Maximum Sustainable Yield Values Research Articles

Assessment of Three Major Shrimp Stocks in Bangladesh Marine Waters Using Both Length-Based and Catch-Based Approaches

Penaeus monodon (tiger shrimp), Metapenaeus monoceros (brown shrimp), and Fenneropenaeus indicus (white shrimp) are the most economically important shrimp species in the waters of the Bay of Bengal, Bangladesh. This is the first analytical study to assess three major shrimp stocks using both length-based and catch-based methods, such as length-based Bayesian biomass estimation (LBB), length-based indicator (LBI), and a catch-based method entitled JABBA (Just Another Bayesian Biomass Assessment), to explore and process the data; estimate the growth parameters, with length at first capture; present relative biomasses; and approximate the reference points. The parameters of the von Bertalanffy Growth Function (VBGF) analysis for the tiger, brown, and white shrimps were L∞ = 113.0 mm, 85.4 mm, and 76.4 mm, respectively, for carapace length. Our results showed that the relative biomass level (B/BMSY) of the tiger shrimp was 0.43, suggesting an overfished status, and brown and white shrimps were 0.84 and 0.96, indicating that they were fully exploited but not overfished. This study, therefore, advised an optimum carapace length limit to catch from 57.0–70.0 mm for tiger shrimp, 44.0–53.0 mm for brown shrimp, and 40.0–48.0 mm for white shrimp. The estimated maximum sustainable yield (MSY) reference points were as follows: optimal biomass BMSY = 3116 mt, 15,885 mt, and 2649 mt for tiger, brown, and white shrimp, respectively, and optimal harvest rate uMSY = 12%, 33%, and 8% for tiger, brown, and white shrimp, respectively. The average annual catch values for the last ten years were 265 mt, 2396 mt, and 115 mt below the estimated MSY values of 389 mt, 4899 mt, and 209 mt for tiger, brown, and white shrimp, respectively. But, brown shrimp had the estimated highest carrying capacity (31,770 mt) and intrinsic growth rate (0.66) than the tiger and white shrimp, which was replicated distinctly in the graphical representation of the Kobe plot and the surplus production plot. Hence, the brown shrimp stock is estimated to be in a better state than the tiger and white shrimp stocks.

Assessment and management recommendations for the status of Japanese sardine Sardinops melanostictus population in the Northwest Pacific

Japanese sardine (Sardinops melanostictus) is one of the main species caught in the high seas purse seine fishery in the Northwest Pacific Ocean and its resources gradually recovered in recent years. This paper used the historical yearly catch data of Japanese sardine from 1990 to 2021 and biological data (manily for body length) in April-November 2020–2022 to assess its maximum sustainable yield (MSY) and stock resource status using Catch-MSY and LBB models, respectively. And then based on the evaluation results of Japanese sardine MSY, we analyzed the stock management strategies on this species by the Kobe II Strategy Matrix (K2SM). The results were as follows: (1) the Catch-MSY model assessed its MSY as 170.0 × 104 t with a 95 % confidence interval of 134.1 × 104 t ∼ 211.4 × 104 t; (2) the LBB model assessed the biological parameters for the last three years (2020–2022) with the interval range of Lc/Lc_opt was 0.76–0.95, B/BMSY was 0.79–0.84, and B/B0 was 1.9–2.3, which indicate that Japanese sardine resource is healthy and recovering; (3) the results of these two models and the Kobe Ⅱ management strategy matrix are combined to predict future resource status probability values. The management target range for the medium term (5-10 years) should be set 100 % TAC to MSY values, i.e., 102.0 × 104 t–170.0 × 104 t as TAC, and for the long term (10–20 years) can be set to 120 % TAC to MSY values, i.e., 122.4 × 104 t–170.0 × 104 t. Japanese sardine fishery resource can be sustainably used on a longer time scale.

