scholarly journals Analysis of Optimal Harvest and Management of Capture Fishery of Lake Ziway, Central Ethiopia

2021 ◽  
Author(s):  
Kindineh Sisay
Keyword(s):  
Public Good ◽  
Fish Species ◽  
Fishery Management ◽  
Management Practices ◽  
Stock Assessment ◽  
Free Access ◽  
Fishing Gear ◽  
Total Allowable Catch ◽  
Individual Transferable Quotas ◽  
Near Future

Abstract Even if there is fluctuation in fish species diversity and relative abundance of the species, Lake Ziway provides numerous environmental and/or ecosystem services. Despite to its importance, the Lake faces numerous threats because of its public good characteristics. Following the exponentially increased demand for fishes and the resource being public good, magnificent number of individuals are participated in capture fisheries in order to secure their livelihood. Free access to the fisheries, illegal fishing gears and environmental degradation are among the main reasons of decline in fish species and degradation of the Lake. From the current stock assessment survey, the study showed decline in biomass of fish over time. These negative trends in the Lake Ziway fisheries and poor water quality led to loss of livelihoods of many households who are directly or indirectly dependent on the Lake. Therefore, management of Lake Ziway fishery becomes very essential to manage the resource efficiently in a way that maximize fishers present and future benefits otherwise, the fish resource will disappear in the near future. Concerning management practices, most of the fishery regulations in this Lake put emphasis on the restriction of fishing gear, but the application of this instrument with its restrictions is almost zero. Moreover, Individual Transferable Quotas (ITQs) foster greater transparency and accountability for the management and enhancement of fishery resources by quota owners. In this regard, since it generates a sense of ownership and its versatility in providing a stable and productive market, ITQs are more effective than gear restrictions and in fact, it has major social benefits by controlling overharvesting. Due to this, to ensure the nutritional and food security of the country currently and in the near future, there is a need to enforce fishing gear restriction and set ITQs. Furthermore, there must be strong effort on studying the current stock of fish, and numbers of legal and illegal fishers to set Individual Transferable Quotas (ITQs) and Total Allowable Catch (TAC) for sustainable fishery management of Lake Ziway.

scholarly journals Ecological Reference Points for Atlantic Menhaden Established Using an Ecosystem Model of Intermediate Complexity

2020 ◽  
Vol 7 ◽  
Author(s):  
David Chagaris ◽  
Katie Drew ◽  
Amy Schueller ◽  
Matt Cieri ◽  
Joana Brito ◽  
...  
Keyword(s):  
Striped Bass ◽  
Fishery Management ◽  
Stock Assessment ◽  
Reference Points ◽  
Atlantic Menhaden ◽  
Assessment Model ◽  
Total Allowable Catch ◽  
Important Species ◽  
Ecosystem Impacts ◽  
Intermediate Complexity

Atlantic menhaden (Brevoortia tyrannus) are an important forage fish for many predators, and they also support the largest commercial fishery by weight on the U.S. East Coast. Menhaden management has been working toward ecological reference points (ERPs) that account for menhaden’s role in the ecosystem. The goal of this work was to develop menhaden ERPs using ecosystem models. An existing Ecopath with Ecosim model of the Northwest Atlantic Continental Shelf (NWACS) was reduced in complexity from 61 to 17 species/functional groups. The new NWACS model of intermediate complexity for ecosystems (NWACS-MICE) serves to link the dynamics of menhaden with key managed predators. Striped bass (Morone saxatilis) were determined to be most sensitive to menhaden harvest and therefore served as an indicator of ecosystem impacts. ERPs were based on the tradeoff relationship between the equilibrium biomass of striped bass and menhaden fishing mortality (F). The ERPs were defined as the menhaden F rates that maintain striped bass at their biomass target and threshold when striped bass are fished at their Ftarget, and all other modeled species were fished at status quo levels. These correspond to an ERP Ftarget of 0.19 and an ERP Fthreshold of 0.57, which are lower than the single species reference points by 30–40%, but higher than current (2017) menhaden F. The ERPs were then fed back into the age-structured stock assessment model projections to provide information on total allowable catch. The ERPs developed in this study were adopted by the Atlantic menhaden Management Board, marking a shift toward ecosystem-based fishery management for this economically and ecologically important species.

scholarly journals Individual Transferable Quotas (ITQ), Rebuilding Fisheries and Short-Termism: How Biased Reasoning Impacts Management

