Effects of predator–prey interactions and adaptive change on sustainable yield

2004 ◽  
Vol 61 (2) ◽  
pp. 175-184 ◽  
Author(s):  
Hiroyuki Matsuda ◽  
Peter A Abrams

We explore the effects on population size and yield of different levels of harvesting of a predator in a predator–prey system. We consider the consequences of adaptive change in the predator's foraging time (or effort) and feedback control of fishing effort. The predator may increase in population size with increasing fishing effort, either when the prey is characterized by a positive effect of its own population size on its own growth rate or when the prey is overexploited by the predator. The predator abundance at which the sustainable yield is maximized can be larger than the abundance without fishing. The effort that achieves maximum sustainable yield and the effort that maximizes predator abundance can both be close to the effort at which the stock collapses. Feedback control in the response to predator abundance may fail to achieve the desired abundance of the target stock or its prey even if the fishing effort is well controlled. These results suggest that developing policies for exploiting adaptive predator species in potentially cycling systems cannot be based on the stable single-species models often used in fisheries management.

2019 ◽  
Vol 24 (5) ◽  
Author(s):  
Debabrata Das ◽  
Tapan Kumar Kar

This article examines the effectiveness of feedback control as a management policy on a generalist predator–prey system with prey harvesting. We discuss the result of implementing feedback control with respect to prey and predator separately. This paper also depicts the effect of exploitations up to maximum sustainable yield (MSY). We observe that with a constant fishing effort MSY policy is a sustainable management policy to protect both the species. However, further increase of fishing effort may cause the extinction of prey species. But considering feedback control of fishing effort may restrict the extinction of prey species. When fishing effort is controlled in terms of prey density, the extinction of prey population can be avoided. In this case, there may be coexistences of prey, predator and fishery or extinction of fishery. But when fishing effort is controlled by predator density, it is difficult to manage the coexistences of prey, predator and fishery.  


2012 ◽  
Vol 3 ◽  
pp. 105
Author(s):  
Mario A. Gómez-Ponce ◽  
María Isabel Gallardo-Berumen ◽  
Fabián Cervantes-Hernández

Oreochromis spp. fishing in the Fernando Hiriart Balderrama Reservior began in 1997 and its effects had never been studied before. Schaefer and Fox’s biomass dynamic model were used in order to obtain the first evaluation of this resource and to analyze the presence of record errors (or observation errors) in the annual total catch data set. The number of fishermen was used as the fishing effort unit. Schaefer´s model proved to be statically reliable: Oreochromis spp. was estimated at the maximum population size value of k = 9 000 tons and reproduction rate value at annual r = 0.730. Considering those ecological and biological strategies, Schaefer´s model showed that great biomass levels (predicted biomass) have been produced in the Zimapán reservior; however, only a small part of this biomass was exploited during the analyzed period. The results indicate that tilapia fishery in the Zimapán Reservoir was at equilibrium or was not over-fished between 1997 and 2006 because historical tilapia records observed in Schaefer´s model were far from the k parameter and below the MSY value. With this exploitation type, the fishing effort can increase to up to 7 203 fishermen (level of fishing effort at which the maximum sustainable yield is achieved (fMSY)). However, in order to avoid an increase of the non-controlled fishing effort a similar analysis is recommended with recent data. La pesca de la tilapia Oreochromis spp. en la presa hidroeléctrica Fernando Hiriart Balderrama comenzó en 1997, esta pesquería nunca ha sido evaluada. Fueron utilizados los modelos dinámicos de biomasa de Schaefer y Fox para obtener la primera evaluación de este recurso y para analizar la presencia de errores de registro (errores de observación) en la captura anual total. El número de pescadores fue usado como la unidad de esfuerzo de pesca. El modelo de Schaefer resultó estadísticamente confiable y para Oreochromis spp. fueron estimados el tamaño máximo de población en k = 9 000 tons y la tasa de reproducción en r = 0.730 anual. Considerando estas estrategias ecológicas y biológicas, el modelo de Schaefer sugirió que grandes niveles de biomasa (biomasa predicha) fueron producidas en la presa Zimapán, pero solo una pequeña parte de esta biomasa fue explotada durante el periodo analizado. Los resultados indicaron que la pesquería de la tilapia en la presa Zimapán estuvo en equilibrio o no fue sobreexplotada entre 1997 y el 2006, porque los registros históricos en el modelo de Schaefer fueron observados muy lejos del parámetro k y por debajo del valor MSY. Con este tipo de explotación, el esfuerzo de pesca podría incrementarse hasta alcanzar 7 203 número de pescadores (nivel de esfuerzo de pesca en el cual se activa el rendimiento máximo sostenible (fMSY)), pero para evitar un incremento no controlado del esfuerzo de pesca, se recomienda hacer un análisis similar integrando datos recientes.


