Length Frequency Data Research Articles

Length-weight relationship, growth and mortality ofAnadara granosain Penang Island, Malaysia: an approach using length-frequency data sets

Length-weight relationship, growth parameters and mortality rates ofAnadara granosain the intertidal zone of Balik Pulau, Penang Island, West Coast of Malaysia were investigated based on monthly length-frequency data (December 2011 to November 2012). A total of 548 individuals ranging from 11.25 to 33.13 mm size were subjected to analysis. Logarithmic relationship between the length and weight was LogW = 2.328LogL − 2.537 (R2 = 0.922) for combined sexes. From this equation it was clear that the exponent ‘b’ value forA. granosashowed a negative allometric growth (b < 3). A von Bertalanffy growth function with an asymptotic length (L∞) of 35.40 mm and a growth constant (K) of 1.1 year−1was established from length frequency distributions. Thet0(−0.140) was estimated by substituting theL∞andKin the Pauly's equation. The sizes attained byA. granosawere 10.13, 14.36, 17.89, 20.82, 23.56 and 25.29 mm at the end of 2, 4, 6, 8, 10 and 12 months, respectively. The estimated growth performance index (Ø) was 3.13 while the estimated lifespan of the cockles was about 2.72 years at the study area. The estimated value of total mortality based on length-converted catch curve wasZ = 3.02 year−1. The natural mortality (M) and fishing mortality (F) rates were 1.84 and 0.48 year−1, respectively. The exploitation level (E) ofA. granosawas 0.20, which indicated slight fishing pressure on the stock.

Population dynamics of Japanese threadfin bream Nemipterus japonicus from Pakistani waters

Japanese threadfin bream Nemipterus japonicus (Bloch, 1791) is among the most abundant and commercially important species in Pakistan. From the coast of Pakistan, four demersal trawl surveys in October–November 2009 and May–June, August, October and November in 2010 were carried out. The purpose of this study is to estimate the population dynamics and status of the stock of the N. japonicus from Pakistani waters based on the research trawl surveys from the research area. The data consist of n=784 length-weight pairs and n=7 530 length frequency with the maximum length and weight of 29 cm and 358 g respectively. The length frequency data were analyzed using ELEFAN method in FiSAT computer package. The parameters of length and weight relationship were b=2.778, a=0.032 and R 2=0.973. The estimated von Bertalanffy growth function parameters were L ∞=30.45 cm, K=0.270 year−1. Based on length-converted catch curve analysis the total mortality (Z) during this study was estimated at 0.960 year−1. The natural mortality coefficient (M) was 0.74 year−1 using Pauly’s equation (the annual average sea surface temperature was 27°C), therefore, the fishing mortality coefficients (F) were 0.22 year−1. The yield per recruit analysis indicated that when t c was 2, F max was estimated at 1.2 and F 0.1 at 1.1. When t c was 1, F max was estimated at 0.95 and F 0.1 at 0.8. Because current age at first capture is about 1 year and F current was 0.22, F current is smaller than F 0.1 and F max, which indicated that the fishery is about in a safe condition. When using Gulland (1971) biological reference point, F opt was equals to M (0.74). The current fishing mortality rate of 0.22 was smaller than the target biological reference point.

An integrated Bayesian modeling approach for the growth of Indian Ocean yellowfin tuna

The Indian Ocean Tuna Tagging Program provided a unique opportunity to collect demographic data on the key commercially targeted tropical tuna species in the Indian Ocean. In this paper, we focused on estimating growth rates for one of these species, yellowfin (Thunnus albacares). Whilst most growth studies only draw on one data source, in this study we use a range of data sources: individual growth rates derived from yellowfin that were tagged and recaptured, direct age estimates obtained through otolith readings, and length-frequency data collected from the purse seine fishery between 2000 and 2010. To combine these data sources, we used an integrated Bayesian model that allowed us to account for the process and measurement errors associated with each data set. Our results indicate that the gradual addition of each data type improved the model's parameter estimations. The Bayesian framework was useful, as it allowed us to account for uncertainties associated with age estimates and to provide additional information on some parameters (e.g., asymptotic length). Our results support the existence of a complex growth pattern for Indian Ocean yellowfin, with two distinct growth phases between the immature and mature life stages. Such complex growth patterns, however, require additional information on absolute age of fish and transition rates between growth stanzas. This type of information is not available from the data. We suggest that bioenergetic models may address this current data gap. This modeling approach explicitly considers the allocation of metabolic energy in tuna and may offer a way to understand the underlying mechanisms that drive the observed growth patterns.

