Shifting gears: Diversification, intensification, and effort increases in small-scale fisheries (1950-2010)

Selgrath, Jennifer C.; Gergel, Sarah E.; Vincent, Amanda C. J.

doi:10.1371/journal.pone.0190232

Cited by 36 publications

(29 citation statements)

References 64 publications

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“…When participatory maps of human practices are paired with maps of natural systems, their union can be used to delineate sustainable activities from those that are damaging. In the Danajon Bank, participatory mapping revealed that fishing effort increased more than 1800%, and that this increase was due to the growing number of individuals fishing, rather than to changes in individual fishing effort [5,24]. In contrast, non-spatial measures greatly underestimated the severity of this change.…”

Section: Discussionmentioning

confidence: 99%

“…Communities in the region maintain a high reliance on marine resources and fishing is a primary livelihood. Fishers employ diverse fishing practices, enabling them to catch a diverse range of marine life [24]. Most fishers use outrigger canoe style boats.…”

Section: Study Sitementioning

confidence: 99%

“…Thus, the minimum sample size that we identified was 2.2% of the population of male fishers from the communities that we engaged in this study, or 1.1% of the total number of male fishers in the survey area. Since the Danajon Bank is crowded and supports an incredibly high diversity of fishing methods [24], we expect that the 1.1% minimum sample size was influenced by the significant amount of spatial overlap in the fishing grounds used by individuals and communities. Our mapping results suggest that a larger number of individuals may be needed to reach an asymptote in 1980 than in later years.…”

Section: How Much Is Enough?mentioning

confidence: 99%

“…In many cases, spatial data-obtained through participatory mapping-is essential for accurately tracking change, because non-spatial data may severely underestimate impacts. In Danajon Bank fisheries, for example, non-spatial data (total effort by all fishers) estimated a 250% increase in fishing effort (1960-2010) [5,24]. However, spatially explicit fishing effort (mean fishing effort in all grid cells)-documented through participatory mapping-identified that fishing effort increased 1800% .…”

Section: Essential Role Of Mapsmentioning

confidence: 99%

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How Much is Enough? Improving Participatory Mapping Using Area Rarefaction Curves

Selgrath

Gergel

2019

Land

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Participatory mapping is a valuable approach for documenting the influence of human activities on species, ecosystems, and ecosystem services, as well as the variability of human activities over space and time. This method is particularly valuable in data-poor systems; however, there has never been a systematic approach for identifying the total number of respondents necessary to map the entire spatial extent of a particular human activity. Here, we develop a new technique for identifying sufficient respondent sample sizes for participatory mapping by adapting species rarefaction curves. With a case study from a heavily fished marine ecosystem in the central Philippines, we analyze participatory maps depicting locations of individuals’ fishing grounds across six decades. Within a specified area, we assessed how different sample sizes (i.e. small vs. large numbers of respondents) would influence the estimated extent of fishing for a specified area. The estimated extent of fishing demonstrated asymptotic behavior as after interviewing a sufficiently large number of individuals, additional respondents did not increase the estimated extent. We determined that 120 fishers were necessary to capture 90% of the maximum spatial extent of fishing within our study area from 1990 to 2010, equivalent to 1.1% of male fishers in the region. However, a higher number of elder fishers need to be interviewed to accurately map fishing extent in 1960 to 1980. Participatory maps can provide context for current ecosystem conditions and can support guidelines for management and conservation. Their utility is strengthened by better consideration of the impacts of respondent sample sizes and how this can vary over time for historical assessments.

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Section: Discussionmentioning

confidence: 99%

Section: Study Sitementioning

confidence: 99%

Section: How Much Is Enough?mentioning

confidence: 99%

Section: Essential Role Of Mapsmentioning

confidence: 99%

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How Much is Enough? Improving Participatory Mapping Using Area Rarefaction Curves

Selgrath

Gergel

2019

Land

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“…These changes include more experience in catching Usipa gained over time by fishers, as well as a change in the fishing grounds. In addition, the gear used to target Usipa has greatly been modified as indicated by one of the respondents that the bunt diameter has been increased by 2 fold and others by 3 fold and that the size of the gear has also been increased by simillar margin as the bunt (Sergrath et al, 2018).…”

Section: Fishing Effortmentioning

confidence: 99%

Bioeconomic analysis of Engraulicypris sardella (USIPA) in South east arm of Lake Malawi

Gumulira¹,

Forrester²,

Lazar³

2019

Int. J. Fish. Aquac.

