bluuebunny/crossref_metadata_2025 huggingface dataset:
Country-rock contamination of marginal mafic granulites bordering the Nain Plutonic Suite: implications for mobilization of Sr during high-grade contact metamorphism
Authors: Royse K R , Noble S R , Tarney J , Cadman A C
Published: April 2011

The marginal mafic granulites that locally border the Nain Plutonic Suite (NPS) have a range of initial Nd-isotope ratios that overlap with that of the NPS anorthosites and associated Nain dykes. The similarity in Nd-isotope data suggests that gneissic Archaean country rocks have contaminated all the anorthosites, marginal mafic granulites, and dykes. Sr-isotope data for the mafic granulites and dykes support a country rock contamination scenario but preclude wholesale assimilation of rocks such as the host Archaean tonalite gneisses as the sole contaminant. Initial epsilonSrvalues of +10 to +403 and +0.9 to +242 for the mafic granulites and dykes, respectively, are significantly higher than values for NPS country rocks examined thus far. The elevated initial εSrvalues are therefore interpreted to result from the introduction of radiogenic Sr into the granulites and dykes via Sr-rich fluids, generated by the breakdown of Rb-rich mineral phases such as biotite in the country rocks during NPS.
Numerical modelling of the Laurentide Ice Sheet in the Baffin Island region: the role of a Cumberland Sound ice stream
Authors: Kaplan Michael R , Pfeffer W Tad , Sassolas Christophe , Miller Gifford H
Published: April 2011

A numerical model reconstruction was made of the northeastern Laurentide Ice Sheet in the Baffin Island - Foxe Basin region using geophysical, terrestrial, and marine geologic evidence for initial and boundary conditions. The simulated ice sheet consists of a Foxe Dome with additional smaller Hall and Amadjuak domes and a Penny Ice Divide. A specific objective was to determine boundary conditions that would allow advance of a marine-based low surface slope ice stream into and out of Cumberland Sound, a major marine embayment in the uplifted rim of the eastern Canadian Arctic (up to 1200 m deep), while maintaining ice free or nonsliding (e.g., cold-based) thin ice on adjacent plateaus of Cumberland Peninsula; this scenario accommodates interpretations based on terrestrial and marine studies in this region. After an initial ice-sheet configuration is placed on the eastern Arctic terrain, basal sliding is allowed in specified regions. Basal sliding below sea level and between the Foxe Dome and Cumberland Sound and a reasonable but critical initial ice sheet volume and dome surface elevation are needed to obtain advance along and out of Cumberland Sound. Rapid flow into Hudson Strait and along Cumberland Sound causes drawdown and a change in ice-sheet configuration. Although more Foxe Dome ice flows into western Hudson Strait than Cumberland Sound in the simulations, the latter may still have been an important conduit connecting the interior of the northeastern Laurentide Ice Sheet to the Labrador Sea, thereby affecting regional ice sheet dynamics, specifically ice surface elevations and flow paths.
Lithostratigraphy and paleomagnetism of pre-Fraser glacial deposits in south-central British Columbia
Authors: Lian Olav B , Barendregt R W , Enkin R J
Published: April 2011

Lithostratigraphic records spanning considerable parts of the Pleistocene were studied at three sites in south-central British Columbia. A sedimentary succession near Pavilion includes three distinctly different till units. While the surface till can be associated with the last glaciation (the Fraser Glaciation δ18O stage 2), the ages of the two older till units are presently unknown. However, optical dating of outwash silt resting on the oldest till indicates that this outwash unit and all the overlying units are younger than ~160 ka. In Big Bar Creek valley, about 50 km north of Pavilion, an aggradational sequence of indurated glaciofluvial sand, gravel, and till is exposed. A silt unit and a sand lens within an overlying till bed near the top of the section have reversed magnetization, indicating deposition prior to 780 ka, probably during the Matuyama chron. The Big Bar Creek sequence also includes glacio(?)fluvial sediments near the base that are normally magnetized, suggesting that they were deposited, at the latest, during the Jaramillo subchron (~1.0 Ma), but probably during the Gauss chron, before 2.6 Ma. Reversely magnetized glacio(?)fluvial gravel and sand also occur along Jesmond Road between the Marble Range and Edge Hills. These units give support for the development of at least one Cordilleran ice sheet in the Early Pleistocene or Late Pliocene.
First record of Seymouria (Vertebrata: Seymouriamorpha) from Early Permian fissure fills at Richards Spur, Oklahoma
Authors: Sullivan Corwin , Reisz Robert R
Published: April 2011

Isolated skeletal elements of the amphibian genus Seymouria were recently discovered at the Richards Spur locality near Fort Sill, Oklahoma, a prolific source of Early Permian tetrapod remains. Five of the seven described bones are of juvenile size and include three neural arches, a humerus, and a femur, whereas the other two are partial vertebrae, apparently adult. All seven are morphologically similar to equivalent skeletal elements in Seymouria specimens previously collected in Europe and North America, apart from features reflecting the early developmental stage of the juvenile bones. The femur and humerus are clearly distinct from those of other seymouriamorphs such as Ariekanerpeton and Kotlassia. The rarity of Seymouria at the Richards Spur locality implies that it was not a regular component of the fauna, and it is also associated with the less markedly terrestrial assemblage that consistently occurs at localities in the southwestern United States. However, its skeletal morphology and occurrence at terrestrial localities such as Richards Spur imply a primarily terrestrial, rather than an amphibious, mode of life. Conflicting biostratigraphic correlations imply that the exact age of the Richards Spur deposits is uncertain, and equivalence to the Arroyo Formation of Texas may be erroneous.
Structure and stratigraphy of the south flank of the Kisseynew Domain in the Trans-Hudson Orogen, Manitoba: implications for 1.845-1.77 Ga collision tectonics
Authors: Zwanzig Herman V
Published: April 2011

