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Status of Fisheries Resources in NSW 2013-14.
... The coastline spans 10 degrees of latitude with overlapping subtropical and temperate faunal assemblages, resulting in high diversity. Over 140 species of fish, sharks, rays and invertebrates are harvested by nine commercial fisheries and various recreational and cultural fisheries across a range of habitats, from fresh water through to offshore marine (Stewart et al., 2015;West et al., 2015). Most extractive fishing occurs in near-shore and offshore areas of the continental shelf, and within the lower reaches of estuaries. ...
... Criterion 5) were distinguished from those that only require reporting at the state level. Exploitation status (Criterion 6) reflected the status assigned to stocks within NSW in the previous year (2017), following the rationale and definitions outlined in Stewart et al. (2015). Stocks for which NSW data contribute to stock assessments undertaken in other jurisdictions were distinguished from those without this requirement (Criterion 7). ...
... Some priority stocks do not require monitoring and assessment by NSW due to relevant monitoring and assessment from neighbouring jurisdictions. For example, NSW adopts the Commonwealth Government's assessment for Tiger Flathead (Platycephalus richardsoni), owing to the broad and crossjurisdictional distribution of the population and the small (<10% by weight) proportion of total catch taken by NSW (Stewart et al., 2015). Assessment of some priority stocks in the future may not require departmental funding, and therefore will not impact resource allocation, if cost recovery from industry occurs. ...
Prioritising fished stocks for monitoring and assessment is a challenge for management of resource-limited fisheries. We developed a participatory multi-criteria decision analysis (MCDA) to prioritise 141 fished stocks in New South Wales (NSW), Australia, based on their importance to fisheries management. The approach aimed to: (1) structure the decision problem, (2) force consideration of management objectives at the stock level, (3) balance trade-offs generated by competing objectives, and (4) balance differences in the perceived importance of objectives among fisheries managers. Performance scores and criteria weightings for ten management objectives were elicited from two groups of managers (commercial and recreational), combined into a total performance value for each stock, and ordered to infer priority for assessment. Stocks with higher total performance values typically had an exploitation status of Overfished, Growth-overfished, or Uncertain and were subject to a catch quota, because these criteria were weighted highly by both management groups. However, total performance was more sensitive to differences in weightings between management groups than to variations in relative magnitude of weightings among criteria. The priority list of stocks will assist decisions regarding the optimal allocation of resources for fisheries research in NSW. This MCDA approach is adaptive and can incorporate changes in management priorities through time and additional ecosystem components.
... elevated abundance in no-take zones is not surprising as this species does appear to come under considerable fishing pressure. For example in New South Wales this species is fully fished(Stewart et al. 2015) and although this species is not considered to be over fished, it is caught in large quantities by both the commercial trap and line fishery(Stewart et al. 2015) and recreational fishers(West et al. 2015). ...
... elevated abundance in no-take zones is not surprising as this species does appear to come under considerable fishing pressure. For example in New South Wales this species is fully fished(Stewart et al. 2015) and although this species is not considered to be over fished, it is caught in large quantities by both the commercial trap and line fishery(Stewart et al. 2015) and recreational fishers(West et al. 2015). ...
... The pattern of the largest fish within NTZs and the smallest in OAs aligned with my predictions, however the magnitude of difference between zones was relatively small. There is no stock assessment for this species in NSW(Stewart et al. 2015) and it is difficult to know the level of commercial fishing pressure P. grandispinis is experiencing, however my results suggest that it is sufficient for management zones to have a small effect. In addition, P. grandispinis is also caught unintentionally by fishers targeting Platycephalus caeruleopunctatus who often assume they are P. caeruleopunctatus (Authors pers. ...
Marine protected areas (MPAs) are an increasingly common management approach to assist in conserving marine biodiversity by limiting, avoiding or removing anthropogenic activities such as pollution, habitat destruction and fishing. Globally, a considerable proportion of the area under protection in MPAs comprises soft sediments. Research on rocky reefs and coral reefs has demonstrated that when MPAs are well designed and implemented, the abundance and biomass of targeted fish species can increase. However, demersal fish on marine soft sediments have been poorly studied and it remains unclear whether they respond in the same ways to protection as fish on other habitats. In this thesis, I aimed to assess (i) whether MPA protection in south-east Australia has affected the species composition, abundance and size of demersal marine soft sediment fishes among management zones and (ii) the degree of long-term residency shown by a key recreationally and commercially targeted species in relation to MPA size and zoning.
