite imagery from which the proportions of mangroves and salt marsh/salt pans is determined. A net gain in the proportion of a wetland occupied by mangroves will result in a good score and a loss of mangrove area results in a poorer score.
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Mangrove canopy condition
Mangrove canopy density, measured across a forest, provides an indication of current mangrove health. Healthy forests typically have a dense canopy cover. However local or regional impacts such as changes in long-term rainfall or sea level, localised herbivory, altered hydrological regimes, increased sediment, and nutrient loads and localised pollution events can result in a decline in canopy density.
Report card scores for this indicator are derived from satellite imagery. A high score indicates a dense canopy in good condition while a low score indicates a sparse canopy in poor condition.
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Shoreline condition
Shoreline mangroves can respond rapidly to changes in water quality, climate, and tidal conditions. They provide a valuable indicator of mangrove health.
Shoreline condition was assessed using aerial photographs of the shoreline taken from a helicopter. At each 50 m interval of the shoreline the presence or absence of dead mangroves was noted. Those zones with a significantly higher number of dead mangroves received a poor score and those with a significantly lower number of dead mangroves received a good score.
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WHY WAS IT MEASURED?
Mangroves are coastal ecosystems consisting of flowering trees and shrubs adapted to marine and estuarine conditions. Exposed breathing roots, salt-excreting leaves and live water-dispersed propagules help mangroves to cope with tidal inundation and salt saturated, oxygen poor soils.
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Mangroves provide valuable habitat for important aquatic species like barramundi, mud crab, and prawns. The canopy provides numerous niches for bird species, roost sites for flying foxes and feeding areas for small mammals. Mangroves provide vital ecosystem services. Coastal mangroves protect seagrass and coral communities by filtering catchment runoff and limiting shoreline erosion by reducing wave energy. Mangroves are highly productive and have a high capacity for carbon storage.
Owing to their environmental importance mangroves are protected in Queensland under the Queensland Fisheries Act 1994.
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As variation in mangrove scores is likely to be small from year to year in response to changes to climatic conditions such as wet or dry years and/or changes in sea level. Mangrove monitoring will move to a 5-year cycle with the next scheduled mangrove monitoring to occur in 2024. The results form monitoring conducted in 2020 will be used to calculate the overall Environmental score in 2021 and in subsequent report cards until the next round of monitoring.
FISH HEALTH
The Fish health grades and scores are generated from two separate monitoring projects:
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Fish condition: An automated visual assessment is made from images captured by fishers using a mobile app. Length and weight data are also recorded at the time of capture.
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Fish Health Assessment Index (HAI): A thorough assessment of the health of individual fish based on visual condition and the condition of several organs and tissues.
Data for Fish condition was collected by fishers at the Australian Bass Tournament, members of the Gladstone Sports Fishing Club, members of the public reporting recaptures of tagged fish and Infofish Australia. Based on machine learning algorithms the Trackmyfish app assesses a photo of individual fish for five indicators of visual health.
Scores for Fish condition were determined for five fish species; Yellowfin bream, Pikey bream, Barred javelin, Dusky flathead and Mangrove jack and are based on two separate metrics 1) visual fish condition: a visual assessment of fish health which includes skin, eyes, fins parasites and deformities and 2) fish body condition: calculated from length and weight data recorded at the time of capture. Measures of body condition are widely used to assess the health of individual or groups of fish. Generally, fish that are heavier than average for their length are considered healthier with more energy reserves for normal activities.
Survey work for the Fish HAI was conducted across Gladstone Harbour using gill nets. Fish were photographed, measured and examined for abnormalities, parasites, lesions or erosion. While most fish were released alive at the point of capture up to 25 of each of the target species were retained for laboratory analysis.
The Fish HAI was calculated from scoring and summing visual inspection scores for the following external and internal measures, skin, eyes, fins, gills spleen, kidney, hindgut, liver and parasite load. A harbour wide Fish HAI was determined for five fish species or groups: Barramundi, Breams, Barred javelin, Blue catfish and Mullet.
