scholarly journals KETIDAKSTABILAN BESARAN STOK IKAN DARI MODEL PRODUKSI SURPLUS

2017 ◽  
Vol 13 (1) ◽  
pp. 1
Author(s):  
Suherman Banon Atmaja

Selama ini, kerangka pengelolaan sumber daya ikan berdasarkan pada titik acuan nilai potensi dan kriteria maksimum (maximum sustainable yield), mengabaikan laju pertumbuhan stok ikan dan tanpa memperhatikan dinamika perikanan yang terjadi. Dari kombinasi data yang tersedia diperoleh hasil besaran nilai stok ikan yang bersifat dinamis, akibat perubahan yang terjadi pada parameter–parameter model produksi surplus. Tingkat maximum sustainable yield menunjukkan CMSY darimetode Gompertz lebih tinggi dibandingkan dengan metode logistik, sebaliknya tingkat EMSY lebih rendah dibandingkan dengan metode logistik. Konsekuensi perbedaan tersebut menghasilkan tingkat BMSY dan tercapai puncak titik jenuh dari perikanan pukat cincin berbeda, untuk metode Gompertz (37% dari biomassa awal) terjadi pada kurun waktu tahun 1978 sampai dengan 1981, sedangkan untuk metode logistik (50% dari biomassa awal) terjadi pada kurun waktu tahun 1990 sampai dengan 1992. Kondisi trend biomassa menunjukkan penurunan biomassa berkisar 92 sampai dengan 96,5% dari biomassa awal untuk metode Gompertz, sedangkan untuk metode logistik berkisar 70 sampai dengan 93%. Tampak perkembangan perikanan pukat cincin catch effort mengikuti fungsi pertumbuhan logistik daripada fungsi pertumbuhan Gompertz. Bagaimanapun, penyusutan stok ikan pelagis didukung oleh trend hasil tangkapan yang menurun, sedangkan hari operasi cenderung meningkat. During the time, framework of fisheries resources management was based on reference point of potency value and criteria (maximum sustainable yield), while net growth of fish stock and fisheries dynamics have been ignored. From data combination available obtaining result of size of fish stocks was dynamic due to change of parameters of surplus production. The Level maximum sustainable yield showes that CMSY method of Gompertz was higher than logistics method, on the contrary EMSY compared to lower than logistics method. Consequently, these results were obtained the level of BMSY (biomass at level maximum sustainable yield) and the peaks of exploitation from purse seine fishery were also diffrent, for Gompertz method revealed that the level of BMSY (37% from initially biomass) occurred in the period of 1978 to 1981, while logistics method (50% from initially biomass) occurred in the period of 1990 to 1992. Trend biomass in state of decline reached 92 to 96,5% from intially biomass for Gompertz method, while for the method of logistics reached 70 to 93% from intially biomass. Seems that the development of purse seine fisheries (catch effort) followed function growth logistics rather than the function growth Gompertz. However, the decrease of fish stock pelagic supported by the catch of pelagic fish showed a declining trend, while fishing days have tend to increase.

2017 ◽  
Vol 8 (2) ◽  
pp. 713-728
Author(s):  
Yulia Estmirar Tanjov ◽  
Roza Yusfiandayani ◽  
. Mustaruddin

Lempasing is a Coastal Fishing Port (CFP) which located in Bandar Lampung. It is one of the centers of fisheries activities in the city. One of the fishing gear which operated by most of fishermen in Lempasing is mini purse seine. Mini purse seine fishing activities in the Lampung Bay Area and Lempasing CFP is not in accordance with the conditions of the surrounding waters area. The research was conducted in the Lampung Bay Area and Lempasing CFP, Lampung. This study aims to: 1) determine the status of fisheries resources utilization, 2) to describe the dominant fish caught by mini purse seine.  Analysis methods were used in this study namely: 1) Fishing Power Index (FPI), Catch Per Unit Effort (CPUE), and Maximum Sustainable Yield (MSY) to determine the status of fisheries resource utilization. The dominant small pelagic fishes caught were scad fish Selaroides sp., mackerel fish Rastrelliger sp., longnose trevally fish Carangoides chrysophrys. The result showed that Fox model was the best fits models with estimated maximum sustainable yield of 15.5 ton and fishing effort of 992 trip/year for mini purse seine. The longnose trevally fish in lampung bay area in do not exceeded the optimal catch fish condition can be used to sustainably. In these condition is necessary to wisely manage and setting the catches to not exceed the allowable catch of the small pelagic fish, so the stock of small pelagic fish in the Lampung Bay Area can be used sustainably.


