基于渔港抽样调查南海不同捕捞方式CPUE比较分析

本研究基于2016年对南海三省区的14个沿海主要渔港的连续4个季节抽样调查(共计5256航次,抽样总功率达到89.2×10~4 kW),以kg?kW~(-1)?d~(-1)作为CPUE(Catch per unit effort,单位捕捞努力量渔获量)标准化后的单位,对南海9种捕捞作业类型渔船的CPUE进行了比较分析。结果显示,CPUE_(围网)CPUE_(双拖)CPUE_(刺网)CPUE_(罩网)CPUE_(张网)CPUE_(单拖)CPUE_(虾拖)CPUE_(笼壶)CPUE_(钓具)。不同捕捞作业类型CPUE随渔船功率段的变化而不同,CPUE峰值数及其所对应的最优功率段(渔获率最高的功率段)也有差异,单拖和虾拖渔船的CPUE随渔船功率的变化具有1个CPUE峰值点,最优功率段分别为(200～250) kW(CPUE=8.6 kg?kW~(-1)?d~(-1))和(150～200) kW(CPUE=5.0 kg?kW~(-1)?d~(-1));围网、双拖、钓具和刺网渔船的CPUE随渔船功率的变化有2个CPUE峰值点,对应的最优功率段分别为(200～250)kW(CPUE=47.7kg?kW~(-1)?d~(-1))、(350～400)kW(CPUE=16.8kg?kW~(-1)?d~(-1))、(50～100)(CPUE=2.9 kg?kW~(-1)?d~(-1))和(0～50) kW(CPUE=6.9 kg?kW~(-1)?d~(-1))。罩网渔船CPUE随功率段变化有3个峰值点,最优功率段为(0～50) kW(CPUE=7.0 kg?kW~(-1)?d~(-1))。不同捕捞作业类型CPUE季节变化表现:围网CPUE均值在春季最高,单拖、双拖、罩网、钓具和笼壶在夏季最高,张网在秋季最高,刺网和虾拖在冬季最高。     

广东建设社会主义新农村着力点探讨

建设广东社会主义新农村是一个惠及广东4000多万农民的系统工程。建设的着力点是科学地利用广东优越的自然资源、充足的财力、产业梯度转移区位优势和农业产业化经营的典型范式;充分发挥各级党委、政府的主导作用,千方百计调动建设主体——广大农民群众的积极性和主动性;选优配强“两委”班子,形成民主管理新机制;积极创建和培育农民专业合作经济组织,大力发展农业产业化经营;统筹区域、城乡发展规划,实现产业梯度转移等。     

MEY = MSY

It has been generally accepted for more than half a century that the fishing sector stood to gain from managing fisheries at the effort level producing maximum economic yield (MEY) rather than at the higher effort level producing maximum sustainable yield (MSY). However, the acceptance is built on evaluating only the revenue and cost structure for the fishing fleet, not for the overall fishing sector including processing, distribution and marketing of fish products. Considering these links of the fish value chain moves the MEY-level closer to, but slightly below the MSY-level. For society as a whole, this means that MSY is the more appropriate target reference level.     

The legacy of past disturbance: Chronic angling impairs long-term recovery of marine epibenthic communities from acute date-mussel harvesting

Two major concerns affect the way we perceive impacts: first, no ecosystem can still be considered pristine and second, stressors may interact. Untangling the effects of broad-scale anthropogenic stressors is complicated as appropriate unimpacted areas at relevant scales are usually unavailable for contrast with impacted regions. Although the perfect study design in the traditions of small-scale manipulative experiments may not always be possible, many human impacts and the mechanisms associated with ecosystem responses have been highlighted in literature allowing contrasting predictions on expected patterns to be tested. We applied such an approach to the Marine Protected Area of Bergeggi (Ligurian Sea, NW Mediterranean). Our study aimed at assessing the effects of recreational angling (a presumed chronic stress) on the recovery of epibenthic communities following historical date-mussel harvesting (an extreme disturbance) by making and testing alternative predictions on the structure of epibenthic communities that should be apparent depending on the importance of specific mechanisms. Effects of date-mussel harvesting were still visible 20 years after its cessation, mostly because recovery is hampered by persistent sea-urchin grazing. We hypothesized that fish biomass removal by angling favours high sea urchin abundance. Based on these premises, we assembled information on angling pressure, sea urchin abundance and substratum cover by different trophic guilds to test our predictions. Our study indicates that the interaction between date-mussel harvesting and angling produced a shift, from autotrophic-dominated to consumer-dominated communities as a consequence of cascading trophic effects. Such an outcome implies that chronic recreation fishing pressure is blocking recovery in locations previously impacted by date-mussel harvesting. Testing predictions proved efficient in describing the interaction among stressors when system history is known and represents a valuable approach to provide scientifically sound insight for improved conservation management.     

