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USGS2004

Quantifying the combined effects of attempt rate and swimming capacity on passage through velocity barriers

The ability of fish to migrate past velocity barriers results from both attempt rate and swimming capacity. Here, I formalize this relationship, providing equations for estimating the proportion of a population successfully passing a barrier over a range of distances and times. These equations take into account the cumulative effect of multiple attempts, the time required to stage those attempts, and both the distance traversed on each attempt and its variability. I apply these equations to models of white sucker (Catostomus commersoni) and walleye (Stizostedion vitreum) ascending a 23-m-long flume against flows ranging from 1.5 to 4.5 m??s-1. Attempt rate varied between species, attempts, and over time and was influenced by hydraulic variables (velocity of flow and discharge). Distance of ascent was primarily influenced by flow velocity. Although swimming capacity was similar, white sucker had greater attempt rates, and consequently better passage success, than walleye. Over short distances, models for both species predict greater passage success against higher velocities owing to the associated increased attempt rate. These results highlight the importance of attraction to fish passage and the need for further investigation into the hydraulic and other environmental conditions required to simultaneously optimize both attempt rate and passage success.

Canadian Journal of Fisheries and Aquatic Sciences↗

USGS2004

Ecological correlates of fish movement in a network of Virginia streams

Identifying factors that influence fish movement is a key step in predicting how populations respond to environmental change. Using mark-recapture (four species) and trap capture (eight species) data, we examined relationships between three attributes of movement and 15 ecological variables. The probability of emigrating from a reach was positively related to intermittency (one species) and body size (one species) and negatively related to distance from the mainstem creek (two species) and habitat complexity (one species). The number of fish moving upstream through traps was positively related to increases in flow (five species), day length (three species), and water temperature (two species); the number moving through downstream traps was positively associated with increases in flow (three species). Distance moved was greater for fish moving through unsuitable reaches (one species). Floods have a pervasive effect on fish movement, and human activities that affect flows will have widespread implications. The importance of other factors varies interspecifically, which may translate into variation in persistence and colonization rates. For example, species that exhibit reach fidelity in complex habitats may increase movement if habitats are homogenized. These species may suffer population declines because of the cost of increased movement and may ultimately be replaced by ecological generalists.

Canadian Journal of Fisheries and Aquatic Sciences↗

USGS2004

Migration and rearing histories of chinook salmon (Oncorhynchus tshawytscha) determined by ion microprobe Sr isotope and Sr/Ca transects of otoliths

Strontium isotope and Sr/Ca ratios measured in situ by ion microprobe along radial transects of otoliths of juvenile chinook salmon ( Oncorhynchus tshawytscha ) vary between watersheds with contrasting geology. Otoliths from ocean-type chinook from Skagit River estuary, Washington, had prehatch regions with 87 Sr/ 86 Sr ratios of ~0.709, suggesting a maternally inherited marine signature, extensive fresh water growth zones with 87 Sr/ 86 Sr ratios similar to those of the Skagit River at ~0.705, and marine-like 87 Sr/ 86 Sr ratios near their edges. Otoliths from stream-type chinook from central Idaho had prehatch 87 Sr/ 86 Sr ratios ≥0.711, indicating that a maternal marine Sr isotopic signature is not preserved after the ~1000- to 1400-km migration from the Pacific Ocean. 87 Sr/ 86 Sr ratios in the outer portions of otoliths from these Idaho juveniles were similar to those of their respective streams (~0.7080.722). For Skagit juveniles, fresh water growth was marked by small decreases in otolith Sr/Ca, with increases in Sr/Ca corresponding to increases in 87 Sr/ 86 Sr with migration into salt water. Otoliths of Idaho fish had Sr/Ca radial variation patterns that record seasonal fluctuation in ambient water Sr/Ca ratios. The ion microprobe's ability to measure both 87 Sr/ 86 Sr and Sr/Ca ratios of otoliths at high spatial resolution in situ provides a new tool for studies of fish rearing and migration.

