scholarly journals Mortality rate of silky sharks (Carcharhinus falciformis) caught in the tropical tuna purse seine fishery in the Indian Ocean

2014 ◽  
Vol 71 (6) ◽  
pp. 795-798 ◽  
Author(s):  
François Poisson ◽  
John David Filmalter ◽  
Anne-Lise Vernet ◽  
Laurent Dagorn
Keyword(s):  
Mortality Rate ◽  
Indian Ocean ◽  
Purse Seine ◽  
The Indian Ocean ◽  
Carcharhinus Falciformis ◽  
Handling Practices ◽  
Tropical Tuna ◽  
Harsh Conditions ◽  
Purse Seine Fishery ◽  
Overall Mortality

Scientists aboard French purse seine vessels recorded the number and condition of silky sharks (Carcharhinus falciformis) caught during three fishing cruises in the Indian Ocean. A sample of 31 individuals that showed signs of life were tagged with satellite tags to investigate their postrelease mortality. The majority of individuals (95%) were brought on board using the brailer. Combining the proportion of sharks that were dead (72%) and the mortality rate of those released (48%), the overall mortality rate of brailed individuals was 85%. Few individuals (5%) were not brailed as they were entangled and landed during the hauling process. The survival rate of these individuals was high, with an overall mortality rate of meshed individuals of 18%. The combination of these two categories led to an overall mortality rate of 81%. This high value reflects the harsh conditions encountered by sharks during the purse seine fishing process. Consequently, methods that prevent sharks being brought on board are a priority for future investigations, but good handling practices should also be promoted as they could reduce mortality by at least 19%.

Monitoring of Spanish flagged purse seine fishery targeting tropical tuna in the Indian ocean: Timeline and history

Marine Policy ◽  
2020 ◽  
Vol 119 ◽  
pp. 104094
Author(s):  
José Carlos Báez ◽  
María Lourdes Ramos ◽  
Miguel Herrera ◽  
Hilario Murua ◽  
José Luis Cort ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Purse Seine ◽  
The Indian Ocean ◽  
Tropical Tuna ◽  
Purse Seine Fishery

scholarly journals Precision in bycatch estimates: the case of tuna purse-seine fisheries in the Indian Ocean

2012 ◽  
Vol 69 (8) ◽  
pp. 1501-1510 ◽  
Author(s):  
Monin J. Amandè ◽  
Emmanuel Chassot ◽  
Pierre Chavance ◽  
Hilario Murua ◽  
Alicia Delgado de Molina ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Linear Models ◽  
Purse Seine ◽  
Reliable Estimate ◽  
Routine Practice ◽  
Marine Animals ◽  
Trade Offs ◽  
The Indian Ocean ◽  
Current Sampling ◽  
Tropical Tuna

Abstract Amandè, M. J., Chassot, E., Chavance, P., Murua, H., Delgado de Molina, A., and Bez, N. 2012. Precision in bycatch estimates: the case of tuna purse-seine fisheries in the Indian Ocean. – ICES Journal of Marine Science, 69: . Estimating bycatch, i.e. the incidental catch of non-target marine animals and undersized individuals of target species, by raising observer data to the whole fishery is routine practice. The annual bycatch of the European tropical tuna purse-seine fishery over the period 2003–2009 was estimated at 11 590 t [95% confidence interval: (8165–15 818 t)], corresponding to 4.7% of the tuna landings. An analysis of the variability in the precision of this estimate, based on generalized linear models and Monte Carlo simulations, showed that the current sampling coverage of the tropical tuna fishery observer programme, which is 4.6% of the fishing trips, resulted in large uncertainties in bycatch estimates by species, i.e. none of the estimates have a relative root mean square error smaller than 50%. Although the overall magnitude of bycatch of the fishery appeared to be small, the current sampling coverage was insufficient to give any reliable estimate for low-occurring species, such as marine turtles, some oceanic pelagic sharks, and some billfishes. Increasing the sampling coverage would likely improve bycatch estimates. Simulation outputs were produced to help define (i) trade-offs between the priority species to be monitored, (ii) the estimation precision, (iii) expected accuracy, and (iv) the associated sampling costs.

Size-selective catch in tropical tuna purse seine fishery in the Eastern Indian Ocean: Assessment on new selectivity model for purse seine net

2016 ◽  
Vol 82 (3) ◽  
pp. 391-404 ◽  
Author(s):  
Watcharapong Chumchuen ◽  
Tatsuro Matsuoka ◽  
Kazuhiko Anraku ◽  
Sukchai Arnupapboon
Keyword(s):  
Indian Ocean ◽  
Purse Seine ◽  
Eastern Indian Ocean ◽  
Selectivity Model ◽  
Tropical Tuna ◽  
Purse Seine Fishery

scholarly journals PARAMETER POPULASI HIU KEJEN (Carcharhinus falciformis) DI PERAIRAN SELATAN NUSA TENGGARA BARAT

2018 ◽  
Vol 9 (3) ◽  
pp. 175
Author(s):  
Umi Chodrijah ◽  
Irwan Jatmiko ◽  
Agus Arifin Sentosa
Keyword(s):  
Mortality Rate ◽  
Indian Ocean ◽  
Total Mortality ◽  
Survey Method ◽  
Growth Equation ◽  
Von Bertalanffy ◽  
Fish Samples ◽  
Silky Shark ◽  
The Indian Ocean ◽  
Carcharhinus Falciformis

