PT  - JOURNAL ARTICLE
AU  - Yasutoki Shibata
AU  - Jiro Nagao
AU  - Yoji Narimatsu
AU  - Eisuke Morikawa
AU  - Yuto Suzuki
AU  - Shun Tokioka
AU  - Manabu Yamada
AU  - Shigeho Kakehi
AU  - Hiroshi Okamura
TI  - Estimating maximum sustainable yield of snow crab (<em>Chionoecetes opilio</em>) off Tohoku Japan via a state-space assessment model with time-varying natural mortality
AID  - 10.1101/2020.02.02.931428
DP  - 2020 Jan 01
TA  - bioRxiv
PG  - 2020.02.02.931428
4099  - http://biorxiv.org/content/early/2020/02/03/2020.02.02.931428.short
4100  - http://biorxiv.org/content/early/2020/02/03/2020.02.02.931428.full
AB  - Yield from fisheries is a tangible benefit of ecosystem services and sustaining or restoring a fish stock level to achieve a maximum sustainable yield (MSY). Snow crab (Chionoecetes opilio) off Tohoku has been managed by a total allowable catch since 1996, although their abundance has not increased even after 2011, when fishing pressure rapidly decreased because of the Great East Japan Earthquake. This implies that their biological characteristics, such as recruits, natural mortality coefficient (M), and terminal molting probabilities (p), might have changed. We developed “just another state-space stock assessment model (JASAM)” to estimate the MSY of the snow crab off Tohoku, Japan, considering interannual variations in M and p. The multi-model inference revealed that M increased from 0.2 in 1997 to 0.59 in 2018, although it was not different among the instars, sex, nor terminal molt of crabs. The parameter p also increased by 1.34–2.46 times depending on the instar growth stages from 1997 to 2018. We estimated the MSYs in three scenarios, which drastically changed if M and p were set as they were in the past or at the current values estimated from this study. This result indicated that the MSY of snow crab would also be time-varying based on their time-varying biological characteristics.