Canadian Journal of Fisheries and Aquatic Sciences↗

USGS2005

The impact of introduced round gobies (Neogobius melanostomus) on phosphorus cycling in central Lake Erie

We used an individual-based bioenergetic model to simulate the phosphorus flux of the round goby (Neogobius melanostomus) population in central Lake Erie during 1995-2002. Estimates of round goby diet composition, growth rates, and population abundance were derived from field sampling. As an abundant introduced fish, we predicted that round gobies would influence phosphorus cycling both directly, through excretion, and indirectly, through consumption of dreissenid mussels, whose high mass-specific phosphorus excretion enhances recycling. In 1999, when age-1+ round gobies reached peak abundance near 350 million (2.4 kg??ha-1), annual phosphorus excretion was estimated at 7 t (1.4 ?? 10-3 mg P??m-2??day -1). From an ecosystem perspective, however, round gobies excreted only 0.4% of the phosphorus needed by the benthic community for primary production. Indirectly, round gobies consumed <0.2% of dreissenid population biomass, indicating that round gobies did not reduce nutrient availability by consuming dreissenids. Compared with previous studies that have revealed introduced species to influence phosphorus cycling, round gobies likely did not attain a sufficiently high biomass density to influence phosphorus cycling in Lake Erie. ?? 2005 NRC Canada.

Canadian Journal of Fisheries and Aquatic Sciences↗

USGS2005

Evidence for cumulative temperature as an initiating and terminating factor in downstream migratory behavior of Atlantic salmon (Salmo salar) smolts

Temperature control of Atlantic salmon (Salmo salar) smolt migration was tested using a novel technique allowing nearly continuous monitoring of behavior with complete control over environmental conditions. Parr and presmolts were implanted with passive integrated transponder tags, placed in simulated streams, and monitored for upstream and downstream movements. Beginning 18 April, temperature was increased 1??C every third day (advanced), fourth day (ambient), and tenth day (delayed). Smolt downstream movements were initially low, peaked in mid-May, and subsequently declined under all conditions. Parr downstream movements were significantly lower than those of smolts in all treatments (0.8 ?? 0.5 movement??day-1 versus 26.5 ?? 4.5 movements??day-1, mean ?? SE) and showed no increase. At delayed temperatures, smolts sustained downstream movements through July; those under ambient and advanced conditions ceased activity by mid-June. Initiation and termination of downstream movements occurred at significantly different temperatures but at the same number of degree-days in all treatments. Physiological changes associated with smolting (gill Na+,K +-ATPase activity and plasma thyroxine) were coincident with behavioral changes. This is the first evidence of a behavioral component to the smolt window. We found that temperature experience over time is more relevant to initiation and termination of downstream movement than a temperature threshold. ?? 2005 NRC Canada.

Canadian Journal of Fisheries and Aquatic Sciences↗

USGS2005

Stream acidification and mortality of brook trout (Salvelinus fontinalis) in response to timber harvest in Catskill Mountain watersheds, New York, USA

Effects of clear-cut and timber-stand improvement (TSI) harvests on water chemistry and mortality of caged brook trout (Salvelinus fontinalis) were evaluated in a study of three Catskill Mountain streams, 1994-2000. Harvests removed 73% of tree basal area (BA) from a clearcut subbasin, 5% BA from a TSI subbasin, and 14% BA at a site below the confluence of both streams. A fourth nonharvested site served as a control. Water quality and trout mortality were affected only in the clearcut stream. Acidity and concentrations of nitrate and inorganic monomeric aluminum (Alim) increased sharply during high flows after the first growing season (fall 1997). Acid-Alim episodes were severe during this period and decreased steadily in magnitude and duration thereafter. All trout at this site died within 7 days during spring 1998 and 85% died during spring 1999. Only background mortality was observed in other years at this site and at the other three sites during all tests. The absence of mortality in TSI watersheds indicates that limited harvests should not harm brook trout populations in acid-sensitive streams. Effects of tree harvests on fish communities are of concern, however, because many stream-dwelling species are more sensitive to acidified waters than brook trout. ?? 2005 NRC.

