scholarly journals Exploitation status and stock assessment of the smooth clam Callista chione (Linnaeus, 1758) in the northern Alboran Sea (GSA01-W Mediterranean Sea)

2018 ◽  
Vol 19 (1) ◽  
pp. 1
Author(s):  
JORGE BARO ◽  
TERESA GARCIA ◽  
JAVIER URRA ◽  
MATIAS LOZANO ◽  
JOSE LUIS RUEDA
Keyword(s):  
Stock Assessment ◽  
Economic Value ◽  
Maximum Sustainable Yield ◽  
Reference Points ◽  
Production Model ◽  
Total Biomass ◽  
Alboran Sea ◽  
Callista Chione ◽  
Exploitation Status ◽  
Alborán Sea

The smooth clam, Callista chione (Linnaeus, 1758), is a venerid bivalve widely appreciated in southern Spain where it represents the top commercial bivalve species in terms of landings and economic value. In this area, a total of 223 artisanal boats (68% of the artisanal fleet) are involved in shellfishing targeting bivalve molluscs, including the smooth clam. The artisanal mechanised dredging that targets C. chione in the northern Alboran Sea is described and the current exploitation status of its populations is analysed. A surplus-production model was run using ASPIC and used to assess the temporal variation in the levels of fishing for this bivalve throughout the study period (2002-2015), as well as to suggest conservation reference points that could guarantee the sustainable exploitation of this resource. During the study period, the maximum C. chione catch was registered in 2003 (306 t) and the minimum in 2006 (93 t). The ASPIC model for C. chione stock suggests that a Maximum Sustainable Yield (MSY) of 216 t could be produced from a total stock biomass of 983 t (Bmsy) at a fishing mortality rate of total biomass of 0.22 (Fmsy), with B/Bmsy and F/Fmsy values of 1.34 and 0.82, respectively, indicating that the stock is approaching good status.

AZOV SEA VIMBA INDICATOR ASSESSMENT OF THE STATE OF FISH POPULATION IN TERMS OF LACK OF BIOLOGICAL DATA BY LBI MODEL

Fisheries ◽  
2021 ◽  
Vol 2021 (3) ◽  
pp. 68-75
Author(s):  
Inna Kozobrod ◽  
M. Pyatinsky ◽  
Elena Vlasenko
Keyword(s):  
Stock Assessment ◽  
Fish Population ◽  
Maximum Sustainable Yield ◽  
Biological Data ◽  
Reference Points ◽  
Population Characteristics ◽  
Small Scale ◽  
Assessment Procedure ◽  
Indicator Method ◽  
Yield Level

Stock assessment of vimba population Vimba vimba (Linnaeus, 1758) in period 2015–2020 was performed by qualitative indicator method LBI (Length-Based Indicators) that allows to assess qualitative characteristics of the population and fisheries and MSY biological reference points. The indicator, qualitative approach to stock assessment was applied due to absence vimba population of stable stock-recruitment relationship (due to artificial reproduction exist), which makes impossible to apply surplus production approach to solve production equation dB/dt. LBI model was performed based on available length-weight vimba frequencies dynamics information, which allows to evaluate qualitative population characteristics and fisheries impact. Model results shows no overexploitation signals: in period 2015–2020 fisheries are carried out in maximum sustainable yield level. Indicator results according to reference points indicate no significant signals of reduction optimal length class (Lopt), small-size or large-size class. In 2016 and 2018 uncertain overexploitation of small-scale classes leads to no significant changes was underlined. In terms of biological and fisheries data lacking, LBI methods allow to perform stock assessment procedure more stable and robust then surplus or cohort approach, and output scientific advice to fisheries management.

scholarly journals Fisheries Reference Point and Stock Status of Croaker Fishery (Sciaenidae) Exploited from the Bay of Bengal, Bangladesh