Owing to fish movements, the overall score for Fish health is calculated at the harbour level. The single harbour score is necessary as fish are mobile and the health of the monitored species can not necessarily be attributed to individual monitoring zones. However, except for barramundi which move large distances, the range of movements in the remaining target species are suitable for the assessment of Gladstone Harbour as a whole.
Fish have been examined from the north, central and southern harbour areas. This provides a good spatial coverage that includes developed and undeveloped areas of the harbour. As the location of each fish captured is recorded, it will be possible to identify any fish health ‘hot spots’ using this approach.
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WHY WAS IT MEASURED?
Fish are one of the most important social, economic and ecological resource in Gladstone Harbour. As a result, they were identified as a major concern at community workshops conducted by GHHP in 2013 to develop a community vison for the Gladstone Harbour Report Card.
Recreational fishing in Gladstone occurs throughout the harbour and is both boat and shore based. Fishing, particularly for barramundi also occurs in nearby Lake Awoonga which is regularly stocked by Gladstone Area Water Board. In 2019, the value of recreational fishing in Gladstone was estimated at nearly 27 million dollars. Commercial fishing in Gladstone includes net, pot, line and trawl fishing.
Fish play a multitude of roles in aquatic ecosystems including nutrient cycling, ecosystem regulation and bioturbations. Fish are important in nutrient cycling as they store a large proportion of ecosystem nutrients like phosphorus and nitrogen in their tissue and they transport nutrients further than other aquatic animals. The nutrients they excrete are readily available to primary producers such as algae or seagrass.
FISH RECRUITMENT
Counts of two juvenile bream species were recorded monthly at 26 sites across 12 harbour zones between December and February. Fish with a tail-fork length of 100 mm or less were classified as juvenile.
To determine Fish recruitment grades and scores, a statistical model was developed that relates previous results to the annual catch rate per trip and per site and incorporates seasonal and other relevant environmental variables. The recruitment indicator scores are determined from this model, which is updated on an annual basis.
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WHY WAS IT MEASURED?
The Fish recruitment indicator is based on the total catch of juveniles of two bream species (Yellowfin and Pikey bream).
Fish recruitment is defined as the number of juvenile fish entering the mature fish population each year. Fish recruitment is one of the key dynamic functions that affects fish populations.
MUD CRABS
Three sub-indicators were selected for the report card: abundance, sex ratio and prevalence of rust lesions.
Abundance
Abundance is used to estimate the number of mud crabs within a given area. This sub-indicator is indirectly measured as catch per unit effort (CPUE), which is the total catch divided by the number of crab pots. Changes in abundance may indicate changes in fishing pressure, habitats or recruitment levels. However, CPUE data can be highly variable. Catch may be impacted by capture technique, sampling area and time, or owing to differences in crab distribution, growth or survival.
Sex ratio
The sex ratio sub-indicator assesses the ratio of legal-size male crabs (>15 cm spine width) to female crabs of the same size. In Queensland mud crab fisheries, it is illegal to take female crabs. Therefore, changes in the ratio of male to female crabs may indicate changes in fishing pressures. This can alter population dynamics and may cause changes in ecosystem processes, as only male crabs dig burrows and female crabs often migrate offshore to spawn.
Prevalence of rust lesions
Rust spots (shell lesions) were first reported in Gladstone Harbour by commercial fishers in 1994. The disease is not infectious; it has been suggested that it may be related to exposure to copper and zinc, which inhibit calcium uptake. However, this relationship has not been demonstrated experimentally. The prevalence of rust spot is calculated by comparing the number of crabs with rust lesions to the total number of mud crabs caught at each monitoring zone.
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WHY WAS IT MEASURED?
