Australia’s marine industries encompass a range of activities that add significant economic value and employ many Australians across several sectors (AIMS 2021a) (see case study: The blue economy). Here, we consider pressures associated with commercial fisheries; shipping; extraction and production of minerals, oil and gas; renewable energy generation; and the anthropogenic noise associated with these activities. Aquaculture is currently almost entirely restricted to bays and estuaries (although offshore aquaculture is expected to expand rapidly in coming years) and thus is considered in the Coasts chapter (see the Coasts chapter). A sustainable ocean economy must be built on diverse relationships, in ways that encourage equity and inclusion, and recognise the nonmaterial aspects of wellbeing (Allison et al. 2020). For example, marine industries such as offshore energy and sustainable aquaculture should be developed in a manner that improves community prosperity and wellbeing, while also promoting thriving marine ecosystems (Future Earth Australia 2021). In Australia, literature is lacking on the views and perspectives of Traditional Owners about their specific opportunities and challenges with the blue economy. Significant challenges for Traditional Owners within the blue economy are poor inclusion in processes; lack of Traditional Owner rights; and the missed benefits associated with exclusion, under-resourced participation, and lack of mentoring or advancement through western education systems and scholarship opportunities. Including Indigenous voices more systematically in processes of negotiation and agreement making with industry will benefit Indigenous communities, as well as supporting industry with its goal of good corporate citizenship. Assessment Pressures on the environment associated with industry 2021 Adequate confidence Indigenous assessment Pressures on the Australian marine environment arising from consumptive and extractive use are generally low impact and improving. The exception is recreational fishing, which is considered to have high impact, but is also improving. Traditional Owners view commercial fishing and recreational fishing as high-impact activities that continue to impact sea Country. Pressures arising from nonconsumptive/non-extractive uses of the Australian marine environment are generally low impact, but the trend is unclear or (in the case of shipping) deteriorating. Traditional Owners see nonconsumptive/non-extractive use of sea Country as very low impact, except for shipping, which is identified as high impact. Note that the spatial scale of Indigenous and western science assessments may be different. Related to United Nations Sustainable Development Goal targets 12.2, 14.2, 14.4, 14.6 Legend How was this assessment made Share on Twitter Share on Facebook Share on Linkedin Share this link Assessment Commercial fishing 2021 Adequate confidence 2016 2011 Many pressures have been reduced through management, but some still exist for a number of target and bycatch species (Pitcher et al. 2021). The Indigenous assessment regionally was high impact, with a deteriorating trend. Assessment Indigenous commercial fishing 2021 Limited confidence Commercial fishers are not required to indicate their Indigenous status; therefore, drawing out state and trend information for Indigenous commercial fishers is not currently possible (Fischer & Hunter 2021a). Assessment Shipping (marine vessel activity) 2021 Limited confidence 2016 2011 Most impacts are localised. A continued increasing trend of the pressure is reflected in a trend of ‘deteriorating’; however, realised impacts may be mitigated by strong management (Peel & Smith 2021). The Indigenous assessment regionally was high impact, with a stable trend. Assessment Mineral, oil and gas extraction and production 2021 Adequate confidence 2016 2011 Mineral mining activities remain stable; oil and gas exploration activities have decreased; oil production activities have decreased; and gas production activities have increased (Evans et al. 2021b). The Indigenous assessment locally was low impact, with a stable trend. Assessment Offshore renewable energy generation 2021 Limited confidence 2016 Few data are available on environmental pressures of marine renewable energy generation. Pressures are undetectable at the current scale, with no indication of increase (Hemer 2021b). The Indigenous assessment locally was very low impact, with an unclear trend. Assessment Anthropogenic marine noise 2021 Limited confidence 2016 Noise generated by shipping is present around much of Australia. Oil and gas activities are associated with the main exploration and extraction regions (north-west and south-east), and port and coastal activities are largely associated with urban areas. Monitoring and