Harvesting Pressure Research Articles

Imagination, Reality, and Reproduction: Comparing Perceptions of Coastal Sea Trout Anglers, Real Catches, and Sea Trout Spawning Activity

ABSTRACTSustainable management of recreational fisheries requires balancing angler attitudes and behaviour with fisheries' biological potential. Herein, we investigated the balance in the sea‐run brown trout (Salmo trutta) fishery around the Swedish island of Gotland using data collected through a creel survey, test fishing, and spawning returns to selected streams. Anglers accurately anticipated catches of large fish but underestimated the role of natural reproduction in supporting the stock. Female sea trout entering spawning streams and post‐spawn sea trout caught on the coast were significantly larger than spawning males and non‐spawned fish, and were particularly important for the fishery. Larger sea trout also faced a higher level of harvest pressure than other sizes. Small changes to angler preferences, harvest rates, or regulations could significantly influence characteristics and sustainability of this fishery. The scale and direction of these changes merit further investigation.

Modeling population dynamics of beluga whales in the Eastern High Arctic – Baffin Bay population

AbstractBeluga whales (Delphinapterus leucas) have a long history of subsistence harvest that has continued into the present and a history of exploitation through commercial harvest. The Eastern High Arctic – Baffin Bay (EHA) population of beluga whales has the northernmost distribution of any beluga whale population in Canada. Beluga whales from the EHA population have a single complete abundance estimate from 1996 and 3 partial abundance estimates in 1981, 2010, and 2012 from aerial surveys; reliable estimates from surveys are lacking in recent years, limiting the ability to determine population dynamics. In 2020 satellite imagery was used to estimate abundance for beluga whales in the EHA population for estuaries in the whales' summering area. We built a stochastic stock production model to estimate population dynamics from the start of reliably compiled harvest history data in 1977 to 2022, using abundance estimates from 1981, 1996, 2010, 2012, and 2020. We also extended the model 10 years into the future under 7 potential annual harvest scenarios (within the range of annual reported harvests) to calculate the probability of decline. We estimated the starting population in 1977 as 29,615 whales (95% CI = 20,765–46,251), and the estimate from 2022 was 16,495 whales (95% CI = 6,731–33,504). Landed catch of 0, 100, 200, 300, 400, 500, and 600 beluga whales annually resulted in <1%, 3%, 23%, 50%, 70%, 83%, and 90% probabilities of decline, respectively. There was a notable decrease in abundance over the time series, likely caused by harvest pressure. Harvest in recent years has ranged from 155–553 catches per year, and our results suggest that 108 landed catches per year equates to a 5% risk of decline, the low risk goal for precautionary fisheries management, which aligns with population conservation goals. Our model is a first step in understanding the EHA beluga whale population dynamics using what data are available and suggests that current harvests in some years may result in a population decline and should be monitored.

The geography of wild American ginseng in North Carolina, USA: a comparative study of four capability analysis methods

Wild American ginseng is the root component of a family of plants called Panax, and it grows mainly in the understory of the eastern deciduous forests in North America. The growing market for wild American ginseng in Asia along with the scarcity of this plant in the wild due to rising illegal harvest have been simultaneously pushing up the price of American ginseng in the market, increasing incentives further for illegal harvest of this soon-to-be-extinct species. This paper studies the geography of wild American ginseng to identify the spatial distribution of the suitable habitat of this plant in the wild and provides advice on what conditions are required and what regions are suitable for cultivating it in farms, introducing an alternative to the wild American ginseng to decrease the harvesting pressure on its wild counterpart. By employing four popular geospatial methods, including the Binary Screening method, the Ordinal Ranking method (both Graduated Screening and Addition-of-Factors methods), and the Weighted Linear Combination method, this paper carries out a capability analysis and mapping for wild American ginseng in North Carolina (NC). After building the models, they are validated by using the data of the known locations of wild American ginseng plants in NC. Developing these models helps in gaining a more comprehensive understanding of where the plant naturally grows and sheds light on how government agencies can more effectively and more efficiently plan for law enforcement activities to better protect this plant from illegal harvest. The general pattern of our results suggests that western NC counties such as Jackson, Haywood, Transylvania, Henderson, Cherokee, and Ash are some of the most suitable geographical areas for wild American ginseng to grow. The results of our model validation analysis, along with the comparison of our models' predictions to the observed occurrences of wild American ginseng in nature, indicate that the Binary Screening method’s predictions align with almost 96% of the reported observations in nature. This suggests that the influential natural factors necessary for wild American ginseng are more of complementary factors to each other than being substitutes, meaning that they all must exist in the environment for it to grow, and it could not be that the lack of one natural factor can be compensated by the abundance of another natural factor.

