Estimating fishing effort in small-scale fisheries using GPS tracking data and random forests

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.

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

PLoS ONE ◽

10.1371/journal.pone.0176862 ◽

2017 ◽

Vol 12 (5) ◽

pp. e0176862 ◽

Cited By ~ 20

Author(s):

Lauric Thiault ◽

Antoine Collin ◽

Frédérique Chlous ◽

Stefan Gelcich ◽

Joachim Claudet

Keyword(s):

Fishing Effort ◽

Small Scale ◽

Small Scale Fisheries

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

Frontiers in Marine Science ◽

10.3389/fmars.2021.707999 ◽

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.

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Fleet sizes, fishing effort and the ‘hidden’ factors behind statistics: An anthropological study of small-scale fisheries in UK

Marine Policy ◽

10.1016/j.marpol.2007.06.006 ◽

2008 ◽

Vol 32 (3) ◽

pp. 301-308 ◽

Cited By ~ 16

Author(s):

Yoshitaka Ota ◽

Roger Just

Keyword(s):

Fishing Effort ◽

Small Scale ◽

Small Scale Fisheries ◽

Anthropological Study

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Seasonal dynamics of small-scale fisheries in the Adriatic Sea

Mediterranean Marine Science ◽

10.12681/mms.2153 ◽

2018 ◽

Vol 19 (1) ◽

pp. 21 ◽

Cited By ~ 3

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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Using stakeholder’s perspectives of ‘Managed Access’ to guide management efforts in small-scale fisheries

Environmental Conservation ◽

10.1017/s0376892921000047 ◽

2021 ◽

pp. 1-10

Author(s):

Chad A Bowman ◽

Stephen C Mangi ◽

Hazel A Oxenford

Keyword(s):

Q Methodology ◽

Scientific Information ◽

Management Strategies ◽

Fishing Effort ◽

Small Scale ◽

Financial Investment ◽

Small Scale Fisheries ◽

Stakeholder Groups ◽

Systems Implementation ◽

Financial Investments

Summary Controlling and monitoring fishing effort and understanding human perspectives on fisheries management strategies are paramount to the successful management and sustainability of fisheries. Open-access fishing, which is commonplace in the small-scale fisheries (SSFs) of developing countries, poses severe challenges to management, and to address many of these challenges, Belize implemented a country-wide rights-based fishery (RBF) management strategy known as Managed Access (MA). This study uses Q methodology to explore the perspectives of four key stakeholder groups on the early impacts of the strategy, revealing five distinct perspectives. Perspective 1 supported MA but believed some components needed revision. Perspective 2 had high confidence in MA and expected improvements with financial investments. Perspective 3 did not believe in the strategy and expressed frustration with it not protecting fishers’ rights. Perspective 4 captured the biological concerns not addressed by the strategy, while Perspective 5 focused on the strategy’s inability to make the fisheries more profitable thus far. The different perspectives indicate that MA will be unlikely to meet its objectives without more financial investment in enforcement and stakeholder engagement, research and the strengthening of institutional capacity. This study contributes to the scarce scientific information on the early stages of RBF systems implementation in SSFs.

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Aquatic Wildmeat Consumption of Guiana Dolphins (Sotalia guianensis) in Lake Maracaibo System, Venezuela

Frontiers in Marine Science ◽

10.3389/fmars.2021.625801 ◽

2021 ◽

Vol 8 ◽

Author(s):

Yurasi Briceño ◽

Leonardo Sánchez ◽

Fernando Trujillo ◽

Lorenzo von Fersen ◽

Sonsireé Ramírez

Keyword(s):

Negative Impact ◽

Capture Rate ◽

Fishing Effort ◽

Small Scale ◽

Structured Interviews ◽

Small Scale Fisheries ◽

Sotalia Guianensis ◽

Lake Maracaibo ◽

High Incidence ◽

Guiana Dolphin

In many regions of the world, the use of cetaceans as bait or protein source has been reported. In most cases the individuals are from bycatch but also from intentionally killed animals. Cetaceans with coastal habits are more susceptible to negative interactions with small-scale fisheries, as in the case of the Guiana dolphin (Sotalia guianensis) in the Lake Maracaibo system. For decades, the use of Guiana dolphins by local communities has been reported in this region and is culturally supported by recipes for its preparation. Most of these data was outdated and some were anecdotal, so the objective of this work was to collect systematically data through surveys using the snowball method in seven artisanal fishing communities and to try to quantify the capture rate and to inquire about the potential impact of this practice on the population of Guiana dolphin. From 2017 to 2019, 95 semi-structured interviews were applied. An average bycatch of 180 individuals/year was obtained, the highest catch rate in the entire geographic distribution, an alarming situation considering that the surveys were not carried out in all the fishing ports, generating an underestimation. A total of 78% of interviewed recognized at least one bycatch event during their fishing effort. Surveys revealed a higher incidence of entanglement of offspring and juveniles (78%). 77% of the respondents deny the sale and commercialization of the species, while 5% mention some type of trade. The most frequent part exploited was the dorsal muscle, confirmed by fishermen (97%, n = 72) and the rest of the animal is discarded. During this investigation three episodes of directed capture were recorded, affecting a total of 23 individuals, two of them were pregnant females. The interviews also revealed that the majority of fishermen (93%) recognize the capture of this species as illegal. Considering the vulnerability of the Guiana dolphin in the country, the high incidence of capture and consumption and the lack of surveillance and sanctions by government entities, it is imperative to immediate actions to mitigate the negative impact on the population.

