Peak Mating and Breeding Period of the Humpback Whale —(Megaptera novaeangliae) in Okinawa Island, Japan

Although detailed knowledge on breeding ecology of humpback whales is required for developing effective and sustainable whale watching programs in breeding areas, the breeding ecology of this species is still poorly understood. Hence, we examine the migratory timing of humpback whales in Okinawa that is one of their breeding ground, distinguishing the reproductive status (male, female, or female with a calf), group compositions (singleton, pair, or whales more than three) and group types (singer or competitive group) in order to assess the peak period of breeding activities. A total of 1192 days of photo-identification surveys were conducted from 1991 to 2012 and a total of 7366 humpback whales were sighted during the surveys. Among them, 1284 whales were sex-determined (848 males, 147 females and 289 females with a calf), 1138 singletons, 1416 pairs and 710 groups of more than three whales were observed. Females without calves tended to occur from late January to late February, which was the beginning of the breeding season and male-female pairs were observed most frequently during this period. The peak occurrence of competitive group which was considered a mating-related behavior group, formed by females and males, was also observed during this period. These results indicated that humpback whales peak mating period in Okinawa occurred between late January and late February. Females with a calf tended to increase from mid-February toward the end of the breeding season maintaining a high sighting per unit effort (SPUE) value in late March. We, therefore, suggested that the peak time of birthing and newborn care was probably that period in Okinawa. These findings extended our knowledge on the reproductive ecology of humpback whales in Okinawan waters.

Utilizing Occupancy Models and Platforms-of-Opportunity to Assess Area Use of Mother-Calf Humpback Whales

The Hawaiian Islands, and particularly the Maui 4-island region, are a critical breeding and calving habitat for humpback whales (Megaptera novaeangliae) belonging to the Hawaii distinct population segment. Our aims were to test the use of platforms-of-opportunity to determine trends in mother-calf pod use of the region and to present opportunistic platforms as an alternative method of long-term, cross-seasonal monitoring. Data were collected from whale watching vessels over a 4-year period and analyzed using occupancy models to determine the probability of habitat use of pods with calves and pods without calves within the study area. Detection probability was influenced by survey effort and month for all pod types with detection of adult only pods further influenced by year. Pods with a calf showed a preference for shallow (<100 meters) low latitude waters (<20.7°N), while pods without a calf preferred deeper waters (>75 meters). Results presented here align with previous work, both in Hawaii and in other breeding grounds, which show a distinct segregation of mothers with a calf from other age-classes of humpback whales. The need for long-term continuous monitoring of cetacean populations is crucial to ensure species conservation. Data collected aboard platforms-of-opportunity, as presented here, provide important insight on humpback whale spatial and temporal distribution, which are essential for species protection and management.

Transmission of Avian Influenza Virus by Humpback Whale and Its Stranding along the Atlantic Coast with CO₂Emissions

Humpback whales are migratory, spending summers in cooler, high-latitude waters and mating and calving in tropical and subtropical waters in 14 identified district population segments. It may be possible that the coastal areas are infected with low pathogenic avian influenza (LPAI) during the release of infected humpback whale feces. Therefore, humpback whales can be an effective reservoir of the avian influenza virus (AIV) from the Poles to the Continents to spread AIV to coastal animals. Strong ultraviolet (UV) exposure amidst CO2 emission increase and minimal sunspot number might cause mutations of aquatic virus and humpback whale in the Antarctic and the Arctic. LPAI or highly pathogenic avian influenza (HPAI) is expressed in the Continents under appropriate environmental factors. Since penguins are birds while humpback whales are marine mammals, the humpback whales infected by the mutant virus might cause interspecies transmission to a new host with evolutionary changes. The migration pattern is seasonally similar between migratory bird and humpback whale except: 1) different species of bird versus whale, 2) different landing area of land versus coast, 3) similar infection means of bird feces versus humpback whale feces. The contribution of AIV transmission by whales was several times larger than that by migratory birds. Therefore, the routes of humpback whales should be considered to prevent AIV outbreaks in addition to the flyways of migratory birds. Humpback whale stranding (y) along the Atlantic Coast of the USA was correlated with CO2 emissions (x) to have y = 0.3515x + 18.595 (R2 = 0.4069) during 1992-2016 while y = 0.0652x + 4.5847, (R2 = 0.6128) during 2016-2018. AIV outbreak in 2010 (y) along the Atlantic Coast was also correlated with humpback whale stranding (2016-2018) (x) as y = 0.1387x + 6.8184 (R2 = 0.3966). Since AIV outbreak was linearly (R2 = 0.9967) correlated with the minimum sunspot number, it was postulated that the unusual mortality events of humpback whale stranding might be caused by an infected mutant virus in the Arctic. Consequently, the humpback whales were stranded along major CO2 producing Atlantic Coast States toward the winter habitat of the West Indies during the CO2 emissions and the minimal sunspot number with strong UV radiation. The stranded dead whales should be burned as soon as possible to prevent further deadly viral interspecies transmission of AIV by the coastal animals. Since CO2 emissions were increased in 2017 and the sunspot number was minimal at the end of 2018, serious numbers of whales are expected to be stranded at the Gulf of Maine, States of North Carolina, New York, and Virginia from November 2018 till April 2019. To save humpback whales from the unusual mortality event along the Atlantic Coast, the reduction of CO2 emissions is suggested by replacement of fossil fuels combustion plants with nuclear power plants along the Atlantic Coast of the USA.