Geometry-modulated all organic 3D printed smart PLA fibers for flextension amplified giant mechanical energy harvesting and Machine learning assisted pressure mapping

Piezoelectret sensors offer a promising avenue for harvesting abundant mechanical energy in the environment, providing a sustainable power solution for low-powered electronics. However, effectively harnessing large impact mechanical energy remains a challenge. In this study, we introduce a novel 3D cylindrical self-powered piezoelectret sensor capable of converting irregular axial impact forces into uniform radial pressures, enabling efficient large-scale impact mechanical energy harvesting. The cylindrical piezoelectret sensor, operating via a flextensional mechanism, was fabricated using 3D printed poly(lactic acid) (PLA) fibers as the piezoelectret layer and poly(3,4-ethylenedioxythiophene) (PEDOT)-coated PLA as the electrode layer. Our cylindrical sensor demonstrates the output voltage, and current of ∼ 11.4 V and 7.2 μA, representing remarkable improvement of 250 % and 160 % respectively, compared to flat fiber membrane device. Furthermore, we leverage IoT connectivity and machine learning techniques to utilize the fabricated robotic sensor for pressure mapping applications. Through machine learning algorithms, we achieve a remarkable accuracy of 100 % in character identification based on sensor data. This work highlights the potential of organic robotic sensors for efficient energy harvesting and intelligent pressure mapping applications, paving the way for the development of sustainable and adaptive sensor systems for various real-world scenarios.

Development and validation of a novel forensic STR multiplex assay for blue (Anthropoides paradiseus), wattled (Bugeranus carunculatus), and grey-crowned crane (Balearica regulorum)

The blue crane (Anthropoides paradiseus), wattled crane (Bugeranus carunculatus), and grey-crowned crane (Balearica regulorum) are species of concern as their populations are declining and they face several threats including habitat loss, disturbance and illegal trade. In South Africa, these species are bred in captivity for trade purposes which is permitted and regulated globally under the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). Legal sustainable trade through captive breeding of endangered wildlife species such as cranes has been promoted to counteract the illegal trade of individuals from the wild. Captive breeding independent of wild populations may reduce the harvest pressures on wild bird populations which in turn benefit the recovery of exploited species. This approach is considered to be controversial by some individuals. Although captive breeding of endangered species, for both population sustainability and commercial purposes, is promoted to aid in conserving species, concerns have been raised with regards to breeding facilities being used for laundering of animals. To monitor the legal trade of cranes in South Africa a short tandem repeat (STR) assay following recommendations of the International Society for Forensic Genetics (ISFG) was developed and validated. An STR assay comprising of four multiplexes that include 16 STR markers and two gender determination markers was proven to be highly informative with average polymorphic information content (PIC) values of 0.806, 0.646 and 0.725 for A. paradiseus, B. regulorum and B. carunculatus respectively. In addition, the assay showed sufficient discriminatory power for parentage assignment of closely related individuals in all three species (A. paradiseus: PI = 1.7×10−24, PIsibs = 4.7×10−08, and B. carunculatus: PI = 1.4×10−19, PIsibs = 2.9×10−07 and B. regulorum: PI = 1.7×10−12, PIsibs = 5.0×10−05). Analysis of 251 samples suggested that the validated multiplex assay ensures reliability, reproducibility, and repeatability for applications in forensic case work where illegal trade of offspring is suspected through verifying parentage of captive birds in breeding facilities.