On the south flank of the Kisseynew Domain, orthogneisses derived from 1.92-1.85 Ga volcano-plutonic rocks are overlain by paragneisses (Burntwood and Missi groups) derived from 1.855-1.84 Ga marine turbidite and 1.845-1.83 Ga terrestrial clastic and volcanic rocks. The sediments in these groups are interpreted as having been shed into the Kisseynew paleobasin from an active margin bordering the Flin Flon Belt. The sedimentation apparently followed early microcontinental collision and accompanied the last arc magmatism in the Trans-Hudson Orogen. The sedimentary rocks and their basement were deformed into a complexly refolded stack of large recumbent folds. Premetamorphic F1 structures represent a fold and thrust system initiated during the sedimentation. These structures are interpreted as transported toward the Kisseynew Domain in the northeast and the hinterland in the southwest. F2 structures (~1.82 Ga) comprise westerly transported nappes. During 1.82-1.80 Ga high-grade metamorphism, the early structures were overturned, amplified, and refolded. Basement-cored culminations and sheet-like synforms of paragneiss were horizontally attenuated and transported south and southwest. North- and northeast-trending F4 folds and F5 faults formed after 1.79 Ga. The whole cycle of deformation is related to stages of continental collision between the internal (juvenile) zone of the Trans-Hudson Orogen and the three surrounding Archean cratons (Sask, Superior, and Hearne). The F4 upright folds and steep F5 faults are interpreted as the record of intracontinental transpression, strongly controlled by the Superior Craton boundary.
Major and trace element compositions and Sr-Nd-Pb systematics of crystalline rocks from the Dawson Range, Yukon, Canada
Authors: Selby David , Creaser Robert A , Nesbitt Bruce E
Published: April 2011

Geochemical (major, trace, and rare earth elements) and isotopic (Nd, Sr, and Pb) data of the Devono-Mississippian Wolverine Creek Metamorphic Suite, mid-Cretaceous Dawson Range batholith, mid-Cretaceous Casino Plutonic Suite, and Late Cretaceous plutons provide new information on the origin and evolution of the rocks from the Dawson Range in west-central Yukon, northern Canadian Cordillera. Isotopic and other geochemical data for the Wolverine Creek Metamorphic Suite metasedimentary rocks indicate that the detrital components were derived from two distinct provenances: (1) the North America craton, which contributed evolved felsic, upper crustal material; and (2) a calc-alkaline arc, which shed juvenile mafic-intermediate material. The geochemical affinity of the metaigneous rocks indicates that the Yukon-Tanana terrane represented a continental arc during Devonian-Mississippian times, with magmas derived from geochemically primitive sources and partial melting of the Yukon-Tanana terrane supracrustal rocks. The Dawson Range batholith likely represents crustally derived magmas from the Yukon-Tanana terrane during the mid-Cretaceous, with the contemporaneous Casino Plutonic Suite representing a late-stage fractionate of these magmas. The Late Cretaceous porphyry Cu mineralization is genetically related to plutons derived from mantle-source magmas related to active subduction.
Spatial and temporal trends in carbon storage of peatlands of continental western Canada through the Holocene
Authors: Vitt Dale H , Halsey Linda A , Bauer Ilka E , Campbell Celina
Published: April 2011

Peatlands of continental western Canada (Alberta, Saskatchewan, and Manitoba) cover 365 157 km2 and store 48.0 Pg of carbon representing 2.1% of the world's terrestrial carbon within 0.25% of the global landbase. Only a small amount, 0.10 Pg (0.2%) of this carbon, is currently stored in the above-ground biomass. Carbon storage in peatlands has changed significantly since deglaciation. Peatlands began to accumulate carbon around 9000 years ago in this region, after an initial deglacial lag. Carbon accumulation was climatically limited throughout much of continental western Canada by early Holocene maximum insolation. After 6000 BP, carbon accumulation increased significantly, with about half of current stores being reached by 4000 BP. Around 3000 BP carbon accumulation in continental western Canada began to slow as permafrost developed throughout the subarctic and boreal region and the current southern limit of peatlands was reached. Peatlands in continental western Canada continue to increase their total carbon storage today by 19.4 g m-2 year-1, indicating that regionally this ecosystem remains a large carbon sink.
40Ar/39Ar thermochronometric constraints on the tectonic evolution of the Clachnacudainn complex, southeastern British Columbia
Authors: Colpron Maurice , Price Raymond A , Archibald Douglas A
Published: April 2011