2022 ◽  
Vol 10 (1) ◽  
pp. 63
Author(s):  
Partho Protim Barman ◽  
Md. Mostafa Shamsuzzaman ◽  
Petra Schneider ◽  
Mohammad Mojibul Hoque Mozumder ◽  
Qun Liu
Keyword(s):  
Bay Of Bengal ◽  
Maximum Sustainable Yield ◽  
Reference Points ◽  
Production Model ◽  
Fishing Pressure ◽  
Surplus Production ◽  
Stock Status ◽  
Management Measures ◽  
Production Models ◽  
The Monte Carlo Method

This research evaluated fisheries reference points and stock status to assess the sustainability of the croaker fishery (Sciaenidae) from the Bay of Bengal (BoB), Bangladesh. Sixteen years (2001–2016) of catch-effort data were analyzed using two surplus production models (Schaefer and Fox), the Monte Carlo method (CMSY) and the Bayesian state-space Schaefer surplus production model (BSM) method. This research applies a Stock–Production Model Incorporating Covariates (ASPIC) software package to run the Schaefer and Fox model. The maximum sustainable yield (MSY) produced by all models ranged from 33,900 to 35,900 metric tons (mt), which is very close to last year’s catch (33,768 mt in 2016). The estimated B > BMSY and F < FMSY indicated the safe biomass and fishing status. The calculated F/FMSY was 0.89, 0.87, and 0.81, and B/BMSY was 1.05, 1.07, and 1.14 for Fox, Schaefer, and BSM, respectively, indicating the fully exploited status of croaker stock in the BoB, Bangladesh. The representation of the Kobe phase plot suggested that the exploitation of croaker stock started from the yellow (unsustainable) quadrant in 2001 and gradually moved to the green (sustainable) quadrant in 2016 because of the reduction in fishing efforts and safe fishing pressure after 2012. Thus, this research suggests that the current fishing pressure needs to be maintained so that the yearly catch does not exceed the MSY limit of croaker. Additionally, specific management measures should implement to guarantee croaker and other fisheries from the BoB.

scholarly journals Environmental influences on commercial oceanic ommastrephid squids: a stock assessment perspective

2017 ◽  
Vol 81 (1) ◽  
pp. 37 ◽  
Author(s):  
Jintao Wang ◽  
Xinjun Chen ◽  
Kisei Tanaka ◽  
Jie Cao ◽  
Yong Chen
Keyword(s):  
Environmental Variability ◽  
Mean Squared Error ◽  
Stock Assessment ◽  
Reference Points ◽  
Assessment Model ◽  
Production Model ◽  
Northwest Pacific ◽  
Dosidicus Gigas ◽  
Southwest Atlantic ◽  
Data Assessment

Ommastrephid squids are short-lived ecological opportunists and their recruitment is largely driven by the surrounding environment. While recent studies suggest that recruitment variability in several squid species can be partially explained by environmental variability derived from synoptic oceanographic data, assessment of ommastrephid stocks using environmental variability is rare. In thisstudy, we modified asurplus production model to incorporate environmental variability into the assessment of threeommastrephid squids (Ommastrephes bartramii in the northwest Pacific, Illex argentinus in the southwest Atlantic and Dosidicus gigas in the southwest Pacific). We assumed that the key environmental variables—suitable sea surface temperature on spawning grounds during the spawning seasons and feeding grounds during the feeding seasons—have effects on the carrying capacity and the instantaneous population growth rate, respectively, in the surplus production model. For each squid stock, the assessment model with environmental variability had the highest fitting accuracy and the lowest mean squared error and coefficient of variation, and the management reference points based on the optimal model were more precautionary. This study advances our understanding of the interactions between the environment and ommastrephid squid population dynamics and can therefore improve the management of these commercially valuable stocks with a short life cycle.

