scholarly journals First Assessment of the Thryssa vitrirostris (Engraulidae) Beach Seine Fishery in Northeastern Mozambique

J ◽  
2018 ◽  
Vol 1 (1) ◽  
pp. 116-132
Author(s):  
Bonifácio Manuessa ◽  
Eurico Morais ◽  
Teresa Cerveira Borges ◽  
Maria Teodósio ◽  
Francisco Leitão
Keyword(s):  
Standard Length ◽  
Growth Parameters ◽  
Mesh Size ◽  
Fishing Effort ◽  
Fishing Mortality ◽  
Beach Seine ◽  
Management Measures ◽  
Exploitation Rate ◽  
Exploitation Status ◽  
Sustainable Fishery

Monthly length-frequency data, from 2009 to 2014, was used to estimate the growth parameters, mortality, and spawning season, and to assess the exploitation status of Thryssa vitrirostris (Engraulidae) fisheries in Pebane. The von Bertalanffy asymptotic length (L∞) and growth rate (K) were 25.1 cm (standard length) and 0.41 per year (standard length), respectively. Two proxy recruitment peaks were found: the first peak of recruitment occurs from April to July, and the second recruitment peak from September to October. The total estimated mortality rates (Z), natural mortality (M), and fishing mortality (F) were Z = 1.31, M = 0.92, and F = 0.39. For the beach seine gear, the size at first catch of T. vitrirostris was Lc25 = 4.43 cm. The 50% retention size of the catch was Lc50 = 5.39 cm. The retention probability analyses revealed a large rate of juvenile fishing mortality (54.2%). The estimated exploitation rate (0.30) was below the maximum exploitation rate (0.48), and above the optimal sustainable exploitation rate (E50 = 0.28), evidencing a sustainable fishery. However, under such an exploitation regime, it is advised that a continuously monitoring-survey of T. vitrirostris is maintained. An increase in migration of fishermen has been recently recorded in Pebane, due to its rich fisheries, which can increase the fishing effort and the risk of overexploitation if management measures (such as mesh size increase) are not taken in advance.

scholarly journals ASPEK BIOLOGI DAN PARAMETER POPULASI UDANG JINGA (Metapenaeus affinis H. Milne Edwards, 1837) DI PERAIRAN KOTABARU, KALIMANTAN SELATAN

2017 ◽  
Vol 9 (1) ◽  
pp. 11
Author(s):  
Tirtadanu Tirtadanu ◽  
Suprapto Suprapto ◽  
Ali Suman
Keyword(s):  
Growth Parameters ◽  
Growth Function ◽  
Fishing Effort ◽  
Population Parameters ◽  
Male And Female ◽  
Management Measures ◽  
Exploitation Rate ◽  
Mean Size ◽  
Biological Aspects ◽  
The Mean

