Innovations in Fishing Gear Design Aiming at the Sustainable Use of Commercial Fish Stocks

2006 ◽  
Author(s):  
Erdmann Dahm
Keyword(s):  
Fishery Management ◽  
Sustainable Use ◽  
Mesh Size ◽  
Fish Stock ◽  
Fishing Gear ◽  
Commercial Fish ◽  
Fish Stocks ◽  
Gear Design ◽  
Ecological Changes ◽  
Open Shape

The present status of some of the fish stocks in North Sea and Baltic shows them to be outside safe biological limits. Reasons for this lie partly in hydrographic and ecological changes not in favour for a constant supply of fresh recruits to the fishery every year. On the other hand, fishery has its share in the observed downward trend by growth overfishing and reducing the size and number of possible spawners. The only mean available for the fishery management to restore a fish stock composed of several year classes is to apply technical measures as e.g.closures in space and time or fishing gear regulations. The breakdown of the historical measure “mesh size regulation in diamond mesh trawls” due to technological progress has created a wave of worldwide research. It has focused on trawl codends where the meshes are held artificially in their most open shape or by introducing into the trawl metal structures able to separate small from big fish or fish from crayfish. A parallel development of a scientifically objective mesh measuring instrument will help to enforce the new regulations. However, longer use of some of the new designs has revealed some deficiencies. Other innovative designs or the concept of certified codends will hopefully ensure the permanently better selectivity of contemporary trawl codends.

How to Make Individual Transferable Quotas Work Economically, Socially, and Environmentally

2018 ◽  
Author(s):  
Rashid Sumaila
Keyword(s):  
Fisheries Management ◽  
Sustainable Use ◽  
Fish Stock ◽  
Open Market ◽  
Economic Returns ◽  
Total Allowable Catch ◽  
Fish Stocks ◽  
Individual Transferable Quotas ◽  
Management Objectives ◽  
Ecosystem Based Fisheries Management

The economic tool of individual transferable quotas (ITQs) gives their owners exclusive and transferable rights to catch a given portion of the total allowable catch (TAC) of a given fish stock. Authorities establish TACs and then divide them among individual fishers or firms in the form of individual catch quotas, usually a percentage of the TAC. ITQs are transferable through selling and buying in an open market. The main arguments by proponents of ITQs is that they eliminate the need to “race for the fish” and thus increase economic returns while eliminating overcapacity and overfishing. In general, fisheries’ management objectives consist of ecological (sustainable use of fish stocks), economic (no economic waste), and social (mainly the equitable distribution of fisheries benefits) issues. There is evidence to show that ITQs do indeed reduce economic waste and increase profits for those remaining in fisheries. However, they do not perform well in terms of sustainability or socially. A proposal that integrates ITQs in a comprehensive and effective ecosystem-based fisheries management system that is more likely to perform much better than ITQs with respect to ecological, economic, and social objectives is presented in this article.

scholarly journals Length-Based Stock Assessment of Smith's Barb, Puntioplites proctozystron (Bleeker, 1865) (Cyprinidae) and Asian Redtail Catfish, Hemibagrus nemurus, (Valenciennes, 1840), (Bagridae) in a Multipurpose Reservoir in Thailand

2021 ◽  
Vol 34 (2) ◽  
Author(s):  
KAJITPAN CHARERNNATE ◽  
PAVAROT NORANARTTRAGOON ◽  
TUANTONG JUTAGATE ◽  
Keyword(s):  
Growth Parameters ◽  
Stock Assessment ◽  
Relative Yield ◽  
Mesh Size ◽  
Fish Stock ◽  
Fish Stocks ◽  
The Status ◽  
Curvature Parameter ◽  
Spawning Potential Ratio ◽  
Fish Stock Assessment

Catches from inland fisheries in Thailand are about 200,000 tonnes annually and plays an important role in food security and subsidiary income. However, fish stocks are seldom assessed because of the lack of catch and effort data. In this study, two fish stock assessment models, viz., relative yield per recruit and length-based spawning potential ratio, were used to evaluate the status of two species as well as to highlight their applications to datalimited situation in Thailand. The study was conducted at Kangkrajan Reservoir, Thailand, for two targeted species, viz., Smith's barb, Puntioplites proctozystron (Bleeker, 1865) and Asian redtail catfish, Hemibagrus nemurus (Valenciennes, 1840) using length frequency data. The data were collected throughout 2019. Both species showed isometric growth. Von Bertalanffy growth parameters were estimated. Asymptotic length, curvature parameter and theoretical age at length zero were 36.2 cm TL, 0.39 yr-1 and -0.28 yr for P. proctozystron, respectively, and 63.2 cm TL, 0.37 yr-1 and -0.32 yr for H. nemurus. The exploitation rates reveal that both species are slightly overfished. Sizes at 50 % maturity and 50 % selectivities were 17.8 and 23.5 cm TL for P. proctozystron, respectively, and 15.6 and 20.8 cm TL for H. nemurus. Considering both parameters, the size at first capture to sustain the fisheries of P. proctozystron and H. nemurus should be >18 cm and >30 cm, respectively, which can be achieved by mesh-size regulations.

