Preliminary Studies on the Visible Migrations of Adult Salmon

1962 ◽  
Vol 19 (1) ◽  
pp. 137-148 ◽  
Author(s):  
D. V. Ellis

Techniques have been developed for observing and recording the behaviour of migrating adult salmon. Daytime movement through slow water (less than 5 ft/sec (1.5 m/sec)) is by steady swimming in schools. Such steady swimming is interrupted with resting periods at velocities between 3 and 5 ft/sec (1.0–1.5 m/sec) but can be sustained over long periods at velocities less than 3 ft/sec (1 m/sec). Movement through slow water in the Somass River system normally occurs along the line of the deepest channel, wherever this is well defined. Movement through rapids (velocities more than 5 ft/sec or 1.5 m/sec) is by darting interspersed with holding, salmon moving individually rather than in schools. Migration through pools, and through other obstructions such as fishways shows diurnal rhythms, modifications of which are associated with numbers of salmon moving, the time within the migratory season, and the species concerned. Nocturnal migration occurs.Entry of salmon into rivers during the migratory season occurs at intervals, the initiating stimulus for which is frequently related to the passage of atmospheric warm fronts over the river estuary.Techniques for field behaviour studies of salmon migration have a potential for management in that it is possible to undertake such studies in areas scheduled for industrial development and to utilize the revealed spatial and temporal migration patterns in the design of fish diversion facilities.

Author(s):  
Chen-Fa Wu ◽  
Chen Yang Lee ◽  
Chen-Chuan Huang ◽  
Hao-Yun Chuang ◽  
Chih-Cheng Weng ◽  
...  

AbstractThe Gonglaoping community is located in Central Western Taiwan, with approximately 700 residents. The hilly landscape contains farmlands and sloping areas with abundant natural resources. Locals rely on the Han River system and seasonal rainfall for water supply for domestic use and irrigation. Uneven rainfall patterns and high demand for water has led to the overuse of groundwater and conflicts among the people. The surrounding natural forests provide important ecosystem services, including wildlife habitats and water conservation, among others; however, overlap with human activities has brought threats to biodiversity conservation. Considering these challenges, locals were determined to transform their community towards sustainability. The Gonglaoping Industrial Development Association (GIDA) and the Soil and Water Conservation Bureau (SWCB) joined hands to initiate the promotion of the Satoyama Initiative, playing catalytic roles in several implementations, such as establishing water management strategies based on mutual trust, rebuilding the masonry landscape, and economic development, forming partnerships with other stakeholders. This multi-stakeholder and co-management platform allowed the community to achieve transformative change, particularly in resolving conflicts of water use, restoring the SEPL, enhancing biodiversity conservation, and developing a self-sustaining economy.Achieving sustainability in a SEPL requires the application of a holistic approach and a multi-sector collaborating (community-government-university) platform. This case demonstrates a practical, effective framework for government authorities, policymakers and other stakeholders in terms of maintaining the integrity of ecosystems. With the final outcome of promoting a vision of co-prosperity, it is a solid example showing a win-win strategy for both the human population and the farmland ecosystem in a hilly landscape.