Udang jinga (Metapenaeus affinis H. Milne Edwards, 1837) merupakan salah satu jenis udang ekonomis penting yang diusahakan di perairan Kotabaru dan saat ini produksinya cenderung mengalami penurunan. Salah satu data dan informasi yang diperlukan dalam mengkaji tingkat pemanfaatan dan dasar pengelolaannya adalah aspek biologi dan parameter populasi. Penelitian ini bertujuan mengkaji aspek biologi dan parameter populasi udang jinga sebagai bahan kebijakan pengelolaan perikanan udang di perairan Kotabaru, Kalimantan Selatan. Penelitian dilakukan pada bulan Januari – November 2016 di perairan Kotabaru. Parameter pertumbuhan diestimasi berdasarkan pergeseran modus struktur ukuran panjang dengan metode ELEFAN I. Hasil penelitian menunjukkan rata-rata ukuran udang jinga (M. affinis) betina yang tertangkap adalah 23,6 ± 3,45 mmCL dengan modus ukuran 24 mmCL dan rata-rata ukuran udang jantan adalah 20,7 ± 2,9 mm dengan modus ukuran 18 mmCL. Nisbah kelamin udang jinga jantan dan betina adalah 1 : 2,5. Musim pemijahan udang jinga diduga berlangsung sepanjang tahun dan puncak pada bulan Maret. Ukuran rata-rata pertama kali tertangkap (Lc) udang lebih kecil dari ukuran rata-rata pertama kali matang gonad (Lm) (21,7 < 28,5 mm CL) sehingga sebagian besar udang tertangkap berukuran kecil dan belum memijah. Persamaan pertumbuhan udang jinga jantan  CL(t)=35,95(1-e-2.02(t+0,31) dan udang jinga betina CL(t)= 38,3(1-e-1,92(t+0,29)). Tingkat pemanfaatan udang (E) menunjukkan lebih tangkap (overfishing) yakni 0,70/tahun pada jantan dan 0,73/tahun pada betina. Dengan demikian disarankan untuk melakukan pengurangan upaya penangkapan sebesar 40% dan penutupan musim penangkapan di bulan Maret.The jinga shrimp (Metapenaeus affinis H. Milne Edwards, 1837) was one of important commodity that was exploited in Kotabaru Waters, yet the production tend to be declined recently. The data and information on biological aspects and population parameters are needed to investigate the exploitation level and the basis of management measures. This research aims to investigate the biological aspects and population parameters of jinga shrimp Kotabaru waters, South of Kalimantan. This research was conducted on January – November 2016. The growth parameters were estimated as movement of length frequency mode by ELEFAN I method. The results showed that the mean size of female jinga shrimp (M. affinis) was 23,6 ± 3,45 mm CL and the mode was 24 mmCL. While, the mean size of male jinga shrimp was 20,7 ± 2.9 mm CL and the mode was 18 mmCL. The sex ratio of male and female shrimp was 1 : 2,5 . Spawning season of jinga shrimp was estimated throughout the year and the peak was in March. The length at first captured (Lc) was shorter than length at first matured (Lm) (21,7 < 28,5 mm CL). That means most of the catches was immature. The growth function of male and female jinga shrimp were and, CL(t)=35,95(1-e-2.02(t+0,31) respectively and CL(t)= 38,3(1-e-1,92(t+0,29)). The exploitation rate (E) of male and female shrimp fishing were  0,70/year 0,73/year, respectively. The reduction of fishing effort needed by 40% of the actual combined with the temporal fishing closure March.

Simulations of the impact of different temporal and spatial allocations of fishing effort on fishing mortality in a lobster (Homarus americanus) fishery

2002 ◽  
Vol 59 (5) ◽  
pp. 899-909 ◽  
Author(s):  
Louise Gendron ◽  
Jean-Claude Brêthes
Keyword(s):  
Homarus Americanus ◽  
Fishing Effort ◽  
Fishing Mortality ◽  
Management Scenarios ◽  
Spatially Explicit Model ◽  
Offshore Area ◽  
Management Measures ◽  
Exploitation Rate ◽  
Temporal And Spatial ◽  
The Impact

A spatially explicit model is proposed to assess the impact on fishing mortality of modifying effort patterns for an American lobster (Homarus americanus) fishery. A two-box (offshore and inshore grounds) model is developed for the 1995 lobster fishery season in the Magdalen Islands (Quebec). It considers lobster migration and fisher's temporal and spatial effort dynamics to estimate within-season catchability patterns and exchange rates between the two spatial units. Different management scenarios are simulated: reducing nominal fishing effort and changing its temporal (season's length) and spatial (area closures) allocations. Catchability showed a strong temporal trend, being highest during the first 3 weeks and declining regularly afterwards. The model indicated a continuous migration toward the inshore during the fishing season and that a significant amount of biomass remained offshore. As a result, reducing fishing effort at the beginning of the season would have the greatest impact on exploitation rate. Allowing less effort in the offshore area would also reduce the exploitation rate significantly. Restricting effort to the inshore area, as it was 25 years ago, reduced substantially the exploitation rate. This model represents the first attempt to analyze in-season fishery dynamics and should be useful to further assess the impact of management measures.

scholarly journals ESTIMATION OF GROWTH, MORTALITY, AND EXPLOITATION STATUS OF NURSE TETRA (Brycinus nurse) AND TRUE BIG SCALE TETRA (Brycinus macrolepidotus) (FAMILY: ALESTIDAE) FROM THE NEW CALABAR RIVER, NIGERIA

