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.

scholarly journals Evaluating management strategies to implement the recovery plan for Iberian hake (Merluccius merluccius); the impact of censored catch information

2009 ◽  
Vol 67 (2) ◽  
pp. 258-269 ◽  
Author(s):  
Ernesto Jardim ◽  
Santiago Cerviño ◽  
Manuela Azevedo
Keyword(s):  
Management Strategies ◽  
Maximum Sustainable Yield ◽  
Sustainable Yield ◽  
Fishing Mortality ◽  
Merluccius Merluccius ◽  
Total Allowable Catch ◽  
Recovery Plan ◽  
Stock Biomass ◽  
Spawning Stock ◽  
The Impact

Abstract Jardim, E., Cerviño, S., and Azevedo, M. 2010. Evaluating management strategies to implement the recovery plan for Iberian hake (Merluccius merluccius); the impact of censored catch information. – ICES Journal of Marine Science, 67: 258–269. Iberian hake assessment revealed an increase in fishing mortality (F) despite enforcement of a recovery plan. Recent landings exceeded the total allowable catch and discarding rates were high. Alternative management strategies based on F control were evaluated with respect to the probability of recovering spawning-stock biomass (SSB), expected profits, and robustness to uncertainty on catch information and stock dynamics. Results showed that the use of censored catch data, i.e. excluding the Gulf of Cádiz or discards, may lead to inappropriate conclusions. Reducing fishing mortality was necessary for SSB to recover. An Fmax strategy with discard reduction showed the highest probability of rebuilding SSB and led the fishery to sustainable exploitation, with an expected %SPR of 30–40% in 2025, mean individual weight in the landings of 450 g in 2015, and yield increasing by >20%. Because of uncertainty in the estimates of maximum sustainable yield, management strategies based on FMSY were least robust, but all strategies were robust to alternative stock–recruit models.

scholarly journals A continuous hockey stick stock–recruit model for estimating MSY reference points

2010 ◽  
Vol 67 (8) ◽  
pp. 1780-1784 ◽  
Author(s):  
Benoit Mesnil ◽  
Marie-Joëlle Rochet
Keyword(s):  
Stock Assessment ◽  
Maximum Sustainable Yield ◽  
Reference Points ◽  
Sustainable Yield ◽  
Political Commitment ◽  
Hockey Stick ◽  
Differentiable Functions ◽  
Piecewise Function ◽  
Management Plans ◽  
Stock Recruitment

Abstract Mesnil, B., and Rochet, M-J. 2010. A continuous hockey stick stock–recruit model for estimating MSY reference points. – ICES Journal of Marine Science, 67: 1780–1784. With political commitment to restore stocks to levels where they can produce maximum sustainable yield (MSY), fisheries managers request evaluation of management plans that include options for an FMSY policy. The procedure to estimate FMSY with dynamic-pool, stock assessment models is well established for common stock–recruitment relationships (S–RR), and this capacity is extended to another S–RR, a piecewise function known as the hockey stick (HS), which is frequently assumed when the data do not support more elaborate functions. However, the HS is not continuous, which makes it problematic for this application, where differentiable functions are required. The bent-hyperbola model proves to be an adequate continuous equivalent to the HS for estimating FMSY.

scholarly journals Stock Assessment: Sustainable management in high and medium Araguari River, Amapá, Brazil.

2020 ◽  
Vol 42 ◽  
pp. e71
Author(s):  
Luiza Prestes ◽  
Fabiana Calacina da Cunha ◽  
Maria Gercilia Mota Soares ◽  
Marcos Sidney Brito Oliveira ◽  
Netie Izabel Oliveira ◽  
...  
Keyword(s):  
Natural Resources ◽  
Sustainable Management ◽  
Stock Assessment ◽  
Maximum Sustainable Yield ◽  
Reference Points ◽  
Sustainable Yield ◽  
Maximum Economic Yield ◽  
The Status ◽  
Future Management

