Alarm Cues Research Articles

Behavioral responses of a highly domesticated, predator naïve rainbow trout to chemical cues of predation

Fisheries management agencies allocate significant proportions of available resources to rear fish for stocking in lakes, rivers, and reservoirs. However, domesticated fish reared in a hatchery environment may fail to exhibit normal antipredator behavior and can have relatively low survival when released into natural habitats. Exposing hatchery fish to natural predator cues can provide information about their capacity to exhibit appropriate behavioral responses and has the potential to enhance antipredator behavior and subsequent survival in the wild. We investigated immediate behavioral responses to an acute exposure to chemical cues of predation in highly domesticated, hatchery-reared rainbow trout Oncorhynchus mykiss. We used a frequently stocked and economically important strain of rainbow trout, the German Rainbow (GR), which is resistant to whirling disease but particularly susceptible to predation. We exposed individual rainbow trout to alarm cues from conspecifics, kairomones from brown trout Salmo trutta predators, and a combination of the two cues. Fish exposed to these cues exhibited changes in behavior expected to reduce predation risk, including a reduction in time spent actively swimming and exploring, and an increase in time spent frozen. Thus, these highly domesticated, hatchery-reared fish retain the innate ability to express appropriate responses to the threat of predation. Future research should investigate whether repeated exposure to predation cues in a hatchery setting could translate to long-term enhancement of antipredator behavior and increased survival rates, as this would provide a rapid, simple and low cost way to increase the efficiency of stocking programs for recreational purposes and, more importantly, native fish restoration and conservation.

Individual vs. social learning of predator information in fish: does group size affect learning efficacy?

Group-living prey have the opportunity to acquire information about predation risk through individual and social experience. Here, we tested the effect of group size on the efficacy of predator recognition learning via injured conspecific cues or social learning, using fathead minnows (Pimephales promelas) as our test species. First, minnows from three group sizes (one, two or four fish) were conditioned to recognize a novel rainbow trout (Oncorhynchus mykiss) as risky through a single pairing of conspecific alarm cues with trout odour. They were then individually tested for the recognition of trout odour alone. No effect of group size was found on the learned response to trout odour, suggesting that group size does not interfere with the individual assessment of risk via alarm cues. During the conditioning, however, singletons displayed a stronger antipredator response compared to fish in groups, suggesting a context-dependent modulation of their antipredator response intensity due to a dilution effect. Fish that had the opportunity to learn to recognize a trout socially from either one or three experienced conspecifics also responded with the same intensity of antipredator response to the trout odour when tested alone. We hypothesize that the dilution of risk due to the increase of group size balanced the increase of tutor-to-observer ratio when observers directly interacted with tutor(s). This study highlights the potentially conflicting information that may be perceived by social individuals during both individual and social predation learning.

Maladaptive behavioural phenotypes in captive-reared darters (Etheostoma caeruleum, Storer 1845)

The foraging and anti-predator behaviour of captive-reared rainbow darters (Etheostoma caeruleum) was compared to their wild-caught counterparts. Wild-caught darters responded with appropriate anti-predator behaviour (reduced foraging activity) when exposed to alarm cues (e.g. stimuli from damaged skin) from both wild-caught and captive-reared darters, indicating that the diet in captivity did not inhibit the production of alarm cues. Captive-reared individuals did not change their level of activity when exposed to alarm cues; however, their significantly lower baseline activity (movement and prey consumption) makes it unclear as to whether they actually failed to recognize risk. Regardless, captive-reared darters showed little motivation to feed when food became available (i.e. they made few movements to obtain food) and appeared impervious to chemical cues indicating risk. Exposing captive-reared individuals to both semi-natural foraging opportunities and predator-recognition training before their release is recommended.

Does the gathering of shellfish affect the behavior of gastropod scavengers on sandy beaches? A field experiment