Length-Weight Relationship and population parameters of Pellonula leonensis Boulenger, 1916 (Clupeidae) in man-made Lake Taabo (Bandama basin; Côte d’Ivoire)

Length-Weight relationship and population parameters of Pellonula leonensis Boulenger, 1916 were studied in man-made Lake Taabo (Cote d’Ivoire). Samples were collected using beach seine with 6 and 8 mm mesh size from November 2008 to October 2009. Length frequency data collected were analyzed with FISAT software using the ELEFAN package to estimate the population parameters of Pellonula leonensis. The coefficient of allometry (b) was 3.24 and the correlation coefficient (r = 0.97) showed that there was a high and significant correlation between the standard length and the weight of P. leonensis. The asymptotic length (L∞) and growth rate constant (K) were estimated to be 6.56 cm and 0.86 year–1. Based on these growth parameters, the estimated value for the fishing mortality coefficient (F) was 0.93 year–1 for P. leonensis in man-made Lake Taabo. Natural mortality coefficient (M) estimated was 2.55 year–1 and exploitation rate (E) was 0.27. The recruitment pattern of P. leonensis showed that there is a year round recruitment with the highest recruitment in April (24.84%) while the lowest recruitment were in November (0.42%) and December (0%).

Determination of some population parameters of the veined rapa whelk (Rapana venosa) in the Central Black Sea

The veined rapa whelk is one of the most important invasive species in the Black Sea ecosystem since the 1940s. Following its introduction to the Black Sea, it destroyed most of the bivalve populations, mainly the Mediterranean mussel and oysters. However, the veined rapa whelk has commercial importance for the Black Sea fisheries as an alternative product. In this study, we aimed to determine some population parameters of the veined rapa whelk based on indirect ageing through length–frequency data by using the Bhattacharya method. We collected 1704 specimens by dredging along the coasts of Samsun Province in the Central Black Sea in 2011 from June to November. The age of the population varied from 0 to 6. Von Bertalanffy growth parameters were estimated as L∞ = 112.35 mm, k = 0.310, t0 = −0.486 and W∞ = 243.94 g. Mean length and weight, length–weight relationship, mortality and exploitation rates were derived as L = 56.80 ± 0.36 mm, W = 45.67 ± 0.89 g, W = 0.0006 L2.719, Z = 0.96, M = 0.57, F = 0.39 and E = 0.40, respectively.

Population dynamics of the shrimp Penaeus semisulcatus in the Yemeni Red Sea waters

Length-based analyses were conducted to assess the stock of the green tiger shrimp Penaeus semisulcatus. Monthly carapace length frequency data were collected from commercial catches at two main landing sites on the Yemeni Red Sea coast for eight months. Growth parameters, mortalities, exploitation rate and yield per recruit were estimated for this species in this area. The estimated growth parameters were CL∞ = 44.65 mm, K = 1.2 yr -1 and to = 0.15 for males and CL∞ = 58.8 mm, K = 1.4 yr -1 and to = -0.12 for females. The natural mortality coefficient (M) was estimated as 2.19 yr -1 and 2.27 yr -1 for males and females respectively. The total mortality coefficient (Z) was 6.55 yr -1 for males and 5.63 yr -1 for females. The exploitation rate was 0.67 and 0.60 for males and females, respectively. Yield per recruit analysis showed that the current exploitation rate will result in higher stock biomass than the maximum exploitation rate.

