Cristin-resultat-ID: 2082135
Sist endret: 31. januar 2024, 11:01
Resultat
Mastergradsoppgave
2022

The application of CW and FM sonar technology to detect a decrease in air in the swim bladder of Atlantic salmon, measurements and modeling. Master thesis

Bidragsytere:
  • Maren F. Rong

Utgiver/serie

Utgiver

Universitetet i Bergen

Om resultatet

Mastergradsoppgave
Publiseringsår: 2022
Antall sider: 130

Beskrivelse Beskrivelse

Tittel

The application of CW and FM sonar technology to detect a decrease in air in the swim bladder of Atlantic salmon, measurements and modeling. Master thesis

Sammendrag

Salmon lice and poor surface conditions are challenging for salmon aquaculture. A new innovative preventative solution is to submerge the cages below the sea surface to avoid the surface-dwelling infestation of lice larvae. However, the physostomous salmon require daily surface access, or the swim bladder will deflate. The ensues negative buoyancy leads to increased swimming speed, and over a prolonged time (2-3 weeks), the appetite and growth rate may be reduced, resulting in poor welfare. For 28 days, 500 salmon were placed in a cage submerged to 1 m depth, preventing the salmon from reaching the sea surface and refilling the swim bladder. Beneath the cage, three EK80 scientific wide-band echo sounders with 70, 120, and 200 kHz split-beam transducers were deployed to study the acoustic backscatter over time. From the backscattered signals, parameters such as the target strength (TS), volume backscattering strength (SV ), the frequency response of both TS and SV , and the swimming speed could be calculated. These parameters are studied to determine the first to indicate an insufficient air level based on signal type and frequency. The results show an increase in swimming speed and a decrease in both TS and SV values. From the measured daily T S values from both FM and CW signals, the decrease appeared to begin from day 6 of submergence. As the air in the bladder diminished, the ratio between the values from the three echo sounders increased, which was evident from TS and SV measurements, and the frequency responses. The swimming speed acquired from the acoustical recordings decreased from day 5, but the speeds were unexpectedly high. These findings may be used to develop automatic alarms that detect low swim bladder inflations or poor welfare and provide new fundamental knowledge about backscattering from salmon.

Bidragsytere

Maren F. Rong

  • Tilknyttet:
    Forfatter
    ved Universitetet i Bergen

Per Lunde

  • Tilknyttet:
    Veileder
    ved Institutt for fysikk og teknologi ved Universitetet i Bergen

Tonje Nesse Forland

  • Tilknyttet:
    Veileder
    ved Økosystemakustikk ved Havforskningsinstituttet

Frode Oppedal

  • Tilknyttet:
    Veileder
    ved Dyrevelferd ved Havforskningsinstituttet

Geir Pedersen

  • Tilknyttet:
    Veileder
    ved Økosystemakustikk ved Havforskningsinstituttet
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