Assessing population sustainability and response to fishing in terms of aggregation structure for greenlip abalone (Haliotis laevigata) fishery management

2004 ◽  
Vol 61 (2) ◽  
pp. 247-259 ◽  
Author(s):  
Natalie A Dowling ◽  
Stephen J Hall ◽  
Richard McGarvey
Keyword(s):  
Egg Production ◽  
Fishery Management ◽  
Management Strategies ◽  
South Australia ◽  
Fertilization Success ◽  
Adult Density ◽  
Demographic Feature ◽  
Data Set ◽  
Functional Relationships ◽  
Aggregation Size

The greenlip abalone (Haliotis laevigata) population in Waterloo Bay, South Australia, has undergone collapse and fishery closure twice since 1978. A rich data set, including survey measures of degree of spatial aggregation, has been gathered over that time and provides a unique opportunity to identify factors accounting for persistence or collapse, an issue that is of significance to abalone fisheries worldwide. Statistical analyses of fishery and survey data were undertaken to infer functional relationships between catch, effort, recruitment, adult density, and extent of aggregation. Catch rates were hyperstable, an observation consistent with the targeting of large aggregations. Statistical analysis of recruitment showed a significant year effect, implying an environmental signal, and suggested that aggregation size impacts fertilization success. Aggregation size grew under closure, suggesting an impact of fishing on this demographic feature. Aggregative behaviour appears to be critical for subpopulation sustainability. Fishery collapse may be triggered by depletion of larger abalone aggregations by heavy fishing, resulting in declines in fertilized egg production. When heavy fishing coincides with unfavourable environmental conditions, recruitment may be insufficient to sustain the subpopulation. If aggregation is similarly critical for other subpopulations, management strategies could be adapted according to the extent of aggregation in each subpopulation.

scholarly journals The dangers of ignoring stock complexity in fishery management: the case of the North Sea cod

2008 ◽  
Vol 4 (6) ◽  
pp. 693-695 ◽  
Author(s):  
William F Hutchinson
Keyword(s):  
North Sea ◽  
Egg Production ◽  
Gadus Morhua ◽  
Fishery Management ◽  
Atlantic Cod ◽  
Management Strategies ◽  
Climatic Conditions ◽  
The North ◽  
Spawning Stock ◽  
The North Sea

The plight of the marine fisheries is attracting increasing attention as unsustainably high exploitation levels, exacerbated by more extreme climatic conditions, are driving stocks to the point of collapse. The North Atlantic cod ( Gadus morhua ), a species which until recently formed a major component of the demersal fisheries, has undergone significant declines across its range. The North Sea stock is typical of many, with a spawning stock biomass that has remained below the safe biological limit since 2000 and recruitment levels near the lowest on record. Cod within the North Sea are currently managed as a single stock, and yet mounting empirical evidence supports the existence of a metapopulation of regionally variable, genetically distinct, sub-stocks. Applying the same management strategies to multiple stocks that differ in their resilience to exploitation inevitably results in the overfishing and likely collapse of the weaker components. Indeed, recent studies have identified two North Sea spawning stocks that have undergone disproportionally large collapses with very substantial reductions in egg production. Similarly affected cod stocks in the northwest Atlantic have shown little evidence of recovery, despite fishery closures. The possible implications of ignoring sub-structuring within management units for biocomplexity, local adaptation and ecosystem stability are considered.

scholarly journals Genotyping of Two Mediterranean Trout Populations in Central-Southern Italy for Conservation Purposes Using a Rainbow-Trout-Derived SNP Array

Animals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1803
Author(s):  
Valentino Palombo ◽  
Elena De Zio ◽  
Giovanna Salvatore ◽  
Stefano Esposito ◽  
Nicolaia Iaffaldano ◽  
...  
Keyword(s):  
Rainbow Trout ◽  
Genetic Structure ◽  
Fishery Management ◽  
Snp Array ◽  
Fine Scale ◽  
Principal Coordinates Analysis ◽  
Data Set ◽  
Management Actions ◽  
Principal Coordinates ◽  
Mediterranean Trout