Canadian Journal of Fisheries and Aquatic Sciences↗

USGS2005

Ecology of the Lake Huron fish community, 1970-1999

We review the status of the Lake Huron fish community between 1970 and 1999 and explore the effects of key stressors. Offshore waters changed little in terms of nutrient enrichment, while phosphorus levels declined in inner Saginaw Bay. Introduced mussels ( Dreissena spp.) proliferated and may have caused a decline in Diporeia spp. This introduction could have caused a decline in lake whitefish ( Coregonus clupeaformis ) growth and condition, with serious repercussions for commercial fisheries. Bythotrephes , an exotic predatory cladoceran, and other new exotics may be influencing the fish community. Sea lampreys ( Petromyzon marinus ) remained prevalent, but intensive control efforts on the St. Mary's River may reduce their predation on salmonines. Overfishing was less of a problem than in the past, although fishing continued to reduce the amount of lake trout ( Salvelinus namaycush ) spawning biomass resulting from hatchery-reared fish planted to rehabilitate this species. Massive stocking programs have increased the abundance of top predators, but lake trout were rehabilitated in only one area. Successful lake trout rehabilitation may require lower densities of introduced pelagic prey fish than were seen in the 1990s, along with continued stocking of hatchery-reared lake trout and control of sea lamprey. Such reductions in prey fish could limit Pacific salmon ( Oncorhynchus spp.) fisheries.

Canadian Journal of Fisheries and Aquatic Sciences↗

USGS2006

Forecasting effects of climate change on Great Lakes fisheries: models that link habitat supply to population dynamics can help

Future changes to climate in the Great Lakes may have important consequences for fisheries. Evidence suggests that Great Lakes air and water temperatures have risen and the duration of ice cover has lessened during the past century. Global circulation models (GCMs) suggest future warming and increases in precipitation in the region. We present new evidence that water temperatures have risen in Lake Erie, particularly during summer and winter in the period 19652000. GCM forecasts coupled with physical models suggest lower annual runoff, less ice cover, and lower lake levels in the future, but the certainty of these forecasts is low. Assessment of the likely effects of climate change on fish stocks will require an integrative approach that considers several components of habitat rather than water temperature alone. We recommend using mechanistic models that couple habitat conditions to population demographics to explore integrated effects of climate-caused habitat change and illustrate this approach with a model for Lake Erie walleye ( Sander vitreum ). We show that the combined effect on walleye populations of plausible changes in temperature, river hydrology, lake levels, and light penetration can be quite different from that which would be expected based on consideration of only a single factor.

Canadian Journal of Fisheries and Aquatic Sciences↗

USGS2006

The influence of fall-spawning coho salmon (Oncorhynchus kisutch) on growth and production of juvenile coho salmon rearing in beaver ponds on the Copper River Delta, Alaska

This study examined the influence of fall-spawning coho salmon (Oncorhynchus kisutch) on the density, growth rate, body condition, and survival to outmigration of juvenile coho salmon on the Copper River Delta, Alaska, USA. During the fall of 1999 and 2000, fish rearing in beaver ponds that received spawning salmon were compared with fish from ponds that did not receive spawners and also with fish from ponds that were artificially enriched with salmon carcasses and eggs. The response to spawning salmon was variable. In some ponds, fall-spawning salmon increased growth rates and improved the condition of juvenile coho salmon. The enrichment with salmon carcasses and eggs significantly increased growth rates of fish in nonspawning ponds. However, there was little evidence that the short-term growth benefits observed in the fall led to greater overwinter growth or survival to outmigration when compared with fish from the nonspawning ponds. One potential reason for this result may be that nutrients from spawning salmon are widely distributed across the delta because of hydrologic connectivity and hyporheic flows. The relationship among spawning salmon, overwinter growth, and smolt production on the Copper River Delta does not appear to be limited entirely to a simple positive feedback loop. ?? 2006 NRC.

