Estimating the Density and Mortality of Juvenile Western Rock Lobsters (Panulirus cygnus) in Nursery Reefs

1990 ◽  
Vol 47 (7) ◽  
pp. 1330-1338 ◽  
Author(s):  
Bruce F. Phillips
Keyword(s):  
Frequency Analysis ◽  
Larval Settlement ◽  
Alternative Methods ◽  
Length Frequency ◽  
Density Dependent ◽  
Additional Information ◽  
Single Night ◽  
Panulirus Cygnus ◽  
Dependent Processes ◽  
Length Frequency Analysis

Studies of juvenile rock lobsters (Panulirus cygnus) in the nursery reefs of Western Australia indicated that density-dependent processes on the reefs were the major determinant of year-class strengths of recruitment to the fishery. Reassessment of early data, plus additional information, indicates that these estimates may have been inaccurate. Alternative methods of estimating juvenile densities were examined; application of length–frequency analysis to calculate the age-classes; visual estimates, and single-night trapping. Length–frequency analysis indicated that either immigration onto the test reefs had occurred, or the data were inaccurate. Visual estimates and single-night trapping were more rapid and used less manpower and resources than mark–recapture methods, but the estimates were of unknown accuracy. No truly satisfactory method of making reliable estimates of either the density of natural mortality rate of juveniles in the nursery reefs is yet available. Nevertheless, the data on the levels of larval settlement and subsequent catches, suggest that density dependent processes probably have a significant effect on the levels of recruitment to the fishery, although the upper level to this recruitment has not been reached over the past 20 yrs.

scholarly journals DINAMIKA POPULASI LOBSTER PASIR (Panulirus homarus Linnaeus, 1758) DI PERAIRAN PALABUHANRATU, JAWA BARAT

2018 ◽  
Vol 23 (3) ◽  
pp. 215 ◽  
Author(s):  
Zairion Zairion ◽  
Nefi Islamiati ◽  
Yusli Wardiatno ◽  
Ali Mashar ◽  
Rudi Alek Wahyudin ◽  
...  
Keyword(s):  
Frequency Analysis ◽  
Spiny Lobster ◽  
Total Sample ◽  
Optimum Level ◽  
Length Frequency ◽  
Recruitment Pattern ◽  
Exploitation Rate ◽  
Lobster Fishery ◽  
Average Size ◽  
Length Frequency Analysis

Dinamika populasi merupakan aspek penting sebagai dasar pengelolaan perikanan dan informasi tentang aspek tersebut pada lobster pasir masih minim di perairan Palabuhanratu. Tujuan penelitian ini adalah mengkaji aspek pertumbuhan, pola rekrutmen, mortalitas dan laju eksploitasi lobster pasir (Panulirus homarus) di perairan Palabuhanratu. Penelitian ini dilakukan periode Juni 2015-Mei 2016 dengan metode sensus. Lobster pasir hasil tangkapan jaring insang dasar dengan jumlah total sampel 483 ekor mempunyai panjang karapas antara 28-100 mm. Pola pertumbuhan berdasarkan hasil regresi linear memperlihatkan allometrik negatif. Hasil analisis menggunakan metode ELEFAN I (Electronic Length Frequency Analysis) menunjukan koefisien pertumbuhan lobster pasir jantan (K = 0,29 per tahun), lebih kecil dibandingkan dengan betina (K = 0,40 per tahun). Rekrutmen terindikasi dua puncak dalam setahun: yaitu pada Februari-Mei dan September-Oktober). Laju mortalitaskarena penangkapan (F) mencapai 1,9-2,2 kali laju mortalitas alami (M). Nilai Lc<Lrmemperlihatkan lobster pasir sudah tertangkap sebelum mencapaiukuran rata-rata mengerami telur atau ukuran kematangan reproduktif. Laju eksploitasi lobster pasir mencapai 32-38% di atas laju eksploitasi optimum, sehingga lobster pasir sudah mengalamieksploitasi yang berlebih.Population dynamics is an important aspect as basic of fisheries management and little information of this aspect for spiny lobster fishery in Pelabuhanratu waters. This research aims to evaluate of growth aspects, recruitment pattern, mortality, and exploitation rate of scalloped spiny lobster (Panulirus homarus) in Palabuhanratu waters. This research was conducted in June 2015 until May 2016 using census method. The size of P. homarus captured using bottom gill-net with total sample 483 specimen was between 28-100 mm carapace lengths (CL). Linear regression showed that growth pattern was negative allometric. The growth coefficient of male (K = 0.29 per year) was found smaller than female (K = 0.40 per year) based on ELEFAN I (Electronic Length Frequency Analysis) method. Recruitment seems to be accrued twice peaks a year (February to May and September to October) and the highest was at February to May. Fishing mortality (F) reached 1.9 to 2.2 times of natural mortality (M). The LcÂLr value showed that female has been caught before reached the average size of bearing eggs or reproductive maturity size. The exploitation rate of spiny lobsters reaches 32-38% above optimum level. This study suggests that the spiny lobster fishery in Palabuhanratu in the state of overexploitation.

