Estimating larval fish growth under size-dependent mortality: a numerical analysis of bias

2007 ◽  
Vol 64 (3) ◽  
pp. 554-562 ◽  
Author(s):  
Tian Tian ◽  
Øyvind Fiksen ◽  
Arild Folkvord
Keyword(s):  
Growth Rate ◽  
Longitudinal Data ◽  
Growth Rates ◽  
Mortality Rates ◽  
Growth Patterns ◽  
Cross Sectional ◽  
Larval Phase ◽  
Size Dependent ◽  
Recruitment Success ◽  
Dependent Mortality

The early larval phase is characterized by high growth and mortality rates. Estimates of growth from both population (cross-sectional) and individual (longitudinal) data may be biased when mortality is size-dependent. Here, we use a simple individual-based model to assess the range of bias in estimates of growth under various size-dependent patterns of growth and mortality rates. A series of simulations indicate that size distribution of individuals in the population may contribute significantly to bias in growth estimates, but that typical size-dependent growth patterns have minor effects. Growth rate estimates from longitudinal data (otolith readings) are closer to true values than estimates from cross-sectional data (population growth rates). The latter may produce bias in growth estimation of about 0.03 day–1 (in instantaneous, specific growth rate) or >40% difference in some situations. Four potential patterns of size-dependent mortality are tested and analyzed for their impact on growth estimates. The bias is shown to yield large differences in estimated cohort survival rates. High autocorrelation and variance in growth rates tend to increase growth estimates and bias, as well as recruitment success. We also found that autocorrelated growth patterns, reflecting environmental variance structure, had strong impact on recruitment success of a cohort.

An Appraisal of the Size-Dependent Mortality Hypothesis for Larval Fish: Comparison of a Multispecies Study with an Empirical Review

1993 ◽  
Vol 50 (10) ◽  
pp. 2166-2174 ◽  
Author(s):  
Pierre Pepin
Keyword(s):  
Growth Rate ◽  
Larval Fish ◽  
Mortality Rates ◽  
Accurate Information ◽  
Constant Growth Rate ◽  
Size Dependent ◽  
Conception Bay ◽  
Biased Estimates ◽  
Constant Growth ◽  
Dependent Mortality

This study presents an assessment of the size-dependent mortality hypothesis for larval fish from a multispecies survey of Conception Bay, Newfoundland, Canada. Mortality rates are estimated using a length-based method (per millimetre). The results from this survey are consistent with previous studies which indicate that losses decrease with increasing size of fish. However, for each species within this survey, mortality rates are constant. Comparison of mortality rates within species among surveys indicates that as the range of size categories sampled increases, the estimated mortality rates decrease, despite evidence of adequate fit to the length-based model. The findings indicate that previous relationships between size or stage and mortality of larval fish should be reevaluated. Length-based methodology used to estimate mortality rates of larval fish appears to provide biased estimates of this vital characteristic. It is suggested that using size as a proxy for biological age (i.e., assuming a constant growth rate) may be an invalid assumption. Future surveys will need to provide accurate information about the age structure of larvae sampled in order to properly estimate mortality rates.

Single Crystal Silicon Carbide On Silicon Using A Supersonic Gas Jet Of Methylsilane

1997 ◽  
Vol 483 ◽  
Author(s):  
S. A. Ustin ◽  
C. Long ◽  
L. Lauhon ◽  
W. Ho
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Single Crystal Silicon ◽  
Maximum Growth ◽  
X Ray Diffraction ◽  
Crystal Silicon ◽  
Cross Sectional ◽  
Supersonic Molecular Beam ◽  
Transmission Electron

AbstractCubic SiC films have been grown on Si(001) and Si(111) substrates at temperatures between 600 °C and 900 °C with a single supersonic molecular beam source. Methylsilane (H3SiCH3) was used as the sole precursor with hydrogen and nitrogen as seeding gases. Optical reflectance was used to monitor in situ growth rate and macroscopic roughness. The growth rate of SiC was found to depend strongly on substrate orientation, methylsilane kinetic energy, and growth temperature. Growth rates were 1.5 to 2 times greater on Si(111) than on Si(001). The maximum growth rates achieved were 0.63 μm/hr on Si(111) and 0.375μm/hr on Si(001). Transmission electron diffraction (TED) and x-ray diffraction (XRD) were used for structural characterization. In-plane azimuthal (ø-) scans show that films on Si(001) have the correct 4-fold symmetry and that films on Si(111) have a 6-fold symmetry. The 6-fold symmetry indicates that stacking has occurred in two different sequences and double positioning boundaries have been formed. The minimum rocking curve width for SiC on Si(001) and Si(111) is 1.2°. Fourier Transform Infrared (FTIR) absorption was performed to discern the chemical bonding. Cross Sectional Transmission Electron Microscopy (XTEM) was used to image the SiC/Si interface.