Systems ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 7
Author(s):  
Edward J. Garrity
Keyword(s):  
Fishery Management ◽  
Geographic Region ◽  
Total Allowable Catch ◽  
Financial Transfers ◽  
Fish Stocks ◽  
Individual Transferable Quotas ◽  
Individual Transferable Quota ◽  
Short Termism ◽  
Human Component ◽  
Pilot Tests

Recent research on global fisheries has reconfirmed a 2006 study that suggested global fisheries would collapse by 2048 if fisheries were not better managed and trends reversed. While many researchers have endorsed rights-based fishery management as a key ingredient for successful management and rebuilding fisheries, in practice the results are mixed and success varies by geographic region. Rights-based approaches such as individual transferable quota (ITQ) provide a necessary help to the important task of rebuilding fisheries, but we assert that they are sometimes less effective due to the human component of the system. Specifically, we examine the issue of setting an appropriate total allowable catch (TAC) in Individual Transferable Quota (ITQ) systems. ITQ are designed on the premise that economic ownership is sufficient incentive to entice fishers to be stewards of the resource. However, an excessive short-term orientation and an affective risk response by fishers can overwhelm feelings of ownership. In such cases, fishers and fishing communities can exert sufficient pressure on TAC setting and reduce the effectiveness of ITQ fisheries toward rebuilding fish stocks. Based on our analysis that draws on cognitive psychology, short-termism, and affective risk, we suggest heightened and wider democratic involvement by stakeholders in co-managed ITQ fisheries along with potential pilot tests of government-assisted financial transfers to help in transitioning ITQ fisheries to sustainable states.

Trade-offs in fishery management objectives when allowing catch limit carry-over between years

2020 ◽  
Author(s):  
John R Wiedenmann ◽  
Daniel S Holland
Keyword(s):  
Life Histories ◽  
Fishery Management ◽  
Risk Measures ◽  
Stock Assessment ◽  
Total Allowable Catch ◽  
Management Objectives ◽  
Strategy Evaluation ◽  
Trade Offs ◽  
Stock Biomass ◽  
Carry Over

Abstract Fisheries managed with explicit annual catch limits often have realized catches below the total allowable catch. Carry-over provisions allowing aggregate or individual carry-forward of catch underages are included in many fishery management systems, but the ramifications of these provisions on different fishery management objectives such as average catch, variability in catch, and probability and degree of overfishing are not well understood. We developed a management strategy evaluation simulation to explore performance of alternative carry-over policies assuming different life histories and under different causes of catch underages. We evaluated the impacts of the carry-overs across common management objectives to understand the trade-offs associated with different amounts of allowable carry-over. We find that carry-overs can increase yield to the fishery but can also increase the risks of overfishing, low stock biomass, low catch, and the interannual variability in catch. All of these risk measures increase with the amount of carry-over allowed in most cases, but for cases of low stock productivity or positively biased stock assessment estimates, larger carry-over allowances resulted in similar or lower yield compared to smaller allowances. The analysis suggests that some benefits of carry-over can be maintained and risks can be limited by restricting the maximum carry-over allowed.

Reflections on technology and science in fishery research

2017 ◽  
Vol 74 (8) ◽  
pp. 2069-2075 ◽  
Author(s):  
David N. MacLennan
Keyword(s):  
Fishery Management ◽  
Assessment Tool ◽  
Stock Assessment ◽  
Commercial Fishing ◽  
Fishing Gear ◽  
Positive Contribution ◽  
Personal Involvement ◽  
The Past ◽  
Fishery Research ◽  
The 1960S

Abstract In the latter part of the 20th century, fishery research expanded from its original biological base to include new areas, notably investigations of fishing-gear performance and fish-detection by sonar. The past 50 years have seen huge advances in technology and the combination of physical and biological insights in fishery research. Fishing-gear investigations initially focussed on the economics of commercial fishing, but in the 1970s energy consumption in fishing became a major issue. Thereafter, the objectives changed to support for fishery management through gear innovations and research, giving a better understanding of exploitation patterns. During this period, fishery acoustics advanced from crude beginnings in the 1960s to the powerful stock-assessment tool it is today. Progress in these fields has depended on multi-disciplinary research involving both the physical and biological sciences. There have been failures along the way, but there is now good understanding of how technology as well as science can make a positive contribution to fishery management. This essay describes these developments as seen from my personal involvement over the past half century. It concludes with some pointers to the future, and practical advice to young researchers considering a career in fishery research.

