Trends in Ecology & Evolution
Anecdotes and the shifting baseline syndrome of fisheries
References (4)
- T.D. Smith
Scaling Fisheries
(1994) - M.D. Chapman
Hum. Ecol.
(1987)
Cited by (1795)
Four decades of region- and species-specific trends in lowland stream Ephemeroptera abundance
2024, Science of the Total EnvironmentLowland stream ecosystems are under threat from climate change, industrialization, urbanization, and intensive agriculture. Since the 1980s, improvements in water quality have led to an increase in lowland stream biodiversity. Despite restoration efforts, however, further recovery is often hampered by the presence of region-specific (combinations of) stressors, and species-specific stressor responses. Identification of these stressors may not be achieved by the analysis of abundance data over large areas for entire communities or species assemblages. Therefore, our study introduces an alternative in-depth approach, selecting Ephemeroptera as a model organism group and analyzing 41 years of species abundance data across distinct geographical regions. Our findings revealed that 15 Ephemeroptera species had already disappeared before 1985, emphasizing the importance of evaluating an extended historical period when analyzing biodiversity trends. While biodiversity was generally characterized by an initial recovery that stagnated over time, the analysis of the past 41 years of Ephemeroptera abundance data revealed strong differences in species' abundance trends between periods, regions, and species. Certain species were likely to have benefitted from local restoration measures in specific geographical regions, while others may have declined due to the presence of region-specific stressors. Our approach underscores the importance of studying the development of region- and species-specific stream biodiversity trends over time to aid the selection of the appropriate restoration measures to recover lowland stream biodiversity.
How is mangrove ecosystem health defined? A local community perspective from coastal Thailand
2024, Ocean and Coastal ManagementMangroves, intertidal forests, are increasingly considered a high-priority ecosystem for international conservation efforts. Setting targets for future mangrove conservation and restoration requires understanding of the health of the ecosystem. However, the way ‘ecosystem health’ is defined varies across locations, users, and indices due to differences in knowledge of the ecosystem, scales of the ecosystem being assessed, perceptions of what is ‘healthy’, or because of differences in the way people use or benefit from ecosystems. This can result in misunderstandings which can undermine effective actions to protect and restore functioning ecosystems. Here, we use a case study of a mangrove fishing community in coastal Thailand to examine how local people assess and define mangrove ecosystem health. Through participatory workshops, we show that local people use at least 27 indicators to define mangrove ecosystem health, including biological, physical, and human indices. Mangrove ecosystem health is defined by both direct material benefits derived from the ecosystem, non-material aspects, and the relational value experienced through ‘bundles’ of benefits linked to people's livelihood activities. Our findings suggest that ecosystem health frameworks would be more useful if they incorporated social components and metrics, recognising both the interdependencies between ecosystems and human societies, and that ecosystems possess intrinsic value. Local communities that interact most closely with ecosystems can contribute to improving and operationalising frameworks for ecosystem health.
Diet responses of two apex carnivores (lions and leopards) to wild prey depletion and livestock availability
2024, Biological ConservationPrey-depletion is a significant threat facing carnivores globally, resulting in reduced population numbers, diet alterations, and increased livestock consumption, which increases human-carnivore conflict. We compared the diets of lions (Panthera leo) and leopards (P. pardus) in the prey-abundant Kruger National Park (KNP, South Africa), with that in the prey-depleted/livestock-abundant Limpopo National Park (LNP, Mozambique), using scat analyses. Lions and leopards had broader dietary niche breadths and consumed a greater proportion of smaller (previously suboptimal) prey in LNP relative to KNP. Downshifting in lion and leopard prey size consumption and the continued reliance on previously suboptimal prey may adversely affect carnivore fitness. Diet overlap between lions and leopards was low in both KNP and LNP, suggesting that even when prey is depleted, lions and leopards can partition food resources. Whilst consuming livestock in LNP, lions and leopards strongly avoided cattle (Bos taurus), even though they are the most abundant ungulate in LNP. This suggests that lions and leopards modulate their foraging behavior, so reducing human-carnivore conflict. Efforts to promote carnivore recovery and reduce human-carnivore conflict should focus on prey population restoration, particularly large prey.