Abstract 13513: Serial CT Surveillance of Abdominal Aortic Aneurysm Diameter Demonstrates Predominantly Linear Growth (N-TA 3 CT)

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Sydney Olson ◽  
Marniker Wijesinha ◽  
Annalise Panthofer ◽  
William Blackwelder ◽  
Gilbert R Upchurch ◽  
...  
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Linear Growth ◽  
Growth Patterns ◽  
Aortic Aneurysms ◽  
Transverse Diameter ◽  
Invasive Treatment ◽  
Abdominal Aortic ◽  
Risk Of Rupture ◽  
Serial Ct

Objective: Small abdominal aortic aneurysms (AAAs) have a low risk of rupture. Intervention is indicated when diameters exceed established thresholds. This study assessed the growth rates and patterns of AAAs over 2 years as documented on serial CT scans from the Non-Invasive Treatment of AAA Clinical Trial. Methods: 254 patients, 35 females with baseline AAA maximum transverse diameter (MTD) between 3.5-4.5 cm and 219 males with baseline MTD 3.5-5.0 cm, were included in this study. Linear regressions and segmental growth rates were used to model growth rates and patterns. Results: The yearly growth rates of AAA MTDs had a median of 0.17 cm/yr and mean of 0.19 cm/yr ± 0.14 (Figure 1). 10% of AAA displayed minimal to no growth (< 0.05 cm/yr), 62% low growth (0.05-0.25 cm/yr), 28% high growth (> 0.25 cm/yr). Baseline AAA diameter accounted for only 5.4% of growth rate variance (P<0.001, R 2 0.05). Most AAAs displayed linear growth (70%); large variations in interval growth rates occurred infrequently (3% staccato growth, 4% exponential growth); a minority of subjects’ growth patterns were not clearly classifiable (11% indeterminate-not growing, 12% indeterminate-growing) (Figure 2). No patients with baseline MTD < 4.25 cm exceeded sex-specific repair thresholds (males 0 / 92, [95% CI, 0.00-0.06]; females 0 / 25 [95% CI, 0.00-0.25]) in the course of follow-up for as long as two years. Conclusions: The majority of small AAAs exhibit linear growth; large intra-patient growth rate variations were infrequently observed over 2 years. AAA < 4.25 cm can be followed with a CT scan in 2 years with little chance of exceeding interventional MTD thresholds of 5.5 cm for men.

In situ growth rate estimates of Southern Ocean krill, Thysanoessa macrura

2019 ◽  
Vol 31 (3) ◽  
pp. 116-122 ◽  
Author(s):  
Jake R. Wallis ◽  
Jessica E. Melvin ◽  
Robert King ◽  
So Kawaguchi
Keyword(s):  
Growth Rate ◽  
Southern Ocean ◽  
Growth Rates ◽  
Somatic Growth ◽  
Growth Patterns ◽  
Daily Growth ◽  
Thysanoessa Macrura ◽  
Growth Method ◽  
Repeated Sampling ◽  
The Antarctic

AbstractGrowth, which is intrinsically linked to environmental conditions including temperature and food availability are highly variable both temporally and spatially. Estimates of growth rates of the Southern Ocean euphausiid Thysanoessa macrura are currently restricted to limited studies which rely upon repeated sampling and length-frequency analysis to quantify growth rates. The instantaneous growth method (IGR) was used to measure the growth rate of T. macrura successfully in the southern Kerulen Plateau region during summer, providing the first IGR parameters for the Southern Ocean euphausiid species. Results of the four-day IGR incubation indicate a period of low somatic growth for adult T. macrura. Males had a longer intermoult period (IMP) (62 days) than females (42 days), but the sexes exhibited similar daily growth rates of 0.011 mm day−1 and 0.012 mm day−1 respectively. Juveniles exhibited the fastest growth, with an IMP of 13 days and daily growth rate of 0.055 mm day−1 indicating a prolonged growth season, similar to the Antarctic krill E. superba. Consequently, we highlight the usability of the IGR method and strongly encourage its use in developing a comprehensive understanding of spatial and seasonal growth patterns of T. macrura.

scholarly journals Radial Growth Patterns Associated with Tree Mortality in Nothofagus pumilio Forest