First, I used baited remote underwater videos (BRUVs) to sample the fish assemblages and test hypotheses about the effects of MPA management and implementation. My results revealed that in, shallow (10 m), deep (20 m) and offshore (50–60 m) waters, the demersal soft sediment fish assemblages were characterised by a few frequently occurring species. At all depths sampled the most common species were flathead (Platycephalus caeruleopunctatus & Platycephalus grandispinis). Shallow- and deepwater BRUV sampling was carried out between May and June in 2011, 2013 and 2015, within Jervis Bay Marine Park. At the assemblage level, no impact of MPA zoning was detected at either depth. There was also no difference between zones in total relative abundance (abundance of all species combined) or species richness at either depth. Abundances of individual species (those appearing on ≥ 25% of BRUVS samples) were also compared between zones; In shallow-water, there was a 32% greater abundance of Platycephalus spp. in no-take zones (NTZs) compared to partially protected areas (PPAs) over the study. In addition, abundances were more stable in NTZs across time. In shallow-water, Eastern fiddler ray (Trygonorrhina fasciata) and shovelnose ray (Aptychotrema rostrata), also had higher abundances in NTZs compared to PPAs in 2015. In deep-water there were no differences between zones for any individual species. There were no differences in length of flathead between zones at either depth. Offshore comparisons were carried out between August 3 and December in 2015, within Jervis Bay Marine Park, Batemans Marine Park and open access (OA) areas outside the two MPAs. Assemblages showed clear differences among NTZ, PPA, and fished OA areas. At the species level, on average, larger individuals of longspine flathead (P. grandispinis) were observed in NTZs than in both PPAs and OAs. There were also substantially higher abundances of ocean jackets (Nelusetta ayraudi) in NTZs. In offshore water there were no differences in abundances among zones for any other species or in species richness and total relative abundance.
Second, I tested the assumption that fish on soft sediments are unlikely to show residency by evaluating the movement patterns of the bluespotted flathead (P. caeruleopunctatus) in Jervis Bay Marine Park. Bluespotted flathead were acoustically tagged within a NTZ in spring 2014 (n=25), autumn 2015 (n=15), and summer 2015 (n=6). I then monitored the tagged fish for 625 days. Bluespotted flathead exhibited small-scale and long-term residency within the NTZ. Over the first 108 days post tagging most fish (74%) remained within a ~200 ha area of NTZ and were detected frequently. I observed residency of up to 600 days. Although close to two thirds of the tagged fish were only detected within Jervis Bay, the remainder were detected moving up to 155 km from where they were tagged. Generally, these fish had a prolonged period of site residency before making these large-scale movements. Importantly, range testing confirmed that acoustic tags in this habitat were detected with a high degree of confidence and reliability.
My findings demonstrate that temperate demersal fishes found on marine soft sediments can be influenced by protection within MPAs at a number of spatial scales. However, the response is highly variable among species with the majority showing no response, a relatively small effect size for those that do show a response and assemblage wide responses occurring in offshore waters but not within nearshore waters. In conclusion, marine soft sediments are an extensive habitat that harbour a unique demersal fish community. This habitat supports an important component of marine biodiversity and represents a rich fishery resource. This study provides a rare example of MPA effects on demersal soft sediment assemblages and presents substantial evidence of long-term residency by a demersal soft sediment associated fish within an NTZ
... Colloquially known as sea mullet in Australia, M. cephalus represent a single biological stock along eastern Australia, extending from central Queensland to eastern Victoria ( Stewart et al. 2016). The stock is heavily exploited, with annual commercial fishery landings in south-eastern Australia being generally greater than any other coastal or estuarine species in the region ( Stewart et al. 2015). Annual commercial landings across this stock have been in the order of 5000-6000 Mg year À1 since 2006 ( Stewart et al. 2015Stewart et al. , 2016). ...
... The stock is heavily exploited, with annual commercial fishery landings in south-eastern Australia being generally greater than any other coastal or estuarine species in the region ( Stewart et al. 2015). Annual commercial landings across this stock have been in the order of 5000-6000 Mg year À1 since 2006 ( Stewart et al. 2015Stewart et al. , 2016). Most of the catch comes from the state of New South Wales (NSW) ( Stewart et al. 2015Stewart et al. , 2016), where it is targeted by two separate fisheries that each captures roughly 50% of the annual catch. ...