Canadian Journal of Fisheries and Aquatic Sciences↗

USGS2006

Long-term trends of bloater ( Coregonus hoyi ) recruitment in Lake Michigan: evidence for the effect of sex ratio

Long-term population trends are generally explained by factors extrinsic (e.g., climate, predation) rather than intrinsic (e.g., genetics, maternal effects) to the population. We sought to understand the long-term population dynamics of an important native Lake Michigan prey fish, the bloater Coregonus hoyi . Over a 38-year time series, three 10- to 15-year phases occurred (poor, excellent, and then poor recruitment) without high interannual variability within a particular phase. We used dynamic linear models to determine whether extrinsic (winter and spring temperature, alewife predator densities) or intrinsic factors (population egg production, adult condition, adult sex ratio) explained variation in recruitment. Models that included population egg production, sex ratio, winter and spring temperature, and adult bloater condition explained the most variation. Of these variables, sex ratio, which ranged from 47% to 97% female across the time series, consistently had the greatest effect: recruitment declined with female predominance. Including biomass of adult alewife predators in the models did not explain additional variation. Overall our results indicated that bloater recruitment is linked to its sex ratio, but understanding the underlying mechanisms will require additional efforts.

Canadian Journal of Fisheries and Aquatic Sciences↗

USGS2006

Seasonal effects of the zebra mussel ( Dreissena polymorpha ) on sediment denitrification rates in Pool 8 of the Upper Mississippi River

Zebra mussels ( Dreissena polymorpha ) have altered the structure of invaded ecosystems and exhibit characteristics that suggest they may influence ecosystem processes such as nitrogen (N) cycling. We measured denitrification rates seasonally on sediments underlying zebra mussel beds collected from the impounded zone of Navigation Pool 8 of the Upper Mississippi River. Denitrification assays were amended with nutrients to characterize variation in nutrient limitation of denitrification in the presence or absence of zebra mussels. Denitrification rates at zebra mussel sites were high relative to sites without zebra mussels in February 2004 (repeated measures analysis of variance (RM ANOVA), p = 0.005), potentially because of high NO 3 -N variability from nitrification of high NH 4 + zebra mussel waste. Denitrification rates were highest in June 2003 (RM ANOVA, p < 0.001), corresponding with the highest NO 3 -N concentrations during the study (linear regression, R 2 = 0.72, p < 0.001). Denitrification was always N-limited, but sites without zebra mussels showed the strongest response to N amendments relative to sites with zebra mussels (two-way ANOVA, p ≤ 0.01). Examining how zebra mussels influence denitrification rates will aid in developing a more complete understanding of the impact of zebra mussels and more effective management strategies of eutrophic waters.

Upper Mississippi River↗

USGS2006

Ontogenetic dynamics of mercury accumulation in Northwest Atlantic sea lamprey (Petromyzon marinus)

We examined the ontogenetic dynamics of mercury accumulation in sea lamprey (Petromyzon marinus) from the Connecticut River, USA. Mercury concentrations in eggs (mean 84 ng??g-1 wet weight) were lowest of all life stages and correlated to concentrations in females. There was a higher rate of maternal transfer of mercury to eggs compared with teleosts. Ammocoetes had high mercury concentrations for their trophic level (e.g., mean of age-4 ammocoetes 492 ng??g-1 wet weight). A further investigation of four streams showed that ammocoetes reflected the level of contamination in their nursery streams. Concentrations of mercury decreased during metamorphosis from ammocoete to adult. Mercury concentrations in adults ranged from 83 to 942 ng??g-1 wet weight and, unlike teleosts, showed no relation to sex, length, or weight. We provide evidence from stable isotope analyses that this high variability is due to feeding ecology. There are fundamental differences in mercury accumulation between sea lamprey and teleosts. ?? 2006 NRC Canada.