40Ar/39Ar thermochronometry from the Clachnacudainn complex indicates that the thermal evolution of the complex was controlled primarily by the intrusion of granitoid plutons in mid- and Late Cretaceous times. Hornblendes from the eastern part of the complex cooled below their Ar closure temperature (ca. 500°C) shortly after intrusion of the mid-Cretaceous plutons; those from the western part of the complex have latest Cretaceous cooling dates, indicating cooling of these hornblendes after intrusion of the leucogranite plutons at ca. 71 Ma. Micas from the southern Clachnacudainn complex exhibit a pattern of progressive cooling toward lower structural levels, where Late Cretaceous and younger intrusions occur. The occurrence of Late Cretaceous - Paleocene mica cooling dates in both the hanging wall and footwall of the Standfast Creek fault refutes the hypothesis that there has been significant Tertiary extensional exhumation of the Clachnacudainn complex along the Standfast Creek fault. Furthermore, the widespread distribution of Late Cretaceous - Paleocene mica cooling ages suggests that an important volume of Late Cretaceous - early Tertiary intrusive rocks must be present in the subsurface beneath the Clachnacudainn complex.
Neustonic postlarval American lobsters, Homarus americanus, in the western Gulf of Maine: spatial and interannual variations
Authors: Incze Lewis S , Aas Peter , Ainaire Terri , Bowen Marcia
Published: April 2011

We examined the seasonal abundance of postlarval (PL) (stage IV) American lobsters, Homarus americanus, from neuston samples from 1989 to 1995 at Johns Bay, Maine, and Seabrook, New Hampshire, located 150 km apart in the western Gulf of Maine. The postlarval season at these sites began between approximately days of the year 180 and 210 and ranged from about 35 to 70 days in duration. Within years, start and end dates were similar for the two sites. Maximum concentrations from single tows exceeded 100 PL·1000 m-2, but 85% or more of the positive tows had concentrations <15 PL·1000 m-2 and more than half had <5 PL·1000 m-2. These concentrations occurred at high levels of the stock, were the source for continued high recruitment in the 1990s, and thereby form a benchmark for future measurements. Only one of the seven years showed a major decline in seasonal abundance, and it occurred at both sites. Of the remaining years, three had nearly identical integrated abundances at both sites (approximately 200 PL· 1000 m-2·year-1). A survey in the western Gulf of Maine caught postlarvae out to 56 km offshore at concentrations similar to the coastal samples, indicating a broadly distributed source of potential recruits to the benthic population.
Temporal changes in harvesting dynamics of Canadian inshore fisheries for northern Atlantic cod, Gadus morhua
Authors: Hutchings Jeffrey A , Ferguson Mark
Published: April 2011

We quantified temporal changes in catch rate, fishing effort, and catch misreporting for two sectors of the fixed-gear fishery for Newfoundland's northern Atlantic cod, Gadus morhua, from 1980 to 1991, the year preceding the stock's commercial fishing moratorium. Over the 12-year period, fishermen reported catch rate declines of 40 and 75% in the trap and gillnet fisheries, respectively, associated with significant increases in nominal fishing effort. Additional changes to effort included smaller gillnet and trap mesh sizes, larger traps, longer soak times, and modifications to trap design to increase catch retention probabilities. Compared with the early 1980s, unreported catches among inshore fishermen may have trebled by the late 1980s and early 1990s due to longer gillnet soak times, increased gear selectivity for small fish, and declining availability of fish of marketable size. These patterns in harvesting dynamics are consistent with the hypothesis that the decline of northern cod was gradual and that increased rates of catch misreporting contributed to increases in fishing mortality. The concomitants of declining fixed-gear catch rate, increasing quantitative and qualitative fishing effort, increased selectivity for smaller fish, and increasing levels of unreported catches may represent general correlates of imminent fish stock collapses.
Assessing density-dependent establishment and dispersal: an example using caddisfly larvae
Authors: Kerans B L , Chesson Peter L , Stein Roy A
Published: April 2011

Density dependence in colonization is poorly understood. We studied colonization by a benthic, stream-dwelling caddisfly, Hydropsyche slossonae, through experiments varying conspecific densities and environmental conditions. A model of larval acceptance or rejection of a locality (dispersal from the locality) was developed and fitted to the data to estimate the relative strengths of density-dependent and density-independent processes underlying dispersal. In spring and fall, we varied density, substrate size, and current velocity in laboratory experiments and varied density in field experiments. In the laboratory, dispersal of fifth instars was always density dependent, but the strength of density dependence was highest in spring when the proportion dispersing was lowest. Dispersal in field experiments was density dependent only in spring. Proportion dispersing was highest under low flow. The model fit to laboratory data suggested that stronger density dependence in spring occurred because of a reduction in density-independent dispersal stimuli with no change in density-dependent stimuli. In contrast, a change in density-dependent stimuli did appear to cause differences between the proportions dispersing under the two flow regimes. The model reveals the potential for density-independent dispersal stimuli to modify the strength of density dependence detectable at the population level.
Using perceptions of data accuracy and empirical weighting of information: assessment of a recreational fish population
Authors: Merritt Margaret F , Quinn II Terrance J
Published: April 2011

Recreational fisheries management is often compromised by limited information of variable quality from several sources. We develop a form of catch-age analysis to combine uncertain information from creel surveys, age composition, and mark-recapture estimates of abundance. Four systems are used in weighting annual observations: equal, inverse of squared coefficients of variation (CV-2), perceptions of accuracy, and a combination of the latter two. The model is applied to a humpback whitefish (Coregonus pidschian) population in Alaska and evaluated for model fit, parameter uncertainty, conservative forecasts of exploitable abundance, and biological plausibility. The probability of forecasted stock abundance occurring below a threshold level defined by an agency management plan is evaluated for various recruitment and exploitation scenarios. The perception model is judged to be best with the use of the analytic hierarchy process, a decision-making technique. By incorporating perceptions into fisheries decision-making, beliefs in the accuracy of uncertain information are made explicit. In a conservative context, fishery management decisions should include reducing risk to the stock in the setting of harvest policy and in the selection of the assessment model.
Effects of riffle length on the short-term movement of fishes among stream pools
Authors: Lonzarich D G , Lonzarich M R , Warren Jr. M L
Published: April 2011