scholarly journals Growth and age composition of northern shrimp Pandalus eous estimated by multiple length frequency analysis

2014 ◽  
Vol 80 (4) ◽  
pp. 665-678 ◽  
Author(s):  
Hiroshi Yamaguchi ◽  
Yoko Goto ◽  
Noboru Hoshino ◽  
Kazushi Miyashita
Keyword(s):  
Frequency Analysis ◽  
Length Frequency ◽  
Age Composition ◽  
Northern Shrimp ◽  
Length Frequency Analysis

Some Uses of Probability Paper in the Analysis of Size Frequency Distributions

1954 ◽  
Vol 5 (3) ◽  
pp. 513 ◽  
Author(s):  
RM Cassie
Keyword(s):  
Frequency Analysis ◽  
Length Frequency ◽  
Scale Reading ◽  
Frequency Distributions ◽  
Probability Paper ◽  
Size Frequency ◽  
Graph Paper ◽  
Probability Graph ◽  
Age Determinations ◽  
Length Frequency Analysis

Methods are described by which the component groups may be extracted from polymodal size frequency samples by the use of probability graph paper. Four examples are given illustrating: the solution of a distribution with more than two modes and with only one exposed flank; the coordination of fish age determinations by the two methods, length frequency analysis and scale reading; a bivariate sample where the two means coincide though the standard deviations are different; a method of correcting for truncation.

Selecting optimal bin size to account for growth variability in Electronic LEngth Frequency ANalysis (ELEFAN)

2020 ◽  
Vol 225 ◽  
pp. 105474 ◽  
Author(s):  
Kun Wang ◽  
Chongliang Zhang ◽  
Binduo Xu ◽  
Ying Xue ◽  
Yiping Ren
Keyword(s):  
Frequency Analysis ◽  
Length Frequency ◽  
Growth Variability ◽  
Length Frequency Analysis

A New Approach to Length–Frequency Analysis: Growth Structure

1980 ◽  
Vol 37 (9) ◽  
pp. 1337-1351 ◽  
Author(s):  
Jon Schnute ◽  
David Fournier
Keyword(s):  
Frequency Analysis ◽  
Likelihood Estimation ◽  
Von Bertalanffy ◽  
Length Frequency ◽  
New Approach ◽  
New Methods ◽  
The Mean ◽  
Standard Deviations ◽  
Using Data ◽  
Length Frequency Analysis

This paper presents a new approach to length–frequency analysis which takes account of biological structure in the mean lengths and standard deviations in length for various age-classes of fish. The new methods help determine biologically meaningful solutions, even when earlier methods lead to an ambiguous set of competing solutions. The structure of the standard deviations turns out to be especially important. For describing the means, new parameters are defined for von Bertalanffy growth which prove to have greater biological meaning and numerical stability than L∞, K, and t0. These new parameters can often be estimated easily from the raw data in cases where the species experiences a slowing of growth with age. This paper also presents χ2 methods which can be used to rank competing solutions, although the results are not definitive. All methods are illustrated using data previously published for pike and abalone. An appendix describes in detail the computer programs required for the analysis.Key words: length–frequency analysis, aging of samples, von Bertalanffy growth, growth, maximum likelihood estimation, nonlinear estimation

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