scholarly journals NATURAL-ANTHROPOGENIC REGIMES IN SIMPLE MODELS OF THE GLOBAL MARINE FISHERIES

2019 ◽  
Vol 3 (1) ◽  
pp. 210-222
Author(s):  
Alexander Ryzhenkov
Keyword(s):  
Marine Fish ◽  
Feedback Loop ◽  
Maximum Sustainable Yield ◽  
Fish Stock ◽  
Sustainable Yield ◽  
Marine Fisheries ◽  
The World ◽  
Key Variables ◽  
Time Frames ◽  
Dynamics Method

The study applies the system dynamics method in upgrading the World Bank’s global marine fisheries models in the interest of achieving the UN goals of sustainable development. The key variables are a global marine fish stock, its natural growth, as well as the fisheries’ effort and catch. The equations for the reproduction of the fish stock in the regimes of maximum sustainable yield, overfishing or undercatch are derived. Determined are collapse time frames in result of typical overfishing varieties. A new positive feedback loop has been proposed in regulating global marine fish stock to ensure maximum sustainable yield asymptotically.

scholarly journals Towards an integrated forecasting system for fisheries on habitat-bound stocks

Ocean Science ◽  
2013 ◽  
Vol 9 (2) ◽  
pp. 261-279 ◽  
Author(s):  
A. Christensen ◽  
M. Butenschön ◽  
Z. Gürkan ◽  
I. J. Allen
Keyword(s):  
Climatic Variability ◽  
Maximum Sustainable Yield ◽  
Ecosystem Dynamics ◽  
Fish Stock ◽  
Generic Model ◽  
Sustainable Yield ◽  
Model Framework ◽  
The North ◽  
Basin Scale ◽  
Forecasting System

Abstract. First results of a coupled modelling and forecasting system for fisheries on habitat-bound stocks are being presented. The system consists currently of three mathematically, fundamentally different model subsystems coupled offline: POLCOMS providing the physical environment implemented in the domain of the north-west European shelf, the SPAM model which describes sandeel stocks in the North Sea, and the third component, the SLAM model, which connects POLCOMS and SPAM by computing the physical–biological interaction. Our major experience by the coupling model subsystems is that well-defined and generic model interfaces are very important for a successful and extendable coupled model framework. The integrated approach, simulating ecosystem dynamics from physics to fish, allows for analysis of the pathways in the ecosystem to investigate the propagation of changes in the ocean climate and to quantify the impacts on the higher trophic level, in this case the sandeel population, demonstrated here on the basis of hindcast data. The coupled forecasting system is tested for some typical scientific questions appearing in spatial fish stock management and marine spatial planning, including determination of local and basin-scale maximum sustainable yield, stock connectivity and source/sink structure. Our presented simulations indicate that sandeel stocks are currently exploited close to the maximum sustainable yield, even though periodic overfishing seems to have occurred, but large uncertainty is associated with determining stock maximum sustainable yield due to stock inherent dynamics and climatic variability. Our statistical ensemble simulations indicates that the predictive horizon set by climate interannual variability is 2–6 yr, after which only an asymptotic probability distribution of stock properties, like biomass, are predictable.

Management of evolving fish stocks

1998 ◽  
Vol 55 (8) ◽  
pp. 1971-1982 ◽  
Author(s):  
Mikko Heino
Keyword(s):  
Maximum Sustainable Yield ◽  
Evolutionary Change ◽  
Fish Stock ◽  
Sustainable Yield ◽  
Harvest Rate ◽  
Fish Stocks ◽  
Population Dynamics Model ◽  
Before And After ◽  
Age Structured ◽  
Delayed Maturation

Mortality caused by harvesting can select for life history changes in the harvested stock. Should this possibility be taken into account in the management of renewable resources? I compare the performance of different harvest strategies when evolutionary change is accounted for with the help of an age-structured population dynamics model. Assuming that age of first reproduction is the only evolving trait, harvesting of only mature individuals selects for delayed maturation and results in increased sustainable yields. Unselective harvesting of both mature and immature fish selects for earlier maturation which causes the sustainable yield to decrease. Constant stock size and constant harvest rate strategies perform equally well in terms of maximum sustainable yield, both before and after evolutionary change. The maximum sustainable yield for fixed-quota strategies is lower. All those strategies have similar evolutionary consequences given a similar average harvest rate. Coevolutionary dynamics between fish stock and the stock manager indicate that the evolutionary benefits of selective harvesting are attainable without incurring yield losses in the near future.

scholarly journals Effective fisheries management instrumental in improving fish stock status

