scholarly journals PRODUKSI DAN PRODUKTIVITAS TUNA OLEH KAPAL TUNA LONGLINE YANG BERBASIS DI PPN PALABUHANRATU

2020 ◽  
Vol 10 (2) ◽  
pp. 173-181
Author(s):  
Mohammad Imron ◽  
Roza Yusfiandayani ◽  
Mulyono S. Baskoro
Keyword(s):  
Stock Assessment ◽  
Unit Effort ◽  
Thunnus Obesus ◽  
Thunnus Alalunga ◽  
Tuna Longline

Produktivitas penangkapan tuna dapat dilihat dari produksi penangkapan yang didaratkan di pelabuhan (landing) per upaya penangkapan (effort). Pelabuhan Perikanan Nusantara (PPN) Palabuhanratu menjadi salah satu pelabuhan perikanan yang aktivitas perikanannya tergolong aktif di wilayah pesisir selatan Pulau Jawa dan menjadi salah satu pusat kegiatan perikanan tangkap di wilayah Propinsi Jawa Barat. Produksi ikan tuna di PPN Palabuhanratu mengalami peningkatan yang cukup signifikan dari tahun 2010 sampai tahun 2019. Pada tahun 2014-2018 produksi ikan tuna di PPN Palabuhanratu mengalami penurunan yang cukup drastis. Pada tahun 2019, produksi kembali meningkat menjadi 1,091,612 ton. Landing Per Unit Effort (LPUE) digunakan dalam penelitian perikanan untuk mengindikasikan kelimpahan sumberdaya yang digunakan untuk melakukan stock assessment ketika mengestimasi kelimpahan relatif dari suatu spesies yang dieksploitasi. Komposisi hasil tangkapan tuna oleh kapal tuna longline terdiri atas ikan tuna sirip kuning (Thunnus albacores), tuna mata besar (Thunnus obesus), ikan tuna albakor (Thunnus alalunga). Produksi tuna yang didaratkan di PPN Palabuhanratu dari tahun 2010-2019 mengalami fluktuasi. Pada tahun 2010 produksi ikan tuna sirip kuning sebesar 444,952 ton, ikan tuna mata besar sebesar 979,189 ton, ikan tuna albakor sebesar 122,671 ton. Pada tahun 2019 produksi ikan tuna sirip kuning sebesar 617,992 ton, ikan tuna mata besar sebesar 240,487 ton, ikan tuna albakor sebesar 233,133 ton. Produktivitas tertinggi terjadi pada ikan tuna sirip kuning tahun 2014 dengan nilai LPUE sebesar 6,09 dengan produksi sebesar  2,448,171 ton dengan jumlah effort 402. Produktivitas mengalami fluktuasi setiap tahunnya.

Detecting and forecasting complex nonlinear dynamics in spatially structured catch-per-unit-effort time series for North Pacific albacore (Thunnus alalunga)

2011 ◽  
Vol 68 (3) ◽  
pp. 400-412 ◽  
Author(s):  
Sarah M. Glaser ◽  
Hao Ye ◽  
Mark Maunder ◽  
Alec MacCall ◽  
Michael Fogarty ◽  
...  
Keyword(s):  
Nonlinear Dynamics ◽  
Time Series ◽  
North Pacific ◽  
Stock Assessment ◽  
North Pacific Ocean ◽  
Catch Per Unit Effort ◽  
Data Set ◽  
Unit Effort ◽  
Thunnus Alalunga ◽  
Low Dimensional

The presence of complex, nonlinear dynamics in fish populations, and uncertainty in the structure (functional form) of those dynamics, pose challenges to the accuracy of forecasts produced by traditional stock assessment models. We describe two nonlinear forecasting models that test for the hallmarks of complex behavior, avoid problems of structural uncertainty, and produce good forecasts of catch-per-unit-effort (CPUE) time series in both standardized and nominal (unprocessed) form. We analyze a spatially extensive, 40-year-long data set of annual CPUE time series of North Pacific albacore ( Thunnus alalunga ) from 1° × 1° cells from the eastern North Pacific Ocean. The use of spatially structured data in compositing techniques improves out-of-sample forecasts of CPUE and overcomes difficulties commonly encountered when using short, incomplete time series. These CPUE series display low-dimensional, nonlinear structure and significant predictability. Such characteristics have important implications for industry efficiency in terms of future planning and can inform formal stock assessments used for the management of fisheries.