2020 ◽  
Vol 25 (2) ◽  
pp. 113
Author(s):  
Olaniyi Alaba Olopade ◽  
Henry Eyina Dienye ◽  
Uzoma C Nworgu
Keyword(s):  
Growth Parameters ◽  
B Value ◽  
Fishing Effort ◽  
Growth Patterns ◽  
Allowable Limit ◽  
Growth Coefficient ◽  
Fish Samples ◽  
Landing Sites ◽  
Exploitation Rate ◽  
Exploitation Status

This study aimed to determine the growth patterns, mortality, and exploitation status of two species of Alestidae in the New Calabar River, Nigeria. For this purpose, fish samples were collected monthly from three landing sites from the local fishermen using gill nets (mesh sizes: 15-25mm), beach seine (mesh sizes: 2.3-10mm), and cast nets (mesh sizes: 15 -25mm). The length-weight relationship revealed exponent “b” value for Brycinus nurse was 3.54 and 3.21 for Brycinus macrolepidotus while the condition factors were 1.08 and 1.02 for Brycinus nurse and Brycinus macrolepidotus respectively. The growth parameters of Brycinus nurse asymptotic length (L) and growth coefficient (K) were 24.46 cm and 0.52 yr-1, respectively, while those for Brycinus macrolepidotus L was 28.88 cm and K was 0.22 yr-1. The reproductive load (L50/L) ratio was found to be 0.59 and 0.61 for B. nurse and B. macrolepidotus, respectively. Exploitation rate (E) for B. nurse was 0.26 and 0.11 for B. macrolepidotus while length-at-first capture (Lc) was 14.49 cm for B. nurse and 17.64 cm for B. macrolepidotus. The natural mortality was greater than the fishing mortality for both species and Logistic regression of the probability of capture routine values recorded for B. nurse were higher than that of B. macrolepidotus. Maximum exploitation rate (Emax) was less than 0.5 for both B. nurse (0.41) and B. macrolepidotus (0.42). These values were close to the maximum allowable limit; therefore, the species may be unsustainable when fishery intensifies in the future. To ensure sustainable exploitation of the two Alestid species in the area, fishing effort should be regulated.

scholarly journals Growth, Mortality and Exploitation Rates of African Moonfish (Selene dorsalis, Gill 1863) Encountered in the Coast of Ghana (West Africa)

2021 ◽  
Vol 2 (2) ◽  
pp. 6-10
Author(s):  
Samuel K. K. Amponsah ◽  
Berchie Asiedu ◽  
Selasi Yao Avornyo ◽  
Seyramsarah Blossom Setufe ◽  
Pierre Failler
Keyword(s):  
Mortality Rate ◽  
West Africa ◽  
Growth Parameters ◽  
Total Mortality ◽  
Mesh Size ◽  
Optimum Level ◽  
Management Measures ◽  
Simulating Annealing ◽  
Exploitation Rate ◽  
Length Frequency Data

Growth, mortality and exploitation rate of Selene dorsalis (Gill, 1863) from the continental shelf of Ghana (West Africa) were examined between July 2018 and June 2019. The study provided results on fishery dynamics parameters needed to estimate the stock status and characteristics of S. dorsalis in the coast of Ghana. Monthly length-frequency data were collected from 629 samples and analysed using fisheries models fitted in TropFishR package in R software. The von Bertalanffy growth parameters were utilised to analyse the population dynamics of the species using ELEFAN Simulating Annealing. Based on the estimates, the asymptotic total length (L∞) was 22.2 cm, the coefficient of growth (K) was 0.76 year-1, and the calculated growth performance index (phi) was 2.58 with Rn value of 0.55. The total mortality rate (Z) was 3.32 year-1 with a natural mortality rate (M) of 1.21 year-1 and fishing mortality rate (F) of 2.11 year-1. The exploitation rate (E) estimated for the species was above the optimum level of 0.5, which indicates that S. dorsalis is overexploited in the coast of Ghana. It can be concluded that the exploitation rate of S. dorsalis has exceeded the optimum limit, hence the need for enforcement and improvement of fisheries management measures such as mesh size regulations, capping of canoes, closed fishing seasons and compliance with fisheries policies.

scholarly journals POPULATION DYNAMICS OF MALAYAN LEAF FISH (Pristolepisgrooti Blkr.) IN RANAU LAKE, SOUTH SUMATRA