Mediterranean trout is a freshwater fish of particular interest with economic significance for fishery management, aquaculture and conservation biology. Unfortunately, native trout populations’ abundance is significantly threatened by anthropogenic disturbance. The introduction of commercial hatchery strains for recreation activities has compromised the genetic integrity status of native populations. This work assessed the fine-scale genetic structure of Mediterranean trout in the two main rivers of Molise region (Italy) to support conservation actions. In total, 288 specimens were caught in 28 different sites (14 per basins) and genotyped using the Affymetrix 57 K rainbow-trout-derived SNP array. Population differentiation was analyzed using pairwise weighted FST and overall F-statistic estimated by locus-by-locus analysis of molecular variance. Furthermore, an SNP data set was processed through principal coordinates analysis, discriminant analysis of principal components and admixture Bayesian clustering analysis. Firstly, our results demonstrated that rainbow trout SNP array can be successfully used for Mediterranean trout genotyping. In fact, despite an overwhelming number of loci that resulted as monomorphic in our populations, it must be emphasized that the resulted number of polymorphic loci (i.e., ~900 SNPs) has been sufficient to reveal a fine-scale genetic structure in the investigated populations, which is useful in supporting conservation and management actions. In particular, our findings allowed us to select candidate sites for the collection of adults, needed for the production of genetically pure juvenile trout, and sites to carry out the eradication of alien trout and successive re-introduction of native trout.

scholarly journals A simple clustering technique to extract subsets of data for function approximation

2015 ◽  
Vol 17 (5) ◽  
pp. 719-732
Author(s):  
Dulakshi Santhusitha Kumari Karunasingha ◽  
Shie-Yui Liong
Keyword(s):  
Function Approximation ◽  
Prediction Models ◽  
Data Extraction ◽  
Single Parameter ◽  
Subtractive Clustering ◽  
Data Sets ◽  
Clustering Methods ◽  
Clustering Method ◽  
Data Set ◽  
Functional Relationships

A simple clustering method is proposed for extracting representative subsets from lengthy data sets. The main purpose of the extracted subset of data is to use it to build prediction models (of the form of approximating functional relationships) instead of using the entire large data set. Such smaller subsets of data are often required in exploratory analysis stages of studies that involve resource consuming investigations. A few recent studies have used a subtractive clustering method (SCM) for such data extraction, in the absence of clustering methods for function approximation. SCM, however, requires several parameters to be specified. This study proposes a clustering method, which requires only a single parameter to be specified, yet it is shown to be as effective as the SCM. A method to find suitable values for the parameter is also proposed. Due to having only a single parameter, using the proposed clustering method is shown to be orders of magnitudes more efficient than using SCM. The effectiveness of the proposed method is demonstrated on phase space prediction of three univariate time series and prediction of two multivariate data sets. Some drawbacks of SCM when applied for data extraction are identified, and the proposed method is shown to be a solution for them.

scholarly journals Risk transfer beyond reinsurance: the added value of CAT bonds

2021 ◽  
Author(s):  
Tobias Götze ◽  
Marc Gürtler
Keyword(s):  
Risk Management ◽  
Default Risk ◽  
Management Strategies ◽  
Added Value ◽  
Insurance Companies ◽  
Data Set ◽  
Basis Risk ◽  
Cat Bonds ◽  
Risk Characteristics ◽  
Risk Management Strategies

AbstractReinsurance and CAT bonds are two alternative risk management instruments used by insurance companies. Insurers should be indifferent between the two instruments in a perfect capital market. However, the theoretical literature suggests that insured risk characteristics and market imperfections may influence the effectiveness and efficiency of reinsurance relative to CAT bonds. CAT bonds may add value to insurers’ risk management strategies and may therefore substitute for reinsurance. Our study is the first to empirically analyse if and under what circumstances CAT bonds can substitute for traditional reinsurance. Our analysis of a comprehensive data set comprising U.S. P&C insurers’ financial statements and CAT bond use shows that insurance companies’ choice of risk management instruments is not arbitrary. We find that the added value of CAT bonds mainly stems from non-indemnity bonds and reveal that (non-indemnity) CAT bonds are valuable under high reinsurer default risk, low basis risk and in high-risk layers.

scholarly journals Essential habitat for sardine juveniles in Iberian waters

2017 ◽  
Vol 81 (3) ◽  
pp. 351 ◽  
Author(s):  
Sílvia Rodríguez-Climent ◽  
Maria Manuel Angélico ◽  
Vítor Marques ◽  
Paulo Oliveira ◽  
Laura Wise ◽  
...  
Keyword(s):  
Fishery Management ◽  
Generalized Additive Models ◽  
Management Strategies ◽  
Coastal Region ◽  
Additive Models ◽  
Spawning Grounds ◽  
Significant Relationships ◽  
Juvenile Abundance ◽  
Spatial Differences ◽  
Core Areas