Stock dynamics and predator–prey effects of Atlantic bonito and bluefish as top predators in the Black Sea

2020 ◽  
Author(s):  
Georgi M Daskalov ◽  
Nazli Demirel ◽  
Aylin Ulman ◽  
Yoana Georgieva ◽  
Mustafa Zengin
Keyword(s):  
Black Sea ◽  
Prey Species ◽  
Maximum Sustainable Yield ◽  
Ecological Impacts ◽  
Reference Points ◽  
Production Model ◽  
Horse Mackerel ◽  
The Black Sea ◽  
Commercial Catch ◽  
General Decline

Abstract This study uses surplus production model-based methods to assess data-poor stocks and estimate key reference points for Atlantic bonito (Sarda sarda) and bluefish (Pomatomus saltatrix) in the Black Sea. Our results demonstrate that the catch maximum sustainable yield (CMSY) method, using catch data only, yields similar results to the more accurate Bayesian Schaefer model (BSM) method, fitted with commercial catch-per-unit-of-effort data, and therefore is suitable in assessing data-poor stocks. We explore the ecological impacts of the two stocks on other commercial species and compare impacts of predation and fishing. Prior to 1995, the consumption of bonito and bluefish on anchovy, horse mackerel, and sprat exceeded the removal of those prey species by the fisheries. Later on, the trends reversed, with catches of prey species becoming more than three times higher than their predation by bonito and bluefish. Horse mackerel, the main prey of bluefish, has declined to critical levels since 1995, which is likely contributing to the general decline in bluefish, along with overfishing. Heavy fishing of bonito and bluefish has caused their current depleted states and combined with their significant impact on prey fish contributed to the ecosystem regime shift in the Black Sea. Due to the present steady positioning of low stock regimes, the recovery of the two stocks need decisive and possibly prolonged rebuilding measures, including a reduction in fishing pressure, efficient control of under-sized catch, and ensuring sufficient prey biomass availability.

scholarly journals Evaluation of the robustness of maximum sustainable yield based management strategies to variations in carrying capacity or migration pattern of Atlantic bluefin tuna (Thunnus thynnus)

2007 ◽  
Vol 64 (5) ◽  
pp. 837-847 ◽  
Author(s):  
Laurence T Kell ◽  
Jean-Marc Fromentin
Keyword(s):  
Carrying Capacity ◽  
Management Strategy ◽  
Stock Assessment ◽  
Management Strategies ◽  
Maximum Sustainable Yield ◽  
Reference Points ◽  
Sustainable Yield ◽  
Size Limit ◽  
Atlantic Bluefin Tuna ◽  
Spawning Stock

In this study, we examine the performances of current stock assessment methods with respect to their ability to (i) provide estimates of maximum sustainable yield (MSY), FMSY, and BMSY and (ii) assess stock status and exploitation level relative to MSY targets. The robustness of the current International Commission for the Conservation of Atlantic Tunas (ICCAT) management strategy is then evaluated with respect to uncertainty about the true population dynamics and contrasted with a simpler management strategy based solely on a size limit. Reference points are more robust to dynamic uncertainty than the estimates of absolute values and trends in F and spawning stock biomass. However, their performances depend on the underlying dynamics (they perform better when fluctuations come from changes in the carrying capacity than migration) and on when they are implemented relative to the intrinsic cycle of the population. Reference points based on F were less biased and more precise than those based on biomass and (or) yield. Although F0.1 appeared to be the best proxy for FMSY, it cannot indicate past and current levels of exploitation relative to FMSY when there is uncertainty about the dynamics. Finally, the F0.1 management strategy of ICCAT performed only slightly better than a simpler strategy based on size limit and led to lower catch levels.