Carrion on beaches is an unpredictable and ephemeral resource over time, especially in areas affected by a tidal regime whereby the ground is frequently washed by incoming tides. In this ecosystem, economic activity, such as the commercial harvesting of molluscs, leads to the presence of discarded, damaged and dying specimens of bivalves on the sand. Thus, although carrion usually represents a minor food source on sandy beaches, human harvesting activity can lead to a significant contribution, this being majorly important for scavengers. During low tide, intertidal gastropod scavengers remain buried in the substrate and emerge when they detect carrion. However, in some instances these gastropods may also emerge in response to mechanical disturbance regardless of the presence of food. The study reported here aims at investigating the effect of human activity, such as trampling on sandy beaches during shellfish gathering, on the behavior of the gastropod scavenger Cyclope neritea in terms of emersion and food locating. This goal was achieved by carrying out short-term field experiments on a sandy beach on the European Atlantic coast (SW Spain). The results demonstrate that, as with the presence of carrion on the ground, human trampling affects the behavior of C. neritea, favoring its emersion to the sediment surface and its movement on the ground. It is hypothesized that this is a potential trophic facilitation by shellfishers, since the emersion and movement of gastropods at low tide is induced during the period when the amount of food on the ground increases due to shellfish gathering. Nevertheless, this increased activity also implies a higher predation risk for these scavengers while emerging from the sand. In order to avoid predation, gastropods generally use alarm cues, such as the detection of damaged conspecifics, as an anti-predatory strategy. The behavioral response of C. neritea to the presence of damaged conspecifics was also studied. The results of this study highlight the fact that scavengers emerge from the sediment in response to trampling and the presence of carrion on the sediment surface. Further it is shown that although the presence of damaged conspecifics may act as a cue to gastropods, C. neritea does not respond to this stimulus until it first makes contact.

Active in the sac: damselfish embryos use innate recognition of odours to learn predation risk before hatching

Predation-induced mortality rates of aquatic species are much higher in larvae than in adults. Consequently, the ability of an organism to recognize relevant predators as early as possible could increase its chance of survival, especially in areas with high predator diversity. Heart rates of embryonic cinnamon clownfish, Amphiprion melanopus, were monitored to assess their reaction to damage-released conspecific alarm cues. These cues were then combined with a predator odour in a conditioning trial to establish whether the embryos were capable of learning a predatory threat. Results showed that A. melanopus embryos were not only able to detect and react to conspecific chemical alarm cues, but were also capable of using this information to learn about predation risk before they hatched. This recognition could lead to a number of antipredator behavioural adaptations, such as modifications of habitat choice at settlement, and could affect development and behaviour in postembryonic individuals, all of which may increase their chance of survival.

Comparative investigation of ‘survival’ and fatality factors in accidental residential fires

ObjectiveThis study compares the odds ratio (OR) values of factors associated with accidental residential fires where an individual has died versus fires where all occupants have survived (with no serious injury that required extended hospitalisation). MethodsAnalyses were based on 177 single fatalities (from coronial files) and 183 survivors (from interviews) of accidental residential fires. Results/discussionThe top seven risk factors (OR>10) that were significantly more associated with fatal than survived fires were, in descending order, psychotropic and sedative drug intake, discarded cigarettes, living alone, being aged over 70, being asleep, location in the room of fire origin (RFO) at ignition, and alcohol intake. The five risk factors (OR>10) that were more significantly associated with survived fires were, in descending order, cooking fires, electrical fires, kitchen being RFO, stove being an appliance involved in ignition, and fire in a one or two family dwelling. People who survived were more likely to wake up to non-smoke alarm fire cues (e.g. glass breaking, smoke) than a smoke alarm cue. ConclusionsThis comparative study provides new insights into statistically significant differences in risk factors between fatal fires and those fires where all occupants survived. The implications for fire engineering are complex as most fatal residential fires were associated with cognitive and physical impairment.

Size-based differences determine the contextual value of risky information in heterospecific information use

Behavioural responses to damage-released chemical cues in aquatic species are often examined with emphases on the potential survival benefits accrued by conspecific receivers in accordance with the hypothesis of taxonomic cue conservation. Nevertheless, chemical cues are publically available to any capable receivers in aquatic systems, and therefore convey information on ambient risk levels to unrelated prey species and on the availability of foraging opportunities to potential predators. Many documented alarm response patterns by heterospecific receivers closely match those of conspecifics, suggesting that the contextual value of public information on risk conveyed by alarm cues may be at least as important as their conserved value. To further explore this relationship, we compared the antipredator responses of shoals of three large or three small female Trinidadian guppies, Poecilia reticulata , to conspecific cues or cues from larger or smaller Hart's rivulus, Rivulus hartii , donors to quantify the relative values of publicly available information. Shoals of large female guppies demonstrated functionally similar antipredator responses to damage-released cues from conspecifics and larger heterospecifics, and no response to the damage-released cues from smaller heterospecifics or the kairomones of larger heterospecifics. Shoals of small guppies demonstrated significant antipredator responses to the damage-released cues of size-matched rivulus, but not to those of larger rivulus or to the odours of either size class. Collectively, these results indicate that potential prey assign at least equal importance to conspecific and public chemical cues from unrelated members of the same prey guild indicating elevated levels of predation risk in natural systems.