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Interactions of small-scale fisheries in Mexico’s northwest Pacific

Latin American Journal of Aquatic Research ◽

10.3856/vol48-issue1-fulltext-2176 ◽

2020 ◽

Vol 48 (1) ◽

pp. 94-105

Author(s):

Francisco Javier Mendoza-Portillo ◽

Mauricio Ramírez-Rodríguez ◽

Víctor Vargas-López

Keyword(s):

Temporal Distribution ◽

Fishing Effort ◽

Small Scale ◽

Northwestern Pacific ◽

Northwest Pacific ◽

Temporal Complexity ◽

Small Scale Fisheries ◽

Management Perspective ◽

Pen Shell ◽

Management Schemes

In Mexico, as in other parts of the world, there is limited knowledge regarding the operation of small-scale fisheries. Also, there is an urgent need for the diversity of fisheries and their interactions, and the diversity of species to be analyzed on a regional level. In this study, the dynamics of the small-scale fleet operating in San Ignacio in the northwestern Pacific of the state of Baja California Sur were analyzed, recognizing the fishery’s multi-species and multi-gear character and its effect on the spatial and temporal distribution of the fishing effort. The operative units (OU) approach was applied; OUs are defined as the set of associated vessels that exploit one or more target species using similar fishing gears. The information about species, gears, sites and fishing seasons was obtained from interviews with 74 fishers. The OUs identified included: diving-pen shell scallop; diving-squalid callista; diving-Pismo clam; collection-black ark; trap-barred sand bass; trap-crab; trap-lobster; cast net-shrimp; bottom net-fish; surface net-fish; bottom net-shark. The variation in the activity of each OU is related to the availability of the resources, prices of the products and official restrictions. From a management perspective, this method helps to clarify which OUs adhere to specific rules associated with their métier and others, which are less well defined since their OU characteristics are associated with their fishery level. The definition and characterization of the OU, based on the local knowledge of the fishermen, assist the design of management schemes that consider the spatial and temporal complexity of the small-scale fisheries.

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

Royal Society Open Science ◽

10.1098/rsos.200621 ◽

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.

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A Cloud Computing Architecture to Map Trawling Activities Using Positioning Data

Volume 9: 15th IEEE/ASME International Conference on Mechatronic and Embedded Systems and Applications ◽

10.1115/detc2019-97779 ◽

2019 ◽

Author(s):

A. Galdelli ◽

A. Mancini ◽

A. N. Tassetti ◽

C. Ferrà Vega ◽

E. Armelloni ◽

...

Keyword(s):

Integrated Management ◽

Low Cost ◽

Sustainable Use ◽

Fishing Effort ◽

Small Scale ◽

Automatic Identification ◽

Identification System ◽

Small Vessels ◽

Small Scale Fisheries ◽

Major Development

Abstract Descriptive and spatially-explicit information on fisheries plays a key role for an efficient integrated management of the maritime activities and the sustainable use of marine resources. However, this information is today still hard to obtain and, consequently, is a major issue for implementing Marine Spatial Planning (MSP). Since 2002, the Automatic Identification System (AIS) has been undergoing a major development allowing now for a real time geo-tracking and identification of equipped vessels of more than 15m in length overall (LOA) and, if properly processed, for the production of adequate information for MSP. Such monitoring systems or other low-cost and low-burden solutions are still missing for small vessels (LOA < 12m), whose catches and fishing effort remain spatially unassessed and, hence, unregulated. In this context, we propose an architecture to process vessel tracking data, understand the behaviour of trawling fleets and map related fishing activities. It could be used to process not only AIS data but also positioning data from other low cost systems as IoT sensors that share their position over LoRa and 2G/3G/4G links. Analysis gives back important and verified data (overall accuracy of 92% for trawlers) and opens up development perspectives for monitoring small scale fisheries, helping hence to fill fishery data gaps and obtain a clearer picture of the fishing grounds as a whole.

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