Eurasian perch Perca fluviatilis growth and fish community structure,inside and outside a marine‐protected area in the Baltic Sea

Growth of Eurasian perch Perca fluviatilis L. and fish community structure between sites within a marine‐protected area (MPA) and unprotected sites in the Baltic Sea were examined. Von Bertalanffy, logistic and Gompertz growth models were fitted to P. fluviatilis length at age data, and the logistic model was the most parsimonious for growth between locations. A larger mean maximum size (L_∞) and a smaller instantaneous growth rate (g) were found within the MPA. All three models also predicted that after age seven, fish inside the MPA would be larger. Community structure differed with more P. fluviatilis collected outside of the MPA, and more roach Rutilus rutilus (L.) and bleak Alburnus alburnus (L.) collected inside the MPA. These growth differences may be indicative of recreational fishing effects on P. fluviatilis outside of the MPA, a result of complex interspecific and intraspecific species interactions, or other undetected environmental variation between locations.     

Salty stories,fresh spaces: Lessons for aquatic protected areas from marine and freshwater experiences

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Recreational sea fishing in Europe in a global context—Participation rates,fishing effort,expenditure, and implications for monitoring and assessment

Marine recreational fishing (MRF) is a high‐participation activity with large economic value and social benefits globally, and it impacts on some fish stocks. Although reporting MRF catches is a European Union legislative requirement, estimates are only available for some countries. Here, data on numbers of fishers, participation rates, days fished, expenditures, and catches of two widely targeted species were synthesized to provide European estimates of MRF and placed in the global context. Uncertainty assessment was not possible due to incomplete knowledge of error distributions; instead, a semi‐quantitative bias assessment was made. There were an estimated 8.7 million European recreational sea fishers corresponding to a participation rate of 1.6%. An estimated 77.6 million days were fished, and expenditure was €5.9 billion annually. There were higher participation, numbers of fishers, days fished and expenditure in the Atlantic than the Mediterranean, but the Mediterranean estimates were generally less robust. Comparisons with other regions showed that European MRF participation rates and expenditure were in the mid‐range, with higher participation in Oceania and the United States, higher expenditure in the United States, and lower participation and expenditure in South America and Africa. For both northern European sea bass (Dicentrarchus labrax, Moronidae) and western Baltic cod (Gadus morhua, Gadidae) stocks, MRF represented 27% of the total removals. This study highlights the importance of MRF and the need for bespoke, regular and statistically sound data collection to underpin European fisheries management. Solutions are proposed for future MRF data collection in Europe and other regions to support sustainable fisheries management.     

海参捕捞装置导航中低成本陀螺仪的降噪研究与试验

针对MEMS陀螺仪输出信号中含有的随机漂移噪声造成海参捕捞装置惯性导航精度明显下降的问题,采用时间序列分析法和Kalman滤波算法,对MEMS陀螺仪随机漂移噪声的削减问题进行研究。以MEMS惯性测量单元的实测数据和三维电子罗盘测量的姿态角为样本,对本研究的低成本陀螺仪的降噪效果进行测试,试验结果表明:1)经过降噪处理后的陀螺仪随机漂移信号的方差比陀螺仪原始采样信号的方差降低1个数量级,显著改善了陀螺仪随机漂移数据的精密度;2)以高精度三维电子罗盘实测的姿态角作为参考基准,将降噪后的陀螺仪随机漂移数据导入捷联惯导姿态更新算法程序,在300s时间内,解算出的俯仰角、横滚角和航向角的均方根误差RMSE全部小于1°;与降噪前相比,相应的俯仰角、横滚角、航向角的RMSE分别降低了170.5、97.6和42.5倍,明显提高了惯性导航精度。     

Simulating bimodal tall fescue growth with a degree‐day‐based process‐oriented plant model

Plant growth simulation models have a temperature response function driving development, with a base temperature and an optimum temperature defined. Such models function well when plant development rate shows a continuous change throughout the growing season. This approach becomes more complex as it is extended to cool‐season perennial grasses with a dormant period and bimodal growth curves. The objective of this study was to develop such a bimodal growth model for tall fescue (Schedonorus arundinaceus (Schreb.) Dumort) in the Midwest USA based on multiyear measurement trials. Functions for bimodal growth were incorporated into the ALMANAC model and applied to tall fescue using published tall fescue yields for a variety of sites and soils. Fields of cultivars “Kentucky 31” and “BarOptima Plus E34” were divided into paddocks and sampled weekly for dry‐matter accumulation. These biomass estimates were used to derive weekly growth values by differences between sequential weekly samplings. The measured values were compared to a single tall fescue simulation each year on one soil. Using these results, the ALMANAC model was modified and tested against mean reported tall fescue yields for 11 sites, with one to three soils per site. When we introduced midsummer dormancy into ALMANAC, we assumed dormancy began on the longest day of the year and lasted until the photoperiod was 0.68 hr shorter than the longest. ALMANAC simulated previously reported tall fescue yields well across the range of sites. Thus, ALMANAC shows great promise to simulate bimodal growth in this common cool‐season grass.     

