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At least 1,297 records · Page 72Linked to original sources
USGS2012

Time-specific patterns of nest survival for ducks and passerines breeding in North Dakota

In many bird species, survival can vary with the age of the nest, with the date a nest was initiated, or among years within the same nesting area. A literature review showed that patterns of survival vary in relation to nest age and date and are often contradictory. Inconsistencies could be a result of temporal variation in the environment or life-history differences among species. We examined patterns of nest survival in relation to nest age, date, and year for several duck and passerine species nesting at a single location in North Dakota during 1998–2003. We predicted that if environment shaped nest survival patterns, then temporal patterns in survival might be similar among three species of upland nesting ducks, and also among three species of grassland passerines nesting at the same site. We expected that survival patterns would differ between ducks and passerines because of relatively disparate life histories and differences in predators that prey on their nests. Nest survival was rarely constant among years, seasonally, or with age of the nest for species that we studied. As predicted, the pattern of survival was similar among duck species, driven mainly by differences in nest survival associated with nest initiation date. The pattern of survival also was similar among passerine species, but nest survival was more influenced by nest age than by date. Our findings suggest that some but not all variation in temporal patterns of nest survival in grassland birds reported in the literature can be explained on the basis of temporal environmental variation. Because patterns of survival were dissimilar among ducks and passerines, it is likely that mechanisms such as predation or brood parasitism have variable influences on productivity of ducks and passerines nesting in the same area. Our results indicate that biologists and managers should not assume that temporal environmental variations, especially factors that affect nest survival, act similarly on all grassland birds.

North Dakota↗
USGS2011

Nest predation and circulating corticosterone levels within and among species

Variation in the risk of predation to offspring can influence the expression of reproductive strategies both within and among species. Appropriate expression of reproductive strategies in environments that differ in predation risk can have clear advantages for fitness. Although adult-predation risk appears to influence glucocorticosteroid levels, leading to changes in behavioral and life-history strategies, the influence of offspring-predation risk on adult glucocorticosteroid levels remains unclear. We compared total baseline corticosterone concentrations in Gray-headed Juncos (Junco hyemalis dorsalis) nesting on plots with and without experimentally reduced risk of nest predation. Despite differences in risk between treatments, we failed to find differences in total baseline corticosterone concentrations. When we examined corticosterone concentrations across a suite of sympatric species, however, higher risk of nest predation correlated with higher total baseline corticosterone levels. As found previously, total baseline corticosterone was negatively correlated with body condition and positively correlated with date of sampling. However, we also found that corticosterone levels increased seasonally, independent of stage of breeding. Nest predation can alter the expression of birds' reproductive strategies, but our findings suggest that total baseline corticosterone is not the physiological mechanism regulating these responses.

The Condor↗
USGS2015

Geological processes and orchid biogeography with applications to southeast central America

This contribution owes its origins to a paper presentation by Dr. Calloway H. Dodson at the Second International Conference on Neotropical Orchidology held in San José, Costa Rica in May of2003 (Dodson 2003). Dr. Dodson outlined some ofthe reasons to suspect that regional geological fac-tors may play important roles in orchid speciation and biogeography and gave examples from the northwestern South America. He also suggested that evolutionary change in orchid might occur over fairly short time periods, perhaps even as short as decades, centuries or millennia (Dodson 2003, SHK lecture notes). These ideas stimulated the author, a professional earth scientist, to begin thinking about how these exciting ideas could begin to be tested in Costa Rica neighboring and Central American countries, an area that has drawn him to return frequently over the last decade. The present contribution is a proposal for integrating geological observations, such as the chronology of arc volcanic activity in Nicaragua,Costa Rica, and Panama, in hypothesis forming and testing of the geographic distribution of orchids (and possibly other biota). I initially focus on comparisons between orchid inventories on the windward slopes of mountainous regions (elevation > 1000 m)with high rainfall (> 1-2 m) in tropical regions, the so-called tropical cloud forests. These regions represent the tropical pre-montane rain forestto lower montane tropical rain forest life zones of Holdridge(1967) and the montane vegetation zone applied to Costa Rica and Panama by Dressler (1993). An important message of this paper is that such tropical mountainous regions are not necessarily static, but may change in elevation over geologic time due to active tectonic deformation and uplift and that the presence of active volcanism in a mountain range may also introduce additional chemical factors, such as volcanic gases, acid rain, and volcanic soils, and also physical factors, such as interruption of gene flow by explosive eruptions and coverage by their air fall products such as ash (tephra), lava flows, and lahars (volcanic mudflows). Thus over a given geological time interval, forests may be slowly increasing in elevation by tectonic uplift or by the accumulation of volcanic products such as steep-sided strato volcanoes (built from both lavas and tephra), or by down-slope accumulations of lava flows or lahars. Mountains may also lose elevation by erosion or by tectonic subsidence. As we shall see, tropical Central America shows an extraordinarily high level of tectonic and volcanic history that has changed its geography and, by implication, climate, life zones,and likely orchid distribution. My working hypo thesis put forward for testing is that orchid adaptations to these changes may have led to the development of new species and endemism in this region.