2017 ◽  
Vol 8 (2) ◽  
pp. 713
Author(s):  
Yulia Estmirar Tanjov ◽  
Roza Yusfiandayani ◽  
. Mustaruddin

<p><em>Lempasing is a Coastal Fishing Port (CFP) which located in Bandar Lampung. It is one of the centers of fisheries activities in the city. One of the fishing gear which operated by most of fishermen in Lempasing is mini purse seine. Mini purse seine fishing activities in the Lampung Bay Area and Lempasing CFP is not in accordance with the conditions of the surrounding waters area. The research was conducted in the Lampung Bay Area and Lempasing CFP, Lampung. This study aims to: 1) determine the status of fisheries resources utilization, 2)</em><em> to describe the dominant fish caught by mini purse seine. </em><em> Analysis methods were used in this study namely: 1) Fishing Power Index (FPI), Catch Per Unit Effort (CPUE), and Maximum Sustainable Yield (MSY) to determine the status of fisheries resource utilization. The dominant small pelagic fishes caught were scad fish <span style="text-decoration: underline;">Selaroides</span> </em>sp<em>., mackerel fish <span style="text-decoration: underline;">Rastrelliger</span> </em>sp<em>., longnose trevally fish <span style="text-decoration: underline;">Carangoides</span> <span style="text-decoration: underline;">chrysophrys</span>. The result showed that Fox model was the best fits models with estimated maximum sustainable yield of 15.5 ton and fishing effort of 992 trip/year for mini purse seine. The longnose trevally fish in lampung bay area in do not exceeded the optimal catch fish condition can be used to sustainably. In these condition is necessary to wisely manage and setting the catches to not exceed the allowable catch of the small pelagic fish, so the stock of small pelagic fish in the Lampung Bay Area can be used sustainably.</em></p>


2017 ◽  
Vol 6 (1) ◽  
pp. 21
Author(s):  
David Y Rumambi ◽  
Unstain N. W. J. Rembet ◽  
Joudy R. R. Sangari