Hiu kejen atau silky shark (Carcharhinus falciformis) merupakan salah satu spesies hiu dari famili Carcharhinidae yang banyak tertangkap di Samudera Hindia Selatan Jawa. Berdasarkan keputusan sidang CoP-17 di Johannesburg species ini masuk dalam daftar merah Apendik II CITES, sejak saat itu pengelolaan hiu kejen menjadi perhatian khusus pada perikanan tangkap. Tujuan penelitian ini adalah untuk mendapatkan informasi parameter populasi ikan hiu kejen di perairan Samudera Hindia bagian Selatan Nusa Tenggara. Penelitian dilakukan di Tempat Pendaratan Ikan Tanjungluar, Lombok Timur tahun 2016. Pengukuran contoh hiu meliputi panjang total tubuh, nisbah kelamin serta panjang klasper. Hasil penelitian terhadap 3002 ekor ikan contoh menunjukkan bahwa kisaran panjang total hiu kejen (Carcharhinus falciformis) antara 65-300 cm (betina) dan 74-315 cm (jantan). Rerata ukuran panjang total adalah 187,66 cm (betina) dan 195 cm (jantan). Parameter pertumbuhan menurut Von Bertalanffy, meliputi laju pertumbuhan (K), panjang asimptotik (L) dan umur ikan pada saat panjang ke-0 (t0), masing-masing sebesar 0,42/tahun; 331,28 cmTL dan -0,20/ tahun. Persamaan kurva pertumbuhan von Bertalanffy untuk hiu kejen yaitu Lt = 331,28[1–e–0.,42(t+0.20)]. Parameter mortalitas hiu kejen meliputi laju kematian total (Z), laju kematian alamiah (M) dan laju kematian karena penangkapan (F) masing-masing sebesar 2,79/tahun; 0,49/tahun dan 2,30/tahun. Laju eksploitasi (E) hiu kejen sebesar 0,82 menandakan eksploitasi terhadap spesies ini cenderung sudah tinggi.Silky shark (Carcharhinus falciformis) is one of the family Carcharhinidae that commonly caught in the Indian Ocean South of Java. The purpose of this study was to obtain information on the populations parameters of silky shark caught in the waters of Indian Ocean Southern part of Nusa Tenggara. The study was conducted at fish landing sites in Tanjungluar, East Lombok from January to December 2016. The method used in this research was survey method. Observations included total body length, sex ratio and clasper length measured with direct measurements and visual observations in the field. From a total 3002 fish samples showed that the total length range for silky shark (Carcharhinus falciformis) caught in the waters of the Indian Ocean landed in Tanjungluar were between 65-300 cm TL (female) and 74-315 cmTL (male), with the average length of 187, 66 cmTL (female) and 195 cm TL (male). The estimated Von Bertalanffy growth parameters of length infinity (L), growth rate (K) and theoretical age of fish at zero length (t0) were 331.28 cmTL, 0.42 / year and -0.20 years, respectively. The Von Bertalanffy growth equation for silky shark was Lt = 331.28 [1-e-0.42(t+0.20)]. The calculated Parameters for silky shark mortality including total mortality rate (Z), the natural mortality rate (M) and the fishing mortality rate (F) were 2.79 / year, 0:49 / year and 2.30 / year, respectively. The exploitation rate (E) of silky shark of 0.82 indicates the exploitation of this species has already high.

scholarly journals The Biological Aspect of Mackerel Scad (Decapterus Macarellus Cuvier, 1833) In Samudera Hindia (West Sumatera Block)

Omni-Akuatika ◽  
2020 ◽  
Vol 16 (3) ◽  
pp. 92
Author(s):  
Heri Widiyastuti ◽  
Andina Ramadhani Putri Pane ◽  
Moh Fauzi ◽  
Thomas Hidayat
Keyword(s):  
Indian Ocean ◽  
Sex Ratio ◽  
Average Length ◽  
Mesh Size ◽  
Growth Patterns ◽  
Purse Seine ◽  
West Sumatra ◽  
The Indian Ocean ◽  
Biological Aspects ◽  
First Maturity

Mackerel scad (Decapterus macarellus) is one of the important economical caught in the Indian Ocean West Sumatra waters captured using purse seine. Increased production of mackerel scad will lead to increased exploitation, causing population changes. Therefore, research was carried out to find out the biological aspects of the fish so that resource management can be done. The sampling was conducted in Lampulo, Sibolga, and Air Bangis from February to November 2016 with total samples of 716 fishes. This research was conduct to study some biological aspects which consist of size distribution, length-weight relationship, sex ratio, gonad maturity level, the length at first capture, and length of the first maturity in Indian ocean west Sumatera waters. The results showed that the size of the mackerel scad had ranged between 16 - 33.6 cm FL and the average was 24.5 cm. Growth patterns are allometric negative, sex ratio male and female in an unbalanced condition. The mackerel scad is most caught by purse seine in maturity condition. The average length at first captured was 25.08 cm FL and length at first mature was 20.47 cm FL. These were an ideal biological condition and must be maintained because it provides an opportunity for fish to increase the population. The mesh size purse must follow the Ministry of Maritime Affairs and Fisheries Regulation Number 71/2016 that adjusted for minimum at 1 inch. Keywords: Mackerel scad, Indian Ocean, purse seine

Sign in / Sign up

Export Citation Format

Share Document