Recent research has suggested that the within-habitat dynamics of fish populations and assemblages can be affected by the spatial distribution of habitats within streams. In this study, we determined the extent to which pool isolation (length of riffles connecting adjacent pools) influenced fish movement in two Arkansas streams. We marked individuals from 12 pools assigned to two treatment categories: pools separated by long riffles (>50 m) and those separated by short riffles (<10 m). Repeatedly snorkeling pools for 3 days in 1995 and 1997, we discovered substantial emigration (>20%) and significant effects of riffle length. Total emigration from short-riffle pools was three times higher (29%) than movement from long-riffle pools (10%). Further, marked fish in short-riffle pools moved upstream and downstream with equal frequency, whereas fish in long-riffle pools moved twice as often downstream. Collectively, these results indicate significant effects of habitat spacing on short-term movement patterns by fish. In streams, where fish are distributed within a mosaic of habitats of varying quality, such movements may allow individuals to assess spatial variability in resource conditions (e.g., food, predators). Because land-use activities can alter habitat spacing, these findings have important implications for fish conservation in degraded streams.
Mercury concentrations in northern pike ( Esox lucius) from boreal lakes with logged, burned, or undisturbed catchments
Authors: Garcia Edenise , Carignan Richard
Published: April 2011

We measured total Hg and stable isotopes (δ13C and δ15N) in northern pike (Esox lucius) from 19 Boreal Shield lakes with undisturbed, logged, or burned watersheds. Average Hg level in standard 560-mm northern pike, on a dry weight basis, was significantly higher in logged lakes (3.4 µg·g-1) than in reference lakes (1.9 µg·g-1). Average Hg concentrations in burned lakes (3.0 µg·g -1) did not differ significantly from those in logged and references lakes. Concentrations of Hg normalized to trophic position determined from isotopic composition yielded similar results. Mercury levels were above the WHO safe consumption limit in all logged lakes. Mercury in northern pike was correlated with methyl mercury in zooplankton (+), total N (+), pH (-), alkalinity (-), sulfate (+), dissolved organic C loading (+), and light attenuation in lake water (+). Stepwise multiple regressions explained 79% of the variability in Hg in fish and included methyl mercury in zooplankton, pH, and sulfate as independent variables. Explained variability increased to 92% when a second-order lake with an exceptionally large drainage area was excluded. Our results suggest that extensive logging activities may disrupt the natural cycling of Hg in watersheds and increase Hg levels in the aquatic biota.
Acoustic estimates of zooplankton biomass and distribution: application of canonical correlation to scaling of multifrequency acoustic data
Authors: Coyle Kenneth O
Published: April 2011

A technique is presented that can be used to scale multifrequency acoustic data to estimates of wet weight biomass from concurrently collected zooplankton samples. The technique uses canonical correlation to identify those taxa that correlate with the acoustic data. Canoncial correlation is then used to compute scaling coefficients that can be used to convert transect data to biomass equivalents for the correlating taxa. Examples are offered to illustrate how the technique can identify euphausiid aggregates, pteropods, and larval fish. The technique can discriminate between taxa with gas bladders, taxa with shells, and fluid-filled taxa. It also has the advantage of quantifying the correlation between the target taxa and acoustic data, thus allowing the researcher to judge the usefulness of the acoustic data in characterizing the distribution and density of the zooplankton taxa.
Fatty acids in profundal benthic invertebrates and their major food resources in Lake Erken, Sweden: seasonal variation and trophic indications
Authors: Goedkoop Willem , Sonesten Lars , Ahlgren Gunnel , Boberg Merike
Published: April 2011

Fatty acid (FA) concentrations and their seasonal variations were quantified for profundal benthic invertebrates, surficial sediment, and sedimenting matter from Lake Erken, Sweden. Food quality for profundal zoobenthos, as indicated by the concentrations of long-chain polyunsaturated FA, ω3 FA, or eicosapentaenoic acid (EPA) in sediment and sedimenting matter, was highest in spring and autumn and markedly lower in summer. Surficial sediment was consistently lower in all FA than was sedimenting matter. Palmitoleic acid (16:1ω7) was the dominating FA in both sedimenting matter and sediment. In fauna samples, EPA, palmitic acid (16:0), palmitoleic acid, and vaccenic acid (18:1ω7) were among the dominant FA. Docosahexaenoic acid was found only in the predators Chaoborus and Procladius. Differences between functional feeding guilds were found for the diatom-indicating FA palmitoleic acid and the bacteria-specific FA isoseptadecanoic acid (17:0iso). Furthermore, principal components analysis showed marked differences in FA composition among taxa. These differences reflect the relative contribution of food from autotrophic (phytoplankton production) and heterotrophic sources (detrital food web) in profundal invertebrate taxa.
Effective population size of winter-run chinook salmon based on microsatellite analysis of returning spawners
Authors: Hedrick Philip W , Rashbrook Vanessa K , Hedgecock Dennis
Published: April 2011