Reduce Disease Burden of Human Schistosomiasis in Asia Through Biological Control

2020 ◽  
Vol 20 (12) ◽  
pp. 1118-1132
Author(s):  
Sidra Saleem ◽  
Haroon Ahmed ◽  
Tooba Siddiqui ◽  
Seyma Gunyakti Kilinc ◽  
Aisha Khan ◽  
...  
Keyword(s):  
Biological Control ◽  
Geographical Distribution ◽  
Disease Burden ◽  
Management Practices ◽  
Control Strategies ◽  
Parasitic Disease ◽  
Asian Countries ◽  
Neglected Disease ◽  
Current Review ◽  
Near Future

Schistosomiasis is a chronic parasitic disease caused by a trematode blood fluke of the genus Schistosoma that belongs to the Schistosomatidae family. It is a neglected disease in different regions of Asia. In this review, 218 articles (between 2000 and 2017) related to the topic were collected from PubMed and Google scholar and reviewed. After thoroughly reading collected articles, due to irrelevant topic requirements, 94 articles were excluded. Articles that have data associated with Asian regions are considered. In Asia, the disease is prevalent in China, Philippines, Indonesia, Yemen, Nepal and Laos, etc. While in Pakistan, India and Bangladesh, the disease is not endemic and very few cases were reported. The disease was eliminated from Japan and Iran. The current review highlights the geographical distribution among Asian countries, transmission patterns, diagnosis, control strategies based on the use of anthelmintic plants and management practices implemented in Asia for the control of schistosomiasis. However, new implementations to treat schistosomiasis in humans should be proved to eliminate the disease finally in the future. This review emphasizes the biological control of schistosomiasis for the eradication of the disease from Asia in the near future.

scholarly journals Flexibility of joint production in mixed fisheries and implications for management

2021 ◽  
Author(s):  
Florence Briton ◽  
Olivier Thébaud ◽  
Claire Macher ◽  
Caleb Gardner ◽  
Lorne Richard Little
Keyword(s):  
Economic Performance ◽  
Economic Incentives ◽  
Joint Production ◽  
Total Allowable Catch ◽  
Individual Transferable Quotas ◽  
The Past ◽  
Different Types ◽  
Commercial Species ◽  
Management Recommendations ◽  
Production Problems

Abstract Over the past decade, efforts have been made to factor technical interactions into management recommendations for mixed fisheries. Yet, the dynamics underlying joint production in mixed fisheries are generally poorly captured in operational mixed fisheries models supporting total allowable catch advice. Using an integrated ecological–economic simulation model, we explore the extent to which fishers are likely to alter the species composition of their landings in a mixed fishery managed with individual transferable quotas, the Australian Southern and Eastern Scalefish and Shark Fishery. Our simulations capture three different types of joint production problems, highlighting the flexibility that exists in terms of achievable catch compositions when quota markets provide the economic incentives to adapt fishing practices to quota availability. These results highlight the importance of capturing the drivers of fishing choices when advising TAC decisions in mixed fisheries. We also identify a hierarchy of species in this fishery, with harvest targets set for primary commercial species determining most of its socio-economic performance.

Results of fisheries research of the Shaturskaya group of lakes

Fisheries ◽  
2021 ◽  
Vol 2021 (1) ◽  
pp. 52-60
Author(s):  
Andrey Bykov
Keyword(s):  
Species Composition ◽  
Fish Species ◽  
Thermal Regime ◽  
Seasonal Migration ◽  
Fishing Gear ◽  
Invasive Fish ◽  
Cooling Reservoir ◽  
Quantitative Indicators

Based on the results of comprehensive fisheries research, a brief description of the ecosystem of the lake of the Shaturskaya group operated in the mode of the cooling reservoir of the Shaturskaya GRES is given. The features of the thermal regime of the Shatursky lakes in the zone of the circulating flow of cooled waters are considered. A brief description of the species composition and quantitative indicators of the development of phytoplankton, zooplankton and macrozoobenthos communities is given. The structure of fish catches in the lakes depending on the fishing gear used is considered according to the data of accounting surveys with set nets and fry drag. The process of formation of the ichthyofauna of Shatursky lakes, characteristic of natural and man-made ecosystems of reservoirs-coolers of energy facilities, is shown. The occurrence of native and invasive fish species in catches is described, and the mechanism of seasonal migration of fish depending on the temperature and oxygen regimes of the Shatursky lakes is considered.