2020 ◽  
Vol 25 (3) ◽  
Author(s):  
Kanisha Pujaru ◽  
Tapan Kumar Kar

This paper gives a broad outline of some comparative analysis of two ecological services, namely, yield and resilience of a generalist predator–prey system. Although either prey or predator species can be harvested at maximum sustainable yield (MSY) level, yet there is a trade-off between yield and resilience. When both the species are harvested simultaneously, MSY increase by changing catchabilities always increases the system resilience both in prey- and predator-oriented fishery. In particular, a prey-oriented fishery with low prey catchability gives more yield and resilience but in case of predator-oriented fishery with high predator catchability, gives more of these ecological services. Thus to get both the optimum yield and resilience, a balanced harvesting approach is needed between the prey and predator trophic levels. Throughout the analysis, we use both the analytical as well as numerical techniques.  


1978 ◽  
Vol 35 (9) ◽  
pp. 1249-1261 ◽  
Author(s):  
G. H. Winters

From recent and historical data the natural mortality rate of adult harp seals (Pagophilus groenlandicus) is estimated to be 0.10 which is within the range of previous estimates (0.08–0.11). New estimates of bedlamer and 0-group natural mortality rates were not significantly different from those of adult seals. Pup production estimates from survival indices agreed well with those from sequential population analyses and indicated a decline from about 350 000 animals in the early 1950s to about 310 000 animals in the early 1970s. Over the same period the 1+ population size declined from 2.5 to 1.1 million animals but has been increasing at the rate of 3%/yr since the introduction of quotas in 1972. The relative contribution of the "Front" production to total ("Front" plus Gulf) production during the past decade has fluctuated from 49 to 87%, the average of 64% being very similar to the 61% obtained previously. These fluctuations suggest some interchange between "Front" and Gulf adults and it is concluded that homing in the breeding areas is a facultative rather than obligatory aspect of seal behavior. Thus the heavier exploitation of the "Front" production is probably sufficiently diffused into the total population to avoid serious effects on "Front" production. The maximum sustainable yield of Northwest Atlantic seals harvested according to recent patterns is estimated to be 290 000 animals (80% pups) from a 1+ population size of 1.8 million animals producing 460 000 pups annually. The sustainable yield at present levels of pup production (335 000 animals) is calculated to be 220 000 animals which is substantially above the present TAC of 180 000 animals and coincides with present harvesting strategies designed to enable the seal hunt to increase slowly towards the MSY level. Key words: mortality, production, sustainable yield, population dynamics, marine mammal


2009 ◽  
Vol 6 (1) ◽  
pp. 124-127 ◽  
Author(s):  
Henrik Sparholt ◽  
Robin M. Cook

The theory of maximum sustainable yield (MSY) underpins many fishery management regimes and is applied principally as a single species concept. Using a simple dynamic biomass production model we show that MSY can be identified from a long time series of multi-stock data at a regional scale in the presence of species interactions and environmental change. It suggests that MSY is robust and calculable in a multispecies environment, offering a realistic reference point for fishery management. Furthermore, the demonstration of the existence of MSY shows that it is more than a purely theoretical concept. There has been an improvement in the status of stocks in the Northeast Atlantic, but our analysis suggests further reductions in fishing effort would improve long-term yields.


2019 ◽  
Vol 10 (1) ◽  
pp. 18
Author(s):  
Donald H. Simanjuntak ◽  
Lawrence J. L. Lumingas ◽  
Joudy R. R. Sangari