Recovery of the Seagrass Zostera noltei and Commercial Bivalve Populations After Shellfish Harvesting

Conservation efforts have raised awareness about the impact of small-scale fisheries on the distribution of seagrass plants. The patterns of recovery of the seagrass Zostera noltei and of the commercial bivalves Cerastoderma edule, Ruditapes decussatus and Ruditapes philippinarum after shellfish harvesting were studied in a field experiment in a shellfish bed in NW Spain. Sample plots were subjected to a single disturbance in two types of shellfish harvesting treatments in three zones characterized by different harvesting frequency and seagrass density. The photosynthetic efficiency (Fv/Fm), shoot density, leaf length and carbohydrate content of Z. noltei were monitored every three months during one year, and the C and N content of leaves and biomass of plants were measured one year after the disturbance. The abundance of adults, juveniles and recruits and the condition index of adult bivalves were quantified after the experimental harvesting. Shoot density and biomass of Z. noltei remained low during the ten months after the disturbance but recovered to control values after one year. Carbohydrate contents of apical rhizomes were lower in disturbed (treated) plots, whereas no effect was observed on Fv/Fm. Denser and more complex seagrass patches recovered faster. The abundance of adult bivalves below commercial size was lower in the disturbed plots, while the abundance of adults of commercial size, juveniles and recruits did not vary, indicating that abundance and condition were not hampered by harvesting pressure. The findings also suggest that Z. noltei meadows can recover within one year of the impact of shellfish harvesting if the harvesting areas are rotated and dense patches are preserved.

Harvest of transboundary grey wolves from Yellowstone National Park is largely additive

Abstract Large carnivores are globally threatened due to habitat fragmentation and loss, prey depletion and human exploitation. Human exploitation includes both legal and illegal hunting and trapping. Protected areas can create refugia from hunting and trapping; however, hunting can still threaten wide‐ranging large carnivores when they leave these areas. Large carnivore reintroductions to protected areas are often motivated to restore ecological processes, including wolf reintroduction to Yellowstone National Park (YNP). Determining if harvest is compensatory or additive is essential for informed conservation strategies, as it influences the overall impact on wolf populations and their ecosystems. If harvest was compensatory, then increasing harvest pressure outside YNP should not decrease overall survival for transboundary wolves. Alternatively, if increasing harvest was additive, then increasing harvest pressure outside YNP should decrease overall survival for transboundary wolves. We tested the effects of variable harvest pressure following delisting on the survival of YNP grey wolves (Canis lupus) from 1995 to 2022. We defined three harvest levels: no harvest, harvest with limited quotas and unlimited harvest. We used Cox‐proportional hazards models and cumulative incidence functions to estimate survival rates, factors affecting survival and cause‐specific mortality between these three harvest periods to test predictions of the additive mortality hypothesis. Most harvested wolves that primarily lived in YNP were killed adjacent to the park border. Cox‐proportional hazards models revealed that mortality was highest during years of unlimited harvest during winter outside YNP. Cause‐specific mortality analyses showed that natural mortality from other wolves and harvest were the two leading causes of death, but that harvest mortality had additive effects on wolf mortality. Wolf survival decreased with increased harvest mortality, while natural mortality remained relatively unchanged. Synthesis and applications. High rates of additive harvest mortality of wolves could negatively impact wolf survival in YNP. Harvest mortality of transboundary wolves is additive possibly due to source‐sink dynamics of uneven spatial susceptibility of wolves to harvest mortality across protected area borders, as well as effects of harvest on complex social dynamics of wolves in YNP. Transboundary management of large carnivores is challenging, yet cooperation between agencies is vital for wolf management in and around YNP. Our results support the use of small quota zones surrounding protected areas, that minimize transboundary mortality impacts on large carnivores living primarily inside protected areas.

The Cactus Hunters: Desire and Extinction in the Illicit Succulent Trade

Plant collectors and enthusiasts are attracted to cacti and succulents in part because of their showy flowers in comparison to body size for many species. For example, the cactus genus Mammillaria, among others, is often found in cactus collections. Nevertheless, this human attraction for the collection and growing of cacti has led to an extensive illegal trade of cacti well documented in this book. Cacti over collecting coupled with the fact that 31%, or about1500 cacti species, are considered threatened, results in harvesting pressure that creates environmental concerns for the preservation of these plants. Margulies’s book raises awareness to the problem of cactus collection, trading, and selling both legally and illegally.