Effective Management of Hilsa Shad (Tenualosa ilisha): Prevailing Research Trends in Bangladesh

Aim: The purpose of this review is to support widely accepted knowledge based effective management of Hilsa shad populations through smart decisions.
 Study Design: Literature review of the population dynamics based studies along with the relevant papers of Hilsa shad fishery management in Bangladesh. Thus, accurate estimations of population size, growth parameters, mortalities and exploitation rates are critical for success.
 Place and Duration of Study: The literature review and other relevant documents are based in the coastal and riverine areas of Bangladesh during last three decades.
 Methodology: The review mainly included research findings on the catch and population dynamics of Hilsa shad in the riverine and coastal habitats of Bangladesh. This review comprised of published results on asymptotic length (Lµ), growth co-efficient (K), Growth performance index (ф’), mortality rates (natural-M, fishing-F and total-Z), exploitation rates (E), gear selectivity (Lc), maximum sustainable yield (MSY), standing stock or steady state biomass (SSB), average weight/length and length-weight relationship parameters.
 Results: The asymptotic length, growth co-efficient and growth performance index were varied from 51.5 to 65.6cm, 0.51 to 0.99 and 3.14 to 3.55 respectively. The variation of growth range was appeared from 21.19 – 37.69, 33.66 – 51.69, 41.0 – 56.89, 45.32 – 59.09, 47.86 – 60.79 and 49.36 – 62.52 cm at the end of age 1, 2, 3, 4, 5 and 6 years respectively. Simultaneously, natural, fishing and total mortality were varied from 0.89 to 1.52, 0.45 to 3.45 and 1.68 to 4.9 respectively. The exploitation rates were varied between 0.27 and 0.70, and the length at first capture were differs to be 39.24 to 57.65% of the mean asymptotic length. The overall mean length and weight value equal to 34.0±2.67cm and 540±120gm respectively. While the majority of the research papers (90%) indicated, overfishing, the annual catch of the species shows an increasing trend of 10,038 tons per year (R2=0.81) between financial year 1989-90 and 2018-19. The estimated MSY varied from 162396 to 283597, 283597 to 404798 and 404798 to 526000 tons from 60%, 30% and 10% studies respectively. The mean MSY value equal to 282174 ±100530 tons. Besides, three case studies showed deviations, inclusion of hypothesis based results and analytical gap. Thus, through the continual publication process the absolute unclear results maybe adjust or accepts in the national policy, including SDG-14s.
 Conclusions: The study indicated that the importance of science excellence, precise assessment and accurate estimation of the status of the fish stocks is vital for sustainable management of a fishery. Thus, the technical investigations need experience to analyze, predict results and produce fisheries management related suggestions, which is highly correlated to national or regional resource management decision.

ANALISIS STRATEGI PENGEMBANGAN PERIKANAN RAJUNGAN DI PANTAI PUDING BANGKA SELATAN

The swimming crab is a type of sea crab whose abudance is distributed almost evenly across Indonesian waters. There are aspect that need to be considered in the use of swimming crab resources, namely biological technical, and economical aspect. So, taht it can be done without endangering the sustainability of the resources. The research was conducted from April through July, 2018, in Puding Beach, South Bangka Regency. The primary and secondary data were obtained using 3 method of analysis, namely analysis of maximum sustainable yield (MSY), analysis of utilization rates, business analysis, and SWOT analysis. The result suggested that the MSY value was of 1,319.059 ton/year and the foptimum was 23,877.356 trips/year. This suggests that overfishing has taken place ang that the utilization of swimming crab resources has surpassed the limit of TAC. the fishing gear used by fisherman for catching swimming carbs in Puding Beach is the collapsible trap with the operating principle of one day fishing. Based on business analysis, it was found that the activity is profitable for the fisherman and tah business if feasible. The researchers also formulated 12 alternative strategies for crab meat business development in Puding Beach.