Lessons learned from data-limited evaluations of data-rich reef fish species in the Gulf of Mexico: implications for providing fisheries management advice for data-poor stocks

2019 ◽  
Vol 76 (9) ◽  
pp. 1624-1639 ◽  
Author(s):  
Skyler R. Sagarese ◽  
William J. Harford ◽  
John F. Walter ◽  
Meaghan D. Bryan ◽  
J. Jeffery Isely ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Reef Fish ◽  
Fish Species ◽  
Stock Assessment ◽  
Lessons Learned ◽  
Management Objectives ◽  
Trade Offs ◽  
Data Limitations ◽  
Management Procedures ◽  
Reef Fish Species

Specifying annual catch limits for artisanal fisheries, low economic value stocks, or bycatch species is problematic due to data limitations. Many empirical management procedures (MPs) have been developed that provide catch advice based on achieving a stable catch or a historical target (i.e., instead of maximum sustainable yield). However, a thorough comparison of derived yield streams between empirical MPs and stock assessment models has not been explored. We first evaluate trade-offs in conservation and yield metrics for data-limited approaches through management strategy evaluation (MSE) of seven data-rich reef fish species in the Gulf of Mexico. We then apply data-limited approaches for each species and compare how catch advice differs from current age-based assessment models. MSEs identified empirical MPs (e.g., using relative abundance) as a compromise between data requirements and the ability to consistently achieve management objectives (e.g., prevent overfishing). Catch advice differed greatly among data-limited approaches and current assessments, likely due to data inputs and assumptions. Adaptive MPs become clearly viable options that can achieve management objectives while incorporating auxiliary data beyond catch-only approaches.

scholarly journals Assessment of biowaste losses through unsound waste management practices in rural areas and the role of home composting

2016 ◽  
Author(s):  
Florin Constantin MIHAI
Keyword(s):  
Waste Management ◽  
Rural Areas ◽  
Management Practices ◽  
Sustainable Rural Development ◽  
Greenhouse Gasses ◽  
Waste Management Practices ◽  
Near Future ◽  
Home Composting ◽  
Management Issues

The paper examines the biowaste management issues across rural areas ofRomania in the context of poor waste management infrastructure in the lastdecade (2003-2012). Biowaste is the main fraction of municipal waste, thusa proper management is a key challenge in order to sustain a bioeconomy inthe near future. The amount of biowaste generated and uncollected by wasteoperators is generally uncontrolled disposed if not recovered through homecomposting. The paper points out the role of home composting in divertingthe biowaste from wild dumps and landfills for the regions covered or notby waste collection services. Home composting and the biowaste losses arefurther assessed based on several scenarios (worse-case, pessimistic,realistic, optimistic) where the net loads of greenhouse gasses (GHG) arecalculated at national and regional levels. The transition of homecomposting techniques, from open piles to plastic bins with respect tostandard guidelines will improve the home composting performance in termsof compost quality and net GHG’s savings, supporting a bio-based economywhich will lead towards a sustainable rural development. Regionaldisparities are revealed across Romanian counties and the paper opens newresearch perspectives regarding which options should be adopted by countiesand rural municipalities in the biowaste management process.

scholarly journals Length and Weight Relationships for 31 Species of Fishes Caught by Trawl Off the Arabian Sea Coast of Oman

2008 ◽  
Vol 13 ◽  
pp. 43
Author(s):  
Brett A. Human ◽  
Haithem Al-Busaidi
Keyword(s):  
Fish Species ◽  
Arabian Sea ◽  
Stock Assessment ◽  
Fork Length ◽  
Biological Parameters ◽  
Conversion Factors ◽  
Weight Measurement ◽  
Total Length ◽  
Commercial Species ◽  
Sea Coast

Length and weight measurement for 31f ish species encountered in the Arabian Sea , o f f t h e Oma n Coast, were collected by demersal trawling during March 2007 and March 2008. A total of 3,261 specimens were measured for total length, or fork length, where appropriate, and green weight. Several commonly caught commercial species undergo onboard processing (dressing) prior to packaging, and dressed weight to green weight regressions and conversion factors were calculated for 12 of these species. The relationships obtained in this study were compared with those of other  studies for the same fish species. These data are fundamental to understanding the biological parameters of fishes, and can be applied to fisheries stock assessment and management models. 

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