scholarly journals Multiyear tagging studies incorporating fishing effort data

1998 ◽  
Vol 55 (6) ◽  
pp. 1466-1476 ◽  
Author(s):  
John M Hoenig ◽  
Nicholas J Barrowman ◽  
William S Hearn ◽  
Kenneth H Pollock
Keyword(s):  
Mortality Rate ◽  
Additional Data ◽  
Survival Rates ◽  
Fishing Effort ◽  
Reporting Rate ◽  
Natural Mortality ◽  
Fishing Mortality ◽  
Recovery Rates ◽  
Sampling Survey ◽  
Tag Shedding

The Brownie models for multiyear tagging studies can be used to estimate age- and year-specific annual survival rates and tag recovery rates. The latter are composites of the exploitation rates and rates of tag reporting, tag shedding, and tag-induced mortality. It is possible to estimate the exploitation rates if the other components of the tag recovery rates can be quantified. Instantaneous rates of fishing and natural mortality can be estimated if information is available on the seasonal distribution of fishing effort. The estimated rates are only moderately dependent on the timing of the fishing; consequently, the relative effort data can be crude. Information on the timing of the catch over the course of the year can be used as a substitute for the effort data. Fishing mortality can also be assumed to be proportional to fishing effort over years; consequently, if fishing effort is known then the tag reporting rate, natural mortality rate, and a single catchability coefficient can be estimated (instead of natural mortality and a series of fishing mortalities). Although it is possible in theory to estimate both the tag reporting rate and the natural mortality rate with all of these models, in practice it appears necessary to obtain some additional data relating to tag reporting rate to obtain acceptable results. The additional data can come from a variable reward tagging study, a creel or port sampling survey, or from tagged animals that are secretly added to the fishers' catches.

The Effect of Reduction of Fishing Effort on Yield

1962 ◽  
Vol 19 (4) ◽  
pp. 521-529 ◽  
Author(s):  
Syoiti Tanaka
Keyword(s):  
Mortality Rate ◽  
Sudden Change ◽  
Japan Sea ◽  
Fish Population ◽  
Fishing Effort ◽  
Natural Mortality ◽  
Fishing Mortality ◽  
Yield Curves ◽  
Before And After ◽  
Steady Level

When a fish population has been depleted by heavy exploitation, with the yield from the population maintaining an unfavourable level, it is usual to expect that the situation will be improved by reduction of fishing effort. Following a sudden reduction of fishing mortality, p, from p1 to p2 at time τ = 0, the yield at once decreases and then increases gradually until it reaches another steady level higher than the former level.The present paper deals, using Baranov's model, with the transition stage of the population following a sudden change in p, as well as with the steady state before and after the change. Relations between equilibrium yield and fishing mortality rate (effort-yield curves) are calculated for various values of the parameters, λ0 (= l0/u, where l0 is the length of a recruit and u is the yearly increase in length), q (natural mortality rate), and b (remaining life span of a fish at the time of recruitment) (Fig. 2). It is noteworthy that for species that grow slowly after recruitment, i.e. when λ0 is large, reduction of fishing would have scarcely any effect on the yield (Fig. 4).Yield curves for the period of transition from the present to various lower levels of fishing are calculated for the case in which λ0 = 4, q = 0.15, b = 10 and p1 = 1.35. These represent parameters for the present state of the stock of sohachi flounders Cleisthenes herzensteini (Schmidt), in the southwestern area of the Japan Sea (Fig. 5).Possible density effects on growth rate and natural mortality rate, which are briefly discussed, appear to diminish considerably the effectiveness of any reduction in fishing effort (Fig. 6).

scholarly journals Estimating natural and fishing mortality and tag reporting rate of southern rock lobster (Jasus edwardsii) from a multiyear tagging model