Mud crabs are one of Gladstone Harbour’s iconic species. Their health was identified as a major community concern at workshops conducted by GHHP in 2013 due to their value to commercial and recreational fishers and the reported high rates of rust spot disease. Mud crabs spend most of their adult lives in burrows in estuarine mangrove habitats. Their abundance, size distribution and health are related to environmental conditions and fishing pressures within these habitats. This is the seventh year that mud crab indicators have been included in the report card.
HARBOUR USABILITY
The three Social Health indicators were assessed through a Computer-Assisted Telephone Interview survey and an online version of the same survey in 2022, with a total of 200 participants.
The Harbour Usability indicator group comprised three indicators: (1) Satisfaction with harbour recreational activities, (2) Perceptions of air and water quality in the harbour area and (3) Perceptions of harbour safety for human use.
The marine safety incidents and oil spills measures were assessed through secondary data sourced from Maritime Safety Queensland, Department of Transport and Main Roads.
HARBOUR ACCESS
The three Social Health indicators were assessed through a Computer-Assisted Telephone Interview survey and an online version of the same survey in 2022, with a total of 200 participants.
The Harbour access indicator group comprised four indicators: (1) satisfaction with access to the harbour, (2) satisfaction with boat ramps and public spaces, (3) perceptions of harbour health and (4) perceptions of barriers to access.
LIVEABILITY / WELLBEING
The three Social Health indicators were assessed through a Computer-Assisted Telephone Interview survey and an online version of the same survey in 2022, with a total of 200 participants.
Liveability refers to the elements in a region that affect how individuals feel about living there. Those elements include the physical environment (natural and human) and social elements such as feelings of community spirit, wellbeing, culture and opportunities for work and recreation. The Liveability and Wellbeing survey questions related to whether Gladstone Harbour makes living in Gladstone a better experience and the level of participation in community events.
SENSE OF PLACE
The Sense of Place indicator group comprised six indicators:
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Place attachment: the degree to which the harbour provides an identity that is unique or distinct from other identities.
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Continuity: adds a temporal aspect to Sense of Place. It relates to the extent to which there has been continuity of ‘self’ (including ancestors) and activities in a place.
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Pride in the region: reflects people’s values, standards, and assesses pride in one’s identity in relation to place.
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Well-being: relates to the extent to which a place facilitates or enables one’s chosen lifestyle, or conversely, the extent to which a place does not hinder one’s social and economic opportunities. This indicator assesses people’s sense of ‘feeling at home’ and the extent to which this provides spiritual fulfilment or has restorative capacity.
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Appreciation of the harbour: assesses the attitudes of people in Gladstone with particular emphasis on its importance as a great asset to the local community and Central Queensland.
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Values: assesses community values on marine life, recreational and tourism activities, and the cultural, spiritual and historical significance of the harbour.
INDIGENOUS CULTURAL HERITAGE
The overall grade for Indigenous Cultural Heritage is based on the Physical condition and Management strategies of monitored cultural sites. The scoring structure takes into consideration the social, spiritual and scientific values of the sites and any anthropogenic or natural impacts.
Indigenous Cultural Heritage was assessed in 2019 through field surveys undertaken in four zones, The Narrows, Facing Island, Gladstone Central, and Wild Cattle Creek. Within each zone, a reference site (cultural locus site) was identified, against which the other sites were assessed. The cultural health of sites was weighted using inputs from the Traditional Owners and Elders.
Physical condition is assessed by three measures:
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Intactness of site features: Relates to heritage features within site being undisturbed and artefacts are in situ. A score of 10 is allocated when over 90% percent of the features are intact.
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Extent of current disturbance: Relates to the percentage of site currently being disturbed by human and natural processes such as vehicle damage, erosion processes, animal or trampling impacts, dumping rubbish and camping. A site attracts a score of 10 if less than 10% of a site is subjected to current or active disturbances.
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Management of threats: Based on a threats assessment for the site and identifying any management strategies are in place to minimize the impacts or threats to the site. When a site has management strategies in place to tilizat over 90% of threats it receives a score of 10.