quantification of inputs are lacking (Evans et al. 2021e). The Indigenous assessment locally was very low impact, with a stable trend. Case Study The blue economy The ‘blue economy’ is an increasingly accepted term for ocean-based industries that maintain environmental and social stewardship and protection (UNEP 2016, Voyer et al. 2018). Economic scale of Australia’s blue economy As of 2017–18, Australia’s marine industries contributed approximately $81.2 billion to the Australian economy (around 3.7% of Australia’s gross domestic product – GDP), having grown from $63.6 billion in 2015–16 (AIMS 2018, AIMS 2021a); Figure 19) This is similar in magnitude to Australia’s agricultural production or coalmining, and is estimated to be growing at 2–3 times the rate of the rest of Australia’s GDP. Associated employment was estimated to be around 393,000 full-time workers. Although this growth may have been slowed by the COVID-19 pandemic and trade fluctuations with China, growth is still forecast over the next few years (Mobsby et al. 2020), and the total contribution of Australia’s blue economy is expected to exceed $100 billion by 2025 (NMSC 2015). Figure 19 Total income from various marine activities that contribute to the blue economy, 2017–18 Expand View Figure 19 Total income from various marine activities that contribute to the blue economy, 2017–18 Source: AIMS (2021a) Download Go to data.gov Broader value and state of the blue economy Environmental status, social values and equity are important aspects of the blue economy. A fair degree of inequity exists in the beneficial returns from offshore activities. Much of the development is industrial in scale, and benefits are dispersed to shareholders. Growing ocean literacy and sea Country claims may see this imbalance addressed in the future. Direct human pressures on marine ecosystems and habitats, along with climate change and ocean acidification, are reshaping Australia’s oceans. Fisheries have put considerable effort into transitioning all Australian stocks to a sustainable status, but other aspects of the marine environment, such as food-web structure, have shifted, with unknown effects on longer-term sustainability in many cases. Expansion of marine infrastructure could contribute to ongoing pressures and declining environmental trends. However, clever design could help offset losses (e.g. to biodiversity) by providing a network of additional habitat areas. Evolving seascape of blue economy sectors Traditionally strong sectors within the blue economy, such as fisheries, have remained relatively stable in recent years, at around $1.79 billion in 2018–19 (Patterson et al. 2020), despite facing many challenges due to climate stressors. Aquaculture continues to grow, reaching $1.4 billion in 2018–19, a 26% increase within a decade (Steven et al. 2020). Although oil and gas production remains the dominant energy sector within Australia’s blue economy (AIMS 2018), it has declined significantly in recent years. Even before the COVID-19 pandemic began in 2020 (causing a jobs decline of 25% in 2020), Australian oil and gas jobs in 2019 had experienced a downturn of nearly 24% from 2014 levels (Wood Mackenzie 2020). As part of energy transitions, offshore renewable energy is now in an exploratory phase – the Star of the South offshore wind project (Star of the South 2020) has been granted an exploration licence, and several other proposals are in development. If the potential of the Star of the South development is fully realised, it could supply up to 20% of Victoria’s electricity needs and support 200–2,000 new jobs (more during the construction phase than the operational phase). The potential integration or co-location of different offshore energy activities (e.g. wind, wave, tidal, solar) and seafood production activities (i.e. aquaculture) could further add to the prosperity of these projects. This would ultimately add to Australia’s contributions to global trade markets (Aryai et al. 2021). A 2020 commitment by the Australian Government to develop a Commonwealth offshore clean energy regulatory framework seeks to support future projects and growth in the sector (e.g. hydrogen production). Outlook Management of marine and coastal activities comes under several agencies across several jurisdictions, resulting in a complicated and complex space for operations. This complexity could undermine desirable outcomes, particularly with regard to pressures, such as climate change, that do not respect jurisdictional boundaries. National approaches to marine and coastal issues – such as the relevant sections of the Environment Protection and Biodiversity Conservation Act 1999 or the National cooperative approach to integrated coastal zone management (DEH & NRMMC 2006) – have had varying levels of