2001 ◽  
Vol 58 (12) ◽  
pp. 2490-2501 ◽  
Author(s):  
S D Frusher ◽  
J M Hoenig
Keyword(s):  
Mortality Rates ◽  
Fishing Effort ◽  
Reporting Rate ◽  
Standard Errors ◽  
Natural Mortality ◽  
Fishing Mortality ◽  
Rock Lobster ◽  
Relative Standard ◽  
Jasus Edwardsii ◽  
Mortality Estimates

Fishing and natural mortality rates and tag reporting rate for rock lobsters (Jasus edwardsii) in northwest Tasmania, Australia, were estimated using multiyear tagging models. These estimates are necessary for assessment of the resource. Several models were examined that had either two or three tagging events each year, and either combined sexes or kept sexes separate. The model that best described the dynamics of the fishery utilized three tagging events within a year. The year was divided into discrete periods and, within each year, fishing effort and duration of period were used to apportion fishing and natural mortalities, respectively, to the periods. The separation of fishing mortalities by sex was not found to improve the models. Although high (1.0–1.2·year–1), the instantaneous fishing mortality estimates were comparable to estimates obtained from other methods and the relative standard errors were low. Reporting rate estimates were also precise and indicated a lack of participation by the fishing industry. Estimates of natural mortality were low (0.00–0.02·year–1) but imprecise.

scholarly journals BEBERAPA PARAMETER POPULASI UDANG PUTIH (Penaeus merguiensis de Mann) DI PERAIRAN TARAKAN, KALIMANTAN UTARA

2017 ◽  
Vol 9 (2) ◽  
pp. 85
Author(s):  
Umi Chodrijah ◽  
Ali Suman
Keyword(s):  
Mortality Rate ◽  
Total Mortality ◽  
Fishing Effort ◽  
Natural Mortality ◽  
Fishing Mortality ◽  
Population Parameters ◽  
Spawning Period ◽  
Exploitation Rate ◽  
First Maturity ◽  
Penaeus Merguiensis

Tingkat eksploitasi udang putih (Penaeus merguiensis) sangat intensif. Hal ini terindikasi dengan hasil tangkapan udang di WPP-NRI 716 selama 9 tahun terakhir meningkat. Tujuan penelitian ini untuk mengkaji beberapa parameter populasi dan aspek biologi udang putih di perairan Tarakan. Data panjang karapas dan tingkat kematangan gonad udang putih dikumpulkan dari tempat pendaratan udang di Selumit Pantai, Tarakan, Kalimantan Utara pada Januari sampai dengan November 2016. Pendugaan parameter populasi dengan aplikasi model analisis menggunakan program ELEFAN 1. Hasil penelitian menunjukkan rata-rata ukuran udang putih pertama kali tertangkap (Lc) pada panjang karapas 32,51 mm dan rata-rata ukuran pertama kali matang gonad 33,58 mm. Puncak musim pemijahan terjadi pada Maret dan Agustus. Laju pertumbuhan (K) sebesar 1,33 per tahun (betina) dan 1,55 per tahun (jantan). Laju kematian total (Z) sebesar 7,5 per tahun (betina) dan 8,85 per tahun (jantan), laju kematian alamiah (M) sebesar 1,82 per tahun (betina) dan 2,16 per tahun (jantan) serta laju kematian akibat penangkapan (F) sebesar 5,68 per tahun (betina) dan 6,69 per tahun (jantan). Laju pengusahaan (E) udang putih di perairan Tarakan adalah sebesar 0,76 per tahun. Hal ini menunjukkan tingkat pemanfaatan udang putih telah mengalami lebih tangkap (overfishing). Kondisi ini menggambarkan perlunya dilakukan pengurangan upaya sekitar 52 %.  The banana prawn (Penaeus merguiensis) have been exploited intensively. For instance, within nine years the number of shrimp production in FMA 716 increased dramatically. This research aims to identify the some population parameters of banana prawn in the Tarakan waters. This research was carried out from January to November 2016. Data were analyzed using the analytical model application with ELEFAN I. The result showed that the length at first capture (Lc) of banana prawn was 32,51 mmCL and the length at first maturity (Lm) was 33,58 mm CL. The peak season of spawning period was indicated on March and August. The growth rate (K) was 1,33 /year (female) and 1.55/year (male). Total mortality rate (Z) was 7.5/year (female) and 8,85/year (male), natural mortality rate (M) rate was 1.82/year (female) and 2.16/year (male) and fishing mortality rate ( F) were 5.68/ year (female) and 6.69/year (male). The exploitation rate (E) of banana prawn in the Tarakan waters was 0.76 per year. Therefore, level of existing fishing effort of the banana prawn should reduced about 52 % in the next year.