... Annual commercial landings across this stock have been in the order of 5000-6000 Mg year À1 since 2006 ( Stewart et al. 2015Stewart et al. , 2016). Most of the catch comes from the state of New South Wales (NSW) ( Stewart et al. 2015Stewart et al. , 2016), where it is targeted by two separate fisheries that each captures roughly 50% of the annual catch. There is a mesh and seine net fishery in estuaries that occurs throughout the year targeting fish primarily for human consumption, and a beach seine fishery on open coastal beaches that targets prespawning aggregations during their annual northerly migration between March and July each year ( Stewart et al. 2015). ...
Understanding mechanisms supporting the resilience of exploited fish populations is fundamental to sustainable management. Herein we identify sex-specific differences in life history traits that confer resilience in the heavily exploited population of Mugil cephalus along eastern Australia. M. cephalus in this region emigrate from estuaries and undergo an annual northerly spawning migration that is dominated by males. Males mature, on average, at younger ages than females and were most abundant in the spawning migration at age-4, whereas females were most abundant at age-5. Females grew significantly faster and larger than males, with both sexes being aged up to 14 years. These sex-specific differences relate directly to the population stability of M. cephalus under the reproductive strategy of a spawning migration. Males participate in the spawning migration at younger ages and in greater numbers than females to ensure a sufficient number of males for successful spawning. Females partition more energy to growth than males, maturing and participating in the spawning migration at older ages and larger sizes. The larger body size of females is related to increased fecundity, increased survivorship and more efficient swimming ability. These traits, combined with population strategies of both delayed and skipped spawning, convey substantial resilience.
... Functional and feeding traits for each fish species (Table S2) were obtained from FishBase (http:// fishbase.org accessed January 2018), the global fishes trait database, 23 as well as from Coleman et al. 18 and Davis et al. 24 Target species were those routinely harvested by commercial and recreational fishers and defined as those listed in the NSW Status of the Fisheries Report, 25 the Stock Status of Queensland's Fisheries, 26 the NSW saltwater recreational fishing guide, 27 and the Queensland boating and recreational fishing guide. 28 All remaining fish were considered nontarget species. ...
... Silver sweep is considered to be a fully fished species (i.e., catch rates are stable and spawning biomass is greater than 30% of the unfished biomass) that is relatively long-lived, with more than 50% of landings being individuals that are more than 15 years old. 25,43 As a relatively small fish, the enhanced abundances of silver sweep around the desalination outlet are unlikely to drive shifts in fishing effort. In contrast, grey morwong is a sought after species that is overfished (i.e., spawning biomass is less than 20−30% of the unfished spawning stock) and local aggregations warrant greater consideration by fisheries management agencies. ...
... Although the effects were generally small or inconsistent across bioregions, these groups and species should be highlighted for future monitoring to assess any further declines and the potential need for further management action. For labrids, the NTMR effects are most likely to due to recreational and commercial fishing interest in these species in NSW waters (Stewart 2011, Stewart et al. 2015, West et al. 2015 and the likelihood of high levels of residency of labrids over small spatial scales on rocky reefs (Barrett 1995, Edgar et al. 2004, Kingsford and Carlson 2010, Lee et al. 2015). An intriguing pattern appeared with the gregarious reef species, Scorpis lineolata, which are targeted by commercial and recreational fishers Hughes 2005, West et al. 2015), as it showed higher relative abundance in NTMR than in fished areas. ...
... In this state-wide comparison, there were no obvious or consistent responses to NTMR protection for a range of other targeted species (West et al. 2015), such as Nemadactylus douglasii, Cheilodactylus fuscus, and various monacanthids which are (or are likely to be) resident species on NSW rocky reefs (Barrett 1995, Lowry and Suthers 1998, Edgar et al. 2004, Curley et al. 2013, Stewart et al. 2015. Nemadactylus douglasii is assessed as a depleted stock , and a stock rebuilding plan is to be developed for this species (Stewart and Hughes 2009, Stewart 2015a, NSW DPI 2018; and Cheilodactylus fuscus have been observed to often respond to NTMR protection (Barrett et al. 2008, Coleman et al. 2013, Malcolm et al. 2015a. ...