2020 ◽  
Vol 117 (4) ◽  
pp. 2218-2224 ◽  
Author(s):  
Ray Hilborn ◽  
Ricardo Oscar Amoroso ◽  
Christopher M. Anderson ◽  
Julia K. Baum ◽  
Trevor A. Branch ◽  
...  
Keyword(s):  
Fisheries Management ◽  
Marine Fish ◽  
Food System ◽  
Fish Stock ◽  
Management Tools ◽  
Fish Stocks ◽  
Fisheries Science ◽  
The World ◽  
Fish Catch ◽  
Intensively Managed

Marine fish stocks are an important part of the world food system and are particularly important for many of the poorest people of the world. Most existing analyses suggest overfishing is increasing, and there is widespread concern that fish stocks are decreasing throughout most of the world. We assembled trends in abundance and harvest rate of stocks that are scientifically assessed, constituting half of the reported global marine fish catch. For these stocks, on average, abundance is increasing and is at proposed target levels. Compared with regions that are intensively managed, regions with less-developed fisheries management have, on average, 3-fold greater harvest rates and half the abundance as assessed stocks. Available evidence suggests that the regions without assessments of abundance have little fisheries management, and stocks are in poor shape. Increased application of area-appropriate fisheries science recommendations and management tools are still needed for sustaining fisheries in places where they are lacking.

scholarly journals MAXIMUM SUSTAINABLE YIELD OF TRAWL FISHERY ALONG THE SOUTH-WEST COAST OF INDIA: BAYESIAN ESTIMATION APPROACH

2020 ◽  
Vol 67 (1) ◽  
Author(s):  
T. V. Sathianandan ◽  
Somy Kuriakose ◽  
K. G. Mini ◽  
P. K. Safeena
Keyword(s):  
Bayesian Estimation ◽  
Marine Fish ◽  
West Coast ◽  
Fishing Effort ◽  
Maximum Sustainable Yield ◽  
Sustainable Yield ◽  
The South ◽  
Trawl Fishery ◽  
South West ◽  
South West Coast

The south-west region of the Indian coast is shared by three maritime states and it contributes nearly 32% to the total marine fish production of the country. Mechanised trawl fishery accounts for 44% of the marine fish harvest in the south-west coast and a number of resources are harvested by trawl nets from this region. An assessment of the trawl fishery to determine sustainable harvest levels for mechanised trawlers in the region was carried out using time series data on annual landings and fishing effort of mechanised trawlers during the period 1990-2015. A Bayesian estimation method for Schaefer model was used for the analysis. Posterior probability densities of parameters of the model, maximum sustainable yield (MSY) and corresponding biomass were obtained through Bayesian estimation for the trawl fishery in south-west coast and the harvest levels were found to be above MSY from 2012 onwards. Forecasts of biomass and fish landings by mechanised trawlers upto 2025 under different levels of fishing effort were also simulated using the model to study the dynamic changes over time. It was found that the numbers of multiday trawlers and single day trawlers operating in this region have to be reduced by 207 and 36 respectively to retain the harvest at sustainable level.

scholarly journals POTENTIAL PRODUCTION OF DEMERSAL FISH STOCK IN THE MALACCA STRAIT OF INDONESIA

2015 ◽  
Vol 21 (1) ◽  
pp. 45 ◽  
Author(s):  
Purwanto Purwanto
Keyword(s):  
Demersal Fish ◽  
Fishing Effort ◽  
Maximum Sustainable Yield ◽  
Fish Stock ◽  
Sustainable Yield ◽  
Optimum Level ◽  
Fish Production ◽  
Potential Production ◽  
Malacca Strait

Malacca Strait is one of the main fishing areas for demersal fishery in Indonesia. To support the management of that fishery, an assessment of the demersal fish stock was conducted. This study estimated that the maximum sustainable yield and the optimal catch per unit effortof demersal fishery in the Malacca Strait were about 106.8 thousand tons/year and 28.5 tons per unit of Danish seine, respectively, resulting from the operation of 3,752 Danish seines. Unfortunately, fishing effort was higher than its optimum level and the fish stock was over-exploited since 2003. To recover the demersal fish stock to its optimum level and to ensure the optimal fish production from demersal fishery in the Malacca Strait, it was necessary to reduce fishing effort at about 67% from its level in 2011.