We previously estimated the predicted effective population size for the endangered winter-run chinook salmon, Oncorhynchus tshawytscha, based on a number of assumptions, including random survival and return of released fish. Here we present data from actual returning spawners, identified to family by microsatellite loci, and calculate the observed effective population size. In 1994 and 1995, the observed effective population sizes were 93.6 and 78.2% of predicted values, respectively, suggesting that the numbers of returning fish were very close to random expectations in 1994 and less close to random in 1995. The ratio of the effective population size to the adult number, Ne/N, was greater than unity for 1994 and approximately 0.5 in 1995. The high ratio in 1994 reflects the success of the breeding protocol to equalize individual contributions and near random returns, while the lower number in 1995 appears to be the result of both less successful equalization and less close to random returns in that year. These findings provide an optimistic outlook for the success of this supplementation program and suggest that the overall effective population size has not been greatly reduced, since returning spawners represent a broad sample of parents and not fish from only a few families.
Copper metabolism and gut morphology in rainbow trout (Oncorhynchus mykiss) during chronic sublethal dietary copper exposure
Authors: Kamunde Collins N , Grosell Martin , Lott John NA , Wood Chris M
Published: April 2011

Juvenile rainbow trout (Oncorhynchus mykiss) were exposed to 11 (control), 300 (medium), and 1000 µg Cu·g1 (high) (as CuSO4·5H2O) in the diet for 28 days at a daily ration of 4% wet body weight, with a background waterborne Cu concentration of 3 µg·L1. There was no effect of dietary Cu on growth, condition factor, or food conversion efficiency. Whole-body Cu content increased continuously over the exposure period in all groups and was twofold and fourfold higher than controls at day 28 for the medium- and high-Cu diets, respectively. Copper accumulated mainly in liver and gut tissue, with the latter stabilizing by day 14. Accumulation also occurred in gill, kidney, and carcass. Plasma Cu concentration was not different from the controls whereas Cu in bile was greatly elevated, an indication of increased hepatobiliary excretion. Dietary Cu pre-exposure decreased the uptake of waterborne Cu across the gills, providing the first evidence of homeostatic interaction between the two routes of uptake. Electron microscopic observations of the midintestine revealed numerous mitochondria, lysosomes, lamellated bodies, and extensive lamellar processes in the enterocytes. Apoptosis, mitosis, and eosinophilic granule cells were more apparent in Cu-exposed fish.
Examining feeding strategies and position choice of drift-feeding salmonids using an individual-based, mechanistic foraging model
Authors: Guensch G R , Hardy T B , Addley R C
Published: April 2011

We demonstrated the ability of a mechanistic habitat selection model to predict habitat selection of brown trout (Salmo trutta) and mountain whitefish (Prosopium williamsoni) during summer and winter conditions in the Blacksmith Fork River, Utah. By subtracting energy costs and losses from the gross energy intake rate (GEI) obtained through simulation of prey capture, the model calculates the potential net energy intake rate (NEI) of a given stream position, which is essentially the rate of energy intake available for growth and reproduction. The prey capture model incorporates the size, swimming speed, and reaction distance of the fish; the velocity, depth, temperature, and turbidity of the water; and the density and size composition of the drifting invertebrates. The results suggest that during both summer and winter, the brown trout and mountain whitefish in our study reach avoided locations providing low NEI and preferred locations providing a high ratio of NEI to the swimming cost (SC) at the focal position of the fish (NEI/SC). This supports the idea that the drift-feeding fish in this study selected stream positions that provided adequate NEI for the least amount of swimming effort.
A catch per unit effort - soak time model for the Bristol Bay red king crab fishery, 1991-1997
Authors: Briand Geneviève , Matulich Scott C , Mittelhammer Ron C
Published: April 2011

Postseason commercial fisheries data are used to estimate a catch per unit effort (CPUE)  soak time relationship for the 19911993 and 19961997 Bristol Bay red king crab (Paralithodes camtschaticus) fishery in order to gain regulatory and in-season management insight. Use of commercial fishery data allows our model to capture the influence of biological and environmental effects as well as behavioral responses of crabbers to changing natural and regulatory conditions on CPUE. However, data deficiencies present a variety of estimation challenges, especially when the data are derived from neither a contemporaneous nor a scientifically designed sample of the fleet. A statistical framework for dealing with such challenges is illustrated in this paper. This research uncovered three major results. First, data pooling guided by recursive estimation/hypothesis testing is shown to be essential. Second, the analysis provides insight into CPUE response to changing conditions, whether biological, ecological, or policy induced. Third, it is apparent that more complete and contemporaneous collection of commercial fisheries data is critical to refine the estimation of CPUE - soak time relationships. Then, it may be possible to isolate the inter- and intra-seasonal influence of biological and environmental effects as well as behavioral responses of crabbers to changing natural and regulatory conditions.
Horizontal transport of marine organisms resulting from interactions between diel vertical migration and tidal currents off the west coast of Vancouver Island
Authors: Smith C L , Hill A E , Foreman M GG , Peña M A
Published: April 2011