2018 ◽  
Vol 24 (2) ◽  
pp. 125
Author(s):  
Sevi Sawetri ◽  
Subagdja Subagdja ◽  
Dina Muthmainnah
Keyword(s):  
Mortality Rate ◽  
Growth Parameters ◽  
Total Mortality ◽  
Natural Mortality ◽  
Fishing Mortality ◽  
Frequency Data ◽  
Length Frequency ◽  
Lake Ecosystems ◽  
Exploitation Rate ◽  
Length Frequency Data

The Malayan leaf fish or locally named as kepor (Pristolepis grooti) is one of important biotic components in Ranau Lake ecosystems. This study aimed to estimate population dynamic and exploitation rate of kepor in Ranau Lake, South Sumatera. The population parameters are estimated based on length frequency data which were collected in March to October 2013. Growth parameters and fishing mortality rates were calculated using FiSAT software package. The results showed that kepor’s growth was negative allometric, which tended to gain length faster than weight. Kepor population was dominated (42%) by individual length of 10.0 to 11.0 cm. Predicted length infinity (L) was 17.28 cm with high value of growth rates (K) of 1.4 year-1. The natural mortality rate (M) is 2.57 year-1, the fishing mortality rate (F) is 5.36 year-1 and total mortality rate (Z) is 7.93 year-1. The exploitation rate of Malayan leaf fish in Ranau Lake (E = 0.68 year-1) has passed the optimum score.  

scholarly journals Quantifying relative fishing impact on fish populations based on spatio-temporal overlap of fishing effort and stock density

2013 ◽  
Vol 70 (3) ◽  
pp. 618-627 ◽  
Author(s):  
Morten Vinther ◽  
Margit Eero
Keyword(s):  
Fishing Effort ◽  
Fish Populations ◽  
Fishing Mortality ◽  
Fishing Impact ◽  
Management Measures ◽  
Stock Assessments ◽  
Spatio Temporal ◽  
Substantial Decline ◽  
The Impact ◽  
Temporal Overlap

Abstract Vinther, M., and Eero, M. 2013. Quantifying relative fishing impact on fish populations based on spatio-temporal overlap of fishing effort and stock density. – ICES Journal of Marine Science, 70: 618–627. Evaluations of the effects of management measures on fish populations are usually based on the analyses of population dynamics and estimates of fishing mortality from stock assessments. However, this approach may not be applicable in all cases, in particular for data-limited stocks, which may suffer from uncertain catch information and consequently lack reliable estimates of fishing mortality. In this study we develop an approach to obtain proxies for changes in fishing mortality based on effort information and predicted stock distribution. Cod in the Kattegat is used as an example. We use GAM analyses to predict local cod densities and combine this with spatio-temporal data of fishing effort based on VMS (Vessel Monitoring System). To quantify local fishing impact on the stock, retention probability of the gears is taken into account. The results indicate a substantial decline in the impact of the Danish demersal trawl fleet on cod in the Kattegat in recent years, due to a combination of closed areas, introduction of selective gears and changes in overall effort.

scholarly journals Age, growth and mortality of the European Seabass, (Dicentrarchus Labrax) in Bardawil lagoon, North Sinai, Egypt

2021 ◽  
pp. 042-046
Author(s):  
El-Desoki Menna O ◽  
Younis Younis M ◽  
A Youssef El-Dakar ◽  
Ahmed Salem M ◽  
Ahmed Kassem S ◽  
...  
Keyword(s):  
Growth Parameters ◽  
Age Groups ◽  
Dicentrarchus Labrax ◽  
Mortality Rates ◽  
Von Bertalanffy ◽  
Fishing Mortality ◽  
European Seabass ◽  
Exploitation Rate ◽  
The Relationship ◽  
North Sinai

