Horizontal and vertical movements of juvenile bluefin tuna (Thunnus thynnus) in relation to oceanographic conditions of the western North Atlantic, determined with ultrasonic telemetry

We employed ultrasonic transmitters to follow (for up to 48 h) the horizontal and vertical movements of five juvenile (6.8–18.7 kg estimated body mass) bluefin tuna (Thunnus thynnus) in the western North Atlantic (off the eastern shore of Virginia). Our objective was to document the fishes’ behavior and distribution in relation to oceanographic conditions and thus begin to address issues that currently limit population assessments based on aerial surveys. Estimation of the trends in adult and juvenile Atlantic bluefin tuna abundance by aerial surveys, and other fishery-independent measures, is considered a priority. Juvenile bluefin tuna spent the majority of their time over the continental shelf in relatively shallow water (generally less then 40 m deep). Fish used the entire water column in spite of relatively steep vertical thermal gradients (≈24°C at the surface and ≈12°C at 40 m depth), but spent the majority of their time (≈90%) above 15 m and in water warmer then 20°C. Mean swimming speeds ranged from 2.8 to 3.3 knots, and total distance covered from 152 to 289 km (82–156 nmi). Because fish generally remained within relatively con-fined areas, net displacement was only 7.7–52.7 km (4.1–28.4 nmi). Horizontal movements were not correlated with sea surface temperature. We propose that it is unlikely that juvenile bluefin tuna in this area can detect minor horizontal temperature gradients (generally less then 0.5°C/km) because of the steep vertical temperature gradients (up to ≈0.6°C/m) they experience during their regular vertical movements. In contrast, water clarity did appear to influence behavior because the fish remained in the intermediate water mass between the turbid and phytoplankton-rich plume exiting Chesapeake Bay (and similar coastal waters) and the clear oligotrophic water east of the continental shelf.

An examination of spatial and temporal genetic variation in walleye pollock (Theragra chalcogramma) using allozyme, mitochondrial DNA, and microsatellite data

We used allozyme, microsatellite, and mitochondrial DNA (mtDNA) data to test for spatial and interannual genetic diversity in wall-eye pollock (Theragra chalcogramma) from six spawning aggregations representing three geographic regions: Gulf of Alaska, eastern Bering Sea, and eastern Kamchatka. Interpopulation genetic diversity was evident primarily from the mtDNA and two allozyme loci (SOD-2*, MPI*). Permutation tests ˆindicated that FST values for most allozyme and microsatellite loci were not significantly greater than zero. The microsatellite results suggested that high locus polymorphism may not be a reliable indicator of power for detecting population differentiation in walleye pollock. The fact that mtDNA revealed population structure and most nuclear loci did not suggests that the effective size of most walleye pollock populations is large (genetic drift is weak) and migration is a relatively strong homogenizing force. The allozymes and mtDNA provided mostly concordant estimates of patterns of spatial genetic variation. These data showed significant genetic variation between North American and Asian populations. In addition, two spawning aggregations in the Gulf of Alaska, in Prince William Sound, and off Middleton Island, appeared genetically distinct from walleye pollock spawning in the Shelikof Strait and may merit management as a distinct stock. Finally, we found evidence of interannual genetic variation in two of three North American spawning aggregations, similar in magnitude to the spatial variation among North American walleye pol-lock. We suggest that interannual genetic variation in walleye pollock may be indicative of one or more of the following factors: highly variable reproductive success, adult philopatry, source-sink metapopulation structure, and intraannual variation (days) in spawning timing among genetically distinct but spatially identical spawning aggregates.

Production of Thai sharpunti (Puntius gonionotus Bleeker) in polyculture with carps using low-cost feed

The effectiveness of duckweed and rice bran as a low cost supplementary feed was compared through a six months production trial of rajpunti (Barbodes gonionotus) with carps. Six earthen ponds of 360 m² each were used for the trial. Three ponds received duckweed, while the other three received rice bran as supplementary feed. Fish biomass after six months of rearing increased to an average of 2,056 kg/ha in ponds which received duckweed and 2,056 kg/ha in rice bran treated ponds. The net profit with duckweed and rice bran worked out to Tk. 69.752 and Tk. 73.480 kg/ha, respectively. This study revealed that duckweed is a low cost supplementary feed, particularly for farmers with limited income.

一种制备生物柴油的方法

本发明是一种利用水产加工下脚料制备生物柴油的方法。包括下列步骤： (1)将清洗后的鱼加工下脚料蒸煮至100～120℃，然后加入有机溶剂，搅拌、过滤得溶液I；(2)按溶液I体积的20～50％加磷酸水溶液于溶液I中，得溶液II，再加入与溶液II同体积的水；进行酸洗水洗，通过多羟基吸水性树脂柱脱水得溶液III；(3)在溶液III中加入碱性催化剂与无水乙醇进行转酯化反应，得溶液IV；(4)将溶液IV静置，除去下层甘油层后，对生成的混合脂肪酸乙酯层进行水洗，除去残留的催化剂、乙醇和其它水溶性成分得生物柴油。本发明的优点是：充分利用现有的鱼加工下脚料，减少污染，提高企业经济效益，为水产加工废弃物的利用和生物能源的发展开辟了一条新路。

Modeling evaporation effects in conditional moment closure for spray autoignition

Simulations of an n-heptane spray autoigniting under conditions relevant to a diesel engine are performed using two-dimensional, first-order conditional moment closure (CMC) with full treatment of spray terms in the mixture fraction variance and CMC equations. The conditional evaporation term in the CMC equations is closed assuming interphase exchange to occur at the droplet saturation mixture fraction values only. Modeling of the unclosed terms in themixture fraction variance equation is done accordingly. Comparison with experimental data for a range of ambient oxygen concentrations shows that the ignition delay is overpredicted. The trend of increasing ignition delay with decreasing oxygen concentration, however, is correctly captured. Good agreement is found between the computed and measured flame lift-off height for all conditions investigated. Analysis of source terms in the CMC temperature equation reveals that a convective-reactive balance sets in at the flame base, with spatial diffusion terms being important, but not as important as in lifted jet flames in cold air. Inclusion of droplet terms in the governing equations is found to affect the mixture fraction variance field in the region where evaporation is the strongest, and to slightly increase the ignition delay time due to the cooling associated with the evaporation. Both flame propagation and stabilization mechanisms, however, remain unaffected. © 2011 Taylor & Francis.

用6个微卫星座位研究BMY牛和婆罗门牛的遗传多样性和群体遗传结构

对6个牛微卫星座位的遗传变异及多态性分析,以期了解BMY牛和婆罗门牛的群体遗传结构与育成情况.6个微卫星座位的多态信息含量为在0.524～0.752间,BMY牛、婆罗门牛两个群体的平均期望杂合度和观察杂合度值接近,分别为0.737 6和0.739 6,0 641 2和0.653 7,进入横交固定第二世代的BMY牛期望杂合度值较高,这与我们的育种进展相符.红安格斯的期望杂合度较低(0.460 9)接近日本和牛0.471,暗示红安格斯牛的同质性较高.

Polymorphisms in the C-type lectin genes cluster in chromosome 19 and predisposition to severe acute respiratory syndrome coronavirus (SARS-CoV) infection

Background: Polymorphisms of CLEC4M have been associated with predisposition for infection by the severe acute respiratory syndrome coronavirus (SARS-CoV). DC-SIGNR, a C-type lectin encoded by CLEC4M, is a receptor for the virus. A variable number tandem