Boarfish (Capros aper) target strength modelled from magnetis resonance imaging (MRI) scans of tis swimbladder

S.M.M. Fassler, C. O'Donnell, J.M. Jech

Research output: Contribution to journalArticleAcademicpeer-review

9 Citations (Scopus)

Abstract

Boarfish (Capros aper) abundance has increased dramatically in the Northeast Atlantic from the early 1970s after successive years of good recruitment attributed to an increase in sea surface temperature. Due to increased commercial fishing over recent years, an acoustic boarfish survey funded by the Killybegs Fishermen's Organisation was initiated by the Marine Institute to establish a baseline for the future management of this stock. In the absence of any species-specific boarfish target strength (TS), acoustic backscatter was estimated by a Kirchhoff-ray mode model using reconstructed three-dimensional swimbladder shapes which were computed from magnetic resonance imaging scans of whole fish. The model predicted TS as a function of size, fish tilt angle, and operating frequency. Standardized directivity patterns revealed the increasing importance of changes in the inclination of the dorsal swimbladder surface at higher frequencies (120 and 200 kHz) and a less directive response at lower frequencies (18 and 38 kHz). The model predicted a TS-to-total fish length relationship of TS = 20 log10(L) - 66.2. The intercept is ~1 dB higher than in the general physoclist relationship, potentially reflecting the bulky nature of the boarfish swimbladder with its relatively large circumference.
Original languageEnglish
Pages (from-to)1451-1459
JournalICES Journal of Marine Science
Volume70
Issue number7
DOIs
Publication statusPublished - 2013

Keywords

  • relative frequency-response
  • pout trisopterus-esmarkii
  • herring clupea-harengus
  • cod gadus-morhua
  • species identification
  • atlantic mackerel
  • in-situ
  • kirchhoff-approximation
  • fisheries acoustics
  • walleye pollock

Fingerprint Dive into the research topics of 'Boarfish (Capros aper) target strength modelled from magnetis resonance imaging (MRI) scans of tis swimbladder'. Together they form a unique fingerprint.

Cite this