Abundance Of Target Species Research Articles

Transfer seeds, hay, or soil blocks? The importance of the completeness of biological inputs to address dispersal and establishment limitations during the restoration of plant assemblages in floodplain grasslands

This study investigated different techniques of grassland restoration to overcome dispersal or establishment limitation, which are key processes influencing early‐successional plant community assembly. A fully randomized in situ experiment was set up in a former arable land in a floodplain along the Garonne river (south‐western France) to test for the effect of (1) the type and completeness of the biological input (any biological material—seed, hay, and soil—transferred to the site under restoration), (2) soil disturbance by deep tillage, and (3) their interaction on plant community dynamics for 5 years. All inputs influenced the plant community structure and composition. The effects depended on the type of the input but not necessarily in link with its completeness. High density and diversity seed mixture led to high levels of richness and relative abundance of target species like soil blocks, the input considered as the most complete. During the first year, hay transfer mostly influenced community assembly through negative litter effects. Delayed germination of several species contributed to buffer these early effects. This study supports the importance of dispersal limitation during early succession in degraded grassland ecosystems whereas soil disturbance had only subtle effects on the seed bank and standing plant community, indicating that competition and establishment limitation were of secondary importance in our study system. Our results suggest that even low‐frequency immigration events (e.g. when a few seeds are transferred within hay) can be of great importance providing that a sufficiently long time period is considered for grassland restoration.

Suspended Materials Affect Particle Size Distribution and Removal of Environmental DNA in Flowing Waters.

Environmental DNA (eDNA) in aquatic systems is a complex mixture that includes dissolved DNA, intracellular DNA, and particle-adsorbed DNA. Information about the various components of eDNA and their relative proportions could be used to discern target organism abundance and location. However, a limited knowledge of eDNA adsorption dynamics and interactions with other materials hinders these applications. To address this gap, we used recirculating stream mesocosms to investigate the impact of suspended materials (fine particulate organic matter, plankton, clay, and titanium dioxide) on the eDNA concentration and particle size distribution (PSD) from two fish species in flowing water. Our findings revealed that eDNA rapidly adsorbs to other materials in the water column, affecting its concentration and PSD. Nonetheless, only particulate organic matter affected eDNA removal rate after 30 h. Moreover, we observed that the removal of larger eDNA components (≥10 μm) was more strongly influenced by physical processes, whereas the removal of smaller eDNA components was driven by biological degradation. This disparity in removal mechanisms between larger and smaller eDNA components could explain changes in eDNA composition over time and space, which have implications for modeling the spatial distribution and abundance of target species and optimizing eDNA detection in high turbidity systems.

Multiple stressors prevent gains in native plant diversity following invasive species removal

AbstractLand managers spend substantial resources managing invasive species to mitigate their negative ecological and economic impacts. However, invasive species management is seldom coupled with empirical assessments of management outcomes or the ecological impacts of the target species. Additionally, the study of invasive species has, until recently, neglected to acknowledge co‐stressors on native communities, which often are the drivers of ecological degradation. We assessed the effects of the invasive plant Vincetoxicum rossicum and its removal on understory plant communities, as well as whether these effects were mediated by deer and invasive earthworms. We used paired fenced and open plots with V. rossicum and an open plot without V. rossicum at each of the three forested sites in New York State Parks from 2017 to 2020. Following a nested design, we located paired sets of open and fenced plots in areas where V. rossicum was experimentally removed and in areas where it was unmanaged. After three years of V. rossicum removal, V. rossicum significantly declined. However, the ultimate goal of management was native plant recovery. Contrary to this aim, native plant diversity and cover increased if V. rossicum was left unmanaged but did not change with V. rossicum removal. Thus, we provide strong evidence that reducing target species abundance does not always translate into native plant recovery. This disparity may be because deer and invasive earthworms are stronger drivers of understory plant communities than V. rossicum, as native plant cover and diversity were lower the more earthworms were in a plot and invasive plant species declined after fencing to exclude deer. Management that prioritizes reducing deer and earthworm impacts over invasive plant removal is therefore worth exploring, especially when coupled with continued monitoring to assess if these actions result in the desired management outcomes. Overall, our findings underscore the need to collect data to test management assumptions: reducing the abundance of an invader may not always result in native plant recovery, especially if other stressors are the ultimate drivers of change in invaded communities.