Worldwide, several countries have established coherent, representative, and large-scale networks of marine reserves to conserve biodiversity. Very few have, however, published systematic assessments of the ecological responses to this network protection, hindering broad understanding of their generality, utility, and efficacy. We present data collected from systematic sampling of rocky reef fish assemblages at sites across a network of 27 no-take marine reserve areas (NTMR) and 27 partially protected areas (PPA) nested within multiple marine parks (regional networks) across three Australian bioregions
spanning >1000 km of coastline (7° latitude) to test the generality of ecological change across this network. We also sampled 18 reference areas (outside of the marine parks) to provide an independent assessment of potential NTMR effects and also to assess whole marine park effects. Baited remote underwater video (BRUV) was used to sample fishes between depths of 20–40 m over austral winters in four years (2010, 2011, 2015, and 2016). Despite substantial bioregional differences in fish assemblages, large and consistent effects of NTMR protection were detected across all bioregions for a key commercially and recreationally harvested species, Chrysophrys auratus (pink snapper). There were substantial increases in relative abundance of C. auratus in NTMR compared with fished zones through time (effect sizes >150%). The wider assemblage of targeted fish (excluding C. auratus) only showed relatively small effects of protection (~11%) with trends observed for site-attached wrasses (labrids) and planktivores (e.g., commercially
fished Scorpis lineolata) that are recreationally and commercially harvested. Furthermore, the relative abundance of non-target or by-catch species generally did not differ among management zones across the bioregional network. These results highlight how NTMR can be used to assess the ecological effects of fishing and wider environmental management, and can be incorporated into ecosystem-based management for reef species more generally. Importantly, the provision of robust evidence of the performance and generality of NTMR over large-spatial scales (e.g., bioregions) provides greater confidence in the expected outcomes from marine reserve networks as a conservation management approach.
... Functional and feeding traits for each fish species (Table S2) were obtained from FishBase (http:// fishbase.org accessed January 2018), the global fishes trait database, 23 as well as from Coleman et al. 18 and Davis et al. 24 Target species were those routinely harvested by commercial and recreational fishers and defined as those listed in the NSW Status of the Fisheries Report, 25 the Stock Status of Queensland's Fisheries, 26 the NSW saltwater recreational fishing guide, 27 and the Queensland boating and recreational fishing guide. 28 All remaining fish were considered nontarget species. ...
... Silver sweep is considered to be a fully fished species (i.e., catch rates are stable and spawning biomass is greater than 30% of the unfished biomass) that is relatively long-lived, with more than 50% of landings being individuals that are more than 15 years old. 25,43 As a relatively small fish, the enhanced abundances of silver sweep around the desalination outlet are unlikely to drive shifts in fishing effort. In contrast, grey morwong is a sought after species that is overfished (i.e., spawning biomass is less than 20−30% of the unfished spawning stock) and local aggregations warrant greater consideration by fisheries management agencies. ...
Global growth in desalination industries has increased the need for an evidence-based understanding of associated environmental impacts. We completed a seven-year assessment of the responses of fish assemblages to hypersaline discharge from the large Sydney Desalination Plant. At 12 times before, eight times during, and four times following the cessation of discharging hypersaline brine, we sampled reef fishes at two outlet sites and two close reference sites, as well as four reference sites that were located from 2-8 km from the outlet. At each site and each time of sampling, five 50 m video transects were used to sample reef fish assemblages. Following the commencement of discharging, there was a 279% increase in the abundance of fish around the outlet, which included substantially greater abundances of pelagic and demersal fish, as well as fishes targeted by recreational and commercial fishers. Following the cessation of discharge, abundances of fishes mostly returned to levels such that there was no longer a significant effect compared to the period prior to the commencement of the desalination plant's operations. Overall, our results demonstrate that well-designed marine infrastructure and processes used to support the growing demand for potable water can also enhance local fish abundances and species richness.
... As larger fish have higher fecundity (Koops et al., 2004), the presence of the larger size classes can contribute to the marine park objectives relating to ecological integrity and function (NSW MEMA, 2017b). In addition, as snapper has been classed as growth overfished in NSW and grey morwong are overfished, larger individuals may contribute to ongoing management of these species at a local or regional scale (NSW DPI, 2017;Stewart et al., 2015), although many factors influence reproductive resilience in exploited marine fish (Lowerre- Barbieri et al., 2017). The exploitation status of the other two target species is uncertain (pearl perch) or not defined (venus tuskfish) in NSW, so management that supports larger and potentially older individuals is desirable from a precautionary approach. ...