In a period when the Iberian sardine stock abundance is at its historical minimum, knowledge of the sardine juvenile’s distribution is crucial for the development of fishery management strategies. Generalized additive models were used to relate juvenile sardine presence with geographical variables and spawning grounds (egg abundance) and to model juvenile abundance with the concurrent environmental conditions. Three core areas of juvenile distribution were identified: the Northern Portuguese shelf (centred off Aveiro), the coastal region in the vicinity of the Tagus estuary, and the eastern Gulf of Cadiz. Spatial differences in the relationship between juvenile presence and egg abundances suggest that essential juvenile habitat might partially differ from the prevailing spawning grounds. Models also depicted significant relationships between juvenile abundance, temperature and geographical variables in combination with salinity in the west and with zooplankton in the south. Results indicate that the sardine juvenile distribution along the Iberian Peninsula waters are an outcome of a combination of dynamic processes occurring early in life, such as egg and larva retention, reduced mortality and favourable feeding grounds for both larvae and juveniles.

Volunteer potato interference in carrot

Weed Science ◽  
2006 ◽  
Vol 54 (1) ◽  
pp. 94-99 ◽  
Author(s):  
Martin M. Williams ◽  
Rick A. Boydston
Keyword(s):  
Weed Management ◽  
Yield Loss ◽  
Management Strategies ◽  
Field Studies ◽  
Functional Relationships ◽  
Weed Growth ◽  
Volunteer Potato ◽  
Tuber Production ◽  
Hand Weeding ◽  
Management Recommendations

Weed management systems in carrot are limited in part by a lack of fundamental understanding of crop–weed interactions. Irrigated field studies were conducted to quantify the effect of volunteer potato density and duration of interference on carrot yield and to determine relationships among weed density, duration of weed growth, and volunteer potato tuber production. A season-long volunteer potato density of 0.06 plants m−2produced from 150 to 230 g tubers m−2and resulted in an estimated 5% crop yield loss. At two volunteer potato plants m−2, the same level of crop loss was estimated with a duration of interference of 430 growing degree days (GDD), a time at which the weed had already produced 130 g tubers m−2. Volunteer potato height at the time of weed removal predicted carrot yield loss (R2= 0.77) and may be useful for timing of management strategies such as hand weeding. Functional relationships describing carrot–volunteer potato interactions provide simple information that is useful for developing weed management recommendations for carrot, a crop that relies on multiple tactics for managing weeds, and rotational crops that are negatively affected by persistence of volunteer potato.

Contemporary Management and Outcomes of Injuries to the Inferior Vena Cava: A Prospective Multicenter Trial From PROspective Observational Vascular Injury Treatment

2021 ◽  
pp. 000313482110385
Author(s):  
David P Stonko ◽  
Faris K. Azar ◽  
Richard D. Betzold ◽  
Jonathan J. Morrison ◽  
Ryan B. Fransman ◽  
...  
Keyword(s):  
Inferior Vena Cava ◽  
Vascular Injury ◽  
Inferior Vena ◽  
Management Strategies ◽  
Vena Cava ◽  
Multicenter Trial ◽  
Data Set ◽  
Injury Treatment ◽  
Contemporary Management ◽  
Injury Burden

Introduction Injuries to the inferior vena cava (IVC), while uncommon, have a high mortality despite modern advances. The goal of this study is to describe the diagnosis and management in the largest available prospective data set of vascular injuries across anatomic levels of IVC injury. Methods The American Association for the Surgery of Trauma PROspective Observational Vascular Injury Treatment (PROOVIT) registry was queried from November 2013 to January 2019. Demographics, diagnostic modalities, injury patterns, and management strategies were recorded and analyzed. Comparisons between anatomic levels were made using non-parametric Wilcoxon rank-sum statistics. Results 140 patients from 19 institutions were identified; median age was 30 years old (IQR 23-41), 75% were male, and 62% had penetrating mechanism. The suprarenal IVC group was associated with blunt mechanism (53% vs 32%, P = .02), had lower admission systolic blood pressure, pH, Glasgow Coma Scale (GCS), and higher ISS and thorax and abdomen AIS than the infrarenal injury group. Injuries were managed with open repair (70%) and ligation (30% overall; infrarenal 37% vs suprarenal 13%, P = .01). Endovascular therapy was used in 2% of cases. Overall mortality was 42% (infrarenal 33% vs suprarenal 66%, P<.001). Among survivors, there was no difference in first 24-hour PRBC transfusion requirement, or hospital or ICU length of stay. Conclusions Current PROOVIT registry data demonstrate continued use of ligation extending to the suprarenal IVC, limited adoption of endovascular management, and no dramatic increase in overall survival compared to previously published studies. Survival is likely related to IVC injury location and total injury burden.

