the population biology of the thornback ray, raja clavata in caernarfon bay, north wales

2005 ◽  
Vol 85 (5) ◽  
pp. 1089-1094 ◽  
Author(s):  
j.m. whittamore ◽  
i.d. mccarthy
Keyword(s):  
Population Biology ◽  
Allee Effect ◽  
Growth Parameters ◽  
Total Mortality ◽  
Von Bertalanffy ◽  
Recruitment Failure ◽  
North Wales ◽  
Thornback Ray ◽  
Raja Clavata ◽  
The Status

amid concern about the status of skates and rays in welsh waters the present work set out to provide up-to-date information on the population biology of raja clavata in caernarfon bay. the von bertalanffy growth parameters were l∞=100.9 cm, k=0.18 y−1 and t0=−0.95 y for males; and l∞=117.6 cm, k=0.16 y−1 and t0=−0.7 y for females. male r. clavata reached 50% maturity at 58.8 cm and 3.9 y, which was smaller and younger than females (l50 and a50 were 70.5 cm and 5.3 y, respectively). although previously over-exploited, the present estimate of total mortality (z) was 0.48–0.49 y−1 which, in terms of replacement mortality (calculated as 0.7 y−1), suggests no immediate prospect of recruitment failure for r. clavata in caernarfon bay. the potential for the recovery of a depleted population is discussed in relation to the allee effect.

scholarly journals Morphological abnormality in thornback ray Raja clavata in the Irish Sea

2021 ◽  
Author(s):  
L. J. Clarke
Keyword(s):  
Irish Sea ◽  
Beam Trawl ◽  
Morphological Abnormality ◽  
Free Swimming ◽  
Pectoral Fins ◽  
North Wales ◽  
Head Section ◽  
Thornback Ray ◽  
Raja Clavata ◽  
The Irish Sea

AbstractA free-swimming thornback ray Raja clavata specimen demonstrating significant morphological abnormality is reported, captured by beam trawl in the Irish Sea off north Wales, UK. The anterior sections of both pectoral fins were separated from the head section for a length of approximately 140 mm extending from the rostrum tip to a point posterior of the spiracles, along with abnormal morphology of the gill slits. This phenomenon has been observed elsewhere but is the first documented example of this abnormality in the eastern Irish Sea, despite widespread targeting of the species across the region by commercial and recreational fishers. Possible causes and consequences of the observed abnormality are discussed.

Fifty years of tagging skates (Rajidae): using mark-recapture data to evaluate stock units

2019 ◽  
Vol 100 (1) ◽  
pp. 121-131 ◽  
Author(s):  
C. Bird ◽  
G. J. Burt ◽  
N. Hampton ◽  
S. R. McCully Phillips ◽  
J. R. Ellis
Keyword(s):  
Northern Ireland ◽  
Uncertain Data ◽  
Irish Sea ◽  
Mark Recapture ◽  
Straight Line ◽  
Thornback Ray ◽  
Raja Clavata ◽  
Elasmobranch Fish ◽  
The Status ◽  
The Irish Sea

AbstractDespite increased focus on ascertaining the status of elasmobranch fish, the stock units for many species are uncertain. Data from mark-recapture tagging studies undertaken from 1959–2017 were analysed for 13 batoid species. Data were most comprehensive for skates (Rajidae), with 22,374 released and 3342 (14.9%) returned. Most data related to thornback ray Raja clavata, blonde ray R. brachyura and spotted ray R. montagui. Tags were generally returned from areas less than 50 km from their release, and usually from the ICES Division in which they were released. However, straight-line distances travelled of up to 910 km (R. brachyura) and 772 km (R. clavata) were recorded, highlighting that individual skates are capable of longer-distance movements. The maximum time at liberty was 16.6 years (R. clavata). Whilst mark-recapture data indicated that the current stock units used by ICES are broadly appropriate, southward movements of several skate species tagged off Northern Ireland (Division 6.a) to the Irish Sea (Division 7.a) were observed. In contrast, skates tagged in the Irish Sea and Bristol Channel (Division 7.f) generally remained in that area, with only occasional recaptures from Division 6.a.

scholarly journals Model Pertumbuhan Dan Status Sumberdaya Panulirus homarus Di Cilacap, Jawa Tengah

