Stock Recovery Research Articles

Timber stock recovery in a chronosequence of secondary forests in Southern Brazil: Adding value to restored landscapes

The Brazilian Atlantic forest is largely covered by secondary forests, mostly regenerated after the abandonment of patches previously used for shifting cultivation. A characteristic of these secondary forests is the significant timber volume from fast-growing species at ages as young as 30–40 years. In this study, we investigated changes that occur in timber production of secondary forest during the first 50 years of succession. We inventoried 82 plots (10 × 20 m) in a chronosequence ranging from 2 to 50 years since agricultural abandonment in four municipalities located in Santa Catarina State, Southern Brazil. Our results showed that commercial tree species have rapid recovery of richness, basal area and stem volume in naturally regenerating forests. Commercial species represent about 51 percent of tree diversity, with 9 out of 12 dominant species being commercial timber species, with a stem volume up to 155 m3 ha−1. Trees of commercial species with ≥15 cm in diameter are first observed after 20 years of succession, while trees ≥30 cm are found at 30 years of succession, and produce 126 m3 ha−1 of stem volume. We highlight Hyeronima alchorneoides, Miconia cabucu and Miconia cinnamomifolia, as fast-growing dominant species that produce timber quality ≥20 cm in diameter after 20 years of succession, with volume reaching 200 m3 ha−1 before 40 years of succession. We found that secondary forests are dominated by fast-growing and wood-producing species, with a rapid increase in timber stocks in the early stages of succession. These secondary forests are important biodiversity reservoirs in human-pressured landscapes, in addition to providing forest products and other ecosystem services. The management of secondary forests may be an alternative restoration approach that can accelerate the recovery of timber stocks, provide landscape diversity, and add more value to private forests.

Modeling the impacts of fishing regulations in a tropical Indian estuary using Ecopath with Ecosim approach

In this study, we measured the impacts of an effective fishing regulation on the sustainability of fisheries in Zuari estuary, a tropical estuary situated along western coast of India through an Ecosim approach. Ecosystem indicators for 2016 and 2031 (for each Ecosim scenario) were measured to compare and contrast the decadal changes in the status of the ecosystem between these two periods. Four different hypothetical fishing patterns were simulated to explore the best suited management scenario. The ecosystem indices of 2031 ecosystem were compared with that obtained for 2016 to evaluate the possible effects of fishing regulations. The functional groups showed a decline in their biomass when no fishing regulations are implemented (S1). The direct fishing effort reductions of all the fleets (S4) and ban/reduction of indiscriminate fishing fleets (S2-immediate ban and S3-gradual reduction) showed a more or less similar trend for recovery of fish stocks through diverse fisheries policies. A complete ban of indiscriminate fishing seems to slightly more advantageous than the direct reductions in the fishing effort for all the fleets in terms of stock recovery (130%), Q statistic (1.15), Shannon diversity (1.43), mean trophic level of ecosystem (2.98), mean trophic level of the catch (2.91) and fish catch in the gillnet fleet (200%). The simulations have also suggested that a complete control for mechanized fishing fleets will be the best possible management strategy for the recovery of fish stocks in the ecosystem.

Modeling and analysis of the effect of COVID-19 on the stock price: V and L-shape recovery

The emergence of the COVID-19 pandemic, a new and novel risk factor, leads to the stock price crash due to the investors’ rapid and synchronous sell-off. However, within a short period, the quality sectors start recovering from the bottom. A stock price model has been developed to capture the price dynamics during shock and recovery phases of such crisis. The main variable and parameter of the model are the net fund flow (Ψt) due to institutional investors, and financial antifragility (ϕ) of a company, respectively. We assume that during the crash, the stock price fall is independent of the ϕ. We study the effects of shock length (TS) and ϕ on the stock price during the crisis period using the Ψt obtained from both the synthetic fund flow data and real fund flow data. We observed that the possibility of recovery of stock with ϕ>0, termed as quality stock, decreases with an increase in TS beyond a specific period. A quality stock with higher ϕ shows V-shape recovery and outperform others. The TS and recovery period of quality stock are almost equal in the Indian market. Financially stressed stocks, i.e., the stocks with ϕ<0, show L-shape recovery during the pandemic. The stock data and model analysis show that the investors, in the uncertainty like COVID-19, invest in the quality stocks to restructure their portfolio to reduce the risk. The study may help the investors to make the right investment decision during a crisis.

