Three ways to deliver a net positive impact with biodiversity offsets

Biodiversity offsetting is the practice of using conservation actions, such as habitat restoration, management, or protection, to compensate for ecological losses caused by development activity, including construction projects. The typical goal of offsetting is no net loss (NNL), which means that all ecological losses are compensated for by commensurate offset gains. We focused on a conceptual and methodological exploration of net positive impact (NPI), an ambitious goal that implies commitment beyond NNL and that has recently received increasing attention from big business and environmental nongovernmental organizations. We identified 3 main ways NPI could be delivered: use of an additional NPI multiplier; use of slowly developing permanent offsets to deliver additional gains after NNL has first been reached during a shorter offset evaluation time interval; and the combination of permanent offsets with partially temporary losses. An important and novel variant of the last mechanism is the use of an alternate mitigation hierarchy so that gains from the traditional third step of the mitigation hierarchy (i.e., onsite rehabilitation) are no longer be counted toward reduced offset requirements. The outcome from these 3 factors is that for the same ecological damage, larger offsets will be required than previously, thereby improving offset success. As a corollary, we show that offsets are NNL only at 1 ephemeral point in time, before which they are net negative and after which they become either NPI or net negative impact, depending on whether permanent offsets are combined with partially temporary losses or if temporary offset gains are combined with partially permanent losses. To achieve NPI, offsets must be made permanent, and they must achieve NNL during an agreed-upon offset evaluation period. An additional NPI-multiplier and use of the modified mitigation hierarchy will deliver additional NPI gains. Achieving NPI is fully conditional on prior achievement of NNL, and NNL offsets have been frequently observed to fail due to inadequate policy requirements, poor planning, or incomplete implementation. Nevertheless, achieving NPI becomes straightforward if NNL can be credibly reached first.     

Major shifts in Amazon wildlife populations from recent intensification of floods and drought

In the western Amazon Basin, recent intensification of river‐level cycles has increased flooding during the wet seasons and decreased precipitation during the dry season. Greater than normal floods occurred in 2009 and in all years from 2011 to 2015 during high‐water seasons, and a drought occurred during the 2010 low‐water season. During these years, we surveyed populations of terrestrial, arboreal, and aquatic wildlife in a seasonally flooded Amazonian forest in the Loreto region of Peru (99,780 km²) to study the effects of intensification of natural climatic fluctuations on wildlife populations and in turn effects on resource use by local people. Shifts in fish and terrestrial mammal populations occurred during consecutive years of high floods and the drought of 2010. As floods intensified, terrestrial mammal populations decreased by 95%. Fish, waterfowl, and otter (Pteronura brasiliensis) abundances increased during years of intensive floods, whereas river dolphin and caiman populations had stable abundances. Arboreal species, including, macaws, game birds, primates, felids, and other arboreal mammals had stable populations and were not affected directly by high floods. The drought of 2010 had the opposite effect: fish, waterfowl, and dolphin populations decreased, and populations of terrestrial and arboreal species remained stable. Ungulates and large rodents are important sources of food and income for local people, and large declines in these animals has shifted resource use of people living in the flooded forests away from hunting to a greater reliance on fish.     

