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Juvenile steelhead are known to associate with shiner groups, though they also compete for food. Steelhead form dominance hierarchies within cohorts and aggressively defend feeding territories against all other fish. This study focused on the differential effect of shiner competition on steelhead of different social standing. Survival of subordinate juvenile steelhead was significantly enhanced by the presence of redside shiner under laboratory conditions. A factorial experiment in 80 L tanks examined the relative effects of 0, 3, and 9 shiner at 15° and 20°C on the growth and survival of 3 juvenile steelhead per tank. No temperature effect was detected and there was no significant difference in steelhead growth though statistical power was low (n=5). The largest steelhead did not die in any treatment and no steelhead died in the presence of 9 shiner. In treatments where no shiner were present mortality in the smallest steelhead was 80% (p-value
Three experiments were designed to determine if and how steelhead trout, Oncorhynchus mykiss, may affect chinook salmon, O. tshawytscha, when they are confined together as in a raceway or on a barge. We observed groups of chinook and steelhead together and groups of only chinook in a behavioral experiment to determine if steelhead are aggressive and if their presence changed the behavior of chinook. Two physiological experiments were completed to determine if the loading of steelhead on top of chinook and if the introduction of odor from rainbow trout (steelhead not available) caused a change in plasma cortisol levels in chinook. It was found that chinook showed characteristics of a schooling species, while steelhead exhibited territory holding characteristics. Behavioral changes in chinook were observed when steelhead were present. Chinook grouped with steelhead reduced their movements, darted less, were attacked up to 16 times more often, and were found less frequently in the shade than groups of only chinook. Steelhead were found to establish territories and defend them with chases, charges, and nips. In attempts to establish territories and defend them, steelhead attacked chinook as often as they attacked other steelhead even though chinook showed little aggression toward steelhead. In a physiological experiment, chinook experienced the loading of salmonids into their tank. Chinook had higher levels of plasma cortisol at 2 and 32 hours after the loading of steelhead than chinook that were loaded with chinook or controls (no loading). A second physiological experiment with odor showed that chinook that received rainbow odor and those that received chinook odor had similar levels of plasma cortisol. Cortisol levels (two hours after the odor was introduced) were higher in chinook receiving either of the scented waters than in those that did not receive any odor. In conclusion, all three experiments indicated that the presence of juvenile steelhead trout affect juvenile chinook salmon behavior and physiology.
Modern aquaculture is faced with a number of challenges, including public concern about environmental impacts and the welfare of farmed fish. A fundamental understanding of fish biology is central to finding ways to meet these challenges and is also essential for maintaining the industry's sustainability. Furthermore, the behaviour of fish under culture situations has long been ignored despite heavy commercial losses that can result from fish stressed and hence disease-prone, due to bad husbandry techniques. This important book summarises the current understanding of the behavioural biology of farmed species and illustrates how this can be applied to improve aquaculture practice. Informative and engaging, Aquaculture & Behavior brings the reader up-to-date with major issues pertaining to aquaculture. Everyone from fish farmers to upper level students will find this book a valuable and practical resource. Libraries in universities and research establishments where animal behavior, aquaculture, veterinary and biological sciences are studied and taught should have copies of this work on their shelves.
Discover why animals do what they do, based on their genes, physiologies, cultures, traditions, survival and mating advantages, and evolutionary histories—and find out how studying behavior in the animal world helps us understand human behavior. The three volumes of Animal Behavior: How and Why Animals Do the Things They Do cover the breadth of the field, addressing causation, development, function, and evolution in a wide range of animals, from invertebrates to humans. Inspired by Nobel laureate Nikolaas Tinbergen's work, the first two volumes follow Tinbergen's four classic questions of animal behavior, while the third volume supplies integrated examples of Tinbergen's investigative process applied in specific cases. Written in an engaging, accessible manner ideal for college students as well as general audiences, this evidence-based collection provides a fascinating tour of animal behaviorists' findings, such as how animal communication can be truthful or deceitful, the deadly serious business behind clashes in the "battle of the sexes," and how documentation of animal behavior can lead to a deeper understanding of human behavior. Each chapter provides both historical background and information about current developments in animal behavior knowledge.