Reversing declines in farmland birds: How much agri‐environment provision is needed at farm and landscape scales?

Abstract Agri‐environment schemes (AES) are the primary policy mechanism for addressing farmland biodiversity declines across Europe. Despite previous studies on the impacts of AES on biodiversity, there is little empirical evidence on the scale of provision required to reverse declines. Across three regions of lowland England with contrasting farm systems (arable, pastoral, mixed), we estimated avian population growth rates (PGRs) on farmland with high AES provision (‘higher‐tier’: average bird‐friendly option cover = 7.4%), low AES provision (‘lower‐tier’: 2.3%) and no bird‐friendly AES (‘no AES’). Ten‐year PGRs were derived for 24 species and three multi‐species groups comprising farmland‐associated species (‘farmland birds’), species of conservation concern (‘priority birds’) and species restricted to farmland (‘specialist birds’). We used PGRs to simulate the proportion of the regional farmland landscape that would have to be assigned to higher‐ and lower‐tier agreements to stabilise or increase populations. In the arable and pastoral regions, 13/23 and 13/22 species, respectively, had more positive PGRs under higher‐tier AES than on no AES farmland (none had more negative PGRs), compared to 4/22 (positive) and 1/22 (negative) in the mixed region. Only two to four species per region exhibited more positive PGRs under lower‐tier AES compared to no AES farmland. Multi‐species PGRs in the arable and pastoral regions increased from no AES (strong decline), to lower‐tier (decline or stability) to higher‐tier (moderate or strong increase). There was no overall AES effect in the mixed region. To increase regional farmland bird populations by 10% over 10 years, 47% and 26% of the farmed landscape would need to be devoted to higher‐tier agreements in arable and pastoral landscapes respectively. This falls to 34% and 17% when higher‐tier is targeted at localities supporting higher abundances of target species, and to 29% and 10% when 30% of the farmed landscape is also devoted to lower‐tier. Priority and specialist birds require higher provision levels. Policy implications. Where farmland bird recovery is an AES objective, farms should prioritise higher‐tier agreement delivery over lower‐tier. Farmland bird responses to AES provision are likely to vary regionally, but careful targeting will reduce the amount needed in the landscape.

