Effects of intrapopulation variability on von Bertalanffy growth parameter estimates from equal mark-recapture intervals

1997 ◽  
Vol 54 (9) ◽  
pp. 2025-2032 ◽  
Author(s):  
E.B. Smith ◽  
F.M. Williams ◽  
C.R. Fisher
1997 ◽  
Vol 54 (9) ◽  
pp. 2025-2032
Author(s):  
E B Smith ◽  
F M Williams ◽  
C R Fisher

The effects of intrapopulation variability on the parameter estimates of the von Bertalanffy growth equation have received discussion in the literature. Here we evaluated the effects of intrapopulation variability, using computer simulations, on four commonly used methods for estimating the von Bertalanffy growth parameters: the Ford-Walford plot, Ricker's method, Bayley's method, and Fabens' method. Intrapopulation variability in growth rates (k) and maximum sizes ( L infinity ) plus initial size distributions and measurement error, were tested for their effects on the accuracy of the parameter estimates using simulated mark-recapture data with equal recapture intervals. Fabens' method and a modified Ford-Walford plot provided the most accurate estimates in all cases, but when intrapopulation variability was large, they performed poorly. With moderate intrapopulation variability, the bias in estimates was small although between-sample variance was quite large. Biased initial size distributions without either small or large size classes cause a magnification of the estimation errors. Without knowledge of the degree of intrapopulation variability in a natural population, large errors of unknown magnitude in parameter estimation can result, and care should be taken when interpreting these estimates. However, if this variability can be quantified, then approximate parameter estimate errors can be obtained.


2022 ◽  
Vol 8 ◽  
Author(s):  
Shui-Kai Chang ◽  
Tzu-Lun Yuan ◽  
Simon D. Hoyle ◽  
Jessica H. Farley ◽  
Jen-Chieh Shiao

Growth shapes the life history of fishes. Establishing appropriate aging procedures and selecting representative growth models are important steps in developing stock assessments. Flyingfishes (Exocoetidae) have ecological, economic, and cultural importance to many coastal countries including Taiwan. There are 29 species of flyingfishes found in the Kuroshio Current off Taiwan and adjacent waters, comprising 56% of the flyingfishes taxa recorded worldwide. Among the six dominant species in Taiwan, four are of special importance. This study reviews aging data of these four species, documents major points of the aging methods to address three aging issues identified in the literature, and applies multi-model inference to estimate sex-combined and sex-specific growth parameters for each species. The candidate growth models examined included von Bertalanffy, Gompertz, Logistic, and Richards models, and the resulting optimal model tended to be the von Bertalanffy model for sex-combined data and Gompertz and von Bertalanffy models for sex-specific cases. The study also estimates hatch dates from size data collected from 2008 to 2017; the results suggest that the four flyingfishes have two spawning seasons per year. Length-weight relationships are also estimated for each species. Finally, the study combines the optimal growth estimates from this study with estimates for all flyingfishes published globally, and statistically classifies the estimates into clusters by hierarchical clustering analysis of logged growth parameters. The results demonstrate that aging materials substantially affect growth parameter estimates. This is the first study to estimate growth parameters of flyingfishes with multiple model consideration. This study provides advice for aging flyingfishes based on the three aging issues and the classification analysis, including a recommendation of using the asterisci for aging flyingfishes to avoid complex otolith processing procedures, which could help researchers from coastal countries to obtain accurate growth parameters for many flyingfishes.