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The Management strategies indicator uses six measures:
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Recording: Examines whether sites have been further researched and investigated during monitoring. A score of 10 is given when all sites were revisited in the zone and new monitoring stations were established.
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Cultural management: Relates to the preparation and implementation of a cultural heritage management plan. A zone would receive a score of 10 if a heritage management plan is implemented for the zone and all management activities are in progress.
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Stakeholders: Relates to the engagement of various stakeholders towards a long-term management plan for the zone. A score of 10 reflects representatives from all stakeholders’ groups are actively engaged and support ongoing activities.
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Monitoring: Relates to the annual monitoring of each site each year. A score of 10 is given when all existing monitoring stations have been revisited.
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Access: Relates to the percentage of sites within a zone that can be easily accessed for heritage management. A score of 10 is allocated for this measure when all sites within the zone are easily accessible for heritage management activities.
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Cultural resources: Relates to the availability of both physical and digital resources that store knowledge of cultural heritage within a zone. A score of 10 reflects that all sites within a zone have both physical and digital interpretive resources.
ECONOMIC PERFORMANCE
The economic performance indicator group consisted of three indicators based on key industries using the harbour, shipping, tourism and commercial fishing.
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Shipping
Data on monthly shipping movements were provided by the Gladstone Ports Corporation. The score for shipping activity was based on a capacity tilization (current level of activity relative to potential level of activity) estimate. To determine the score, data for the 2022–23 financial year were compared to a 10-year baseline dataset from 2013–14 to 2022–23.
Tourism
The score for Tourism was based on expenditure on hotel accommodation, food and other local services relative to a 10-year average from 2009-10 to 2018–19 in the Gladstone region. Since 2017 the tourism indicator has been supplemented by expenditure made by passengers and crew members of cruise ships docked in Gladstone Harbour.
Commercial Fishing
The score for Commercial fishing was based on fishing effort and the value of the landed catch in three fishery sectors: the net (fish), pot (mud crab) and otter trawl (prawns) relative to a 10-year average starting from 2012–13. The line fishing measure was excluded from 2018 owing to considerable data gaps over the past 10 years and the very small size of this fishery. Fishing production data collected from the Gladstone area (Grid S30) was used as the primary data source for the commercial fishing indicator.
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The total value of Commercial fishing was estimated based on catch data by fishing method derived from the QFish database and the average prices for each species group (fish, prawns and crabs) derived from the most recent Australian fisheries and aquaculture statistics report. The three fisheries sector scores were weighted by their relative contribution to Gross Value Production.
ECONOMIC STIMULUS
The economic stimulus indicator group consisted of two indicators: employment and socio-economic status.
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Employment
The score for Employment measures the unemployment rate for the Gladstone Local Government Area compared to unemployment rates in all Queensland Local Government Areas. This comparison used the most recent Australian Bureau of Statistics data available, which were for the 2021 December quarter.
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Socio-economic status
The score for Socio-economic status was derived using the Index of Economic Resources (IER). The IER was calculated using Australian census data and refined using data from a Computer-Assisted Telephone Interview survey of 200 Gladstone residents conducted in June 2022.
ECONOMIC VALUE (RECREATION)
The Economic Value (recreation) indicator group was assessed through four indicators, land-based recreation, recreational fishing, beach recreation and water-based recreation (non-fishing). The score for this indicator is based on the mean satisfaction rating by those who undertook the activity and the economic value of the recreational trips.
Information on the non-market economic value (recreation) of harbour area activities was collected through a community survey of 200 people within the Gladstone region via a Computer-Assisted Telephone Interview survey. Data on travel costs, travel time, and other access and site costs were used to calculate the economic value of using a recreational site based on the investment that people have made in the activity. In 2014, the economic value of land-based ($61 per trip) and beach-based recreational trips ($40 per trip) were estimated. Additional information was collected in 2018 to estimate the value of a recreational fishing trip ($141) and water-based recreation ($95).