Lankesteriana↗
USGS1987

Faces from the past: Frederic Morton Chamberlain (1867-1921), pioneer fishery biologist of the American West

The life of Frederic Morton Chamberlain (1867–1921) was marked by his many contributions to fishery science. As an assistant with the old U.S. Bureau of Fisheries, he pioneered life history studies of salmon in California and Alaska, and assisted in the collection of hundreds of thousands of natural history specimens from the Pacific Ocean as resident naturalist on the U.S.S. Albatross . He was innovative in the use of field photography in fishery work, and the design and construction of capture nets and collecting gear. His detailed reports were important in documenting the conditions of the native ichthyofauna in Alaska, Arizona, and California at the turn of the century and have been heavily relied upon by subsequent investigators. His ability to design and conduct scientifically justifiable studies to solve fishery problems while under many kinds of hardships is a testament to his background and dedication to the field. He represents the prototype of the modern fishery biologist.

Fisheries↗
USGS1949

Fact and fiction in spawntaking: Addenda

I was glad to see "Fact and Fiction in Spawntaking" by Wood and Dunn (1948) in a recent issue of the PROGRESSIVE FISH CULTURIST. Having spent two seasons at the Yellowstone Park station, I also attempted to find ways of increasing the efficiency of fertilization and several years ago conducted a few experiments along these lines. From these experiments I obtained some "facts and fiction" that I believe are particularly germane and will be of interest to anyone who spawns fish. I often dreamed of some Utopian technique for spawning fish--a technique that would insure 100-percent fertilization. My approach to this was an attempt to find a solution that would keep the sperm viable and active for a period of minutes rather than seconds and one that would allow eggs to remain receptive to the sperm for the same period. The work of Ellis and Jones (1939) indicated that a solution of comon salt would prolong the life of fish sperm, although the work of Schlenk and Kahmann (1938) indicated that a more complex solution must be used. I therefore tested on sperm many solutions which waried in composition, strength, pH, and temperature. None of these prolonged viability to the point where 100-percent fertillzation could be expected after a few minutes" exposure at best. There was no difficulty in prolonging the fertilizable life of the egg: a plain salt solution was found quite effective, as mentioned by Rutter (1904).

Progressive Fish-Culturist↗
USGS1952

Diseases and parasites of the sea lamprey, Petromyzon marinus, in the Lake Huron basin

Sea lampreys from the Lake Huron basin carried no external parasites and showed a fairly low degree of infection by internal parasites. The material examined represented three life-history stages of the sea lamprey. Recently transformed downstream migrants (215 specimens) harbored only nematodes belonging to the genus Camallanus. The percentage of infection was 2.3. Active feeders from the lake (29 lampreys) revealed the highest degree of parasitism (31.0 percent) with the following parasites present: Echinorhynchus coregoni Linkins; Triaenophorus crassus Forel; and Camallanus sp. Among the 257 sexually mature upstream migrants (14.8 percent infected) Echinorhynchus coregoni and E. leidyi Van Cleave were the most common. Only occasional nematodes and cestodes were found, which fact indicates a failure of the lamprey to carry these parasites to the end of its natural life. Of the parasites observed, only the nematodes gave evidence of serious damage to the host. The study suggests that the role played by parasites in the natural control of the sea lamprey in its new habitat in the upper Great Lakes is of minor importance.