Harnessing scientific and local knowledge to face climate change in small-scale fisheries

Small-scale fisheries in developing regions are particularly vulnerable to climate change, but the assessment of climate-induced changes and impacts are often hampered by the data poor-situation of these social-ecological systems. Based on 40 years of scientific and local ecological knowledge, we provide a coherent narrative about the effects of a marine hotspot of climate change on a small-scale fishery across different geographical and temporal scales. We applied a mixed-methods approach to assess biophysical changes, social-ecological impacts, and the incremental spectrum of actions implemented at multiple levels to increase the adaptive capacity of a small-scale clam fishery. The warming hotspot here analyzed was the fastest-warming region in the South Atlantic Ocean. Long-term changes in wind intensity and direction were also noticeable at a regional scale. Both sea surface temperature and winds showed a clear shifting pattern in the late 1990 s. These climate-related stressors determined ecosystem and targeted population changes (e.g. clam mass mortalities, slow stock recovery rates after ecological shocks, habitat narrowing), and favored harmful algal bloom-forming organisms. Climate-induced drivers also affected the human component of the social-ecological system, preventing fishers from securing a fulltime livelihood and limiting the fishery economic potential. Adaptive responses at multiple levels provided some capacity to address climate change effects, and transformative pathways are being taken to adapt to climate-induced changes over the long-term. Transformative changes were fostered by the local perception of environmental change, shared narratives, sustained scientific monitoring programs, and the interaction between knowledge systems, facilitated by a bridging organization within a broader process of governance transformation. The combination of autonomous adaptations (based on linking social capital and fishery leaders agency) and government-led adaptations were essential to face the challenges imposed by climate change. Our results serve as a learning platform to anticipate threats and envision solutions to a wide range of small-scale fisheries in fast-warming regions worldwide.

Economic Impact of Eliminating the Fuel Tax Exemption in the EU Fishing Fleet

The EU-27 fishing fleet consumed 2.02 billion liters of fuel to catch 4.48 million tons of fish, valued at €6.7 billion in 2018. The profitability of the EU fishing fleet shows an increasing trend, partly due to the improvements in the energy efficiency and recovery of fish stocks in the North-east Atlantic. Fuel is one of the main expenses fishing fleets have, and therefore, their economic performance remains highly dependent on the fuel price, even if they benefit from a fuel tax exemption. The adoption of the European Green Deal, the revision of the Energy Taxation Directive (ETD), the ongoing World Trade Organization (WTO) negotiation to prohibit harmful fisheries subsidies, and general public opinion are putting pressure to eliminate this tax exemption. This analysis investigates the impacts of the potential elimination of the fuel tax exemption across the different EU fishing fleets and it is discussed to what extent the small-scale, large-scale and distant-water fleets could be affected. This analysis is useful to inform policy-makers and stakeholders on the consequences of the potential elimination of the fuel tax exemption, as well as to discuss potential measures to mitigate the socioeconomic impacts arising from this eventual change in the current regulatory framework.

Factors determining spawning run dynamics and current state of sockeye salmon &lt;i&gt;Oncorhynchus nerka&lt;/i&gt; resources in the Kamchatka River

Hydrological regime and morphodynamics of the outlet part of the Kamchatka River, dynamics of mixing zone, patterns of juvenile Pacific salmon distribution and migration in the coastal waters of Kamchatsky Gulf in the zone of operating trap nets were analyzed on the results of complex field works prowided in summer period in 2018–2019; fishing and specifics of sockeye salmon spawning run in the river was described. In the course of analyzing the entire complex of available long-term data, an assessment of the likely impact of some key factors on the dynamics of anadromous migration of sockeye salmon in the Kamchatka River was made; biological statistics of spawners and current state of reproduction of this stock was demonstrated. It is found, that natural environmental factors, neither abiotic nor biotic (including fish health as population internal factor), could not cause disturbance of sockeye salmon spawning run dynamics in the Kamchatka River in recent years. Smoller body size and physiological imperfection of the spawners before the anadromous migration due to effects of high number of pink salmon in recent years are suggested to be the most likely cause of spawning run delay in late sockeye salmon morph. Regime of commercial use of the stock and general increasing pressure on the spawning stock by coastal fisheries are demonstrated to be the strongest outer factors to affect modern state of the resources and sockeye salmon population structure in the Kamchatka River, causing permanent escapement deficiency on spawning grounds in the river basin (first of all in the late morph), and also infact lead to disballance between different subpopulation groups in the composition of the stock. Recommendations in order to provide recovery and sustainable level of the Kamchatka River sockeye salmon stock are given in the perspective of more efficient commercial use of the stock next several years; highlights for further researches are outlined.

