scholarly journals Risk tolerance and control perception in a game-theoretic bioeconomic model for small-scale fisheries

2020 ◽  
Vol 7 (7) ◽  
pp. 200621
Author(s):  
Eric Zettermann Dias de Azevedo ◽  
David Valença Dantas ◽  
Fábio G. Daura-Jorge
Keyword(s):  
Evolutionary Game ◽  
Fishing Effort ◽  
Risk Tolerance ◽  
Sensitivity Analyses ◽  
Small Scale ◽  
Individual Level ◽  
Small Scale Fisheries ◽  
Game Theoretic ◽  
And Control ◽  
Two Populations

Cooperation is generally the most advantageous strategy for the group; however, on an individual level, cheating is frequently more attractive. In a fishery, one can choose to cooperate by fishing only the regulated amount or not to cooperate, by fishing to maximize profits. Top-down management can help to emulate a cooperative result in fisheries, but it is costly and not always a viable alternative for development states. Here, we investigate elements of a fishing system that can be strategically managed to encourage a cooperative behaviour. Using bioeconomic data, we modelled an evolutionary game between two populations of fishers that differ if they cooperate or do not cooperate with a fishing restriction. We penalized players including risk tolerance and control perception, two social parameters that might favour cooperation. We assessed the degrees to which risk tolerance and control perception affect the cooperative behaviours of fishers in a restricted fishing effort small-scale fishery (RSSF) in southern Brazil. We also assessed the likelihood of a scenario wherein a cooperative strategy can evolve and dominate the system. We identified dominance and coexistence outcomes for the RSSF. Sensitivity analyses suggested that both control perception and risk tolerance could facilitate a cooperative outcome for the fishery.

scholarly journals Technical measures without enforcement tools: is there any sense? A methodological approach for the estimation of passive net length in small scale fisheries

2014 ◽  
Vol 16 (1) ◽  
pp. 82 ◽  
Author(s):  
A. LUCCHETTI ◽  
G. BUGLIONI ◽  
A. CONIDES ◽  
D. KLAOUDATOS ◽  
P. SARTOR ◽  
...  
Keyword(s):  
Methodological Approach ◽  
Fishing Effort ◽  
Management Tool ◽  
Small Scale ◽  
Strongly Correlated ◽  
Small Scale Fisheries ◽  
Length Estimation ◽  
Fishing Gears ◽  
And Control ◽  
Technical Measures

Passive nets are currently among the most important fishing gears largely used along the Mediterranean coasts by the small scale fisheries sector. The fishing effort exerted by this sector is strongly correlated with net dimensions. Therefore, the use of passive nets is worldwide managed by defining net length and net drop. The EC Reg. 1967/2006 reports that the length of bottom-set and drifting nets may be also defined considering their weight or volume; however, no practical suggestions for fisheries inspectors are yet available. Consequently,  even if such technical measures are reasonable from a theoretical viewpoint, they are hardly suitable as a management tool, due to the difficulties in harbour control. The overall objective of this paper is to provide a quick methodological approach for the gross estimation of passive net length (by net type) on the basis of net volume. The final goal is to support fisheries managers with suitable advice for enforcement and control purposes. The results obtained are important for the management of the fishing effort exerted by small scale fisheries. The methodology developed in this study should be considered as a first attempt to tackle the tangled problem of net length estimation that can be easily applied in other fisheries and areas in order to improve the precision of the models developed herein.

scholarly journals Competition between static gear of the small-scale fisheries in Algarve waters (southern Portugal)

2010 ◽  
Vol 11 (2) ◽  
pp. 225 ◽  
Author(s):  
K. ERZINI ◽  
J.M.S. GONCALVES ◽  
L. BENTES ◽  
P.G. LINO ◽  
J. RIBEIRO ◽  
...  
Keyword(s):  
Species Composition ◽  
Fishing Effort ◽  
Small Scale ◽  
Gill Nets ◽  
Scarce Resources ◽  
Small Scale Fisheries ◽  
Southern Portugal ◽  
Catch Rates ◽  
One Year ◽  
And Control

Parallel fishing trials with 0.30 mm diameter monofilament gill nets and longlines using small hooks were carried out in the Algarve (southern Portugal) over a one-year period, 1997-1998, with the objective of comparing species composition, catch rates, discards and size ranges. Four hook sizes of 'Mustad' brand, round bent, flatted sea hooks (numbers 15, 13, 12 and 11) and four mesh sizes of 25, 30, 35 and 40 mm (nominal bar length) of gill nets were used in the trials. Overall, 84 species were caught, with gill nets taking 71 species and longlines 54 species and with 41 species caught by both gears. The amount of discarding was higher for gill nets than for longlines. The catch species composition differed between the two gears, with the commercially valuable sea breams dominating the longline catches whereas small pelagics were relatively more important in the gill nets. Multivariate analysis showed a clear separation between the different sizes of the two gears both in terms of numbers and weights per species. Algarve gill netters and longliners fish the same species assemblage on the same fishing grounds, but have clearly different impacts in terms of catch species composition, catch rates and sizes. This information will be useful for the improved management of these small-scale, multi-species, multi-gear fisheries, where different gears compete for scarce resources. In particular this study provides a basis for a more rational allocation of licenses and control of fishing effort.