Forests ◽  
2019 ◽  
Vol 10 (6) ◽  
pp. 489 ◽  
Author(s):  
Milagros Rodríguez-Catón ◽  
Ricardo Villalba ◽  
Ana Srur ◽  
A. Park Williams
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Forest Dynamics ◽  
Radial Growth ◽  
Tree Mortality ◽  
Growth Patterns ◽  
Severe Drought ◽  
Nothofagus Pumilio ◽  
Total Size ◽  
Growth Trends

Tree mortality is a key process in forest dynamics. Despite decades of effort to understand this process, many uncertainties remain. South American broadleaf species are particularly under-represented in global studies on mortality and forest dynamics. We sampled monospecific broadleaf Nothofagus pumilio forests in northern Patagonia to predict tree mortality based on stem growth. Live or dead conditions in N. pumilio trees can be predicted with high accuracy using growth rate as an explanatory variable in logistic models. In Paso Córdova (CO), Argentina, where the models were calibrated, the probability of death was a strong negative function of radial growth, particularly during the six years prior to death. In addition, negative growth trends during 30 to 45 years prior to death increased the accuracy of the models. The CO site was affected by an extreme drought during the summer 1978–1979, triggering negative trends in radial growth of many trees. Individuals showing below-average and persistent negative trends in radial growth are more likely to die than those showing high growth rates and positive growth trends in recent decades, indicating the key role of droughts in inducing mortality. The models calibrated at the CO site showed high verification skill by accurately predicting tree mortality at two independent sites 76 and 141 km away. Models based on relative growth rates showed the highest and most balanced accuracy for both live and dead individuals. Thus, the death of individuals across different N. pumilio sites was largely determined by the growth rate relative to the total size of the individuals. Our findings highlight episodic severe drought as a triggering mechanism for growth decline and eventual death for N. pumilio, similar to results found previously for several other species around the globe. In the coming decades, many forests globally will be exposed to more frequent and/or severe episodes of reduced warm-season soil moisture. Tree-ring studies such as this one can aid prediction of future changes in forest productivity, mortality, and composition.

Ecological Traits of the Eucalyptus L'hérit Subgenera Monocalyptus and Symphyomyrtus

1989 ◽  
Vol 37 (3) ◽  
pp. 207 ◽  
Author(s):  
IR Noble
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Root Morphology ◽  
Related Species ◽  
Early Growth ◽  
Growth Patterns ◽  
Leaf Chemistry ◽  
Ecological Traits ◽  
Closely Related Species ◽  
Genus Eucalyptus

The genus Eucalyptus L'Hérit. dominates most of the forests and woodlands of Australia. Many stands consist of intimate mixtures of species from different subgenera. The ecological traits of the two largest subgenera, Symphyomyrtus and Monocalyptus, are reviewed. Consistent differences in herbivore and parasite damage to leaves; in water relations; in tolerance to waterlogging, flooding, salinity and frost; in nutrient usage; in response to Phytophthora cinnamorni; and in early growth patterns are described. These can be summarised as differences in leaf chemistry; in root morphology, chemistry and activity; and in early growth rates. It is suggested that the differences in the ecological traits, and especially in the early growth rate, may help explain the coexistence of closely related species of similar habits in eucalypt communities.

scholarly journals Growth Rate Variation and Larval Survival: Inferences from an Individual-Based Size-Dependent Predation Model

1993 ◽  
Vol 50 (1) ◽  
pp. 133-142 ◽  
Author(s):  
James A. Rice ◽  
Thomas J. Miller ◽  
Kenneth A. Rose ◽  
Larry B. Crowder ◽  
Elizabeth A. Marschall ◽  
...  
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Individual Variability ◽  
Individual Growth ◽  
Rate Variation ◽  
High Survival ◽  
Initial Growth ◽  
Size Dependent ◽  
The Mean ◽  
Selection For

We used an individual-based Monte Carlo simulation model to explore how changes in the mean and variance of growth rates of individuals in a larval fish cohort interact with size-dependent predation to affect the number and characteristics of individual survivors. Small changes in initial cohort mean growth rate can change survival over the first 60 d of life 10-to 30-fold. But when variance in growth rate among individuals is high, survival can be substantially higher than expected from the initial mean cohort growth rate. Selection for faster-growing individuals becomes stronger with increasing variance and increasing predation rate. In some cases, > 80% of the survivors may come from the upper 25% of the initial growth rate distribution, and the mean growth rate of the survivors may exceed twice the initial mean growth rate. When individual growth rates change from day to day rather than remaining constant, the contribution of atypical individuals is accentuated even further. Counterintuitively, most of the selection for faster-growing individuals happens only after the majority of mortality has already taken place. These results suggest that interactions between individual variability and selective mortality may have important cohort-level implications for survival in fishes.

