scholarly journals Food for thought: pretty good multispecies yield

2016 ◽  
Vol 74 (2) ◽  
pp. 475-486 ◽  
Author(s):  
Anna Rindorf ◽  
Catherine Mary Dichmont ◽  
Phillip S. Levin ◽  
Pamela Mace ◽  
Sean Pascoe ◽  
...  
Keyword(s):  
Fisheries Management ◽  
Single Species ◽  
Maximum Sustainable Yield ◽  
Social Benefits ◽  
Sustainable Yield ◽  
Average Yield ◽  
Operational Management ◽  
Operating Space ◽  
Management Advice ◽  
Safe Operating

Abstract MSY principles for marine fisheries management reflect a focus on obtaining continued high catches to provide food and livelihoods for humanity, while not compromising ecosystems. However, maintaining healthy stocks to provide the maximum sustainable yield on a single-species basis does not ensure that broader ecosystem, economic, and social objectives are addressed. We investigate how the principles of a “pretty good yield” range of fishing mortalities assumed to provide >95% of the average yield for a single stock can be expanded to a pretty good multispecies yield (PGMY) space and further to pretty good multidimensional yield to accommodate situations where the yield from a stock affects the ecosystem, economic and social benefits, or sustainability. We demonstrate in a European example that PGMY is a practical concept. As PGMY provides a safe operating space for management that adheres to the principles of MSY, it allows the consideration of other aspects to be included in operational management advice in both data-rich and data-limited situations. PGMY furthermore provides a way to integrate advice across stocks, avoiding clearly infeasible management combinations, and thereby hopefully increasing confidence in scientific advice.

OPTIMAL IMPULSIVE HARVESTING OF A SINGLE-SPECIES WITH GOMPERTZ LAW OF GROWTH

2006 ◽  
Vol 14 (02) ◽  
pp. 303-314 ◽  
Author(s):  
YUJUAN ZHANG ◽  
ZHILONG XIU ◽  
LANSUN CHEN
Keyword(s):  
Global Attractivity ◽  
Population Level ◽  
Single Species ◽  
Maximum Sustainable Yield ◽  
Discrete Dynamical Systems ◽  
Optimal Harvesting ◽  
Sustainable Yield ◽  
Gompertz Law ◽  
Optimal Population ◽  
Impulsive Harvesting

In this paper we investigate the optimal harvesting problems of a single species with Gompertz law of growth. Based on continuous harvesting models, we propose impulsive harvesting models with constant harvest or proportional harvest. By using the discrete dynamical systems determined by the stroboscopic map, we discuss existence, stability and global attractivity of positive periodic solutions, and obtain the maximum sustainable yield and the corresponding optimal population level. At last, we compare the maximum sustainable yield of impulsive harvest with that of continuous harvest, and point out that proportional harvest is superior to constant harvest.

scholarly journals The good, the bad and the ugly of marine reserves for fishery yields

2015 ◽  
Vol 370 (1681) ◽  
pp. 20140276 ◽  
Author(s):  
Giulio A. De Leo ◽  
Fiorenza Micheli
Keyword(s):  
Stochastic Model ◽  
Larval Dispersal ◽  
Environmental Variability ◽  
Marine Reserves ◽  
Maximum Sustainable Yield ◽  
Social Benefits ◽  
Spatially Explicit ◽  
Sustainable Yield ◽  
Population Abundance ◽  
Quota Management

Marine reserves (MRs) are used worldwide as a means of conserving biodiversity and protecting depleted populations. Despite major investments in MRs, their environmental and social benefits have proven difficult to demonstrate and are still debated. Clear expectations of the possible outcomes of MR establishment are needed to guide and strengthen empirical assessments. Previous models show that reserve establishment in overcapitalized, quota-based fisheries can reduce both catch and population abundance, thereby negating fisheries and even conservation benefits. By using a stage-structured, spatially explicit stochastic model, we show that catches under quota-based fisheries that include a network of MRs can exceed maximum sustainable yield (MSY) under conventional quota management if reserves provide protection to old, large spawners that disproportionally contribute to recruitment outside the reserves. Modelling results predict that the net fishery benefit of MRs is lost when gains in fecundity of old, large individuals are small, is highest in the case of sedentary adults with high larval dispersal, and decreases with adult mobility. We also show that environmental variability may mask fishery benefits of reserve implementation and that MRs may buffer against collapse when sustainable catch quotas are exceeded owing to stock overestimation or systematic overfishing.

scholarly journals PENGELOLAAN BERKELANJUTAN PERIKANAN TANGKAP WADUK CIRATA : MODEL BIO-EKONOMI

