scholarly journals The estimation of potential yield and stock status using life–history parameters

2005 ◽  
Vol 360 (1453) ◽  
pp. 163-170 ◽  
Author(s):  
J. R. Beddington ◽  
G. P. Kirkwood
Keyword(s):  
Life History ◽  
Growth Parameters ◽  
Maximum Yield ◽  
Maximum Sustainable Yield ◽  
Sustainable Yield ◽  
Fishing Mortality ◽  
Potential Yield ◽  
Stock Status ◽  
Fishing Capacity ◽  
Stock Recruitment

Using life–history invariants, this paper develops techniques that allow the estimation of maximum sustainable yield and the fishing mortality rate that produces the maximum yield from estimates of the growth parameters, the length at first capture and the steepness of the stock recruitment relationship. This allows sustainable yields and fishing capacity to be estimated from sparse data, such as those available for developing country fisheries.

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.

scholarly journals Delay in fishery management: diminished yield, longer rebuilding, and increased probability of stock collapse1

2006 ◽  
Vol 64 (1) ◽  
pp. 149-159 ◽  
Author(s):  
Kyle W. Shertzer ◽  
Michael H. Prager
Keyword(s):  
Fishery Management ◽  
Economic Loss ◽  
Maximum Sustainable Yield ◽  
Sustainable Yield ◽  
Short Term ◽  
Stock Status ◽  
Stock Biomass ◽  
Spawning Stock ◽  
Stock Recruitment ◽  
Stock Collapse

Abstract Shertzer, K. W., and Prager, M. H. 2007. Delay in fishery management: diminished yield, longer rebuilding, and increased probability of stock collapse. ICES Journal of Marine Science, 64: 149–159. When a stock is depleted, catch reductions are in order, but typically they are implemented only after considerable delay. Delay occurs because fishery management is political, and stricter management, which involves short-term economic loss, is unpopular. Informed of stock decline, managers often hesitate, perhaps pondering the uncertainty of scientific advice, perhaps hoping that a good year class will render action moot. However, management delay itself can have significant costs, when it exacerbates stock decline. To examine the biological consequences of delay, we simulated a spectrum of fisheries under various degrees of delay in management. Increased delay required larger catch reductions, for more years, to recover benchmark stock status (here, spawning-stock biomass at maximum sustainable yield). Management delay caused stock collapse most often under two conditions: (1) when the stock–recruitment relationship was depensatory, or (2) when catchability, unknown to the assessment, was density-dependent and fishing took juveniles. In contrast, prompt management resulted in quicker recoveries and higher cumulative yields from simulated fisheries. Benefits to stock biomass and fishery yield can be high from implementing management promptly.

scholarly journals Growth, Mortality And Yield Per Recruit Of Bogue, Boops Boops (L.), From The Egyptian Mediterranean Waters Off Alexandria

2003 ◽  
Vol 4 (1) ◽  
pp. 87 ◽  
Author(s):  
S.M. ALLAM
Keyword(s):  
Growth Parameters ◽  
Maximum Yield ◽  
Total Mortality ◽  
Age And Growth ◽  
Fishing Mortality ◽  
Potential Yield ◽  
Significant Difference ◽  
Annulus Formation ◽  
Yield Per Recruit ◽  
Boops Boops

Age and growth of Boops boops(L.) from the Mediterranean Sea off Alexandria were estimated from scales. No significant difference in growth was found between male and female. Back-calculated lengths at annulus formation for combined sex were 10.97, 14.03, 16.39, 18.56 and 20.51cm TL. The estimated von Bertalanffy growth parameters were L ‡ = 31.68 cm, K = 0.1531 year -1 and t Ζ = -1.7838.The length-weight relationship was W = -2.1548L 3.1031 . Total mortality (Z), natural mortality (M) and fishing mortality (F) were 1.283, 0.458 and 0.824 year -1 respectively. The exploitation rate (E) was 0.464. A Beverton-Holt yieldper- recruit model indicated that the maximum yield-per-recruit was 21.06 g when fishing mortality was 2.4 and the current fishery harvests approximately 95% of the potential yield.

scholarly journals The status of Japanese fisheries relative to fisheries around the world

2017 ◽  
Vol 74 (5) ◽  
pp. 1277-1287 ◽  
Author(s):  
Momoko Ichinokawa ◽  
Hiroshi Okamura ◽  
Hiroyuki Kurota
Keyword(s):  
Maximum Sustainable Yield ◽  
Production Model ◽  
Structured Population Model ◽  
Total Allowable Catch ◽  
Quick Recovery ◽  
Stock Status ◽  
Surplus Production Model ◽  
The Status ◽  
Stock Recruitment ◽  
Age Structured

