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Kings of their own ocean : tuna, obsession, and the future of our seas
\"In 2004, an enigmatic charter captain named Al Anderson caught and tagged one Atlantic bluefin tuna off New England's coast. Fourteen years later that same fish -- dubbed Amelia for her ocean-spanning journeys -- was caught again, this time in a Mediterranean fish trap. Over his fishing career, Al marked more than sixty thousand fish with plastic tags, an obsession that made him nearly as many enemies as it did friends. His quest landed him in the crossfire of an ongoing fight between a booming bluefin tuna industry and desperate conservation efforts, a conflict that is once again heating up as overfishing and climate change threaten the fish's fate. Kings of Their Own Ocean is an urgent investigation that combines science, business, crime, and environmental justice. Through Karen Pinchin's exclusive interviews and access, interdisciplinary approach, and mesmerizing storytelling, readers join her on boats and docks as she visits tuna hot spots and scientists from Portugal to Japan, New Jersey to Nova Scotia, and glimpse, as Pinchin does, rays of dazzling hope for the future of our oceans.\" -- Page 2 of cover.
Book
albatross and the fish
Breeding on remote ocean islands and spending much of its life foraging for food across vast stretches of seemingly empty seas, the albatross remains a legend for most people. And yet, humans are threatening the albatross family to such an extent that it is currently the most threatened bird group in the world. In this extensively researched, highly readable book, Robin W. Doughty and Virginia Carmichael tell the story of a potentially catastrophic extinction that has been interrupted by an unlikely alliance of governments, conservation groups, and fishermen. Doughty and Carmichael authoritatively establish that the albatross's fate is linked to the fate of two of the highest-value table fish, Bluefin Tuna and Patagonian Toothfish, which are threatened by unregulated commercial harvesting. The authors tell us that commercial fishing techniques are annually killing tens of thousands of albatrosses. And the authors explain how the breeding biology of albatrosses makes them unable to replenish their numbers at the rate they are being depleted. Doughty and Carmichael set the albatross's fate in the larger context of threats facing the ocean commons, ranging from industrial overfishing to our habit of dumping chemicals, solid waste, and plastic trash into the open seas. They also highlight the efforts of dedicated individuals, environmental groups, fishery management bodies, and governments who are working for seabird and fish conservation and demonstrate that these efforts can lead to sustainable solutions for the iconic seabirds and the entire ocean ecosystem.
eBook
Amphibious soul : finding the wild in a tame world
\"In this thrilling memoir of a life spent exploring the most incredible places on Earth--from the Great African Seaforest to the crocodile lairs of the Okavango Delta--Craig Foster reveals how we can attend to the earthly beauty around us and deepen our love for all living things, whether we make our homes in the country, the city, or anywhere in between. Foster explores his struggles to remain present to life when a disconnection from nature and the demands of his professional life begin to deaden his senses. And his own reliance on nature's rejuvenating spiritual power is put to the test when catastrophe strikes close to home. Foster's lyrical, riveting Amphibious Soul draws on his decades of daily ocean dives, wisdom from Indigenous teachers, and leading-edge science\"-- Provided by publisher.
Book
Community-based fish sanctuaries: untapped potential for freshwater fish conservation
Riverine systems and associated fish populations worldwide are threatened by human impacts, especially in tropical countries with emerging economies. In India, community-based fish sanctuaries are a key mechanism for the conservation of freshwater fish populations, but there are few peer-reviewed studies on this subject. Here we integrate over 35 combined years of field experience with a literature synthesis to define and classify community-based fish sanctuaries. We present a novel, critical analysis of fish sanctuaries as social–ecological systems with a functional characterization based on natural capital, ecosystem services, human well-being, and policy and governance. We find that such sanctuaries are shaped by complex social–ecological processes, including coevolution of religious practices and ecological change, feedback processes created by retaliatory conflicts between river users, and diverse and dynamic governance strategies. These sanctuaries hold great potential for the conservation of rare fish species in India, but are subject to myriad threats at local, regional and global scales. Given the complexity of these social–ecological systems, we outline their conservation potential and highlight directions for future research.
Journal Article
Research Progress of the Gut Microbiome in Hybrid Fish
Fish, including hybrid species, are essential components of aquaculture, and the gut microbiome plays a vital role in fish growth, behavior, digestion, and immune health. The gut microbiome can be affected by various internal and/or external factors, such as host development, diet, and environment. We reviewed the effects of diet and dietary supplements on intestinal microorganisms in hybrid fish and the difference in the gut microbiome between the hybrid and their hybrids that originate. Then, we summarized the role of the gut microbiome in the speciation and ecological invasion of hybrid fish. Finally, we discussed possible future studies on the gut microbiome in hybrid fish, including the potential interaction with environmental microbiomes, the effects of the gut microbiome on population expansion, and fish conservation and management.