Distribution, Composition, and Abiotic Environment of Silver Rasbora (Rasbora argyrotaenia Blkr) Fish in Upstream Areas of Barito Watershed, South Kalimantan

This study aims to find scientific data concerning distribution pattern of R. argyrotaenia , catch composition of R. argyrotaenia including length frequency data, fishing peak season, spawning season, and abiotic characteristics of aquatic environment, such as life of R. argyrotaenia . The findings indicate that distribution pattern of R. argyrotaenia during rainy season (January-April) is scattered in main river, tributary, and marsh (flood plain), during dry season (May-August), position of fish is in main river and tributary, while in transitional months (September-December), fish is concentrated in main river. Fishing peak season occurs in April, May, June, and July reaching average haul range of 9.98 kg/month + 0.62-12.63 kg/month + 1.08. Based on Analysis of Progression Model by utilizing FISAT II on length-based data of R. argyrotaenia , there found three cohorts by average length of 65.76 mm + 9.0, 116.13 mm + 15.0, and 156.63 mm + 4.7. Referred to analysis of the Von Bartalanffy growth curve, it is known that inital spawning season of R. argyrotaenia alleged that the peak spawning season occurs in September, October, November and December reaching value of Linf=173.25, K=0.510/year, and t0=0.02. R. argyrotaenia lives in habitat where average temperature is 25.5 oC + 0.12 – 31.6 oC + 0.12, current speed of 0.06 ms-1+ 0.02 – 0.27ms-1 + 0.02, pH of 4.23 + 0.03 – 6.74 + 0.05, and DO of 4.2 mg l-1 + 0.06 – 7.5 mg l-1 + 0.10.

Coexistencia de <i>Lutjanus peru y Lutjanus guttatus</i> (Pisces: Lutjanidae) en la costa de Guerrero, México: relación con la variación temporal en el reclutamiento

Monthly volumes of capture of Lutjanus peru and Lutjanus guttatus from the coast of Guerrero, Mexico, were analyzed considering eight annual cycles. Time-series, auto correlation, and cross-correlation analysis showed that monthly abundance of populations display unsystematic variations. The FiSAT software was used to obtain the recruitment patterns of both species, using length-frequency data. Our results support the hypothesis that temporal phase-shifts in reproductive events, hence recruitment, explain the coexistence of these species. The outcome of this mechanism is a temporal succession of specific recruit abundance off the coasts of Guerrero, Mexico. The uncoupling of the recruitment events between these species, induces a separation of recruits: therefore, the intake of a particular set of preys could take place at different times.

Population dynamics of accidentally introduced Amazon sailfin catfish, Pterygoplichthys pardalis (Siluriformes, Loricariidae) in Pologolla reservoir, Sri Lanka

Many fish species have been introduced either intentionally or accidentally into Asian freshwaters and some species have been disreputed as alien invasive species (AIS) due to their potential threats to the biodiversity. In Polgolla reservoir of Sri Lanka, there is an established population of Pterigoplichthys pardalis, which makes a significant negative impact on the commercial fishery targeting exotic cichlid species as this armored catfish damages gillnets of the fishery. In the present study, an attempt was made to investigate population dynamics of P. pardalis in Polgolla reservoir with a view to ascertaining possibilities for commercial level exploitation of the fish stock. The fish landing sites in the reservoir were visited 4-6 days a month from May to November 2004 to collect data on species composition of landings and length frequency data of P. pardalis. P. pardalis accounted for 21% of the landings and von Bertalanffy growth parameters estimated by length-based stock assessment methodologies using FISAT II software were asymptotic total length of 41.3 cm and growth constant of 0.3 yr-1. Total mortality, natural mortality and fishing mortality were 0.76 yr-1, 0.73 yr-1 and 0.03 yr-1 respectively. Relative yield-per-recruit analysis indicated that there would be a great potential to optimize the fishery by increasing exploitation ratio from the present level of 0.4 to 0.7, while increasing length at first capture from the present level of 17.8 cm to 23 cm. However, as the consumer demand for this species is presently very poor, intensification of the fishery is possible only if market demand for P. pardalis is established through value addition by post-harvest technology.DOI: http://dx.doi.org/10.4038/sljas.v18i0.7040Sri Lanka J. Aquat. Sci. 18 (2013): 37-45

A nonparametric model of empirical length distributions to inform stratification of fishing effort for integrated assessments