We present the first quantitative review of the stock status relative to the stock biomass (B) and the exploitation rate (U) that achieved the maximum sustainable yield (MSY) (BMSY and UMSY, respectively) for 37 Japanese stocks contributing 61% of the total marine capture production in Japan. BMSY and UMSY were estimated by assuming three types of stock-recruitment (S-R) relationships and an age-structured population model or by applying a surplus production model. The estimated stock status shows that approximately half of the stocks were overfishing (U/UMSY > 1), and approximately half of the stocks were overfished (B/BMSY < 0.5) during 2011–2013. Over the past 15 years, U decreased and B slightly increased on average. The rate of decrease in the U of the stocks managed by the total allowable catch (TAC) was significantly greater than that of the other stocks, providing evidence of the effectiveness of TAC management in Japan. The above statuses and trends were insensitive to the assumption of the S-R relationship. The characteristics of Japanese stocks composed mainly of resources with relatively high natural mortality, i.e. productivity, suggest that Japanese fisheries have great potential of exhibiting a quick recovery and increasing their yield by adjusting the fishing intensity to an appropriate level.

Spatial variation in fishing intensity and its effect on yield

2008 ◽  
Vol 65 (4) ◽  
pp. 588-599 ◽  
Author(s):  
Stephen Ralston ◽  
Michael R O’Farrell
Keyword(s):  
Spatial Variation ◽  
Local Density ◽  
Life Stage ◽  
Maximum Sustainable Yield ◽  
Recruitment Rate ◽  
Sustainable Yield ◽  
Fishing Mortality ◽  
Density Dependent ◽  
Age Structured ◽  
Effect On Yield

Fishing mortality is rarely, if ever, evenly distributed over space, yet this is a common assumption of many fisheries models. To evaluate the effect of spatial heterogeneity in fishing mortality on yield, we constructed age-structured models that allowed for differing levels of fishing in three regions within the boundaries of a stock and explored alternative assumptions about the life stage in which density-dependent compensation operates. If the fishing mortality rate (F) is not excessive (i.e., F ≤ FMSY defined for the spatially homogeneous case; MSY, maximum sustainable yield), simulations demonstrated that minor to moderate spatial variation in fishing intensity does not impact sustainable yield. However, if fishing mortality is excessive (F > FMSY), spatial variation in fishing intensity often improves yield and can actually produce yields in excess of MSY when compensation occurs after dispersal, and the density-dependent recruitment rate is a function of the local density of adults. The yield premium generated in these simulations by postdispersal density dependence is due to a low level of compensatory mortality in heavily fished areas coupled with dispersal of propagules into these areas from lightly fished adjacent regions.

Population dynamics and stock assessment of Hilsa shad, Tenualosa ilisha (Hamilton, 1822) along the coast of Bangladesh

2021 ◽  
Vol 48 (2) ◽  
pp. 231-241
Author(s):  
Md Khairul Islam ◽  
Md Humayun ◽  
Manmatha Nath Sarker ◽  
Md Sharifuddin ◽  
M Niamul Naser
Keyword(s):  
Growth Parameters ◽  
Stock Assessment ◽  
Population Analysis ◽  
Total Mortality ◽  
Maximum Sustainable Yield ◽  
Fishing Mortality ◽  
Recruitment Pattern ◽  
Weight Relationship ◽  
Tenualosa Ilisha ◽  
Highly Correlated

Stock Assessment of Tenualosa ilisha (Hamilton, 1822) were estimated using FiSAT-II software with length-frequency data collected from different landing centers. The Southeast Coast of Bay Of Bengal, Cox's Bazar. The Von Bertalanffy growth parameters Land K for the species were asymptotic length (L∞) was 51.41 cm, growth rate (K) was 0.75 year-1 and t0 = -0.2 year respectively. The estimated value of total mortality (Z) based on length converted catch curve using these growth parameters was 2.35 year-1.Natural mortality (M) based on growth parameters and mean environmental temperature (T = 27° C) was 1.00 year-1 and fishing mortality (F) was 1.35 year-1. Optimum length of hilsa at first capture (Lc=L50) was 28.36 cm TL. Growth performance indices (ϕ') was 3.30. The estimated value of the exploitation rate (E) using the length-converted catch curve was 0.57. The recruitment pattern of this species was continuous and two peaks per year. The present investigation clearly showed the over fishing (E > 0.50) condition for T. ilisha in Bangladesh. The estimated length-weight relationship for the combined sex was found to be W = 0.0109 L3. Virtual population analysis (VPA) showed that the maximum fishing mortality occurring in the length between 30 to 35 cm with a maximum value in the length of 32 cm that repeatedly indicate high fishing mortality in the T. ilisha. The generalized length-weight relationship was fitted with the pooled data of all monthly samples were BW = 0.029 TL2.718 (R2= 0.833) respectively. The results revealed that all length-weight relationships were highly correlated (r > 0.993). Maximum sustainable yield (MSY) was estimated as 435,554 t. Bangladesh J. Zool. 48(2): 231-241, 2020

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.

