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  4. Investigate the effects of wind-induced microturbulence on yellowfin larval survival
Objectives
Estimate the optimal microturbulence and wind speed for the survival of yellowfin larvae and examine any association between yellowfin recruitment and historical wind speeds in the EPO
Background
  • Studies have shown that feeding success and survival of marine fish larvae can be influenced by the levels of wind-induced microturbulence in the larval feeding environment
  • Multiple experiments were conducted over 4 years to examine microturbulence effects on yellowfin larval survival, and optimal turbulence estimates for larval survival were converted to optimal wind speeds
  • Estimated optimal wind speeds for larval survival have been examined for correlations with yellowfin recruitment during 1987-2007
Relevance for management
The wind speed-recruitment analysis is promising for assessing yellowfin recruitment patterns in relation to larval survival
Duration
24 months
Workplan and status
  • June-December 2019: Refine analyses of survival and feeding data and finalize wind speed-recruitment analysis
  • January-December 2021: Complete manuscript and submit to scientific journal
External collaborators
University of Tokyo
Deliverables
  • Presentations for SAC-09, SAC-10 and SAC-11
  • Publication of results in a scientific journal
Updated date: 01 Mar 2023
Progress summary for the reporting period
  • Analysis of experimental survival and feeding data in response to microturbulence completed.
  • Feeding parameters examined in relation to microturbulence included average prey and biomass consumption and size of prey captured.
  • A meeting with Dr. Shingo Kimura at University of Tokyo in August 2019 included adjustments and improvements to the final modeling of the experimental turbulence results.
  • During 2022 the experimental analysis of larval feeding responses to microturbulence was expanded
  • A manuscript summarizing experimental estimates of optimal microturbulence and a wind speed-recruitment analysis of select areas of the EPO is nearing completion
Challenges and key lessons learnt
Measuring microturbulence in experimental tanks is difficult on a scale that is relevant to the foraging environment of larval yellowfin. This was addressed by using a microacoustic doppler velocimeter (ADV) to measure turbulent dissipation rates in the tanks at microscale (5 mm x 5 mm) precision; they were also estimated using a small-scale (m3 ) model developed by a colleague at the University of Tokyo
Presentation at SAC-10 and SAC-11
Presentation at 45th Larval Fish Conference, August 2022
Comments
This project will be completed with the submission of a manuscript by late 2023.