scholarly journals A Bio-Economic Analysis of the Liberian Coastal Fisheries

2020 ◽  
Vol 12 (23) ◽  
pp. 9848
Author(s):  
Alvin Slewion Jueseah ◽  
Dadi Mar Kristofersson ◽  
Tumi Tómasson ◽  
Ogmundur Knutsson
Keyword(s):  
New Technologies ◽  
Fishing Effort ◽  
Small Scale ◽  
Exclusion Zone ◽  
Coastal Fisheries ◽  
Small Scale Fisheries ◽  
Species Complexes ◽  
Limited Enforcement ◽  
Dugout Canoes ◽  
The Government

Many coastal fisheries are subject to harvesting externalities due to inadequate regulations compounded by limited enforcement. Coastal fisheries in Liberia consist of a fleet of dugout canoes (Kru) primarily targeting demersal finfish, larger open wooden boats propelled with outboard engines targeting small inshore pelagics (Fanti), and a small number of industrial trawlers employing midwater and bottom trawls targeting finfish and shrimp. This paper develops a bio-economic model for the coastal fisheries in Liberia and employs the model to identify economic optimal fishing effort and harvesting trajectories for the different coastal fleets. The results show under harvesting and disinvestments in the coastal fisheries in Liberia. In 2010 the Government of Liberia declared a six nautical mile inshore exclusion zone accessible only to small-scale fisheries (SSF), which was accompanied by increased enforcement. The coastal fleets in 2016 were profitable but the distribution of profits was tilted to the small-scale fleets. The government needs to evaluate what policy options are available to fully utilize the fisheries potential for different species complexes while at the same time reduce the risk of conflict and overharvesting. There appears to be a need for investment in new technologies, which can only take place if fishing in Liberia will remain profitable.

scholarly journals Combining participatory and socioeconomic approaches to map fishing effort in small-scale fisheries

PLoS ONE ◽  
2017 ◽  
Vol 12 (5) ◽  
pp. e0176862 ◽  
Author(s):  
Lauric Thiault ◽  
Antoine Collin ◽  
Frédérique Chlous ◽  
Stefan Gelcich ◽  
Joachim Claudet
Keyword(s):  
Fishing Effort ◽  
Small Scale ◽  
Small Scale Fisheries

scholarly journals Evolutionary game theory for physical and biological scientists. I. Training and validating population dynamics equations

2014 ◽  
Vol 4 (4) ◽  
pp. 20140037 ◽  
Author(s):  
David Liao ◽  
Thea D. Tlsty
Keyword(s):  
Game Theory ◽  
Population Dynamics ◽  
Evolutionary Game Theory ◽  
Evolutionary Dynamics ◽  
Evolutionary Game ◽  
Treatment Strategies ◽  
Analysis Method ◽  
Analysis Techniques ◽  
Game Theoretic ◽  
And Control

Failure to understand evolutionary dynamics has been hypothesized as limiting our ability to control biological systems. An increasing awareness of similarities between macroscopic ecosystems and cellular tissues has inspired optimism that game theory will provide insights into the progression and control of cancer. To realize this potential, the ability to compare game theoretic models and experimental measurements of population dynamics should be broadly disseminated. In this tutorial, we present an analysis method that can be used to train parameters in game theoretic dynamics equations, used to validate the resulting equations, and used to make predictions to challenge these equations and to design treatment strategies. The data analysis techniques in this tutorial are adapted from the analysis of reaction kinetics using the method of initial rates taught in undergraduate general chemistry courses. Reliance on computer programming is avoided to encourage the adoption of these methods as routine bench activities.

scholarly journals Fishing Effort and Associated Catch per Unit Effort for Small-Scale Fisheries in the Mozambique Channel Region: 1950–2016

2021 ◽  
Vol 8 ◽  
Author(s):  
Dirk Zeller ◽  
Gabriel M. S. Vianna ◽  
Matthew Ansell ◽  
Angie Coulter ◽  
Brittany Derrick ◽  
...  
Keyword(s):  
Fishing Effort ◽  
Small Scale ◽  
Catch Per Unit Effort ◽  
Important Species ◽  
Small Scale Fisheries ◽  
Mozambique Channel ◽  
Fishing Vessels ◽  
Unit Effort ◽  
Fishing Capacity ◽  
Channel Region