Author(s):  
Одон Борисович Дашинамжилов ◽  
Виктория Васильевна Лыгденова

В статье рассматриваются миграции бурятского народа в районах преимущественного расселения в 1959–1989 гг. Анализируются источники и методы исследования этнических миграций. Изучена территориальная специфика пространственных перемещений бурятского населения на фоне миграционных тенденций в России в целом и в восточных районах, в частности. Вычислен его механический прирост/убыль в Иркутской и Читинской областях, Бурятской АССР, определены исторические условия, факторы и географические направления миграций, роль сельско-городских перемещений. Выявлено, что буряты Иркутской области обладали самой высокой мобильностью, благодаря тесным контактам с русским населением, интенсивному аграрному и промышленному развитию региона, из-за чего механический отток из области достиг больших размеров. Если вначале была велика доля так называемых «внутренних миграций», в районах основного расселения, то постепенно роль экономических перемещений усилилась, а роль Бурятской АССР как центра притяжения ослабла. У бурят БАССР на протяжении всего рассматриваемого периода было положительное сальдо миграции за счет притока из Предбайкалья и Читинской области. Миграционная подвижность этноса здесь была значительно ниже, чем в Иркутской области, а масштабы сельско-городских миграций были невелики из-за сравнительно невысоких темпов экономического развития и менее тесных контактов с русским населением. Вместе с тем, приток бурятского населения в республику в изучаемый период последовательно снижался. В Читинской области демографический переход у бурятского населения шел медленнее, чем в других регионах преимущественного расселения. В этой связи миграционная мобильность этноса была очень низкой. Регион исторически отличался самыми невысокими темпами роста промышленного производства, меньшей была интенсивность аграрных переселений. В результате буряты области дольше сохраняли традиционные виды хозяйствования, доля городских жителей была небольшой, распространенность русского языка была невысокой. Мобильность бурят усилилась в 1970-е гг., в основном миграции были направлены в БАССР. Роль республики как региона вселения упала лишь в 1980-е гг. The paper studies migration patterns of the Buryat people in the areas with dense Buryat population in 1959–1989. The sources and methods of studying ethnic migrations are analyzed. The territorial specifics of movements of the Buryat population in the context of migration trends in Russia in general and in the Eastern regions in particular are examined. Net migration rate in the Irkutsk and Chita regions and the Buryat ASSR was calculated. Historical conditions, factors and geographical directions of migration, and the role of rural-urban movements were identified. It was revealed that the Buryats of the Irkutsk region had the highest mobility, due to close contacts with the Russian population, intensive agricultural and industrial development of the region, which is why the migration outflow from the region dramatically increased. At first, most migrations were within the studied areas, but then the role of economic movements gradually increased, and the role of the Buryat ASSR as a center of attraction weakened. During the entire period under review, the Buryats of the BASSR had a positive net migration rate due to inflows from the Baikal region and the Chita region. The migration mobility of this ethnic group was significantly lower than in the Irkutsk region, and the rural-urban migration rate was low due to relatively slow economic development and less contacts with the Russian population. At the same time, the influx of Buryat population to the Republic in the studied period consistently decreased. In the Chita region, the demographic transition of the Buryat population was slower than in other regions under consideration. The region has historically had the lowest industrial production growth rates, and the agricultural migrations were less intensive. As a result, the Buryats of the Chita region had long maintained traditional economies, the share of urban residents was low, and Russian language use was not widespread. The mobility of the Buryats increased in the 1970s, and migrations were mainly directed to the BASSR. The role of the Republic as a destination for migrant flows only declined in the 1980s.


2020 ◽  
Vol 117 (44) ◽  
pp. 27578-27586 ◽  
Author(s):  
Eric J. Koch ◽  
Clotilde Bongrand ◽  
Brittany D. Bennett ◽  
Susannah Lawhorn ◽  
Silvia Moriano-Gutierrez ◽  
...  

The recent recognition that many symbioses exhibit daily rhythms has encouraged research into the partner dialogue that drives these biological oscillations. Here we characterized the pivotal role of the versatile cytokine macrophage migration inhibitory factor (MIF) in regulating a metabolic rhythm in the model light-organ symbiosis betweenEuprymna scolopesandVibrio fischeri. As the juvenile host matures, it develops complex daily rhythms characterized by profound changes in the association, from gene expression to behavior. One such rhythm is a diurnal shift in symbiont metabolism triggered by the periodic provision of a specific nutrient by the mature host: each night the symbionts catabolize chitin released from hemocytes (phagocytic immune cells) that traffic into the light-organ crypts, where the population ofV. fischericells resides. Nocturnal migration of these macrophage-like cells, together with identification of anE. scolopesMIF (EsMIF) in the light-organ transcriptome, led us to ask whether EsMIF might be the gatekeeper controlling the periodic movement of the hemocytes. Western blots, ELISAs, and confocal immunocytochemistry showed EsMIF was at highest abundance in the light organ. Its concentration there was lowest at night, when hemocytes entered the crypts. EsMIF inhibited migration of isolated hemocytes, whereas exported bacterial products, including peptidoglycan derivatives and secreted chitin catabolites, induced migration. These results provide evidence that the nocturnal decrease in EsMIF concentration permits the hemocytes to be drawn into the crypts, delivering chitin. This nutritional function for a cytokine offers the basis for the diurnal rhythms underlying a dynamic symbiotic conversation.