Relationship of Fishing Mortality to Natural Mortality and Growth at the Level of Maximum Sustainable Yield

1982 ◽  
Vol 39 (7) ◽  
pp. 1054-1058 ◽  
Author(s):  
R. B. Deriso
Keyword(s):  
Logistic Model ◽  
Mortality Rates ◽  
Maximum Sustainable Yield ◽  
Sustainable Yield ◽  
Natural Mortality ◽  
Fishing Mortality ◽  
Difference Model ◽  
Relationship Of ◽  
Yield Per Recruit ◽  
Delay Difference

Fishing mortality constraints are derived for fishes harvested at the maximum sustainable yield (MSY) determined by a delay-difference population model. Those constraints depend upon rates of natural mortality and growth as well as a simple constraint placed on abundance of the exploited population. The results are generalized for a wider class of population models where it is shown that MSY fishing mortality is constrained often to be less than the fishing mortality which maximizes yield per recruit. Fishing mortality rates are lower in the delay difference model in comparison to MSY fishing rates in the logistic model, when a quadratic spawner–recruit curve is applied.Key words: delay-difference model, logistic model, fishing mortality, maximum sustainable yield, yield per recruit

Optimal F0.1 Criteria and Their Relationship to Maximum Sustainable Yield

1987 ◽  
Vol 44 (S2) ◽  
pp. s339-s348 ◽  
Author(s):  
R. B. Deriso
Keyword(s):  
Quantitative Relationship ◽  
Maximum Sustainable Yield ◽  
Sustainable Yield ◽  
Fish Stocks ◽  
Pacific Halibut ◽  
Western Lake ◽  
Gadus Macrocephalus ◽  
Hippoglossus Stenolepis ◽  
Stock Recruitment ◽  
Yield Per Recruit

There is a unique size of entry into the fishable population that maximizes yield per recruit when an F0.1 fishing criterion is applied to the simple theory of fishing developed by Beverton and Holt in 1957. I define such a pair of parameters (size of entry, F0.1 value) to be the optimal F0.1 criteria and show that they are characterized by the single quantity M/K. A quantitative relationship is established between maximum sustainable yield and the optimal F0.1 criteria for a model population where recruitment is governed by a Ricker stock–recruitment function. This new theory is applied to three fish stocks: Pacific halibut (Hippoglossus stenolepis), western Lake Erie walleye (Stizostedion vitreum vitreum), and Bering Sea Pacific cod (Gadus macrocephalus).

scholarly journals Will depleted populations of Pacific salmon recover under persistent reductions in survival and catastrophic mortality events?

2010 ◽  
Vol 67 (9) ◽  
pp. 2018-2026 ◽  
Author(s):  
Carrie A. Holt
Keyword(s):  
Pacific Salmon ◽  
Survival Rates ◽  
Simulation Models ◽  
Time Frame ◽  
Maximum Sustainable Yield ◽  
Sustainable Yield ◽  
Fishing Mortality ◽  
Replacement Level ◽  
Case Examples ◽  
Green Zone

Abstract Holt, C. A. 2010. Will depleted populations of Pacific salmon recover under persistent reductions in survival and catastrophic mortality events? – ICES Journal of Marine Science, 67: 2018–2026. Under Canada's Wild Salmon Policy, benchmarks between zones of biological status are required to distinguish populations requiring conservation attention (Red and Amber zones) from those that can be managed for production (Green zone). The recovery of depleted populations (i.e. from Red to Green) will depend in part on the choice of the lower benchmark. At a minimum, that benchmark should be set high enough to allow recovery within an acceptable time-frame in the absence of targeted fishing. Currently, benchmarks are evaluated and selected using simulation models that assess the probability of recovery to spawner abundance associated with the maximum sustainable yield within a specified time-frame. Guided by case examples, the evaluation is extended to include two scenarios of future conditions: persistent reductions in survival rates below the replacement level; and increased frequency of catastrophic mortality (die-off) events. Probabilities of recovery appear to be more sensitive to persistent reductions in survival than to increased probability of die-off events. The current lower benchmarks on spawner abundance and fishing mortality might not be sufficiently precautionary to allow recovery under those conditions.

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