success, depending on cooperation across jurisdictions and agencies. Without continuing cooperation, environmental degradation is a significant risk, because consideration of single industries or pressures fragmented over multiple jurisdictions will likely be overwhelmed by the combination of climate change and expanding uses of the environment. This siloed approach also jeopardises the management of vast stores of data related to Australia’s blue economy, which are largely sporadic and unconnected across governments, research agencies and industry (despite some notable advances through the Integrated Marine Observing System Australian Ocean Data Network in recent years). Disclosure and improved accessibility of data can incentivise innovation, new public–private instruments for investment, and creation of new business models (Northrop et al. 2020). If integrated approaches (see case study: Baselines, monitoring and integrated ecosystem assessments), and cooperation at the jurisdictional, agency and public–private levels is achieved, the blue economy can live up to its vision of prosperity and sustainability. Share on Twitter Share on Facebook Share on Linkedin Share this link Commercial fishing Australia’s wild-caught marine fisheries are highly diverse and economically significant, contributing $1.79 billion to the economy in 2017–18 (Patterson et al. 2020; Figures 19 and 20). These fisheries catch scallops, prawns, crabs, squid, rock lobster, abalone, coastal fish such as whiting and flathead, reef fish such as coral trout, shelf and deepwater fish such as ling and blue-eye trevalla, and oceanic tuna and billfish, using methods ranging from small-scale netting to large-scale pelagic longline fishing and trawling (FRDC 2021b, Pitcher et al. 2021). Pressures caused by commercial fishing The pressures caused by commercial fishing depend on the level of fishing effort. Although fisheries operate across all Australian waters, fishing effort is not evenly distributed. The greatest fishing effort occurs in the Temperate East, South-east, North and South-west marine regions (with effort greatest in the Temperate East and South-east). The impact of fisheries on the marine environment depends on the equipment used, and species and habitats in the area. As well as causing impacts on targeted species, commercial fishing affects bycatch species (including byproduct and discarded/released species) and sometimes habitats, where fishing gear interacts with the sea floor or benthic habitats (e.g. demersal trawling). Bycatch species mostly consist of other fish or invertebrate species, but can also include protected or migratory species such as sygnathids (e.g. seahorses), sea snakes, marine turtles, seabirds and marine mammals. Matters of national environmental significance (MNES) are potentially impacted through fishing, as there are overlaps between all Australian fisheries and the currently identified MNES. Some of these (e.g. demersal sharks) are very highly impacted. Assessing changes in commercial fishing The Status of Australian fish stocks reports assess 120 species, made up of 406 stocks, across state, territory and Commonwealth jurisdictions (FRDC 2021b). In 2018, 324 of the 406 stocks were assessed (Figure 20). Of these, 254 were classified as sustainable, 18 as recovering, 23 as depleting and 29 as depleted. The remainder were classified as undefined. Of depleted and depleting stocks, several have recovery management plans in place that aim to rebuild the stocks. The number of stocks assessed increased from 150 in 2012 to 406 in 2020, of which 84% were not subject to overfishing and 86% were not overfished. Since July 2018, the Status of Australian fish stocks reports have also been used to inform progress against United Nations Sustainable Development Goal target 14.4.1. Various jurisdictions also evaluate and report on the status of fisheries they manage. There has been a decrease in the number of depleted stocks in some jurisdictions and an increase in the number of stocks assessed or explicitly managed (FRDC 2021b). In the past 5 years, fishing efforts have decreased in all trawl fisheries in all marine regions, which has reduced trawl footprints over the past 1–3 decades. The most extensive trawl footprints have occurred in the Temperate East, South-east, North and North-west marine regions (Pitcher et al. 2018), associated with the Queensland East Coast Prawn Trawl, South East Trawl (Commonwealth), Northern Prawn (Commonwealth), New South Wales Ocean Trawl, and Western Australia Trawl fisheries. Figure 20 Australian fisheries and aquaculture production value, 1999–2000 to 2024–25 (projected) Expand View Figure 20 Australian fisheries and aquaculture production value, 1999–2000 to 2024–25 (projected) Source: ABARES (2021) Download Go to data.gov