A Catch-at-Length Analysis that Incorporates a Stochastic Model of Growth

1990 ◽  
Vol 47 (1) ◽  
pp. 184-198 ◽  
Author(s):  
Patrick J. Sullivan ◽  
Han-Lin Lai ◽  
Vincent F. Gallucci

A length-structured population model, which incorporates von Bertalanffy growth, is used to describe changes in population abundance over time. The model is incorporated into a catch-at-length algorithm that uses a nonlinear least squares approach to estimate relative abundance, fishing mortality, selectivity, and the von Bertalanffy growth parameters L∞ and k. The algorithm is applied to a simulated data set for Pacific cod (Gadus macrocephalus) and to catch data on Pseudotolithus typus and Decapterus russellii. The parameter estimates of Pacific cod obtained from this algorithm were comparable with the values that were originally used to simulate the data. Although the catch data of P. typus did not exhibit the full range of sizes present in the population due to differential vulnerability of the population to the fishery, the estimates of L∞ and k reflect the growth over the entire size range of the population. Other population estimates for P. typus were in agreement with observed biological information. The estimated growth parameters L∞ and k of D. russellii showed some discrepancy with the information available on mature individuals present in this fishery but appeared to adequately represent year 1 growth. The estimated population and exploitation parameters fit the observed catch-at-length. Estimates made with the catch-at-length approach can be improved by using auxiliary information that may be available on abundance, fishing effort, recruitment, and growth.

1992 ◽  
Vol 43 (5) ◽  
pp. 1283 ◽  
Author(s):  
RC Buckworth

Mark-recapture experiments, conducted near Groote Eylandt in the western Gulf of Carpentaria during 1984, were used to examine movements and growth of blue endeavour prawns, Metapenaeus endeavouri. The mean distance moved by tagged animals was only 12.7 (s.e.�1.0) km, but a few were recaptured > 100 km from their release sites. The mean time at liberty was 36.8 (�1.6) days, the maximum being 155 days. The distance and speed of movements were not related to the size or sex of tagged prawns. Nonuniform recapture patterns corresponded largely with fishing effort. Recaptures per unit effort (R/f analyses), used to account for nonuniform fishing effort, indicated that there was no directionality in movements. Thus, tagged specimens of M. endeavouri dispersed slowly across suitable adult habitat, with limited intermixing of adults from stocks around Groote Eylandt. Estimates of the von Bertalanffy growth parameters L∞ and K for each sex were obtained for data from summer and winter releases. The fit of the von Bertalanffy model to summer data was limited by the small number of recaptures. The fit of the model to winter data was improved by removing early recaptures, and these estimates are presented as the primary descriptors of growth in M. endeavouri. Parameter estimates did not differ significantly between seasons, but L∞ differed between sexes and K differed between sexes in winter. Predicted growth corresponded to the progression of modes in length-frequency data from commercial catches.


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.


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.


Author(s):  
Alexandra Garcia ◽  
João g. Pereira ◽  
Ângela Canha ◽  
Dália Reis ◽  
Hugo Diogo

Blue jack mackerel Trachurus picturatus monthly samples were collected between 1998 and 2011 to determine morphometric relationships, maturity, growth rates, reproduction and spawning seasonality in north-east Atlantic waters (ICES area Xa2). A total of 2895 specimens were sampled, ranging from 98 to 542 mm in fork-length (LF). The morphometric relationships (length-length and length-weight) showed statistically significant differences between sexes. Ages were estimated by counting growth bands on otoliths and verified by marginal increment analysis, with specimens ranging from 0 to 18 years. The von Bertalanffy models used to estimate growth parameters for both observed and back-calculated length-at-age data gave good fits. The gonads were analysed macroscopically and the spawning season found to occur from December to May. The length at 50% maturity for females and males occurred at 277 mm LF (4.3 years) and 288 mm LF (5.1 years), respectively. The results provide important biological information for fisheries assessment of a species that plays an important key role in the surrounding ecosystem.


2002 ◽  
Vol 59 (3) ◽  
pp. 424-432 ◽  
Author(s):  
Graham M Pilling ◽  
Geoffrey P Kirkwood ◽  
Stephen G Walker

A new method for estimating individual variability in the von Bertalanffy growth parameters of fish species is presented. The method uses a nonlinear random effects model, which explicitly assumes that an individual's growth parameters represent samples from a multivariate population of growth parameters characteristic of a species or population. The method was applied to backcalculated length-at-age data from the tropical emperor, Lethrinus mahsena. Individual growth parameter variability estimates were compared with those derived using the current "standard" method, which characterizes the joint distribution of growth parameter estimates obtained by independently fitting a growth curve to each individual data set. Estimates of mean von Bertalanffy growth parameters from the two methods were similar. However, estimated growth parameter variances were much higher using the standard method. Using the random effects model, the estimated correlation between population mean values of L[Formula: see text] and K was –0.52 or –0.42, depending on the marginal distribution assumed for K. The latter estimate had a 95% posterior credibility interval of –0.62 to –0.17. These represent the first reliable estimate of this correlation and confirm the view that these parameters are negatively correlated in fish populations; however, the absolute correlation value is somewhat lower than has been assumed.


