Fluorescence of Extracts from Argentine Hake (Merluccius hubbsi) Muscle and Its Correlation with Quality Indices During Chilled Storage

Argentine hake (Merluccius hubbsi) was stored chilled for 8 days. The evolution of fluorescence of the aqueous and organic extracts of muscle during storage at 4°C was studied and correlated with common damage indices; pH, total volatile basic nitrogen, free fatty acids, and the fluorescence intensity of the aqueous phase showed a good correlation with storage time. The excitation-emission matrices of the aqueous extracts were also obtained. A fluorescence landscape that could be attributed to tryptophan decreased with storage time, meanwhile a peak (around 340 and 400 nm for excitation and emission wavelengths, respectively) is developed during chilled storage.     

不同气候模态下西北太平洋柔鱼渔场环境特征分析

柔鱼冬春生群体广泛分布于西北太平洋,其种群分布与大小受气候变化和环境因子调控。本实验根据中国鱿钓组提供的1995—2011年渔业捕捞数据和海洋环境数据包括海表温度(SSTA)、海表面高度(SSHA)和混合层深度(MLDA)的距平值,分析不同气候模态下(PDO暖期和PDO冷期)柔鱼渔场环境的变化。结果显示,PDO暖期时,柔鱼CPUE高;PDO冷期时,CPUE变低。柔鱼渔场SSTA、SSHA和MLDA年间变化显著,各环境变量的时间变化与PDO冷暖相位对应。SSTA和SSHA与PDO指数负相关,滞后时间分别为–9~10月和–20~17月,且均在0月时相关系数最大;而MLDA与PDO指数呈正相关,滞后时间为–6~5月,在–1月相关系数最大。利用经验正交函数分析了SSTA、SSHA和MLDA时空变化的主要模态,前5个模态特征向量分别反映了西北太平洋柔鱼渔场SSTA、SSHA和MLDA分布场78.73%、32.82%和64.57%的信息。研究表明,气候模态变化驱动柔鱼渔场环境的变化,进而对西北太平洋柔鱼资源丰度产生显著影响。     

大西洋海域大眼金枪鱼年龄与生长的初步研究

根据2001年6~10月在大西洋海域金枪鱼延绳钓渔业中采集的89 ind大眼金枪鱼样本,对其叉长、体重进行测定,并以脊椎骨作为年龄鉴定材料。结果表明,叉长组成为85~186 cm,体重组成为11.5~132.5kg,年龄为2~6龄。体重与叉长关系式为W=4.5026×10-5×FL2.8200。利用一般Von Bertalanffy生长方程来拟合,叉长和体重生长方程为:FL=257.90×(1-e-0.1960(t+3.7919))2.5933,Wt=284.28×[(1-e-0.1960(t+3.7919))2.5933]2.8200。叉长和体重的生长拐点分别为1.07龄和5.75龄。     

Quantifying patch distribution at multiple spatial scales: Applications to wildlife-habitat models

Multiscale analyses are widely employed for wildlife-habitat studies. In most cases, however, each scale is considered discrete and little emphasis is placed on incorporating or measuring the responses of wildlife to resources across multiple scales. We modeled the responses of three Arctic wildlife species to vegetative resources distributed at two spatial scales: patches and collections of patches aggregated across a regional area. We defined a patch as a single or homogeneous collection of pixels representing 1 of 10 unique vegetation types. We employed a spatial pattern technique, three-term local quadrat variance, to quantify the distribution of patches at a larger regional scale. We used the distance at which the variance for each of 10 vegetation types peaked to define a moving window for calculating the density of patches. When measures of vegetation patch and density were applied to resource selection functions, the most parsimonious models for wolves and grizzly bears included covariates recorded at both scales. Seasonal resource selection by caribou was best described using a model consisting of only regional scale covariates. Our results suggest that for some species and environments simple patch-scale models may not capture the full range of spatial variation in resources to which wildlife may respond. For mobile animals that range across heterogeneous areas we recommend selection models that integrate resources occurring at a number of spatial scales. Patch density is a simple technique for representing such higher-order spatial patterns.     

北极狐出血性肠炎病原分离鉴定

从排血便为主要临床特征的濒死期育成北极狐肠内容物中分离到 ５ 株革兰氏阳性大杆菌，各株菌的 ３７℃ ８ 小时厌气肉肝汤纯培养上清液 ０２ｍ ｌ小鼠尾静脉注射，１２ 小时内 １００％ 死亡。生理生化鉴定证实分离菌为产气荚膜杆菌（ Ｂ．ａｅｒｏｇｅｎｅｓｃａｐｓｕｌａｔｕｓ）。血清定型结果表明，分离的 ５ 株菌均为 Ａ 型产气荚膜杆菌。以饲喂狐的变质鱼浸出液静脉注射小鼠引起死亡，并从该浸出液中也分离到 Ａ 型魏氏梭菌，证实该病的发生是饲料传播。     

西北太平洋柔鱼渔情速报系统的开发

The neon flying squid, Ommastrephes bartrami, is one of the most important jig fisheries in the northwest Pacific Ocean. In order to understand the movement of O. bartrami fishing-ground better and supply O. bartrami fishing-ground information for Chinese fishing boats in the northwest Pacific ocean, the fishing condition analysis and forecasting system of O. bartrami was developed successfully. The system was based on established comprehensive database, which included the catch data of O. bartrami (total yields, count of total fishing boats, fishing position etc. ) and oceanic environmental information (SST, SST gradient etc. ). Artificial intelligent technology about case-based reasoning was also combined with GIS component technology successfully in the system. The process and function of system establishment are composed of four parts: setting up of case database for central fishing-ground and its environmental factors, knowledge reasoning of fishery information, GIS visualization analyzing as well as trend forecasting of central fishing-ground and information production mapping. At last as an example of the results, an experimental central fishing-ground forecasting of O. bartrami from 9 to 15 in July 2002 in the northwest Pacific Ocean was given in the paper. The results showed that through three class similar searching forecasting central fishing-ground would move west, and indicating that forecasting of the system for O. bartrami central fishing-ground was correct by comparing to real fishing-ground from 16 to 22 in July 2002. Consequently, artificial intelligent expert system technology about case-based reasoning is a useful method for fishing condition and fishing-ground forecasting.     