This research activity took place in Manado City, North Sulawesi Province with activities centered on the Tumumpa Fishery Harbor (PPP). The data were recorded from capture fisheries activity conducted in the Sulawesi Sea and its surroundings landed in the Tumumpa Fishery Harbor. The purpose of this study was to analyze the stock value and Maximum Sustainable Yield (MSY) of pelagic fish in the Sulawesi Sea based on the approach of the surplus production model (Model Schaefer). This research is expected to be used as a consideration in the management of pelagic fish stocks in the Sulawesi Sea, and can be used as a basis for further research. This research uses secondary data collection method in the form of statistical document and record available. The data taken, including fish catch and fishing effort or effort (trip), from 2012 to 2016 (5 years). The results show that production value is inversely proportional to the value of effort, where the value of production from 2012 to 2016 has decreased every year, while the value of effort from 2012 to 2016 has increased. This condition indicates that the presence of pelagic fish stocks in the Sulawesi Sea and surrounding areas has been and is experiencing a decline that impacts on the decrease of production every year with a large percentage and this condition also indicates the occurrence of potentially overfishing. The value of MSY utilization of capture fishery resources in the Sulawesi Sea based on Tumumpa Fishery Harbor data were 16,305.45 tons / year for HMSY and 1,664,59 trips / year for EMSY, with TAC of 13,044.36 tons / year.Keywords :  Capture fishery, MSY, Pelagic, Surplus Production Model, Tumumpa ABSTRAK Kegiatan penelitian ini berlangsung di Kota Manado, Provinsi Sulawesi Utara dengan kegiatan berpusat di Pelabuhan Perikanan Pantai (PPP) Tumumpa Manado. Aktivitas perikanan tangkap yang ditelaah berlangsung di kawasan perairan Laut Sulawesi dan sekitarnya berdasarkan data PPP Tumumpa Manado. Tujuan dari penelitian ini adalah untuk menganalisis nilai stok dan Maximum Sustainable Yield (MSY) ikan pelagis di Laut Sulawesi berdasarkan pendekatan model produksi surplus (Model Schaefer). Penelitan ini diharapkan dapat digunakan sebagai bahan pertimbangan dalam pengelolaan stok ikan pelagis di Laut Sulawesi dan sekitarnya, serta dapat digunakan sebagai dasar untuk penelitian selanjutnya. Penelitian ini menggunakan metode pengumpulan data sekunder berbentuk dokumen. Data yang diambil adalah data tangkapan ikan dan upaya penangkapan ikan atau effort (trip), dari tahun 2012 sampai dengan 2016 (5 Tahun). Hasil penelitian menunjukkan nilai produksi berbanding terbalik dengan nilai effort, di mana nilai produksi dari tahun 2012 sampai 2016 mengalami penurunan setiap tahunnya, sedangkan nilai effort dari tahun 2012 sampai tahun 2016 mengalami peningkatan. Kondisi yang terjadi ini mengindikasikan bahwa keberadaan stok ikan pelagis di Laut Sulawesi dan sekitarnya telah dan sedang mengalami penurunan yang berdampak pada penurunan produksi setiap tahun dengan persentase yang cukup besar di mana kondisi ini mengindikasikan terjadinya overfishing. Nilai MSY pemanfaatan sumber daya perikanan tangkap di Laut Sulawesi berdasarkan data PPP Tumumpa Manado sebesar 16.305,45 ton/tahun untuk HMSY, dan 1.664,59 trip/tahun untuk EMSY, dengan TAC sebesar 13.044,36 ton/tahun.Kata Kunci: Perikanan Tangkap, MSY, Pelagis, Model Produksi Surplus, Tumumpa


1998 ◽  
Vol 55 (8) ◽  
pp. 1971-1982 ◽  
Author(s):  
Mikko Heino

Mortality caused by harvesting can select for life history changes in the harvested stock. Should this possibility be taken into account in the management of renewable resources? I compare the performance of different harvest strategies when evolutionary change is accounted for with the help of an age-structured population dynamics model. Assuming that age of first reproduction is the only evolving trait, harvesting of only mature individuals selects for delayed maturation and results in increased sustainable yields. Unselective harvesting of both mature and immature fish selects for earlier maturation which causes the sustainable yield to decrease. Constant stock size and constant harvest rate strategies perform equally well in terms of maximum sustainable yield, both before and after evolutionary change. The maximum sustainable yield for fixed-quota strategies is lower. All those strategies have similar evolutionary consequences given a similar average harvest rate. Coevolutionary dynamics between fish stock and the stock manager indicate that the evolutionary benefits of selective harvesting are attainable without incurring yield losses in the near future.


2016 ◽  
Vol 22 (1) ◽  
pp. 9
Author(s):  
Sri Turni Hartati ◽  
Setiya Triharyuni ◽  
Lilis Sadiyah

The coastal of Makassar Strait is one of main fishing grounds for purse seine vessels from northern part of Java which based at the following landing sites, i.e. Pekalongan, Tegal and Juwana. The purse seine fishery predominantly targets small pelagic fish. This paper attempts to present the current condition of small pelagic fishery in the Makassar Strait. Catch and effort (trip) data between 2004 and 2011 from the three landing sites were used to estimate Maximum Sustainable Yield (MSY) using Schaefer & Fox models. The results showed a decreasing trend in the catch rate, from 30.83 tons/trip in 2004 to 12.27 tons/trip in 2011. The estimated MSY is at the range of 34,705- 37,930 tons with optimum efforts for 2,234-2,500 purse seine trips. Thus the level of purse seine fishing effort in 2011, i.e. 3,078 trips, was exceeding the optimum effort. The decreasing trend in the catch rate may indicate overfishing is occurring between 2004 and 2011. For management of the small pelagic fisheries in the waters of Makassar Strait, important action recommended is fishing effort restrictions. The effort allowed would be only in the range of 2,234-2,500 purse seine trips, and the fishing capacity needs to be controled.