2019 ◽  
Vol 8 (1) ◽  
pp. 85-93
Author(s):  
Maulvi Didit Baskoro ◽  
Edi Wibowo Kushartono ◽  
Irwani Irwani
Keyword(s):  
Growth Model ◽  
Growth Parameters ◽  
Spiny Lobster ◽  
Growth Function ◽  
Fishing Effort ◽  
Maximum Sustainable Yield ◽  
Sustainable Yield ◽  
Von Bertalanffy ◽  
Von Bertalanffy Growth Function ◽  
The Status

Lobster pasir (Panulirus homarus) merupakan salah satu jenis lobster yang banyak di temukan di perairan Indonesia. Penelitian ini dilaksanakan pada bulan November 2017 sampai bulan Februari 2018 dengan lokasi pengambilan sampel di Pelabuhan Perikanan Samudra Cilacap (PPSC), di Perairan Cilacap Penelitian ini melihat bagaimana model pertumbuhan, dan status sumberdaya, mulai dari Von Bertalanffy, CPUE dan MSY. Estimasi parameter pertumbuhan lobster pasir (Panulirus homarus) dihitung dengan aplikasi Fisat II. Didapatkan hasil model pertumbuhan lobster pasir ( L∞ = 93.66 cm , K = 0.780 dan t0 -1.0950 mm). Hasil CPUE didapatkan persamaan, nilai linier sebesar  y = -0.0002 + 0.0965 x, nilai R2= 0,09443 untuk data lima tahun ke belakang terhitung dari 2012 sampai 2016 dalam upaya penangkapan (Panulirus sp.). Analisa Maximum sustainable yield (MSY) di lakukan untuk mengetahui besarnya potensi lestari Panulirus sp. dengan registrasi linier y-0.0002x + 0.965. Pendugaan MSY dan upaya penangkapan Foptimum diperoleh dengan 2412 trip dan nilai MSY 1164.031. Produksi Panulirus sp. di tahun 2016 – 2017 di Perairan Cilacap mengalami kenaikan, pada tahun 2016 terjadi kenaikan di bulan Februari, Maret, April dan Desember. Sedangakan pada tahun 2017 terjadi kenaikan di bulan Maret dan Oktober. Kenaikan ini dikarenakan musim lobster berada di bulan Oktober hingga Februari. Perubahan iklim dan penangkapan yang melebihi batas akan berpengaruh terhadap ukuran dan stok Panulirus sp. di alam. The Spiny lobster (Panulirus homarus) is one species of lobster that is widely found in Indonesian. This research was conducted on November 2017 until February 2018 the sample locations at the Cilacap (PPSC), which observed  the growth of models, and the status of resources, regretion Von Bertalanffy Growth function CPUE and MSY. The estimated growth parameters of sand lobster (Panulirus homarus) were  calculated using Fisat II application. The results of the spiny lobster  growth  model were obtained (L∞ = 93.66 cm, K = 0.780 and 0 -1.0950 mm). The CPUE results were obtained equations, linear values of y = -0.0002 + 0.0965 x for five years data from 2012 to 2016 . The Maximum Sustainable Yield (MSY) analysis was carried out to determine the magnitude of the sustainable potential of Panulirus sp. within linear  y-0.0002x + 0.965. The MSY values 1164,031 estimation and (Foptimum) fishing effort were 2.412 trips and MSY values 1164,031. The  production of Panulirus sp. start from  2016 to 2017 in the Cilacap has increased, the fact in 2016 there was an increase on February, March, April and December, while in 2017 there was an increase on March and October. So that the increase due to the lobster season being in October to February.  In addition, climate alteration and capture exceed the effect of  size and stock of Panulirus sp.

scholarly journals DINAMIKA POPULASI DAN STATUS PEMANFAATAN UDANG TIGER (Penaeus monodon Fabricius 1798) DI PERAIRAN TARAKAN, KALIMANTAN UTARA

2020 ◽  
Vol 12 (1) ◽  
pp. 11
Author(s):  
Umi Chodrijah ◽  
Ria Faizah ◽  
Tirta Danu
Keyword(s):  
Growth Parameters ◽  
Penaeus Monodon ◽  
Total Mortality ◽  
Optimal Level ◽  
Survey Method ◽  
Von Bertalanffy ◽  
Population Parameters ◽  
Exploitation Rate ◽  
Tiger Prawn ◽  
Exploitation Status

