Acoustic evaluation of the vertical distribution of dwarf ayu Plecoglossus altivelis altivelis in Lake Biwa

SUMMARY: The vertical distribution of dwarf ayu Plecoglossus altivelis altivelis in the pelagic waters of Lake Biwa was evaluated from June to September in 1995–97 from eight acoustic surveys using a quantitative echosounder. In each survey, echoes from a depth range of 3 m to the sea bottom were collected at a station every 2.7 s for 24 h together with measurements of vertical profiles of water temperature and chlorophyll-a. The ayu's echoes were identified using an underwater video camera. The ayu were observed near the maximum chlorophyll-a depth and above the thermocline. Their density was highest at depths of 4–11 m with 2–4 individuals/m ³ and was almost zero below 20 m. Echo signs were recorded as having a frequent duration of more than 1 h at night, whereas were of a shorter duration in the day. The fish stay in the epilimnion during the day without any clear vertical migration, but are distributed more uniformly at night. The advantages of remaining in the epilimnion are discussed in terms of food availability and predator avoidance.     

评教三结合 推进名师工程的探索与实践

在我国，高等教育由“精英教育”进入国际公认的“大众化教育”时期的背景下，如何保证教学质量，是摆在高等教育管理工作者面前的重要课题。我们结合学校实际开展“评教三结合”，在加强教学管理，推进名师工程方面进行了探索与实践。     

Sensory evaluation of farmed sharpsnout seabream (Diplodus puntazzo)

The first attempts at applying aquacultural techniques to sharpsnoutseabream (Diplodus puntazzo) have proved very promising.One of the factors to keep in mind when analysing the viability of a speciesforindustrial farming is that of consumer acceptance of the product, a variablethat can be measured by sensory evaluation tests. To that end, 107 participantsfrom a number of work centres were assessed with hedonic sensory tests usingsharpsnout seabream samples. For reference purposes, the tasting also includedgilthead seabream samples. Participants were asked to fill out a questionnairethat included questions concerning their preferences for any one fish. Weanalysed the sensory attributes of both fish species using a hedonic scale, andalso their acceptability (disposition to purchase) to consumers. The resultsproved fairly encouraging with a view to sharpsnout seabream large-scaleproduction. All attributes tested in the sensory profile analysis werepositively rated. About 60% of the surveyed population would consider buyingsharpsnout seabream at a price similar to that of gilthead seabream (10),and 85% found it to be pleasing to the eye. Aside from flavour, its texture,juiciness and fat level are the most important appraisal attributes. Efforts toimprove the organoleptic characteristics of the species should focus mainly onthese attributes.     

Chemical, physical and sensory changes of small abalone meat during cooking

ABSTRACT:   Small abalone meats were heated at 80°C and 98°C for 0–120 min and the differences in chemical, physical and sensory changes of the cooked meats were investigated. The decrease in moisture and weight and the increase in browning and Hunter's b -value were relatively higher for cooking at 98°C than at 80°C. After cooking for 20–120 min, the total amount of adenosine triphosphate and its related compounds on a dry weight basis decreased by 17–27% at 80°C and by 30–39% at 98°C; the total amount of free amino acids on a dry weight basis changed insignificantly at 80°C but decreased by 22–35% after cooking at 98°C. The meats cooked at 80°C were higher in cutting force whereas the levels in the samples cooked at 98°C did not decrease until samples had been cooked for 60 min. The hydroxyproline content showed little change during cooking except for in samples cooked at 98°C for 120 min, in which the content was found to be low. The extended cooking at 80°C improved the acceptability of small abalone meat, whereas only the acceptability score of aroma increased significantly for cooking at 98°C.     

农用地估价方法综述

农用地估价的常用方法有：收益还原法、收益倍数法、成本法、假设开发法、市场比较法、影子价格法、享乐定价法、土壤潜力估价法、标准田法等。这些估价方法对我国农用地的可操作性、适用范围．学术界有不同的看法,文章对这些观点进行了综述与分析。     

Active habitat selection by pre-settlement reef fishes

Our understanding of habitat selection by reef fish larvae has changed dramatically in the last 10 years. Fish larvae have long been considered passive particles at the mercy of ocean currents, tides and weather events. For reef fishes, ecological evidence has shown that passive dispersal alone often cannot explain larval distributions, suggesting active behaviour by reef fish larvae. While behaviourally modified passive transport may be important, recent work demonstrates that some reef fish larvae have the capability to actively swim to settlement habitat. They can orientate to reefs from distances of at least 1 km and can swim at speeds of 13.5 cm s^?1 for several days. The question then becomes, what are the cues that fish larvae use to orientate to reefs? Ambient reef sound has been shown to be attractive to reef fish larvae, and current research aims to understand better the nature and use of these acoustic cues. Other potential cues include chemoreception/olfaction, wave cues and visual location of reefs. A better understanding of active habitat selection and the underlying sensory and behavioural mechanisms will improve our knowledge of recruitment processes in reef fish ecology, and may have implications for active management of reef fish populations.