Journal Article
A new composite abundance metric detects stream fish declines and community homogenization during six decades of invasions
Aim We developed a new technique, utilizing species‐specific counts of individuals from historical fish community samples, to examine landscape‐level, spatio‐temporal trends in relative abundance distributions. Abundance‐based historical distribution analyses are often plagued by data comparability issues, but provide critical information about community composition trends inaccessible to those using analyses based only on species presence–absence. We established trends in native and non‐native fish abundance and community homogenization, uniqueness and diversity to help local conservation managers prioritize targets and motivate similar studies globally to support fish conservation. Location Upper and middle New River (UMNR) basin, Appalachian Mountains, USA. Methods We compiled catch data from 61 years of fish community surveys (1958–2019) and tested for community homogenization by comparing data from repeatedly sampled sites (1900s versus 2000s samples) using dispersion analyses. We measured community uniqueness (site contributions to beta diversity) and species diversity (Shannon index) at sampled streams to identify potential conservation hotspots. We then used regression analyses and Wilcoxon signed‐rank tests to examine species‐specific basin‐wide and local abundance trends and identify species of potential conservation concern. Results Dispersion of sites in species abundance space was significantly greater in the 1900s compared with the 2000s, indicating homogenization had occurred. Of 36 native species analysed, 44.4% (16) showed basin‐wide declines. Non‐native species exhibited mixed patterns; site‐level abundance increased in 2 of 15 species analysed (13%). Main conclusions Our results indicate basin‐wide community homogenization has occurred within the UMNR, but many unique and diverse communities persist. If conserved, these could help maintain regional fish diversity. We found basin‐wide declines in four endemic species, as well as spread patterns of non‐native and native species that were not detected by a presence–absence analysis applied within the same study area. This finding illustrates the importance of considering both species’ abundance and occurrence patterns as separate dimensions of biodiversity to inform conservation planning.
Journal Article
Dispersal and Survival of Captive-Reared Threatened Fishes in a Tonle Sap Lake Reserve
The Tonle Sap Lake in Cambodia supports several species of threatened megafish and contains one of the largest networks of freshwater fish reserves in the world. Despite these traits, this system remains understudied in terms of its utility for endangered fish conservation and restoration. This study was the first of a series of planned fish releases designed to test the effectiveness of conservation supplementation programs in the Tonle Sap Lake. In March 2022 (during the dry season), 1582 captive-reared fishes, including 1538 striped catfish Pangasianodon hypopthalmus, 42 giant barb Catlocarpio siamensis, and two Mekong giant catfish Pangasianodon gigas, were tagged and released into a 986-hectare fish reserve to assess post-release dispersal and survival. Brightly colored external tags with unique identification numbers were used to facilitate tag returns. A high-profile release event was held to raise awareness about the activity, bringing attention to the importance of fish reserves and endangered species conservation, and disseminating information about the research and tag return and reward program. This, in concert with other efforts, served to be an important education and outreach tool and increased tag return rates. We found that mortality from fishing was rapid and very high. Nineteen percent of released fishes were recaptured in the first 2 days after the fish release, and 46% were recaptured by day 83 after the release, indicating intense fishing pressure on the Tonle Sap Lake fisheries. Eighty percent of recaptured fishes were caught in stationary gill nets, most within 10 km of the release site. Fishing mortality rates were independent of fish size or source (pond-reared or cage-reared). Environmental DNA (eDNA) was found to be capable of detecting each of these species’ presence in the water at the release site and could prove to be a useful tool for endangered species monitoring and restoration. Future research should explore alternative release timing, release location, and other methods of increasing post-release survival. Ultimately, underlying sources of mortality, especially fishing, will need to be addressed for conservation supplementation programs to succeed in the Tonle Sap Lake. Conservation supplementation should not be viewed as a substitute for more fundamental conservation measures, such as maintenance of environmental flows, preservation of ecological connectivity, and science-based fisheries management.
Journal Article
Fish conservation in the land of steppe and sky: Evolutionarily significant units of threatened salmonid species in Mongolia mirror major river basins
Mongolia's salmonids are suffering extensive population declines; thus, more comprehensive fisheries management and conservation strategies are required. To assist with their development, a better understanding of the genetic structure and diversity of these threatened species would allow a more targeted approach for preserving genetic variation and ultimately improve long‐term species recoveries. It is hypothesized that the unfragmented river basins that have persisted across Mongolia provide unobstructed connectivity for resident salmonid species. Thus, genetic structure is expected to be primarily segregated between major river basins. We tested this hypothesis by investigating the population structure for three salmonid genera (Hucho, Brachymystax and Thymallus) using different genetic markers to identify evolutionarily significant units (ESUs) and priority rivers to focus conservation efforts. Fish were assigned to separate ESUs when the combined evidence of mitochondrial and nuclear data indicated genetic isolation. Hucho taimen exhibited a dichotomous population structure forming two ESUs, with five priority rivers. Within the Brachymystax genus, there were three B. lenokESUs and one B. tumensisESU, along with six priority rivers. While B. tumensiswas confirmed to display divergent mtDNA haplotypes, haplotype sharing between these two congeneric species was also identified. For T. baicalensis,only a single ESU was assigned, with five priority rivers identified plus Lake Hovsgol. Additionally, we confirmed that T. nigrescens from Lake Hovsgol is a synonym of T. baicalensis. Across all species, the most prominent pattern was strong differentiation among major river basins with low differentiation and weak patterns of isolation by distance within river basins, which corroborated our hypothesis of high within‐basin connectivity across Mongolia. This new genetic information provides authorities the opportunity to distribute resources for management between ESUs while assigning additional protection for the more genetically valuable salmonid rivers so that the greatest adaptive potential within each species can be preserved. Mongolia's salmonids are in decline; therefore, genetically valuable populations must be identified so management resources can be prioritized. Across all species, the most prominent pattern was strong differentiation among major basins with low differentiation and weak patterns of isolation by distance within basins corroborating the hypothesis of high within‐basin connectivity. Conservation priority should focus on priority populations within each ESU, where an ecosystem‐based management approach via the establishment of freshwater protected areas should be implemented.