Estimation of Size Selectivity and Movement Rates from Mark–Recovery Data

1994 ◽  
Vol 51 (3) ◽  
pp. 734-742 ◽  
Author(s):  
Alejandro Anganuzzi ◽  
Ray Hilborn ◽  
John R. Skalski
Keyword(s):  
Mortality Rates ◽  
Fishing Mortality ◽  
Size Selectivity ◽  
Movement Rates ◽  
Return Rates ◽  
Size Dependent ◽  
Pacific Halibut ◽  
Hippoglossus Stenolepis ◽  
Time Specific ◽  
Dependent Mortality

Size selectivity, movement rates among spatial strata, and size-dependent mortality rates were estimated from mark–recovery data of Pacific halibut (Hippoglossus stenolepis). Growth rates, area- and time-specific fishing mortality on fully vulnerable individuals, and tag return rates were assumed known from other data. We obtained similar estimates from a model that considered movement to take place immediately after tagging and a model that assumed that movement takes place once each year. The inability to distinguish between one-time and annual movement is most likely due to the fact that tagged juveniles were not recovered until 3–5 yr later when they became vulnerable to the adult fishery.

Growth ecology of the tree lizard Urosaurus bicarinatus (Squamata: Phrynosomatidae), in a tropical dry forest of the Chamela Region, Mexico

2016 ◽  
Vol 66 (2) ◽  
pp. 189-199 ◽  
Author(s):  
Aurelio Ramírez-Bautista ◽  
Uriel Hernández-Salinas ◽  
J. Gastón Zamora-Abrego
Keyword(s):  
Growth Rate ◽  
Life History ◽  
Growth Rates ◽  
Average Rate ◽  
Growth Patterns ◽  
Dry Forest ◽  
Von Bertalanffy ◽  
Mexican Pacific ◽  
Males And Females ◽  
Tree Lizard

Determination of growth rate provides an important component of an organism’s life history, making estimations of size at maturity, survival rate, and longevity possible. Here, we report on growth rate of males and females of the tropical tree lizard Urosaurus bicarinatus, in a seasonal environment in the state of Jalisco on the Mexican Pacific Coast. We calculated body growth rates and fitted these to the Von Bertalanffy, the logistic-by-length, and the logistic-by-weight growth models. The Von Bertalanffy model provided the best fit, and we used it to analyze the growth pattern. Males and females did not differ in estimated asymptotic size and other characteristic growth parameters. Estimated growth curve predicted an age at maturity of 38 mm SVL on 120 days for males, and 40 mm SVL on 170 days for females. On the basis of the similarities in the growth rates between the sexes, comparisons were made between seasons, and we found that the average rate of growth was slightly, albeit insignificantly, higher in the rainy season than in the dry season. The similarities in the growth patterns for the sexes of this species might be indicative of variance in its life history traits (e.g., fecundity, egg size) compared to those of other populations of this species and other species of this genus; therefore, it is important to document interpopulation differences to understand the evolutionary changes that have led to optimal adaptation in a particular environment more accurately.

The Determinants of Idiosyncratic Volatility

2017 ◽  
Vol 25 (4) ◽  
pp. 509-545
Author(s):  
Jaeuk Khil ◽  
Song Hee Kim ◽  
Eun Jung Lee
Keyword(s):  
Growth Rate ◽  
Time Series ◽  
Cross Section ◽  
Growth Rates ◽  
Idiosyncratic Volatility ◽  
Return Volatility ◽  
Firm Level ◽  
Cross Sectional ◽  
Asset Growth ◽  
The Cross

We investigate the cross-sectional and time-series determinants of idiosyncratic volatility in the Korean market. In particular, we focus on the empirical relation between firms’ asset growth rate and idiosyncratic stock return volatility. We find that, in the cross-section, companies with high idiosyncratic volatility tend to be small and highly leveraged, have high variance of ROE and Market to Book ratio, high turnover rate, and pay no dividends. Furthermore, firms with extreme (either high positive or negative) asset growth rates have high idiosyncratic return volatility than firms with moderate growth rates, suggesting the V-shaped relation between asset growth rate and idiosyncratic return volatility. We find that the V-shaped relation is robust even after controlling for other factors. In time-series, we find that firm-level idiosyncratic volatility is positively related to the dispersion of the cross-sectional asset growth rates. As a result, this study is contributed to show that the asset growth is the most important predictor of firm-level idiosyncratic return volatility in both the cross-section and the time-series in the Korean stock market. In addition, we show how the effect of risk factors varies with industries.

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