Mangroves, fisheries and community livelihoods

Mangroves are thought to provide vital ecosystem services to coastal fishing communities through the enhancement of fisheries production. Ongoing loss of mangrove extent globally is therefore of societal concern given that communities living near mangroves rely on mangrove-fishing for income and subsistence. Whilst research and conservation efforts have successfully advocated mangrove restoration, and promoted the importance of mangroves in climate mitigation and coastal protection, knowledge of how people use mangroves for fishing is less well developed (Chapters 1 and 2). To date, most quantitative estimates of the value of the presence of mangroves to fishing have been limited to single fishing sectors, gear types or species groups and therefore fail to capture the full diversity of fishing practices, and thus the true socio-economic benefits of mangrove-fishing. The thesis first develops a definition of what mangrove-fisheries can encompass. A case study which investigated the fishing activities associated with mangroves through interviews with fishers was conducted in the Perancak Estuary, Bali, Indonesia. A framework based on this case study was developed as a flexible tool for identifying the characteristics of a mangrove-fishery in a local context (Chapter 3). Using this framework, Chapter 4 measured the all-encompassing value of mangrove benefits to fishing in the Peam Krasaop Fishing Community (PKFC), Koh Kong Province, southwest Cambodia. The ecosystem service value of mangroves for fishing to households in the PKFC was arrived at using daily landings volumes and market values provided through interview surveys with fishers. Both chapters highlight the highly diverse nature of mangrove-fisheries. To what extent are the benefits of mangrove purely local phenomena or are these benefits reflected in global catch datasets? Chapter 5 investigates the spatial relationships between mangrove extent and fisheries catches at the global scale. For the period 2000-2012, small-scale (artisanal and subsistence) catch data, from the Sea Around Us fisheries catch database, was matched against high resolution mangrove extent maps from the Global Database of Continuous Mangrove Forest Cover for the 21st Century revealing that contrary to much of the previous literature, variation in mangrove-associated species catches is better explained by proximity to the mangrove than by mangrove area. Finally, Chapter 6 considers how new and emergent technologies, such as real-time vessel tracking, are likely to improve our ability to estimate mangrove-fishery value, assesses the potential of restored mangroves in providing ecosystem services, and reflects on how communities will need to respond to pressures on mangrove-fishery livelihoods from global environmental change.  This PhD was funded by the Nippon Foundation Nereus Program

Defining mangrove-fisheries: A typology from the Perancak Estuary, Bali, Indonesia.

This study develops a definition of what mangrove-fisheries can encompass, incorporating a broad range of their possible characteristics. A detailed case study was conducted to develop a typology of mangrove-fishing in the Perancak Estuary, Bali, Indonesia, using interview surveys to investigate the fishing activities associated with mangroves. This case study demonstrated the complexity that a mangrove-fishery can entail, where fishing is connected to the mangrove forest by fishers of multiple sectors, functions, locations and temporal scales. Through a comparison with other mangrove-fishing communities in Bali, it also highlighted that mangrove-fisheries are variable even when in close proximity. With particular reference to this case study, a framework was developed as a flexible tool for identifying the multiple dimensions of a mangrove-fishery in a local context. Following this framework should encourage researchers and managers to look outside of the groups of fishers traditionally expected to benefit from mangrove fishing. This will enable the development of a broader definition of mangrove-fisheries in a site specific way. Identifying the full scope of fishers that contribute to or benefit from a mangrove-fishery is the first step towards building management measures that reflect the interests of groups of fishers that may otherwise remain under-represented. This is in line with international efforts for sustainability, especially in promoting small-scale fishers' access to sustainable resources under the UN Sustainable Development Goals

Defining mangrove-fisheries: A typology from the Perancak Estuary, Bali, Indonesia.