<em>Abstract</em>.—Accurate estimates of growth and mortality are important for management of recreational fisheries. Accurate age estimates often require the sacrifice of fish; thus, assessments of growth and mortality rates of trophy fishes such as Muskellunge <em>Esox masquinongy </em>often lack sufficient data. Mark–recapture history can be used as a nonlethal alternative to estimate growth and mortality in fishes. To determine the utility of this approach, we used data from a 17-year Muskellunge mark–recapture program conducted on two Illinois reservoirs (Kinkaid Lake and North Spring Lake). Von Bertalanffy parameter estimates by sex, lake, and tag type (passive integrated transponder and T-bar anchor tags) were obtained using a novel modification of the Fabens growth model and compared to von Bertalanffy growth estimates using known- or scale-aged fish. Mortality was calculated using both age- and length-based methods. Fabens growth model estimates of asymptotic length (<em>L</em><sub>∞</sub>) and growth coefficient (<EM>K</EM>) were within 6% (≤62 mm) and 23% (≤0.11) of corresponding von Bertalanffy growth model parameter estimates from known- or scale-aged fish by lake and sex. Provided that all sizes of fish are sampled, 4 years of mark–recapture data with more than 100 recaptures were found to be sufficient to produce reliable parameter estimates. Growth parameters differed between male fish tagged with passive integrated transponder or T-bar anchor tags but did not differ by tag type for females. Differences in Muskellunge growth and mortality rates between the two study lakes suggest that changing from a regionally applied minimum length limit to lake-specific minimum length limits may be warranted. Our results highlight the feasibility of mark–recapture data as a nonlethal technique to estimate population-specific growth and mortality rates for Muskellunge and the potential value of this approach in facilitating lake-specific Muskellunge management.


2021 ◽  
Vol 657 ◽  
pp. 191-207
Author(s):  
MD Ramirez ◽  
T Popovska ◽  
EA Babcock

Knowledge of sea turtle demographic rates is central to modeling their population dynamics, but few studies have quantitatively synthesized existing data globally. Here, we used a Bayesian hierarchical model to conduct a meta-analysis of published von Bertalanffy growth curve parameters (growth coefficient, K; asymptotic length, L∞) for chelonid sea turtles. We identified 34 studies for 5 of 6 extant chelonids that met minimum selection criteria. We implemented a suite of models that included a multivariate normal likelihood on the log-transformed values of the 2 parameters to evaluate the influence of species, population (regional management unit, RMU), parameter estimation method (mark-recapture, skeletochronology, length-frequency analysis), latitude, and sampled body size range (all sizes, no large, no small, no large or small) on growth parameter estimates. According to information criteria, the best model included a random effect of species. The second best model also included latitude as a fixed effect, but RMU, parameter estimation method, latitude, and sampled body size ultimately did not strongly influence the means or variances of K and L∞ among studies. The apparent lack of RMU effect on parameter estimates within species may be an artifact of the small number of RMUs with published growth parameter estimates. The species-specific, and in some cases RMU-specific, posterior means and standard deviations of K and L∞ from this study would be appropriate priors for future studies of growth in chelonid sea turtles or for models of population dynamics. We highlight the need for expanded study and synthesis of sea turtle somatic growth rates.


1992 ◽  
Vol 43 (5) ◽  
pp. 1229 ◽  
Author(s):  
K.R. Rowling ◽  
DD Reid

Estimates of von Bertalanffy growth parameters were made for mature (>3-year-old) gemfish (Rexea solandri), using otoliths sampled biennially from commercial catches between 1980 and 1986. During this period, there was a significant decline in the mean length of mature gemfish in the catch. Large variations in growth-parameter estimates were found over the period sampled (e.g. L∞ ranged between 87.3 and 130.3 cm for males and between 113.1 and 134.7 cm for females). Likelihood-ratio tests showed many of the growth-parameter estimates to be significantly different between the years sampled. Inclusion in the analyses of data for juvenile (1- to 3-year-old) fish considerably reduced both the standard errors of the parameter estimates and the significance of the variations between them. Comparison of parameters estimated by following the growth of individual cohorts spawned in 1975 and 1981 suggested that the variations in the parameters for the 1980-86 data were caused by differences in the length composition of the samples rather than by changes in the growth rate of the fish. The results suggest the need for care when comparing growth parameters estimated for different populations, especially when there are large differences in length composition. The best estimates of growth parameters for gemfish were considered to be those derived from the aggregate data for the whole of the period sampled, including the data for juveniles. For male gemfish these best estimates (with asymptotic standard errors in parentheses) were L∞ =97.5 (0.8) cm, K=0.212 (0.005) year-1 and to = - 0.54 (0.05) years, and for females the estimates were L∞ = 109.4 (0.6) cm, K= 0.180 (0.003) year-1 and to= -0.63 (0.04) years. Likelihood-ratio tests showed these estimates of L∞ and K to be significantly different between the sexes.