scholarly journals Modelling of white bream (Blicca bjoerkna (Linnaeus, 1758)) commercial catches by different parameters of fishing gillnets in Kyiv Reservoir

2021 ◽  
pp. 5-17
Author(s):  
V. Lytvynenko ◽  
◽  
G. Kotovska ◽  
O. Buzevych ◽  
S. Kurhanskyi ◽  
...  
Keyword(s):  
Sustainable Use ◽  
Age Groups ◽  
Mesh Size ◽  
Commercial Fish ◽  
Weight Growth ◽  
Effective Removal ◽  
Proposed Model ◽  
The Mathematical Model ◽  
First Time ◽  
White Bream

Purpose. To analyze the existing experience in quantitative and qualitative modelling of commercial fish harvesting and to develop the methodological approaches in determining the optimal catch parameters for gillnets. Methodology. An adjusted annual commercial mortality rate was used to determine the catches composition in gillnets with different mesh sizes. Findings. The proposed model was developed within the framework of the generally accepted concept of population dynamics and biomass as a result of mortality and weight growth. It showed the dependence of the size-age structure and total weight of the catch on the mesh size of the grids. Originality of the work was caused by using the mathematical model that can ensure sustainable use of nature based on the optimal parameters of shutter grids on the possibility of their effective removal of certain age groups of white bream for the first time. Practical Value: calculations performed according to this model for the white bream of the Kyiv Reservoir showed that it is optimal to use grids with a mesh step of 40-50 mm, which allow to obtain the maximum catch per unit of replenishment and ensure high population fertility. Keywords: white bream (Blicca bjoerkna Linnaeus, 1758), Kyiv reservoir, commercial catches, modelling of catch.

Managing fish stocks under climate uncertainty

2005 ◽  
Vol 62 (7) ◽  
pp. 1531-1541 ◽  
Author(s):  
Brian J. Rothschild ◽  
Changsheng Chen ◽  
R. Greg Lough
Keyword(s):  
Decision Theory ◽  
Fishery Management ◽  
Causal Chain ◽  
The State ◽  
Population Characteristics ◽  
Fish Stock ◽  
Fish Stocks ◽  
Formal Framework ◽  
Past Data ◽  
State Of The Environment

Abstract The quantitative evaluation of the management of fish stocks under uncertainty requires a formal framework. Decision theory provides that framework. Application of decision theory to fishery management requires information about both the fish stock and the state of the environment. Using Georges Bank haddock as a case study, it is possible to determine the probability of good or poor recruitment using past data and a constant environment. Understanding the state of the environment is more difficult, however, because fixed levels of recruitment, in particular, are associated with different population characteristics, which drastically reduce the sample size for any particular recruitment–environment scenario. Decision theory challenges us to improve our capability of predicting the state of nature, and it appears that this can be accomplished best by reducing the length of the causal chain, a goal now made feasible by the availability of high-resolution, high-frequency ocean models.

scholarly journals STUDI DESAIN DAN KOMPOSISI JENIS HASIL TANGKAPAN ALAT TANGKAP TRAP NET DI PERAIRAN KECAMATAN SIGERI KABUPATEN PANGKEP

2019 ◽  
Vol 2 (1) ◽  
pp. 86-99
Author(s):  
Mustamin Tajuddin ◽  
Ihsan H.Cotte ◽  
Asmidar Asmidar
Keyword(s):  
Coastal Waters ◽  
Sustainable Use ◽  
Secondary Data ◽  
Mesh Size ◽  
Economic Feasibility ◽  
Fishing Ground ◽  
Fishing Gear ◽  
Environmental Friendliness ◽  
Coastal Fisheries ◽  
Fisheries Resources