Global fishery dynamics are poorly predicted by classical models

Fisheries dynamics can be thought of as the reciprocal relationship between an exploited population and the fishers and/or managers determining the exploitation patterns. Sustainable production of protein of these coupled human‐natural systems requires an understanding of their dynamics. Here, we characterized the fishery dynamics for 173 fisheries from around the globe by applying general additive models to estimated fishing mortality and spawning biomass from the RAM Legacy Database. GAMs specified to mimic production models and more flexible GAMs were applied. We show observed dynamics do not always match assumptions made in management using “classical” fisheries models, and the suitability of these assumptions varies significantly according to large marine ecosystem, habitat, variability in recruitment, maximum weight of a species and minimum observed stock biomass. These results identify circumstances in which simple models may be useful for management. However, adding flexibility to classical models often did not substantially improve performance, which suggests in many cases considering only biomass and removals will not be sufficient to model fishery dynamics. Knowledge of the suitability of common assumptions in management should be used in selecting modelling frameworks, setting management targets, testing management strategies and developing tools to manage data‐limited fisheries. Effectively balancing expectations of future protein production from capture fisheries and risk of undesirable outcomes (e.g., “fisheries collapse”) depends on understanding how well we can expect to predict future dynamics of a fishery using current management paradigms.     

青饲切碎机动刀片刃口的受力分析

通过对PCCⅣ15．0S型青饲切碎机动刀片刃口的受力分析，探讨转角口与滑切角τ、推挤角x、压力T、滑切力N和阻力p的关系；这项工作对动刀片刃口形状的设计和磨损规律的研究具有一定的指导意义。     

Mass mortality of common eiders (Somateria mollissima) in the Dutch Wadden Sea, winter 1999/2000: starvation in a commercially exploited wetland of international importance

Mass mortality of common eiders (Somateria mollissima) was observed in winter 1999/2000 in the Dutch Wadden Sea. Approximately 21,000 common eiders died. Dissected birds were severely emaciated and 94% were infected with the acanthocephalan parasite Profilicollis botulus. Green shore crabs (Carcinus maenas), intermediate hosts of the parasite, were slightly more ‘available’ than in other years, but parasite infections in the eiders were close to normal. Few eiders were oiled (5%), there were no toxicological, bacteriological, or virological explanations for the observed mortality.In the Wadden Sea, a wetland of international importance, mussel (Mytilus edulis) cultures occur in sublittoral areas, while mechanical cockle (Cerastoderma edule) fisheries are licensed annually after evaluation of available resources. The wintering eiders in 1999/2000 required c. 3.1 million kg ash-free dry mass, while information on mussel and cockle stocks (irrespective of accessibility and profitability) suggested a resource 4.7× the requirement of common eiders only. Food shortage is suggested to have caused the observed mortality, involving both principal (mussels and cockles) and secondary (Spisula) prey.Winter census reports showed shifts in wintering distribution of common eiders in the 1990s, indicating the utilisation of Spisula in the North Sea in poor food years in the Wadden Sea. Following particularly intense fisheries in summer 1999, attempts to feed on Spisula in winter 1999/2000 failed. It is hypothesised that overfishing of mussels and cockles in the Wadden Sea in the early 1990s resulted in structurally reduced food resources, contractions of the foraging area of common eiders, and increased use of secondary prey in the North Sea.     

福建省近期捕捞力量和捕捞作业结构的调整

分别对福建省在福建近海捕捞渔业及其五种主要捕捞作业的最大持续产量和最大持续捕捞力量进行估算，并在估算值的基础上，结合目前渔业资源结构变化趋势及福建近海渔业的实际情况，确定2005年之前福建省近海的捕捞力量和捕捞作业结构的调整方案，调整结果为：总捕捞力量由1998年的标准机施总功率3084460kW削减至1668940kW；其中定置渔业自然功率由1998年的202860kW削减到100136kW；拖网渔业由1474764kW削减到801091kW；灯围61645kW提高到100136kW，刺网渔业由449680kW削减到442269kW；钓渔业由67423kW提高到83447kW；其它作业由35126kW提高到141861kW。     

Recent evolution of the fishing exploitation in the Thau lagoon, France

Fisheries activity in the Thau marine lagoon (Mediterranean coast of France) has an old tradition and involves different types of gears (set nets, traps and lines) that are used seasonally with varying frequencies in different areas. A survey of fishing activity, main fishing methods and main commercial species composition in the lagoon was carried out to assess the current fishing effort and seasonal yield. Many important changes in fishing effort and in the most important target species occurred during the last 10 years. A gradual decline in eel, Anguilla anguilla (L.), catches followed by an increase of other commercially-exploited species, particularly the gilthead sea-bream, Sparus aurata L., was observed.