Transactions of the American Fisheries Society↗
USGS1967

Growth of lake trout in Lake Superior before the maximum abundance of sea lampreys

The growth in length of lake trout (Salvelinus namaycush) from the inshore water of Lake Superior in 1953 increased with age from the 3rd to 9th year, and was nearly constant from the 9th to the 12th year. Growth was greatest in the 1st year (4.0 inches) and least in the 2nd and 3rd years (2.3 inches). Between the 4th and 9th years the increments increased from 2.6 to 3.5 inches. Growth was calculated from a curvilinear body‐scale relation. Intraseasonal growth in length extended from late April until well after October; most growth was in late summer and fall. The younger fish started growth earlier, and some mature fish did not increase in length until after the October spawning. Lake trout reached the minimum legal weight (1.5 pounds) in the 7th year of life and the average size taken in the commercial fishery (about 3 pounds) in the 8th year. The annual increase in weight in the 8th year of life was over 64%. Fish used in this study grew more slowly than those from Lakes Michigan and Huron taken during the period when sea lamprey abundance was increasing, but at about the same rate as lake trout of Lake Michigan before the sea lamprey appeared.

Lake Superior↗
USGS1977

Age and growth of the walleye in Lake Erie, 1963-1968

Age and length distributions are given for 6,764 walleyes, Stizostedion v. vitreum (Mitchill), sampled during 1963-1968 from commercial landings of walleyes representing discrete populations in the eastern and western basins of Lake Erie. In the eastern basin, where all catches were made with gill nets, age-groups III and IV predominated in samples from large-mesh nets and age-group I in samples from small-mesh nets. In the western basin, where nearly all walleyes were taken in trap nets, age-groups I and II predominated in 1963-1965, and II and III in 1966-1968 (after the legal commercial size limit was raised from 330 to 394 mm). Study of 5,082 walleyes from the two basins showed that at any given age during the first 3 years of life, females were longer than males and, on the average, fish from the western basin were longer than those from the eastern basin. The greatest difference in growth of fish of the same sex for the two basins was apparent at the end of the first year of life, when fish from the eastern basin were only about half as heavy as those from the western basin. After the second year, relative growth in weight of fish in the eastern basin improved: the weight of females exceeded that of females in the western basin by the end of the fourth growing season and the weights of males in the two basins were about equal by the end of the sixth growing season.

Transactions of the American Fisheries Society↗
USGS1981

Culture, feeding, and growth of alewives hatched in the laboratory

Alewives (Alosa pseudoharengus) were reared from the egg to the early juvenile life stage. The major obstacle to rearing alewives from the egg — providing an acceptable food that facilitates first feeding — was overcome by presenting a mixture of wild Zooplankton to the larvae twice daily, beginning on the day of hatching. Initial feeding by larvae held at 20°C was observed 2 days after hatching, when the yolk was nearly absorbed. Comparison of stomach contents and the wild Zooplankton composition suggested that the diet of larvae during the first 15 days of life shifted with changes in the availability of food but remained within a fairly narrow range of food sizes. Larvae hatched at a mean total length of 3.8 mm and grew at an average rate of 0.62 mm per day, to a mean of 35.5 mm after 50 days. At 50 days most fish had transformed into juveniles. The daily instantaneous mortality coefficient was 0.018. About half of the mortality occurred during the first 13 days after hatching.

Progressive Fish-Culturist↗
USGS1993

Interaction between native and nonnative fish of the upper Muddy River, Nevada

I investigated interactions between native and nonnative fishes in the upper Muddy River system to add insight into (1) the mechanism causing the decline of the Moapa dace Moapa coriacea after the introduction of the shortfin molly Poecilia mexicana , (2) the reason Moapa White River springfish Crenichthys bailevi moapae were less affected by the introduction, and (3) the reason interactions between natives is relatively benign. I investigated the hypothesis that the shortfin molly caused the decline of the Moapa dace through competition or predation on larvae, pressures not experienced by the Moapa White River springfish. Relative interspecific competition was analyzed by contrasting the ranges of spatial and dietary overlap among larval, juvenile, and adult life stages. There appeared to be moderate to low spatial overlap between the various life stages of native and nonnative fishes. Overlap in diet was highest between adult Moapa White River springfish and shortfin mollies. Laboratory experiments suggested that shortfin mollies prey vigorously upon fish larvae. In terms of spatial habitat use, Moapa White River springfish larvae were less available to adult shortfin mollies for consumption than were Moapa dace larvae. When predation on larvae is the mechanism by which nonnative fish reduce native forms, aggressiveness of the predator and the degree to which the predator overlaps in habitat with the prey may influence the degree to which a native fish population is affected.

