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Project G.2.a - Develop comparative models of pre-recruit survival and reproductive patterns of Pacific tunas

01 Jun 2018 - 31 Dec 2023

Program(s) in charge: Early-life History Group
Investigate important comparative aspects of the reproductive biology, genetics and early life histories of yellowfin and Pacific bluefin tuna
  • Pre-recruit life stages of tunas are potentially key to understanding variations in abundance and reproductive patterns of tuna populations
  • Ongoing since 2011, this project has investigated the comparative growth, nutrition and survival of larval yellowfin and Pacific bluefin tuna
  • Experimental results are being used to comparatively model mortality processes occurring during the pre-recruit life stages of both species
Relevance for management
Comparative models of pre-recruit mortality processes are promising for assessing recruitment patterns of both species
30 months
Workplan and status
  • June 2018-June 2020: Complete experimental studies of comparative larval growth and finalize data analyses
  • June-December 2023: Complete manuscript and submit to scientific journal
External collaborators
Kindai University, Fisheries Laboratory;
University of Texas
  • 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
  • Comparative experimental studies of pre-recruit life stages of yellowfin and Pacific bluefin continued during 2018 and 2019. Experimental investigations of the growth and feeding patterns of Pacific bluefin larvae were carried out at the Aquaculture Institute of Kindai University in July 2018 and July 2019. Further studies were delayed in 2020-2021 due to travel restrictions of COVID-19, but experiments will be continued during 2022.
  • A comparative analysis of the larval traits (survival, growth, starvation rates) of yellowfin and Pacific bluefin is being developed to gain insights into differences in spawning patterns and nursery habitats of the two species in the Pacific Ocean.
  • Experimental results are being incorporated into models of the pre-recruit mortality processes for both species.
  • A new study was initiated in mid-2019 in collaboration with Dr. Lee Fuiman of the University of Texas to investigate the relationship between diet and daily ration of captive spawning yellowfin and the fatty acid composition of their eggs. Sampling was completed in mid-2022 and samples are being analyzed at University of Texas.
Challenges and key lessons learnt
  • SAC-09 (May 2018), SAC-10 (May 2019), SAC-11 (May 2020) and SAC-12 (May 2021)
  • 69th Tuna Conference (May 2018) and 70th Tuna Conference (May 2019)
  • 42nd Larval Fish Conference (June 2018) and 43rd Larval Fish Conference (May 2019).
  • World Aquaculture Conference (February 2020)
SAC-12-15 Review of research at the Achotines Laboratory
Two publications on this topic are being developed, and a third study was published:
Tanaka, Tenji, Tomoki Honryo, Yoshifumi Sawada, Daniel Margulies, Vernon Scholey, Jeanne Wexler, Maria Stein, Amal Biswas, and Kenji Takii. 2022. Biochemical changes occurring in yellowfin tuna eggs during embryonic development. Fishes Vol. 7, 62.
Regular program funds are supporting the ongoing studies with Kindai University and the fatty acid study of yellowfin eggs conducted in collaboration with University of Texas. Experimental sampling in 2020-2021 was delayed due to travel restrictions related to COVID-19, but experimental work was re-initiated in 2022 and is planned for mid-2023.