2019 ◽  
Vol 8 (1) ◽  
pp. 85-93
Author(s):  
Maulvi Didit Baskoro ◽  
Edi Wibowo Kushartono ◽  
Irwani Irwani

Lobster pasir (Panulirus homarus) merupakan salah satu jenis lobster yang banyak di temukan di perairan Indonesia. Penelitian ini dilaksanakan pada bulan November 2017 sampai bulan Februari 2018 dengan lokasi pengambilan sampel di Pelabuhan Perikanan Samudra Cilacap (PPSC), di Perairan Cilacap Penelitian ini melihat bagaimana model pertumbuhan, dan status sumberdaya, mulai dari Von Bertalanffy, CPUE dan MSY. Estimasi parameter pertumbuhan lobster pasir (Panulirus homarus) dihitung dengan aplikasi Fisat II. Didapatkan hasil model pertumbuhan lobster pasir ( L∞ = 93.66 cm , K = 0.780 dan t0 -1.0950 mm). Hasil CPUE didapatkan persamaan, nilai linier sebesar  y = -0.0002 + 0.0965 x, nilai R2= 0,09443 untuk data lima tahun ke belakang terhitung dari 2012 sampai 2016 dalam upaya penangkapan (Panulirus sp.). Analisa Maximum sustainable yield (MSY) di lakukan untuk mengetahui besarnya potensi lestari Panulirus sp. dengan registrasi linier y-0.0002x + 0.965. Pendugaan MSY dan upaya penangkapan Foptimum diperoleh dengan 2412 trip dan nilai MSY 1164.031. Produksi Panulirus sp. di tahun 2016 – 2017 di Perairan Cilacap mengalami kenaikan, pada tahun 2016 terjadi kenaikan di bulan Februari, Maret, April dan Desember. Sedangakan pada tahun 2017 terjadi kenaikan di bulan Maret dan Oktober. Kenaikan ini dikarenakan musim lobster berada di bulan Oktober hingga Februari. Perubahan iklim dan penangkapan yang melebihi batas akan berpengaruh terhadap ukuran dan stok Panulirus sp. di alam. The Spiny lobster (Panulirus homarus) is one species of lobster that is widely found in Indonesian. This research was conducted on November 2017 until February 2018 the sample locations at the Cilacap (PPSC), which observed  the growth of models, and the status of resources, regretion Von Bertalanffy Growth function CPUE and MSY. The estimated growth parameters of sand lobster (Panulirus homarus) were  calculated using Fisat II application. The results of the spiny lobster  growth  model were obtained (L∞ = 93.66 cm, K = 0.780 and 0 -1.0950 mm). The CPUE results were obtained equations, linear values of y = -0.0002 + 0.0965 x for five years data from 2012 to 2016 . The Maximum Sustainable Yield (MSY) analysis was carried out to determine the magnitude of the sustainable potential of Panulirus sp. within linear  y-0.0002x + 0.965. The MSY values 1164,031 estimation and (Foptimum) fishing effort were 2.412 trips and MSY values 1164,031. The  production of Panulirus sp. start from  2016 to 2017 in the Cilacap has increased, the fact in 2016 there was an increase on February, March, April and December, while in 2017 there was an increase on March and October. So that the increase due to the lobster season being in October to February.  In addition, climate alteration and capture exceed the effect of  size and stock of Panulirus sp.


2018 ◽  
Vol 24 (3) ◽  
pp. 187
Author(s):  
Tirtadanu Tirtadanu ◽  
Umi Chodrijah