Eels at the Edge: Science, Status, and Conservation Concerns

2009 ◽  
Keyword(s):  
New Zealand ◽  
Management System ◽  
Stock Assessment ◽  
Catch Per Unit Effort ◽  
Commercial Catch ◽  
The North ◽  
Anguilla Australis ◽  
Unit Effort ◽  
Access Rights ◽  
Quota Management

<em>Abstract.</em>—The New Zealand eel fishery comprises two species, the shortfin eel <em>Anguilla australis </em>and the New Zealand longfin eel <em>A. dieffenbachii</em>. A third species, the speckled longfin eel <em>A. reinhardtii</em>, is present in small numbers in some areas. Major fisheries in New Zealand are managed under the Quota Management System. Individual transferable quotas are set as a proportion of an annual total allowable commercial catch. The Quota Management System was introduced into the South Island eel fishery on 1 October 2000 and the North Island fishery on 1 October 2004. Freshwater eels have particular significance for customary Maori. Management policies allow for customary take and the granting of commercial access rights on introduction into the Quota Management System. Eel catches have remained relatively constant since the early 1970s. The average annual catch from 1989–1990 to 2001–2002 (fishing year) was 1,313 mt. Catch per unit effort remained constant from 1983 to 1989 and reduced from 1990 to 1999. Statistically significant declines in catch per unit effort for New Zealand longfin eel were found in some areas over the latter period. For management, an annual stock-assessment process provides an update on stock status.

scholarly journals Analysis of juvenile North Atlantic albacore (Thunnus alalunga) catch per unit effort by surface gears in relation to environmental variables

2005 ◽  
Vol 62 (7) ◽  
pp. 1475-1482 ◽  
Author(s):  
Nicolas Goñi ◽  
Haritz Arrizabalaga
Keyword(s):  
North Atlantic ◽  
Environmental Variables ◽  
Negative Relationship ◽  
Generalized Least Squares ◽  
Catch Per Unit Effort ◽  
Seasonal Thermocline ◽  
Unit Effort ◽  
Negative Effect ◽  
Thunnus Alalunga ◽  
Age Structured

Abstract The relationship between the catch per unit effort (cpue) of trolling and baitboat fisheries targeting juvenile North Atlantic albacore (Thunnus alalunga, Bonnaterre, 1788) and several environmental variables was studied. A multiple linear regression and a generalized least squares model (GLS) showed a significant negative relationship between age 2 albacore trolling and baitboat cpue, and the average agitation of the sea and the duration of insolation. No clear relationship was found between the juvenile albacore cpue and sea surface temperature, precipitation, and NAO or Gulf Stream Index. Underlying processes that could explain the negative effect of agitation and insolation are discussed, especially relating to the habitat of age 2 albacore above the seasonal thermocline. Results highlight the necessity of considering environmental variables in the standardization of albacore cpue series used for calibrating age-structured stock assessments.

Age and growth of North Pacific albacore (Thunnus alalunga): Implications for stock assessment

2013 ◽  
Vol 147 ◽  
pp. 55-62 ◽  
Author(s):  
R.J. David Wells ◽  
Suzanne Kohin ◽  
Steven L.H. Teo ◽  
Owyn E. Snodgrass ◽  
Koji Uosaki
Keyword(s):  
North Pacific ◽  
Stock Assessment ◽  
Age And Growth ◽  
Thunnus Alalunga

scholarly journals BEBERAPA PARAMETER POPULASI IKAN PEDANG (Xiphias gladius) DI SAMUDERA HINDIA BAGIAN TIMUR

2017 ◽  
Vol 8 (2) ◽  
pp. 117
Author(s):  
Bram Setyadji ◽  
I Wayan Arthana ◽  
I Wayan Kasa
Keyword(s):  
Indian Ocean ◽  
Stock Assessment ◽  
Total Mortality ◽  
Growth Parameter ◽  
Assessment Model ◽  
Eastern Indian Ocean ◽  
Optimum Level ◽  
Xiphias Gladius ◽  
Longline Fisheries ◽  
Tuna Longline