Share on Twitter Share on Facebook Share on Linkedin Share this link Total bycatch has been estimated for some fisheries and jurisdictions (e.g. Kangas et al. 2007, Tuck et al. 2013, Wang et al. 2019), but there has been no national assessment. A framework for assessing the ecological impacts of fishing has been developed and applied to several Australian fisheries to assess the risks to the many nontarget species taken in Commonwealth fisheries (Hobday et al. 2011). Similarly, habitat assessments have been completed for a small number of fisheries, but these have been mostly semi-quantitative. There has been no national analysis of the cumulative impacts of all commercial fishing on marine habitats. Indigenous commercial fishing Indigenous people participate in commercial fisheries for diverse purposes, including economic, social, cultural and environmental. Indigenous commercial fisheries are often interchangeable with cultural fisheries or traditional Indigenous fisheries (Fischer & Hunter 2021a). Indigenous fishing is not considered a ‘pressure’ on the environment within an Indigenous worldview. Indigenous fisheries were a component of the Australian ecosystem before western fisheries management arrangements. Cultural fisheries can offer the discourse and branding of Indigenous wild-catch industry based upon ancient traditions (Lee 2019b). However, cultural commercial fisheries are not dependent on how ‘cultural’ an activity is; rather, they recognise the identity and variety of experiences that Indigenous fishers bring to their commercial activities (Smyth et al. 2018) (see the Indigenous chapter). Indigenous leaders and communities work continually to build the supportive policies and strategies that remove unintended consequences of restricting economic development for Indigenous fishers. All commercial fishers, including Indigenous commercial fishers, record their catches in commercial logbooks. However, as commercial fishers are not required to identify as Indigenous (with few exceptions), data on Indigenous catch may not be comprehensive. There is also a lack of specific data relating to Indigenous engagement in the commercial sector, and different and competing jurisdictional definitions of Indigenous commercial fishing operations. Research in New South Wales found that approximately 3% of fishing businesses in 2011 were Indigenous owned (Schnierer & Egan 2012). By 2021, that number had declined to approximately 2% (NSW DPI 2019). A lack of data hinders a national approach to policy, management, education, and research (see Indigenous commercial fishing). Marine vessel activity As an island, Australia relies heavily on shipping for transportation of its domestic freight, and international imports and exports (Peel & Smith 2021). As well as commercial vessels, many smaller vessels use Australian waters and provide an important recreational pastime for many Australians. Pressures caused by marine vessel activity Marine vessels can cause adverse interactions with the marine environment across all regions of Australia (AMSA 2014, Erbe et al. 2019; Figure 21). These interactions include environmental damage from collision or grounding of vessels, chemical pollution from fuel spills, biofouling, exhaust (see the Air Quality chapter), noise pollution (see Anthropogenic marine noise), invasive species from ballast water (see the Coasts chapter), sea bottom damage from anchorage, and direct collision with marine fauna (e.g. whales, turtles, dugongs; see Marine biodiversity protection). There is also emerging evidence that marine antifouling coatings may be an important source of microplastic pollution (Dibke et al. 2021). Figure 21 Shipping (>24 metres) density in kilometres travelled (per 1/30 degree grid cell) for the Australian exclusive economic zone, 2019 Expand View Figure 21 Shipping (>24 metres) density in kilometres travelled (per 1/30 degree grid cell) for the Australian exclusive economic zone, 2019 km = kilometre Source: Based on Australian Maritime Safety Authority automatic identification system data. Share on Twitter Share on Facebook Share on Linkedin Share this link Marine vessel activity has affected environmental values (e.g. Hayes et al. 2004, Peel et al. 2018, IWC 2020, ATSB 2021), and future impacts on environmental values are likely to occur in local areas or to specific species. For example, the populations of many of the whale species at risk of ship strike are growing, leading to increased likelihood of collisions (Australian Marine Mammal Centre 2021). However, specific impacts may be countered by management improvements and mitigation. In addition to direct impacts, shipping is an important contributor of greenhouse gas emissions (Faber et al. 2021) (see the Climate chapter). At the beginning of 2020, the International