Salah satu informasi yang diperlukan untuk merumuskan pengelolaan kepiting bakau (Scylla serrata Forsskal, 1775) yang berkelanjutan adalah parameter populasi dan tingkat pemanfaatannya. Penelitian ini bertujuan untuk mengkaji parameter populasi dan tingkat pemanfaatan kepiting bakau di perairan Sebatik. Penelitian dilakukan pada Maret-Desember 2017. Sampel kepiting bakau di peroleh dari hasil tangkapan nelayan dengan alat tangkap bubu di perairan Sebatik. Pertumbuhan dianalisis berdasarkan persamaan Von Bertalanffy dengan mengamati pergeseran struktur ukuran kepiting tiap bulan dan tingkat pemanfaatan diperoleh dari metode kurva konversi panjang dengan hasil tangkapan. Hasil penelitian menunjukkan kepiting bakau yang tertangkap bubu di perairan Sebatik berukuran lebar karapas (carapace width) antara 84-144 mmCW dengan rata-rata ukuran yang tertangkap adalah 107,05±12,3 mmCW pada kepiting jantan dan 110,2±8,86 mmCW pada kepiting betina. Pertumbuhan berat kepiting bakau jantan lebih cepat dibandingkan ukurannya (b=3,6) sebaliknya pertumbuhan berat kepiting bakau betina lebih lambat dibandingkan ukurannya (b=2,5). Nisbah kelamin kepiting bakau menunjukkan kondisi tidak seimbang (5,5 : 1) dengan proporsi jantan lebih dominan dibandingkan betina. Lebar karapas asimptotik (CW) kepiting bakau jantan adalah 151,2 mmCW dan betina adalah 140,5 mmCW. Laju pertumbuhan (K) kepiting bakau adalah 0,75 tahun-1 pada kepiting jantan dan 0,79 tahun-1 pada kepiting betina. Status pemanfaatan kepiting bakau telah berada dalam tahapan mendekati lebih tangkap (E=0,5-0,55) sehingga disarankan tidak melakukan penambahan upaya penangkapan kepiting bakau di perairan Sebatik. One of the information needed for formulating the sustainable management of mud crab is the availability of information on the population parameters and its exploitation rate. The current research aimed to study the population parameters and the exploitation rate of mud crab in Sebatik Waters. Field research was conducted in March – December 2017. Samples of mud crab were obtained from the catch of fisherman by trap in Sebatik Waters. The Von Bertalanffy growth parameters were constructed through monthly modals progression analysis of the size of carapace width frequencies distributions and the exploitation rate was estimated through the method of length converted catch curve. The results showed that the carapace width of mud crabs caught by trap in Sebatik Waters ranged between 84 to 144 mmCW with the mean size of 107.05±12.3 mmCW for male and 110.2±8.86 mmCW for female. The growth of weights of male crab (b=3.6) is faster than its size, while the growth of weight of female crab was slower than its size (b=2,5). The sex ratio of mud crab was unbalanced (5.5 : 1) that the proportion of male was more dominant than female. Asymptotic carapace width (CW) of mud crab was 151.2 mmCW for male and 140.5 mmCW for female. The growth rate (K) of mud crab was 0.75 year-1 for male and 0.79 year-1 for female. The exploitation status of mud crab was starting to overfishing (E=0,5-0,55) so it suggest to not increase the fishing effort of mud crab fishery  in Sebatik Waters.


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.


1995 ◽  
Vol 52 (7) ◽  
pp. 1368-1375 ◽  
Author(s):  
Yoy-Gan Wang ◽  
Mervyn R. Thomas

Estimation of von Bertalanffy growth parameters has received considerable attention in fisheries research. Since Sainsbury (1980, Can. J. Fish. Aquat. Sci. 37: 241–247) much of this research effort has centered on accounting for individual variability in the growth parameters. In this paper we demonstrate that, in analysis of tagging data, Sainsbury's method and its derivatives do not, in general, satisfactorily account for individual variability in growth, leading to inconsistent parameter estimates (the bias does not tend to zero as sample size increases to infinity). The bias arises because these methods do not use appropriate conditional expectations as a basis for estimation. This bias is found to be similar to that of the Fabens method. Such methods would be appropriate only under the assumption that the individual growth parameters that generate the growth increment were independent of the growth parameters that generated the initial length. However, such an assumption would be unrealistic. The results are derived analytically, and illustrated with a simulation study. Until techniques that take full account of the appropriate conditioning have been developed, the effect of individual variability on growth has yet to be fully understood.


2019 ◽  
Vol 76 (8) ◽  
pp. 1326-1337 ◽  
Author(s):  
Kate McQueen ◽  
J. Paige Eveson ◽  
Bodo Dolk ◽  
Thomas Lorenz ◽  
Thomas Mohr ◽  
...  

Tag–recapture data contain valuable information about individual fish growth, which can enhance the estimation of growth parameters. Tag–recapture data are especially useful when age-determination uncertainties throw age-based growth estimates and stock assessments into question, as is the present situation with several important gadoid stocks. Length-based (GROTAG method) and age-based (LEP method) growth functions were fit to a large data set of tagged and recaptured cod (Gadus morhua) from an artificial reef in the western Baltic Sea to calculate improved growth parameter estimates. The LEP method allowed integration of different data formats, including tag–recapture, length frequency, and length-at-age, to estimate a more robust and comprehensive growth function (von Bertalanffy growth parameters: L∞ = 154.56 cm, k = 0.11, t0 = –0.13). Two heavily exploited cod stocks inhabit the Baltic Sea, subsisting at the upper thermal and lower salinity limits of the species. Otolith shape analyses indicated that, unexpectedly, individuals from both populations were resident at the reef. Compared with cod populations elsewhere, cod in the western Baltic Sea grow relatively slowly and with weak seasonal fluctuations in growth rates, potentially due to adverse conditions for growth.


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