This paper examines horizontal transport of marine organisms resulting from interaction between diel vertical migration (DVM) and numerically generated tidal and buoyancy currents for the southern continental shelf and slope of Vancouver Island, Canada. In particular, we hypothesise that this mechanism is partially responsible for an observed decline in zooplankton biomass on the shelf during spring and summer. We have chosen to operationally test our hypothesis by using the tidal and seasonal buoyancy flows from a three-dimensional baroclinic finite element model to investigate transport resulting from DVMtidal interactions. This is achieved by statistically comparing the distribution of passive and migrating particles. In this way, we quantitatively show that in summer, nonmigrating particles initially located on the continental shelf tend to be displaced northwestward by the Vancouver Island Coastal Current, while particles undergoing DVM exhibit off-shelf net displacement from June to September.
Spatial and temporal variability in water temperatures in the littoral zone of a multibasin lake
Authors: Finlay Kerri P , Cyr Hélène , Shuter Brian J
Published: April 2011

Current models of the offshore thermal structure in lakes suggest that the thermal regime inshore should vary seasonally, and should vary systematically from upwind to downwind littoral sites. To test these hypotheses, we measured mean temperature and short-term (<2 days) temporal variability in water temperature at 23 shallow littoral sites in four basins of Lake Opeongo, Ontario, Canada. Water temperature in the littoral zone was most variable, both spatially and temporally, in the spring. Spring water temperature differed by as much as 715°C among littoral sites in different basins (median difference among sites = 24°C). Downwind sites were generally warmer and had more constant temperature than upwind sites, but the magnitude of these differences varied among basins of different sizes and shapes. Simple calculations of growth rates and of fish hatching times suggest that the observed variability in water temperature would result in differences in the productivity of different portions of the littoral zone.
XI: THE EGGS AND EARLY LIFE-HISTORY OF THE HERRING, GASPEREAU, SHAD AND OTHER CLUPEOIDS.
Authors: PRINCE EDWARD E.
Published: April 2011

not available
Stable nitrogen isotopes as indicators of anthropogenic activities in small freshwater systems
Authors: Lake James L , McKinney Richard A , Osterman Frank A , Pruell Richard J , Kiddon John , Ryba Stephan A , Libby Alan D
Published: April 2011

Stable nitrogen isotope ratios (δ15N) were measured in fish, mussel, and sediment samples taken from 17 small freshwater sites to examine food chain length and trophic position across sites affected by differing levels of anthropogenic activity. Both shoreline development and fish species composition varied greatly among sites, and a range of up to 11.2 was found for the δ15N values of largemouth bass (Micropterus salmoides). Fish δ15N values were baseline corrected using unionid mussel (Elliptio complanata) δ15N values. Predators, such as largemouth bass and chain pickerel (Esox niger), exhibited normalized δ15N values that were less variable than those of benthic-feeding fishes. Relationships between δ15N and dissolved inorganic nitrogen concentrations indicated that δ15N was a valid descriptor of eutrophication at sites with low dissolved inorganic nitrogen concentrations. The fraction of residential land in buffer zones surrounding sites was correlated with fish δ15N, indicating that urban development, and presumably human wastewater, resulted in elevated δ15N values in these small freshwater systems.
Niche breadth in clonal and sexual fish (Poeciliopsis): a test of the frozen niche variation model
Authors: Gray Melissa M , Weeks Stephen C
Published: April 2011

The evolution and subsequent maintenance of sex has been debated for many years, and there are numerous aspects that remain poorly understood. When comparing sexual with asexual reproduction, there are many more apparent benefits to being asexual than sexual. The frozen niche variation (FNV) model describes how asexual clones can arise from a sexual population and how the two reproductive types can coexist. Herein we compared three sympatric populations of sexual and asexual fish (one sexual population, Poeciliopsis monacha, and two clonal populations, P. 2-monacha-lucida) to test the assumption of the FNV model that sexual populations have a broader dietary niche (as measured by gut contents analysis) than clonal populations. Individual sexual fish had similar dietary breadth when compared with clonal individuals. However, dietary breadth for sexual populations as a whole was broader than for either clonal population, indicating differences in between-individual dietary choice. Our results support the primary assumption of the FNV model and thereby provide a possible explanation for the maintenance of sexual reproduction in this clonalsexual complex.
What is the carrying capacity for fish in the ocean? A meta-analysis of population dynamics of North Atlantic cod
Authors: Myers Ransom A , MacKenzie Brian R , Bowen Keith G , Barrowman Nicholas J
Published: April 2011

Population and community data in one study are usually analyzed in isolation from other data. Here, we introduce statistical methods that allow many data sets to be analyzed simultaneously such that different studies may "borrow strength" from each other. In the simplest case, we simultaneously model 21 Atlanic cod (Gadus morhua) stocks in the North Atlantic assuming that the maximum reproductive rate and the carrying capacity per unit area are random variables. This method uses a nonlinear mixed model and is a natural approach to investigate how carrying capacity varies among populations. We used empirical Bayes techniques to estimate the maximum reproductive rate and carrying capacity of each stock. In all cases, the empirical Bayes estimates were biologically reasonable, whereas a stock by stock analysis occasionally yielded nonsensical parameter estimates (e.g., infinite values). Our analysis showed that the carrying capacity per unit area varied by more than 20-fold among populations and that much of this variation was related to temperature. That is, the carrying capacity per square kilometre declines as temperature increases.
Characterizing fish populations: effects of sample size and population structure on the precision of demographic parameter estimates
Authors: Kritzer J P , Davies C R , Mapstone B D
Published: April 2011