Maritime Organization committed to halving greenhouse gas emissions by 2050, and there is growing demand for improved fuel efficiency within the marine transport sector in Australia and worldwide. Infrastructure and disturbance associated with shipping activity and ports are also important pressures in coastal environments (see the Coasts chapter). Growth in marine vessel activity Australia relies on sea transport for 99% (by volume) of its international trade (DIRD 2016). Since the 2016 state of the environment report, there has been a continued increase in shipping activity (Figure 22). In 2017–18, around 1,554 million tonnes of cargo were loaded (a 21.9% increase since 2013–14), and 155 million tonnes were discharged (2.6% increase) at Australian wharves by 5,859 vessels (6.5% increase) that made 34,117 port calls (18.8% increase; BITRE 2020). There has been a roughly 2% growth each year to 2020 in the number of cargo vessels (BITRE 2020), slowing from 4% growth reported in 2016. Future projections are for shipping to continue to increase (DIRD 2016). Although data on recreational boat registration are available and of good quality, they do not directly provide information on use and on-water spatial distribution. This means that it is not possible to determine trends in the pressures of marine vessels on the marine environment. Figure 22 Increase in number of cargo ships involved in coastal or international voyages that made port calls to Australian ports Expand View Figure 22 Increase in number of cargo ships involved in coastal or international voyages that made port calls to Australian ports Note: Dashed line indicates 2016 assessment time. Share on Twitter Share on Facebook Share on Linkedin Share this link Marine petrochemical and mineral industries Oil and gas exploration and extraction activities constitute the largest economic sector, by value, of Australia’s marine industries, with an estimated combined value of $36.3 billion in 2017–18 (AIMS 2021a). Natural gas production is the largest contributor, having grown in value from $16.9 billion in 2015–16 to $30.3 billion in 2017–18. Mining activity is currently restricted to coastal areas; although offshore seabed mining remains of considerable interest internationally, there has been no seabed mining activity in Australia, and no leases have been granted. Pressures associated with marine petrochemical and mineral industries Pressures associated with mineral, oil and gas extraction and production activities can include (Davies & Kingston 1992, Ronconi et al. 2015, Cuvelier et al. 2018, Miller et al. 2018a, Viola et al. 2018): removal of seabed and benthic habitat, including through blasting and dredging activities disturbance of seabed and benthic habitat from turbidity and sedimentation release of contaminants into the marine environment through uncontrolled releases (including spills as a result of failure of pressure control systems) and seepage disturbance to marine animals through noise, artificial light and air emissions (see Anthropogenic marine noise) potential introduction of introduced species. Activities associated with mineral, oil and gas extraction and production can alter animal movement and behaviours, largely as a response to the noise generated, but also as a consequence of unplanned releases from compromised wells (Newell et al. 1998, Farmer et al. 2018). Cumulative impacts may also arise from the effects of the activities of a single operation over time, from several operations within a particular area, or from interactions with other activities within the same area (Crain et al. 2008). Pressures associated with oil and gas extraction and production occur predominantly in offshore waters; activity is concentrated in the North-west and South-east marine regions (Evans et al. 2021b). Pressures associated with mineral extraction are limited to nearshore regions, including shell sand mining in Cockburn Sound (Western Australia), iron ore mining at Cockatoo and Koolan islands (Western Australia), sand mining in Moreton Bay (Queensland) and exploration for tin in Ringarooma Bay (Tasmania; NT EPA 2020). Assessing change in pressures from marine petrochemical and mineral industries Mineral mining activity has changed little since the 2016 state of the environment report (Evans et al. 2017), and oil and gas exploration has decreased nationally. The number of seismic surveys across both state waters (Western Australia, South Australia, Victoria) and offshore waters decreased from 128 in 2011–15 to 31 in 2016–20. Exploration, appraisal and development drilling activity in Western Australian and offshore waters declined, while activity in Victorian waters remained relatively stable, with 1 well drilled in 2011–15 and 2 wells drilled in 2016–20 (DEDJTR 2018, DJPR 2020). During 