Transactions of the American Fisheries Society↗
USGS1997

Food habits of Atlantic sturgeon off the central New Jersey coast

Limited information exists on the marine diet of the Atlantic sturgeon Acipenser oxyrinchus oxyrinchus . We examined the food habits of 275 Atlantic sturgeon (total length, 106–203 cm) caught in the commercial fishery off the coast of New Jersey. Stomachs were provided by fishermen. Significantly more stomachs were empty in the spring than in the fall. Sand and organic debris were a major component in the stomachs (26.3–75.4% by weight). Polycheates were the primary prey group consumed, although the isopod Politolana concharum was the most important individual prey eaten. Mollusks and fish contributed little to the diet. Some prey taxa (i.e., polychaetes, isopods, amphipods) exhibited seasonal variation in importance in the diet of Atlantic sturgeon. Identification of the offshore diet of Atlantic sturgeon is an important step in developing a better understanding of the life history requirements and marine ecology of this species.

New Jersey↗
USGS1999

Fire and aquatic ecosystems in forested biomes of North America

Synthesis of the literature suggests that physical, chemical, and biological elements of a watershed interact with long‐term climate to influence fire regime, and that these factors, in concordance with the postfire vegetation mosaic, combine with local‐scale weather to govern the trajectory and magnitude of change following a fire event. Perturbation associated with hydrological processes is probably the primary factor influencing postfire persistence of fishes, benthic macroinvertebrates, and diatoms in fluvial systems. It is apparent that salmonids have evolved strategies to survive perturbations occurring at the frequency of wildland fires (10°–10 2 years), but local populations of a species may be more ephemeral. Habitat alteration probably has the greatest impact on individual organisms and local populations that are the least mobile, and reinvasion will be most rapid by aquatic organisms with high mobility. It is becoming increasingly apparent that during the past century fire suppression has altered fire regimes in some vegetation types, and consequently, the probability of large stand‐replacing fires has increased in those areas. Current evidence suggests, however, that even in the case of extensive high‐severity fires, local extirpation of fishes is patchy, and recolonization is rapid. Lasting detrimental effects on fish populations have been limited to areas where native populations have declined and become increasingly isolated because of anthropogenic activities. A strategy of protecting robust aquatic communities and restoring aquatic habitat structure and life history complexity in degraded areas may be the most effective means for insuring the persistence of native biota where the probability of large‐scale fires has increased.

Transactions of the American Fisheries Society↗
USGS2000

Physiological status of naturally reared juvenile spring chinook salmon in the Yakima River: Seasonal dynamics and changes associated with smolting

Two year-classes of juvenile spring chinook salmon Oncorhynchus tshawytscha from the Yakima River, Washington, were sampled from July (3-4 months postemergence) through May (yearling smolt out-migration). Physiological characters measured included liver glycogen, body lipid, gill Na+-K+ ATPase, plasma thyroxine (T4), and plasma insulin-like growth factor-I (IGF-I). Distinct physiological changes were found that corresponded to season. Summer and fall were characterized by relatively high body lipid and condition factor. Winter was characterized by decreases in body lipid, condition factor, and plasma hormones. An increase in condition factor and body lipid was found in February and March. Finally, April and May were characterized by dramatic changes characteristic of smolting, including increased gill Na+-K+ ATPase activity, plasma T4, and IGF-I and decreased condition factor, body lipid, and liver glycogen. These results create a physiological template for juvenile spring chinook salmon in the drainage that provides a baseline for comparison with other years, populations, and life history types. In addition, this baseline provides a standard for controlled laboratory experiments and a target for fish culturists who rear juvenile spring chinook salmon for release from conservation hatcheries. The implications of these results for juvenile chinook salmon ecology and life history are discussed.

Washington↗
USGS2000

Reduction in recruitment of white bass in Lake Erie after invasion of white perch

