"Local genetic adaptation and homing behavior in anadromous fish favors the formation of local populations across their geographic range of distribution. Spawning- and natal-site fidelity repeated over generations restricts gene flow and allows genetic differences to accumulate resulting in reproductive isolation. This leads to progressive genetic differentiation and population structuring among different river populations. Alewife, Alosa pseudoharengus, are anadromous fish which are estimated to have high rates of reproductive fidelity and hence might show population structuring among different breeding streams. Alewife are fish of economic importance since they have both commercial and recreational value. Alewife populations have been declining over the past decades and conservation measures to restore the populations have been implemented. Since maintaining genetic integrity of natural populations is one of the main concerns, identification of population structure can assist in designing appropriate restocking programs. In this study, I used microsatellite markers developed for shad to study population structuring in alewife. Samples were collected from two sites in Connecticut and one in Lake Michigan and genetic differentiation among these populations was estimated using five microsatellite loci. My studies indicate that microsatellite loci developed for shad can be used for alewife. Results from this preliminary study indicated subtle but significant genetic differentiation among populations. This suggests that care should be taken when restocking alewife from different sites in order to maintain genetic diversity among these populations."

Daily and seasonal movements of adult alewives, Alosa pseudoharengus, were studied at depths of 5 to 18 m in Indiana waters of Lake Michigan near Michigan City. Collections were made June to October, 1971, with gill nets and a bottom trawl and June to September, 1972, with gill nets.There was no significant difference (P > 0.05) between trawl and gill net catch rates in 1971 regardless of time of day. Significantly more fish were caught during early summer than late summer. Noon gill net catches did not differ significantly between stations. At 10 m, midnight gill net catches were larger than noon catches and bottom gill net catches were greater than surface catches.In 1972, June and July gill net catches were greater than August and September catches. Spawning was essentially completed by August, and inshore populations of spawning adults returned to deeper offshore areas.Midnight catches were greater than noon catches at all depths. During the day, alewives were farther offshore than the 15 m station, but at night they moved inshore. Crowding of alewives inshore at night resulted in significantly larger catches at the 5 m than at the 15 m station.Food habit studies in 1971 and 1972 revealed zooplankton comprised the major portion of the alewife diet. The copepod Cyclops bicuspidatus was the main zooplankter consumed. Bosmina longirostris and Eurycercus lamellatus were major cladoceran food items. Major non-zooplankton food items were Cryptochironomous, Chironomous, and larval alewives.Zooplankton and cladoceran percent volume in stomachs increased to maxima in July of each year followed by a general decline. Copepods were the dominant food in June. Chironomid larvae were a major component of the diet in May, 1972, and August of both years. The largest percent volume of alewife larvae in stomachs occurred in September.A comparison of daily movements and food habits by percent composition of food items in alewives collected July, 1971, revealed the dominant zooplankton species in alewife stomachs were Bosmina longirostris, Chydorus sphaericus, Alona affinis, Eurycercus lamellatus, Polyphemus pediculus, Cyclops,bicuspidatus, and Limnocalanus macrurus. B. longirostris and P. pediculus, which accumulate at the surface at night, were consumed by alewives in greatest quantity at midnight and sunset when the alewife is near the surface. The benthic species C. sphaericus, A. affinis, and E. lamellatus were consumed in greatest quantity at sunrise when the alewife is near the bottom.Ball State UniversityMuncie, IN 47306

Ageing methodologies of Lake Michigan alewife were evaluated as a precursor to growth and condition investigations of alewife stocks. Four commonly used aging tissues were evaluated including: otoliths, scales, vertebrae, and opercles. Otoliths were significantly more precise than other structures in all analyses. The accuracy of age determinations given by otoliths was corroborated through length frequency analysis. Total processing time was highest for scales. Whole otolith methodology was used to age alewives from Indiana, Michigan, and Wisconsin based on precision, accuracy, and time efficiency. A trend of higher median lengths and weights in young fish from the Green Bay, Wisconsin site was identified. Older fish grew faster in the main-lake sample sites near Pentwater, Michigan and Indiana waters. The Indiana population had the highest condition factor (K), while Wisconsin had the lowest, with Michigan in between. An overall temporal decline in condition of alewife was identified when compared with historical studies. This is a consideration that may influence salmonid stocking decisions because the alewife serves as their primary food. / Department of Biology