... Malcolm et al. Estuarine, Coastal and Shelf Science 212 (2018) 118-127 catches and lengths of grey morwong steadily declining since the early 1980s and a recreational catch about three times higher than commercial catch in NSW (NSW DPI, 2017;Stewart et al., 2015;Stewart and Hughes, 2009), an increase in abundance and length in 'no take' zones could be expected, as was found (Barrett et al., 2007;Chiappone et al., 2000;Westera et al., 2003). There were few differences between partially protected areas inside the marine park and fished areas outside the marine park in our study, in relation to abundance and length of the species examined. ...
The influence of ‘no take’ Marine Protected Areas (MPAs) on abundance and size of fishes varies considerably and the likely benefits are still debated. Meta-analyses reveal findings are biased towards studies in shallower depths suitable for diving surveys. Empirical comparisons in deeper waters, including among areas with differing spatial management, further contribute to understanding of MPA benefits and constraints. We compare length and abundance of commercially and recreationally targeted fishes (and bycatch) among management types within and adjacent to the Solitary Islands Marine Park (SIMP), Australia. Sampling was done on reefs between 25 and 40 m depth in ‘no-take’ and fished ‘partially protected’ areas within the marine park and fished areas outside the SIMP, using stereo- Baited Remote Underwater Videos (stereo-BRUVs) at eight, nine, thirteen and fourteen years after these ‘no take’ areas were established. Four species targeted by fishers: snapper Chrysophrys auratus, grey morwong Nemadactylus douglasi, pearl perch Glaucosoma scapulare, and venus-tuskfish Choerodon venustus, were more abundant and larger in ‘no take’ zones overall and showed an increase through time in ‘no take’ relative to both types of fished area. In contrast, there was no distinct pattern of four bycatch species increasing in abundance in ‘no-take’ areas. Abundances of fish in partially protected areas were similar to fished areas outside the MPA. This study adds empirical evidence to the assertion that ‘no take’ areas in particular, can contribute to both marine conservation and natural resource management.
... In response to concerns over stock status and in the absence of detailed population assessments, the minimum SMO in lampara nets was increased to 28 mm (initiated in 2006 but not fully adopted until 2009-10 as fishers replaced their existing nets) and effort was reduced. These input controls resulted in the fishery constantly landing ~45-50 t per annum (Stewart et al., 2015). Ancillary recreational (mostly hook-and-line) catches of H. australis are minor (<5 t per annum; Henry and Lyle, 2003); only ~15% of which are discarded, and with variable associated mortality, depending on their handling (Butcher et al., 2010). ...
... Results of fitted mortality models (ranked by increasing value of log-likelihood) estimating the natural mortality ( ) catchability and selectivity (all ± SE) for eastern sea garfish, Hyporhamphus australis off south eastern Australia between 2004 and 2015.Table 2. Estimates of annual fishing mortality ( ) at age, based on mortality model 2 (which estimated a vector of four parameters; natural mortality ( ), catchability and a change in selectivity from age 0-1 years onwards) for eastern sea garfish, Hyporhamphus australis off south eastern Australia between 2004 and 2015.Fig. 1. Historical (2004-2015 variation among catches (t) and fishing effort (boat-days) for the lamparanet fishery targeting eastern sea garfish, Hyporhamphus australis off south eastern Australia. ...
Estimates of age-specific natural (M) and fishing (F) mortalities among economically important stocks are required to determine sustainable yields and, ultimately, facilitate effective resource management. Here we used hazard functions to estimate mortality rates for eastern sea garfish, Hyporhamphus australis, a pelagic species that forms the basis of an Australian commercial lampara-net fishery. Data describing annual (2004 to 2015) age frequencies (0-1 to 5-6 years), yield, effort (boat-days), and average weights at age were used to fit various stochastic models to estimate mortality rates by maximum likelihood. The model best supported by the data implied: (i) the escape of fish aged 0-1 years increased from approximately 90 to 97% as a result of a mandated increase in stretched mesh opening from 25 to 28 mm; (ii) full selectivity among older age groups; (iii) a constant M of 0.52 +- 0.06 per year; and (iv) a decline in F between 2004 and 2015. Recruitment and biomass were estimated to vary, but increased during the sampled period. The results reiterate the utility of hazard functions to estimate and partition mortality rates, and support traditional input controls designed to reduce both accounted and unaccounted F.