Maximum Sustainable Yield Estimates of Marine Captured Shrimp Fishery of the Bay of Bengal, Bangladesh by Using Surplus Production Model

Surplus-production models (SPMs) are the foremost conventional methodical tool for assessing fish stock when the data comprised of a time series of catches for an exploited population. Annual catch and effort data of 24 years from 1991 to 2014 were analyzed to estimate the Maximum Sustainable Yield (MSY) of marine captured shrimps of Bangladesh by using packages of CEDA and ASPIC. The maximum catch was found 4188 Mt in 1992 and the minimum was 2175 Mt in 2006. In CEDA, the MSY was estimated by using the initial proportion (IP) value of 0.7 because the starting catch was approximately 70% of the maximum catch. The estimated MSY values of Fox and Schaefer from CEDA with two error assumptions were 2527 Mt and 2584 Mt; 2794 Mt and 2655 Mt, respectively. Besides, the estimated MSY results of Fox and Logistic (Schaefer) models from the ASPIC packages were 2472 Mt and 2347 Mt respectively. In conclusion, the estimated MSY values were smaller than the last catch (2733Mt) reveals the overfished stock of marine captured shrimp fishery which needed instant management strategies for sustainability.

Maximum Sustainable Yield (MSY) value in predator-prey model with holling type ii functional response

Maximum Sustainable Yield (MSY) is a management exploitation that aims to maximize the catch but still maintain its sustainability. In this article, the authors try to build a model which have been modified from basic Lotka-Volterra model with addition logistic function to prey population and Holling Type II functional response to predator population as well as harvesting of both population. The equilibrium points and the stabilityvare done here through the linearization. Dynamical simulations are shown to illustrate the dynamics of the two populations. Based on the results of analysis and dynamical simulation, the MSY value can be achieved when the harvesting efforts does not exceed or equal the MSY value.

OVERFISHING AND OVERCAPACITY SMALL SCALE FISHERIES IN SEMARANG CITY

Fisheries in Semarang City are dominated by small-scale fisheries. This is indicated by the use of the largest fishing fleet of 10 gross tons operating near the coast. This study aims to analyze the status of small-scale fisheries in Semarang City for sustainable management. Sustainable management is management that guarantees the availability of natural resources and environmental services for future generations. The study was conducted for three months, namely September-November 2018 in the coastal waters of Semarang City, which was part of the Fisheries Management Region (WPP) 712. The method used in this study is the analysis of time series surplus production, namely data from the catch (ton/year) and the number of fishing gear (unit) within 10 years (2007-2016), to calculate the catch per-unit effort (CPUE), maximum sustainable yield (MSY), optimum effort (fopt), utilization rate (TP) and capacity level (TK). This study was obtained results of a downward trend in CPUE; the existing fishery catch or production in 2016 has exceeded the MSY value is 479 tons/year (Schaefer) and 439.11 tons/year (Fox); utilization rate of more than 100% which is 108-127% (Schaefer) and 118-138% (Fox), so that small-scale fisheries in Semarang City are at the level of over-exploited. Based on the fopt analysis, the number of fishing gear used (fexisting) has exceeded the optimum effort with a fishing capacity exceeding 100%, so that small-scale fisheries in Semarang City have experienced overcapacity.

Assessing recent gradual upsurge of marine captured Hilsa stock (Tenualosa ilisha) in Bangladesh

The anadromous Hilsa shad (Tenualosa ilisha) fishery is the prime single species fishery of Bangladesh that driven by open access system which was selected for this study. Key purpose of this study was to assess the MSY (Maximum Sustainable Yield) in order to review the effectivity of the ongoing management policy of this fishery. For this reason, time series maritime or downstream catch-effort data of the Bay of Bengal were assembled from the Department of Fisheries, Bangladesh. MSY, CPUE and other population parameters were estimated through Surplus Production Models (SPMs) using computer software packages of CEDA, ASPIC and TropFishR. Assessed biological reference points of MSY from the best fitted CEDA package was 282,100 t (R2 = 0.822) for the normal assumptions of the Schaefer and Pella-Tomlinson models. MSY values from the ASPIC packages (324,100 t and 263,500 t; for Fox and Schaefer model) and Schaefer model from TropFishR (345,486t) were larger than the catch in 2017 (278,948 t). The values of F ratio (F/FMSY) for all SPMs were found less than 1 and B ratio (B/BMSY) were greater than 1 that clearly indicate the gradual upsurge of the Hilsa stock. Based on the above findings of BRPs, it also proves the effectivity of the current “Hilsa fishery management action plan” by the authorities.