On the occasion of the 30th anniversary of Fisheries Oceanography

I would like to express my sincere congratulations on the 30th anniversary of the founding of Fisheries Oceanography. At that time, Professor T. R. Parsons of the University of British Columbia, Canada, and Professor Takashige Sugimoto of the Ocean Research Institute of the University of Tokyo led the preparations for the establishment of an international academic journal “Fisheries Oceanography (FOG)” with the aim of deepening the discipline of fisheries oceanography on a global scale. The Japanese Society of Fisheries Oceanography (JSFO) defines the main research areas of fisheries oceanography as (1) oceanographic conditions that define the distribution of fishery-useful species, (2) oceanographic tools for estimating the abundance of target species and the productivity of fishing grounds, (3) oceanographic conditions for predicting changes in distribution and abundance, and (4) oceanographic contributions to the enhancement and development of fishery productivity. There were growing expectations for the establishment of an international academic journal that would meet these requirements. Prior to the journal establishment, JSFO held the 30th Anniversary Symposium “Promising Fisheries Oceanography in Japan” in Japan in 1991, and in 1986, the 25th Anniversary Symposium “Fisheries and Fisheries Oceanography in the Coming Century” was held in Tokyo, inviting Dr. D. H. Cushing (UK) and Dr. R. Lasker (USA) as keynote speakers. These symposia gave the momentum to publish the journal with an association in Japan. In the end, FOG was first published by Blackwell Scientific Publications (UK) in 1992 with JSFO as the sponsoring association. Now published by John Wiley & Sons, FOG has been the international journal of the JSFO since 2001. At that time, I had just started my research career and I remember that I had been supporting Professor Sugimoto in his efforts to encourage more important and cutting-edge papers to be submitted to the journal and to develop it into a high-level international academic journal. On this occasion of the 30th anniversary of FOG, it is with great emotion that I address you as the President of JSFO. Researchers in fisheries oceanography are expected to develop research related to both fisheries and the ocean that is closely linked to the field of fishing, and FOG has the scent of fish and the scent of the ocean. FOG is a unique international academic journal, and it can be said to be an international academic journal that was inspired by Professor Michitaka Uda, the first president of the JSFO. The FOG not only strives for the exploration of fisheries oceanography as a basic science but has also made a great contribution to the development of fisheries oceanography by producing many talented human resources to educational/research institutions, government agencies, and industry. Many Japanese fisheries oceanographers have contributed to FOG, and I am very proud to be one of them. On the other hand, the current situation surrounding the oceans is changing dramatically, as exemplified by the marine litter/plastic problem, the development of marine renewable energy, and global warming. In addition to exploring the universal principles of the natural world, there is an increasing need to develop research that integrates natural science with social science, such as international maritime law and ocean policy, in order to solve the various problems facing human society. Furthermore, in addition to the exclusive economic zone (EEZ), a new marine legal order, such as the marine biological diversity of areas beyond national jurisdiction (BBNJ), is being sought, which will contribute to conservation of biological diversity, but may make free and open research even more difficult because many countries relate to the order and regulate each other too much, even for purely basic scientific inquiry. FOG is expected to continue to make a significant role to the development of fisheries oceanography, but it will also be required to conduct research that directly contributes to measures for the sustainable use of marine living resources. The Japanese Society of Fisheries Oceanography will celebrate its 60th anniversary in 2022. The JSFO is committed to contributing to the further development of Fisheries Oceanography, and we hope that FOG will continue to be a bridge that connects fisheries oceanographers around the world. At the end of this article, I would like to wish FOG continued success.

Estimating ecological carrying capacity for stock enhancement in marine ranching ecosystems of Northern China

Marine ranching has been proposed as a promising solution to manage the depleted coastal fishery ecosystem in recent decades across China. Marine ranching integrates the practices of artificial habitat-based with aquaculture-based enhancement. Assessing the ecological carrying capacity of target species for enhancement is a precondition for determining the optimal numbers for release, particularly for those species whose habitat restrictions have been eliminated through the construction of artificial habitats in the marine ranch. A responsible approach to stock enhancement aims not only to increase total yield and stock abundance but also to consider any potential effects on ecosystem structure and function. A time-dynamic, ecosystem model was constructed using Ecopath with Ecosim for the Laizhou Bay (Bohai Sea) marine ranching ecosystem in the nearshore waters of northern China. Two sedentary target species with potential for stock enhancement, i.e., the carnivorous red snail Rapana venosa and the detritivorous sea cucumber Apostichopus japonicus, were selected to simulate and estimate their ecological carrying capacities and project their overall effects on the ecosystem. Ecological carrying capacity was defined as the maximum standing stocks of the target species that would not cause “unacceptable” impacts on the ecosystem function and resilience, i.e., not cause any other group’s biomass to fall below 10% of its original biomass. The ecological carrying capacities estimated for R. venosa and A. japonicus were 623.46 and 200.57 t·km−2, respectively, corresponding to 7.8 and 5.0 times higher than their current standing stocks. Simulations of R. venosa enhancement showed distinct effects of increased target species abundance on other functional groups and ecosystem properties. An increase in red snail biomass caused negative impacts on the biomass of most other functional groups and ecosystem indicators, such as Finn’s cycling index, transfer efficiency, and Kempton’s Q index. In contrast, the simulated A. japonicus enhancement had relatively few impacts, and the biomasses of most other functional groups and ecosystem indicators did not change or changed very slightly (<5%). The current model framework provides a means of estimating the ecological carrying capacity in commercial-scale stock enhancement practices and avoiding potential ecological risks for marine ranching in northern China.