Udang tiger (Penaeus monodon Fabricius 1798) di Tarakan merupakan salah satu komoditas ekspor dan sudah dimanfaatkan cukup lama serta memiliki permintaan dan nilai ekonomis yang tinggi. Penelitian dinamika populasi dan status pemanfaatan udang tiger di perairan Tarakan dan sekitarnya dilakukan untuk mengevaluasi status stok sumberdaya udang agar pengelolaannya dapat berkelanjutan. Penelitian ini dilakukan pada bulan Januari-November 2016 dengan metode survey. Status pemanfaatan diduga berdasarkan laju eksploitasi dan estimasi rasio pemijahan berbasis data panjang (LB-SPR). Hasil pengamatan menunjukkan udang tiger memiliki panjang karapas asimptotik (CL∞) sebesar 65,45 mm, laju pertumbuhan (K) sebesar 1,55 /tahun dan nilai t0 sebesar -0,20/tahun sehingga diperoleh persamaan pertumbuhan Von Bertalanffy CLt = 65,45(1 – e-1,55(t+-0,20)). Laju mortalitas total (Z) sebesar 6,56/ tahun, mortalitas alami (M) sebesar 1,95/tahun, mortalitas penangkapan (F) sebesar 4,62/tahun dan tingkat pemanfaatan (E) sebesar 0,70 /tahun. Tingkat pemanfaatan udang tiger di perairan Tarakan lebih besar dari tingkat pemanfaatan optimal sehingga disarankan untuk menurunkan upaya sebesar 40% dari upaya saat ini.Tiger prawn (Penaeus monodon Fabricius 1798) was one of the export commodity and had been exploited for longtime ago so it was necessary to study about its population parameters and exploitation status for its sustainable management. This research aimed to study about the population parameters and exploitation status of tiger prawn. The research were carried out from January to November 2016 using survey method and the enumeration programme. The growth parameters were based on the Modal Progression Analysis. Exploitation status was estimated based on length based spawning potential ratio (LB-SPR). The results showed that the asymptotic length (CL∞) was 65.45 mm, the growth rate (K) was 1.55 /year and = t0 was -0,20/year so Von Bertalanffy Growth Model was CLt = 65.45(1 - e -1.55(t+-0.20)). Total mortality (Z) was 6.56/years, natural mortality was 1.95/years and fishing mortality was 4.62/years and the highest recruitment of tiger prawns occured in May. The exploitation rate (E) was 0,70/years. The exploitation rate now is higher then the optimal level so it is recommended to reduce 40% of the current efforts.

The population dynamics of the red porgy Pagrus pagrus along southern Brazil, before its fishery collapse in the 1980s: a baseline study

2020 ◽  
Vol 33 ◽  
pp. 10
Author(s):  
Manuel Haimovici ◽  
Eidi Kikuchi ◽  
Luís Gustavo Cardoso ◽  
Rubens Moralles
Keyword(s):  
Growth Parameters ◽  
Total Mortality ◽  
Von Bertalanffy ◽  
Southern Brazil ◽  
Red Porgy ◽  
Exploitation Rate ◽  
Males And Females ◽  
Intense Exploitation ◽  
Pagrus Pagrus ◽  
Fishery Collapse

The intense exploitation since 1972 of the formerly only slightly exploited protogynous hermaphroditic fish Pagrus pagrus (L.) in southern Brazil has led in less than a decade to the collapse of the fishery, with no recovery four decades later. In this study we analized the age structure, growth, reproduction and mortality of the species were studied based on samples collected from 1976 to 1985 to provide a baseline before the onset of overexploitation. Maximum estimated ages were 21 and 26 years based on scale and otolith readings, respectively. Mean total length (TL) at age did not differ between males and females, while hermaphrodites were smaller. The von Bertalanffy growth coefficients for all fish (immature, females, hermaphrodites and males) were L∞ = 447 mm, k = 0.204 and t0 = −1.134 yr. Change in growth was observed during the study period. Females were dominant at all sizes, hermaphrodites were only present up to intermediate sizes, and males, despite being infrequent at small sizes, made up over 40% among the larger specimen (TL > 400 mm). Spawning took place mainly in late spring and condition factors were lower after spawning. Natural mortality was estimated as M = 0.173 yr−1 based on the von Bertalanffy growth parameters. Total mortality (Z) and exploitation rate (E) estimated from catch curves of fully recruited red porgies aged five to ten years increased from 0.24 yr−1 and 28% before 1973 to 0.49 yr−1 and 63% in the following years. Two distinct scale and otolith patterns, one with well-marked annuli and another with faint or absent annuli, suggested that the red porgy stock off southern Brazil might not be homogeneous and may include subpopulations that do not fully mix.