Komposisi hasil tangkapan ikan berparuh (Istiophoridae dan Xiphiidae) menduduki peringkat kedua terbesar setelah tuna (Thunnus sp.) pada perikanan rawai tuna. Sekitar 90% jenis ikan berparuh yang di daratkan didominasi oleh ikan pedang (Xiphias gladius), yang mana merupakan hasil tangkap sampingan dari perikanan rawai tuna, terutama di Samudera Hindia bagian timur. Meskipun dikategorikan sebagai ikan dengan nilai ekonomis tinggi, akan tetapi studi mengenai parameter populasi untuk spesies ini masih terbatas, terutama di Indonesia. Penelitian ini bertujuan untuk menduga parameter pertumbuhan, laju mortalitas dan laju ekploitasi ikan pedang berdasarkan data ukuran panjang. Model pengkajian stok menggunakan data frekuensi panjang dipilih karena ketersediaan dan kemudahan pengambilan data tersebut dibandingkan dengan metode lainnya. Penelitian ini menggunakan data pemantau ilmiah tahun 2005 sampai dengan 2014 dan data pengamatan harian pendaratan tuna dan sejenisnya tahun 2002 sampai dengan 2014 di Samudera Hindia. Hasil penelitian menunjukkan pertumbuhan ikan pedang relatif cepat, terutama pada awal masa pertumbuhan dengan nilai K = 0,12/tahun, t0 = -0,76025 tahun dan L = 302,4 cmFL. Nilai F (0,28/tahun) sedikit lebih besar daripada nilai M (0,24/tahun), yang berarti kematian ikan pedang lebih banyak disebabkan oleh penangkapan. Nilai E sebesar 0,55 mengindikasikan bahwa ikan pedang yang tertangkap oleh armada rawai tuna di Samudera Hindia berada pada kondisi optimum. Billfishes (Istiophoridae and Xiphiidae) are the second largest catch in tuna longline fisheries. About 90% of billfishes landed dominated by swordfish (Xiphias gladius) which was a by-catch from tuna longline fisheries, especially in eastern Indian Ocean. Despite of its high economic value, study on stock assessment for this species is limited, especially in Indonesia. The catch-at-size based stock assessment model was applied, to its availability and ease on collecting the data. The Objectives of this study are to estimate growth parameter, mortality rate and exploitation rate based on catch-at-size data. The primary data was obtained from scientific observer program from 2005 to 2014 and port sampling data from 2002 to 2014. The result showed that swordfish were relatively fast growth, especially on their early age (K = 0.12/year) with t0 estimated around -0.76 year and Linf about 302.4 cmLJFL. The estimated of total mortality (Z), natural mortality (M) and fishing mortality (F) from the model were 0.52/year, 0.24/year and 0.28/year respectively. The explitation rate of swordfish in the eastern Indian Ocean is on optimum level (E=0.55).

Impacts of spatial scales of fisheries and environmental data on catch per unit effort standardisation

2009 ◽  
Vol 60 (12) ◽  
pp. 1273 ◽  
Author(s):  
Siquan Tian ◽  
Yong Chen ◽  
Xinjun Chen ◽  
Liuxiong Xu ◽  
Xiaojie Dai
Keyword(s):  
Spatial Scale ◽  
Stock Assessment ◽  
Spatial Scales ◽  
Additive Models ◽  
Environmental Data ◽  
Catch Per Unit Effort ◽  
The North ◽  
Unit Effort ◽  
Data Collection And Analysis ◽  
North Western

Spatial scale is an important factor that needs to be considered in data collection and analysis in ecological studies. Studies focusing on the quantitative evaluation of impacts of spatial scales are, however, limited in fisheries. Using the Chinese squid-jigging fishery in the north-western Pacific Ocean as an example, we evaluated impacts of spatial scale used in grouping fisheries and environmental data on the standardisation of fisheries catch per unit effort (CPUE). We developed 18 scenarios of different spatial scales with a combination of three latitudinal levels (0.5°, 1° and 2°) and six longitudinal levels (0.5°, 1°, 2°, 3°, 4° and 5°) to aggregate the data. We then applied generalised additive models to analyse the 18 scenarios of data for the CPUE standardisation, and quantified differences among the scenarios. This study shows that longitudinal and latitudinal spatial scale and size of the spatial area for data aggregation can greatly influence the standardisation of CPUE. We recommend that similar studies be undertaken whenever possible to evaluate the roles of spatial scales and to identify the optimal spatial scale for data aggregations in the standardisation of CPUE and fisheries stock assessment.

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