2017 ◽  
Vol 4 (2) ◽  
pp. 316
Author(s):  
Nafi Sakila ◽  
Dinda Ayu Ramadhani ◽  
Ani Suryanti

Sei Nipah has enormous potential for natural resources. Natural resources that serve as the main livelihood in fulfilling daily needs in Kampung Nipah is shellfish. Shellfish (M. meretrix) is one of the shells that many interested by the surrounding community. The purpose of this research is to know growth parameter and age group of shellfish (M. meretrix) in Kampung Nipah. The sampling technique was done randomly (simple random sampling). Sampling time is done at low tide. Sampling was conducted in March - May 2017. The results showed differences in the length of different shells each month. The size group of shellfish (M. meretrix) found only one size group during the three months of the study. Analysis of shellfish growth parameters based on data of long frequency distribution showed length of infiniti (L?) 33,10 mm and growth growth (K) that was 1,21 per month. Von Bertalanffy Growth Parameters Lt = 33.1 (1-e [-1.21 (t + 0.12)]) Long infiniti size is seen the growth of shellfish shells can no longer be worked Shells reach maximum length at the age of 13 months with a shell length of 33.10 mm.The youthful shells have rapid growth and as age increases, when it reaches old age the rate of growth will slow even.


1992 ◽  
Vol 49 (4) ◽  
pp. 632-643 ◽  
Author(s):  
T. J. Mulligan ◽  
B. M. Leaman

Observations at a single point in time of length-at-age (LAA) for a long-lived rockfish (Sebastes alutus) show that old fish are shorter than intermediate-aged fish. Fitting of a von Bertalanffy growth model to these data produces a systematic trend in the residual of observed versus calculated LAA. We examined how such LAA data can lead to erroneous conclusions about individual growth, and whether asymptotic growth can give rise to such data. We considered two hypotheses: (i) that a time trend in growth rate resulted in larger fish in more recent years and (ii) that there are multiple growth types, where growth and mortality rates are directly related. Using a general growth model that incorporated both (i) and (ii), we show that both hypotheses can generate data identical to those for the rockfish. A single set of LAA data is inadequate for describing individual growth; however, if sufficient data are available, model ambiguity can be resolved and reasonable parameter estimates obtained. Analysis of the rockfish data indicates that (ii) is more likely to explain the observations than (i). We show how fisheries on such species may preclude our understanding these biological relationships.


Author(s):  
Ivelina Yordanova Zlateva ◽  
Nikola Nikolov

Advanced in the present article is a Two-step procedure designed on the methods of the least squares (LS) and instrumental variable (IV) techniques for simultaneous estimation of the three unknown parameters L∞, K and t0, which represent the individual growth of fish in the von Bertalanffy growth equation. For the purposes of the present analysis, specific MATLAB-based software has been developed through simulated data sets to test the operational workability of the proposed procedure and pinpoint areas of improvement. The resulting parameter estimates have been analyzed on the basis of consecutive comparison (the initial conditions being the same) between the results delivered by the two-step procedure for simultaneous estimation of L∞, K and t0 and the results obtained via the most commonly employed methods for estimating growth parameters; first, use has been made of the Gulland-and-Holt method for estimating the asymptotic length L∞and the curvature parameter K, followed by the von Bertalanffy method for estimation of t0.


2004 ◽  
Vol 174 (1-2) ◽  
pp. 115-126 ◽  
Author(s):  
J.J Colbert ◽  
Michael Schuckers ◽  
Desta Fekedulegn ◽  
James Rentch ◽  
Máirtı́n MacSiúrtáin ◽  
...  

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