Length frequency data (LFD) are an important input to integrated stock assessments, and statistical tests for variables that significantly influence the length distribution of fish can assist in the definition of effort strata, typically denoted as fisheries or sub-fisheries, in order to account for important systematic differences due to availability and/or gear-specific selectivity of size classes. Here, a nonparametric model of the probability density function of lengths is described which, instead of fitting to LFD directly, is fitted to the set of length quantiles for a pre-determined set of corresponding probabilities p (in this instance 0.05, 0.1–0.9 in 0.1 increments, and 0.95). These length quantile data (LQD) can be constructed with individual hauls as sampling units or after pooling hauls to sampling units defined by combinations of covariates such as gear type, spatial block, depth strata, or the sex of sampled fish. The length quantiles are modelled as a Gaussian response variable using a Generalised Additive Mixed Model (GAMM) with smoothing splines fitted for each combination of the covariates (i.e. gear type, depth strata and sex). Graphical presentation of the fitted splines along with standard error of difference bounds were used to investigate where differences were significant in order to assist in the optimal definition of sub-fisheries. The model has the advantage of greater generality and sensitivity in detecting differences compared to modelling a single quantile such as the median. In addition, fitting splines allows flexible and parsimonious modelling of length distributions of any shape. The model is demonstrated using LQD from commercial fishing for Patagonian toothfish at Heard Island.

Use of the SLW index to calculate growth function in the sea cucumber Isostichopus badionotus.

Age and growth analysis is essential to fisheries management. Indirect methods to calculate growth are widely used; however, length frequency data analysis in sea cucumbers is complicated by high data variability caused by body wall elasticity. Here we calculated Isostichopus badionotus parameters of the von Bertalanffy growth function. In order to address bias produced by body wall elasticity, we compared the performance of four measurements and one compound index that combines different biometric parameters: the square root of the length-width product (SLW). Results showed that variability in length data due to body wall elasticity was controlled by using body length (Le) from the SLW compound index. Growth in I. badionotus follows a negative allometric tendency. Slow or zero growth periods were observed during October and November, when weather conditions were adverse.

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

We examined growth of northern shrimp Pandalus eous in the Sea of Japan, off western Hokkaido, to improve estimations of catch-at-age for stock assessment. Multiple length frequency analysis based on length frequency data collected by a scientific research vessel was conducted to examine length-at-age in the shrimp population. Multi-normal distributions estimated using maximum likelihood indicated a good fit to length distributions. AIC values and regression analyses revealed annual growth variation and a decreasing trend in the length at several age classes in the shrimp population. We revised the method for estimating catch-at-age from the age-conversion table (ACT), which is a simple method for age determination, to age–length keys (ALK) calculated from the results of multiple length frequency analysis. Abundant year classes caught successively year after year could be more easily identified from the catch-at-age data computed using ALK than by using ACT. Our results suggested not only that the mean size of commercial landings fluctuated based on changes in age composition but also that a decrease in the length-at-age in the population influenced the consistent size decrease of commercial landings.

Population parameters of Rastrelliger kanagurta (Cuvier,1816) in the Marudu Bay, Sabah, Malaysia

An investigation of the population parameters of Indian mackerel, Rastrelliger kanagurta (Cuvier, 1816) in the Marudu Bay, Sabah, Malaysia was carried out from January to September 2013. The relationship between total length and body weight was estimated as W=0.006TL3.215 or Log W=3.215LogTL – 2.22 (R2=0.946). Monthly length frequency data of R. kanagurta were analyzed by FiSAT software to evaluate the mortality rates and its exploitation level. Asymptotic length (Lµ) and growth co-efficient (K) were estimated at 27.83 cm and 1.50 yr-1, respectively. The growth performance index (φ') was calculated as 3.07. Total mortality (Z), natural mortality (M) and fishing mortality (F) was calculated at 4.44 yr-1, 2.46 yr-1 and 1.98 yr-1, respectively. Exploitation level (E) of R. kanagurta was found to be 0.45. The exploitation level was below the optimum level of exploitation (E=0.50). It is revealed that the stock of R. kanagurta was found to be still under exploited in Marudu Bay.

