title: Accuracy of the Kirchhoff-approximation and Kirchhoff-ray-mode fish swimbladder acoustic scattering models.
abstract: The acoustic backscatter from pressure release prolate spheroids and a three-dimensional representation of a fish swimbladder (Chilean jack mackerel, Trachurus symmetricus murphyi) was calculated using four target strength models (Kirchhoff-approximation, Kirchhoff-ray-mode, finite element solution of the Helmholtz equation, and prolate-spheroid-modal-series). Smoothly varying errors were found in the Kirchhoff-approximation and Kirchhoff-ray-mode model results when compared to the other models, and provide objective criteria for constraining the use of the KA and KRM models. A generic correction technique is also proposed for the prolate spheroid estimates and tentatively tested on a jack mackerel swimbladder, resulting in improvements to the target strength estimates from the Kirchhoff-approximation and Kirchhoff-ray-mode models.
authors.affiliation: Observation Methodology, Institute of Marine Research, Bergen, Norway. gavin.macaulay@imr.no
authors.forename: Gavin J
authors.initials: GJ
authors.lastname: Macaulay
authors.forename: Héctor
authors.initials: H
authors.lastname: Peña
authors.forename: Sascha M M
authors.initials: SM
authors.lastname: Fässler
authors.forename: Geir
authors.initials: G
authors.lastname: Pedersen
authors.forename: Egil
authors.initials: E
authors.lastname: Ona
mesh_terms: D000162:Acoustics; D000400:Air Sacs; D000818:Animals; D020342:Finite Element Analysis; D008962:Models, Theoretical; D010473:Perciformes / Q000033:anatomy & histology*; D011312:Pressure