We examined precision of size, age, growth, and mortality parameters for four reef fishes at sample sizes ranging from 25 to 1000 using bootstrapped population samples. The results are illustrative rather than prescriptive in that we do not determine "optimum" sample sizes, but rather describe improvements in precision with increasing sample size. Furthermore, we do not address the related issue of accuracy. In general, a sample size needed to be tripled to halve precision at that sample size. Mean lengths and ages were most precise, reaching 10% by a sample size of 75 for all species. von Bertalanffy growth parameters were up to an order of magnitude more precise when constraints were placed upon the fitting process. Asymptotic lengths, L[Formula: see text], were up to eight times as precise as Brody growth coefficients, K. Catch curves were generally less precise than two other mortality estimators, but we cannot advocate any estimator until accuracy is addressed. We propose a general rule of collecting an average of 710 fish per age-class to estimate a variety of parameters. However, we more strongly suggest applying similar analyses for focal species and, where possible, with consideration of the application of parameters (e.g., sensitivity analyses).
Nutrient-dependent recovery of Atlantic salmon streams from a catastrophic flood
Authors: Weng Zhongyan , Mookerji Nandita , Mazumder Asit
Published: April 2011

The impact of a major flood and recovery of the stream communities under contrasting nutrient conditions were studied in two second-order streams of Sainte-Marguerite River, Quebec. A massive flood during the summer of 1996 caused extensive displacement of the stream substratum and severe reductions in the abundance of all biota: periphyton, benthic invertebrates, juvenile Atlantic salmon (Salmo salar), and brook trout (Salvelinus fontinalis) (especially in the 0+ age-class). In the postflood recovery phase, nutrient-enriched sections recovered significantly more rapidly than the nonenriched sections. After 1 month, periphyton biomass in the enriched sections had increased to five times that of the preflood levels, and after 2 months, the invertebrate communities had recovered to preflood levels. Fish densities and growth rates also returned to normal levels more rapidly in the enriched sections. Our results suggest that nutrient-rich systems are more resilient to massive disturbances, and so, nutrient enrichment may represent a viable tool for restoring nutrient-limited systems.
Diet of Mysis relicta in Lake Ontario as revealed by stable isotope and gut content analysis
Authors: Johannsson Ora E , Leggett Mike F , Rudstam Lars G , Servos Mark R , Mohammadian M Ali , Gal Gideon , Dermott Ron M , Hesslein Ray H
Published: April 2011

Stable isotope analysis of the potential prey and predator can be combined with gut content analysis to quantify the diet. This dietary knowledge allows the quantitative assessment of the role of key species in energy and contaminant transfer, their impact on prey communities, and their susceptibility to perturbation. The diet of Mysis relicta was examined in Lake Ontario in spring, summer, and autumn using both techniques. Mysids fed on the bottom during the day and in the pelagia and on the bottom at night. A trophic fractionation of 2.2 N between mysids and their prey provided the best correspondence between the observed stable isotope signature of mysids and that estimated from their diet. Tissue turnover rate of δ13C was slow compared with that of δ15N. Diatoms formed 50% of the assimilated diet in May. In September, 25% of large mysids feeding on the bottom contained amphipod parts and 20% contained phytoplankton. The remainder of the diet consisted of zooplankton and rotifers. The contribution of amphipods and phytoplankton could not be quantified. Revised daily consumption estimates, based on this new diet information and clearance rate estimates of consumption, gave daily consumption estimates similar to those estimated from previous bioenergetic modelling.
Fish-mediated nutrient recycling and the trophic cascade in lakes
Authors: Attayde José Luiz , Hansson Lars-Anders
Published: April 2011

The effects of planktivorous fish on phytoplankton through nutrient recycling and zooplankton herbivory were experimentally separated and their relative importance quantified in a eutrophic humic lake. Natural phytoplankton assemblages were incubated in nutrient-permeable chambers placed inside enclosures with or without fish. Outside these chambers, phytoplankton were exposed to zooplankton herbivory and to nutrient recycling by fish and zooplankton, whereas inside the chambers, phytoplankton were exposed only to nutrient recycling by these consumers. Our results show that fish had significant positive effects on cyanobacteria, cryptomonads, and chlorophytes inside the chambers, indicating that fish-mediated nutrient recycling had significant effects on these phytoplankton groups. However, our results also indicate that changes in zooplankton grazing induced by fish were an important mechanism by which fish affected all phytoplankton groups except cyanobacteria. Comparison of effect sizes revealed that the effects on cyanobacteria and chlorophytes through nutrient recycling were stronger than those through zooplankton grazing. Moreover, most of the fish-mediated nutrient recycling effects were due to increased nutrient recycling by zooplankton rather than direct nutrient excretion by fish. In conclusion, we provide experimental evidence supporting the hypothesis that fish-mediated nutrient recycling is an important mechanism affecting phytoplankton community structure and favoring cyanobacteria dominance in lakes.
Detecting environmental regimes in fish stock-recruitment relationships by fuzzy logic
Authors: Chen D G
Published: April 2011