The research is entitled Utilization of coastal fisheries resources with trap net fishingequipment in the waters of Pangkep Regency. Related to that, the community uses thepotential of fish resources in the coastal waters of Pangkep Regency with a variety offishing gear, one of which is trap net (local read: tiku). Objectives are: 1) Knowing thecomposition of the type of trap net caught operated in coastal waters; 2) Knowing thelevel of environmental friendliness of the trap net fishing equipment operated in coastalwaters 3) Knowing the economic feasibility of trap net fishing equipment operated in thecoastal waters of Pangkep Regency. This research is expected to provide constructorsregarding the composition of catches in the use of Coastal Fishing Ground resourceswith net trap fishing equipment in the waters of Pangkep Regency, South Sulawesi toensure access to sustainable use of fisheries resources. The study was conducted in June -December 2018 in the coastal waters of Sigeri District, Pangkep Regency. Materials andtools related directly or indirectly to research to make measurements and observations inthe field. The data needed consists of pruimer and secondary data. To achieve the goal,the data collected is carried out by analyzing fishing gear designs and analyzing thecomposition of catch species.The design of the trap net fishing gear is rectangular with avery small mesh size and the material is made of nylon (waring). The size of the trap netis 500 meters long and 1.5 meters wide. The composition of the types of trap net catchesoperated in the coastal waters of Pangkep Regency is very large and in general, fish thatmigrate daily at low tide take place.

Use and abuse of fishery models

2001 ◽  
Vol 58 (1) ◽  
pp. 10-17 ◽  
Author(s):  
Jon T Schnute ◽  
Laura J Richards
Keyword(s):  
World Literature ◽  
Fishery Management ◽  
Stock Assessment ◽  
Management Practice ◽  
Fish Stock ◽  
Fish Stocks ◽  
Creative Thought ◽  
Modeling Process ◽  
Stock Biomass ◽  
Fish Stock Assessment

Recent failures of important fish stocks give mathematical models a poor reputation as tools for fishery management. This paper examines the role of models in fish stock assessment and identifies reasons why they can fail. Starting with laws of arithmetic, models attempt to relate observed data to unknown quantities, such as the stock biomass and abundance. Typically, the number of unknowns greatly exceeds the number of observations, and models must impose hypothetical constraints to give useful estimates. We use the word "fishmetic" (rhymes with arithmetic) to represent uncertainty in the conversion of arithmetic to practical fishery models. Arbitrary assumptions cannot be avoided, even though different choices can greatly influence the outcome of the analysis. We compare the modeling process in fisheries with that in other sciences. World literature also offers useful analogies. Potential reasons for failure suggest possible improvements to the application of fishery models. We recommend that modelers remain skeptical, expand their knowledge base, apply common sense, and implement robust strategies for fishery management. Particularly creative thought must be applied to the problem of translating scientific knowledge into management practice. Comparisons between fish stocks and financial stocks illustrate some possibilities.

scholarly journals KEBIJAKAN DAN STRATEGI PENGELOLAAN PERIKANAN TANGKAP DI DANAU TOBA PASKA INTRODUKSI IKAN BILIH

2017 ◽  
Vol 3 (1) ◽  
pp. 1
Author(s):  
Sonny Koeshendrajana
Keyword(s):  
Fishery Management ◽  
Positive Impact ◽  
Management Practice ◽  
Fishing Effort ◽  
Survey Method ◽  
Fish Stock ◽  
Fishing Gear ◽  
Management Options ◽  
Rapid Appraisal ◽  
Descriptive Method