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Usipa Engraulicypris sardella is the most abundant small pelagic species in Lake Malawi. It plays an important part in the lake communities' economy and food security. However, much remains unknown on their stock status and bioeconomic importance. This study is carried out to estimate the maximum economic yield and maximum sustainable yield for Usipa fishery in the Southeast arm of Lake Malawi. Structured quantitative questionnaire was used to collect information from 139 informants on the price of usipa landings and cost of fishing effort. Catch and effort data for Usipa were used in a biomass dynamic model (ASPIC) to estimate key parameters (r, q and k). A bioeconomic model was further developed based on the Gordon-Schaefer model using cost and revenues of the Usipa fisheries to derive the Maximun Sustainable Yield (MSY) and the Maximum Economic Yield (MEY). Model estimates of MSY and MEY were 9,228.8 and 8,227.1 tonnes, respectively. The corresponding fishing effort was estimated to be 40,000 net-hauls and 30,000 net-hauls at MSY and MEY, respectively. Revenues at MSY were estimated at MWK42.280 billion, while at MEY the revenues were MWK39.309 billion. The analysis shows that the current effort of 65,232 net-hauls has a yield of 6,000 tonnes, indicating that the Usipa fishery is currently overexploited over the optimum bio-economic level and even beyond the open access yield. We recommend reducing the fishing effort by 54% to realize the best economic benefits (Production at MEY) and end overfishing to protect the fishery from biological and economic collapses.

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Fishers perceptions of ecosystem service change associated with climate‐disturbed coral reefs

et al. 2021

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Understanding ecosystem service change necessitates an understanding of the social and ecological dimensions of ecosystem services and how they contribute to the well‐being of different people. These empirical research gaps persist across the tropics and in coastal environments, posing a challenge for small island states that depend on ecosystem services associated with near‐shore ecosystems like coral reefs. Perception‐based approaches allow for a rapid appraisal of what constitutes ecosystem service change, providing insights into why these changes matter, and how experiences of change differ between individuals. To capture perceptions of change in four ecosystem services associated with coral reefs (habitat, fishery, coastal protection and recreation services), we conducted 41 semi‐structured interviews with coral reef fishers from Seychelles, where reef ecosystems have been severely impacted by climate disturbance. We gathered quantitative and qualitative data to understand (a) if and what changes in reef‐associated ecosystem services have been perceived; (b) if fishers’ characteristics are associated with differences in perceived changes and (c) which changes matter most in fishers’ lives. Using a three‐dimensional approach to well‐being, we sought to identify whether reasons behind the importance of change connect to fishers’ well‐being. There have been noticeable changes across all four ecosystem services investigated. Changes include social, ecological and behavioural dynamics. Every fisher perceived at least one ecosystem service change but fishers who dive/snorkel or work from larger boats perceived a higher number of ecosystem services to have changed. Education, age and participation in snorkelling/diving were associated with fishers who identified changing habitat services as most important, whereas fishers from families with fewer livelihood alternatives and from smaller islands identified changing fishery services as most important. Different aspects of the subjective, relational and material dimensions of well‐being were implicated in why changing services matter. Despite known ecological shifts in reef condition, this research is one of few studies to empirically show how changes across multiple ecosystem services are being perceived. These perceived changes are complex, engage both the social and ecological dimensions of services, and connect in multiple ways to how fishers feel about their lives, their relationships and material well‐being. A free Plain Language Summary can be found within the Supporting Information of this article.

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Shifting gears: Diversification, intensification, and effort increases in small-scale fisheries (1950-2010)

Cited by 36 publications

References 64 publications

How Much is Enough? Improving Participatory Mapping Using Area Rarefaction Curves

How Much is Enough? Improving Participatory Mapping Using Area Rarefaction Curves

Bioeconomic analysis of Engraulicypris sardella (USIPA) in South east arm of Lake Malawi

Fishers perceptions of ecosystem service change associated with climate‐disturbed coral reefs

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