Linking Scales of Life-History Variation With Population Structure in Atlantic Cod

It is increasingly recognised that sustainable exploitation of marine fish requires the consideration of population diversity and associated productivity. This study used a combination of genotypic screening and phenotypic traits to define the scale of population structuring in Atlantic cod inhabiting the northern North Sea (ICES Sub-division 4a) and Scottish west coast (ICES Division 6a). The genetic analysis indicated an isolation by distance pattern with an even finer scale structuring than previously reported, that persisted over a decade and between feeding and spawning seasons. Spatial variation in phenotypic traits reflected genetic variation with cod maturing later and at a larger size near the Viking Bank in 4a. The identified population structuring provides an explanation for differences in historic changes in maturation schedules and the temperature exposure recorded in previous electronic tagging studies. The study also highlights how the mismatch between stock divisions and population units is leading to a misunderstanding about stock recovery.

Aboveground Biomass and Carbon Accumulation 19 Years Post-Windthrow and Salvage Logging

Natural disturbances shape forest ecosystem characteristics, including carbon storage and structure. Often, natural disturbances are compounded with anthropogenic disturbances, which may alter the trajectory of forest carbon stock recovery. Heterogeneous levels of disturbance severity in compound disturbance events add an additional layer of complexity. This paper examines the effect of a moderate-severity wind disturbance and subsequent salvage logging on forest biomass and carbon stock recovery over 19 years. We investigate the recovery of aboveground tree biomass following a wind disturbance and salvage logging and examine the role of wind disturbance severity on biomass accumulation rates. We use pre-disturbance, 3 years post-wind disturbance and 19 years post-wind disturbance measurements of tree biomass across two adjacent sites at Natchez Trace State Forest for Site A and Site B in east central Tennessee. We found no significant difference in the carbon storage at Site A (pre = 92 MgC/ha; 19 years post-disturbance = 83 MgC/ha) or Site B (pre = 66 MgC/ha; 19 years post-disturbance = 67) when comparing the pre-disturbance level of aboveground tree carbon storage with the 19-years post-disturbance levels. Furthermore, we found no evidence that salvage logging reduced the rate of live tree carbon accumulation. The corresponding rates of mean annual carbon accumulation (MgC/ha) are as follows: Site A Unsalvaged (1.07), Site A Salvaged (1.25) and Site B Salvaged (2.02). Contrary to our prediction, greater wind damage severity was weakly associated with higher rates of biomass accumulation (R2 = 0.17). While we found no negative effect of salvage logging on the aboveground tree carbon accumulation rate, salvage logging alters other carbon pools, including coarse woody debris. Salvage logging did not reduce the rate of carbon stock recovery, and a higher wind disturbance severity was associated with a greater rate of carbon stock recovery.

The sources and prevalence of anthropogenic noise in Rockfish Conservation Areas with implications for marine reserve planning

Underwater noise pollution is a recognized threat to marine life. In British Columbia, Canada, Pacific rockfish (Sebastes spp.) were historically overfished, prompting the establishment of Rockfish Conservation Areas (RCAs). However, there are no restrictions prohibiting vessel transits in RCAs. We hypothesized that RCAs do not protect rockfish from sub-lethal harm from noise. We compared noise levels at three RCAs with adjacent unprotected reference sites from August 2018–June 2019. While RCAs had lower levels of noise overall than reference sites, this trend was inconsistent; some RCA sites had higher levels of noise during certain time periods than non-RCA sites. A vessel noise detector was the best predictor of noise level over three frequency bands (20–100 Hz, 100–1000 Hz, 1–10 kHz), and predicted sound levels which could mask rockfish communication. We conclude that RCAs do not reliably protect rockfish from noise pollution, and recommend further study into potential impacts on stock recovery.