Pengelolaan perikanan tangkap pada hakekatnya adalah pengendalian penangkapan (control of fishing) dan pengendalian upaya penangkapan (control of fishing effort) melalui sejumlah opsi pengelolaan yang diimplementasikan oleh pihak pengelola (management authority). Kajian kebijakan dan strategi pengelolaan perikanan tangkap di perairan Danau Toba pasca introduksi ikan bilih (Mystacoleucus padangensis Bleeker) dimaksudkan untuk memberikan panduan praktek pengelolaan yang mampu menjamin keberlanjutan perikanan ikan bilih di perairan Danau Toba. Metode survei penilaian cepat (rapid appraisal survey) dan review literatur digunakan dalam kajian ini; sedangkan metode analisis deskriptif tabulatif dan content analysis digunakan untuk membantu pengambilan kesimpulan. Hasil kajian menunjukkan bahwa ikan bilih yang ditebarkan ke Danau Toba 2.840 ekor dengan ukuran panjang berkisar antara4,1-5,7 cm dan bobot 0,9-1,5 g pada tahun 2003 telah mampu memberikan dampak positif secara ekonomi dan sosial bagi masyarakat sekitar Danau Toba. Penggunaan alat tangkap yang kurang ataupun tidak terkontrol telah memberikan indikasi penurunan jumlah dan kualitas stok ikan bilih; sehingga implementasi opsi pengelolaan yang meliputi pengembangan kawasan konservasi dan pengaturan serta pengendalian penggunaan alat tangkap bagan untuk menjamin keberlanjutan perikanan ikan bilih perlu segera diterapkan oleh pihak pengelola.Fishery management is essentially a control of fishing and fishing effort through various management options implemented by a management authority. Studies on policies and strategies for fishery management in the Lake Toba water body post introducing or stocking of bilih fish (Mystacoleucus padangensis Bleeker)aimed at providing a sort of guidelines for management practice in order to ensure sustainability of such the fishery. Rapid appraisal survey method and literature review were used in this study. Analysis of the study used a descriptive method compounded by cross tabulated data techniques and a content anaysis method. Results show that introducing of bilih fish in the Toba Lake amounted of 2,840 piece with body length of 4.1-5.7 cm and body weight of 0.9-1.5 g in 2003 has been able to provide a positive impact to social and economic aspects of the society surrounding the Lake Toba. However, the use of uncontrolled fishing and fishing effort was led to indication of decreasing quantitatively and qualitatively such of the fish stock; therefore, implementation of management options of developing a protected or conserved area and controlled the use of bagan fishing gear has to be imposed by management authority.

CRITICAL FACTORS OF WATER CONTENT FOR FISH STOCKS IN THE WATER RESERVOIRS OF KAZAKHSTAN

2017 ◽  
pp. 9-18
Author(s):  
Saule Zhangirovna Asylbekova ◽  
Kuanysh Baibulatovich Isbekov ◽  
Evgeniy Vyacheslavovich Kulikov
Keyword(s):  
Water Content ◽  
Water Level ◽  
Water Availability ◽  
Hydrological Regime ◽  
Fishing Effort ◽  
Water Reservoirs ◽  
The Caspian Sea ◽  
Annual Fish ◽  
Commercial Fish ◽  
Fish Stocks

The hydrological regime of water reservoirs in different years has a decisive impact on the abundance of commercial fish stocks and the quality of ichthyocenoses. In this connection in 2015-2016 there was conducted a retrospective analysis and ranking of hydrological regime impact on these factors. The paper gives evaluation of catches and fish stocks under different scenarios of water availability in the main fishing ponds of the Republic of Kazakhstan that give about 80% of the annual fish catch of the country (except the Caspian Sea). There were analyzed 2000 factors of hydrological regime (water level, annual discharge) and 1845 factors of fishing stocks (catches, abundance, fish biomass). The paper determines the critical characteristics of water availability for fish stocks. There have been proposed a number of administrative decisions and actions in case if water content would approach to the critical level. Among them: limitation of fish catches in the following year; widening zones restricted for fishing; intensification of safety measures of the fish young in residual ponds during arid periods; introduction of catch standards for a unit of fishing effort in low-water years, high-water years and years with normal water level in rivers.

Long-term changes in fish pond management as ‘an unplanned ecosystem experiment’: importance of zooplankton structure, nutrients and light for species composition of cyanobacterial blooms

1995 ◽  
Vol 32 (4) ◽  
pp. 187-196 ◽  
Author(s):  
L. Pechar
Keyword(s):  
Species Composition ◽  
Fishery Management ◽  
Grazing Pressure ◽  
Organic Fertilizers ◽  
Cyanobacterial Blooms ◽  
Fish Stock ◽  
Fish Ponds ◽  
Single Filament ◽  
The 1950S ◽  
Water Blooms

The study presents data on the species composition of cyanobacterial water blooms in Czech fish ponds from the 1950s to the 1990s. Since the 1950s, a shift from large-colonial Aphanizomenon flos-aquae var. flos-aquae through Microcystis aeruginosa and small-colonial species of Anabaena to single-filament species (Planktohrix agardhii, Limnothrix redekei, Aphanizomenon gracile) or single-cell forms (Microcystis ichtyoblabe), has been observed. The changes in the species composition of the water blooms are closely related to changes in fishery management (increase in fish stock, increase in application of organic fertilizers). At present the high predation of fish upon zooplankton results in elimination of large colonial blooms of A. flos-aquae associated with large filtering zooplankton (Daphnia). Low grazing pressure of zooplankton, low light conditions and low N:P ratios are suitable conditions for mass development of the small species of cyanobacteria. High pH is not necessary to achieve cyanobacteria dominance.

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