Impact of woodland agri-environment management on woodland structure and target bird species

Agri-environment incentives form a central mechanism supporting changes to land management to provide public benefits. This study assesses the medium-term effects of woodland management on 13 target, specialist woodland bird species, as well as other woodland birds in a single region of the UK. The abundance of breeding birds (using two methods: point counts and territory mapping) and metrics of woodland structure were recorded on sites with Woodland Improvement Grants (improvement sites) and nearby comparison sites (control sites). Initial measurements were made prior to management and repeated 7–9 years later. A separate comparison of changes in bird abundance was made between the managed woodland sites and woodland from similar landscapes surveyed as part of the national Breeding Bird Survey (BBS). There was an increase in abundance of target species on improvement sites compared to a decrease on both control sites and BBS sites, although this was only evident from point count data. The effects on target species were stronger than for other woodland specialists and there was no apparent effect on woodland generalists, suggesting that the management interventions were appropriate for the target species. Changes in woodland structure were generally consistent with the expected effect of management, with lower tree density and greater Bramble (Rubus sp.) cover. However, contrary to the aim of increasing understorey cover, a reduction was recorded within the 2–10 m height category in improvement sites. This contrast is due to the removal of young trees during thinning affecting this height band and the short time period since management to allow regrowth. Our findings show that bespoke management supported through government agri-environment incentives can have a positive impact on target woodland birds. For managed forests, identifying species requirements and how management can be adapted to improve their habitats can be an effective way of delivering biodiversity gains when financial incentives are provided to achieve policy goals.

Meta‐analyses of environmental DNA downstream transport and deposition in relation to hydrogeography in riverine environments

Abstract Environmental DNA (eDNA) analysis is a promising tool to monitor species distribution and abundance in aquatic ecosystems. These estimates can be biased in lotic environments by the effects of eDNA transport and deposition processes. However, our understanding of eDNA downstream transport dynamics is limited because it can fluctuate greatly depending on target species abundance and eDNA quantity in a source site and the design of aquatic sampling. Furthermore, eDNA deposition into bottom substrates also determines the availability of aqueous eDNA, but knowledge about deposition is much more limited. Consequently, there is little consensus about eDNA downstream transport and deposition, as well as their interactions with hydrogeographic conditions. In this study, we compiled previous papers concerning riverine eDNA transport and synthesised knowledge about eDNA transport and deposition. A few studies have recently applied a hydrodynamic modelling approach and calculated the average length of eDNA downstream transport (Sw) and velocity of eDNA deposition (Vdep). Referring to those studies, we manually calculated, or directly extracted, Sw and Vdep from the nine eDNA papers and conducted meta‐analyses to reveal the association of these estimates with river discharges. Furthermore, we simulated the mean length of eDNA downstream transport in a channel with given hydrogeographic conditions. The estimated Sw and Vdep values ranged from 2.6 to 13,187.4 m and 0.003 to 1.900 mm/s, respectively. When log‐transformed, the median Sw and Vdep values were 102.188 (= 154.1) m and 10–1.387 (= 0.041) mm/s. The calculated maximum eDNA transport distances until 95% and 99% of the target eDNA particles are deposited ranged from 334.0 to 1,272.7 m and 513.5 to 1,956.4 m, respectively. Moreover, we found that river discharges were positively associated with Sw, whereas Vdep was lower for natural environments than mesocosms. This trend could be due to other environmental factors, such as bottom substrates. Our meta‐analysis implied that, under ordinary hydrogeographic conditions, most eDNA particles could travel less than 2 km downstream even when considering the resuspension of eDNA from riverbeds. By contrast, our study did not consider multiple environmental factors that potentially affect eDNA transport and would accordingly introduce a moderate to high degree of heterogeneity across studies. These issues will be addressed in future studies. To our knowledge, this study is the first to quantitatively synthesise the length of eDNA downstream transport in riverine environments and infer general properties of eDNA downstream transport distance and deposition velocity. According to our results, much of the eDNA released from individuals might have little effect on the detection of target eDNA in the sampling sites more than 2 km downstream. Although further accumulation of empirical studies is necessary, our findings propose the groundwork for optimal eDNA sampling designs in riverine ecosystems to reduce the false‐positive inference of species presence and false‐negative eDNA detection.