Aerodynamic performance of a low-Reynolds UAV with leading-edge protuberances inspired by humpback whale flippers

The aerodynamic forces and flowfield on a delta-wing Unmanned Aerial Vehicle(UAV)with specific airfoil are studied here.The leading-edge protuberances inspired from the flippers of the humpback whale is introduced in present work to watch its effect on stall delaying and drag reduction.Two installing factors,which are amplitude and wavelength of the protuberances,are considered to study the interaction of leading-edge variation and de-tached vortex.Three changes in both amplitude and wavelength are investigated herein.Generally,the modified models have larger stall angle of attack than that of the baseline model;the difference exists in the attainable lift coefficient and drag reduction.

Considerable increase in bowhead,blue,humpback and fin whales numbers in the Greenland Sea and Fram Strait between 1979 and 2014

In the frame of our long-term study of cetacean abundance and distribution in polar marine ecosystems begun in 1979, a drastic increase in the bowbead Balaena mysticetus North Atlantic ＂stock＂ was observed from 2005 on, by a factor 30 and more： from 0.0002 per count between 1979 and 2003 （one individual, n=5430 cotmts） to 0.06 per count from 2005 to 2014 （34 individuals, n=6000 counts）; the most significant part of the increase occurred from 2007 on. Other large whale species （Mysticeti） showed a similar pattern, mainly blue Balaenoptera musculus, humpback Megaptera novaeangliae and fin whales Balaenoptera physalus. This large and abrupt increase cannot logically be due to population growth, nor to survival of a hidden ＂relic＂ population, nor to a changing geographical distribution within the European Arctic, taking into account the importance of the coverage during this study. Our interpretation is that individuals passed through the Northwest and/or Northeast Passages from the larger Pacific stock into the almost depleted North Atlantic populations coinciding with a period of very low ice coverage -- at the time the lowest ever recorded. In contrast, no clear evolution was detected neither for sperm whale Physeter macrocephalus nor for Minke whale Balaenoptera acusrostrata.

Approximating home ranges of humpback and fin whales in Drake Passage and Antarctica

Identifying home ranges—those areas traversed by individuals in their normal foraging,mating,and parenting activities—is an important aspect of cetacean study.Understanding these ranges facilitates identification of resource use and conservation.Fin and humpback whales occur in Antarctica during the austral summer,but information regarding their home ranges is limited.Using opportunistically collected whale sighting data from eight consecutive summer seasons spanning 2010–2017,we approximate the home ranges of humpback and fin whales around Drake Passage(DRA),West of Antarctic Peninsula(WAP),South Shetland Islands(SSI),an area northwest of the Weddell Sea(WED),and around the South Orkney Islands(SOI).Approximate home ranges are identified using Kernel Density Estimation(KDE).Most fin whales occurred north and northwest of the SOI,which suggests that waters near these islands support concentrations of this species.Most humpback whales were observed around the SSI,but unlike fin whales,their distributions were highly variable in other areas.KDE suggests spatial segregation in areas where both species exist such as SOI,SSI,and WPA.Partial redundancy analysis(pRDA)suggests that the distributions of these species are more affected by spatial variables(latitude,longitude)than by local scale variables such as sea surface temperature and depth.This study presents a visual approximation of the home ranges of fin and humpback whales,and identifies variation in the effects of space and environmental variables on the distributions of these whales at different spatial scales.