This study develops a definition of what mangrove-fisheries can encompass, incorporating a broad range of their possible characteristics. A detailed case study was conducted to develop a typology of mangrove-fishing in the Perancak Estuary, Bali, Indonesia, using interview surveys to investigate the fishing activities associated with mangroves. This case study demonstrated the complexity that a mangrove-fishery can entail, where fishing is connected to the mangrove forest by fishers of multiple sectors, functions, locations and temporal scales. Through a comparison with other mangrove-fishing communities in Bali, it also highlighted that mangrove-fisheries are variable even when in close proximity. With particular reference to this case study, a framework was developed as a flexible tool for identifying the multiple dimensions of a mangrove-fishery in a local context. Following this framework should encourage researchers and managers to look outside of the groups of fishers traditionally expected to benefit from mangrove fishing. This will enable the development of a broader definition of mangrove-fisheries in a site specific way. Identifying the full scope of fishers that contribute to or benefit from a mangrove-fishery is the first step towards building management measures that reflect the interests of groups of fishers that may otherwise remain under-represented. This is in line with international efforts for sustainability, especially in promoting small-scale fishers' access to sustainable resources under the UN Sustainable Development Goals

Revenue loss due to whale entanglement mitigation and fishery closures.

Whale entanglements with fishing gear, exacerbated by changing environmental conditions, pose significant risk to whale populations. Management tools used to reduce entanglement risk, for example temporary area restrictions on fishing, can have negative economic consequences for fishing communities. Balancing whale protection with sustaining productive fisheries is therefore a challenge experienced worldwide. In the California Current Ecosystem, ecosystem indicators have been used to understand the environmental dynamics that lead to increased whale entanglement risk in a lucrative crab fishery. However, an assessment of socio-economic risk for this fishery, as in many other regions, is missing. We estimate retrospectively the losses from ex-vessel revenue experienced by commercial Dungeness crab fishers in California during two seasons subject to whale entanglement mitigation measures using a Linear-Cragg hurdle modeling approach which incorporated estimates of pre-season crab abundance. In the 2020 fishing season, our results suggest total revenues would have been $14.4 million higher in the Central Management Area of California in the absence of closures and other disturbances. In the 2019 fishing season, our results suggest ex-vessel revenues would have been$9.4 million higher in the Central Management Area and $0.3 million higher in the Northern Management Area. Our evaluation should motivate the development of strategies which maximize whale protection whilst promoting productive, sustainable and economically-viable fisheries

Ecological forecasts for marine resource management during climate extremes.

Forecasting weather has become commonplace, but as society faces novel and uncertain environmental conditions there is a critical need to forecast ecology. Forewarning of ecosystem conditions during climate extremes can support proactive decision-making, yet applications of ecological forecasts are still limited. We showcase the capacity for existing marine management tools to transition to a forecasting configuration and provide skilful ecological forecasts up to 12 months in advance. The management tools use ocean temperature anomalies to help mitigate whale entanglements and sea turtle bycatch, and we show that forecasts can forewarn of human-wildlife interactions caused by unprecedented climate extremes. We further show that regionally downscaled forecasts are not a necessity for ecological forecasting and can be less skilful than global forecasts if they have fewer ensemble members. Our results highlight capacity for ecological forecasts to be explored for regions without the infrastructure or capacity to regionally downscale, ultimately helping to improve marine resource management and climate adaptation globally