Growth and mortality analyses of the white shrimp Penaeus schmitti (Decapoda: Penaeidae) in Sepetiba Bay, Brazil: An exploited data-deficient species

Penaeus schmitti is fisheries resource explored throughout the area where it occurs and is one of the most important penaeid in terms of fishery biomass in Brazil. The current conservation state of P. schmitti in Brazil is worrisome because inserted in the category of Insufficient Data in the Red book of Crustaceans of Brazil. The goals of this study were to estimate growth and mortality rates of P. schmitti in Sepetiba Bay, Rio de Janeiro State, southeastern Brazil, and to assess the effect of fishing on the population. Monthly samples were collected during one year through regional artisanal fishery. Growth was assessed through modal analysis according to von Bertalanffy growth function (VBGF). Instantaneous mortality rates Z (total), M (natural), F (fishing) and the exploitation rates (E) were estimated. Total mortality (Z) was estimated by length-converted catch curves and M was based on parameters of the VBGF. Growth parameters differed significantly between sexes and a single curve could not be applied to both sexes. Females of P. schmitti, were larger and grow faster (high k value) but were less abundant than males. Instantaneous mortality rates were similar for males and females. Females were vulnerable to fishing activities at three months of age, males at four months of age. The exploitation rate of the species was greater than 50%, highlighting a possible overfishing of the species. Limiting access to nursery areas of juveniles would be a good strategy for stock recovery.

Evaluating the social and ecological effectiveness of partially protected marine areas.

Marine protected areas (MPAs) are a primary tool for the stewardship, conservation, and restoration of marine ecosystems, yet 69% of global MPAs are only partially protected (i.e., are open to some form of fishing). Although fully protected areas have well‐documented outcomes, including increased fish diversity and biomass, the effectiveness of partially protected areas is contested. Partially protected areas may provide benefits in some contexts and may be warranted for social reasons, yet social outcomes often depend on MPAs achieving their ecological goals to distinguish them from open areas and justify the cost of protection. We assessed the social perceptions and ecological effectiveness of 18 partially protected areas and 19 fully protected areas compared with 19 open areas along 7000 km of coast of southern Australia. We used mixed methods, gathering data via semistructured interviews, site surveys, and Reef Life (underwater visual census) surveys. We analyzed qualitative data in accordance with grounded theory and quantitative data with multivariate and univariate linear mixed‐effects models. We found no social or ecological benefits for partially protected areas relative to open areas in our study. Partially protected areas had no more fish, invertebrates, or algae than open areas; were poorly understood by coastal users; were not more attractive than open areas; and were not perceived to have better marine life than open areas. These findings provide an important counterpoint to some large‐scale meta‐analyses that conclude partially protected areas can be ecologically effective but that draw this conclusion based on narrower measures. We argue that partially protected areas act as red herrings in marine conservation because they create an illusion of protection and consume scarce conservation resources yet provide little or no social or ecological gain over open areas. Fully protected areas, by contrast, have more fish species and biomass and are well understood, supported, and valued by the public. They are perceived to have better marine life and be improving over time in keeping with actual ecological results. Conservation outcomes can be improved by upgrading partially protected areas to higher levels of protection including conversion to fully protected areas.

Responses of a pelagic fish community to reduced fishing pressure in the central Bering Sea

Ecosystem-based fishery management (EBFM) requires minimizing the risk of irreversible change to a natural assemblage of species. Because pelagic fisheries modify the biotic community rather than the physical environment and often target migratory species, the pelagic community can be expected to respond quickly after fishing pressure is reduced. We monitored the pelagic zooplanktivore community over 4 decades in the central Bering Sea before and after the closures of large-scale pelagic fisheries. We found a quick and steep change in the pelagic fish community structure after fishing pressure was reduced, which reflected increased abundance of salmon species; however, walleye pollock stocks, one of the most valuable fisheries resources in this area, have not recovered. A lower population growth rate might contribute to the slow recovery of pollock stocks. Long-term ecosystem monitoring of fishing grounds and surrounding ecosystems will be required for successful implementation of EBFM of pelagic fish stocks.