Spawning biomass reference points for exploited marine fishes, incorporating taxonomic and body size information

2012 ◽  
Vol 69 (9) ◽  
pp. 1556-1568 ◽  
Author(s):  
James T. Thorson ◽  
Jason M. Cope ◽  
Trevor A. Branch ◽  
Olaf P. Jensen
Keyword(s):  
Stock Assessment ◽  
Random Effect ◽  
State Space Model ◽  
Maximum Sustainable Yield ◽  
Marine Fishes ◽  
Reference Points ◽  
Data Set ◽  
Sustainable Fishery ◽  
Spawning Biomass ◽  
Taxonomic Order

Surplus production represents the processes that affect sustainable fishery harvest and is central to the ecology and management of marine fishes. Taxonomy and life history influence the ratio of spawning biomass at maximum sustainable yield to average unfished spawning biomass (SBMSY/SB0), and estimating this ratio for individual stocks is notoriously difficult. We use a database of published landings data and stock assessment biomass estimates and determine that process errors predominate in this data set by fitting a state–space model to data from each stock individually. We then fit multispecies process-error models while treating SBMSY/SB0as a random effect that varies by taxonomic order and maximum length. The estimated SBMSY/SB0 = 0.40 for all 147 stocks is intermediate between the values assumed by the Fox and the Schaefer models, although Clupeiformes and Perciformes have lower and Gadiformes and Scorpaeniformes have higher SBMSY/SB0values. Model selection supports the hypothesis that large-bodied fishes for a given taxonomic order have relatively higher SBMSY/SB0. Results can be used to define reference points for data-poor fisheries or as input in emerging assessment methods.

scholarly journals Application of Surplus Production Model to the Yellowfin Tuna Thunnus albacares in the northern and western parts of Aceh waters

2021 ◽  
Vol 869 (1) ◽  
pp. 012072
Author(s):  
A Rahmah ◽  
I Mardhatillah ◽  
A Damora ◽  
M Muhammad ◽  
N Nurfadillah
Keyword(s):  
Economic Value ◽  
Maximum Sustainable Yield ◽  
Yellowfin Tuna ◽  
Production Model ◽  
Purse Seine ◽  
Thunnus Albacares ◽  
Catch Per Unit Effort ◽  
Surplus Production ◽  
Surplus Production Model ◽  
Banda Aceh

Abstract Yellowfin tuna Thunnus albacares is one of pelagic fish that has high potential and economic value in Banda Aceh. Utilization of this resource in Banda Aceh is using purse seine units, with the number of purse seines continuously increasing. Therefore, management needs to be done so that optimal productivity can be maintained. This study discusses the estimation of catch and effort at maximum sustainable yield (MSY) of yellowfin tuna based on catch per unit effort (CPUE) and purse seine production in Banda Aceh during 2013-2018. Mathematical analysis was carried out using the equilibrium approach with the Schaefer model. The highest catch of yellowfin tuna reached 191 tons (July) and the average CPUE for yellowfin tuna was 0.796 tons/trip with CMSY of 2,482 tons/year and EMSY of 2,765 trips/year. From 2015 to 2018, the trend of biomass continued to decline and overfishing occurred during this period.

scholarly journals Evidence of overfishing of geoduck clam Panopea globosa from a length-based stock assessment approach

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9069
Author(s):  
Marlene A. Luquin-Covarrubias ◽  
Enrique Morales-Bojórquez ◽  
Juan A. García-Borbón ◽  
Sergio Amezcua-Castro ◽  
Sergio A. Pérez-Valencia ◽  
...  
Keyword(s):  
Stock Assessment ◽  
Growth Patterns ◽  
Reference Points ◽  
Assessment Model ◽  
Individual Growth ◽  
Biological Traits ◽  
Total Biomass ◽  
Fishing Mortality ◽  
Harvest Rate ◽  
Assessment Approach