2015–20, oil production ceased at a number of facilities, and natural gas production commenced at 3 facilities in offshore waters. Production of crude oil declined in volume, and production of condensate and liquefied petroleum gas increased in volume (DISER 2020a). During 2016–20, 25 hydrocarbon/petroleum releases from offshore oil and gas operations (2–8 per year) that caused or had the potential to cause moderate to significant environmental damage were reported to the National Offshore Petroleum Safety and Environmental Management Authority, as required by the Offshore Petroleum and Greenhouse Gas Storage (Environment) Regulations 2009. The extent of mining and petroleum activity in Australian waters depends on investment decisions, product demand, commodity prices and existing work program commitments. Although there appears to be little change in mining activities in Australian waters currently, there is growing interest in marine mining globally, particularly in the exploration of deep-sea minerals (Miller et al. 2018a). Emerging industries in marine mining in state and territory waters (see the Coasts chapter) may translate into increasing pressures with these activities. As the oil sector continues to mature, it can be expected that oil exploration and production activities will decrease and decommissioning activities will grow (NOPSEMA 2020b). This will result in a shift in some pressures towards those associated with decommissioning activities, such as possible residual contamination, removal of infrastructure or re-purposing of infrastructure (Sommer et al. 2019). Continuing increases in gas production (APPEA 2020) and support from the Australian Government for expansion of gas activities (Morrison et al. 2020) will likely see the pressures associated with these activities increase. Offshore renewable energy generation Offshore renewable energy is yet to be deployed at large scale in Australia: to date, only small-scale (less than 500 kilowatt) experimental or prototype wave and tidal technologies have been deployed (Hemer 2021b). Several development proposals for large offshore wind farms (more than 100 megawatts) are progressing. The most mature proposal is for offshore eastern Victoria, currently undergoing environmental assessments under a Commonwealth exploration licence. Given the limited deployments, current pressures on the marine environment associated with offshore renewable energy are localised and sparse. However, these are likely to increase given the need to transition to renewable energy systems. Effects of deployments on local ecosystems are largely unknown, and are currently extrapolated from Northern Hemisphere assessments. Long-term monitoring and targeted research programs conducted overseas have identified environmental pressures associated with offshore wind farms (Hemer 2021b). A key pressure is noise associated with pile driving for fixed monopile turbine foundations during construction (see Anthropogenic marine noise). Less mature floating offshore wind technologies remove this pressure because they are not fixed to the seabed, but introduce potential other risks associated with collision or entrapment of marine animals with mooring lines. Collision risk between turbine blades and birds and bats is a concern, although the impact has been difficult to quantify offshore (Hemer 2021b). Scouring and changes to sediment transport, and biosecurity concerns associated with artificial reefing around turbine foundations, have also been identified as concerns (Tethys 2020). Closures or limitations to fishing within offshore wind farms have generally been associated with increased fish biomass (Degraer et al. 2019). Internationally, there has been a limited number of small-scale deployments of emerging technologies, including wave, tidal and ocean thermal systems. Environmental effects of concern with these technologies include collision risks between animals and devices, underwater noise, electromagnetic fields, changes in benthic and pelagic habitats, changes in oceanographic and coastal systems (in some cases by design as an engineering coastal protection measure), and encounters with device mooring systems and subsea cables. Understanding of many interactions has improved with recent demonstration projections. The potential environmental effects of offshore renewable energy devices on marine life are likely to be small or undetectable at their present scale. However, substantial uncertainties remain about the effects of future large arrays. Anthropogenic marine noise The main activities generating anthropogenic (human) noise in Australia’s marine environment are: geophysical surveys (seismic exploration using air gun arrays) sonars (military uses, scientific surveying, depth finders and fish-finding echo