Recruitment to the adult population of white bass Morone chrysops in Lake Erie sharply declined during the early 1980s. To explain this phenomenon, we formulated the following four hypotheses: (1) the biological characteristics of adult spawners changed during the early 1980s, so that the ability to produce eggs decreased; (2) the decrease in phosphorus loadings to Lake Erie during the 1970s resulted in a lower abundance of crustacean zooplankton and thus in reduced survival of age-0 white bass; (3) the increase in the population of adult walleyes Stizostedion vitreum in Lake Erie during the 1970s and 1980s led to reduced survival of age-0 white bass; and (4) establishment of the white perch Morone americana population in Lake Erie during the early 1980s led to reduced survival of the early life stages of white bass. The growth, maturity, and fecundity of adults during the period 1981–1997 were compared with the same characteristics found by earlier studies. The mean length, weight, and condition factors that we calculated were higher than those reported for Lake Erie in 1927–1929 for all age groups examined, and white bass in Lake Erie matured at an earlier age during 1981–1997 than during 1927–1929. Fecundity estimates ranged from 128,897 to 1,049,207 eggs/female and were similar to estimates from other populations. Therefore, the first hypothesis was rejected. With respect to the second hypothesis, zooplankton surveys conducted during 1970 and 1983–1987 indicated that the abundance of crustacean zooplankton in Lake Erie did not change between the two time periods. However, these results were not conclusive because only a single-year survey was conducted before 1980. Based on walleye diet studies and estimates of walleye population size, walleye predation pressure on age-0 white bass in Lake Erie during 1986–1988 was just slightly higher than that during 1979–1981. Thus, such pressure can explain only a minor portion of the reduction in white bass recruitment. To test the fourth hypothesis, intervention analysis was applied to the long-term abundance series for white bass. The abundance of age-0 white bass in Lake Erie between 1982 and 1997 was significantly lower than that between 1969 and 1981. The catch per unit effort of adult white bass in commercial trap nets between 1987 and 1997 was significantly lower than it was before 1987. Moreover, the period of reduced recruitment for white bass in Oneida Lake, New York, which extends from 1955 to the present, coincides with occupation of the lake by white perch. Thus, of the four hypotheses entertained, the most plausible explanation for the reduction in white bass recruitment in Lake Erie is that white perch reduced the survival of white bass during its early life history.

Michigan, New York, Ohio, Ontario, Pennsylvania↗
USGS2002

Identification of steelhead and resident rainbow trout progeny in the Deschutes River, Oregon, revealed with otolith microchemistry

Comparisons of strontium:calcium (Sr:Ca) ratios in otolith primordia and freshwater growth regions were used to identify the progeny of steelhead Oncorhynchus mykiss (anadromous rainbow trout) and resident rainbow trout in the Deschutes River, Oregon. We cultured progeny of known adult steelhead and resident rainbow trout to confirm the relationship between Sr:Ca ratios in otolith primordia and the life history of the maternal parent. The mean (??SD) Sr:Ca ratio was significantly higher in the otolith primordia of the progeny of steelhead (0.001461 ?? 0.00029; n = 100) than in those of the progeny of resident rainbow trout (0.000829 ?? 0.000012; n = 100). We used comparisons of Sr:Ca ratios in the primordia and first-summer growth regions of otoliths to determine the maternal origin of unknown O. mykiss juveniles (n = 272) collected from rearing habitats within the main-stem Deschutes River and tributary rearing habitats and thus to ascertain the relative proportion of each life history morph in each rearing habitat. Resident rainbow trout fry dominated the bi-monthly samples collected from main-stem rearing habitats between May and November 1995. Steelhead fry dominated samples collected from below waterfalls on two tributaries in 1996 and 1998.

Transactions of the American Fisheries Society↗
USGS1993

Genetic comparison of naturally spawned and artificially propagated Lake Ontario lake trout fry: Evaluation of a stocking strategy for species rehabilitation

Two strategies have been used in the effort to restore lake trout Salvelinus namaycush to Lake Ontario. First, lake trout strains from multiple wild and hatchery sources have been stocked to maximize genetic variability in the lake, Second, a unique hatchery “strain” of fish to be stocked was created each year with gametes collected from adult, hatchery‐origin fish that had survived to maturity after being stocked into Lake Ontario. Several hatchery strains may be represented among the adults captured and used to propagate this unique strain, termed the “Ontario strain.” The “Ontario strain” may have a genetically based potential for enhanced survival over other strains stocked in Lake Ontario because it is composed of the progeny of fish that have survived from the yearling to the adult life stage, Unlike naturally spawned fish, however, the “Ontario strain” has been shielded from natural selection during the critical period of mortality from spawning through the first year of life, The purpose of this study was to determine whether the “Ontario strain” was genetically representative of the wild fry produced in the lake, We examined the strain composition of three year‐classes of wild‐caught fry and six year‐classes of the “Ontario strain” using allozyme data with mixed‐stock analysis. The hatchery and wild fry were genetically dissimilar. In addition, the composition of the “Ontario strain” changed from predominantly Seneca strain in 1983–1984 to predominantly Superior and Killala strains from 1983 to 1989. Mixed‐stock estimates indicated that in contrast to the hatchery‐reared fry, strain composition of wildcaught fry did not vary greatly from year to year. Progeny of Seneca × Seneca crosses were the predominant fry in the three year‐classes of wild fry. The genetic dissimilarity between the “Ontario strain” fry and wild‐caught fry could be caused by differential mortality among the wild fry between spawning and fry emergence or by differential vulnerability of strains to the gill‐net sampling used to capture adults for gamete collection. Based on these results, the development of a new hatchery brood stock from wild‐caught fry is recommended as an alternative to the collection and propagation of gametes from mature hatchery‐origin lake trout. In addition, the composition of the hatchery strains stocked should be altered to emphasize those strains that reproduce successfully. Both options should be considered in order to speed the rehabilitation process.