Journal Article
Capacity shortfalls hinder the performance of marine protected areas globally
Marine protected areas (MPAs) are increasingly being used globally to conserve marine resources. However, whether many MPAs are being effectively and equitably managed, and how MPA management influences substantive outcomes remain unknown. We developed a global database of management and fish population data (433 and 218 MPAs, respectively) to assess: MPA management processes; the effects of MPAs on fish populations; and relationships between management processes and ecological effects. Here we report that many MPAs failed to meet thresholds for effective and equitable management processes, with widespread shortfalls in staff and financial resources. Although 71% of MPAs positively influenced fish populations, these conservation impacts were highly variable. Staff and budget capacity were the strongest predictors of conservation impact: MPAs with adequate staff capacity had ecological effects 2.9 times greater than MPAs with inadequate capacity. Thus, continued global expansion of MPAs without adequate investment in human and financial capacity is likely to lead to sub-optimal conservation outcomes.
Although 71% of marine protected areas are benefiting fish populations, their effects are highly variable, with staff capacity proving to be the most important explanatory variable.
Staff needed to safeguard seas
Marine protected areas are proliferating quickly in the hope of safeguarding marine resources. Here David Gill and colleagues show that inadequate staffing capacity is compromising the efficacy of marine protected areas globally. They analyse fish biomass and management data for marine protected areas around the world and find that, although 71% of these protected areas are benefiting fish populations, the effects are highly variable. Staff capacity was identified as the most important explanatory variable, accounting for around 19% of the variation in the benefits of marine protection. They suggest that continued expansion of marine protected areas around the globe without adequate investment in human and financial capacity could limit marine conservation outcomes.
Journal Article
A new analysis of hypoxia tolerance in fishes using a database of critical oxygen level (Pcrit)
Data were compiled from the literature on the critical oxygen level (Pcrit), a hypoxia-tolerance trait, comprising 96 studies covering 151 fish species from 58 families. Salinity, temperature, body mass, and routine metabolic rate were highly correlated with Pcrit. The effects of temperature, CO2, acidification, metals and feeding are also assessed.AbstractHypoxia is a common occurrence in aquatic habitats, and it is becoming an increasingly frequent and widespread environmental perturbation, primarily as the result of anthropogenic nutrient enrichment and climate change. An in-depth understanding of the hypoxia tolerance of fishes, and how this varies among individuals and species, is required to make accurate predictions of future ecological impacts and to provide better information for conservation and fisheries management. The critical oxygen level (Pcrit) has been widely used as a quantifiable trait of hypoxia tolerance. It is defined as the oxygen level below which the animal can no longer maintain a stable rate of oxygen uptake (oxyregulate) and uptake becomes dependent on ambient oxygen availability (the animal transitions to oxyconforming). A comprehensive database of Pcrit values, comprising 331 measurements from 96 published studies, covering 151 fish species from 58 families, provides the most extensive and up-to-date analysis of hypoxia tolerance in teleosts. Methodologies for determining Pcrit are critically examined to evaluate its usefulness as an indicator of hypoxia tolerance in fishes. Various abiotic and biotic factors that interact with hypoxia are analysed for their effect on Pcrit, including temperature, CO2, acidification, toxic metals and feeding. Salinity, temperature, body mass and routine metabolic rate were strongly correlated with Pcrit; 20% of variation in the Pcrit data set was explained by these four variables. An important methodological issue not previously considered is the inconsistent increase in partial pressure of CO2 within a closed respirometer during the measurement of Pcrit. Modelling suggests that the final partial pressure of CO2 reached can vary from 650 to 3500 µatm depending on the ambient pH and salinity, with potentially major effects on blood acid–base balance and Pcrit itself. This database will form part of a widely accessible repository of physiological trait data that will serve as a resource to facilitate future studies of fish ecology, conservation and management.
Journal Article