Performance and contribution to commercial catches and egg production by restocked Acanthopagrus butcheri (Sparidae) in an estuary

This study has explored whether the restocked fish of a species, which is confined to an estuary, perform as well as its wild stock, and has estimated their contribution to the commercial fishery and egg production. The biological characteristics of the 2001 and 2002 year classes of Acanthopagrus butcheri, which had been cultured and introduced into the Blackwood River in south-western Australia at seven and four months old, respectively, were thus determined from samples collected regularly between 2002 and 2014. The restocked fish could always be distinguished from the wild stock because their otoliths retained the pink colouration of the alizarin complexone with which they had been stained prior to release. Detailed analyses demonstrated the growth and maturity schedules of restocked fish were only slightly inferior to those of the wild stock and the mean gonad weights of the females of these two groups did not differ significantly in any month. As increasing numbers of restocked A. butcheri attained the MLL of 250 mm for retention, their contribution to the commercial fishery increased from 6% in 2005 to 74% in 2010. That contribution subsequently declined to 39% in 2012 and 10% in 2014, due predominantly to the introduction of the very strong 2008 year class in the commercial catches, the first substantial recruitment into the population since 1999. Restocked fish were estimated as contributing ~55% to the eggs produced in 2008, suggesting that substantial numbers of the 2008 year class were derived from spawning by restocked fish. The results of this and a previous genetic study imply that restocking is an effective and appropriate way for replenishing stocks of an estuarine species such as A. butcheri, especially as its recruitment is highly episodic

Risk and Emotion Among Healthy Volunteers in Clinical Trials

Theorized as objective or constructed, risk is recognized as unequally distributed across social hierarchies. Yet the process by which social forces shape risk and risk emotions remains unknown. The pharmaceutical industry depends on healthy individuals to voluntarily test early-stage, investigational drugs in exchange for financial compensation. Emblematic of risk in late modernity, Phase I testing is a rich site for examining how class and race shape configurations of emotion and risk. Using interview data from 178 healthy trial participants, this article examines emotion and risk as mutually constituting processes linked to biographical context and social structure. Biographical events like economic insecurity and incarceration influence how risk is felt by providing comparative experiences of felt risk and felt benefits. Such events, in turn, are structured by class-based and racial inequalities, linking class and race positions to primary emotional experiences of risk

Sediment removal in the lower Vasse River: Environmental Management Plan for Carter’s Freshwater Mussel Westralunio carteri

As part of the implementation of the Lower Vasse River Waterway Management Plan (City of Busselton, 2019), the City of Busselton proposes to remove sediment from an ~750 m reach of the Lower Vasse River in Busselton, Western Australia (WA) (hereafter primary Sediment Removal Site (‘SRS’)). An additional ~1700 m of river upstream may also be targeted for sediment removal in the future..

Two-Pion Exchange Nucleon-Nucleon Potential: Model Independent Features

A chiral pion-nucleon amplitude supplemented by the HJS subthreshold coefficients is used to calculate the the long range part of the two-pion exchange nucleon-nucleon potential. In our expressions the HJS coefficients factor out, allowing a clear identification of the origin of the various contributions. A discussion of the configuration space behaviour of the loop integrals that determine the potential is presented, with emphasis on cancellations associated with chiral symmetry. The profile function for the scalar-isoscalar component of the potential is produced and shown to disagree with those of several semi-phenomenological potentials.Comment: 16 pages, 9 embedded figures, Latex 2.09, Revtex.sty, epsf.st

Programs and Policies in Education, Crime and Justice and Social Welfare: Practical Recommendations Based on 14 Test-bed Reviews

Review teams tested the systematic review procedures and principles developed under the Campbell Collaboration. Fourteen review teams selected topics for intervention reviews in social policy, education, and criminal justice. Review protocols gave criteria for the extensive research literature search. Randomised Controlled Trials were selected. Systematic reviewers should give careful attention to defining the review topic, setting study inclusion and exclusion criteria, handling variability in outcome measurement and study reporting, appropriate uses of statistical meta-analysis, and reporting review results. Significant differences in review results were observed based on review criteria and procedures

Differential changes in production measures for an estuarine-resident sparid in deep and shallow waters following increases in hypoxia

This study determined how productivity measures for a fish species in different water depths of an estuary changed in response to the increase in hypoxia in deep waters, which had previously been shown to occur between 1993–95 and 2007–11. Annual data on length and age compositions, body mass, growth, abundance, biomass, production and production to biomass ratio (P/B) were thus determined for the estuarine-resident Acanthopagrus butcheri in nearshore shallow (<2 m) and offshore deep waters (2–6 m) of the upper Swan River Estuary in those two periods. Length and age compositions imply that the increase in hypoxia was accompanied by the distribution of the majority of the older and larger A. butcheri changing from deep to shallow waters, where the small fish typically reside. Annual densities, biomass and production in shallow waters of <0.02 fish m−2, 2–4 g m−2 and ∼2 g m−2 y−1 in the earlier period were far lower than the 0.1–0.2 fish m−2, 8–15 g m−2 and 5–10 g m−2 y−1 in the later period, whereas the reverse trend occurred in deep waters, with values of 6–9 fish net−1, 2000–3900 g net−1, 900–1700 g net−1 y−1 in the earlier period vs < 1.5 fish net−1, ∼110 g net−1 and 27–45 g net−1 y−1 in the later period. Within the later period, and in contrast to the trends with annual abundance and biomass, the production in shallow waters was least during 2008/09, rather than greatest, reflecting the slow growth in that particularly cool year. The presence of substantial aggregations of both small and large fish in shallow waters accounts for the abundance, biomass and production in those waters increasing between those periods and thus, through a density-dependent effect, provide a basis for the overall reduction in growth. In marked contrast to the trends with the other three production measures, annual production to biomass ratios (P/B) in shallow waters in the two years in the earlier period, and in three of the four years of the later period, fell within the same range, i.e. 0.6–0.9 y−1, but was only 0.2 y−1 in 2008/09, reflecting the poor growth in that year. This emphasises the need to obtain data on P/B for a number of years when considering the implications of the typical P/B for a species in an estuary, in which environmental conditions and the growth of a species can fluctuate markedly between years