... Recreational fishers in NSW harvest substantial quantities of many commercially valuable stocks, exceeding commercial catch for numerous species (West et al., 2015;Murphy et al., 2020). Yet stock assessments in NSW rarely incorporate recreational data (Stewart et al., 2015), and monitoring of RF has been infrequent and sporadic to date (Henry and Lyle, 2003;West et al., 2015;Murphy et al., 2020). ...
Recreational fishing (RF) is a popular pastime resulting in substantial fish mortality in many regions. Yet inclusion of RF in fishery harvest strategies is limited, because the sector's objectives are poorly understood, as are the data required to track their performance. To address this, we reviewed RF data sources available from a region of globally high participation (New South Wales [NSW], Australia) and evaluated their utility for RF-specific performance indicators within harvest strategies. We then linked these data sources to RF objectives they may be used to monitor. A total of 21 RF data sources were identified in NSW over the past two decades, spanning all major aquatic environments and 146 fished species. Numerous data sources were available to monitor ecological objectives, providing time-series and potential reference points for key indicators such as catch-per-unit-effort. Few data sources were available for social, economic, and institutional objectives, consistent with a global paucity of these data. We found that most social objectives of RF lie outside the scope of traditional harvest strategies, although some are linked to underlying ecological performance. Harvest strategy performance for RF will depend on the relative importance of social objectives and whether these can be achieved by controlling harvest.
... The species is also a highly prized recreational target species with an estimated 260 t landed in 2013/14, again with a substantial proportion (103 t) taken in NSW waters (West et al., 2015;Earl et al., 2018). Heavy historical exploitation of the species has resulted in an 'overfished/depleted' assessment of the NSW component of the stock since 2004/05 (Silberschneider et al., 2009;Stewart et al., 2015;Earl et al., 2018) and has recently been subject to significant management changes in an effort to arrest the decline in A. japonicus fisheries there (Silberschneider et al., 2009;Earl et al., 2018). ...
Information on the movements and population structure of an exploited fish species is vital for determining the appropriate spatial scale at which management should occur to ensure sustainable harvesting. However, such information exists for very few exploited species. Large-scale patterns and drivers of movement were examined for an iconic recreational sciaenid species, mulloway (Argyrosomus japonicus), in coastal eastern Australia using an angler-assisted tag-recapture dataset. Over 4300 individuals were tagged and released across 1005 km of coastline over three decades (1988-2017). Six-hundred and fifty-seven individuals were subsequently recaptured at a rate of 15.1% over the same time period. Average time at liberty was 216 (±9) days (range: 0-1954 days), with distances moved ranging from 0 to 355 km. Median movement distance was 4 km, and a large proportion of individuals (73%) were recaptured within 10 km of release locations. Thirty one percent of individuals were recaptured at release locations (< 1 km) and 81% in the same estuary. However, 7% moved distances of > 100 km. Generalised additive modelling revealed that release latitude, body size and time at liberty were significant predictors of distance moved. Greater distances moved were observed for fish tagged at lower latitudes, at larger sizes and over longer periods at liberty. Results indicate that A. japonicus are primarily restricted to small movements (< 10 km) in eastern Australia and display strong site fidelity, despite being capable of movements over larger scales (100s of km). This spatial scale of movement is also much smaller than the current 'jurisdic-tional' scale of management in this region (~1000 km). Assessment and management of A. japonicus in eastern Australia may therefore need to be reexamined considering these findings and potentially undertaken at more localised spatial scales in the future. This study also highlights the importance of citizen science in the cost-effective generation of a sufficiently broad spatio-temporal dataset required to detect the movement patterns revealed here.
... Initially, biomass enhancement of economically relevant fish was combined with commercial catch data from the latest available fisheries reports: New South Wales (Stewart et al., 2015), Victoria (Department of Primary Industries, 2012); and South Australia (PIRSA, 2015). From these reports, the most recent 3-year annual catch statistics (catch in tonnes and AUD value) of economically important species were extracted. ...