scholarly journals Growth, Mortality, and Exploitation Rate of Penaeus merguensis in the North Coast of Central Java, Indonesia

2019 ◽  
Vol 23 (4) ◽  
pp. 207
Author(s):  
Suradi Wijaya Saputra ◽  
Anhar Solichin ◽  
Wiwiet Teguh Taufani
Keyword(s):  
Mortality Rate ◽  
Population Biology ◽  
Carapace Length ◽  
Growth Parameters ◽  
Total Mortality ◽  
Survey Method ◽  
North Coast ◽  
Optimum Level ◽  
Central Java ◽  
Exploitation Rate

One of the most-caught shrimp in north coast of Central Java is Penaeus merguiensis. However, little is known on the population biology of the organisms. This study was aimed to investigate length-weight relationship, growth, length at first capture (Lc50), mortality rate, and exploitation rate of P. merguiensis in Western part of Central Java’s northern coastal waters. The study was conducted from May 2016 to July 2017 using survey method. Samples were taken for 15 times (month) from 9 coastal fishing ports. The result shows that the relationship of the carapace length and weight is negative allometry. The growth parameters of CL∞ and K were 52.5mm and 1.3 y-1 (male) and 57.25mm and 1.2 y-1 (female). Total mortality rate (Z), natural mortality rate (M), and fishing mortality rate (F) were 4.51 y-1, 1.86 y-1 and 2.65 y-1 (male), and 5.36 y-1, 1.72 y-1, and 3.64 y-1 (female), respectively. The exploitation rate (E) of male banana shrimp was 0.59, and for female shrimp was 0.68. The result shows that the exploitation level has exceeded the optimum level (E>0.5). Recruitment of P. merguiensis may occur the whole year, but it peaks were in March and August (male), April and August (female). Carapace length of first captured (CLc50) was 20.63mm (male) and 18.28mm (female). It means that the sized of captured P. merguiensis is less than the size of first mature (CLm50) or growth overfishing and as a result, disrupting the availability of adult shrimp. The condition occurs due to the size of cod-end mesh measured 0.75inc.

scholarly journals Analisis Stok dan Tingkat Pemanfaatan Sumberdaya Ikan Lemadang (Coryphaena hippurus) Berdasarkan Data di Pelabuhan Perikanan Samudera Cilacap

2020 ◽  
Vol 23 (3) ◽  
pp. 362-372
Author(s):  
Cita Susila ◽  
Abdul Ghofar ◽  
Suradi Wijaya Saputra
Keyword(s):  
Growth Parameters ◽  
Total Mortality ◽  
Maximum Sustainable Yield ◽  
Analytical Models ◽  
Fish Length ◽  
Growth Equation ◽  
Von Bertalanffy ◽  
Relationship Analysis ◽  
Coryphaena Hippurus ◽  
Tuna Fisheries