The Mozambique Channel region in East Africa has diverse marine ecosystems and serves as a migratory corridor for economically important species. Local and foreign industrial fisheries operate in the Mozambique Channel, but regional small-scale fisheries are the crucially important fisheries that provide food security, livelihoods, and economic opportunities for rural coastal communities. This study reconstructed and investigated trends in the fishing effort and catch per unit effort (CPUE) of small-scale marine fisheries in four Exclusive Economic Zones (EEZ) that constitute the Mozambique Channel, i.e., Union of Comoros, Madagascar, Mayotte, and Mozambique, from 1950 to 2016. Effective fishing effort for small-scale fisheries in the form of fishing capacity in kWdays (i.e., kilowatt days) was derived using the number, length, motorization (engine power) by fishing vessels, as well as an approximate human-powered equivalent for shore-based fishers without vessels, as well as days of fishing per year. Effective small-scale fishing effort in the Mozambique Channel increased by nearly 60 times from just over 386,000 kWdays in 1950 to over 23 million kWdays in 2016. Correspondingly, the overall small-scale CPUE, based on previously and independently reconstructed catch data declined by 91% in the region as a whole, from just under 175 kg⋅kWday–1 in the early 1950s to just over 15 kg⋅kWday–1 in recent years. All four EEZs showed the strongest declines in the small-scale CPUE in the earlier decades, driven by motorization and growth in vessel numbers impacting effective fishing effort. Increased motorization combined with a substantial growth in overall vessel numbers were the drivers of the increasing fishing effort and decreasing CPUE, and clearly suggest that continuing to increase the fishing capacity of small-scale fisheries in the absence of effective and restrictive management actions may exacerbate overexploitation risk.

Coordination and Party Change in the United States

2020 ◽  
Vol 48 (6) ◽  
pp. 807-821
Author(s):  
Daniel J. Lee ◽  
Michael Brady
Keyword(s):  
Political Parties ◽  
Evolutionary Game ◽  
Party Systems ◽  
The United States ◽  
Party Change ◽  
Individual Level ◽  
Monolithic Group ◽  
Party Control ◽  
Game Theoretic ◽  
Micro Level

The ability of American political parties to change issue positions is potentially hindered by problems of coordination. Research on parties since the 1990s has shown what tools party leadership can use to enforce discipline and cohesion among its ranks. We, however, question whether those theories of party control, which explain party stability, can straightforwardly explain party change. Oftentimes we think of parties strategically altering issue positions, but what is “the party?” Rather than a monolithic group, American parties are relatively decentralized, weak, and individualistic compared with other party systems. We present an evolutionary game theoretic example to illustrate the problem of coordination in party change. This theoretical framework suggests an empirical focus on individual-level behaviors to better understand the dynamics of party change. We analyze roll call voting of members of Congress on the environment and abortion to illustrate micro-level behaviors suggested by our theoretical discussion.

scholarly journals Seasonal dynamics of small-scale fisheries in the Adriatic Sea

2018 ◽  
Vol 19 (1) ◽  
pp. 21 ◽  
Author(s):  
FABIO GRATI ◽  
ADMIR ALADZUZ ◽  
ERNESTO AZZURRO ◽  
LUCA BOLOGNINI ◽  
PIERLUIGI CARBONARA ◽  
...  
Keyword(s):  
Seasonal Dynamics ◽  
Adriatic Sea ◽  
Economic Value ◽  
Fishing Effort ◽  
Small Scale ◽  
Target Species ◽  
Frequency Distributions ◽  
Small Scale Fisheries ◽  
Blue Growth ◽  
Physical And Chemical

The main aim of the present study is to increase the knowledge on the seasonal dynamics of the set gears used by Adriatic small-scale fisheries (SSFs) through the collation of data (landings, fishing effort, composition of catches, length-frequency distributions of target species and economic value of landings) on target species,. The study focused on the three set gears mainly used in the basin: gillnets, trammel nets and traps. The results confirmed that SSFs are diverse, complex and dynamic, representing an economic and social engine and providing seafood and employment to local economies. In the Adriatic Sea, SSFs exploit coastal fishing grounds where the seasonal fluctuations of the physical and chemical parameters of the water column strongly influence the occurrence of the different species. Because of this, many different types of set gears are currently used to catch a pool of target species over the year. Fishermen use more than one set gear during the year and tend to increase the fishing effort when the target species concentrate inside the coastal areas during the recruitment or the spawning season. Accordingly, landings reached the highest values during such periods and often include a large portion of juveniles and/or spawners. The study highlighted that the lack of appropriate data and complete statistics is still one of the main constraints for most of the Adriatic coastal countries, as few countries have in place routinely monitoring programs while others are dealing mostly with estimates. These gaps often have the effect of marginalizing and undervaluing the real role of SSFs in a Blue Growth process.

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