Canadian Journal of Fisheries and Aquatic Sciences↗

USGS2006

Changes in seasonal energy dynamics of alewife ( Alosa pseudoharengus ) in Lake Michigan after invasion of dreissenid mussels

The dreissenid mussel invasion of Lake Michigan during the 1990s has been linked to a concomitant decrease in the abundance of the amphipod Diporeia . We tracked the seasonal energy dynamics of alewife ( Alosa pseudoharengus ) in Lake Michigan during 2002–2004 and compared our findings with previously published results for years 1979–1981. Adult alewife energy density exhibited a pronounced seasonal cycle during both the pre-invasion and post-invasion periods, with energy density in October or November nearly twice as high as that in early summer. However, on average, adult alewife energy density was 23% lower during the post-invasion period compared with the pre-invasion period. This significant decline in energy density was attributable to decreased importance of Diporeia in adult alewife diet. In contrast, energy density of juvenile alewives did not significantly differ between the pre-invasion and post-invasion periods. To attain a weight of 8 kg by age 4, bioenergetics modeling indicated that a Chinook salmon ( Oncorhynchus tshawytscha ) in Lake Michigan would have to consume 22.1% more alewives during the post-invasion period compared with the pre-invasion period.

Canadian Journal of Fisheries and Aquatic Sciences↗

USGS2006

Assessing possible thermal rearing restrictions for juvenile coho salmon (Oncorhynchus kisutch) through thermal infrared imaging and in-stream monitoring, Redwood Creek, California

We quantified patterns in stream temperature in a northern coastal California river using thermal infrared (TIR) imaging and in-stream monitoring and related temperature patterns to the historical and present distributions of juvenile coho salmon (Oncorhynchus kisutch). In Redwood Creek, California, water temperature increased from the headwaters to about 60 km downstream, then gradually decreased over the next 40 km as the river approaches the Pacific Ocean. Despite the lack of fish migration barriers, juvenile coho are currently only observed in the downstream-most 20 km, whereas historically they were found in 90 km of river channel. Maximum daily temperatures and duration of elevated stream temperatures were not significantly different in the headwater and downstream reaches but were significantly higher in the 50 km long intervening reach, where maximum weekly maximum temperatures ranged from 23 to 27??C. An increase in stream temperatures in the middle basin during the last three decades as a result of channel aggradation, widening, and the removal of large riparian conifers may play an important role in restricting juvenile coho to one-fifth of their historical range. ?? 2006 NRC.

Canadian Journal of Fisheries and Aquatic Sciences↗

USGS2006

Persistent disturbance by commercial navigation afters the relative abundance of channel-dwelling fishes in a large river

We provide the first evidence for chronic effects of disturbance by commercial vessels on the spatial distribution and abundance of fishes in the channels of a large river. Most of the world's large rivers are intensively managed to satisfy increasing demands for commercial shipping, but little research has been conducted to identify and alleviate any adverse consequences of commercial navigation. We used a combination of a gradient sampling design incorporating quasicontrol areas with Akaike's information criterion (AIC)-weighted model averaging to estimate effects of disturbances by commercial vessels on fishes in the upper Mississippi River. Species density, which mainly measured species evenness, decreased with increasing disturbance frequency. The most abundant species - gizzard shad (Dorosoma cepedianum) and freshwater drum (Aplodinotus grunniens) - and the less abundant shovelnose sturgeon (Scaphirhynchus platorhynchus) and flathead catfish (Pylodictis olivaris) were seemingly unaffected by traffic disturbance. In contrast, the relative abundance of the toothed herrings (Hiodon spp.), redhorses (Moxostoma spp.), buffaloes (Ictiobus spp.), channel catfish (Ictalurus punctatus), sauger (Sander canadensis), and white bass (Morone chrysops) decreased with increasing traffic in the navigation channel. We hypothesized that the combination of alteration of hydraulic features within navigation channels and rehabilitation of secondary channels might benefit channel-dependent species. ?? 2006 NRC.