Re-grounding cumulative effects assessments in ecological resilience
2024, Environmental Impact Assessment ReviewCumulative effects assessments (CEA) evolved to holistically understand and account for the impact of a spectrum of human and natural disturbances on ecosystems. Yet, the practice of CEA has struggled to overcome siloed and reductionist underpinnings common in the impact assessment arena. One way to move CEA towards more integrated approaches is by drawing on the concept of ecological resilience. Despite gaining considerable attention in other academic spheres, however, ecological resilience remains largely unexplored in CEAs. Motivated by this gap, the objective of this article is to explore how CEAs can be reimagined through an ecological resilience lens to cultivate more integrated and holistic CEA practices. We provide a brief synthesis of CEA theory and practice, highlighting where reductionist, disciplinary, and siloed approaches prevail. Then, we explore three shifts that could recast CEA through the concept of ecological resilience: (1) a shift from valued ecological components to values/identity (resilience pivots), (2) a shift from baseline assessments to ecological trajectories, and (3) a shift from management thresholds to safe operating spaces. We argue that intersecting the practice of CEA with the concept of ecological resilience offers a real opportunity to extend beyond simply being passive respondents to an incremental “death by 1000 cuts” to cultivating the conditions needed for ecological adaption and transformation along desirable pathways.
The good practices of practicable alchemy in the stock assessment continuum: Fundamentals and principles of analytical methods to support science-based fisheries management under data and resource limitations
2024, Fisheries ResearchIt is the exceptionally rare case one can directly and with little uncertainty measure fish absolute abundance through many stock generations in all areas of a stock’s range. Instead, we often seek “gold standard” stock assessments—models that use catch, abundance indices and biological compositions to produce precise and unbiased indicators of stock status for management use. Unfortunately, data and resource limitations affect our ability to collect all the desired information and apply methods with low uncertainty in the results. To confront this challenge of poorly informative data and low resource situations, a host of analytical approaches have been developed to engage the power of fisheries science to inform management decisions despite limitations. These methods are numerous and often challenging to understand and navigate, despite being simplified (though not simple) approaches. It is important to understand where these methods come from, how they can be used, and how to evaluate them. Often they are presented as alchemically providing golden outputs despite heavy assumptions and impure inputs. Here I aim to provide both scientific context of and guidance in organizing and applying so-called data and resource limited stock assessments. I offer a list of best practices by presenting fundamental principles of modelling and highlighting leading edge tools for organizing and conducting analyses under a variety of constraining conditions, offering a conceptualization of stock assessment expressing the interconnectedness of each method and how those can be largely unified under a common modeling framework. The concept of a stock assessment continuum is described, along with discrete examples in the form of a decision tree outlining the major modelling groups for a large variety of data availability scenarios. The basic approach to applied fisheries science and management is presented as interpreting uncertain model outputs (i.e, indicators) using reference points that can then be linked to management decisions via control rules that should express risk tolerance to meeting management objectives in light of uncertain outcomes. The role of simulation testing of management procedures is highlighted in order to evaluate robustness to uncertainty. While more and better data should be a focus of any management system, there is no excuse to wait for golden outputs. We have the tools and theory ready to help direct management of data and resource limited stocks now.
Nearshore fish diversity changes with sampling method and human disturbance: Comparing eDNA metabarcoding and seine netting along the Upper St. Lawrence River
2024, Journal of Great Lakes ResearchAquatic ecosystems are deteriorating, with the most impacted species and populations having insufficient data to inform conservation and management. Monitoring aquatic biodiversity and evaluating anthropogenic impacts typically rely on time-consuming, logistically challenging, and invasive methods (e.g., seining, trawling or electrofishing). Environmental DNA (eDNA) methods have been touted as an important advancement, especially in fish biodiversity assessment. We compare eDNA metabarcoding and seining methods along a 350 km section of the Upper St. Lawrence River (Canada) for: i) mapping the distribution of invasive and threatened fish species, ii) describing species richness and fish community structure, and iii) assessing the effect of habitat type and anthropogenic degradation of riparian zones on fish community composition and richness. eDNA detected more fish species (n = 67) than seining (n = 38) and revealed higher fish diversity in samples adjacent to intact, natural riparian zones. Fish assemblages were influenced by habitat type according to analyses using eDNA, while no effect of any environmental predictor on fish community composition was found using seining. Altogether, our results support eDNA metabarcoding as a powerful, complementary tool in fish monitoring and testing for the impacts of anthropogenic disturbances.