Improving catch prediction for tiger prawns in the Australian northern prawn fishery

Abstract Population models form the basis for the assessments of species in the tiger prawn component of Australia's northern prawn fishery. Penaeus semisulcatus and P. esculentus are assessed using a size-structured population model. These assessments form the basis for a control rule which predicts future total allowable catches (TACs) for P. semisulcatus and P. esculentus so that the discounted profit from the fishery is maximized. However, there are concerns with this approach: (i) the TAC predictions have consistently overpredicted actual catches and (ii) the assessment for one of the species exhibits a retrospective pattern. A series of analyses was conducted to explore the causes of these observations. Results indicate that catch, effort, and recruitment prediction can be improved substantially by changing the assumed selectivity pattern for one of the surveys, changing how the length frequency data are assembled from the raw data collected, changing the constraints on the minimum amount of effort by target fleet, modifying how the distribution of effort by week is forecasted, and dropping the length frequency data from the most recent recruitment survey. More generally, the analyses illustrate how retrospective analysis can be used to improve how assessments and projections are undertaken when the quantities of interest are known retrospectively.

Hook selectivity of Giant Trevally (Caranx ignobilis) and Nakedbreast Trevally (Carangoides gymnostethus) (Carangidae) caught in the hook-and-line fishery off Negombo, Sri Lanka

In the present study, an attempt was made to quantify hook selectivity of two carangid species (Caranx ignobilis and Carangoides gymnostethus) which were predominantly caught in the hook-and-line fishery off Negombo, Sri Lanka. As the length frequency data of C. ignobilis and C. gymnostethus recorded by hook size were skewed towards the larger fish, a modification of Baranov-Holt method for gillnet selection was employed. For both species there were positive significant relationships (p<0.001) between the hook size and optimal length while selection range was negatively related to hook size (p<0.001). DOI: http://dx.doi.org/10.4038/sljas.v16i0.6712 Sri Lanka J. Aquat. Sci. 16 (2011): 11-26

Growth and mortality of two small fishes, Toxabramis swinhonis Günther, 1873 and Hyporhamphus intermedius (Cantor, 1842), in a Yangtze shallow lake (China) assessed by length frequency analysis

This study examined the growth and mortality of two widespread small fish species, Toxabramis swinhonis (Cyprinidae) and Hyporhamphus intermedius (Hemiramphidae), from a shallow lake (Niushan Lake, China) along the Yangtze River, by analyzing monthly length frequency data (July 2005 to June 2006) with the FAO-ICLARM stock assessment tool (FiSAT). Estimated von Bertalanffy growth equation parameters were: L (asymptotic length)=145mm TL, and K (growth coefficient)=0.66year(-1) for T.swinhonis; L=189mm TL, and K=0.68year(-1) for H.intermedius. The instantaneous rates of natural mortality (M) calculated for T.swinhonis and H.intermedius were 1.35 and 1.28year(-1), respectively. The length-converted catch curve method gave the total annual instantaneous mortality rate (Z) of 2.92year(-1) for T.swinhonis and 1.53year(-1) for H.intermedius. Recruitment patterns of both species were continuous, displaying a single major peak event per year. Despite not being of direct fishing interest, T.swinhonis, with high abundance and productivity as indicated by a high Z-value, can be an important species in fisheries management as an excellent food source for aquatic organisms, especially for larger fishes of economic value. These results represent the first information on population characteristics of T.swinhonis and H.intermedius, and constitute a comparison base for future growth studies in other lake environments.

Investigating the influence of length–frequency data on the stock assessment of Indian Ocean bigeye tuna

Most integrated stock assessment models are fitted to alternative sources of data like indices of abundance and length/age composition of catches in specific fisheries. While indices of abundance are often standardized over time, not much attention is paid to the temporal stability of the length/age data. A sequential approach to fitting model outputs to all sources of data, varying the weight given to the length composition data, for Indian Ocean bigeye tuna (Thunnus obesus) was examined in this paper. Logistic, double normal, and cubic spline selectivity functions were used to model the size composition of catches in the main industrial fisheries (longline and purse seine). Overall, there was a poor fit of stock assessment models to the individual length frequency observations collected from these fisheries, although marginal improvements of fit was made when temporally variable selectivity was implemented in the Stock Synthesis framework using the above described functions. The most influential factor in the assessment was the weighting of the length composition data relative to the indices of stock abundance. Contradictory signals between these two data sources have a large effect on spawning biomass dynamics, and inference based on these weightings can produce different management conclusions. We emphasized that understanding the data was the key to performing a well-calibrated stock assessment, and further refinements to the approach pursued in the analysis presented are discussed.