Effects of Human Harvesting, Residences, and Forage Abundance on Deer Spatial Distribution.

It has been known that harvesting by humans strongly influences individual within-home range habitat selection of many deer species; however, little is known about the effect of harvesting on coarse-scale habitat selection (i.e., spatial distribution). We examined the summer spatial distribution of sika deer Cervus nippon in relation to human harvesting and other factors, such as human residences, forage abundance, and cover, using pellet group counts at Mount Fuji, central Japan, in 2018. In the study area, harvesting is conducted at medium elevation areas throughout the year, but not at high or low elevation areas where access is difficult or harvesting is prohibited. Spatial distribution of deer was significantly biased to non-harvesting areas and far from residential areas, suggesting that they avoid riskier spaces by establishing a landscape of fear. High-quality food resources (deciduous broad-leaved trees and forbs) were more abundant in harvesting areas than in non-harvesting areas, suggesting that foraging pressure by deer reduce them. However, there were no differences in abundances of more fibrous dwarf bamboo between harvesting and non-harvesting areas, and spatial distribution of deer was significantly biased to higher dwarf bamboo abundance areas, suggesting that the dwarf bamboo is an alternative food resource in non-harvesting areas where supplies of high-quality food were limited. Our results suggest that human harvesting pressure and residences shifted the spatial distribution of deer from the montane forests to subalpine/alpine zones, which may increase damage to vulnerable ecosystems due to severe foraging pressure.

Spring black bear harvest and predation pressure on moose calves in a multi‐predator system

AbstractThe moose (Alces alces; mooz in Anishinaabemowin, Ojibwe language will follow scientific names) is a vital subsistence food source to Anishinabe people of the midwestern United States and has recently declined in Minnesota, USA, with poor calf survival as a contributing factor. Predation is the primary cause of moose calf mortality and we explored whether calf predation rates could be reduced through management of a single predator in a multi‐predator system. Thus, we examined predation rates and causes of calf mortality before (2013–2015) and during (2016–2018) implementation of a spring black bear (Ursus americanus; makwa) harvest season, using baits to attract black bears, on the Grand Portage Indian Reservation, Minnesota, where black bears and gray wolves (Canis lupus; ma'iinganag) are the primary predators of moose calves. We validated our early study findings for the 5 years following the initial study with intermittent spring bear hunting seasons, from 2019–2023. The spring bear hunt was canceled because of a pandemic lockdown in 2020, resumed 2021, and was closed in 2022 and 2023. Black bear harvest prior to adding a spring bear hunting season was 0.038 bears harvested/km2 from 2012–2015, whereas after initiating a spring hunting season (2016–2018) it was 17% higher at 0.046 bears/km2. We observed significantly lower bear predation (by 68%) in association with spring bear management and no compensatory change in the level of wolf predation. The validation years strengthened our findings that spring bear hunting seasons reduce moose calf predation rates, with an overall 68% lower proportion of bear predation on moose calves in the years when spring bear hunts were held. Mean proportion of calf predation attributed to bears was 4.9 times higher (30% vs. 6%) in the years when a spring bear hunt was not held. Despite an increasing wolf density during the study period, we did not observe a compensatory increase in wolf predation during spring bear hunt years. The results of this work suggest that the addition of a spring bear hunt, during a time when moose calves are most vulnerable to bear predation, has the potential to increase moose calf survival even in the presence of wolves.

Brown seaweeds fishery and copper mining production: Two distant economic industries connected by socioecological impacts in Northern Chile

Northern Chile is the scenario of two main activities from a social and economic point of view the: brown seaweeds fishery and cooper mining industry. Chilean brown seaweeds of economic importance, commonly known as kelps, constitute a multi-specific fishery with a workforce of 15,000 people. Four species of kelps are harvested from natural populations by artisanal fishers and exported to world markets as raw material for alginate extraction. On the other hand, copper mining production, contributes 36 % of GDP and it is the major Chilean export commodity. Due to the non-existence of entry barriers to seaweed extraction, this activity has become the sink for unemployment in northern Chile mainly from mining activity. In this context, our results show that when the price of copper is in a downward cycle, it negatively affects the abundance of brown seaweeds, due to the mobility of the workforce to the coastline, increasing the illegal harvest of these marine resources. In contrast, the upward cycle of copper decreases the harvesting pressure, removing illegal harvesters from the coastline and returning them to a mining industry and its suppliers with better wages. These drivers would generate a temporary window for recovery and restoration of brown algae populations, as well as the numerous ecosystem services provided by these engineering organisms.