Use of Fully Biodegradable Panels to Reduce Derelict Pot Threats to Marine Fauna

Fishing pots (i.e., traps) are designed to catch fish or crustaceans and are used globally. Lost pots are a concern for a variety of fisheries, and there are reports that 10 – 70% of deployed pots are lost annually. Derelict fishing pots can be a source of mortality for target and bycatch species for several years. Because continual removal of derelict gear can be impractical over large spatial extents, modifications are needed to disarm gear once it is lost. We tested a fully biodegradable panel with a cull or escape ring designed for placement on the sides of a crab pot that completely degrades into environmentally neutral constituents after approximately 1 year. This panel is relatively inexpensive, easy to install, and can be used in multiple fisheries. We used the blue crab (Callinectes sapidus) fishery as a test case because it is a large pot fishery and blue crab pots are similar to traps used in other pot fisheries. We had commercial fishers deploy pots with panels alongside standard pots in Chesapeake Bay (U.S.A.) to assess potential effects of our experimental pots on blue crab catch. We compared the number, biomass, and size of crabs captured between standard and experimental pots and evaluated differences in catch over a crabbing season (March–November) at five locations. There was no evidence that biodegradable panels adversely affected catch. In all locations and time periods, legal catches were comparable in abundance, biomass, and size between experimental and standard pots. Properly designed biodegradable panels appear to be a viable solution to mitigate adverse effects of derelict pots. Uso de Paneles Completamente Biodegradables para Reducir las Amenazas de Vasijas Abandonadas para la Fauna Marina     

Understanding Anglers’ Preferences for Fishing Tournament Characteristics and Policies

Saltwater fishing tournaments in the United States are generally not regulated nor are there different fishing regulations for tournament and nontournament anglers. Although much is known about those who participate in fishing tournaments in terms of their fishing motivations, attitudes, and characteristics, much less is known at the angler population level regarding their preferences for tournament opportunities. Using a stated preference choice model with hypothetical scenarios to simulate participation choices and understand preferences, study objectives were to identify angler preferences for various types of tournament fishing “products.” Four tournament policy characteristics were investigated: promotion of catch and release, bait restrictions, whether a percentage of the tournament entrance fee should go to support fishery management activities, and whether a tournament should be a nonprofit or profit-making venture. Three expectation attributes were inserted: tournament size, trip cost per day, and whether a tournament is family friendly. We sent seven different versions of the mail questionnaire to 1,633 anglers. Of 795 returns, 648 were used for estimating conditional logit models. Analysis indicated that a scenario with no management interventions was not most preferred. Anglers most preferred a conservation-oriented option that introduced additional management measures. Overall, scenarios with management interventions were more favored than the status quo situation (with no management interventions). Although respondents showed reluctance to adopt other management-related options, results generally indicated they were increasingly concerned with sustainability of fish stocks and potential conflicts between tournament and nontournament users and preferred tournament products that reflect these concerns.     

基于路网脆弱性的紧急情况下交通疏散诱导模型

为提高紧急情况下交通疏散速度,实现对疏散交通流的诱导,需要建立紧急情况下的交通流诱导模型。根据紧急情况下路网特性,提出路网脆弱性指标,并将其引入交通流诱导模型,对常态交通流诱导模型进行改进,得到基于路网脆弱性的紧急情况下交通疏散诱导模型,并用实测数据求解模型参数。分别用常态交通流诱导模型和文中的改进模型进行实例计算,结果表明,经过改进模型诱导之后,高流量和低流量路段相对减少,交通流在路网中的分布更均衡、达到系统最优的效果。对紧急情况下的交通流进行有效诱导,可提高疏散路网利用效率,加快应急交通疏散。     

基于系统动力学的安全生产监管有效性研究

为改善我国安全生产监管的效果,研究引入激励性监管措施后的安全生产监管效果。运用系统动力学(SD)建模方法,对比单用约束性监管措施的效果与综合运用约束性监管措施和激励性监管措施的效果。研究结果表明:单独使用约束性监管措施时,提高检查罚金和事故赔偿额,会使企业净收益、政府与企业的净收益总和增加。然而,综合使用约束性监管措施和激励性监管措施时,企业的净收益额增加,政府的净收益额减少,而企业与政府的净收益总额变化不大,但结合对事故负外部性的考虑,通常会使社会福利额外提高。     