Dolphinfish fish is one of the commodities of Indonesian waters, which is a bycatch of tuna fisheries. Lemadang fish are under considerable catching pressure and tend to increase, thus endangering their sustainability. The purpose of the study was to find out the length of first caught (Lc50%), growth parameters, mortality rate, MSY value, optimum trip (f) and lemadang fish exploitation rate. The data collected are fish length (cmFL), fish weight (kg), fish production, and fishing efforts. The data were collected once every 2 weeks during November 2019 until January 2020. The results of the study is the size of fish ranged from 41 – 125 cmFL and  length at first capture (Lc50%) 75 cmFL. The long-weight relationship analysis obtained equation W=0,0000378*L2,363 with negative allometric growth pattern. The growth equation von Bertalanffy obtained Lt = L∞(1-e-1.8(t+0,343)). The total mortality 8,54 year-1 the rate of exploitation amounted to 0,8 with the peak of recruitment in August. The estimated value of MSY of Dolphinfish was 121.570 kg/year with optimum effort of 571 trip/year. The estimated value of Dolphinfish sustainable potential is 121,570 kg/year, with optimum efforts of 571 trips/year. Dolphinfish production since 2011 has exceeded its maximum sustainable yield (MSY). Utilization of Dolphinfish fish resources has been overfishing, both based on analysis of analytical models and production surplus models. Ikan Lemadang merupakan salah satu komoditi dari perairan Indonesia, yang merupakan bycatch dari perikanan tuna. Ikan Lemadang mengalami tekanan penangkapan yang cukup tinggi dan cenderung meningkat, sehingga dapat membahayakan kelestariannya. Tujuan dari penelitian adalah mengetahui ukuran pertama kali tertangkap, parameter pertumbuhan, laju mortalitas, nilai MSY, trip (f) optimum, dan tingkat eksploitasi ikan Lemadang. Data yang dikumpulkan adalah panjang cagak ikan (cmFL) dan bobot ikan (kg), volume tangkapan dan upaya penangkapan (trip), produksi ikan dan trip penangkapan. Pengambilan data dilakukan 2(dua) minggu sekali selama bulan November 2019 hingga Januari 2020. Hasil penelitian diperoleh ukuran panjang ikan berkisar 41 – 125 cmFL, dan ukuran pertama kali tertangkap (Lc50%) 75 cmFL. Persamaan hubungan panjang-bobot didapatkan W=0,0000378*L2,363,dan sifat pertumbuhan alometrik negatif. Persamaan pertumbuhan von Bertalanffy ikan Lemadang didapatkan Lt = L¥ (1-e-1,8(t+0,343)). Puncak rekrutmen terjadi pada bulan Agustus. Laju mortalitas total (Z) adalah 8,54 per tahun, mortalitas penangkapan (F) = 6,81/tahun, dan tingkat eksploitasi (E=F/M) sebesar 0,8. Nilai dugaan potensi lestari ikan Lemadang sebesar 121.570 kg/tahun, dengan upaya optimum sebesar 571 trip/tahun. Produksi ikan Lemadang sejak tahun 2011 sudah melebihi tingkat produksi maksimum lestari (MSY)-nya. Pemanfaatan sumber daya ikan Lemadang sudah overfishing. baik berdasarkan analisis model analitik maupun model surplus produksi.

scholarly journals Age, growth, mortality, and exploitation rate of blueline snapper, Lutjanus coeruleolineatus (Actinopterygii: Perciformes: Lutjanidae), from Dhofar Governorate, Sultanate of Oman

2021 ◽  
Vol 51 (2) ◽  
pp. 159-166
Author(s):  
Dawood Almamari ◽  
Said Rabia ◽  
Joo Myun Park ◽  
Laith A. Jawad
Keyword(s):  
Fishery Management ◽  
Growth Parameters ◽  
Total Mortality ◽  
Natural Mortality ◽  
Von Bertalanffy ◽  
Fishing Mortality ◽  
Sultanate Of Oman ◽  
Commercial Fish ◽  
Exploitation Rate ◽  
Reported Study

The blueline snapper, Lutjanus coeruleolineatus (Rüppell, 1838), is a significant commercial fish species harvested from the traditional fishery in the Sultanate of Oman. Deficient data on this species, however, make the management strategies challenging, especially in fisheries ecology. A total of 978 specimens were obtained from Dhofar Governorate off the coast of the Arabian Sea during the period between February 2015 and March 2016. In total, 296 sectioned otoliths were analyzed and growth was estimated from non-seasonal growth by using von Bertalanffy method. The parameters of von Bertalanffy growth function, total mortality (Z), natural mortality (M), fishing mortality (F), and exploitation rate (E) were determined and compared with those for Lutjanidae fishes elsewhere. The age structure of male fishes was between 1 and 14 years for males while the age of females ranged from 1 to 18 years. Growth rate (K) was 0.21 y–1 and 0.16 y–1 for males and females, respectively. The hypothetical length of female (L∞ = 46 cm) was relatively higher than that of male (L∞ = 42 cm). The natural mortality (M) was 0.296, total mortality (Z) was 0.372, fishing mortality was 0.076, and exploitation rate (E) was estimated as 0.2. The presently reported study is conducted to examine this fish in relation to growth parameters by analyzing otolith structure. The results of the presently reported study will contribute towards planning the regional fishery management policies in Oman.

scholarly journals Yield-per-Recruit and Relative Mean Biomass Estimates, and their Management Consequences, to the Penaeus Indicus Fishery in the Gulf of Masirah

1996 ◽  
Vol 1 ◽  
pp. 51
Author(s):  
M. S. M. Siddeek ◽  
R. Mohan ◽  
D. W. Johnson
Keyword(s):  
Growth Parameters ◽  
Total Mortality ◽  
High Yield ◽  
Average Weight ◽  
Natural Mortality ◽  
Von Bertalanffy ◽  
Fishing Season ◽  
Penaeus Indicus ◽  
Length Data ◽  
Yield Per Recruit