Introducing the glycyrrhizic acid and glabridin rich genotypes from the cultivated Iranian licorice (Glycyrrhiza glabra L.) populations to exploit in production systems

Currently, the stable, uniform, and highly efficient production of raw materials for pharmaceutical companies has received special attention. To meet these criteria and reduce harvesting pressure on the natural habitats of licorice (Glycyrrhiza glabra L.), cultivation of this valuable plant is inevitable. In the present study, to introduce the glycyrrhizic acid (GA)- and glabridin-rich genotypes from cultivated Iranian licorice, forty genotypes from eight high-potential wild populations were cultivated and evaluated under the same environmental conditions. The GA content varied from 5.00 ± 0.04 mg/g DW (TF2 genotype) to 23.13 ± 0.02 mg/g DW (I5 genotype). The highest and lowest glabridin content were found in the K2 (0.72 ± 0.021 mg/g DW) and M5 (0.02 ± 0.002 mg/g DW) genotypes, respectively. The rutin content in the leaves of the studied genotypes varied from 1.27 ± 0.02 mg/g DW in E4 to 3.24 ± 0.02 mg/g DW in BO5 genotypes. The genotypes from the Ilam population were characterized by higher vegetative growth and yield traits in the aerial parts and roots. The average root dry yield was 2.44 tons per hectare (t/ha) among the studied genotypes and a genotype from Ilam (I5) yielded the maximum value (3.08 ± 0.034 t/ha). The highest coefficient of variation among the genotypes was observed for leaf width (CV = 34.9%). The GA and glabridin-rich genotypes introduced in this study can be used in the future breeding programs to release new bred licorice cultivars.

On the Dynamics of Mortality and the Ephemeral Nature of Mammalian Megafauna.

AbstractEnergy flow through consumer-resource interactions is largely determined by body size. Allometric relationships govern the dynamics of populations by impacting rates of reproduction as well as alternative sources of mortality, which have differential impacts on smaller to larger organisms. Here we derive and investigate the timescales associated with four alternative sources of mortality for terrestrial mammals: mortality from starvation, mortality associated with aging, mortality from consumption by predators, and mortality introduced by anthropogenic subsidized harvest. The incorporation of these allometric relationships into a minimal consumer-resource model illuminates central constraints that may contribute to the structure of mammalian communities. Our framework reveals that while starvation largely impacts smaller-bodied species, the allometry of senescence is expected to be more difficult to observe. In contrast, external predation and subsidized harvest have greater impacts on the populations of larger-bodied species. Moreover, the inclusion of predation mortality reveals mass thresholds for mammalian herbivores, where dynamic instabilities may limit the feasibility of megafaunal populations. We show how these thresholds vary with alternative predator-prey mass relationships, which are not well understood within terrestrial systems. Finally, we use our framework to predict the harvest pressure required to induce mass-specific extinctions, which closely align with previous estimates of anthropogenic megafaunal exploitation in both paleontological and historical contexts. Together our results underscore the tenuous nature of megafaunal populations and how different sources of mortality may contribute to their ephemeral nature over evolutionary time.

