Throughout their lives, prey organisms must balance the tradeoff between fitness-related activities and the risk of predation. To successfully mediate such tradeoffs, prey must have an accurate method to gauge current predation risk. For many aquatic organisms, the use of chemosensory information has been shown to be a ubiquitous and useful tool in mediating predation risk. The chemical cues to which aquatic organisms respond include the odour of known predators and the odour of a damaged conspecific or known or closely related heterospecific. In fishes, the response to damage-released cues from conspecifics or closely related heterospecifics has been shown to be innate, while the response to distantly related unknown heterospecific cues are likely learned. In a series of laboratory and field studies I examined the role of learning in the ability of fathead minnows to respond to damage-released cues of brook stickleback as an indication of predation risk. My results indicate that minnows from a population without stickleback do not recognize stickleback cues as dangerous. However, following the introduction of stickleback, minnows learn to recognize stickleback cues as dangerous. Further study indicated a low ratio of stickleback to minnows in a given population will decrease the likelihood of learning when compared with a similar sized population containing a higher ratio of stickleback to minnows. I also demonstrated that an increase in habitat complexity decreases the ability of minnows to learn to recognize stickleback cues. Studies have further demonstrated that in the face of predation (as indicated by chemical cues from minnows and stickleback) minnows will decrease their antipredator response when in the presence of a fish shoal, especially a shoal of conspecifics. Finally, an examination of the effects of a minnows length, body condition and breeding status indicate that morphological parameters can play a significant role in the intensity of response to he.

The study of animal cognition has been largely confined to birds and mammals; a historical bias which has led to the belief that learning plays little or no part in the development of behaviour in fishes and reptiles. Research in recent decades has begun to redress this misconception and it is now recognised that fishes exhibit a rich array of sophisticated behaviour with impressive learning capabilities entirely comparable with those of mammals and other terrestrial animals. In this fascinating book an international team of experts have been brought together to explore all major areas of fish learning, including: foraging skills Predator recognition Social organisation and learning Welfare and pain Fish Cognition and Behavior is an important contribution to all fish biologists and ethologists and contains much information of commercial importance for fisheries managers and aquaculture personnel. Libraries in universities and research establishments will find it an important addition to their shelves.

The editors and contributors to this volume should be justifiably proud of their participation in the tenth triennial meeting of the Chemical Signals in Vertebrates International Symposium. This meeting was held 27 years after the initial gathering of participants in Saratoga Springs, New York from June 6* to 9*, 1976. Subsequent meetings have been held every three years in Syracuse, New York; Sarasota, Florida; Laramie, Wyoming; Oxford, England; Philadelphia, Pennsylvania; Tubingen, Germany; Ithaca, New York; and Krakow, Poland. This tenth aimiversary symposium was held from July 29* through August 1*' in Corvallis, Oregon and was hosted by the Zoology Department and Biology Programs of Oregon State University. This book also represents the tenth in a series of books on chemical communication, chemical ecology, olfactory and vomeronasal research in vertebrate species. The species covered in the chapters herein range from fish to mammals including humans. By taxonomic breakdown the mammals are the most represented in number of species and chapter contributions. However, the hosts of the meeting endeavored to have some representative contributions covering all of the major vertebrate taxa. As in past years, the meeting was well-represented with just over 100 participants from 13 different nations. Plenary talks focused on some of the non-mammalian groups that have tended to be less represented in these symposia. Thus, we had a very nice overview of comparisons and contrasts of invertebrate chemical commimication to vertebrate systems.

However, our knowledge of this "chemical network" is still negligible.

A variety of fishes possess damage-released chemical alarm signals, that play a critical role in the detection and avoidance of potential predation threats. Recently, it has been demonstrated that the ability of fathead minnows (Pimephales promelas) and finescale dace (Phoxinus neogaeus) to detect and respond to conspecific alarm signals is significantly reduced under weakly acidic conditions (pH 6.0). Rainbow trout (Oncorhynchus mykiss) and brook charr (Salvelinus fontinalis) possess an analogous alarm signaling system. It is unknown, however if the trout alarm signaling system is likewise affected by relatively small changes in pH. I conducted laboratory and field trials to examine the potential effects of acute exposure to weakly acidic (pH 6.0) conditions on the detection and response of conspecific alarm signals by juvenile trout. My laboratory results demonstrate that while juvenile rainbow trout exhibit significant increases in antipredator behaviour under normal pH conditions (pH 7.0-7.2), they do not respond to the presence of conspecific chemical alarm signals (i.e. response is not different from controls) under weakly acidic conditions. Similarly, natural population of brook charr failed to detect conspecific alarm cues in a weakly acidic stream (mean pH 6.11) while they responded to these cues in a neutral stream (mean pH of 6.88). These data suggest significant, sub-lethal effects of acid precipitation on the ability of prey fishes to detect and respond to conspecific alarm cues in natural waterways.

Dramatic changes in the environment, including habitat degradation and climate change, have focused attention on how individuals and populations respond to a shifting biotic and abiotic landscape. A critical step toward meeting this goal is a clear understanding of the capacity of individuals to defend themselves against threats. Changes in water q