Unmanned aerial vehicles as a useful tool for investigating animal movements

Abstract Determining animal abundance is crucial for assessing the effectiveness of management measures against pest animals. Meanwhile, investigating animal movements has become important for conducting abundance estimations of unmarked animals since the random encounter model (REM) was published. REM is a camera trapping method that derives animal density by using contact ratio between camera traps and targeted animals that randomly move at a certain speed in a given area. However, it requires an independent value, which is animal speed. For investigating animal speed, camera traps with video recording and GPS tagging are the commonly used tools. Unmanned aerial vehicles (UAVs) are currently used in wildlife monitoring to investigate the abundance of target species. It is evaluated as a tool that is non‐invasive and suitable for surveys in inaccessible landscapes. Considering these characteristics, we regarded a distant survey using this technology as suitable for investigating animal movements. Therefore, we proposed a method for estimating animal movements using UAVs and conducted a case study that aimed to investigate wild boars' movements. We collected 11 video samples that successfully followed the movements of wild boars from 26 UAV flights in total, and the average speed of their movements derived from all the samples was 1.54 km/24 hr. We found that issues can be improved, including species identification, video sample length, and animal behaviours or activity patterns. On the other hand, our method showed potential for applying to species with specific characteristics in their body size, shape or activity patterns. With improvements in the issues mentioned above, UAVs would become an alternative tool for investigating animal movements.

Environmental DNA preserved in marine sediment for detecting jellyfish blooms after a tsunami

Environmental DNA (eDNA) can be a powerful tool for detecting the distribution and abundance of target species. This study aimed to test the longevity of eDNA in marine sediment through a tank experiment and to use this information to reconstruct past faunal occurrence. In the tank experiment, juvenile jack mackerel (Trachurus japonicus) were kept in flow-through tanks with marine sediment for two weeks. Water and sediment samples from the tanks were collected after the removal of fish. In the field trial, sediment cores were collected in Moune Bay, northeast Japan, where unusual blooms of jellyfish (Aurelia sp.) occurred after a tsunami. The samples were analyzed by layers to detect the eDNA of jellyfish. The tank experiment revealed that after fish were removed, eDNA was not present in the water the next day, or subsequently, whereas eDNA was detectable in the sediment for 12 months. In the sediment core samples, jellyfish eDNA was detected at high concentrations above the layer with the highest content of polycyclic aromatic hydrocarbons, reflecting tsunami-induced oil spills. Thus, marine sediment eDNA preserves a record of target species for at least one year and can be used to reconstruct past faunal occurrence.

Biodiversity protection in the 21st century needs intact habitat and protection from overexploitation whether inside or outside parks

Biodiversity protection in the 21st century needs intact habitat and protection from overexploitation whether inside or outside parks

Optimizing speleological monitoring efforts: insights from long-term data for tropical iron caves.

Understanding the factors underpinning species abundance patterns in space and time is essential to implement effective cave conservation actions. Yet, the methods employed to monitor cave biodiversity still lack standardization, and no quantitative assessment has yet tried to optimize the amount and type of information required to efficiently identify disturbances in cave ecosystems. Using a comprehensive monitoring dataset for tropical iron caves, comprising abundance measurements for 33 target taxa surveyed across 95 caves along four years, here we provide the first evidence-based recommendations to optimize monitoring programs seeking to follow target species abundance through time. We found that seasonality did not influence the ability to detect temporal abundance trends. However, in most species, abundance estimates assessed during the dry season resulted in a more accurate detection of temporal abundance trends, and at least three surveys were required to identify global temporal abundance trends. Finally, we identified a subset of species that could potentially serve as short-term disturbance indicators. Results suggest that iron cave monitoring programs implemented in our study region could focus sampling efforts in the dry season, where detectability of target species is higher, while assuring data collection for at least three years. More generally, our study reveals the importance of long-term cave monitoring programs for detecting possible disturbances in subterranean ecosystems, and for using the generated information to optimize future monitoring efforts.