仿驼背鲸改进减摇鳍的升力系数数值计算及分析

由于海洋的环境复杂且气候多变,因此船舶在航行过程中,会因为洋流的影响而导致船舶的航行受到一定影响,进而产生多自由度运动。而横摇运动作为影响最大的一种运动方式,对船舶的安全航行造成极大的隐患。因此伴随着仿生学的发展,仿驼背鲸改进减摇鳍的出现,可以协助船舶在应对横摇的过程中起到降低运动幅度的作用。为了更好地应用仿驼背鲸改进减摇鳍,发挥其在抵抗海洋环境干扰的作用,本文从升力系数数值计算入手,对其展开深入分析,完善其鳍角升力系数变化量,为船舶的安全航行提供更为丰富的理论依据。

小攻角下驼背鲸减摇鳍的理论计算

通过应用仿驼背鲸前缘突起来提高船用翼的水动力特性已是目前非常热门的话题,为验证前缘突起的高度和突起个数与升力的关系,选用哈尔滨工程大学船舶控制工程教育部工程研究中心在船模水池实验室所做的减摇鳍动态水动力性能实验用的标准NACA0015 4号矩形鳍为研究对象,对其前缘进行正弦波变形,建立数学模型,并应用普朗特升力线性理论和切比雪夫数值逼近法,得出了前缘突起个数对升力的影响不大而突起幅值对升力有显著的决定性作用的结论。

座头鲸胸鳍前缘仿生叶片空气动力学特性研究

仿生学是人类借鉴生物进化成果推进技术进步理论创新的一个重要源泉^([1-3])。座头鲸胸鳍独特的凸凹前缘可以改变胸鳍上流体的流动状态,进而展现优秀的力学特性。因此,座头鲸胸鳍仿生在流动控制及叶片增效方面有着极大的研究价值。该文通过图像处理方式获得座头鲸胸鳍外形,建立以NACA 63_4-021翼型为截面的叶片;通过研究叶片空气动力学性能及叶片涡量分布分析凸凹前缘对叶片的影响。由于凸凹前缘产生的脱体涡,仿生叶片升力系数和升阻比优于对比模型。

仿生螺旋桨噪声性能预报分析

为了研究螺旋桨结构形式对其噪声性能的影响,本文基于某原型桨采用不同设计方案得到不同系列的仿生螺旋桨,利用ACTRAN软件对其进行噪声性能预报分析。将大涡模拟数值计算结果与螺旋桨敞水试验数据比对,验证了大涡模拟数值计算结果的可靠性;在已获得流场信息的基础上对螺旋桨噪声进行计算;根据计算结果,对各系列螺旋桨模型噪声特征点频谱、声指向性、声压云图及衰减特性进行了分析。结果表明,合理地布置凹凸结构、锯齿形叶梢能在一定程度上改善螺旋桨噪声性能。

Appropriate Location and Deployment Method for Successful Iron Fertilization

“High nutrient, low chlorophyll (HNLC)” regions were created by locking iron into sedimentary iron sulfides with hydrogen sulfide available from volcanic eruptions in surrounding oceans. Appropriate locations and deployment methods for the iron fertilization were far from volcanoes, earthquakes and boundaries of tectonic plates to reduce the chance of iron-locking by volcanic sulfur compounds. The appropriate locations for the large-scale iron fertilization are proposed as Shag Rocks in South Georgia and the Bransfield Strait in Drake Passage in the Southern Ocean due to their high momentum flux causing efficient iron deployment. The iron (Fe) replete compounds, consisting of natural clay, volcanic ash, agar, N2-fixing mucilaginous cyanobacteria, carbon black, biodegradable plastic foamed polylactic acid, fine wood chip, and iron-reducing marine bacterium, are deployed in the ocean to stay within a surface depth of 100 m for phytoplankton digestion. The deployment method of Fe-replete composite with a duration of at least several years for the successful iron fertilization, is configured to be on the streamline of the Antarctic Circumpolar Current (ACC). This will result in high momentum flux for its efficient dispersion on the ocean surface where diatom, copepods, krill and humpback whale stay together (~100 m). Humpback whales are proposed as a biomarker for the successful iron fertilization in large-scale since humpback whales feed on krill, which in turn feed on cockpods and diatoms. The successful large-scale iron fertilization may be indicated by the return of the humpback whales if they could not be found for a long period before the iron fertilization. On-line monitoring for the successful iron fertilization focuses on the simultaneous changes of the following two groups;the increase concentration group (chlorophyll, O2, Dissolved Oxygen (DO), Di Methyl Sulfide (DMS)) and the decrease concentration group (nitrate, phosphate, silicate, CO2, Dissolved CO2 (DCO2)). The monitoring of chlorophyll-a, nitrate phosphate, and silicate concentrations after deploying the Fe-replete complex is carried out throughout the day and night for the accurate measurement of algal blooms.