PRELIMINARY STOCK ASSESSMENT RESULTS FOR SHAD IN AZOV-BLACK SEA BASIN IN TERMS OF DATA LUCKING (2007-2020)

Black-azov sea shad Alosa immaculate (Bennett, 1835) stock assessment performed by trending model CMSY in terms of data lucking for period 2007–2020 in R. Model results showed current stock status in biological safe zone (B2020 = 2291 t, BMSY = 1855 t, B2020/BMSY = 1,23) with signs of minor overexploitation by fishing mortality (F2020 = 0,35, FMSY = 0,28, F2020/FMSY = 1,25). Obtained stock biomass estimates shows minor Black-Azov sea shad stock recovery evidence in period 2007–2020. Evidence of light population fishery overexploitation after 2018 are found, perhaps, was caused by IUU-fishery. Paper results underline to eliminate and regulate shad illegal, unreported, unregistered fishery in Azov-Black sea basin

Spatial distribution of six managed tree species is influenced by topography conditions in the Central Amazon

In tropical forests, the spatial distribution of trees may present random, uniform, or grouped patterns that can simultaneously be affected by site and species characteristics. In Central Amazon, topographic gradients and soil water levels drive differences in tree species distribution and in forest dynamics at local scales. Knowing this kind of information can be useful for a forest manager to plan harvesting operations considering the microhabitat preference of merchantable species to reduce the disturbances caused by logging activities. Thus, the spatial variation of tree species is an important information to be considered to support the planning process of forest logging. The present study aims to evaluate the spatial distribution pattern of six species and analyze the relationship between the topography and the population densities and stem size of those species. The study was carried out in a forest production compartment managed by a private company located in the municipality of Silves, state of Amazonas, Brazil. The spatial pattern of the six species was characterized by Ripley's K function. Spatial distribution of diameter at breast height (DBH) and tree density based on kernel incidence calculation were evaluated for topographic classes of slope, elevation, and distance from streams, which were mapped using geographic information systems (GIS). The means of DBH and density of each species were compared among topographic classes by ANOVA and Tukey's test. The results demonstrated the predominance of the aggregate distribution pattern for the six species up to 1105 m (p < 0.01). The tree species Minquartia guianensis Aubl., Protium puncticulatum J.F.Macbr, Manilkara elata (Allemão ex Miq.) Monach, and Caryocar glabrum Aubl. Pers showed an increase in the tree density as the distance from the streams and elevation increased, standing spatially incident on plateaus. Kernel densities of Dinizia excelsa Ducke and Goupia glabra Aubl. were higher closer to streams. The DBH averages followed similar trends of population density for M. guianensis, M. elata, and C. glabrum, and the opposite pattern for D. excelsa, which presented larger individuals in less densely populated areas. P. puncticulatum and G. glabra mean DBH distribution was not affected by the topographic variables analyzed. Topography-related variables showed effects on variations of density and tree size, suggesting that species may be spatially sensitive to the habitat variability available in the study area. In view of logging planning, spatial distribution must be considered in decisions related to cutting down trees and maintenance of remaining trees, especially because some species are more aggregated in smaller scales. Moreover, as topographic variations affect the spatial distribution of size and density, the timber yield will vary spatially in the area, bringing implications for planning logging intensities, roads, skid trails and forest operations. Finally, the procedures and information generated in this study can be reproduced and applied to other species and managed areas to support the planning toward minimizing impacts on the spatial structure of commercial species, as well as to increase the chances of future stock recovery of managed forests in the Amazon.

Can no‐till restore soil organic carbon to levels under natural vegetation in a subtropical and tropical Typic Quartzipisamment?