A fuzzy logic approach is developed to model and test the impact of environmental regimes on fish stockrecruitment relationships. Traditional methods use environmental variables to classify stockrecruitment data into different membership percentiles followed by fitting the stockrecruitment models for each subset. In contrast, the fuzzy logic approach uses a continuous membership function to provide a rational basis for the classification. Thus, parameter estimation is based on a more logically consistent foundation without resorting to subjective partitions. This new approach is applied to herring stock from the west coast of Vancouver Island (Clupea harengus pallasi) using sea surface temperature as the environmental variable and to Pacific halibut stock (Hippoglossus stenolepis) using the Pacific Decadal Oscillation as the environmental variable. From these applications, the herring stockrecruitment relationships were found to vary significantly during different regimes, whereas this was not the case for halibut. However, in both instances, the fuzzy logic approach demonstrated that density-dependent effects differed between regimes. The fuzzy logic model consistently outperformed traditional approaches as measured by several diagnostic criteria. Because fuzzy logic models address uncertainty better than traditional approaches, they have the potential to improve our ability to understand factors influencing stockrecruitment relationships and thereby manage fisheries more effectively.
Estimating natural and fishing mortality and tag reporting rate of southern rock lobster (Jasus edwardsii) from a multiyear tagging model
Authors: Frusher S D , Hoenig J M
Published: April 2011

Fishing and natural mortality rates and tag reporting rate for rock lobsters (Jasus edwardsii) in northwest Tasmania, Australia, were estimated using multiyear tagging models. These estimates are necessary for assessment of the resource. Several models were examined that had either two or three tagging events each year, and either combined sexes or kept sexes separate. The model that best described the dynamics of the fishery utilized three tagging events within a year. The year was divided into discrete periods and, within each year, fishing effort and duration of period were used to apportion fishing and natural mortalities, respectively, to the periods. The separation of fishing mortalities by sex was not found to improve the models. Although high (1.01.2·year1), the instantaneous fishing mortality estimates were comparable to estimates obtained from other methods and the relative standard errors were low. Reporting rate estimates were also precise and indicated a lack of participation by the fishing industry. Estimates of natural mortality were low (0.000.02·year1) but imprecise.
Ecological hypotheses for a historical reconstruction of upper trophic level biomass in the Baltic Sea and Skagerrak
Authors: MacKenzie Brian R , Alheit Jürgen , Conley Daniel J , Holm Poul , Kinze Carl Christian
Published: April 2011

Fish and marine mammal populations in the Baltic Sea and Skagerrak have undergone major fluctuations over the past five centuries. We summarize how these fluctuations may have depended on various forms of predation (e.g., cannibalism, fishing, hunting) and environmental processes. The best-documented long-term fisheries in this region are the herring (Clupea harengus) fisheries near Bohuslän, western Sweden, and in the Øresund. These fisheries have been important since at least the 1200s and appear to be partly climatically driven. However, in the rest of the Baltic, information about fisheries for herring and other fish species is rare until after 1900. During the 20th century, while the Baltic underwent eutrophication, the biomass and landings of three fish species (cod (Gadus morhua), herring, and sprat (Sprattus sprattus)) all increased, whereas the biomass of marine mammals (grey seals (Halichoerus grypus), ringed seals (Phoca hispida), harbour porpoises (Phocoena phocoena)) decreased. The relative roles of exploitation, marine mammal predation, and environmental variability (e.g., eutrophication, major inflows of saline water, climate change) on the long-term dynamics of key fish species is not clear and requires increased collaboration among historians, fisheries and marine mammal ecologists, oceanographers, and climatologists.
II.: FISHERY BAIT EXPERIMENTS.: A PRELIMINARY REPORT UPON THE COMPARATIVE MERITS OF DIFFERENT KINDS OF BAIT USED IN COD FISHING ALONG GASPE PENINSULA.
Authors: Knight M.A., M.D. A. P.
Published: April 2011

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VI.: ON THE FAUNA OF THE ATLANTIC COAST OF CANADA.: FOURTH REPORT.
Authors: Stafford M.A., Ph. D. J.
Published: April 2011

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INVESTIGATION INTO THE PACIFIC HALIBUT FISHERIES, BRITISH COLUMBIA.
Authors: Willey D.Sc., F.R.S., F.R. Arthur
Published: April 2011

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II.: NOTES ON THE EGG AND LARVAL STAGES OF THE HALIBUT.
Authors: Prince LL.D., D.Sc., F.R. Edward E.
Published: April 2011

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THE WINTER PLANKTON IN THE NEIGHBOURHOOD OF ST. ANDREWS, 1914-15.
Authors: McMurrich M.A., Ph.D. J. Playfair
Published: April 2011

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DIATOMS AND LOBSTER REARING.
Authors: MacClement M.A., D.Sc. Prof. W. T.
Published: April 2011

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THE MARINE ALGÆ OF THE PASSAMAQUODDY REGION, NEW BRUNSWICK.
Authors: Klugh M.A. A. B.
Published: April 2011

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IV: NOTES ON THE HABITS AND DISTRIBUTION OF TEREDO NAVALIS ON THE ATLANTIC COAST OF CANADA.
Authors: Kindle Ph. D. E. M.
Published: April 2011

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XI.: SOME OBSERVATIONS ON HADDOCKS AND "FINNAN HADDIES" RELATING TO THE BACTERIOLOGY OF CURED FISH.
Authors: Harrison D.Sc. F. C.
Published: April 2011

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XIV: BATHYMETRIC CHECK LIST OF THE MARINE INVERTEBRATES OF EASTERN CANADA WITH AN INDEX TO WHITEAVES' CATALOGUE.
Authors: Kindle E. M. , Whittaker E. J.
Published: April 2011

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XVI.: HYDROIDS OF EASTERN CANADA.
Authors: Fraser Ph.D. C. McLean
Published: April 2011

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X.: Canned Sardines.—The cause of "Swells" or "Blown Cans."
Authors: Sadler M.Sc. Wilfrid
Published: April 2011

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