Estimation of the spawning stock and recruitment relationship of Octopus vulgaris in Asturias (Bay of Biscay) with generalized depletion models: implications for the applicability of MSY

Rubén H. Roa-Ureta, M del Pino Fernández-Rueda, José Luis Acuña, Antonella Rivera, Ricardo González-Gil, Lucía García-Flórez

Research output: Contribution to journalArticlepeer-review

Abstract

We developed a new type of generalized depletion model adapted to the rapid life cycle of Octopus vulgaris and the data collection framework put in place in its co-managed small-scale fishery (SSF) in Asturias, northwest Spain. The model uses weekly data from 19 seasons to estimate annual recruitment and female spawners emigration out of the vulnerable stock to attend to their broods. The matched annual spawners-recruitment (SR) magnitudes are then used as observations in a non-Bayesian hierarchical inference framework. The Shepherd SR model was selected among three alternatives. The stock has a high degree of density-dependence, leading to overcompensation. The estimated SR model has an unstable equilibrium point, driving the stock to deterministic cyclic fluctuations under small disturbances. Under those conditions the maximum sustainable yield (MSY) is not applicable, lending further credence to Sidney Holt’s opposition to the MSY as a basis for the elaboration of fishery management objectives, with potentially wide relevance to the management of SSF and cephalopod fisheries. We argue that harvest rates based on mean latent productivity, a concept that includes the MSY as a special case, are more adequate and sustainable for fluctuating stocks.
Original languageEnglish
Number of pages34
JournalICES Journal of Marine Science
Early online date15 Jun 2021
DOIs
Publication statusE-pub ahead of print - 15 Jun 2021
Externally publishedYes

Keywords

  • stock recruitment
  • cephalopod fisheries
  • small scale fisheries
  • hierarchical models
  • Asturias

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