Fisheries in Araguari river is an alternative income for families that depend on exploitation of natural resources. This study evaluates fisheries production in high and medium Araguari river to determine the bioeconomic reference points of fishery activities. Logbooks of fisheries were used from Fishermen Colony Z-16 from 2003 to 2010. The Maximum Sustainable Yield (MSY) and Effort at Maximum Sustainable Yield (fmsy) was: MSYSchaefer = 11246 kg and fmsy = 754 fisheries/year, and MSYFox = 11478 kg and fmsy = 1214 fisheries/year and at Bioeconomic Equilibrium (Eebe) Eebe = 10712 kg and Effort at Bioeconomic Equilibrium (febe) febe = 918 fisheries/year. The status of fisheries from Araguari River was declared as overfishing and in this study, we found the same results. The Maximum Economic Yield (MEY) was reached too, as the fisheries were at Bioeconomic Equilibrium (EBE). The fishery mortality (Fyear/Fmsy) and fishery effort (fyear/fmsy) trends show that from 2003 to 2009 the values were sustainable. In 2010 those trends became unsustainable, and the Maximum Economic Yield (MEY) for all years is unsustainable too. It is required this study be considered in future management agreements.

scholarly journals Can stock–recruitment points determine which spawning potential ratio is the best proxy for maximum sustainable yield reference points?

2013 ◽  
Vol 70 (6) ◽  
pp. 1075-1080 ◽  
Author(s):  
Christopher M. Legault ◽  
Elizabeth N. Brooks
Keyword(s):  
Life History ◽  
Mortality Rate ◽  
Maximum Sustainable Yield ◽  
Reference Points ◽  
Sustainable Yield ◽  
Marine Science ◽  
Fishing Mortality ◽  
Scatter Plots ◽  
Stock Recruitment ◽  
Spawning Potential Ratio

Abstract Legault, C. M., and Brooks, E. N. 2013. Can stock–recruitment points determine which spawning potential ratio is the best proxy for maximum sustainable yield reference points? – ICES Journal of Marine Science, 70: 1075–1080. The approach of examining scatter plots of stock–recruitment (S–R) estimates to determine appropriate spawning potential ratio (SPR)-based proxies for FMSY was investigated through simulation. As originally proposed, the approach assumed that points above a replacement line indicate year classes that produced a surplus of spawners, while points below that line failed to achieve replacement. In practice, this has been implemented by determining Fmed, the fishing mortality rate that produces a replacement line with 50% of the points above and 50% below the line. A new variation on this approach suggests FMSY proxies can be determined by examining the distribution of S–R points that are above or below replacement lines associated with specific SPRs. Through both analytical calculations and stochastic results, we demonstrate that this approach is fundamentally flawed and that in some cases the inference is diametrically opposed to the method's intended purpose. We reject this approach as a tool for determining FMSY proxies. We recommend that the current proxy of F40% be maintained as appropriate for a typical groundfish life history.

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 An explicit solution for calculating optimum spawning stock size from Ricker’s stock recruitment model

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e1623 ◽  
Author(s):  
Mark D. Scheuerell
Keyword(s):  
Explicit Solution ◽  
Model Fitting ◽  
Maximum Sustainable Yield ◽  
Reference Points ◽  
Stock Size ◽  
Points Of Interest ◽  
Spawning Stock ◽  
Stock Recruitment ◽  
Explicit Formulae ◽  
Recruitment Model

Stock-recruitment models have been used for decades in fisheries management as a means of formalizing the expected number of offspring that recruit to a fishery based on the number of parents. In particular, Ricker’s stock recruitment model is widely used due to its flexibility and ease with which the parameters can be estimated. After model fitting, the spawning stock size that produces the maximum sustainable yield (SMSY) to a fishery, and the harvest corresponding to it (UMSY), are two of the most common biological reference points of interest to fisheries managers. However, to date there has been no explicit solution for either reference point because of the transcendental nature of the equation needed to solve for them. Therefore, numerical or statistical approximations have been used for more than 30 years. Here I provide explicit formulae for calculating bothSMSYandUMSYin terms of the productivity and density-dependent parameters of Ricker’s model.