Chemical communication in cichlids: A mini-review

The family Cichlidae is well-known for pair-formation, parental care, territoriality, elaborate courtship and social organization. Do cichlids use chemical communication to mediate any of these behaviours? Early studies suggest that parent cichlids can discriminate between conspecific and heterospecific wrigglers (but not eggs) using olfactory cues. Some species are able to discriminate between their own brood and other conspecific broods based on olfaction. The young recognise conspecific adults (although not necessarily their parents) through the odorants they release. In both scenarios, protection of the young from predation is the likely selective force. Some male cichlids use urinary pheromones during courtship and spawning to attract females and induce ovulation. Females – in their turn – may base their mate-choice in part on assessment of those self-same pheromones. The same pheromonal system may be involved in establishing and maintaining the social hierarchies in lek-breeding cichlids. Individual recognition is also mediated by chemical communication. Finally, there is ample behavioural evidence that cichlids – like ostariophysan fish – release alarm cues that alert conspecifics to predation danger. Although the effects of these cues may be similar (e.g., increased shelter use, tighter schooling), they are different substances which remain to be identified. Cichlids, then, use chemical communication associated with many different behaviours. However, given the diversity of cichlids, little is known about the mechanisms of chemical communication or the chemical identity of the cues involved. The aim of this mini-review is to persuade those working with cichlids to consider the involvement of chemical communication, and those working in chemical communication to consider using cichlids.

Minnows trust conspecifics more than themselves when faced with conflicting information about predation risk

Prey often face uncertainty when learning about predation risk because stimuli indicating risk can vary in reliability. However, the way this uncertainty is expressed at the individual level is often poorly understood. Here, we compared how prey fish ( Pimephales promelas ) responded to information conflicting with their previous experience when this information came from contrasting sources. First, fish had the opportunity to learn that a novel odour was safe from repeated exposure to the odour in the absence of negative consequences, or they received pseudo-exposures. Then, using one of two learning paradigms, we conditioned fish to recognize that the ‘safe’ odour was actually the odour of a predator. Fish were exposed to the odour paired with either (1) cues released from injured conspecifics (alarm cues), allowing for the fish to learn alone, or (2) cues from a knowledgeable (frightened) conspecific responding to the risky odour, allowing fish to acquire the information via social learning. Fish were tested individually following conditioning, and movement, foraging, shelter use and freezing were quantified. Learned antipredator responses were similar between the two mechanisms for individuals with no prior exposure to the odour. However, fish that knew the odour as safe did not acquire a fearful response to the odour following conditioning with alarm cues, whereas interaction with frightened conspecifics appeared to cause fish to ignore their prior learning of safety, suggesting that learning from a live conspecific was more persuasive than individual assessment via alarm cues. This study adds to the body of literature contrasting the reliability of information sources and their consequences on cognition, communication and group dynamics. • We tested minnows' risk assessment via different sources of information. • Naïve fish responded similarly following social and alarm cue learning. • The use of past information depended on the source of new information. • Social learning was persuasive when conflicting with prior experience. • Alarm cue learning, but not social learning, was latent inhibited.

Application of a putative alarm cue hastens the arrival of invasive sea lamprey (Petromyzon marinus) at a trapping location

The sea lamprey Petromyzon marinus is an invasive pest in the Laurentian Great Lakes basin, threatening the persistence of important commercial and recreational fisheries. There is substantial interest in developing effective trapping practices via the application of behavior-modifying semiochemicals (odors). Here we report on the effectiveness of utilizing repellent and attractant odors in a push–pull configuration, commonly employed to tackle invertebrate pests, to improve trapping efficacy at permanent barriers to sea lamprey migration. When a half-stream channel was activated by a naturally derived repellent odor (a putative alarm cue), we found that sea lamprey located a trap entrance significantly faster than when no odor was present as a result of their redistribution within the stream. The presence of a partial sex pheromone, acting as an attractant within the trap, was not found to further decrease the time to when sea lamprey located a trap entrance relative to when the alarm cue alone was applied. Neither the application of alarm cue singly nor alarm cue and partial sex pheromone in combination was found to improve the numbers of sea lamprey captured in the trap versus when no odor was present — likely because nominal capture rate during control trials was unusually high during the study period. Behavioural guidance using these odors has the potential to both improve control of invasive non-native sea lamprey in the Great Lakes as well as improving the efficiency of fish passage devices used in the restoration of threatened lamprey species elsewhere.