scholarly journals Growth Pattern, Mortality and Exploitation Rate of the Giant African Threadfin, Polydactylus quadrifilis (Cuvier, 1829) from Ebrié Lagoon (Potou Sector, Côte d’Ivoire)

2020 ◽  
pp. 33-42
Author(s):  
Théophile Aké Bédia ◽  
Bakari Coulibaly ◽  
Yao Aristide Konan ◽  
Essetchi Paul Kouamelan ◽  
Valentin N’douba
Keyword(s):  
Growth Rate ◽  
Mortality Rate ◽  
Growth Pattern ◽  
Total Mortality ◽  
Fishing Effort ◽  
Natural Mortality ◽  
Fishing Mortality ◽  
Population Parameters ◽  
Exploitation Rate ◽  
First Maturity

The study evaluated some population parameters of Polydactylus quadrifilis within Ebrié lagoon (Potou sector). Samples were obtained using artisanal gillnet fishery from April 2004 to March 2006. A total of 741 individuals of P. quadrifilis ranged from 11 to 70 cm were examined. Population parameters were estimated where asymptotic length (L∞) was found 60 cm, growth rate (K) 0.33 per year, the longevity (T max) 9.09 years, and growth performance index (Φ′) 3.06. The length at first capture (Lc50 = 10.60 cm) was lower than the length at first maturity (Lm50 = 40 cm). Total mortality rate (Z) was calculated as 1.10 per year including natural mortality and fishing mortality. The exploitation rate (E=0.36) was found to be less than the maximum exploitation rate (E max = 0.44) and indicated that P. quadrifilis is not overexploited. The current exploitation rate should be maintained by sustainable fisheries measures including monitoring of fishing effort.

scholarly journals Estimating fishing and natural mortality rates, and catchability coefficient, from a series of observations on mean length and fishing effort

2017 ◽  
Vol 75 (2) ◽  
pp. 610-620 ◽  
Author(s):  
Amy Y Then ◽  
John M Hoenig ◽  
Quang C Huynh
Keyword(s):  
Mortality Rate ◽  
Total Mortality ◽  
Fishing Effort ◽  
Residual Variance ◽  
Natural Mortality ◽  
Fishing Mortality ◽  
Norway Lobster ◽  
Rapid Growth Rate ◽  
Complex Models ◽  
The Mean

Abstract Gedamke and Hoenig (2006) (Transactions of the American Fisheries Society, 135: 476–487) developed a non-equilibrium version of the Beverton and Holt estimator of total mortality rate, Z, based on mean length and thereby increased the usefulness of length-based methods. In this study, we extend their model by replacing period-specific Z parameters with the year-specific parameterization Zy = qfy + M where q is the catchability coefficient, fy is the fishing effort in year y, F (=qf) is the fishing mortality rate, and M is the natural mortality rate. Thus, the problem reduces to estimating just three parameters: q, M and residual variance. We used Monte Carlo simulation to study the model behaviour. Estimates of q and M are highly negatively correlated and may or may not be reliable; however, the estimates of corresponding Z’s are more precise than estimates of F and are generally reliable, even when uncertainty about the mean lengths is high. This length-based method appears to work best for stocks with rapid growth rate. Contrast in effort data may not be necessary for reliable estimates of Z’s. This approach forms a bridge between data-limited models and more complex models. We apply the method to the Norway lobster Nephrops norvegicus stock in Portugal as an example.