2017 ◽  
Vol 68 (8) ◽  
pp. 1544 ◽  
Author(s):  
D. J. Harding ◽  
R. G. Dwyer ◽  
T. M. Mullins ◽  
M. J. Kennard ◽  
R. D. Pillans ◽  
...  

Catadromous fish species require adequate flows to migrate between fresh and saltwater habitats to reproduce. However, artificial barriers and flow alteration affect fish populations by reducing habitat connectivity and disrupting movement cues. In regulated rivers, it is critical that migratory flow requirements are quantified to optimise water allocation for multiple users. In the present study, we assessed the migratory timing, flow and estuarine aggregation requirements for Australian bass (Percalates novemaculeata). Over 2 years, 66 bass were tracked using an acoustic receiver array in the Logan River (Qld, Australia). Bass performed large-scale downstream movements in response to elevated winter flows (40 and 108m3 s–1), which facilitated migration to the lower estuary, where salinity conditions were appropriate for spawning. Bass migrations occurred only when gonads were mature, despite large flows providing opportunities for movement outside this period. Experimental flow releases from an impoundment (2.1m3 s–1) during winter did not elicit a migratory response. Connectivity between upstream and estuarine habitats was reduced by the presence of instream weirs, with downstream movement across weirs occurring only when sufficient flow magnitude was achieved (>76.1m3 s–1). These findings are relevant for water resource managers formulating environmental flow rules for catadromous fish species in systems with multiple instream artificial barriers.


1975 ◽  
Vol 23 (4) ◽  
pp. 569 ◽  
Author(s):  
RA Farrow

High levels of night-flight activity of the Australian plague locust, Chortoicetes terminifera Walker, occurred on at least five separate occasions during the 1973-74 plague in south-east Australia and resulted in episodic, large-scale invasions at night of parts of southern New South Wales, Victoria and South Australia from more northerly breeding areas. The plague did not, however, reach the severe and damaging levels expected in the areas invaded, since on at least three out of five occasions nocturnal migration continued offshore and resulted in extensive mortality. The relationship between migration patterns and synoptic circulation is shown for each of the five situations, with special reference to the use and limitations of wind trajectories for estimating high-altitude displacement of locusts at night.


1983 ◽  
Vol 34 (6) ◽  
pp. 857 ◽  
Author(s):  
LF Reynolds

Results of a fish tagging study carried out in the Murray River, South Australia from 1974 to 1978, are presented. Of 14 333 fish tagged, 1276 were recaptured and the records of these recaptures yield evidence on the movements of several species of both commercial and recreational interest. Some golden perch (Macquaria ambigua) migrated extensively upstream, many moving more than 1000 km. The migration followed, and appeared to be triggered by, a rise in water level at the onset of major flooding. The upstream migrations, made only by mature fish, appear to be a reproduction strategy to ensure that the eggs, which are buoyant, are distributed downstream. In contrast, common carp (Cyprinus carpio), which lay adhesive, demersal eggs, did not migrate but made only random, short- distance movements. Although data on other species were fewer due to their smaller populations, it appears that Murray cod (Maccullochella peeli) and catfish (Tandanus tandanus), both of which have demersal eggs, show similar movement patterns to carp whereas silver perch (Bidyanus bidyanus), which lays buoyant eggs, is similar to golden perch. The implications of these results, with regard to the establishment and maintenance of populations of each of the species, are discussed.


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