Lake Ontario↗
USGS2004

Dietary uptake of polychlorinated biphenyls (PCBs) by rainbow trout

The presence of detectable levels of polychlorinated biphenyls (PCBs) in commercially produced fish feed has raised a concern about the degree of biomagnification of these contaminants in hatchery-reared trout. Our objectives were to (1) define the relationship between concentrations of PCBs in fish feed and in fish tissue and (2) estimate the relative contributions of feed and hatchery supply water to PCB concentrations in fish. We conducted a 6-month feeding trial with fingerling rainbow trout Oncorhynchus mykiss fed commercial diets with four concentrations of PCBs: a low-PCB diet (69 ng/g); a typical commercial diet (126 ng/g); and the typical diet spiked with PCBs at two levels (220 and 280 ng/g). The concentrations of PCBs in fillets after 1 month were commensurate with those in the feeds and remained relatively stable for the next 5 months; mean PCB concentrations in fillets ranged from 54 to 94 ng/g. Low levels of PCBs were detected in the hatchery supply water. We used the concentrations of PCBs in the feeds, absorption rates of PCBs, and two different rates of PCB depuration to estimate the potential uptake of PCBs from supply water. When we used a low depuration rate (half-life = 219 d), the computed body burdens of PCBs could be entirely attributed to the feeds. When a high depuration rate (half-life = 66 d) was used, some uptake of PCBs from the supply water was likely, but most of the total body burden originated from the feeds. We concluded that rainbow trout fed a diet with 126 ng/g PCBs would have a PCB concentration of about 60 ng/g in their fillets, which is high enough to warrant issuance of a consumption advisory (no more than one meal of fish per week) under a protocol adopted by some Great Lakes states.

North American Journal of Aquaculture↗
USGS2008

Linking landscapes and habitat suitability scores for diadromous fish restoration in the susquehanna river basin

Dams within the Susquehanna River drainage, Pennsylvania, are potential barriers to migration of diadromous fishes, and many are under consideration for removal to facilitate fish passage. To provide useful input for prioritizing dam removal, we examined relations between landscape-scale factors and habitat suitability indices (HSIs) for native diadromous species of the Susquehanna River. We used two different methods (U.S. Fish and Wildlife Service method: Stier and Crance [1985], Ross et al. [1993a, 1993b, 1997], and Pardue [1983]; Pennsylvania State University method: Carline et al. [1994]) to calculate HSIs for several life stages of American shad Alosa sapidissima, alewives Alosa pseudoharengus, and blueback herring Alosa aestivalis and a single HSI for American eels Anguilla rostrata based on habitat variables measured at transects spaced every 5 km on six major Susquehanna River tributaries. Using geographical information systems, we calculated land use and geologic variables upstream from each transect and associated those data with HSIs calculated at each transect. We then performed canonical correlation analysis to determine how HSIs were linked to geologic and land use factors. Canonical correlation analysis identified the proportion of watershed underlain by carbonate rock as a positive correlate of HSIs for all species and life stages except American eels and juvenile blueback herring. We hypothesize that potential mechanisms linking carbonate rock to habitat suitability include increased productivity and buffering capacity. No other consistent patterns of positive or negative correlation between landscape-scale factors and HSIs were evident. This analysis will be useful for prioritizing removal of dams in the Susquehanna River drainage, because it provides a broad perspective on relationships between habitat suitability for diadromous fishes and easily measured landscape factors. This approach can be applied elsewhere to elucidate relationships between fine- and coarse-scale variables and suitability of habitat for fishes. ?? Copyright by the American Fisheries Society 2008.

North American Journal of Fisheries Management↗