The von Bertalanffy growth parameters estimated based on the 1990/91 carapace length data of Penaeus indicus  from the Gulf of Masirah, Oman were used to calculate total mortality, yield-per-recruit ( i.e. average weight of a shrimp from a cohort under a given fishing pattern) , and relative mean biomass ( i.e. exploited cohort biomass over un-exploited cohort biomass) for the population sampled. The instantaneous total mortality coefficient value indicated under exploitation in 1990/91. When different fishing seasons scenarios were considered with the current total mortality level but with a range of natural mortality values, high yield, per recruit and relative mean biomass values were shown for October-April and November-April fishing seasons. The fishing season is currently late August to end of April. Thus, a one to two-month delay in the fishing season appears to be beneficial to this fishery.

scholarly journals PARAMETER POPULASI DAN POLA REKRUITMEN IKAN TONGKOL LISONG (Auxis rochei Risso, 1810) DI PERAIRAN BARAT SUMATERA

2015 ◽  
Vol 7 (3) ◽  
pp. 129
Author(s):  
Tegoeh Noegroho ◽  
Umi Chodrijah
Keyword(s):  
Mortality Rate ◽  
Frequency Analysis ◽  
Growth Parameters ◽  
Fork Length ◽  
Total Mortality ◽  
Von Bertalanffy ◽  
Population Parameters ◽  
Length Frequency ◽  
Exploitation Rate ◽  
Length Frequency Analysis

Perikanan neritik tuna di perairan Barat Sumatera berkembang pesat beberapa dekade terakhir ini. Sementara belum banyak diperoleh hasil penelitian tentang populasi ikan tongkol lisong (Auxis rochei). Penelitian tentang parameter populasi dan pola rekruitmen ikan tongkol lisong dilakukan pada bulan Februari-Desember 2013 di beberapa lokasi pendaratan ikan di Barat Sumatera. Tujuan penelitian ini adalah untuk memperoleh laju pertumbuhan, panjang asimptotik, laju kematian, laju eksploitasi, dan pola rekruitmen ikan tongkol lisong (Auxis rochei). Estimasi parameter populasi menggunakan model analitik berdasarkan program “Electronic Length Frequency Analysis (ELEFAN 1)”. Data frekuensi panjang dikumpulkan berkesinambungan di beberapa tempat pendaratan utama. Hasil penelitian menunjukkan panjang cagak ikan tongkol lisong yang tertangkap berada pada kisaran 11-42 cmFL. Parameter pertumbuhan Von Bertalanffy diperoleh nilai laju pertumbuhan (K) sebesar 0,54/tahun, panjang asimptotik (L ) sebesar 43,5 cm FL, dan umur ikan pada saat panjang ke-0 (-t0) sebesar -0,076/tahun. Laju mortalitas total (Z) sebesar 1,96/tahun. Laju kematian karena penangkapan (F) sebesar ,07/tahun, dan laju kematian alami (M) 0,89/tahun. Laju eksploitasi (E) tongkol lisong di Barat Sumatera adalah 0,49/tahun atau berada pada tingkat eksploitasi moderat. Pola rekrutmen tongkol lisong terjadi dua kali dalam setahunnya, yaitu mencapai puncak pada bulan Maret dan Juni.Neritic tuna fishery in theWest Sumatra waters was developed very intensively in the captured.Meanwhile, study population of bullet tuna (Auxis rochei) in those are still limited. Research in population parameters and recruitmen pattern of bullet tuna has been conducted in February-December 2013 based on several landing place inWest Sumatra. The aim of this study is to obtain asymptotic length, mortality rate, exploitation rate, and recruitment pattern of bullet tuna (Auxis rochei). Estimation of population parameters using an analytical model based on the program “Electronic Length Frequency Analysis (ELEFAN 1)”. Length frequency data collected continuously in themain landing places The results showed the fork length of bullet tuna was caught in the range 11-42 cm FL. Von Bertalanffy growth parameters obtained the growth rate value (K) of 0,54/year, asymptotic length (L ) of 43,5 cm FL, and fish age when the length to the-0 (-t0) of -0,076/year. Total mortality was 1,96/year. Fishing mortality rate (F) was 1,07/year and natural mortality rate (M) 0,89/year. The exploitation rate (E) of bullet tiuna in West Sumatra was 0,49 / year or are at a moderate level of exploitation. Recruitment patterns of bullet tuna happen twice in a year, which reached a peak in March and June.

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