Drivers and spatial patterns of avian defaunation in tropical forests

AbstractAimWildlife overexploitation, either for food consumption or for the pet trade, is one of the main threats to bird species in tropical forests. Yet, the spatial distribution and intensity of harvesting pressure on tropical birds remain challenging to quantify. Here, we identify the drivers of hunting‐induced declines in bird abundance and quantify the magnitude and the spatial extent of avian defaunation at a pantropical scale.LocationPantropical.MethodsWe compiled 2968 abundance estimates in hunted and non‐hunted sites across the tropics spanning 518 bird species. Using a Bayesian modelling framework, we fitted species' abundance response ratios to a set of drivers of hunting pressure and species traits. Subsequently, we applied our model to quantify the spatial patterns of avian defaunation across tropical forests and to assess avian defaunation across biogeographic realms, and for species captured for the pet trade or for food consumption.ResultsBody mass and its interactions with hunter accessibility and proximity to urban markets were the most important drivers of hunting‐induced bird abundance declines. We estimated a mean abundance reduction of 12% across the tropics for all species, and that 43% of the extent of tropical forests harbour defaunated avian communities. Large‐bodied species and the Indomalayan realm displayed the greatest abundance declines. Further, moderate to high levels of defaunation extended over 24% of the pantropical forest area, with distinct spatial patterns for species captured for the pet trade (Brazil, China and Indonesia) and for food consumption (SE Asia and West Africa).Main ConclusionsOur study emphasizes the role of hunter accessibility and the proximity to urban markets as major drivers of bird abundance declines due to hunting and trapping. We further identified hotspots where overexploitation has detrimental effects on tropical birds, encompassing local extinction events, thus underscoring the urgent need for conservation efforts to address unsustainable exploitation for both subsistence and trade.

Understanding the effects of egg loss from fisher handling to improve conservation of a threatened freshwater crayfish (Euastacus armatus)

Context Handling of wild animals can have adverse effects on individuals that scale up to affect populations and ultimately species. Limited mobility and high harvest pressure expose the threatened Australian freshwater crayfish (Euastacus armatus) to multiple handling events by fishers that cause egg loss. Aim Our aim was to assess the effects from harvest pressure on the reproductive output of an E. armatus population. Methods A stochastic model based on empirical data and estimated harvest pressures was used to predict the effect of repetitive handling of individuals on a population of E. armatus subject to harvest and consequent egg loss. Key results Egg loss resulted in substantial predicted population-level declines, most pronounced in populations subject to high and extreme harvest pressures. Conclusions We advocate educating fishers to visually determine the reproductive condition of female crayfish by inspecting gonopore setation, eliminating the need for unfurling the tail. Implications Maximising species reproductive output through limiting handling loss supports the management and conservation of E. armatus populations.

Recovery of fishery-stressed seagrass meadows is driven by improvements in wastewater management

As ecosystem engineers, seagrasses provide major benefits to coastal habitats worldwide. Nonetheless, their dynamics remain poorly understood in local areas. Three seagrass (Zostera noltei) meadows located within shellfish beds in Galicia (NW Spain) were selected to assess the intra and inter-annual changes in the habitats by considering the effects of harvesting, temperature and sewage pollution. Seagrass cover increased between April and October, when the sediment temperature ranged from 15 to 20 °C, while in terms of long-term dynamics there was a mean gain of 3 % year−1 between 2004 and 2023. Shellfishing caused mechanical disturbance within the meadows, but the seasonal changes in cover depended on temperature. However, we pointed out the built of new wastewater treatment plants since 1990 that improved water quality as the main driver of the long-term increase in seagrass cover. Environmental policies that enhance seawater quality and limit harvesting pressure are essential to maintain this positive trend.

Aquaculture of emerging species in North-Eastern Atlantic and Mediterranean Sea: a systematic review on sea cucumber farming and potential development

Sea cucumbers are considered a traditional food delicacy in Asian countries. In last decades high market demand, uncontrolled exploitation and inadequate management have led to stock overexploitation, driving commercial interest in new target species and new areas. In recent years, Mediterranean and North-East Atlantic sea cucumbers have become fishing targets, and, due to overfishing, a significant decline of wild populations have been observed, with detrimental effects on benthic communities and ecosystems. Indeed, in addition to being an important economic resource, sea cucumbers play a key ecological role in benthic dynamics where they are involved as ecosystem engineers in the processing of organic matter in the detrital food web pathway. In this context, aquaculture can play a crucial role in supporting the conservation of natural stocks by reducing harvesting pressure on wild populations and enabling restoration programmes for depleted stocks. Commercial sea cucumber farming is already an established reality in the Indo-Pacific region, where it has become one of the most profitable sectors of aquaculture production. In Europe, on the other hand, sea cucumber aquaculture is still an emerging sector, whose development is hampered by poor and fragmented information on the farming requirements of native species. In this context, this systematic review was carried out with the aim of providing a comprehensive summary of the state of the art of farming practices of the European sea cucumbers considered as a target of commercial fisheries. A total of 34 original articles were included in this review, after title, abstract and full-text screening. The results highlighted a sharp increase in the number of studies over the last six years. Portugal, Turkey and Italy are the countries where most research has been carried out. Among the selected species, Holothuria tubulosa was the most studied, while only one article was found on Parastichopus regalis. The main aims of this review were i) to gather all available literature on the farming practices of North-East Atlantic and Mediterranean sea cucumber species, ii) to outline the most common farming practices, iii) to identify gaps and future directions in this emerging aquaculture sector.