Parámetros de crecimiento y variaciones de densidad de una población de Strombus gigas (Neotaenioglossa: Strombidae), del parque Xel-Ha área natural protegida

The queen conch, Strombus gigas, is a gastropod of commercial importance in the Caribbean. Population studies are based on size frequency analysis, using either length or weight parameters for the whole live organism. This contribution used mark-recapture data to estimate the Von Bertalanffy equation parameters and population number variation within a non harvest population from a protected area, to clarify the biometric parameters that better suit for the whole population, or for the juvenile and adult fractions. Conchs from Xel-Ha Park were monthly sampled from November 2001 to August 2005. Every conch found was measured and marked with a numbered tag that identified month and locality; and monthly abundance was estimated with Jolly's method. Length, lip thickness and weight increments were used to estimate the Von Bertalanffy growth equation parameters with Appeldoorn's subroutine of FISAT program. The population number varied through the study, with a minimum of 49 in April 2003 and maximum of 9 848 during June 2005. Conchs make only temporary use of Xel-Ha cove. Shell length gave the best fit for the juvenile fraction: L(infinity)=251, K=0.3, C=0.8 Wp=0.3; and lip thickness for adults: L(infinity)=47.78, K=0.17, C=0.1, Wp=0.86, while, the whole population was better represented by weight: L(infinity)=3850, K=0.36, C=0.8, Wp=0.3. A maximum age of 19 years was estimated from the population. Natural mortality was 0.49/year for juveniles and 0.29/year for adults. There were two pulses of recruitment: fall-winter and summer. It is concluded that population studies from length frequency data, should be analyzed independently in two groups, shell for the juvenile fraction and lip thickness for the adult fraction, or if it is not possible to analyze the population fractions separately, weight should be used to avoid miss calculation of the age structure.

Stock Assessment of Bartail Flathead (Platycephalus indicus Linnaeus, 1758) in Northwest of Persian Gulf, Iran

Platycephalus indicus (bartail flathead) is dominant species of Platycephalidae family in Iran's southern waters, especially Khuzestan province and mainly is captured by bottom trawl and gillnet. The population biology of this species in the northwest waters of Persian Gulf (Iran) was investigated to derive information required for its management. Parameter values of the von Bertalanffy growth Function fit to size at length frequency data (males and females combined) were: k = 0.5year −1 , L∞ = 62.16 cm, to = −0.26 years. The estimated valve of total mortality, natural mortality, fishing mortality and Exploitation ratio (males and females com- bined) was: Z= 2.59 year -1 , M= 0.77 year -1 , F= 1.82 year -1 and E= 0.70, respectively. Exploita- tion rate, U and Annual total stock at beginning of year were 0.64 and 1194 T respectively. Annual average standing stock, b= 420 T, MSY= 544 T and MCY=362 T were estimated re- spectively. Result in this study showed exploitation ratio the bartail flathead stock is lower MSY and upper MCY. The results of the study highlight critical resource base issues and pro- vide the direction for the future management of this species in the northwest waters of Persian Gulf.

Fishery biology of Catfish (Chrysichthys auratus, Family: Bagridae) from Damietta branch of the River Nile, Egypt

The study of fishery biology of Chrysichthys auratus from Damietta branch, Egypt showed that the population has SL range of 7–20cm, L′=11.85cm. Males represent 45.90% and females 53.98% of the population. Length–length and length–weight relationships were analyzed for males, females and combined sexes. It was: SL=−0.6231+0.8402 TL and LogW=−1.6253+2.9832 LogSL for combined sexes, respectively. The highest values of condition factor were obtained in July, August and September for both sexes. The mean value of (K) for males was higher than those of females in all different lengths. Age was assessed by Bhattacharya’s (1967) method from length frequency data to estimate the von Bertalanffy growth parameters (L∞=26.53cm, K=0.214 and to=−1.569). The individuals of this species live for about 4years and the first age dominates the population. The growth performance index in length (ФL) and weight (Фwt) was estimated as 2.18 and 1.11, respectively. The mortalities were computed as: Z=1.44, M=0.60 and F=0.84. The exploitation rate was estimated as Ecur=0.58. Length at first capture (Lc) was 9.66cm at age 0.54years. Length at recruitment (Lr) was 8.49cm and age 0.35years. It was found that the stock of Chrysichthys auratus in Damietta branch was rationally exploited.