Over the past two centuries, anadromous alewife populations have drastically declined due to damming, inadequate fish passage, overfishing in the ocean and freshwater, climate change, and reduction in habitat quality. Alewife populations are currently assessed by counting adult fish as they migrate upstream, but little is known about resulting juvenile production within lakes. Lack of knowledge of freshwater life history characteristics of juvenile alewife limits our understanding of overall productivity. For this thesis, I fill existing information gaps by (1) characterizing the timing of adult alewife migrations and subsequent spawning (Chapter 2), and (2) assessing juvenile alewife density, size, growth, and mortality within lakes, and abiotic factors influencing these estimates across lakes (Chapter 3). Twenty lakes across coastal Massachusetts were sampled for juvenile alewife and water quality in summer 2014. Each lake was sampled three times: Round 1 (29 May to 15 June), Round 2 (26 June to 16 July), and Round 3 (27 July to 15 August). Analyses of instream adult counts and otolith-based estimates of spawning date from captured juveniles showed a distinct delay (7-28 d) between the beginning of the adult migration run and spawning, and spawning continued 13-48 days after adults stopped migrating. These findings further corroborate recent discoveries that suggest alewife exhibit asynchronous spawning and has large implications for freshwater foodwebs. Lakes, overall, did not produce the same sized fish and there appears to be substantial variations of length-at-age with some lakes exhibiting large differences. No change in length-at-age occurred in August, thus differences were achieved earlier in the growing season. Additionally, all 20 lakes exhibited variable growth, density, and mortality rates that yielded generally weak relationships with abiotic and biotic factors. Juvenile alewife density was positively related to juvenile density in the previous sampling Round, suggesting that a single sampling date may be sufficient to estimate relative lake density across the landscape. Factors affecting growth were not consistent; overall growth was positively correlated with DOC, while the last 20 days of growth was negatively correlated with secchi depth. While different, these responses are likely the result of the same mechanisms, both intrinsically linked with zooplankton abundance, prey availability, and feeding behavior within lakes. No significant correlate was found for mortality. In the future, the data in this thesis can be incorporated into models to improve stock assessments and support timely adaptive management strategies.

Analysis of trophic and population ecology of an introduced (1968- 1969) alewife forage base and resident sportfishes (age 0 and older) indicated several negative trophic interactions within the community complex of Claytor Lake, Virginia. Alewife piscivority represents a potentially significant adverse impact on sportfish recruitment. Alewife consumed the young of at least four sport species. Larval alewife did not inhabit shallow coves and consequently were not a prey item of age 0 sportfish resident in that habitat. Dietary overlaps (Levins' equation) between adult alewife and young-of-year sportfishes indicated that competitive interactions may occur on a time/site-specific basis. Alewife were demonstrated to be highly size-selective planktivores, preferring zooplankters >1.0 mm length. Electivity determinations indicated the importance of considering size distribution of prey species in food-habit studies. Electivity values were often positive for zooplankters ≥1.0 mm and negative for those <1.0 mm length. Comparisons of the zooplankton community following an alewife die-off (1978) and after alewife recovery (1979) indicated that changes in abundance of predominate species were size-related with smaller forms dominating after alewife recovery. The sizes of Daphnia at onset of maturity were considerably smaller following alewife population recovery. Alewife-induced shifts in zooplankton composition toward small forms represent a potentially significant adverse impact on young-of-year sportfishes which are often size-dependent as well as size-selective planktivores. Electivity determinations of young-of-year sportfishes (<50 mm TL) indicated that only striped and white bass positively selected a zooplankton species (Leptodora kindtii) that was concurrently preferred by alewife. Partitioning of the food complex among cove-inhabiting young sportfishes was in evidence. Predation upon one another, as well as cannibalism appeared to be a more critical trophic interaction than competition with each other or alewife. Indirect trophic interactions between alewife and planktivorous sportfish stages may have affected first year growth rates of smallmouth bass, spotted bass, and white crappie which declined compared to results of a previous growth study made prior to alewife introduction. Following the alewife die-off, age 1 white bass and walleye growth rates significantly increased, perhaps in response to reduced competition with alewife. Utilization of alewife (age 0 and age 1 only) by pelagic sportfishes (walleye, striped bass, white bass) and predation of other prey by littoral black basses suggested partitioning of the forage base. In the spring following the alewife die-off, pelagic sportfishes switched to alternative prey and competition among limnetic and littoral-inhabiting piscivores presumably increased. Although alewife were shown to possess several negative traits for a forage fish, no forage species has proven ideal for southeastern reservoirs. Alewife introduction should be limited to systems too cold for threadfin shad, and that are managed primarily for pelagic predators with non-pelagic young or those that are maintained on a put-grow-take basis. Results of this study underscore the importance of assessing community impacts of an exotic species before wide-spread introduction. / Ph. D.

