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<0.01). Aggressive interactions between steelhead allowed pathogens to colonize breaks in the skin of stressed fish resulting in death. In 6800 L recirculating stream channels with natural substrate, 10 steelhead were held either alone or with 20 shiner at 15��C. No steelhead died and their growth was not significantly different between treatments, but, in the absence of shiner fin damage was 16 times greater (p-value<0.01) in the smallest three steelhead. If a shiner group was present the smallest steelhead appeared to shoal with shiner to avoid attack by dominant steelhead. / Graduation date: 1999

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. / Graduation date: 1998

Marine consumers and their prey display plasticity that affects the outcomes of their dynamic interactions as well as community structure and ecosystem function. Aquatic chemical signals induced plasticity in consumers and prey from a broad range of taxonomy (phytoplankton to fishes), sizes (microscopic to macroscopic), and habitats (pelagic to benthic), and this complex plasticity strongly affected consumer-prey interactions. Two fishes,

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental toxicants found in anthropogenic mixtures such as crude oil, air pollution, vehicle exhaust, and in some natural combustion reactions. Single PAHs such as benzo[a]pyrene (BaP) also impact fish behavior when animals are exposed in early life stages and for short periods of time. Aquatic animals such as fish may encounter BaP through road runoff and oil spills, but few studies have examined the impact of aqueous exposure on adult fish, and fewer have examined the resulting fitness-relevant behavioral consequences of BaP and PAH mixtures and their long-term persistence. This dissertation targets this gap in the literature by examining how aqueous exposure to BaP influences anxiety-like behavior, learning, and memory in adult zebrafish, and how parental exposure to the PAH mixture, crude oil, combined with hypoxia affects social and exploratory behavior in unexposed larval zebrafish. We found that learning and memory were not affected by 24 hour exposure to BaP, that anxiety-like behavior was minimally affected, and that locomotor parameters such as distance moved and times spent in darting and immobile states were significantly altered by exposure to BaP. Additionally, we found that parental exposure to crude oil and hypoxia decreased larval velocity. Additionally, we examined how crude oil, BaP, and the detergent COREXIT influence a monolayer of mouse and fish endothelial cells, as an in vitro blood-brain barrier (BBB) model. We found that exposure to BaP in particular caused significant damage to both fish and mammal in vitro BBB models, and damage to the BBB is one potential mechanism by which neural integrity and behavior may be influenced. Understanding how these toxicants influence fish brains and behavior will give insight into how fish populations explore and interact with their environment and with predators, and how these interactions persist even when toxicants are no longer present.

During the migration season in 2013 a study on spawning migrating salmon and the effect of water flow on the behavior was conducted of the salmon at the Forshaga hydropower station in the River Klarälven. The River Klarälven with its nine hydropower plants on the Swedish side, constituting migration obstacles for the migrating salmon. Fortum Generation AB has together with the County Administrative Board restored a salmon trap at the lowermost hydropower station in Forshaga, aiming at making it possible for the salmon to swim into the trap, and thereafter be transported by truck past the power plants and then continue their journey to the spawning grounds on their own. Unfortunately, it is believed that the trap does not work as well as it should. In this study, I focused on salmon position in relation to water flow and if the number of salmon that swam into the fish trap differed between salmon with previous experience of the trap (experienced) and salmon without experience (unexperienced). My results showed that there were significantly more inexperienced salmon that entered the trap than experienced salmon. The salmon, regardless of experience, chose a position where the flow was highest. To increase catches of salmon in the fish trap I suggest that one use more attraction water and keep the trap open more hours. My results should be of interest to managers as the trap efficiency has never been evaluated, and no earlier studies about the effect of salmon experience on trap efficiency exist. / Vandringssäsongen 2013 genomfördes en studie på lekvandrande lax och hur vattenflödet påverkade laxens beteende vid Forshaga kraftstation i Klarälven. Klarälven med dess 9 vattenkraftverk på den svenska sidan utgör vandringshinder för den lekvandrande laxen. Fortum har tillsammans med Länsstyrelsen renoverat en laxfälla i det mest nedströms liggande kraftverket i Forshaga. Syftet med fällan är att laxen ska simma in i fällan till en uppsamlingsbassäng och därefter köras med lastbil förbi kraftverken, för att därefter fortsätta vandringen på egen hand. Fiskfällans effektivitet är ifrågasatt och man vet inte hur effektiv den är. I denna studie fokuserade jag på laxens ståndplats i relation till varifrån det huvudsakliga flödet kom, samt om antalet laxar som simmar in i fiskfällan skiljde sig mellan lax med tidigare erfarenhet av fällan (erfaren) och lax utan erfarenhet av fällan (oerfaren). Mina resultat visade att det var signifikant fler oerfarna laxar än erfarna laxar som simmade in i fällan. Laxen, oavsett erfarenhet, valde ståndplats där flödet var som högst. För att öka fångsterna av lax i fiskfällan skulle mer lockvatten och fler timmar då fällan är öppen kunna bidra med mer fångst. Denna studie borde vara av intresse för inblandade aktörer i laxens förvaltning eftersom fällans effektivitet aldrig utvärderats tidigare, och dessutom har man inte studerat om tidigare erfarenhet av en fälla påverkar laxen.