Spatial Heterogeneity of eDNA Transport Improves Stream Assessment of Threatened Salmon Presence, Abundance, and Location

The integration of environmental DNA (eDNA) within management strategies for lotic organisms requires translating eDNA detection and quantification data into inferences of the locations and abundances of target species. Understanding how eDNA is distributed in space and time within the complex environments of rivers and streams is a major factor in achieving this translation. Here we study bidimensional eDNA signals in streams to predict the position and abundance of Atlantic salmon (Salmo salar) juveniles. We use data from sentinel cages with a range of abundances (3–63 juveniles) that were deployed in three coastal streams in New Brunswick, Canada. We evaluate the spatial patterns of eDNA dispersal and determine the effect of discharge on the dilution rate of eDNA. Our results show that eDNA exhibits predictable plume dynamics downstream from sources, with eDNA being initially concentrated and transported in the midstream, but eventually accumulating in stream margins with time and distance. From these findings we developed a fish detection and distribution prediction model based on the eDNA ratio in midstream versus bankside sites for a variety of fish distribution scenarios. Finally, we advise that sampling midstream at every 400 m is sufficient to detect a single fish at low velocity, but sampling efforts need to be increased at higher water velocity (every 100 m in the systems surveyed in this study). Studying salmon eDNA spatio-temporal patterns in lotic environments is essential to developing strong quantitative population assessment models that successfully leverage eDNA as a tool to protect salmon populations.

North Atlantic Oscillation and fisheries management during global climate change

The North Atlantic Oscillation (NAO) is the most important large-scale climatic oscillation affecting the North Atlantic region. The variability introduced by the NAO affects many meteorological parameters, including wind speed and direction, and differences in air temperature and rainfall, particularly during the boreal winter. The NAO is also known to affect the ocean by changing heat content, sea surface temperature, gyre circulation, mixed layer depth, salinity, high-latitude deep water formation, and sea ice cover. Consequently, the NAO has been widely used to analyze the variability of marine ecosystems. Several researchers found that fishery resources were teleconnected with the NAO variability, resulting in a significant relationship between this climatic oscillation and fishery yields. More precisely, the NAO affects the target species abundance, recruitment, catchability, and body condition. These effects can be cumulative over time and act synergistically. In this study, the available information about this topic is reviewed, and the importance of the NAO as a large-scale climatic oscillation in fisheries management is discussed using an ecosystem approach. We also discuss the possible effects of climate change on Atlantic and Mediterranean fisheries if this change were to affect the NAO pattern.

Biogeophysical influence of large-scale bathymetric habitat types on mesophotic and upper bathyal demersal fish assemblages: a Hawaiian case study

Seamounts, pinnacles, and crests are abrupt seafloor features that modify physical processes and ecological patterns. Fishers often target these local bathymetric highs, which can have high catch-per-unit-effort. Increases in the abundance of target species has been qualitatively noted around these features and promontories, however, a quantitative evaluation of local highs as preferred habitat for fishes is still lacking. Here, we used an extensive database of fish abundances (N = 2381) from mesophotic and upper bathyal depths (40-300 m) gathered over 8 yr around the Main Hawaiian Islands to evaluate the effects of macro-scale habitat categorized by combining bathymetric position index (BPI) and slope. A numerical model simulating physical ocean processes was used to test the hypothesis that local highs, herein called crests, are distinct and preferred habitat for many species due to their modified flow conditions. We show that crests host a unique, diverse fish assemblage with double the abundance relative to other habitats. Therefore, fishes are concentrated at crests rather than being uniformly distributed along the island shelf at preferred depths. These habitats are characterized by enhanced current amplitudes and convergence zones. Direct correlations between fish abundance, convergence, and current amplitude strongly suggest that flow-enhanced food availability is likely the driver of habitat-related changes in fish assemblage. These results have important implications for conservation and management. We identify a simple and informative method to classify habitat, quantitatively link bathymetry-induced flow alterations to fish abundances, and provide information for refining definitions of essential fish habitat for species that are important commercial targets worldwide.