Movement, Growth and natural mortality rate of the Red Spot King Prawn, Penaeus longistylus Kubo, from the Great Barrier Reef Lagoon

1990 ◽  
Vol 41 (3) ◽  
pp. 399 ◽  
Author(s):  
MCL Dredge
Keyword(s):  
Growth Rate ◽  
Mortality Rate ◽  
Great Barrier Reef ◽  
Annual Variation ◽  
Growth Parameters ◽  
Natural Mortality ◽  
Barrier Reef ◽  
Fishing Mortality ◽  
Nursery Areas ◽  
Reef Lagoon

Movement, growth and natural mortality rate of the red spot king prawn, Penaeus longistylus, occurring in waters of the Great Barrier Reef off Townsville, Queensland, were investigated in a series of tagging experiments. Adult P. longistylus did not migrate after leaving nursery areas. Their growth rate was slower than that of the conspecific species P. plebejus, and significant inter-annual variation in growth parameters was observed. The natural mortality rate, assessed by sequential tagging experiments that eliminated the possibility of confounding with the rate of fishing mortality, was estimated to be 0.072 (week-1).

Influence of errors in natural mortality estimates in cohort analysis

1997 ◽  
Vol 54 (7) ◽  
pp. 1608-1612 ◽  
Author(s):  
G Mertz ◽  
R A Myers
Keyword(s):  
Mortality Rate ◽  
Similar Pattern ◽  
Cohort Analysis ◽  
Transient Behavior ◽  
Natural Mortality ◽  
Exact Formulation ◽  
Fishing Mortality ◽  
Bias Factor ◽  
Special Case ◽  
Mortality Estimates

The accuracy of the estimation of cohort strength from catch data may be greatly degraded if a poor estimate of the natural mortality rate is entered into the calculation. A straightforward, exact formulation for the error in cohort reconstruction due to a misspecified natural mortality rate is presented. The special case of constant fishing mortality is particularly transparent, allowing the error to be segmented into easily interpreted terms. A change in the fishing mortality may result in a distinct hump in the transient behavior of the bias factor, rather than a simple monotonic adjustment. This implies a similar pattern in estimated cohort strength.

scholarly journals POPULATION DYNAMICS OF MALAYAN LEAF FISH (Pristolepisgrooti Blkr.) IN RANAU LAKE, SOUTH SUMATRA

2018 ◽  
Vol 24 (2) ◽  
pp. 125
Author(s):  
Sevi Sawetri ◽  
Subagdja Subagdja ◽  
Dina Muthmainnah
Keyword(s):  
Mortality Rate ◽  
Growth Parameters ◽  
Total Mortality ◽  
Natural Mortality ◽  
Fishing Mortality ◽  
Frequency Data ◽  
Length Frequency ◽  
Lake Ecosystems ◽  
Exploitation Rate ◽  
Length Frequency Data

The Malayan leaf fish or locally named as kepor (Pristolepis grooti) is one of important biotic components in Ranau Lake ecosystems. This study aimed to estimate population dynamic and exploitation rate of kepor in Ranau Lake, South Sumatera. The population parameters are estimated based on length frequency data which were collected in March to October 2013. Growth parameters and fishing mortality rates were calculated using FiSAT software package. The results showed that kepor’s growth was negative allometric, which tended to gain length faster than weight. Kepor population was dominated (42%) by individual length of 10.0 to 11.0 cm. Predicted length infinity (L) was 17.28 cm with high value of growth rates (K) of 1.4 year-1. The natural mortality rate (M) is 2.57 year-1, the fishing mortality rate (F) is 5.36 year-1 and total mortality rate (Z) is 7.93 year-1. The exploitation rate of Malayan leaf fish in Ranau Lake (E = 0.68 year-1) has passed the optimum score.  

scholarly journals Optimal fishing mortality assignment for southern hake Merluccius australis in Chile

