MARAM_Tristan_2022_MAR_ 02 (biomass survey index update).pdf (1.21 MB)
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Tristan Group Biomass Survey results including data from the 2021 season

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posted on 09.05.2022, 11:48 by Susan HollowaySusan Holloway

This paper reports the updated biomass indices (to include the 20211 season) obtained from the annual biomass survey at each island. The decline since the 2018 season at the outer islands of Inaccessible, Nightingale and Gough has been reversed with increases shown at all three islands by these most recent results. The Tristan biomass index value has also improved. There have been some changes over time in the size distributions, the most marked of which have been recent steady increases at Inaccessible and Tristan in the mean length of the survey catch, but these have now reversed for the 2021 data collected. The recent decline in the mean length of the catch from Gough has also changed direction. The percentage of females in the catch at Gough (around 25-35%) is much higher that at the other three islands (around 5-15%). The percent females at both Tristan and Inaccessible are the highest since the start of the surveys in 2006.

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Department of Mathematics and Applied Mathematics, University of Cape Town