Using an integrative approach to evaluate shrimp bycatch from subtropical data-poor fisheries

Tropical and subtropical shrimp fisheries occur mainly nearshore, where numerous non-target species (bycatch) are captured. Bycatch is a serious issue for fishing activity and understanding its impacts through integrative analyses of the bycatch structure is necessary. In Brazil, information on bycatch composition and structure is limited. As such, we conducted a study on the target species and bycatch communities from a fishery area in the southern Brazilian coast, considering a 20-year dataset. The target species abundance was influenced by seasonal conditions, where peaks of abundance occurred from February to May and August to October. The trawl captures comprised 149 species, of which 116 species were discarded and 33 were considered usable by the fishermen. The bycatch composition had few abundant and several rare species, with a high bycatch rate associated with salinity and TSS, mainly in the latter years of study. Bycatch diversity showed association with salinity, and multiyear oscillations, but generally maintained a stable trend over years. Our analysis revealed bycatch patterns and the influence of environmental variables in a single ecosystem. In the context of scarce data and an incipient management structure, these findings are crucial to develop a coherent approach for fisheries management.

Influence of protogynous sex change on recovery of fish populations within marine protected areas.

Marine protected areas (MPAs) are increasingly implemented as a conservation tool worldwide. In many cases, they are managed adaptively: the abundance of target species is monitored, and observations are compared to some model-based expectation for the trajectory of population recovery to ensure that the MPA is achieving its goals. Most previous analyses of the transient (short-term) response of populations to the cessation of fishing inside MPAs have dealt only with gonochore (fixed-sex) species. However, many important fishery species are protogynous hermaphrodites (female-to-male sex-changing). Because size-selective harvest will predominantly target males in these species, harvesting not only reduces abundance but also skews the sex ratio toward females. Thus the response to MPA implementation will involve changes in both survival and sex ratio, and ultimately reproductive output. We used an age-structured model of a generic sex-changing fish population to compare transient population dynamics after MPA implementation to those of an otherwise similar gonochore population and examine how different features of sex-changing life history affect those dynamics. We examined both demographically open (most larval recruitment comes from outside the MPA) and demographically closed (most larval recruitment is locally produced) dynamics. Under both scenarios, population recovery of protogynous species takes longer when fishing was more intense pre-MPA (as in gonochores), but also depends heavily on the mating function, the degree to which the sex ratio affects reproduction. If few males are needed and reproduction is not affected by a highly female-biased sex ratio, then population recovery is much faster; if males are a limiting resource, then increases in abundance after MPA implementation are much slower than for gonochores. Unfortunately, the mating function is largely unknown for fishes. In general, we expect that most protogynous species with haremic mating systems will be in the first category (few males needed), though there is at least one example of a fish species (though not a sex-changing species) for which males are limiting. Thus a better understanding of the importance of male fish to population dynamics is needed for the adaptive management of MPAs.

