Target Strength Measurement of Myctophid (Benthosema pterotum) in the Oman Sea

Through a series of research cruises conducted by the R/V Ferdows-1 to assess Myctophid resources, using a SIMRAD EK500 scientific echosounder carried out the Target Strength measurement of Benthosema pterotum in the Oman Sea. The principal method was based on a direct in-situ split-beam measurement technique, which is implemented in the EK500 system. For real-time observations ,the target strengths corresponding to resolved single-fish echoes were collected in a histogram. Associated statistics included the number of observations and the depth range. The processing of the TS-telegram data took place in the Procomm software (version 1.16), which converted into a tabular form and based on one-coefficient regression analysis to express the TS. The second method that also yielded information on target strength of myctophid through estimation of the mean, effective backscattering cross-section of the target fish related to the method of integrating the fish layer in the front of the trawl mouth during towing and related it to the total catch observed.The final results showed the approximate equation: TS=20logL-71.7 (dB), where L is the total length of the fish in cm. The collected data can be applied to improve later biomass-backscattering cross section analysis.