This study was conducted to evaluate the relative roles of trophic dynamics and nutrient concentrations in the development of cyanobacteria blooms. The motivation for this research was to gain insights into how food webs respond to ecosystem-scale changes, using Lake Champlain as a case study. I sought to link field-based observations with experimentally derived data on mechanisms to better understand the processes that drive cyanobacteria blooms. My research addressed three specific topics: (1) associations among phytoplankton and nutrient concentration trends over time, (2) the impacts of planktivory by invasive fish on the ambient zooplankton community, and (3) the role of herbivore zooplankton grazers in determining the composition of the phytoplankton community. I found little evidence of a strong association between nutrient concentrations and phytoplankton community composition during summer months in shallow bays of Lake Champlain prone to annual cyanobacteria blooms. Fish diet analysis indicated that invasive white perch (Morone americana) and alewife (Alosa pseudoharengus) selectively graze on large zooplankton, which has likely led to substantial declines in zooplankton biomass. I used these results to inform the design of a mesocosm study, which tested the effects of zooplankton grazing on phytoplankton and provided support for the theory that large zooplankton grazing pressure changes the size structure, abundance and composition of phytoplankton. High nutrient concentrations support increased levels of ecosystem productivity, but cascading trophic dynamics are additional forces that are likely contributing to the determination of phytoplankton community composition. Collectively, my research suggests that in shallow bays of Lake Champlain, selective grazing by invasive planktivorous fish is shifting the size structure of the zooplankton grazer community and has likely contributed to conditions that favor dominance by cyanobacteria in summer.

Food habit analyses of the young-of-the-year alewife in lake Michigan show zooplankton was the primary component of the diet in 1972 and 1973. Cyclops bicuspidatus contributed the largest portion of the diet in both years. The dominant cladocerans consumed in each year were Bosmina longirostris, Daphnia retrocurva, Chydorus sphaericus, Polyphemus pediculus, and Diaphanosoma brachyurum. Diaptomus spp. was the only other copepod of importance. Chironomid larvae and pupae provided minor volumes in both years.Monthly food habits revealed a general decline in cladoceran percent volume from August to October at the Michigan City and Dunes transects. Bosmina longircstris was the predominant cladoceran in August of both years at both stations. Chydorus sphaericus was a major food item in September, 1972 at the Michigan City transect, and August and September, 1972 at the Dunes transect. Daphnia retraocurva was a primary prey species in August of each year and in September, 1973 at Michigan City, and in August and September of both years at the Dunes transect.Polyphemus pediculus percent volume was greatest in August and September, 1973 at both stations. At the Michigan City transect, Cyclops bicuspidatus was the dominant food item, and was more important in September than August in both years. In contrast, C. bicuspidatus contributed a major portion of the alewife diet at the Dunes transect in each year, but was more important in August than September. Diaptomus spp. percent volume was greatest at the Michigan City transect in October of both years. Chironomids were major food items only in August, 1972 at the Dunes transect.Young-of-the-year alewife food habits in relation to fish length indicated that smaller YOY alewives selected smaller cladocerans and copepods, whereas larger alewives preferred larger cladocerans, copepods, and chironomids.Ball State UniversityMuncie, IN 47306

No description available.

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.

The relationships between watershed characteristics and stream use by spawning alewife (Alosa pseudoharengus) and blueback herring (Alosa aestivalis) in the Rappahannock River drainage were identified. Trends in fish use of 72 tributaries were determined by consulting eighty-eight people from the Rappahannock River area through a questionnaire. These streams were each given an overall rank based on answers to the questionnaire. The watershed characteristics of these streams were determined from topographic maps, land use data, and digital line graphs. Trends in fish use of streams were associated with stream size, and proportions of forest, agriculture, and wetlands. No negative relationships between urbanization or presence of point-source pollution and fish use of streams were found. Forest was positively associated with stream rank, and agriculture was negatively associated with stream rank. Results indicate that, of the watershed characteristics in the Rappahannock River drainage, forest and agriculture have the strongest associations with stream use by spawning river herring. Three sites in a tributary of the Rappahannock River were studied to characterize the spawning habitat of river herring. The sites were sampled and their habitat variables were measured throughout the 1992 river herring spawning season. Densities of river herring adults, eggs, and yolk-sac larvae were highest at the upstream site. Densities of post-yolk sac larvae did not differ significantly among the sites. The upstream site differed from the downstream sites in size, vegetation, hydrology, photic zone depth, pH, and vegetation. At times, pH levels in the upstream site were within the range of lethality reported for blueback herring larvae. Relationships between habitat variables and occurrence of river herring life stages in the upstream site were identified. Effects of tidal condition, time of day, light intensity, and temperature on peaks in densities of river herring life stages in the upstream site were determined by plotting these variables with life stage densities. Trends in water temperature were positively related to peaks in densities of river herring life stages. Logistic regression was used to determine if temperature, light intensity, dissolved oxygen, velocity, depth, and secchi disc transparency predicted occurrence of river herring life stages in the upstream site. Occurrence of alewife early egg stages was positively related to dissolved oxygen and velocity. Occurrences of blueback herring adults and early eggs were positively related to water temperature. / Master of Science