Stock assessment of the geoduck clam Panopea globosa in Mexico has been based on data-poor without consideration of the biological traits of the species, promoting a passive management strategy without biological reference points for its harvest and conservation, which results in limited advice regarding the sustainability of the fishery. The stock assessment was supported on an integrated catch-at-size assessment model. The model described the population changes, including recruitment, selectivity, fishing mortality, individual growth patterns and survival over time, providing management quantities for the geoduck clam fishery, such as biomass-at-length (total and vulnerable) and harvest rate-at-length. The results indicated overfishing of the geoduck clam population; the harvest rate exceeded the management tactics established for this fishery, even the individuals smaller than the minimum legal size (130 mm) were harvested. Thus, declines in the total biomass (from 3,262 to 1,130 t) and recruitment (representing an 86% decrease) were observed from 2010 to 2012. Although the results showed a recovery trend in recruitment and total biomass from 2014 to 2016, this trend may have been due to the spatial relocation of fishing mortality.

scholarly journals Bioeconomics of Commercial Marine Fisheries of Bay of Bengal: Status and Direction

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Ahasan Habib ◽  
Md. Hadayet Ullah ◽  
Nguyen Ngoc Duy
Keyword(s):  
Bay Of Bengal ◽  
Legal Framework ◽  
Fishing Effort ◽  
Maximum Sustainable Yield ◽  
Reference Points ◽  
Production Model ◽  
Marine Fishery ◽  
Maximum Economic Yield ◽  
Surplus Production Model ◽  
Marine Realm

The fishery of the Bay of Bengal (BOB) is assumed to be suffering from the overexploitation. This paper aims to assess the sustainability of current level of fishing effort as well as possible changes driven by anthropogenic and climate driven factors. Therefore, the commercial marine fishery of BOB for the period of 1985/86 to 2007/08 is analyzed by applying Gordon-Schaefer Surplus Production Model on time series of total catch and standardized effort. Static reference points such as open-access equilibrium, maximum economic yield, and maximum sustainable yield are established. Assumptions about potential climatic and anthropogenic effects on r (intrinsic growth rate) and K (carrying capacity) of BOB fishery have been made under three different reference equilibriums. The results showed that the fishery is not biologically overexploited; however, it is predicted to be passing a critical situation, in terms of achieving reference points in the near future. But, on the other hand, economic overfishing started several years before. Higher fishing effort, and inadequate institutional and legal framework have been the major bottlenecks for the proper management of BOB fisheries and these may leads fishery more vulnerable against changing marine realm. Thus, the present study calls for policy intervention to rescue the stock from the existing high fishing pressure that would lead to depletion.

An age-structured model with leading management parameters, incorporating age-specific selectivity and maturity

2008 ◽  
Vol 65 (2) ◽  
pp. 286-296 ◽  
Author(s):  
Robyn E Forrest ◽  
Steven J.D. Martell ◽  
Michael C Melnychuk ◽  
Carl J Walters
Keyword(s):  
Life History Traits ◽  
Stock Assessment ◽  
Maximum Sustainable Yield ◽  
Reference Points ◽  
Fish Stock ◽  
Structured Model ◽  
Specific Selectivity ◽  
Stock Recruitment ◽  
Age Structured ◽  
Age Structured Model

Previous authors have shown analytically that the optimal equilibrium harvest rate (UMSY) for an iteroparous fish stock is a function of the slope of the stock-recruitment curve at low stock size (α) and that UMSY can therefore be considered a direct measure of stock productivity. As such, it can be used as a leading parameter in stock assessment models and directly estimated using Bayesian or similar techniques. Here we present an alternative method for deriving α from UMSY that incorporates age-specific selectivity and fecundity, avoiding assumptions of knife-edged recruitment and maturity. We present an age-structured model with two fisheries reference points (UMSY and maximum sustainable yield, MSY) as its leading parameters. We show equilibrium properties of the model, chiefly in terms of its ability to show relationships between life history traits, density dependence, and UMSY. We also demonstrate a simple Bayesian estimation routine to illustrate estimation of UMSY and MSY directly from data. We compare our results to those from a structurally identical model with leading biological parameters. Using models with leading management parameters can improve communicability of results to managers.

Sign in / Sign up

Export Citation Format

Share Document