A number of steelhead (Oncorhynchus mykiss) populations are at risk throughout Oregon, including five populations that are federally listed as threatened or endangered. However, little is known about behavior and survival of these fish as they transition from freshwater to seawater. We investigated whether estuarine survival varies on a temporal scale within or between years, on a spatial scale between zones within the estuary, and between basins within the same distinct population segment. We implanted acoustic transmitters on 69 wild steelhead smolts in the Nehalem basin and 70 in the Alsea basin and compared run timing, migration rate, and estuarine residence times between basins. We also measured gill ATP-ase levels and parasite loads in each basin to evaluate the relationship between these indices and migration timing, life history strategy or age of smoltification. In general, only 40-50% of the wild steelhead smolts tagged at upstream smolt traps were detected entering the ocean, although survival was highly variable among years. The majority of "mortality" occurred in the lower estuary near the mouth. Wild steelhead smolts spent a median of 0.72 and 0.83 d in the estuary in the Nehalem and Alsea basin, respectively, in 2009. This research provides a baseline by which we can monitor temporal changes in the survival and behavior of juvenile salmon in the estuary. Such information is vital for monitoring the impact of estuarine restoration and reiterates the importance of the lower river and estuary environment for smolt survival.
An understanding of social behaviour is increasingly necessary in farm animal husbandry as more animals are housed in groups rather than in individual stalls or pens. There may be economic or welfare reasons for such housing. This book is the first to specifically address this important subject. The chapters fall into three broad subject areas: concepts in social behaviour; species specific chapters; current issues. Authors include leading experts from Europe, North America, Australia and New Zealand.Animal welfare/behaviour issues are becoming increasingly importantCombines theoretical and practical details about the social behaviour of our most common farm speciesWritten by leading experts from around the world
The Atlantic salmon is one of the most prized and exploited species worldwide, being at the centre of a massive sports fishing industry and increasingly as the major farmed species in many countries worldwide. Atlantic Salmon Ecology is a landmark publication, both scientifically important and visually attractive. Comprehensively covering all major aspects of the relationship of the Atlantic salmon with its environment, chapters include details of migration and dispersal, reproduction, habitat requirements, feeding, growth rates, competition, predation, parasitsm, population dynamics, effects of landscape use, hydro power development, climate change, and exploitation. The book closes with a summary and look at possible future research directions. Backed by the Norwegian Research Council and with editors and contributors widely known and respected, Atlantic Salmon Ecology is an essential purchase for all those working with this species, including fisheries scientists and managers, fish biologists, ecologists, physiologists, environmental biologists and aquatic scientists, fish and wildlife department personnel and regulatory bodies. Libraries in all universities and research establishments where these subjects are studied and taught should have copies of this important publication. Comprehensive and up-to-date coverage of Atlantic Salmon Atlantic Salmon is one of the world's most commercially important species Backed by the Norwegian Research Council Experienced editor and internationally respected contributors
Steelhead and rainbow trout are common names for marine-migratory (anadromous) and freshwater-resident forms of Oncorhynchus mykiss, a partially migratory salmonid fish. Anadromous and resident forms are sympatric and can produce offspring with a life history different from their own (i.e., steelhead parents can produce rainbow trout offspring and vice versa). The expression of these alternative life histories is a plastic response to individual patterns of energy acquisition, assimilation, and allocation during juvenile life stages. Individual performance during early stream life is of particular interest because of potential carry-over effects on subsequent growth and developmental trajectories. In a series of experiments in laboratory streams, I determined the influence of individual variation in energy metabolism on behavior, growth, and life-history expression in O. mykiss. Individual variation in energy metabolism was a strong predictor of feeding territory acquisition by juvenile fish during the transition from dependence on maternal provisioning of egg yolk reserves to independent feeding. Feeding territory acquisition was positively associated with standard metabolic rate (SMR) under conditions of an abundant and predictable food supply. When the density of intraspecific competitors was manipulated, the association between SMR and territory acquisition was strongest at intermediate stocking densities, moderate at the highest stocking densities, and weakest at the lowest stocking densities. However, reducing the spatial predictability of food resources within streams reversed the influence of SMR on competitive outcomes. These experiments determined that variation in ecological conditions during early life stages imposes different selection regimes on juvenile O. mykiss and results in physiological divergence among cohorts. Subsequent rearing experiments determined that behavioral dominance influences rates of anadromy and freshwater maturation, most likely through the association between SMR and territory acquisition. In addition to the effects of behavioral dominance, I observed a significant influence of sex, rearing temperature, and individual growth trajectories on the expression of anadromy and freshwater maturation. Partially migratory populations of O. mykiss maintain an exceptionally diverse portfolio of life-history strategies. Results from this work lend insight into a suite of behavioral and physiological processes influencing individual life histories.