Incorporating habitat preference into the stock assessment and management of blue marlin (Makaira nigricans) in the Pacific Ocean

2012 ◽  
Vol 63 (7) ◽  
pp. 565 ◽  
Author(s):  
Nan-Jay Su ◽  
Chi-Lu Sun ◽  
André E. Punt ◽  
Su-Zan Yeh ◽  
Gerard DiNardo
Keyword(s):  
Population Dynamics ◽  
Habitat Preference ◽  
Stock Assessment ◽  
Ecosystem Approach ◽  
Maximum Sustainable Yield ◽  
Blue Marlin ◽  
Makaira Nigricans ◽  
Biological Variables ◽  
Population Dynamics Model ◽  
Spawning Stock

Stock assessments that include a spatial component or relate population dynamics to environmental conditions can be considered one way of implementing an ecosystem approach to fisheries. A spatially-structured population dynamics model that takes account of habitat preference is developed and then applied to Pacific blue marlin (Makaira nigricans), as they prefer certain habitats and migrate seasonally. The model is fitted to fishery catch-rate and size data, along with information on the relative density of the population over space derived from a habitat preference model fitted to oceanographic and biological variables. Results show that blue marlin are more abundant in tropical waters, and females account for most of the biomass. Assessments that allow for environmental factors, movement dynamics and sexual dimorphism indicate that this population is in an over-exploited state, with current spawning stock biomass below the level corresponding to maximum sustainable yield (SMSY) and current fishing mortality exceeding that needed to achieve MSY (FMSY). A risk analysis based on samples from a Bayesian posterior distribution suggests that the population will remain above SMSY after 20 years if exploitation rates are below the level corresponding to FMSY.

Recruitment variation in abalone: Its importance to fisheries management

1995 ◽  
Vol 46 (3) ◽  
pp. 555 ◽  
Author(s):  
PE McShane
Keyword(s):  
Egg Production ◽  
Field Experiments ◽  
Stock Assessment ◽  
Reference Points ◽  
High Fecundity ◽  
Spatial And Temporal Scales ◽  
Recruitment Failure ◽  
Spawning Stock ◽  
Stock Recruitment ◽  
Many Sources

Recruitment failure has been implicated in the decline of several abalone fisheries. Traditionally, fisheries scientists invoke theoretical stock-recruitment relationships to predict trends in abundance of an exploited stock under various harvest regimes. The empirical evidence in support of a positive relationship between spawning stock and recruits is not strong. A further problem in interpretation of such relationships is that both 'stock' and 'recruitment' have various definitions in fisheries and ecological literature. The definition of a stock for abalone is not clear. As emphasized in this review, which considers each stage in the life history of abalone, the abundance of spawners is one of many sources of variation in recruitment. The evidence for invertebrates, particularly those with high fecundity, is that recruitment varies independently of the abundance of spawners. This is also the case for abalone, where recruits have been measured as the density of immediate post-settlement individuals, juveniles, or as adults entering the exploitable stock. A problem with stock-recruitment hypotheses is that they have intuitive appeal. It is considered 'dangerous' to manage fisheries under the assumption that a reduction in the number of spawners by fishing will not affect recruitment. Such danger to abalone stocks has been more recently assessed by egg-per-recruit analyses, whereby various harvest strategies are examined relative to reference points for egg production. These studies are reviewed and assessed relative to the often conflicting aims of managers and scientists. This review of studies of recruitment variation in abalone emphasizes the need for a more rigorous, autecological approach to stock assessment in which field experiments are conducted over realistic spatial and temporal scales, permitting robust testing of hypotheses.

scholarly journals The monkfish fishery and its management in the northeastern USA

2008 ◽  
Vol 65 (7) ◽  
pp. 1370-1379 ◽  
Author(s):  
Phil Haring ◽  
J-J. Maguire
Keyword(s):  
Fishery Management ◽  
Management Plan ◽  
Maximum Sustainable Yield ◽  
Reference Points ◽  
Sustainable Yield ◽  
Marine Science ◽  
The Us ◽  
Management Plans ◽  
Northeastern Usa ◽  
Innovative Approaches

Abstract Haring, P., and Maguire, J-J. 2008. The monkfish fishery and its management in the northeastern USA. – ICES Journal of Marine Science, 65: 1370–1379. The domestic monkfish (Lophius americanus) fishery off the northeastern USA is described, along with the management response to the expansion of the fishery and the challenges posed to the management and scientific processes. The US fishery was virtually non-existent in the early 1980s, but it expanded rapidly over the next decade to the point that a management plan became necessary to regulate harvesting. By law, US fishery management plans must include measurable biological reference points based on maximum sustainable yield or a proxy; management plans must stop overfishing and rebuild overfished stocks. For monkfish, the limited biological and historical fisheries information presented significant challenges to science and management and resulted in the adoption of innovative approaches to comply with the law.

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