Legal Status of Maximum Sustainable Yield Concept in International Fisheries Law and Its Adoption in the Marine Fisheries Regime of Bangladesh: A Critical Analysis

2017 ◽  
Vol 32 (3) ◽  
pp. 544-569 ◽  
Author(s):  
Abdullah Al Arif
Keyword(s):  
Fisheries Management ◽  
Legal Status ◽  
Marine Ecosystem ◽  
Maximum Sustainable Yield ◽  
Sustainable Yield ◽  
Marine Fisheries ◽  
Policy Regime ◽  
Management Policies ◽  
Fisheries Law ◽  
International Fisheries

Abstract Maximum sustainable yield, popularly known by its acronym msy, is perhaps the most disputed concept in the realm of international fisheries law. The first part of this article briefly describes the genesis, development and subsequent adoption of the msy concept in international, regional and national fisheries management instruments. The second part documents the criticisms that the msy concept has generated to date and seeks to find out the legal status of the msy concept in international fisheries law. The third part of this article critically examines the adoption of the msy concept in the legal and policy regime for marine fisheries in Bangladesh. The article argues that more rigorous provisions for conservation of marine ecosystem should be incorporated in fisheries management policies of Bangladesh instead of solely relying on the msy concept as an objective of fisheries management.

scholarly journals Maximum Sustainable Yield and Development Status of 24 Commercial Marine Fish Groups from Pakistani Waters

2020 ◽  
Vol 53 (1) ◽  
Author(s):  
Kui Zhang ◽  
Ping Geng ◽  
Sher Khan Panhwar ◽  
Khadim Hussain Memon ◽  
Zuozhi Chen
Keyword(s):  
Marine Fish ◽  
Maximum Sustainable Yield ◽  
Sustainable Yield ◽  
Development Status

scholarly journals Maximum sustainable yield, maximum economic yield and sustainability in fisheries

2020 ◽  
Vol 9 (1) ◽  
pp. 15-17
Author(s):  
Ernesto A Chávez
Keyword(s):  
Fisheries Management ◽  
Age Structure ◽  
Stock Assessment ◽  
Fishing Effort ◽  
Maximum Sustainable Yield ◽  
Fish Stock ◽  
Sustainable Yield ◽  
Fishing Mortality ◽  
Maximum Economic Yield ◽  
Fish Stock Assessment

A brief review of the concept of Maximum Sustainable Yield (MSY) used in fisheries management is discussed. The convenience of assessing the exploited stocks with the aid of simulation is advised, because implies the possibility to analyze the age structure of the fishery in more detail, as compared to the traditional methods of fish stock assessment. Emphasis is given to the use of the MSY as limit reference point because as long as the Fishing Mortality or fishing effort required for that point is kept at lower values, the fishery will have a good chance to be sustainable. A mention of the Maximum Economic Yield is made, proposing its use a target for the management, because it is reached in general with lower F values then that for the MSY, and this way keeping the fishery in a healthy condition.

scholarly journals Estimating maximum sustainable yield of snow crab (Chionoecetes opilio) off Tohoku Japan via a state-space assessment model with time-varying natural mortality

2020 ◽  
Author(s):  
Yasutoki Shibata ◽  
Jiro Nagao ◽  
Yoji Narimatsu ◽  
Eisuke Morikawa ◽  
Yuto Suzuki ◽  
...  
Keyword(s):  
State Space ◽  
Maximum Sustainable Yield ◽  
Biological Characteristics ◽  
Assessment Model ◽  
Fish Stock ◽  
Snow Crab ◽  
Sustainable Yield ◽  
Natural Mortality ◽  
Time Varying ◽  
Chionoecetes Opilio

AbstractYield from fisheries is a tangible benefit of ecosystem services and sustaining or restoring a fish stock level to achieve a maximum sustainable yield (MSY). Snow crab (Chionoecetes opilio) off Tohoku has been managed by a total allowable catch since 1996, although their abundance has not increased even after 2011, when fishing pressure rapidly decreased because of the Great East Japan Earthquake. This implies that their biological characteristics, such as recruits, natural mortality coefficient (M), and terminal molting probabilities (p), might have changed. We developed “just another state-space stock assessment model (JASAM)” to estimate the MSY of the snow crab off Tohoku, Japan, considering interannual variations in M and p. The multi-model inference revealed that M increased from 0.2 in 1997 to 0.59 in 2018, although it was not different among the instars, sex, nor terminal molt of crabs. The parameter p also increased by 1.34–2.46 times depending on the instar growth stages from 1997 to 2018. We estimated the MSYs in three scenarios, which drastically changed if M and p were set as they were in the past or at the current values estimated from this study. This result indicated that the MSY of snow crab would also be time-varying based on their time-varying biological characteristics.

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