The alarm cue obstruction hypothesis: isopods respond to alarm cues, but do not respond to dietary chemical cues from predatory bluegill

Predator avoidance behaviours occur when prey detect a predator but the predator has not yet detected and identified prey. These defences are critical because they prevent predation at the earliest possible stages when prey have the best chance of escape. We tested for predator avoidance behaviours in an aquatic macroinvertebrate (Caecidotea intermedius; order Isopoda) in a series of three experiments. The first experiment attempted to determine if isopods possess alarm cues by exposing them to stimuli from macerated conspecifics. We then exposed isopods to kairomones from non-predatory tadpoles (Rana catesbiana) and predatory fish (Lepomis macrochirus) that had been fed a benign diet. Finally, we exposed isopods to kairomones of predatory fish that had been fed a diet exclusively of isopods. We found that isopods did not respond to any kairomone cues or dietary cues from any potential predator, but did reduce activity in response to alarm cues. These results suggest that isopods exhibit predator avoidance responses toward chemical cues in a limited setting (they do not respond unless the information suggests an attack has occurred in the immediate past) or that bluegill have the ability to modify or mask the alarm cues from their prey.

Time-sensitive neophobic responses to risk

Prey animals that experience a high background level of risk are known to exhibit considerable phenotypic plasticity in their responses to unknown predators. When background risk is high, prey exhibit neophobic responses to unknown odours, i.e. they show a fear response to any new stimulus. Here, we examine whether temporal variation in the pattern of risk to which prey are exposed influences neophobic responses. To establish prey groups with different temporal patterns of risk, embryonic woodfrogs (Lithobates sylvaticus) were exposed to conspecific alarm cues each morning and control cues in the evening, or conspecific alarm cues each evening and control cues in the morning, for their entire embryonic period. After the tadpoles hatched they were tested at both times of day for known risk cues (alarm cues), unknown predator odours or water control. Tadpoles responded to alarm cues at any time of day, but showed neophobic responses to predator odours only if their test time matched their embryonic risk exposure time. These results demonstrate a high level of sophistication of neophobic responses and points to temporal variation in risk as a key driver of antipredator decision making.

Stress and fear responses in the teleost pallium

Evolution has resulted in behavioural responses to threat which show extensive similarities between different animal species. The reaction to predator cues is one example of such prevailing responses, and functional homologies to mammalian limbic regions involved in threat-sensitive behaviour have been found in the teleost telencephalon. The dorsolateral (Dl) and dorsomedial (Dm) regions of the pallium are thought to perform hippocampus and amygdala-like functions respectively. To what degree these regions are involved in the neuroendocrine responses to stress and predator cues however remains largely unknown. In the present study the involvement of Dl and Dm in such responses was investigated by exposing Nile tilapia (Oreochromis niloticus) to a standardized confinement stress and to skin extract from conspecifics. Nile tilapia develops a characteristic anticipatory behaviour to hand feeding, and effects of skin extract on this behaviour and locomotor activity were studied to characterise threat sensitive behaviour. Nile tilapia responded behaviourally to conspecific alarm cues by reducing feeding anticipatory behaviour. This may reflect a general elevation of alertness, and further studies combining skin extract with other challenges are needed to reveal neuroendocrine effects associated with this predator cue. Confinement stress resulted in an elevation of cortisol and serotonin (5-hydroxytryptamine, 5-HT) metabolism in both Dl and Dm. A similar tendency was observed in fish exposed to chemical alarm cues, but this effect did not reach the level of statistical significance. Hence, limbic responses to stress and fear, akin to those seen in extant mammals, are also present in the teleost lineage.

