In-situ measurements of the individual acoustic backscatter of European anchovy (Engraulis encrasicolus) and sardine (Sardina Pilchardus), with concurrent optical identification.

摘要: The lack of specific Target Strength (TS) values for European anchovy (Engraulis encrasicolus) and sardine (Sardina Pilchardus) in the literature has been pointed out by Working Group on Acoustic Egg Surveys Sardine Anchovy ICES Areas VIII IX. need small pelagics TS measurements conducted controlled environments was recognized group, to further investigate adequacy length equation used derive fish stock estimates clupeids waters. is a stochastic variable which largely varies wild, response changes physical (tilt angle, depth) or biological (physiology) single attributes. first requirement make sound measurement accurately identify species comprising targets. Fish target identification usually carried fishing. comparison between fishing acoustic data may be biased large differences sampling volume selectivity devices. Optical systems can improve identification, providing images simultaneously insonified echosounder. We Ifremer’s towed body ‘EROC’, fitted with an optical-acoustic system, conduct in-situ Biscay sardine, concurrent optical identification. Its combination “open” pelagic trawl termed “ENROL” allowed recording TS, while controlling prominent factors known influence distribution: species, tilt angle. Repeating EROC/ENROL-based monospecific schools should then allow definition accurate TS~length equations near horizontal species.