Ocean Science ◽  
2013 ◽  
Vol 9 (2) ◽  
pp. 261-279 ◽  
Author(s):  
A. Christensen ◽  
M. Butenschön ◽  
Z. Gürkan ◽  
I. J. Allen

Abstract. First results of a coupled modelling and forecasting system for fisheries on habitat-bound stocks are being presented. The system consists currently of three mathematically, fundamentally different model subsystems coupled offline: POLCOMS providing the physical environment implemented in the domain of the north-west European shelf, the SPAM model which describes sandeel stocks in the North Sea, and the third component, the SLAM model, which connects POLCOMS and SPAM by computing the physical–biological interaction. Our major experience by the coupling model subsystems is that well-defined and generic model interfaces are very important for a successful and extendable coupled model framework. The integrated approach, simulating ecosystem dynamics from physics to fish, allows for analysis of the pathways in the ecosystem to investigate the propagation of changes in the ocean climate and to quantify the impacts on the higher trophic level, in this case the sandeel population, demonstrated here on the basis of hindcast data. The coupled forecasting system is tested for some typical scientific questions appearing in spatial fish stock management and marine spatial planning, including determination of local and basin-scale maximum sustainable yield, stock connectivity and source/sink structure. Our presented simulations indicate that sandeel stocks are currently exploited close to the maximum sustainable yield, even though periodic overfishing seems to have occurred, but large uncertainty is associated with determining stock maximum sustainable yield due to stock inherent dynamics and climatic variability. Our statistical ensemble simulations indicates that the predictive horizon set by climate interannual variability is 2–6 yr, after which only an asymptotic probability distribution of stock properties, like biomass, are predictable.


Science ◽  
2019 ◽  
Vol 365 (6454) ◽  
pp. eaax5721 ◽  
Author(s):  
Cody Szuwalski

Free et al. (Reports, 1 March 2019, p. 979) linked sea surface temperature (SST) to surplus production and estimated a 4% decline in maximum sustainable yield (MSY) since 1930. Changes in MSY are expected when fitting production models to age-structured data, so attributing observed changes to SST is problematic. Analyses of recruitment (a metric of productivity in the same database) showed increases in global productivity.


2018 ◽  
Vol 59 (2) ◽  
pp. 185-190
Author(s):  
Barbara Zorica ◽  
Vanja Čikeš Keč ◽  
Kristijan Zanki ◽  
Leon Grubišić ◽  
Tanja Šegvić-Bubić

Due to very good collaboration with one commercial purse seiner, using “Srdelara” and operating in fishing zone G, preliminary data concerning the interaction between small pelagic purse seine fishery and its predators were obtained. According to the notes taken by experience observer on-board in period from year 2013 to 2016, seems that tunas, dolphins and swordfish were the faithful companions of purse seiner fisherman with abundance of 68.6%, 22.0% and 9.4%, respectively. Although they were present all year round, their monthly pattern of appearance indicated that less tunas were recorded in May-June, more dolphins were noted from July to October while swordfish were mostly abundant in winter (January-March). Within the investigated period, slightly increasing trend of tuna and dolphins’ appearance was recorded, although statistically not significant. Analysing possible correlation between purse seine catches and predator’s abundances, revealed that appearance of tuna had negative impact on the catches (dispersion of schools), while realised catches in presence of dolphins were quite good so it seems that they tend to round up small pelagic fish schools.


1987 ◽  
Vol 44 (S2) ◽  
pp. s339-s348 ◽  
Author(s):  
R. B. Deriso

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).


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