Aggregation Status and Cue Type Modify Tadpole Response to Chemical Cues

Abstract Many anuran larvae exhibit an antipredator response to chemical cues released by potential predators. The genus Bufo is no exception, as many bufonids exhibit an antipredator response (e.g., reduction in activity) to the presence (recent and current) of predators. Using a mesocosm experiment in a field laboratory setting, we tested solo and groups of Bufo (Incilius) nebulifer tadpoles for an antipredator response to chemical cues produced by 1) the presence of anisopteran nymphs (kairomone cue) and 2) the predation of conspecifics by anisopteran nymphs (a combination of diet and alarm cues, which we termed predation cue). We quantified the magnitude of the response by calculating response strength. We analyzed data with a blocked ANOVA followed by a Tukey's honestly significant difference analysis. We found that chemical cue type (kairomone vs. predation) affected response strength, but aggregation status (solo vs. group) did not. Furthermore, solo tadpoles and groups of tadpoles reduced their activity in response to predation cues, whereas only solo tadpoles reduced their activity in response to kairomone cues, a heretofore unobserved phenomenon. Our results suggest that B. nebulifer tadpoles modulate their response to specific types of chemical cues depending on their aggregation status. As reduced activity comes at a cost to resource acquisition and growth, aggregation status may indirectly affect the life history of B. nebulifer. The elucidation of these potential life history effects may aid managers in estimating anuran population viability.

Time to feed: How diet, competition, and experience may influence feeding behaviour and cannibalism in wood frog tadpoles Lithobates sylvaticus

Abstract Wood frog Lithobates sylvaticus tadpoles develop in temporary wetlands where high population densities can force tadpoles into aggregations that intensify competition and can lead to cannibalism. However, chemical alarm cues released from injured conspecifics could also dissuade cannibalism. The purpose of this study was to test mechanisms that may influence cannibalistic behaviour. We tested whether the tendency of tadpoles to consume conspecifics would increase with the presence of competition and/or cues of profitable diets. Tadpoles placed in 1L experimental containers were tested for feeding initiation times of multiple diets, including conspecific tissues and conspecific tissues combined with chemical cues from the alternative diets (brine shrimp and cornmeal). Tadpoles were tested in the presence and absence of a competitor, and at multiple times over the course of the study. Tadpoles exhibited an altered response to diets over time; however the presence of a competitor reduced response times to all diets including conspecific tissues. Similarly, the presence of specific diets also reduced the response time of tadpoles to conspecific tissues. These results suggest competition among feeding tadpoles could result in aggressive behaviour leading to indiscriminate predation and cannibalism.

Food or fear: hunger modifies responses to injured conspecifics in tadpoles

Animals must balance the conflicting needs to forage and avoid predation. The optimal balance of risk and reward should depend on the individual’s state, particularly hunger status. Satiated individuals are hypothesized to react more strongly to risk than hungry individuals, for which the necessity for food overrides perceived danger. We tested this in wood frog (Lithobates sylvaticus) tadpoles by comparing the response of fasted and fed tadpoles to injured conspecifics (alarm cue) and uninjured conspecifics (control). Food restriction significantly affected the activity levels of tadpoles and the impact of injured conspecific cues on activity. Fed tadpoles responded little to these cues, tending to decrease activity. Hungry tadpoles were more active overall and responded to injured conspecific cues by increasing activity. We propose that hungry tadpoles increase their activity in response to an injured conspecific because, in addition to indicating danger, this cue represents a nutrient source for this opportunistically cannibalistic species, and hungry tadpoles should thus adopt risky behavior to acquire this valuable resource. Differences in hunger may therefore explain variation among studies of tadpole responses to injured conspecifics. Future studies in aquatic organisms should consider the role of hunger status when assessing antipredator behavior.

Temporal constraints on predation risk assessment in a changing world

Habitat degradation takes various forms and likely represents the most significant threat to our global biodiversity. Recently, we have seen considerable attention paid to increasing global CO2 emissions which lead to ocean acidification (OA). Other stressors, such as changing levels of ultraviolet radiation (UVR), also impact biodiversity but have received much less attention in the recent past. Here we examine fundamental questions about temporal aspects of risk assessment by coral reef damselfish and provide critical insights into how OA and UVR influence this assessment. Chemical cues released during a predator attack provide a rich source of information that other prey animals use to mediate their risk of predation and are the basis of the majority of trait-mediated indirect interactions in aquatic communities. However, we have surprisingly limited information about temporal aspects of risk assessment because we lack knowledge about how long chemical cues persist after they are released into the environment. Here, we showed that under ambient CO2 conditions (~385μatm), alarm cues of ambon damselfish (Pomacentrus amboinensis) did not degrade within 30min in the absence of ultraviolet radiation (UVR), but were degraded within 15min when the CO2 was increased to ~905μatm. In experiments that used filters to eliminate UVR, we found minimal degradation of alarm cues within 30min, whereas under ambient UVR conditions, alarm cues were completely degraded within 15min. Moreover, in the presence of both UVR and elevated CO2, alarm cues were broken down within 5min. Our results highlight that alarm cues degrade surprisingly quickly under natural conditions and that anthropogenic changes have the potential to dramatically change rates of cue degradation in the wild. This has considerable implications for risk assessment and consequently the importance of trait-mediated indirect interactions in coral-reef communities.