Coastal ecosystems are estimated to support 95% of the world’s commercially-important fish, owing largely to their provision of nursery habitat for juveniles; however, systematic databases with such data are scarce. By systematically reviewing the literature across Australia, we quantified fisheries enhancement from three key coastal vegetated habitats: seagrass meadows, mangrove forests, and tidal marshes. From juvenile densities, we modelled adult fish biomass enhancement resulting from these structured habitats and linked fish of economic importance with market values. We found that seagrass displayed higher per hectare abundance, biomass and economic enhancement compared to mangroves and tidal marshes. On average, one hectare of seagrass supported 55,000 more fish annually compared to unvegetated seabed, resulting in an additional biomass of 4000 kg and a value increase of AUD 21,200 annually. Mangroves supported 19,000 more fish, equivalent to 265 kg⁻¹ ha⁻¹ y⁻¹, and tidal marshes provided a modest 1700 more fish, equivalent to 64 kg⁻¹ ha⁻¹ y⁻¹. The most abundant fish across all ecosystems were small, non-commercial species (e.g. gobies and glassfish), but the highest biomass and economic value originated from larger, longer-lived fish that are regularly targeted by fisheries (e.g. breams and mullets). By quantifying enhancement value across Australia, our findings provide further evidence for, the benefit these critical habitats provide in supporting coastal fisheries and human well-being.
... According to a Commonwealth assessment of sawshark catch data , standardised catch rates of both species were below 40% of their initial catch rate 1 decade ago, prompting concern over whether the current status as not overfished is appropriate. In NSW waters, the population status of sawsharks is classified as 'undefined' and information on population trends that guides formal classification would be used to manage these species (Peddemors 2015;Stewart et al. 2015). Conventional satellite tagging (pop-up satellite tags and Argos) is not as effective at these depths for benthic animals, and sawsharks are known to have a low tolerance to capture that would be required for tagging (Braccini et al. 2012). ...
Sawsharks are one of the least well-known groups of sharks globally, yet they are caught in large numbers in south-eastern Australia. In this study we assessed spatiotemporal patterns of distribution of two co-occurring species of sawsharks, namely the common sawshark (Pristiophorus cirratus) and the southern sawshark (Pristiophorus nudipinnis), to guide future research in this area. To identify where the animals may occur in greater numbers, this study used the major commercial fishery datasets in the region, containing nearly 180000 catch records from 1990 to 2017. Several general patterns were evident. Sawsharks occurred at shallower and deeper depths than previously thought, and their geographical range was larger than documented in previous studies. Depth distributions of both species overlapped, but P. cirratus appeared more common in deeper water (at depths up to 500m), with peak common sawshark catch rates at ~400m. Seasonal standardised catch patterns across fishing methods suggested that migrations from deeper to shallower waters may occur in the Australasian autumn and winter. The greatest concentration of sawsharks, inferred by standardised catch rates, occurred to the east and west of Bass Strait between Tasmania and mainland Australia. Although standardised catch rates of sawsharks declined in gill-net fisheries by ~30%, primarily in the Bass Strait and Tasmania, sawsharks appear to be caught at consistent rates since the 1990s, inferring a possible resilience of these sharks to current levels of fishing pressure.
... The population of A. japonicus in eastern Australia has been historically fished down to the extent that it exhibits extreme age class truncation, with relatively few fish older than 5 years of age in commercial landings (Stewart, 2011). Age class truncation in such populations, whereby the reserve of older fish is removed through fishing (Beamish et al., 2006), reduces resilience to environmental variation with sometimes catastrophic consequences (Longhurst, 2002 (Stewart et al., 2015), and substantial management changes designed to promote stock recovery were introduced in 2013, including raising the minimum legal length to the estimated size at 50% maturity (70 cm TL) and reductions in recreational and commercial catch limits; however stock recovery has yet to be detected (Earl et al., 2018). Our results suggest that stock recovery of A. japonicus will likely only occur following periods of relatively high rainfall and associated stronger year class strengths. ...
Freshwater flows into estuaries influence fish populations through effects on recruitment, growth and mortality. We compared year class strength of a large sciaenid Argyrosomus japonicus with rainfall through a 16-year period in southeastern Australia, to understand the influence of freshwater input on this estuary-dependent and depleted population. Relative year class strength, estimated by back-calculating age composition data from commercial fishery landings, was positively related to rainfall within estuarine catchments (R² = 52%). Commercial estuarine landings from a separate 29-year dataset were positively related to rainfall two and three years earlier (R² = 21% and 44%, respectively). Year class strength of a key prey species, the penaeid prawn Metapenaeus macleayi, was also related to year class strength of A. japonicus (R² = 39%), suggesting that rainfall influences recruitment of A. japonicus by affecting food availability. Several years of above average rainfall may be required to promote recruitment substantial enough to rebuild the population.