Potential of sustainable and biological aspect of sting ray (Dasyatis sp.) as catch fisheries status overview in Java Sea

Stingray fish is a demersal fish commodity in Indonesian waters which decreasing in catch. The purpose of this research is to know the potential of sustainable and some aspects of Stingray fish biology by using the Maximum Sustainable Yield (MSY) indicator as the fishing status in Java Sea. Data of catch and effort taken from production data of year 2006-2015 and primary data to know some aspect of biology is taken at TPI port of Cirebon and Tegal Specification data of fish catching tools Pari obtained from fisherman interview. The data of the catch in the analysis using Surplus Production Method (Schaefer) and observed aspects of stingray biology include: sex ratio and distribution of length of Stingray fish. The results showed the MSY value of Stingray fish was 894.275 tons / year and fMSY value of 34.716 ships / year. The sex ratio of male Stingray fish with female Stingray fish is still balanced, which is 1: 1.34 and the size of long frequency entered into the category of immature fish gonad and fish which first ripe gonad, which ranges between length 16-22 cm both male fish or female. Based on the research results can be concluded that Stingray fish catchment in Java sea still in sustainable condition.

A continuous time delay-difference type model (CTDDM) applied to stock assessment of the southern Atlantic albacore Thunnus alalunga

A continuous time delay-diff erence model (CTDDM) has been established that considers continuous time delays of biological processes. The southern Atlantic albacore (Thunnus alalunga) stock is the one of the commercially important tuna population in the marine world. The age structured production model (ASPM) and the surplus production model (SPM) have already been used to assess the albacore stock. However, the ASPM requires detailed biological information and the SPM lacks the biological realism. In this study, we focus on applying a CTDDM to the southern Atlantic albacore (T. alalunga) species, which provides an alternative method to assess this fishery. It is the first time that CTDDM has been provided for assessing the Atlantic albacore (T. alalunga) fishery. CTDDM obtained the 80% confidence interval of MSY (maximum sustainable yield) of (21 510 t, 23 118t). The catch in 2011 (24 100 t) is higher than the MSY values and the relative fishing mortality ratio (F2011/FMSY) is higher than 1.0. The results of CTDDM were analyzed to verify the proposed methodology and provide reference information for the sustainable management of the southern Atlantic albacore stock. The CTDDM treats the recruitment, the growth, and the mortality rates as all varying continuously over time and fills gaps between ASPM and SPM in this stock assessment.

Evaluation of the fishery status for King Soldier Bream Argyrops spinifer in Pakistan using the software CEDA and ASPIC

Catch and effort data were analyzed to estimate the maximum sustainable yield (MSY) of King Soldier Bream, Argyrops spinifer (Forsskal, 1775, Family: Sparidae), and to evaluate the present status of the fish stocks exploited in Pakistani waters. The catch and effort data for the 25-years period 1985–2009 were analyzed using two computer software packages, CEDA (catch and effort data analysis) and ASPIC (a surplus production model incorporating covariates). The maximum catch of 3 458 t was observed in 1988 and the minimum catch of 1 324 t in 2005, while the average annual catch of A. spinifer over the 25 years was 2 500 t. The surplus production models of Fox, Schaefer, and Pella Tomlinson under three error assumptions of normal, log-normal and gamma are in the CEDA package and the two surplus models of Fox and logistic are in the ASPIC package. In CEDA, the MSY was estimated by applying the initial proportion (IP) of 0.8, because the starting catch was approximately 80% of the maximum catch. Except for gamma, because gamma showed maximization failures, the estimated results of MSY using CEDA with the Fox surplus production model and two error assumptions, were 1 692.08 t (R2=0.572) and 1 694.09 t (R2=0.606), respectively, and from the Schaefer and the Pella Tomlinson models with two error assumptions were 2 390.95 t (R2=0.563), and 2 380.06 t (R2=0.605), respectively. The MSY estimated by the Fox model was conservatively compared to the Schaefer and Pella Tomlinson models. The MSY values from Schaefer and Pella Tomlinson models were the same. The computed values of MSY using the ASPIC computer software program with the two surplus production models of Fox and logistic were 1 498 t (R2=0.917), and 2 488 t (R2=0.897) respectively. The estimated values of MSY using CEDA were about 1 700–2 400 t and the values from ASPIC were 1 500–2 500 t. The estimates output by the CEDA and the ASPIC packages indicate that the stock is overfished, and needs some effective management to reduce the fishing effort of the species in Pakistani waters.