Environmental factors affecting behavioural responses of an invasive bivalve to conspecific alarm cues

Antipredator defences of aquatic animals depend on various environmental parameters. We studied behavioural responses of a Ponto-Caspian invasive bivalve, the zebra mussel, Dreissena polymorpha, to conspecific alarm cues. We hypothesized that mussels would change their locomotion and aggregation in response to alarm signals. We also hypothesized that body size, light, substratum quality (suitable or unsuitable for attachment) and inclination would affect mussel defences. Changes in horizontal movement of mussels exposed to the alarm substance depended on light. In the presence of crushed conspecifics illuminated mussels (all sizes) moved longer distances than control individuals, whereas in darkness their reaction was the opposite. The response of small mussels was the strongest. Furthermore, the alarm substance reduced upward relocations of all size groups on an inclined surface but at the same time stimulated their downward movement. Large and medium mussels (but not small individuals) exposed to alarm signals formed aggregations more often than control individuals. This effect was only exhibited on sand, unsuitable for mussel attachment. Mussels were generally more clumped on sand than on hard substratum, suggesting that they did not prefer conspecific shells as attachment sites when alternative substrata were available. All responses of mussels to alarm cues tended to be stronger in light, which is an indirect indication of danger. Our study shows that the responses of the zebra mussel to conspecific alarm cues are not limited to activity reduction, as previously thought. They are adjusted to particular environmental conditions and may also involve increased locomotion when relocation to a safer site gives a better chance of survival.

Origin and specificity of predatory fish cues detected by Baetis larvae (Ephemeroptera; Insecta)

Some prey respond to predator cues by altering their behaviour, but the response may depend on predator diet and identity. There are few data on how predator feeding status and diet affect the behaviour of aquatic insects and on the specificity of the response of these prey to different predators. We present the results of four bioassays conducted in microcosms to evaluate the relationship between predator fish diet, predator identity and the predator avoidance behaviour of mayfly prey of the genus Baetis to elucidate the origin and specificity of the antipredator response. Results from the first bioassay indicated that the response of Baetis to predatory trout is independent of diet, which enabled us to rule out the following potential origins of the signal: alarm cues emitted by wounded Baetis conspecifics, salivary enzymes released by feeding fish and excretion products that may contain Baetis and conspecific odours. Thus, we focused further experiments on fish cutaneous mucus as the potential origin of cues that cause Baetis to reduce its activity. In two bioassays, we observed that North American Baetis bicaudatus did not distinguish between five freshwater fish species that co-inhabit the same drainage, despite differences in their relative risk of predation (four predatory salmonid species and one omnivorous sucker species). However, in another bioassay, we observed that European Baetis rhodani larvae did not respond to cutaneous mucus of novel predators (carp, seawater turbot or frog), indicating that Baetis do not show a general response to all mucus donor organisms. Our bioassays identified mucus as the potential origin of the cue eliciting antipredator behaviour in Baetis, providing much needed insight into the specificity of fish-associated chemical cues that cause some prey to respond. Experimental approaches similar to the one used in this study may increase our understanding of the role of chemical cues in aquatic ecosystems.

Alarm cues in Lake Sturgeon Acipenser fulvescens Rafinesque, 1817: potential implications for life-skills training

An experiment was designed to investigate Lake Sturgeon (Acipenser fulvescens) responses to alarm cues and the ontogeny of anti-predator behaviour in response to alarm cues in larval and juvenile sturgeon. A method for alarm cue preparation in larval sturgeon using full-body homogenate and juvenile sturgeon using homogenized skin is described. Larval sturgeon in tanks exposed to alarm cues were shown to exhibit a dramatic increase in activity (e.g. an escape response) (t25 = 4.95, P < 0.0001), whereas juvenile sturgeon in tanks exposed to alarm cues exhibit only marginally significant escape responses (t37 = 2.02, P = 0.051). Alarm cues may be employed in essential life-skills training for sturgeon, which may prove to be instrumental for their recovery.