2016 ◽  
Vol 11 (2) ◽  
pp. 161
Author(s):  
Zuzy Anna
Keyword(s):  
Parameter Estimation ◽  
Open Access ◽  
Fisheries Management ◽  
Economic Model ◽  
Gompertz Model ◽  
Maximum Sustainable Yield ◽  
Policy Implications ◽  
Fishing Gear ◽  
Sustainable Yield ◽  
Maximum Economic Yield

Perikanan tangkap di waduk, merupakan potensi yang dapat diandalkan bagi pemenuhan kebutuhan hidup masyarakat sekitarnya, sayangnya kegiatan ini belum banyak mendapat perhatian pengelolaan. Terbukti dari masih sangat rendahnya kontribusi sektor perikanan tangkap waduk ini pada perekonomian daerah. Untuk digunakan sebagai basis pengelolaan, penelitian ini dilakukan untuk menganalisis  pengaruh aktivitas produksi (penangkapan) terhadap kondisi sumber daya ikan seperti parameter biologi dan rente sumberdaya perikanan pada kondisi aktual, lestari, dan juga optimal, dengan menggunakan model bio-ekonomi standard logistik dan Gompertz. Skenario model yang digunakan adalah analisis bio-ekonomi model logistik Gordon Schaefer (GS) dengan estimasi parameter algoritma Fox, dan model Fox/Gompertz dengan estimasi  parameter biologi seluruhnya algoritma CYP. Analisis perikanan tangkap dilakukan dengan menggunakan skenario rezim pengelolaan open access, Maximum Sustainable Yield (MSY) dan Maximum Economic Yield (MEY). Hasil penelitian menunjukan adanya overfishing dan overcapacity pada beberapa tahun pengamatan yang ditandai dengan adanya kelebihan effort baik pada Model GS maupun Gompertz. Pengelolaan dengan menggunakan rezim MEY memberikan nilai rente yang paling maksimum, dengan biomass yang lebih konservatif, dan  effort yang lebih efisien, baik pada model GS maupun model Gompertz. Implikasi kebijakan pengelolaan waduk melalui rasionalisasi jumlah alat tangkap. Model MSY mengisyaratkan rasionalisasi alat tangkap lebih sedikit dibandingkan model MEY, sementara Model Gompertz mengisyaratkan penurunan alat tangkap lebih tinggi dibandingkan model GS. Alternatif pembatasan output atau kuota output juga dapat dilakukan dengan menggunakan nilai JTB. Title: Sustainable Fisheries Management in Cirata Dam: Bio-Economic ModellingCapture fisheries in the dam is a potential that can be relied for the surrounding community subsistence. Unfortunately this activity has not received much attention management. This was evident from the very low dam fisheries contribution, to the regional economy. For the purpose of fisheries management in the dam, this study was conducted to analyze the effect of production activities, on the condition of fish resources such as biological parameters and fishery resource rents on actual conditions, sustainable, and optimally, using bio-economic model of standard logistic and Gompertz. The scenario model used is the analysis of bio-economic model of logistics Gordon Schaefer (GS) with the parameter estimation of Fox algorithm, and  Gompertz model  with algorithm CYP  for biological parameter estimation. Analysis of fisheries carried out by using a scenario of open access management regime, Maximum Sustainable Yield (MSY) and the Maximum Economic Yield (MEY). The results showed overfishing and overcapacity in several years of observation which is characterized by an excess of effort both on the GS model and Gompertz. Management using MEY regime provides the maximum possible value of rents, with biomass more conservative and more efficient effort, both on the GS model and the model of Gompertz. Policy implications reveal from the study is dam management through the rationalization of the number of fishing gear or boats. MSY model suggests rationalization of fishing gear less than the model MEY, while the Gompertz model implies a decrease in fishing gear higher than the GS model. Alternative output restrictions or quotas outputs can also be implemented by using the value of total allowable catch.

Impacts of historical warming on marine fisheries production

Science ◽  
2019 ◽  
Vol 363 (6430) ◽  
pp. 979-983 ◽  
Author(s):  
Christopher M. Free ◽  
James T. Thorson ◽  
Malin L. Pinsky ◽  
Kiva L. Oken ◽  
John Wiedenmann ◽  
...  
Keyword(s):  
Climate Change ◽  
Fisheries Management ◽  
Food Production ◽  
Maximum Sustainable Yield ◽  
Marine Fishes ◽  
Sustainable Yield ◽  
Food Provisioning ◽  
Temperature Dependent ◽  
Potential Food