De har gjorts få studier på akvariesfiskars beteende. För att bemöta intresset för akvariefiskar så behöver vi veta mer om deras beteende i en artificiell miljö. Syftet med den här studien är att jämföra det utforskande beteendet hos vildfångade och odlade diamanttetror som är en vanlig akvariefisk. Hypotesen är att det finns en skillnad i deras beteende där vildfångade är mer djärva än de odlade. Grupper om fem individer av diamanttetra vildfångade och odlade släpptes ner i en ny artificiell miljö. De filmades i 20 minuter från de att de släpptes i. Testet upprepades 10 gånger med nya individer och för varje försök togs tiden det tog för varje individ att lämpa botten av akvariet och sedan mättes storleken på stimmen för varje grupp. Jag hittade en skillnad i hur lång tid fiskarna tog på sig för att lämna botten men det var ingen skillnad i höjd eller längd på stimmen. Detta visar att de vildfångade visade ett djärvare beteende än de odlade genom att lämna botten snabbare. Den här studien gav information om skillnaden i beteende för vildfångade och odlade diamanttetror och informationen kan användas för fortsatta studier kring akvariefisk. / The behaviour of ornamental fish is not well studied. To meet the needs of ornamental fish hobbyists, we need to know more about the behavior of fish in artificial environments. The aim of this study is to compare the explorative behaviour of wild-captured and farmed fish in a common ornamental fish, the diamond tetra. The hypothesis is that there is a difference between the two groups behavior where the wild-captured tetras are bolder. Groups of five individuals of farmed respectively wild-captured diamond tetra were released in a new artificial environment where they were monitored for 20 minutes. The test was repeated 10 times with new individuals, and the time it took for them to leave the bottom of the aquarium was measured as well as the size of the shoal. I found a difference in the time it took for the individuals to leave the bottom, with the wild-captured tetras leaving the bottom earlier than the farmed fish. There were no differences in height or length of the shoal. Thus, the wild diamond tetra were bolder than the farmed tetras. The study gave information about the differences in behavior between wild-captured and farmed diamond tetra and can give information to further studies about ornamental fish.

Conserving and restoring anadromous fish populations is an important research and management priority. For conservation to be effective, researchers must understand the behavior of the fish they seek to restore. Telemetry has allowed researchers to understand the upstream migrations of these fish in freshwater, how migration patterns vary, and if there is a relationship between behavior and environmental variables. In the northeastern United States, alewife (Alosa pseudoharengus), one of two species collectively referred to as river herring, has historically been an important component of coastal rivers. However, populations of these fish have experienced recent declines, and a commonly used method to restore river herring is stocking. In this thesis, I summarize research that seeks to understand anadromous alewife behavior with the goal of providing insights that will help manage and conserve this species and the coastal systems in which they live. My thesis has a primary research chapter (Chapter 1), a second ancillary research chapter (Chapter 2), and four appendices that summarize related information as part of the funding proposal. First, to examine if fish origin (native or stocked) and fish release location (upstream or downstream) affected the pre-spawning movements of fecund alewives, I undertook a reciprocal experiment. In Chapter 1, for fish of both origins and release locations, I examined how long fish were in the river, where they spent their time, and how much and how fast they moved. For this, I gastrically tagged alewives with Lotek Nanotags NTC-6-1 radio tags and monitored movements in the lower 30 km of the Ipswich River (northeastern Massachusetts) using an array of 9 Lotek SRX_400 receivers. Based on these movement trajectories I concluded that in 2007, origin affected the total time fish spend in the river and release location affected where they spend their time. Downstream movements of upstream migrating fish have typically been viewed as a behavioral assay of adverse tag effects. For this reason, alosine telemetry studies rarely release tagged fish upstream of the capture site. However, fisheries managers often release fish upstream near spawning grounds during stocking. In Chapter 2, I re-evaluated whether downstream movements of upstream stocked fish were consistent with an adverse tag effect. By combining physiological experiments with select movement trajectories, I showed that pre-spawning migrations of alewife included an array of up and downstream directed movements with various interpretations. In my research, these downstream movements were unlikely to be related to tagging stress (Chapter 2), as the cortisol, glucose, and chlorides of tagged fish were not different from untagged fish (Appendix A, Physiology). Furthermore, I suggested metrics that should be recorded in telemetry studies to standardize how downstream fish movements are measured. In 2006, native fish were released at a downstream site (river km 6) and stocked fish were released upstream (rkm 25). I compared the behaviors of these same treatments across years. I showed that the behaviors of fish released in different years may differ based on temperature and discharge (Appendix B, Across Year Comparison). To determine the amount and location of potential spawning habitat, I undertook a habitat study that utilized a geographic information system (GIS) to maps the size and distribution of habitat types. I located multiple mainstem pools in the Ipswich River that may serve as suitable spawning grounds for alewife. Tagged fish were primarily located in these habitats (Appendix C, Habitat). To determine if juveniles were produced, I sampled various sites in the river for the presence of juveniles, using active and passive sampling techniques. Juveniles were not captured during these surveys (Appendix D, Juvenile Sampling). Before this research, little was known about the pre-spawning migrations of river herring. While river herring are assumed to be a generalist species, I found their behaviors to be complex. I have identified a number of gaps in the current knowledge of how these fish behave in the field. Restoration efforts must take into account the behavior of the fish, as well as the capacity of a system to accommodate those needs. Within the context of understanding fish behavior, protecting habitat, and providing regulatory restrictions on the fishery, stocking may contribute to broader management and restoration goals.

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