This research was conducted in the city of Bitung, North Sulawesi Province with activities centered on the Bitung Ocean Fisheries Port (PPS), which began from mid March to April 2019. The fishing activities studied are using the fishing areas around the waters of  North Sulawesi Province namely the Sulawesi Sea and The Maluku Sea which are included in WPP 715 and 716 based on tuna catch landed data on PPS Bitung. The purpose of this study was to analyze the value of sustainable potential by looking at the level of utilization and Maximum Sustainable Yield (MSY) of tuna in the waters around North Sulawesi Province based on a surplus production model approach (Schaefer Model). This research is expected to be used as a consideration in the management of tuna stocks around the waters of North Sulawesi Province, and can be used as a basis for further research. This study uses a secondary data collection method in the form of fishery statistics documents. The data used are data from tuna fishing and fishing (effort), from 2014 to 2018 (5 years). The results showed that the sustainable potential of tuna fisheries around the waters of North Sulawesi Province based on North Sulawesi PPS data indicated that, the sustainable potential value of tuna that could be caught was 14,173.51 tons / year which is counted as 80% of the value of tuna resources around the waters of North Sulawesi Province. PPS Bitung data which amounted to 17,716.15 tons / year for Hmsy, 1,200.15 trips / year for Emsy, with an average CPUE value of 2014-2018 of 19 tons / trip. The level of tuna utilization around the waters of North Sulawesi Province is based on data from PPS Bitung in 2014, 2017 and 2018 which indicate that there were indications of overfishing with the largest utilization rate in 2014 which reached a value of 155.09%.Keywords: tuna, Bitung, Bitung PPS, sustainable potential, MSY. ABSTRAKKegiatan penelitian ini berlangsung di Kota Bitung, Provinsi Sulawesi Utara dengan kegiatan berpusat di Pelabuhan Perikanan Samudera (PPS) Bitung, yang dimulai  dari pertengahan bulan Maret hingga bulan April 2019. Aktivitas perikanan tangkap yang ditelaah berlangsung di sekitar perairan Provinsi Sulawesi Utara yaitu Laut Sulawesi dan Laut Maluku yang masuk ke dalam WPP 715 dan 716 berdasarkan data tangkapan tuna yang didaratkan di PPS Bitung. Tujuan dari penelitian ini adalah untuk menganalisis nilai potensi lestari dengan melihat tingkat pemanfaatan dan maximum sustainable yield (MSY) ikan tuna di sekitar perairan Provinsi Sulawesi Utara berdasarkan pendekatan model produksi surplus (Model Schaefer). Penelitan ini diharapkan dapat digunakan sebagai bahan pertimbangan dalam pengelolaan stok ikan tuna di sekitar perairan Provinsi Sulawesi Utara, serta dapat digunakan sebagai dasar untuk penelitian selanjutnya.  Penelitian ini menggunakan metode pengumpulan data sekunder berbentuk dokumen. Data yang diambil adalah data tangkapan ikan tuna dan upaya penangkapan ikan atau effort (trip), dari tahun 2014 sampai dengan 2018 (5 Tahun). Hasil penelitian menunjukkan potensi lestari perikanan tuna di sekitar perairan Provinsi Sulawesi Utara berdasarkan data PPS Bitung Sulawesi Utara nilai potensi lestari tuna yang bisa ditangkap adalah 14.173,51 ton/tahun 80% dari nilai pemanfaatan sumber daya perikanan tangkap tuna di sekitar perairan Provinsi Sulawesi Utara berdasarkan data PPS Bitung yang sebesar 17.716,15 ton/tahun untuk Hmsy, 1.200,15 trip/tahun untuk Emsy, dengan nilai CPUE rata-rata tahun 2014-2018 sebesar 19 ton/trip. Tingkat pemanfaatan tuna di sekitar perairan Provinsi Sulawesi Utara berdasarkan data PPS Bitung Sulawesi Utara di tahun 2014,2017 dan 2018 sudah yang menandakan adanya indikasi overfishing dengan tingkat pemanfaatan terbesar di tahun 2014 yang mencapai nilai 155,09%.Kata Kunci: ikan tuna, Bitung, PPS Bitung, potensi lestari, MSY.


Author(s):  
Ken H. Andersen

This chapter uses the community model to repeat many of the classic impact calculations of a single stock on the entire community. Here, a focus is the appearance of trophic cascades initiated by the removal of large predators. When a component of an ecosystem is perturbed, the effects are not isolated to the component itself but cascade through the ecosystem. Perturbations are mainly propagated through the predator–prey interactions. The chapter also considers the trade-offs between a forage fishery and a consumer fishery, and the extension of the maximum sustainable yield (MSY) concept to the community, before finally returning to the single-stock aspects.


2006 ◽  
Vol 14 (02) ◽  
pp. 303-314 ◽  
Author(s):  
YUJUAN ZHANG ◽  
ZHILONG XIU ◽  
LANSUN CHEN

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.


Crustacea ◽  
2020 ◽  
Author(s):  
Jorge Homero Rodriguez Castro ◽  
Sandra Edith Olmeda de la Fuente ◽  
Wanda Ortiz Baez ◽  
Alfonso Correa Sandoval ◽  
Jose Alberto Ramirez de León

2016 ◽  
Vol 74 (2) ◽  
pp. 475-486 ◽  
Author(s):  
Anna Rindorf ◽  
Catherine Mary Dichmont ◽  
Phillip S. Levin ◽  
Pamela Mace ◽  
Sean Pascoe ◽  
...  

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.


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