Experimental transplantation of Durvillaea incurvata in southern Chile: implication for its restocking

Durvillaea incurvata is a brown macroalgae of ecological, social, and economic importance subjected to a drastic increase in harvesting pressure over the last decade in Chile. In this study, we performed an experimental transplantation of juveniles of D. incurvata, assessing the potential use as a restocking technique. Different types of restocking devices and attaching substrates were constructed. Differences in the D. incurvata re-attachment probability among the substrates and devices were not observed, and a high percentage of juvenile mortality was observed. However, reattached juveniles increased their length, holdfast diameter, and weight. The experiment revealed that juveniles of D. incurvata have a good capacity for re-attachment and growth on artificial substrates after transplantation. This technique could be used for the species stock enhancement, although further studies are needed to optimize the process and increase the juvenile's re-attachment.

Effects of harvesting and an invasive mussel on intertidal rocky shore communities based on historical and spatial comparisons.

Intertidal rocky shores are the most accessible marine habitats and therefore heavily impacted by harvesting. In recent years, they have also been increasingly invaded by alien species, which compounds the effects of harvesting on rocky shore community composition and functioning. Recent survey data, combined with historical data from 1970, were used to assess temporal changes over the intervening period in rocky shore communities at two sites (Wireless Point and Wireless Island). Three kinds of changes emerged: (1) the appearance of alien species; (2) the effects of increased harvesting pressure; and (3) the direct and indirect effects of these changes on other species. A striking result was transformation of mid-shore zones on exposed shores by the appearance of the invasive Mediterranean mussel Mytilus galloprovincialis, and the indirect effects of this on the demography and vertical zonation patterns of the granular limpet Scutellastra granularis. Adult limpets have become excluded by the mussel, whereas juveniles find a secondary home on the shells of the mussel and their abundance has increased. To further disentangle the effects of harvesting from those of alien invasions, a spatial comparison was made between two currently unharvested no-take sites (Scarborough South and Scarborough North) and two regularly harvested sites (Kommetjie and Wireless Point). Harvesting has substantially depleted the granite limpet Cymbula granatina and Argenville's limpet Scutellastra argenvillei. This has led to the proliferation of opportunistic seaweeds, such as Ulva spp. The dual effects of alien invasive species and over-harvesting have major ecosystem effects but do not necessarily diminish biodiversity because the alternative habitats that have developed provide opportunities for colonisation by additional species.

Rethinking extinction “crises”: The case of Asian songbird trade

Abstract Different stakeholders and actors frequently describe environmental challenges as ‘crises’. These crises are often wicked problems that are difficult to resolve due to the complex and contradictory nature of the evidence and knowledge systems surrounding them. Here, we examine a crisis narrative surrounding the IUCN-declared Asian Songbird Crisis (ASC), with its epicentre in Indonesia, where an extensive birdkeeping culture persists. We investigate how bird extinction is perceived by different actors, particularly conservation law enforcement and practitioners working in this space. We unravel local perspectives on the complex relationship between bird trade and extinction through one-to-one interviews and focus groups. Our examination reveals a diversity of attitudes to the ASC, with many law enforcement actors not recognising the crisis label. Market mechanisms result in complex shifts in harvesting pressure onto one or more closely related similar species. The findings challenge the prevailing notion that species extinction significantly affects wildlife trades, emphasising the plastic nature of trade and the coming and going of species fashions. By revealing the divergent views of actors on extinction and the ASC, we highlight the need for shared language, particularly the implications of the ‘crisis’ label, around species extinction.