Climate change is altering habitats for marine fishes and invertebrates, but the net effect of these changes on potential food production is unknown. We used temperature-dependent population models to measure the influence of warming on the productivity of 235 populations of 124 species in 38 ecoregions. Some populations responded significantly positively (n = 9 populations) and others responded significantly negatively (n = 19 populations) to warming, with the direction and magnitude of the response explained by ecoregion, taxonomy, life history, and exploitation history. Hindcasts indicate that the maximum sustainable yield of the evaluated populations decreased by 4.1% from 1930 to 2010, with five ecoregions experiencing losses of 15 to 35%. Outcomes of fisheries management—including long-term food provisioning—will be improved by accounting for changing productivity in a warmer ocean.

scholarly journals An investigation into fisheries interaction effects using Atlantis

2014 ◽  
Vol 72 (1) ◽  
pp. 275-283 ◽  
Author(s):  
Michael D. Smith ◽  
Elizabeth A. Fulton ◽  
Robert W. Day
Keyword(s):  
Fisheries Management ◽  
Carrying Capacity ◽  
Stock Assessment ◽  
Single Species ◽  
Interaction Effects ◽  
Fishing Effort ◽  
Maximum Sustainable Yield ◽  
Simultaneous Increase ◽  
Total Catch ◽  
The Impact

Abstract Fisheries management is commonly based on the outputs of single-species stock assessment models. While such models are appropriate for tactical issues such as quota setting, they typically omit explicit trophic interactions between different parts of the ecosystem. To successfully manage multiple fisheries in the same ecosystem, we need to understand how fishing one species may indirectly affect other species. In this paper, we used a simulation model of the southern Benguela ecosystem, built in the Atlantis framework, to explore fisheries interaction effects. We first measured the impact of fishing different stocks individually at FMSY, the hypothetical level of fishing effort which produces maximum sustainable yield (MSY) in a single-species modelling context. We then applied FMSY to all stocks simultaneously and compared the simultaneous yield with the sum of yields from the individual applications of FMSY. Contrary to expectations, the total catch was higher under the simultaneous scenario. We explored our results by studying the influences of trophic interaction between species at different levels of the foodweb, and found that our overall result was driven by two key factors: volumetric dominance of small pelagic fish in the total catch, and asymmetric influences of competition and predation between piscivorous and planktivorous species. The simultaneous increase in fishing pressure across multiple species in the model led to increased effective carrying capacity for small pelagic species (due to reduced competition), but reduced carrying capacity for piscivorous species (due to reduced small pelagic prey). This work has important implications for the design of tactical multispecies models for use in ecosystem-based fisheries management.

Effectiveness of lobster fisheries management in New Zealand and Nova Scotia from multi-species and ecosystem perspectives

2016 ◽  
Vol 74 (1) ◽  
pp. 146-157 ◽  
Author(s):  
Tyler D. Eddy ◽  
Julio N. Araújo ◽  
Alida Bundy ◽  
Elizabeth A. Fulton ◽  
Heike K. Lotze
Keyword(s):  
New Zealand ◽  
Nova Scotia ◽  
Fisheries Management ◽  
Single Species ◽  
Homarus Americanus ◽  
Maximum Sustainable Yield ◽  
Ecosystem Impacts ◽  
Ecosystem Effects ◽  
Trade Offs ◽  
Large Predators

In New Zealand and Nova Scotia, lobster (Jasus edwardsii and Homarus americanus, respectively) is the most valuable export fishery. Although stock assessments and indicators assist in evaluating lobster fisheries, ecosystem effects are largely unknown, hindering ecosystem-based fisheries management (EBFM). We employed ecosystem models for the Cook Strait, New Zealand and western Scotian Shelf, Nova Scotia, Canada, to evaluate trade-offs between catches and ecosystem impacts in lobster fisheries from single- and multi-species perspectives. We ran simulations to independently determine exploitation rates that produced maximum sustainable yield (MSY) for lobster, and for all fished groups. We then ran simulations using these MSY exploitation rates simultaneously, and simulations to maximize multi-species MSY (MMSY). Our results indicate that current lobster exploitation rates in both regions are greater than those producing MSY, and have significant ecosystem impacts. Simulating multi-species fisheries, in both systems the sum of single-species MSY for all fished groups was less than the sum of catches where exploitation rates were run simultaneously. Runs maximizing MMSY across the entire ecosystem increased exploitation rates on many fished groups, and produced even greater total catch—yet with much greater ecological costs—and in Nova Scotia, collapses of sharks, large predators, and lobster themselves. As fisheries management moves towards multi-species and ecosystem-based approaches, we suggest that MMSY targets should be treated similarly to MSY—not as a target, but a limit. Even then, careful evaluation is required before implementation to ensure that there are no undesirable economic or ecological consequences.

Sign in / Sign up

Export Citation Format

Share Document