Maximum sustainable yield of Greater lizardfish Saurida tumbil fishery in Pakistan using the CEDA and ASPIC packages

The catch and effort data analysis (CEDA) and ASPIC (a stock assessment production model incorporating covariates) computer software packages were used to estimate the maximum sustainable yield (MSY) from the catch and effort data of Greater lizardfish Saurida tumbil fishery of Pakistan from 1986 to 2009. In CEDA three surplus production models of Fox, Schaefer and Pella-Tomlinson were used. Here initial proportion (IP) of 0.5 was used because the starting catch was roughly 50% of the maximum catch. With IP = 0.5, the estimated MSY from Fox model were 20.59 mt and 38.16 mt for normal and log-normal error assumptions, while the MSY from Schaefer and Pella-Tomlinson were 60.40, 60.40 and 60.40 mt, for normal, log-normal and gamma error assumptions respectively. The MSY values from Schaefer and Pella-Tomlinson models of three error assumptions were the same. The R2 values from those three models were above 0.6. When IP = 0.5, the MSY values estimated from ASPIC from Fox were 132 mt, and from logistic model were 69.4 mt, with R2 value above 0.8. Therefore we suggest the MSY of S. tumbil fishery from Pakistan to be 60–70 mt, which is higher than the latest catch, thus we would recommend that the fishing efforts for this fishery may be kept at the current level.

Cultivating the marine microalga Nannochloropsis salina under various nitrogen sources: Effect on biovolume yields, lipid content and composition, and invasive organisms

Algae can be a viable source for biofuel production, but the source of nitrogen used to cultivate could affect algae yields. Here, we observe how various nitrogen treatments can impact the growth and biovolume of microalga Nannochloropsis salina as well as invasion of undesired organisms. Invading organisms increase the likelihood of crashes of the desired microalgae culture. Experiments were conducted over 28 days in open aquaria in a greenhouse. We used five different nitrogen treatments; ammonium chloride (NH4Cl), ammonium hydroxide (NH4OH), sodium nitrate (NaNO3), urea (CH4N2O), and a mixture of all these sources. Highest values for Maximum Sustainable Yield (MSY), a measure of potential harvest rate based on population productivity, were observed in the urea treatment, but cell size was smaller compared to other treatments. Sodium nitrate and the mixture of nitrogen sources also had high MSY values but larger cell sizes, making them the treatments with highest total biovolume. The highest percentages of lipid by weight, but also highest densities of invading organisms were observed in the mixed treatment. Our results suggest that tradeoffs between biovolume and lipid yields as well as culture success can ultimately decide what nitrogen sources to use.

Worrisome trends in global stock status continue unabated: a response to a comment by R.M. Cook on “What catch data can tell us about the status of global fisheries”