Perception of subsistence hunters in Lower Madeira on the impact of the Santo Antônio Hydroelectric Power Plant

Brazil has one of the highest levels of biodiversity in the world, much of which is located in the Amazon region. The populations inhabiting this region guarantee their livelihood with natural resources, among which hunting stands out. The purpose of this study was to conduct a survey on the impacts caused by the Santo Antônio Hydroelectric Power Plant (HPP) to subsistence hunting downstream in Madeira River, Porto Velho-Rondônia. Interviews were conducted in eight communities downstream of the Santo Antônio HPP: São Carlos, Brasileira, Curicacas, Cuniã, Cavalcante, Agrovila, Nazaré, and Terra Caída. Data were collected through semi-structured questionnaires, from June to October 2019. Thirty-two hunters older than 18 were interviewed: 31 males and one female. Ten species were recorded: seven mammals, two birds, and one reptile. In relation to mammals, the species with the highest number of citations was Cuniculus paca, which was also the most cited hunting species among the three classes. The hunters’ preference for mammals is related to the availability and volume (quantity) of meat. These species have a long life cycle, with low demographic densities and relatively low reproductive capacities, making them more sensitive to unrestrained or irrational hunting. During the research, a reported decrease in abundance was recorded for eight of the ten species mentioned after the construction of the dam. The information collected in this study confirmed that the construction of the Santo Antônio HPP contributed directly to the decrease in abundance of target species, impairing subsistence hunting in the evaluated communities.

Spatial-seasonal variability of vertebrate assemblages in a Neotropical tidal flat: Recommendations for monitoring the potential impacts of port expansion

Our study aimed to understand the nekton biodiversity of a Neotropical tidal flat in southeastern Brazil (Araçá Bay) and to support its conservation, due to a potential port expansion, by determining: (1) the structure of the local assemblage of nekton (birds, fishes and turtles); (2) its spatial and seasonal variability; (3) potential processes explaining such variability; and (4) the impacts and monitoring measures related to port expansion. Araçá Bay has a high vertebrate richness (205 species, consisting of at least 126 fishes, 78 birds and one turtle species), two invasive fish species, 11 endangered species, a large abundance of target species in fisheries, and a high functional diversity in terms of life history and feeding habits. Mullets, mojarras, sardines and gobies dominate the fish assemblage, while the avifauna is mainly composed of herons and plovers. Green turtles (juveniles) were registered during high tides in all seasons. The low-tide bird and high-tide fish assemblages are spatially structured varying between the inner and the outer area of the flat. In tide pools, fish fauna varies according to bottom type. Juvenile fish predominate; fish assemblage varied according to recruitment and bird’s varied seasonally due to migration. The unique mosaic of habitats and the high productivity of the bay explain the high nekton diversity and make it a locally critical ecosystem for feeding, breeding, and growth. The port expansion would decrease the habitat diversity and productivity in the bay, negatively affecting nekton populations and their ecosystem services. We propose key aspects for nekton monitoring to mitigate port-related impacts.

Shifting perceptions of rapid temperature changes’ effects on marine fisheries, 1945–2017

AbstractClimate‐driven warming has both social and ecological effects on marine fisheries. While recent changes due to anthropogenic global warming have been documented, similar basin‐wide changes have occurred in the past due to natural temperature fluctuations. Here, we document the effects of rapidly changing water temperatures along the United States’ east coast using observations from fisheries newspapers during a warming phase (1945–1951) and subsequent cooling phase (1952–1960) of the Atlantic Multidecadal Oscillation, which we compared to similar recent observations of warming waters (1998–2017). Historical warming and cooling events affected the abundance of species targeted by fishing, the prevalence of novel and invasive species, and physical access to targeted species. Fishing communities viewed historical cooling waters twice as negatively as they did warming waters (72% vs. 35% of observations). Colder waters were associated with a decrease in fishing opportunity due to storminess, while warming waters were associated with the potential for new fisheries. In contrast, recent warming waters were viewed as strongly negative by fishing communities (72% of observations), associated with disease, reductions in abundances of target species, and shifts in distributions across jurisdictional lines. This increasing perception that warming negatively affects local fisheries may be due to an overall reduction of opportunity in fisheries over the past half century, an awareness of the relative severity of warming today, larger changes in American culture, or a combination of these factors. Negative perceptions of recent warming waters’ effects on fisheries suggest that fishing communities are currently finding the prospect of climate adaptation difficult.