Fish Stock Indicators as Measure for Sustainability

2015 ◽  
pp. 118-182 ◽  
Author(s):  
Violin S. Raykov ◽  
Ivelina Zlateva
Keyword(s):  
Black Sea ◽  
Fishery Management ◽  
Management Strategies ◽  
Age Determination ◽  
Reproductive Potential ◽  
Local Environment ◽  
Point Of View ◽  
The Black Sea ◽  
Fish Stock ◽  
Mortality Estimation

Particular species may be good indicators of specific environmental factors in their local environment. It was found that one of the main objectives for effective and sustainable management of the fish stocks is to make regular annual assessment of the parental stock biomass, length and weight growth, age determination, mortality estimation and reproductive potential estimation. The Black Sea sprat (Sprattus sprattus L.) is a key species in the Black Sea ecosystem. Small pelagic forage fish and especially local one with shared stocks are very important from ecological (key trophic level) and commercial (intensively exploited) point of view. Fishery management strategies must ensure that fishing mortality will not exceed that which corresponds to MSY, and that the biomass will not fall below a predefined threshold. The goal of the chapter is to define the main objectives and measures for sustainable sprat exploitation in order to be in favour of decision makers and fishery managers.

scholarly journals Development of a binational thyroid cancer clinical quality registry: a protocol paper

BMJ Open ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. e023723
Author(s):  
Liane J Ioannou ◽  
Jonathan Serpell ◽  
Joanne Dean ◽  
Cino Bendinelli ◽  
Jenny Gough ◽  
...  
Keyword(s):  
Thyroid Cancer ◽  
New Zealand ◽  
South Australia ◽  
Steering Committee ◽  
Population Based ◽  
Outcome Data ◽  
Term Outcome ◽  
Data Set ◽  
Clinical Quality ◽  
Quality Registry

IntroductionThe occurrence of thyroid cancer is increasing throughout the developed world and since the 1990s has become the fastest increasing malignancy. In 2014, a total of 2693 Australians and 302 New Zealanders were diagnosed with thyroid cancer, with this number projected to rise to 3650 in 2018. The purpose of this protocol is to establish a binational population-based clinical quality registry with the aim of monitoring and improving the quality of care provided to patients diagnosed with thyroid cancer in Australia and New Zealand.Methods and analysisThe Australian and New Zealand Thyroid Cancer Registry (ANZTCR) aims to capture clinical data for all patients over the age of 16 years with thyroid cancer, confirmed by histopathology report, who have been diagnosed, assessed or treated at a contributing hospital. A multidisciplinary steering committee was formed which, with operational support from Monash University, established the ANZTCR in early 2017. The pilot phase of the registry is currently operating in Victoria, New South Wales, Queensland, Western Australia and South Australia, with over 20 sites expected to come on board across Australia in 2018. A modified Delphi process was undertaken to determine the clinical quality indicators to be reported by the registry, and a minimum data set was developed comprising information regarding thyroid cancer diagnosis, pathology, surgery and 90-day follow-up.Future plansThe establishment of the ANZTCR provides the opportunity for Australia and New Zealand to further understand current practice in the treatment of thyroid cancer and identify variation in outcomes. The engagement of endocrine surgeons in supporting this initiative is crucial. While the pilot registry has a focus on early clinical outcomes, it is anticipated that future collection of longer term outcome data particularly for patients with poor prognostic disease will add significant further value to the registry.

An analysis of angler preferences for fishery management strategies

1985 ◽  
Vol 7 (3) ◽  
pp. 321-342 ◽  
Author(s):  
F. Andrew Schoolmaster ◽  
John W. Frazier
Keyword(s):  
Fishery Management ◽  
Management Strategies
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