AbstractSandy soils are widely distributed in Brazil and occur in most states. However, they have serious limitations for agricultural use due to low natural fertility, low water retention capacity, low resilience, and high susceptibility to erosion. Management of these soils through a no‐till (NT) system following its basic principles (i.e., elimination of plowing, diversification of crop rotation, retention of crop residues, and maintenance of permanent soil cover) is a practice that can restore the soil organic carbon (SOC) stock, and restore productivity and economic viability of these soils. We hypothesized that: (a) we can recover the carbon (C) stock in Typic Quartzipisamment in subtropical and tropical climates to the level of native vegetation; (b) the adoption of NT during the initial phase, in conjunction with intensive cropping systems with high plant biomass input, is an efficient strategy to recover SOC in Typic Quartzipisamment soils; and (c) long‐term NT (over 20 years—the maintenance phase), and low/medium input of plant biomass, is an efficient strategy for SOC recovery in Typic Quartzipisamment soils. Thus, the present study aimed at assessment of the recovery of SOC stocks in soil profile (0–1.0 m depth) in a Typic Quartzipisamment in subtropical and tropical climates, in comparison with the neighboring soil under native vegetation (NV). The sites selected for this study are located in two Brazilian grain‐producing regions: (a) Manoel Viana City—Rio Grande do Sul State (MV—site 1) that represents the subtropical climate condition, and (b) Luiz Eduardo Magalhães City—Bahia State (LEM—site 2), which represents the tropical climate. Soil samples were collected from soil profile for 0–1.0 m depth. At site 1, the predominant crop rotation over the years was wheat/soybean/oats + forage turnip/soybean. At site 2, the crop rotation includes cultivation in two periods designated as the crop and off‐seasons, and the succession consisted of soybean/Brachiaria/cotton/millet/soybean/maize‐Brachiaria. In both sites, soils under the neighboring NV were also sampled. SOC content was determined by the dry combustion method using an elemental C and N analyzer. Soil C stock was calculated based on the equivalent soil mass. Approximately 31 and 23% of the SOC stock was stored in the surface at 0–0.20 m, compared with 69 and 77% in 0.20–1.0 m layer of a Typic Quartzipisamment with high and low/medium input of crop residues, respectively. The Typic Quartzipisamment with low/medium input of crop residues fully recovered the stock of C in the surface soil layer (0–0.05 m). The Typic Quartzipisamment with high input of crop residues fully recovered the stock of C in the cultivated (0–0.20 m) and also in deeper soil layers (0–0.40 m). Thus, adoption of NT associated with intensification of cultivation systems and high addition of biomass‐C is an effective strategy for C restoration in a Typic Quartzipisamment, while also playing a crucial role in restoring ecosystem productivity, soil quality, and environment.

The influence of catch-and-release on mortality of Salminus brasiliensis (Cuvier, 1816).

Catch-and-release (CR) angling has been used to assist management programs seeking to promote the conservation and recovery of some recreational fish stocks by decreasing mortality from fishing. However, without appropriate fish handling, this activity may cause damage and injuries to individual fish, causing mortality. Therefore, CR should be allowed under some circumstances that ensure higher rates of survival to achieve the goals of the conservation measures. Thus, we experimentally tested the CR effects on dourado (Salminus brasiliensis) by comparing caught-and-released fish (CR fish) with uncaught fish (control fish) in a pond and estimating individual mortality rates related to seven air exposure times (AET: 120 s, 240 s, 360 s, 480 s, 600 s, 720 s and 840 s). We also determined a safe limit for fish handling and investigated the length and weight gain variations. We found that an increase in AET affects fish survival and that the limit of handling time for this species was 546 s; after this threshold, the individual probability of death exceeds 5%. The length and weight gain of CR fish did not differ significantly from the control fish. We believe that CR is efficient for S. brasiliensis because it does not significantly impair their organic growth and causes little or no mortality if handling is performed properly; thus, it could be employed to assist conservation programs.

Using Harvest Slot Limits to Promote Stock Recovery and Broaden Age Structure in Marine Recreational Fisheries: A Case Study

AbstractFish populations with broad age distributions are expected to have higher reproductive capacity than age‐truncated populations because of the disproportionate contributions of older fish. Harvest slot limits, an expected means of ameliorating age truncation, are modeled for Tautog Tautoga onitis in an overfished population subunit that is experiencing overfishing. Tautog, currently managed with a 40‐cm minimum size limit (MSL), is a candidate species for slots because it is relatively long‐lived and slow‐growing, with low discard mortality. We evaluated changes in biomass and abundance at age relative to management with the current MSL regulations using a forward population simulation model for four slots: 35–45 cm (small–wide), 38–42 cm (small–narrow), 40–50 cm (large–wide), and 43–47 cm (large‐narrow), inclusive of lower and upper length limits. Angler behavioral responses were evaluated at 0, 10, and 20% noncompliance with the upper slot limit. The biomass and number of fish removed were reduced with harvest slot limit management relative to the MSL, but because the harvest was redirected to smaller fish the reduction in numbers removed was not as large as the reduction in biomass removed. Slot limits broadened the age structure within 10 years by reducing fishing mortality on extant fish. Median spawning stock biomass (SSB) recovered more quickly in three of the slots than with MSL regulation (3–6 years to reach SSB associated with a fishing mortality that yields 30% spawners per recruit as compared to 9 years with MSL management). We concluded that harvest slot limits can broaden age structure and restore biomass in overfished fisheries, but they should be evaluated when managing coastal fisheries as a reduction in biomass removed is required.

Mitigating seafloor disturbance of bottom trawl fisheries for North Sea sole Solea solea by replacing mechanical with electrical stimulation.