Influence of bar opening on the fish fauna of Toby Inlet

Despite its catchment being subjected to substantial anthropogenic modification to support agriculture and urban development, Toby Inlet is highly valued by the community and considered to provide important habitat for fish and waterbirds. This study aimed to quantify these perceived biological values by determining the fish and benthic macroinvertebrate species present in the system and elucidate whether the number of species, abundance, diversity and faunal composition differed among regions of the estuary and/or changed when the bar at the mouth of Toby Inlet was closed (November 2017) and open (March 2018). A total of 12,438 fish from 17 species were recorded in the shallow, nearshore waters of Toby Inlet across the two sampling occasion. Most of these are short-lived, small-bodied (< 50 mm total length), belong to the atherinids and gobys and complete their life cycle within the estuary. While the mean number of species, density and diversity remained similar among regions and seasons, faunal composition changed following the opening of the bar, but this was mainly due to the timing of reproductive cycles of these typically short-lived (1 year life cycle) species. It also reflects the fact that these species are generally highly euryhaline and able to tolerate even the hypersaline conditions that occurred in the upper region in March. In contrast to nearshore waters, the 620 fish caught and released in the offshore waters comprised mainly marine species. The composition of this fauna changed markedly following the opening of the bar as only four species were recorded in November, increasing to 12 after the bar had been open for several months. All of the species recorded only in March spawn in marine waters and where able to recruit to the estuary as the bar was open and salinities had increased markedly, facilitating their survival in the estuary. The changes in faunal composition were mirrored by changes in mean number of species and catch rates, both of which were greater in March. Regional differences in fauna were also detected, due to the declining influence of these marine species in the upper estuary and Deadwater. This latter region contained an impoverished fauna due to its shallow depths and limited connectivity to the ocean (the Station Gully mouth was closed throughout the study) and the lower region of Toby Inlet. The benthic macroinvertebrate fauna, which was only sampled in November, comprised a range of insect, crustacean, annelid and mollusc species typically found in either wetland or estuarine environments. This reflects the low salinities at the time of sampling (2-8) and the connectivity of the system to wetlands upstream of Caves Road Bridge. While some, annelids and molluscs were found in each of the four regions, some wetland insects and amphipods were more common and abundant in the upstream regions (upper estuary and the Deadwater), whereas the reverse was true for several estuarine species of annelids and a bivalve. The opening of the bar, allowed the immigration and emigration of fish species from the estuary and increased salinity. This influenced the fish fauna in offshore more than nearshore waters, as most of these species breed in marine waters and thus require the bar to be open to be able to recruit to the estuary. As invertebrates were only sampled in November, when salinities, were very low, there would be value in repeating the sampling when salinities were greater to elucidate what effect bar opening may have on that fauna, particularly as many species of fish and birds use this fauna as a critical food source. It should be noted that sampling was only conducted in areas of downstream of Caves Road Bridge, but that an option to construct a second mouth in the upper region of Toby Inlet would influence the fauna in that region and thus there is a need to collect some baseline data from that area to allow the potential impacts to be explored. However, the data in this report provide a robust baseline against which future changes in the fauna of Toby Inlet could be detected and also may help in the development of management strategies to improve the health of this highly-valued estuary

Interdecadal changes in the community, population and individual levels of the fish fauna of an extensively modified estuary

This study examined inter-period changes over two to three decades in the fish fauna of an urbanized estuary experiencing rapid population growth and a drying climate (Swan-Canning Estuary, Western Australia). Responses were compared at the fish community level (species composition; 1978-2009 in the shallows and 1993-2009 in deeper waters) and at the population and individual levels of an estuarine indicator species, black bream Acanthopagrus butcheri (biomass-abundance and per capita mass at age, respectively; 1993-2009). All three levels showed distinct shifts from earlier to later periods, but their patterns, sensitivity and breadth differed. Community composition changed markedly in the shallows of the lower-middle estuary between the late 1970s and all later periods and moderately between more disparate periods from 1995 to 2009. Several species trends could be linked to the increasing salinity of the estuary or declining dissolved oxygen levels in its middle-upper reaches. Community changes were, however, small or insignificant in the shallow and deeper waters of the upper estuary and deeper waters of the middle estuary, where environmental perturbations are often most pronounced. This may reflect the resilience of the limited suite of species that typify those reaches and thus their lack of sensitivity in reflecting longer-term change at the coarser level of mean abundance. One such species, the selected indicator, A. butcheri, did, however, show marked temporal changes at both the population and individual levels. Biomass decreased markedly in deeper waters while increasing in the shallows from earlier to later periods, presumably reflecting an onshore movement of fish, and per capita body mass in the 2+, 3+ and 4+ year classes fell steadily over time. Such changes probably indicate deteriorating habitat quality in the deeper waters. The study outcomes provide support for a multifaceted approach to the biomonitoring of estuaries using fishes and highlight the need for complementary monitoring of relevant stressors to better disentangle cause-effect pathways