Age, growth, and mortality of European Seabass (Dicentrarchus labrax) were studied from a small-scaled fishery of Bardawil lagoon, (North Sinai, Egypt). 181 specimens (16.6 to 35 cm total Length and 39.8 to 367.2 g total weight). The relationship between length and weight was W = 0.0054L3.1428. Age was determined by otoliths and age groups I to IV years were observed. Growths in length and weight at the end of each year were calculated. The growth parameters of von Bertalanffy equation were calculated as (L∞ = 48.69 cm, K = 0.1677 yr -1 and t0 = -0.447 yr -1). Growth performance index was calculated (φ = 2.60 for length and 1.25 for weight). Mortality rates were 0.867 yr-1, 0.25 yr1and 0.617 yr-1 for total, natural and fishing mortality, respectively. The currently exploitation rate E = 0.712 yr-1 indicating that, the population of this species is being heavily exploited.

scholarly journals PARAMETER POPULASI IKAN BETOK (Anabas testudineus (BLOCH, 1792)) DI EKOSISTEM PAPARAN BANJIR SUNGAI MUSI, Lubuk Lampam

2019 ◽  
Vol 18 (1) ◽  
Author(s):  
Syarifah Nurdawati ◽  
Zulkarnaen Fahmi ◽  
Freddy Supriyadi
Keyword(s):  
Growth Parameters ◽  
Total Mortality ◽  
Fish Length ◽  
Fishing Mortality ◽  
Anabas Testudineus ◽  
Weight Growth ◽  
Exploitation Rate ◽  
Management Policies ◽  
Distribution Of Fish ◽  
Musi River

Anabas testudineus Bloch, 1792 is economically important fish species found in Lubuk Lampam floodplains of Musi River. Fishing activities that take place throughout the year can affect reproduction patterns and recruitment (new additions) of fish. This study aims to evaluate several parameters of betok fish populations that can be used as input for fish resource management policies in floodplains of Musi river. A total of 3271 samples of betok fish caught by fishermen from March to November 2011 were collected to obtain data on fish length and weight. Growth parameters (L∞, K, Z dan M) were calculated using FiSAT II based on the length frequency distribution of fish. The values of L∞ and K were obtained at 204.75 mm and 0.24 / year respectively while the maximum age of fish was estimated to be 4.36 years. The total mortality (Z) and natural mortality (M) of betok fish is 0.99 / year and 0.42 / year, Fishing mortality (0.56/year). The exploitation rate (0.57) was slightly lower than the predicted value (Emax= 0.69) indicating that Anabas  testudineus was near fully exploited in the Lubuk Lampam floodplain ecosystem.  

scholarly journals Dinamika pertumbuhan sepat siam (Trichopodus pectoralis, Regan 1910) di Perairan Rawa Banjiran Patra Tani Sumatra Selatan

DEPIK ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 444-451
Author(s):  
Aroef Hukmanan Rais ◽  
Sevi Sawestri ◽  
Dina Muthmainnah
Keyword(s):  
Native Species ◽  
Condition Factor ◽  
Growth Parameters ◽  
Mesh Size ◽  
Flood Plain ◽  
The Other ◽  
Long Period ◽  
Fish Samples ◽  
Fishing Gears ◽  
Exploitation Rate