... The mud crab (Scylla serrata), also known as the giant mud crab, mangrove crab (Johnson, 2015) or green mud crab (Department of Fisheries, 2013), 1 can be found throughout the Indo-Pacific region, including the east and the west coasts of India. Due to its relatively large size and delicate meat, it is in growing demand and is one of the economically most important species in coastal regions (Le Vay, 2001). ...
Knowledge of reproductive biology and life-history traits of populations exploited by fisheries is important for their sustainable management. We investigated the life-history traits of Trichiurus lepturus (largehead hairtail) in south-eastern Australia; a region of low exploitation for this otherwise heavily exploited circumglobal species, to investigate whether there were differences in the reproductive biology and life-history traits in the south-east Australian population compared with those in other regions. We also used histological sections to examine male and female gonads at a microscopic level. Trichiurus lepturus in south-eastern Australia had a greater maximum length (193 cm total length (TL)), matured at a larger length (108 cm TL at 50% mature) and had a spawning period (March to September, Austral winter) that was inconsistent with other regions. The overall sex ratio of 1:0.4 females: males was consistent with a female dominant sex ratio observed in other regions, particularly in larger length classes. However, females in the current study dominated samples from both estuarine and coastal habitats, as well as during the spawning and non-spawning periods, which is not consistent with the patterns found in other regions. Differences in south-eastern Australia may relate to limited fishing pressure, genetic variation, or differences in environmental factors that influence reproductive development, including temperature, trophic resources and habitat.
Delineation of population structure (i.e. stocks) is crucial to successfully manage exploited species and to address conservation concerns for threatened species. Fish migration and associated movements are key mechanisms through which discrete populations mix and are thus important determinants of population structure. Detailed information on fish migration and movements is becoming more accessible through advances in telemetry and analysis methods however such information is not yet used systematically in stock structure assessment. Here, we described how detections of acoustically tagged fish across a continental-scale array of underwater acoustic receivers were used to assess stock structure and connectivity in seven teleost and seven shark species and compared to findings from genetic and conventional tagging. Network analysis revealed previously unknown population connections in some species, and in others bolstered support for existing stock discrimination by identifying nodes and routes important for connectivity. Species with less variability in their movements required smaller sample sizes (45-50 individuals) to reveal useful stock structure information. Our study shows the power of continental-scale acoustic telemetry networks to detect movements among fishery jurisdictions. We highlight methodological issues that need to be considered in the design of acoustic telemetry studies for investigating stock structure and the interpretation of the resulting data. The advent of broad-scale acoustic telemetry networks across the globe provides new avenues to understand how movement informs population structure and can lead to improved management.
Wild capture fisheries provide substantial input to the global economy through employment and revenue. The coastal zone is especially productive, accounting for just 7% of the total area of the ocean, but supporting an estimated 50% of the world's fisheries. Vegetated coastal ecosystems—seagrass meadows, tidal marshes and mangrove forests—are widely cited as providing nutritional input that underpin coastal fisheries production; however, quantitative evidence of this relationship is scarce. Using Australia as a case study, we synthesized fisheries stable isotope data to estimate nutritional input derived from coastal vegetated ecosystems and combined these “proportional contribution” estimates with total annual catch data from commercial fisheries to determine species‐specific dollar values for coastal vegetated ecosystems. Based on the data from 96 commercially important fish species across Australian states (total landings 14 × 106 tonnes pa), we provide a conservative estimate that Australia's coastal vegetated ecosystems contribute at least 78 million AUD per year to the fisheries economy. Two thirds of this contribution came from tidal marshes and seagrasses that were both equally valued at 31.5 million AUD per year (39.4%) followed by mangroves at 14.9 million AUD per year (18.6%). The highest dollar values of coastal ecosystems originated from eastern king prawn (Melicertus plebejus) and giant mud crab (Scylla serrata). This study demonstrates the substantial economic value supported by Australia's coastal vegetated ecosystems through commercial fisheries harvest. These estimates create further impetus to conserve and restore coastal wetlands and maintain their support of coastal fisheries into the future.
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