塔里木河下游胡杨物候特征观测

以塔里木河下游胡杨(Populus euphratica)为对象,对胡杨的开花期、展叶期、第一次展叶期、第二次展叶期、果熟期、叶黄期及落叶期等主要物候期进行观测。结果表明:胡杨各物候期中,开花期持续时间最短,3月29日至4月19日,果熟期持续时间最长,5月25日开始,10月13日结束。由于春尺蠖(Apocheima cinerarius)的危害,胡杨有"二次展叶"现象,第一次展叶期为4月4日至5月1日,第二次展叶期为5月13日至6月4日。胡杨叶黄期和落叶期相重叠,叶黄期从9月26日开始,10月28日结束,落叶期从10月11日开始,11月12日结束。胡杨长达4个多月的果熟期与河道洪水期吻合,这有利于种子的传播、萌发及幼苗扎根,促进天然胡杨林种群的更新及演替。     

Current status and future needs of economics research of inland fisheries

Inland capture fisheries (ICFs) provide ecosystem services – fish for food, livelihoods and recreation – to people and therefore have an economic value. Economic valuation can inform the sustainable management of ICFs and ensure they are recognised in trade‐off analysis and decision‐making. This study assesses existing ICFs economic research to identify knowledge gaps. Bibliographic databases were searched for suitable peer‐reviewed articles. The selected studies (n = 75) were analysed for coverage, valuation methodologies and value metrics. A majority of existing studies value recreational ICFs in developed countries. Studies have employed a wide range of valuation methodologies and therefore provide a variety of economic values measured at different units and scales. This study highlights the need for a greater quantity of ICFs economic research that covers a representative sample of ecosystems and fishery types globally. Best practice recommendations are made for a standardised framework to ensure ICFs research generates economically credible and comparable values.     

我国沿岸渔场渔业管理困境与对策研究

沿岸渔场是我国重要的传统渔场,但是,由于近几十年来的过度捕捞以及近年来的环境污染和栖息地破坏,沿岸渔业资源已陷入了日益枯竭的境地。本文指出了我国沿岸渔场渔业管理目前所面临的困境,并在此基础上深入分析了困境产生的根源,最后,从渔业资源管理制度的创新、渔业管理手段的完善、支撑体系的完善、渔场的规划、示范区的设立等方面提出了相应的对策建议,以期为我国渔业管理部门提供决策参考。     

The hotter the weather,the greater the infestation of Portulaca oleracea: opportunistic life‐history traits in a serious weed

Portulaca oleracea, an r‐strategist, is one of the world's most troublesome weeds. During hot seasons, P. oleracea frequently becomes monodominant in choy sum (Brassica parachinensis) fields in Guangzhou city, southern China. Here, we studied the seasonal dynamics of P. oleracea's germinable soil seedbank, population density and above‐ground biomass in choy sum fields that had been cultivated continuously for several years. Using P. oleracea seeds collected from these fields, we tested seed dormancy, survival and germination, seedling growth and generation time. Portulaca oleracea occurred at high levels during the hot season, but its occurrence was low, and the germinable soil seedbank was much greater during the cold season. The weed's opportunistic characteristics allowed it to avoid freezing and to proliferate during optimal conditions. Portulaca oleracea's generation time was very flexible, as short as 31 days during the hot season, but longer than 100 days during the colder season. Seed dormancy tended to be shorter when the seeds were stored at a higher temperature. At a temperature of 35°C, both seed germination and seedling growth showed advantages over those of choy sum. Storage for one year at a temperature of ?20°C or burial in a paddy field did not significantly reduce P. oleracea seed germination. Nevertheless, seed storage at a temperature of 15°C and soil coverage of 0.5 cm on top of the seeds significantly constrained seed germination. ‘Stale seedbed’ and/or coverage of the surface with soil are recommended during the hot season. However, rotation of rice and upland crops is not an efficient method for managing Portulaca oleracea infestation.     

近42 a黄河源区生长季植被净初级生产力变化及其对气象因子的敏感性分析

利用1971—2012年黄河源区5个气象站逐日气象数据,应用修定的Thornthwaite Memorial模型计算了区域内各站植被生长季（4—10月）NPP,分析了NPP的时空变化特征,同时,探讨了黄河源区NPP对各气象因子的敏感性及各气象要素对源区NPP变化的贡献程度。结果表明：42 a来黄河源区NPP在生长季平均以125.1 kg·hm^-2·a^-1·10a^-1呈逐年上升趋势,期间存在10 a主周期变化和5 a～6 a的次周期变化;源区NPP多年来在空间变化中存在明显的地域差异,具有由南向北、自东到西NPP依次减小的分布特征;黄河源区NPP对最高气温、日照和降水量的敏感性最强,而对风速、相对湿度和最低气温的敏感性相对较弱;气象因子对源区NPP的总和贡献西北部大于东南部,这与NPP多年相对变化的地域分布特点是相一致的。