大攻角下仿驼背鲸鳍叶片气动性能分析

为研究大攻角下前缘突节结构对风力机叶片气动性能的影响,基于FLUENT数值模拟,采用RNG k-ε湍流模型分别对标准叶片和仿驼背鲸鳍叶片进行气动特性分析。结果表明,较小的攻角下仿生叶片的气动性能并不如标准叶片。当攻角α≥20°之后,标准叶片出现明显的失速特性,此时带有前缘突节的仿生叶片升力系数也有所降低,但下降趋势比较平缓,大攻角下仿生叶片的升力系数始终高于标准叶片,具有良好的气动性能。风力机叶片特定截面处的速度云图以及叶片表面压强和流线的分布情况表明,叶片前缘特殊的突节结构相当于一个漩涡制造器,正弦前缘波峰处优良的气动性能是仿生叶片在大攻角下依然具有较高的升力系数的主要原因。前缘突节的幅值和个数是影响仿生叶片气动性差异的主要因素。

仿驼背鲸鳍机翼流动特性分析

为研究前缘突节对机翼流动特性的影响,基于NACA0018标准翼型,对具有光滑前缘的标准机翼和具有不同前缘突节的仿生机翼分别进行了流动特性分析。结果表明,标准机翼在20°攻角之后,升力系数急剧下降,失速特性表现明显。而仿生机翼的升力系数也会在某一特定角度出现不同程度的下降,但下降趋势比较缓和。在大攻角下,仿生机翼的升力系数普遍大于标准机翼,可以有效的改善机翼的失速特性。相比于单位长度内的突节个数,突节的幅值对气动特性的影响更为明显。根据特定攻角下机翼表面流线的分布规律可知,波峰的存在使得其所在区域的流动分离相较于光滑前缘机翼发生了推迟,致使仿生机翼在大攻角下依然具有较大升力系数。

Utilization of Whale-inspired Leading-edge Tubercles for Airfoil Noise Reduction

Numerical studies are conducted to explore the noise reduction effect of leading-edge tubercles inspired by humpback whale flippers.Large eddy simulations are performed to solve the flow field,while the acoustic analogy theory is used for noise prediction.In this paper,a baseline airfoil with a straight leading-edge and three bionic airfoils with tubercled leading-edges are simulated.The tubercles have sinusoidal profiles and the profiles are determined by the tubercle wavelength and amplitude.The tubercles used in this study have a fixed wavelength of 0.1c with three different amplitudes of 0.1c,0.15c and 0.2c,where c is the mean chord of the airfoil.The freestream velocity is set to 40 m/s and the chord based Reynolds number is 400,000.The predicted flow field and acoustic field of the baseline airfoil are compared against the experiments and good agreements are found.A considerable noise reduction level is achieved by the leading-edge tubercles and the tubercle with larger amplitude can obtain better noise reduction.The underlying flow mechanisms responsible for the noise reduction are analyzed in detail.

仿生导管桨水动力性能研究

受座头鲸带有前缘凸起鳍的启发,该文将凹凸结节应用于桨叶导边,试图改善导管桨在小进速系数工况下的水动力和空泡性能。运用自编程序,以19A导管+Ka4-70螺旋桨作为原型桨,将导边进行内凹设计:通过改变特定位置剖面弦长,设计出带有凹凸形导边的仿生导管螺旋桨。运用商业CFD软件开展其水动力性能与流动的模拟与分析,建立仿生导管桨性能分析的CFD数值仿真预报方法。开展了导边凹凸结构的变参数计算研究,选择效率提高最多的仿生桨进行了流场分析。基于CFD计算结果,初步发现:①一定范围内导边凹凸结节的间隔步长越小,结节产生的效果越好,且根部结节效果比叶梢附近的结节效果要好。②凹谷处切面的桨叶推力会有所提高以补偿因桨叶表面积减少造成的推力损失。③单一形式的余弦函数曲线不能最大限度地提高桨叶性能,组合函数曲线节能效果最好。