Ecological forecasts for marine resource management during climate extremes

<p><span>Forecasting weather has become commonplace, but as society faces novel and uncertain environmental conditions there is a critical need to forecast ecology. Forewarning of ecosystem conditions during climate extremes can support proactive decision-making, yet applications of ecological forecasts are still limited. We showcase the capacity for existing marine management tools to transition to a forecasting configuration and provide skilful ecological forecasts up to 12 months in advance. The management tools use ocean temperature anomalies to help mitigate whale entanglements and sea turtle bycatch, and we show that forecasts can forewarn of human-wildlife interactions caused by unprecedented climate extremes. <span>We further show that regionally downscaled forecasts are not a necessity for ecological forecasting and can be less skilful than global forecasts if they have fewer ensemble members.</span> Our results highlight capacity for ecological forecasts to be explored for regions without the infrastructure or capacity to regionally downscale, ultimately helping to improve marine resource management and climate adaptation globally.</span></p><p>Details for each dataset are provided in the README file.</p> <p>.rds and raster files can be opened in R statistical software. </p> <p>netcdf files can be opened in multiple softwares. </p> <p class="MsoNormal"><span>Datasets included:</span></p> <p class="MsoNormal"><span>(1) Regionally downscaled Sea Surface Temperature Forecasts</span></p> <ul> <li class="MsoNormal"><span>Files used to calculate the downscaled HCI and TOTAL forecasts </span></li> </ul> <p class="MsoNormal"><span>(2) HCI: Habitat Compression Index</span></p> <ul> <li class="MsoNormal">Files used to calculate the HCI forecast, and the HCI forecasts from1985-2020</li> </ul> <p class="MsoNormal"><span>(3) TOTAL: Temperature Observations to Avoid Loggerheads</span></p> <ul> <li>Files used to calculate the TOTAL forecast, and the TOTAL forecasts from1985-2020</li> </ul> <p class="MsoNormal"><span>(4) Source_data</span></p> <ul> <li class="MsoNormal"><span>Source data for each published figure in the manuscript</span></li> </ul><p>Funding provided by: NOAA Climate Program Office<br>Crossref Funder Registry ID: https://ror.org/00mmmy130<br>Award Number: NA17OAR4310108</p><p>Funding provided by: California Current Integrated Ecosystem Assessment*<br>Crossref Funder Registry ID: <br>Award Number: </p><p>Funding provided by: California Ocean Protection Council<br>Crossref Funder Registry ID: https://ror.org/036cr7267<br>Award Number: 2021-242-UCSC</p><h2><span>Summary</span></h2> <p class="MsoNormal"><span>We configure two existing resource management tools, originally configured to use observed (historical) ocean temperatures, to a forecasting system and conduct a retrospective forecast to test their skill. We first conducted a retrospective forecast using global forecasts (73 ensemble members) across the full historically available period (1981-2020) – termed the 'Global' model. Global forecasts of monthly sea surface temperature were obtained from the North American Multimodel Ensemble (NMME; Table S1; <a href="https://www.cpc.ncep.noaa.gov/products/NMME/)"><span><span>https://www.cpc.ncep.noaa.gov/products/NMME/</span></span>)</a>. </span></p> <p class="MsoNormal"><span>We then compared the performance of three forecast configurations: First, we used global forecasts (73 ensemble members) across a reduced historical period (1981-2010) - termed the 'Global Full Ensemble'. Second, we used forecasts regionally downscaled (3 ensemble members) to the CCE for the same reduced historical period (1981-2010) - termed the 'Downscaled Ensemble'. Third, we used a reduced subset of the global forecasts (3 ensemble members) for the same reduced historical period (1981-2010) - termed the 'Global Reduced Ensemble'.  </span></p> <p class="MsoNormal"><span>All forecasts are compared to SST observations, extracted from a CCE regional reanalysis</span><span>. This reanalysis is based on the Regional Ocean Modeling System (ROMS) and covers the west coast of the U.S. (30-48˚N, 134-115.5˚W) with 0.1 degree (~10 km) horizontal resolution and 42 terrain-following vertical levels</span><span>.</span></p> <h2><span>Case Study 1: Habitat Compression Index </span></h2> <p class="MsoNormal"><span>The Habitat Compression Index (HCI) is a regionally resolved measure of cool thermal habitat along the U.S. West Coast; the index presented here monitors surface water conditions off California (35-40°N). The HCI is used to assess the degree to which upwelling habitat (indicated by cool water) is compressed against the coast, as nutrient-rich upwelled waters attract whales seeking enhanced foraging opportunities. </span><span>The HCI was calculated as the number of grid cells with SST lower than a monthly SST threshold within 150 km of the coastline. The HCI was normalized by the total number of grid cells of the 150 km domain to scale values from 0 to 1.  Monthly SST thresholds are the mean monthly SST from 1981-2010 from the coast to 75 km offshore. Low HCI values represent high compression, or reduction of cool thermal habitat, and are the primary interest to resource managers tasked with mitigating whale entanglement risk. The long-term mean of the HCI is used to identify a high compression event (i.e. values below the mean.</span></p> <h2><span>Case Study 2: TOTAL Tool</span></h2> <p class="MsoNormal"><span>The Temperature Observations to Avoid Loggerheads (TOTAL) tool monitors anomalously high SST in the Southern California Bight (31-34°N, 120-116°W) as an indicator of turtle bycatch risk and to recommend potential implementation of a fishery closure</span><span>. TOTAL was calculated as the six-month rolling mean of SST anomalies in the Southern California Bight domain. The spatial closure is potentially enacted during three months of the year (June, July, August) based on SSTA of the preceding six months. If SSTA exceeds a threshold, calculated as the <span>minimum monthly anomaly value preceding three historical closure periods (Aug 2014, Jun-Aug 2015, & Jun-Aug 2016), </span>a closure is recommended</span><span>. </span></p> <h2><span>Skill assessment</span></h2> <p class="MsoNormal"><span>Forecast skill of each management tool was assessed by comparing observed and forecast values using three metrics: (1) correlation coefficient, which<span> provides a statistical measure of the strength of a linear relationship between observed and forecast values; (2) forecast accuracy, which indicates the fraction of correct forecasts</span>; and (3) the <span>Symmetric Extremal Dependence Index (</span>SEDI) which has several properties that make it well suited to quantifying skill for rare events</span><span>. Details and equations for metrics are described in the manuscript.</span></p&gt