Canadian Journal of Fisheries and Aquatic Sciences↗

USGS2006

Water color affects the stratification, surface temperature, heat content, and mean epilimnetic irradiance of small lakes

The effects of water color on lake stratification, mean epilimnetic irradiance, and lake temperature dynamics were examined in small, north-temperate lakes that differed widely in water color (1.5-19.8 m -1). Among these lakes, colored lakes differed from clear lakes in the following ways: (i) the epilimnia were shallower and colder, and mean epilimnetic irradiance was reduced; (ii) the diel temperature cycles were more pronounced; (iii) whole-lake heat accumulation during stratification was reduced. The depth of the epilimnion ranged from 2.5 m in the clearest lake to 0.75 m in the most colored lake, and 91% of the variation in epilimnetic depth was explained by water color. Summer mean morning epilimnetic temperature was ???2??C cooler in the most colored lake compared with the clearest lake. In clear lakes, the diel temperature range (1.4 ?? 0.7??C) was significantly (p = 0.01) less than that in the most colored lake (2.1 ?? 1.0??C). Change in whole-lake heat content was negatively correlated with water color. Increasing water color decreased light penetration more than thermocline depth, leading to reduced mean epilimnetic irradiance in the colored lakes. Thus, in these small lakes, water color significantly affected temperature, thermocline depth, and light climate. ?? 2006 NRC.

Canadian Journal of Fisheries and Aquatic Sciences↗

USGS2006

Long-term changes of the Lake Michigan fish community following the reduction of exotic alewife ( Alosa pseudoharengus )

We used our long-term annual bottom trawl survey (1973–2004) in Lake Michigan to reveal the response of the native fish community to the biological control of a dominant exotic fish, alewife ( Alosa pseudoharengus ), as well as to changes in total phosphorus and salmonine biomass. Through nonmetric multidimensional scaling, we documented a 1970s community largely dominated by alewife, and then a shift to a community dominated by several native species during the 1980s through 1990s, when alewife remained at relatively low levels. We argue that the recovery of burbot ( Lota lota ), deepwater sculpin ( Myoxocephalus thompsonii ), and yellow perch ( Perca flavescens ) was partially or fully aided by the alewife reduction. We argue that changes in phosphorus or salmonines were not directly related to abundance increases of native species. An additional community shift occurred during 1999–2004, which coincided with a reduction in species richness and total fish biomass in our trawl. The mechanisms underlying this latest shift may be related to reductions in nutrients, but further research is required. The restoration of the native fish community has been incomplete, however, as emerald shiner ( Notropis atherinioides ), cisco ( Coregonus artedii ), and lake trout ( Salvelinus namaycush ) have yet to demonstrate recovery.

Canadian Journal of Fisheries and Aquatic Sciences↗

USGS2011

Mysid and fish zooplanktivory in Lake Ontario: quantification of direct and indirect effects

Mysis relicta and planktivorous fish feed on zooplankton in Lake Ontario and form a trophic triangle that includes intraguild predation by fish on mysids. Thus, fish affect zooplankton both directly and indirectly. To evaluate the importance of alewife (Alosa pseudoharengus), rainbow smelt (Osmerus mordax), and mysids as zooplanktivores in Lake Ontario, we measured abundances and distributions, assessed diets, and computed mysid and fish consumption rates based on bioenergetics models. We further estimated indirect effects by comparing clearance rates given observed and potential mysid distributions. Estimated consumption rates varied widely with season and water depth and ranged between 2.6 x 10-3 and 1.3 gm-2day-1 for mysids and between 1.4 x 10-3 and 0.5 gm-2day-1 for fish, representing a daily removal of zooplankton of up to 10.2%-day-1 and 2.0%-day-1 by mysids and fish, respectively. Mysid planktivory exceeded fish planktivory in May and August, but fish planktivory dominated in October. Estimated mysid planktivory rates were 2- to 90-fold lower than the potential rate if mysids moved to temperatures that maximized their predation rates, suggesting an indirect positive effect of fish on zooplankton.

Canadian Journal of Fisheries and Aquatic Sciences↗