sounders) explosions (military exercises, port construction) pile driving (construction of wharves, ports and coastal infrastructure) vessels (recreational, transport, national and international freight) dredging (port, harbour and shipping routes) offshore platform activities (construction, operations and decommissioning) (Studds & Wright 2007). Seismic surveys in Australian waters have been concentrated in the main offshore oil and gas regions of the North West Shelf and Bass Strait (overview in the 2016 state of the environment report; Evans et al. 2017), military sonar concentrated in designated maritime exercise areas such as the Western Australian Exercise Area (near Perth) and the East Australian Exercise Area (near Sydney), and pile driving in major port development areas (e.g. expansion of the Port of Melbourne; PoM 2020). Noise generated by shipping is present around much of Australia; higher levels are generated in long shipping lanes with higher densities of vessel traffic (Peel et al. 2018). Noise generated by coastal activities (e.g. port construction, inshore commercial vessels, recreational activities) is concentrated in inshore regions adjacent to populated areas. Pressures associated with anthropogenic marine noise Sound is important for marine species for many purposes – for example, communication among individuals, alerting individuals to predators (or prey), navigating the marine environment and locating particular features (Tyack & Clark 2000, Montgomery et al. 2006, Popper & Hawkins 2019). Sounds from anthropogenic (as well as natural) sources have the potential to mask acoustic communication or sounds from the environment that animals might use, disrupt normal behaviours, induce stress, and cause temporary or permanent threshold shifts in hearing (Boyd et al. 2011, Williams et al. 2015b). Strong sounds can also cause physical damage to tissues and organs in fish (Popper & Hastings 2009, Casper et al. 2012). These pressures can ultimately have adverse impacts on foraging and reproduction, and individual health and fitness, which can affect overall population health (de Soto et al. 2013, de Jong et al. 2020). Assessing change in pressures from anthropogenic marine noise Human inputs of noise into the Australian marine environment are generally known, but the resulting soundscapes are poorly monitored (Evans et al. 2021e). Although a small number of acoustic observatories were implemented as part of the Integrated Marine Observing System National Mooring Network in 2009, these were ceased in 2017, with no further coordinated monitoring of the marine environment (IMOS n.d.). In the absence of soundscape monitoring, understanding the current state and recent trends of anthropogenic inputs of noise relies on assessing the activities that generate noise in the marine environment. The recent trend in noise is one of increasing input from shipping and decreasing inputs associated with oil and gas exploration (Evans et al. 2021e): The largest input of persistent, chronic anthropogenic noise into the marine environment is shipping (Studds & Wright 2007, McWhinnie et al. 2017). The number of vessels and the dead weight tonnage of the Australian trading fleet continue to increase (BITRE 2019), as does the number of cargo ships calling at Australian ports (BITRE 2019). Oil and gas exploration activities, a dominant contributor to acute impulsive noise in the marine environment, has declined (see Marine petrochemical and mineral industries). Looking forward, the long-term frequency and severity of strong impulsive noise in the offshore marine environment will remain, whereas activities generating continuous noise such as marine mining, marine renewable energy and shipping are expected to increase. Recent experimental evidence has showed that seismic survey activity had no detectable short- or long-term effects on tropical demersal fish populations on the North West Shelf of Western Australia (Meekan et al. 2021), but concerns remain for other taxa and in other regions. As offshore platforms for renewable energy expand, pile-driving activities associated with building infrastructure will also increase. Given the potential large-scale and long-term operational life of wind farms, there is uncertainty about the significance of increases in offshore anthropogenic noise in the future. It has been suggested that increased ocean acidification can reduce the absorption of sound and thus increase background noise levels (Brewer & Hester 2009, Gazioğlu et al. 2015), with potentially negative consequences for marine mammal and fish populations (e.g. Hester et al. 2008, Rossi et al. 2018, Radford et al. 2021). However, calculation of the actual effect has shown that the increase is likely negligible (Reeder & Chiu 2010, Udovydchenkov et al. 2010).