Disentangling the causes of protected‐species bycatch in gillnet fisheries

Gillnet fisheries are widely thought to pose a conservation threat to many populations of marine mammals, seabirds, and turtles. Gillnet fisheries also support a significant proportion of small‐scale fishing communities worldwide. Despite a large number of studies on protected‐species bycatch in recent decades, relatively few have examined the underlying causes of bycatch and fewer still have considered the issue from a multitaxon perspective. We used 3 bibliographic databases and one search engine to identify studies by year of publication and taxon. The majority of studies on the mechanisms of gillnet bycatch are not accessible through the mainstream published literature. Many are reported in technical papers, government reports, and university theses. We reviewed over 600 published and unpublished studies of bycatch in which causal or correlative factors were considered and identified therein 28 environmental, operational, technical, and behavioral factors that may be associated with high or low bycatch rates of the taxa. Of the factors considered, 11 were associated with potential bycatch reduction in 2 out of the 3 taxa, and 3 factors (water depth, mesh size, and net height) were associated with trends in bycatch rate for all 3 taxa. These findings provide a basis to guide further experimental work to test hypotheses about which factors most influence bycatch rates and to explore ways of managing fishing activities and improving gear design to minimize the incidental capture of species of conservation concern while ensuring the viability of the fisheries concerned.     

Social cost‐benefit analysis of intensive versus traditional shrimp farming: A case study from India

This paper attempts a social cost‐benefit analysis of intensive versus traditional shrimp farming in West Bengal, India. Using primary data, the paper shows that although intensive shrimp farming yields high returns as compared to traditional shrimp farming, when the opportunity costs and environmental costs of shrimp farming, including disease risk, are accounted for, intensive shrimp farming loses its advantage. Sensitivity analysis shows that if the expected benefits were to fall short by 15% and costs rise by a similar proportion, intensive shrimp farmers would report higher losses than traditional shrimp farmers. Large traditional shrimp farmers continue to report positive net returns. These results are also most pronounced for small and marginal intensive shrimp farmers. Further, if the probability of disease risk is also accounted for, intensive shrimp farming reports significant losses whereas traditional shrimp farming in most cases shows positive net returns. In light of the high social costs and risks, this paper questions the rationale behind promoting intensive shrimp farming, especially among small and marginal holdings, as an income‐generating activity or poverty alleviation measure in the absence of an enabling environment. It suggests that policymakers need to factor in sustainability concerns and the local context when formulating policies to promote intensive shrimp farming.     

长江流域禁捕生态补偿政策绩效评价及影响因素分析——以湖北和贵州为例

渔民作为我国长江流域禁捕生态补偿政策的对象,渔民的满意程度是衡量禁捕生态补偿政策的重要指标。选取的研究地区是首批推行并完成禁捕生态补偿政策的贵州省赤水河流域和湖北省洪湖市,基于退捕渔民调研结果,先使用TOPSIS法的数学模型求出最优解,再进行障碍度计算,并对禁捕政策实施效果和相关影响因素进行了实证分析。结果表明：（1）关于禁捕生态补偿政策渔民评价的最优解,贵州省赤水河流域为0.45,绩效一般,湖北省洪湖市为0.27,对应的绩效水平为较差;（2）影响两个地区绩效评价的前三位主要因素是实施禁捕后,政府部门工作跟踪力度满意度（B₄）、生活水平满意度（D₂）、社会活动与社会地位满意度（E₂）。研究结论为评价禁捕生态补偿政策绩效提供一个可选分析框架,为其他地区提高禁捕生态补偿政策绩效提供参考依据。     

Total Factor Productivity Change in the New England Groundfish Fishery: 1964–1993

We develop estimates of total factor productivity (TFP) change in the New England groundfish fishery from 1964 to 1993, using a procedure similar to Squires' (1992, Rand J. Econom.23(2), 221–236) method, which extends standard TFP measurement by including the effect of fluctuations in stock abundance. The results indicate that TFP increased on average by 4.4% per year from 1964 to 1993. A higher average rate of increase occurred between 1964 and 1982, possibly due to new technologies (e.g., fishfinders). TFP declined at 0.33% annually from 1983 to 1993 due to stringent output and effort control measures.