In a previous contribution to this journal (Froese et al. 2012), we refuted criticism of a simple method (Froese and Kesner-Reyes 2002) that derives information about the status of global stocks from global catch data. This method assumes that, for a given stock, the ratio of current catches to previous maximum catches (Cmax) is indicative of the likely current exploitation status of the stock. For example, the method considers a stock as ‘‘collapsed’’ if current catch is \10 % of the previous maximum catch. The method also assumes that current catches in the range of 0.5–1.0 Cmax are indicative of fully exploited stocks, implying that the maximum sustainable yield (MSY) would also fall into that range. This assumption was supported by the observation (Froese et al. 2012) that the median MSY/Cmax ratio in 50 fully assessed stocks of the Northeast Atlantic was 0.62 (95 % confidence limits 0.56–0.70). Also, a plot of log(Cmax) over log(MSY) for these stocks showed a high correlation with little variance around the regression line. Such correlation has also been found by other studies for other stocks (Srinivasan et al. 2010; Halpern et al. 2012). Thus, in our previous paper, we concluded that ‘‘it seems justified to assume that in a majority of fisheries, catch levels of 0.5–1.0 Cmax are indicative of fully exploited stocks’’ (Froese et al. 2012). A comment by Cook (2013) challenges this assumption, asserting that ‘‘Unfortunately, these analyses do not support their contention that MSY for a particular stock is related to maximum catch in a predictable way ’’ In support of this statement, Cook (2013) points out that the 95 % range of MSY/Cmax ratios for the 50 analyzed stocks spans from 0.34 to 1.19, thus exceeding the assumed range of 0.5–1.0. However, given that we expected our method to make correct classifications not for 95 % but only for a majority of stocks, the fact that our range is located at the very center of the wider 95 % range does not contradict, but rather supports our assumption. Also, Figure 1d in Cook (2013), which presents the frequency distribution of MSY/Cmax ratios, shows sharp drop-offs in frequency below 0.5 and above 1.0, further confirming that the range we selected is reasonable. Cook (2013) also criticizes our regression of log(Cmax) over log(MSY), pointing out that such a relationship was trivial, because ‘‘It is obvious that small stocks will have a low MSY and large stocks will have a high MSY.’’ Because of this scale effect, ‘‘[...] any random catch [...] is highly correlated with MSY when examined across stocks of widely differing magnitude.’’ We agree with this point, because it leads to the logical conclusion that the maximum catch that can be taken from a stock is related to its size. However, if we assume that the maximum catches that fisheries can take in the real world are approximated by the reported maximum catches of stocks that are exploited sufficiently to be included in global statistics, then it also follows that these observed maximum catches (Cmax) are related to their respective stock sizes and their corresponding MSY values, a point that was disputed by our critics (e.g., Daan et al. 2011). This inference is confirmed by Figure 1a in Cook (2013), which shows regressions of maximum and random catch over MSY, on log-scales. Consistent with the above reasoning, the regression line representing Cmax lies above the regression line with Communicated by U. Sommer.

Evaluation of logistic surplus production model through simulations

A simulation study was conducted to evaluate the reliability of estimates of maximum sustainable yield (MSY), the biomass at which the MSY is obtained (Bmsy), the exploitation rate required to achieve the MSY (Emsy), and the intrinsic population growth rate (r), from a logistic production model fitted to catch and catch-rate data generated from an age-structured model. Both process (recruitment) and observation errors were considered. Natural mortality rate (M) and stock–recruitment steepness (h) values were used to construct productivity scenarios. Virtually all MSY estimates were between 50% and 150% of the “true”MSY values, although the Bmsy and Emsy were largely over- and under-estimated, respectively, in the absence of process and observation error. The MSY estimates were still reasonably accurate, but less reliable when h was low (<0.45) in the presence of process and observation error. About 87% of the MSY estimates were between 50% and 150% of the “true”MSY values when the coefficient of variation for the process and observation errors were both 30% (30–30% case), while 60% of the MSY estimates were between 50% and 150% of the “true”MSY values for the 80–30% case. Overestimation of MSY increased with increasing process error. The probability of overestimation of MSY increased from 0.59 (30–30% case) to 0.85 (80–30% case), suggesting that caution is needed when using an estimate of MSY from the logistic production model to design a management plan, especially for populations with low productivity. Bmsy was more likely overestimated and Emsy was, in general, conservatively estimated. The estimates of Bmsy and Emsy seemed to be useful for a benchmark for evaluation of the stock status and for selecting harvesting intensities, respectively.

A new approach of fitting biomass dynamics models to data

A non-traditional approach of fitting dynamic resource biomass models to data is developed in this paper. A variational adjoint technique is used for dynamic parameter estimation. In the variational formulation, a cost function measuring the distance between the model solution and the observations is minimized. The data assimilation method provides a novel and computationally efficient procedure for combining all available information, i.e., the data and the model in the analysis of a resource system. This technique will be used to analyze data for the North-east Arctic cod stock. Two alternative population growth models: the logistic and the Gompertz model are used for estimating parameters of simple bioeconomic models by the method of constrained least squares. Estimates of the parameters of the models dynamics are reasonable and can be accepted. The main inference from the work is that the average fishing mortality is found to be significantly above the maximum sustainable yield value.