scholarly journals THE ASSESSMENT OF PELAGIC FISH STOCK AND ITS DISTRIBUTIONS IN INDIAN OCEAN BY SPLIT BEAM ACOUSTIC SYSTEM

2010 ◽  
Vol 2 (-) ◽  
Author(s):  
I NYOMAN ARNAYA
Keyword(s):  
Indian Ocean ◽  
Stock Assessment ◽  
Pelagic Fish ◽  
Target Strength ◽  
Fiscal Year ◽  
Fish Stock ◽  
Acoustic System ◽  
Absolute Density ◽  
Total Fish ◽  
Fish Stock Assessment

The assessment of pelagic fish stock and its distribution in Indian Ocean, especially southern part of Java-Bali-Lombok, was conducted by SIMRAD EK-500 Split-beam Acoustic System, in October-November 2001. The research was carried out by R/V Baruna Jaya VII of Indonesia Institute of Science (LIPI), under the Fish Stock Assessment Project in Indonesian Waters of fiscal year 2001. As a result, it can be reported that (I) the dominant species of pelagic fish distributed in this area is small pelagic fish with target strength (TS) values between -54.00 dB to - 37.60 dB, absolute density of between 0.07 to 218 fish/1000 m\ and total fish stock of 526.570 ton/year; (2) the large pelagic fish (some species of tuna) also distributed in the area with average TS of -27 dB, absolute density between 0.00 to 0.07 fish/100 m\ and total fish stock of 386,260 ton/year. This result still needs more accurate verification, especially on the species composition and individual size of fish by a more appropriate biological sampling method (mid-water trawl). Consequently, more acoustical surveys combined with oceanographic sampling and exploratory fishing are needed to evaluate the existing condition of marine fish resources in the area, in order to optimize and set up the relevant and accurate fisheries management plan for suitable and responsible utilization offish resources. Keywords: Split-beam Acoustic System, Fish Stock Assessment, Target Strength, Density, Distribution, Indian Ocean (southern part of Java-Bali-Lombok).

scholarly journals Fish Stock Assessment for Data-Poor Fisheries, with a Case Study of Tropical Hilsa Shad (Tenualosa ilisha) in the Water of Bangladesh

2021 ◽  
Vol 13 (7) ◽  
pp. 3604
Author(s):  
Mohammed Shahidul Alam ◽  
Qun Liu ◽  
Md. Rashed-Un- Nabi ◽  
Md. Abdullah Al-Mamun
Keyword(s):  
Stock Assessment ◽  
Mesh Size ◽  
Single Species ◽  
Assessment Method ◽  
Reference Points ◽  
Fish Stock ◽  
Total Fish ◽  
Future Potential ◽  
Fish Stock Assessment ◽  
Over Exploitation

The anadromous tropical Hilsa shad formed the largest single-species fishery in Bangladesh, making the highest contribution to the country’s total fish production (14%) and nearly 83% of the global Hilsa catch in 2018. However, increased fishing pressure made the fishery vulnerable, and hence, information on the stock condition and its response to the current degree of removal is essential to explore the future potential for sustainable exploitation. This study carried out a rigorous assessment based on three different methodological approaches (traditional length-frequency based stock assessment method for fishing mortality and exploitation, Froese’s length-based indicators for fishing sustainability, and a surplus production-based Monte Carlo method-CMSY, for fisheries reference points estimation) for the best possible estimates of the Hilsa stock status in the water of Bangladesh. The present findings revealed that the stock is likely to be overfished due to over-exploitation. Depending on the outputs, this study recommended a lower length limit for the catch (> 33 cm), distinguished a selectivity pattern (mesh size limit ≥ 8 cm), and proposed a yearly landing limit (within the range of 263,000–315,000 tons) for the sustainable management of the Hilsa fishery in Bangladesh.

Fish stock assessment a manual of basic methods

Marine Policy ◽  
1984 ◽  
Vol 8 (1) ◽  
pp. 68-69
Author(s):  
Stephen J. Lockwood
Keyword(s):  
Stock Assessment ◽  
Fish Stock ◽  
Fish Stock Assessment

scholarly journals Accuracy of Acoustic Methods in Fish Stock Assessment Surveys

Sonar Systems ◽  
10.5772/18631 ◽  
2011 ◽  
Author(s):  
S. Georgakarakos ◽  
V. Trygonis ◽  
J. Haralabous
Keyword(s):  
Stock Assessment ◽  
Fish Stock ◽  
Acoustic Methods ◽  
Fish Stock Assessment

Analysis of Threshold-Induced Bias Inherent in Acoustic Scattering Cross-Section Estimates of Individual Fish

1975 ◽  
Vol 32 (12) ◽  
pp. 2547-2551 ◽  
Author(s):  
R. T. Weimer ◽  
J. E. Ehrenberg
Keyword(s):  
Cross Section ◽  
Stock Assessment ◽  
Acoustic Scattering ◽  
Operating Conditions ◽  
Scattering Cross Section ◽  
Fish Stock ◽  
Small Fish ◽  
Scattering Cross ◽  
Electronic Circuitry ◽  
Fish Stock Assessment

During acoustic fish stock assessment surveys, it is often desirable to measure the distribution of the acoustic scattering cross-section of single fish. One of the problems in such measurements is that a threshold in the electronic circuitry discriminates against small fish. This effect is analyzed in detail, and an expression is derived for the threshold-induced bias in the mean scattering cross-section estimate. Results are plotted for a typical set of operating conditions.

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