Effects of photoperiod on sex steroids and gonad maturation in Arctic charr

Four groups of Arctic charr (age 3+), previously exposed to natural photoperiod, were subjected to different photoperiod regimes from February 20: Simulated natural photoperiod (SNP; Tromsø 70°N), continuous light (LD 24:0) followed by short day (LD 6:18) from either May 1 (L_Feb–May) or June 25 (L_Feb–June), or continuous light (LD 24:0) throughout the experiment (L_Continuous). In females, peak levels of estradiol-17β and testosterone were 6 and 10, 6 and 7, and 3 and 5 weeks advanced, in L_Feb–May, L_Feb–June and L_Continuous, respectively, whereas in males plasma levels of 11-ketotestosterone peaked 8 weeks earlier in L_Feb–May and L_Feb–June than in SNP and L_Continuous. Median ovulation time in L_Feb–May and L_Feb–June was advanced by 10 weeks compared to SNP and L_Continuous, and median spermiation time (first observation of running milt in each individual) in L_Feb–May, L_Feb–June and L_Continuous was advanced by 10, 7 and 5 weeks, compared to SNP. A switch from long to short day early in the reproductive cycle (L_Feb–May and L_Feb–June) apparently resulted in stronger synchronization of both ovulation and spermiation. Ovulation in L_Feb–May and L_Feb–June occurred over 3 weeks (L_Feb–May) and 8 weeks (L_Feb–June), as compared to 10 weeks in the SNP group, whereas all males (except one individual) began spermiating over a period of 3 weeks (L_Feb–June), or less (L_Feb–May), as compared to 7 weeks in the SNP group. Lack of a short day stimulus (L_Continuous), on the other hand, resulted in larger variation in the timing of final maturation, with ovulation and spermiation being spread over 15 weeks. Low egg survival in L_Feb–May (17% versus 60% and 97% for L_Continuous and SNP) indicate that a long day signal of 10 weeks early in the reproductive cycle may be too short to ensure good egg and sperm quality. Photoperiod manipulation did not affect the proportion of maturing fish.     

基于海洋遥感的西北印度洋鸢乌贼渔场形成机制的初步分析

2003年9-11月中国鱿钓船对西北印度洋海域鸢乌贼渔场进行生产性探捕调查，发现在16°N、61°E附近海域存在中心渔场，平均日产达5 t以上，但渔场10 d后迅速消失。本文结合本次调查生产数据和卫星遥感资料对这一渔场进行了分析。渔场形成内在动力在于上升流的存在，它使深海缺氧、营养丰富的海水上涌到表层，上升流影响区域SST低，表层藻类 的繁盛，海表面叶绿素a（Chl-a）浓度值高。溶解氧缺乏，驱使鸢乌贼朝溶解氧比较丰富的区域即向SST高值和Chl-a低值的区域聚集，但鸢乌贼也有朝食物丰富区域即Chl-a高和SST低值区域觅食习性。鱼群易集中在SST梯度较大且Chl-a梯度较大的狭长区域。同时，当该海域附近上升流发生后，低压扰动有利于较大的SST梯度及Chl－a梯度的出现和维持，渔场海洋环境复杂，鱼群迅速聚集，形成中心渔场；而当低压扰动消失，风速增大，风向单一，渔场海洋环境单一均匀，鱼群会很快分散，中心渔场消失。     

Arctic charr in Britain and Ireland – 15 species or one?

Abstract –  From both a modern and a historical perspective there is little doubt that the Arctic charr, Salvelinus alpinus , in Britain and Ireland (as well as elsewhere) is a 'difficult' species. Historically 15 separate species have been recognised from populations in Britain and Ireland and there have been recent attempts to reassert these specific names. Here we review the evidence for the status of these 'species'. We conclude that the evidence for these 15 being afforded full species status is poor. However, both historical and contemporary data show that Salvelinus alpinus (Linnaeus 1758) in Britain and Ireland exhibits levels of variability in form that is much greater than in other species. We argue that a comprehensive genotypic and phenotypic survey of charr populations in Britain and Ireland is required to determine the full extent of variability and the status of populations with a view of providing suitable protection.     

Effects of stocking of piscivorous brown trout, Salmo trutta L., on stunted Arctic charr, Salvelinus alpinus (L.)

To study the effects on a stunted freshwater population of Arctic charr, Salvelinus alpinus (L.), two groups of large (26–45 cm) individually tagged brown trout, Salmo trutta L., were released and recaptured with gillnets after 1, 7, 11 and 63 weeks. One group of trout was trained on a fish diet before release, and the other, reared on commercial dry pellets, served as a control. Specific growth rates in both groups were negative 1 week after release and approached zero after 63 weeks. Condition factor and internal fat content decreased during the experiment. Although only 11% of the trout stomachs examined contained fish prey, charr represented 79% of the total stomach weight content. Gillnet samples of charr before and 63 weeks after the release of trout indicated a decreasing population size of charr. Individual growth and mean length of charr increased after release of trout, especially for charr at age 4 years. After the release of trout, 35% of the charr were longer than 20 cm as compared with 6% before the release.