February 1st to 5th 2016
Olhão, Portugal
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Relationship between the Octopus vulgaris life cycle and its exploitation patterns by the trap fishery in the southern coast of Portugal

Oral Presentation
Natural Resources
Wednesday, February 3, 2016 -
15:15 to 15:30

Sonderblohm, C.P. 1 Pereira, J. 2 Lourenço, S. 3 Erzini, K. 4

1Centre of Marine Sciences (CCMAR), University of Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
2Instituto Português do Mar e da Atmosfera (IPMA), Departamento do Mar e Recursos Marinhos, Lisboa, Portugal
3Instituto Português do Mar e da Atmosfera (IPMA), Departamento do Mar e Recursos Marinhos, Lisboa, Portugal
4Centre of Marine Sciences (CCMAR), University of Algarve, Campus de Gambelas, 8005-139 Faro, Portugal

Fishers of the Octopus vulgaris trap fishery from the south coast of Portugal have proposed a seasonal closure of the fishery in order to protect its reproduction and recruitment. In order to implement this management strategy, information based on the scientific knowledge for defining the length and timing of such closure has been requested. For this purpose official landing data from the last 25 years (1990 – 2014) of the commercial trap fishery of O. vulgaris along the southern coast of continental Portugal have been analysed to delve into the life cycle of this cephalopod. A seasonal pattern of landings has been observed: average landings during the seasons of autumn and winter have been higher than those during the rest of the year indicating the existence of two main fishing recruitment periods. Lower landings during summer may be related to mating and spawning. The landing data is coherent with the reproductive biology described for the area, confirming an annual cycle with two main spawning periods, in spring and late summer. Non-Metric Multi-Dimensional Scaling (NMDS) applied to 12 monthly time series of landings per port exhibited a clustering pattern among them. Leeward ports had larger landings during autumn, especially in November, according to a common pattern described for the Mediterranean Sea and Gulf of Cadiz waters while windward ports had larger landings during spring, suggesting that this area to be more like the western Iberia Atlantic coast. Understanding the life cycle of O. vulgaris and its exploitation patterns by means of analysing landing data may contribute to support the management of its fishery in the Algarve.
keywords: 
Octopus vulgaris, fishery, reproductive cycle, recruitment, fishery management, Algarve

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