Ecosystem effects of bottom trawl fisheries are of major concern. Although it is prohibited to catch fish using electricity in European Union waters, a number of beam trawlers obtained a derogation and switched to pulse trawling to explore the potential to reduce impacts. Here we analyse whether using electrical rather than mechanical stimulation results in an overall reduction in physical disturbance of the seafloor in the beam-trawl fishery for sole Solea solea. We extend and apply a recently developed assessment framework to the Dutch beam-trawl fleet and show that the switch to pulse trawling substantially reduced benthic impacts when exploiting the total allowable catch of sole in the North Sea. Using Vessel Monitoring by Satellite and logbook data from 2009 to 2017, we estimate that the trawling footprint decreased by 23%, the precautionary impact indicator of the benthic community decreased by 39%, the impact on median longevity of the benthic community decreased by 20%, the impact on benthic biomass decreased by 61%, and the amount of sediment mobilised decreased by 39%. The decrease in impact is due to the replacement of tickler chains by electrode arrays, a lower towing speed and higher catch efficiency for sole. The effort and benthic physical disturbance of the beam-trawl fishery targeting plaice Pleuronectes platessa in the central North Sea increased with the recovery of the plaice stock. Our study illustrates the utility of a standardized methodological framework to assess the differences in time trends and physical disturbance between gears.

Comparing forest carbon stock losses between logging and wildfire in forests with contrasting responses to fire

Disturbance plays an important role in determining whether forests are carbon sinks or sources. Logging and wildfire are common widespread disturbances known to significantly reduce carbon stocks in carbon rich forests, such as, the tall forests of south-eastern Australia. Most tall forests in south-eastern Australia are dominated by globally unique resprouting Eucalypts that experience limited mortality after high severity wildfire. However, the most carbon dense forests in the region are dominated by non-resprouting Eucalypts that, like many other species associated with carbon dense forests around the world, experience stand replacement after high severity wildfire. We used space-for-time surveys to measure how above ground carbon stocks change with time since logging and time since wildfire in resprouting and non-resprouting Eucalypt forests in south-eastern Australia. Logging reduced above ground carbon stocks much more than wildfire in both forest types. Carbon stock losses caused by wildfire were more substantial in non-resprouting forests than resprouting forests, which experience only minor losses after wildfire. The recovery of carbon stocks after wildfire began to asymptote after approximately 40 years but increased almost continuously with time since logging in both forest types. Carbon stock losses associated with logging represent a much greater departure from natural disturbance in resprouting forests, because wildfire causes relatively little carbon loss in resprouting forests compared to non-resprouting forests. This analysis highlights the need to consider specific biological responses when assessing forest carbon stock losses associated with disturbance. Consideration of these dynamics is essential in addressing carbon stock risk mitigation.

Pattern of forest recovery and carbon stock following shifting cultivation in Manipur, North-East India.

Shifting cultivation has resulted in large-scale deforestation and forest degradation in the tropics; however the abandoned fallows are known to have high potential for carbon capture. The paper is an attempt to determine the forest recovery patterns following shifting cultivation by evaluating the tree species composition, diversity and abundance with respect to topographical factors in Manipur, India. We also used ordination analysis to understand the change in species composition with regard to environmental variables. The living woody biomass carbon of each fallow was quantified, and the factors affecting the recovery of carbon stock along an increasing fallow gradient was assessed. Our results showed that the species richness and basal area recovered relatively with time since abandonment, and the north-facing lower elevation fallow sites displayed higher species richness and stem density than those in higher elevations. Environmental variables had no impact on the regeneration of Elaeocarpus floribundus Blume and Castanopsis hystrix Hook. f. & Thomson ex A. DC. which suggests that they may be capable of effective restoration of degraded forest areas. As these species appear naturally in the forests, it would facilitate quicker rehabilitation and reinstate the soil nutrients making the soil reusable in a short term. We also found that fallow age plays a vital role in recovering above-ground biomass carbon from living woody species followed by the aspect of the site. The total living woody biomass carbon ranged from 0.98 Mg ha-1 in 5 years fallow to 142.58 Mg ha-1 in 20 years fallow. The above-ground biomass carbon recovery of the oldest fallow was 39% to 40% of the reference undisturbed forest and the estimated time for the shifting cultivation fallows to reach that of the undisturbed forest level was approximately 39 years to 41 years.