The exploitation of Sepat siam (Trichopodus pectoralis, Regan 1910) that include native species of floodplain has been done on many years. One of the main fishing areas of this commodity is Patratani floodplain, Muara Enim Regency, South Sumatra. This commodity has been exploited over a long period and is expected to have a high pressure of fishing. The aim of this paper is to compare the utilization of sepat siam resources based on growth, mortality, and exploitation parameters between 2010 and 2017. Fish samples were collected monthly started from March to December in 2010, and April to December in 2017. The sample got from local fishers who fished around Patratani flood-plain waters. Sepat siam samples were measured on length (cm) and weight (gram) every month. The analysis has concluded based on the condition factor in both years. The growth parameters were analyzed by FiSATII software. The result of FiSAT II analysis drawn the growth factor was 0.86 in 2010, and have been growing slow to be 0.55 in 2017. The length infinitive in 2010 was around 21.5 cm and decreased to 18.3 in 2017. The other results showed that the exploitation level decreased from 0.61 in 2010 to 0.53 in 2017. The exploitation rate proved that the utilization of sepat siam was decreased but sill on overfishing conditions. The length size of sepat siam related to the optimum mesh size fishing gears was decreasing in 2017 compared to 2010. The age analysis shows for 21.5 cm of the infinitive length is achieved for 7 months in 2010, while 18.3 cm of that is reached for 10,5 months in 2017.Keywords:Exploitation levelFloodplainSepat siamABSTRAKKegiatan penangkapan Sepat siam (Trichopodus pectoralis, Regan 1910) yang merupakan spesies asli ikan rawa banjiran sudah dilakukan bertahun-tahun. Salah satu lokasi penangkapan komoditas ini adalah di rawa banjiran Patratani, Kabupaten Muara Enim, Provinsi Sumatra Selatan.Komoditas ini telah mengalami eksploitasi dalam jangka waktu yang lama dan diperkirakan mengalami tekanan penangkapan yang besar.Tulisan ini bertujuan untuk menampilkan eksploitasi atau pemanfaatan ikan sepat siam berdasarkan parameter pertumbuhan, mortalitas, dan eksploitasi pada tahun 2010 dan 2017. Sampel ikan dikumpulkan setiap bulan yaitu dimulai Maret hingga Desember 2010.Kegiatan pengumpulan sampel dilanjutkan pada April hingga Desember 2017.Sampel ikan diperoleh dari tangkapan nelayan lokal yang memancing di sekitar perairan rawa banjiran Patratani.Sampel ikan diukur panjang (cm) dan berat (gram).Parameter pertumbuhan dianalisis menggunakan perangkat lunak FiSAT II. Hasil analisis FiSAT II menggambarkan faktor pertumbuhan sepat siam pada 2010 sebesar 0,86, dan tumbuh melambat menjadi 0,55 pada 2017. Panjang infinitif sepat siam pada 2010 sekitar 21,5 cm dan turun menjadi 18,3 pada 2017. Analisis tingkat eksploitasi menunjukkan hasil menurun dari 0,61 pada 2010 dan 0,53 pada 2017, namun masih dalam kondisi penangkapan ikan menunjukkan tangkapan berlebih. Hubungan antara ukuran panjang sepat siam dengan ukuran optimal alat tangkap menunjukkan hasil menurun pada 2017. Analisis usia menunjukkan bahwa panjang infinitif 21,5 cm dicapai selama 7 bulan pada 2010, sementara perlu waktu 10,5 bulan pada 2017 untuk mencapai panjang infinitif 18,3 cm.Katakunci:Tingkat eksploitasiRawa BanjiranSepat siam

scholarly journals Population dynamics and the management of the Indo-Pacific king mackerel Scomberomorus guttatus from the upper Bay of Bengal off Bangladesh coast

1970 ◽  
Vol 27 (2) ◽  
pp. 82-90 ◽  
Author(s):  
H Rashid ◽  
MG Mustafa ◽  
S Dewan
Keyword(s):  
Bay Of Bengal ◽  
Sustainable Management ◽  
Growth Parameters ◽  
Fishing Mortality ◽  
Length Frequency ◽  
Growth Constant ◽  
Recruitment Pattern ◽  
Exploitation Rate ◽  
King Mackerel ◽  
Bangladesh Coast

Growth and mortality parameters, exploitation rates, annual recruitment patterns and length-weight relationships were estimated using FiSAT program from monthly length-frequency and weight samples of Indo-Pacific king mackerel, Scomberomorus guttatus, captured mainly by drift gill nets from the upper Bay of Bengal off Bangladesh coast. The aim was to estimate growth parameters, mortality rates, exploitation rate and recruitment pattern of S. guttatus for sustainable management. The von Bertalanffy growth parameters asymptotic length L∞ (cm) and growth constant K (per year) were 73.5 and 0.6, respectively. The L∞ and Z/K estimates provided by Wetherall plot were 73.3 and 2.3 cm. The annual rate of fishing mortality (F = 0.806) was low compared to the relatively high natural mortality (M = 0.994). The exploitation rate (E = 0.45) shows that the species was not over-exploited in the region. About 77.1% of S. guttatus were recruited during May-July and 23.0% during September-October. The growth performance index (φ′) was 3.5. The total length and body weight relationship was W = 0.0101 L 2.8622 suggesting that the growth rate was negative allometric (b<3). The growth parameters derived in the current study are comparable with previous estimates available for the same species. DOI: 10.3329/bvet.v27i2.7558 Bangl. vet. 2010. Vol. 27, No. 2, 82-90

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