Local ecological knowledge and perception of the causes, impacts and effects of Sargassum massive influxes: a binational approach

ABSTRACTCoastal communities of the Caribbean Sea and Gulf of Mexico have been affected by atypical influxes of pelagic macroalgae (Sargassum genus) since 2011, entailing ecological, economic and social impacts in need of characterization. We compiled and documented local ecological knowledge (LEK) and perceptions across diverse stakeholder groups from coastal communities in Mexico (Quintana Roo) (n=50 participants) and the United States (Florida) (n=36 participants) through on-site and online interviews and workshops undertaken from January to March of 2022, to understand how the knowledge of this phenomenon varies among communities and to characterize ecological and well-being impacts. Participants in Quintana Roo associated these influxes with both global phenomena (e.g., climate change) and local scale processes (e.g., currents/wind patterns) while Florida participants associated these events more with the latter. The communities in both regions perceived that the economy and the environment were the most impacted well-being categories. While influxes effects were mostly negative (80%) according to Quintana Roo participants (e.g., affected fisheries), Florida participants considered many positive effects of Sargassum (40%) on several well-being and ecological components (e.g., nursery habitat for marine species). In general, the perception of Sargassum as a problem was less pronounced in Florida, and these differences in perception are related to the magnitude of these influxes’ effect on the daily life of these communities. Overall, macroalgae management is still mainly focused on beach cleanup. Documenting LEK is important to delineate scientific research priorities and to provide decision makers with resources to develop efficient public policies and coastal management decisions

An anchovy ecosystem indicator of marine predator foraging and reproduction.

Forage fishes are key energy conduits that transfer primary and secondary productivity to higher trophic levels. As novel environmental conditions caused by climate change alter ecosystems and predator-prey dynamics, there is a critical need to understand how forage fish control bottom-up forcing of food web dynamics. In the northeast Pacific, northern anchovy (Engraulis mordax) is an important forage species with high interannual variability in population size that subsequently impacts the foraging and reproductive ecology of marine predators. Anchovy habitat suitability from a species distribution model (SDM) was assessed as an indicator of the diet, distribution and reproduction of four predator species. Across 22 years (1998-2019), this anchovy ecosystem indicator (AEI) was significantly positively correlated with diet composition of all species and the distribution of common murres (Uria aalge), Brandts cormorants (Phalacrocorax penicillatus) and California sea lions (Zalophus californianus), but not rhinoceros auklets (Cerorhinca monocerata). The capacity for the AEI to explain variability in predator reproduction varied by species but was strongest with cormorants and sea lions. The AEI demonstrates the utility of forage SDMs in creating ecosystem indicators to guide ecosystem-based management

Supplementary methods and results for An anchovy ecosystem indicator of marine predator foraging and reproduction

Forage fishes are key energy conduits that transfer primary and secondary productivity to higher trophic levels. As novel environmental conditions caused by climate change alter ecosystems and predator–prey dynamics, there is a critical need to understand how forage fish control bottom-up forcing of food web dynamics. In the northeast Pacific, northern anchovy (Engraulis mordax) is an important forage species with high interannual variability in population size that subsequently impacts the foraging and reproductive ecology of marine predators. Anchovy habitat suitability from a species distribution model (SDM) was assessed as an indicator of the diet, distribution and reproduction of four predator species. Across 22 years (1998–2019), this anchovy ecosystem indicator (AEI) was significantly positively correlated with diet composition of all species and the distribution of common murres (Uria aalge), Brandt's cormorants (Phalacrocorax penicillatus) and California sea lions (Zalophus californianus), but not rhinoceros auklets (Cerorhinca monocerata). The capacity for the AEI to explain variability in predator reproduction varied by species but was strongest with cormorants and sea lions. The AEI demonstrates the utility of forage SDMs in creating ecosystem indicators to guide ecosystem-based management