2020 ◽  
Vol 48 (4) ◽  
pp. 613-625
Author(s):  
Felipe Lopez ◽  
Jorge Jimenez ◽  
Cristian Canales
Keyword(s):  
Mortality Rate ◽  
Economic Benefit ◽  
Mortality Rates ◽  
Fish Population ◽  
Fishing Effort ◽  
Economic Benefits ◽  
Historical Background ◽  
Total Catch ◽  
Fishing Mortality ◽  
Objective Functions

Since 1979, southern hake (Merluccius australis) has been exploited in Chile from the Bio Bio to the Magallanes regions, between the parallels 41°28.6'S and 57°S. There is evidence of a constant fishing effort and a sustained reduction of the fish population, consistent with a progressive decrease in total annual catches. Management strategies based on the maximum sustainable yield (MSY) and quota assignment/ distribution criteria have not been able to sustain acceptable biomass levels. A non-linear optimization model with two objective functions was proposed to determine an optimal total catch quota for more sustainable exploitation of this fishery. The first function maximizes the total catch over time in response to an optimal assignment of fishing mortality rates per fleet; the second function maximizes the total economic benefit associated with the total catch. The dynamics of the fish population were represented with the equations of a predictive age-structured model. Decision variables were fishing mortality rates and annual catch quotas per fleet, subject to constraints that guarantee a minimum level of biomass escape over a long-term period. The input parameters were obtained from the last stock evaluation report carried out by the Instituto de Fomento Pesquero (IFOP) of Chile. The historical background data of the fishery and the regulatory framework were relevant aspects of the methodology. Five scenarios were evaluated with the two objective functions, including a base scenario, which considered the referential mortality rate as input data as the average mortality rate per fleet from 2007 to 2012. Total economic benefits fluctuate between 102 and USD 442 million for total catches in the range of 108 to 421 thousand tons, which were obtained from maximizing the economic and biological objective functions. Economic benefit/catch ratios were reduced for scenarios with higher constraints on catch limits, and they were more efficient from a biological point of view. Situations with lighter constraints showed in general higher economic benefits and better performance ratios than those with stronger restrictions. The use of optimization models may provide a useful tool to evaluate the effect of regulations for adequate conservation and economical utilization of a limited resource.

Integrating catch-at-age and multiyear tagging data: a combined Brownie and Petersen estimation approach in a fishery context

2006 ◽  
Vol 63 (3) ◽  
pp. 534-548 ◽  
Author(s):  
Tom Polacheck ◽  
J Paige Eveson ◽  
Geoff M Laslett ◽  
Kenneth H Pollock ◽  
William S Hearn
Keyword(s):  
Mortality Rate ◽  
Population Size ◽  
Stock Assessment ◽  
Natural Mortality ◽  
Fishing Mortality ◽  
Catch Data ◽  
Coefficients Of Variation ◽  
Southern Bluefin Tuna ◽  
Catch Rates ◽  
Comprehensive Framework

A comprehensive framework for modelling data from multiyear tagging experiments in a fishery context is presented that incorporates catch data into the traditional Brownie tag–recapture model. Incorporation of catch data not only allows for improved estimation of natural and fishing mortality rates, but also for direct estimation of population size at the time of tagging. These are the primary quantities required to be estimated in stock assessments — having an approach for directly estimating them that does not require catch rates provides a potentially powerful alternative for augmenting traditional stock assessment methods. Simulations are used to demonstrate the value of directly incorporating catch data in the model. Results from the range of scenarios considered suggest that in addition to providing a precise estimate of population size (coefficients of variation ranging from ~15% to 30%), including catch data can decrease biases in the mortality rate estimates (natural mortality especially) and improve precision of fishing mortality rate estimates (by as much as 60% at age 1). The model is applied to southern bluefin tuna (Thunnus maccoyii) tag–recapture and catch data collected in the 1990s to provide estimates of natural mortality, fishing mortality, and abundance for five cohorts of fish.

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