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Common octopus (Octopus vulgaris) fisheries in Andalusia Mediterranean coast: Trends in fleet dynamics and the population structure of stock

2019; Frontiers Media; Volume: 6; Linguagem: Inglês

10.3389/conf.fmars.2019.08.00067

2296-7745

Cristina Ciércoles, A. Garrido, Estefanía León, J. M. de la Serna, M.J. Acosta, J.L. Pérez-Gil, Pedro Torres, María González,

Veterinary Pharmacology and Anesthesia

Event Abstract Back to Event Common octopus (Octopus vulgaris) fisheries in Andalusia Mediterranean coast: Trends in fleet dynamics and the population structure of stock Cristina Ciércoles1, 2*, Ana Garrido3, Estefanía León4, JOSE MIGUEL SERNA2, MANUEL JESUS ACOSTA2, JOSE LUIS PÉREZ-GIL2, Pedro Torres2 and María González2 1 University of Málaga, Spain 2 Oceanographic Center of Málaga, Spanish Institute of Oceanography (IEO), Spain 3 Agency of Agrarian and Fishing Management of Andalusia, Spain 4 Research Planning and Development SA, Spain In the last years cephalopods are increasing in economic importance and in consequence there have been a rise in their demand and their global landings (Hunsicker et al. 2010). In Andalusia (Mediterranean coast) Octopus vulgaris is one of the most important marketed cephalopod with a great socio-economical importance in the local fisheries being the fourth one in landings of all species (6.2% total weight of landings) and the first one in total landed value (16.63% of the total first sale value) (Official Regional statistics 2018). Common octopus is mainly fished by coastal trawlers (OTB) and artisanal fishery focused in common octopus catches with pots and traps (FPO). Also a small percentage are captured by small-scaling fleet with trammel nets, hooks and other fishing gears. Trawling fleet operates deeper than 50 m only in soft, sandy or muddy bottoms and landing a wide range of commercial species. Artisanal fishery fleet targeting O. vulgaris operates in any type of bottoms in coastal areas. These fisheries are regulated by nationally and regionally rules, nevertheless octopus is a difficult resource to manage due to their biological characteristics (short life span, rapid growth, high natural mortality and sensitivity to environmental conditions with highly recruitment success) (Pierce et al. 2010, Vargas-Yañez et al. 2009).The aim of this study is to improve the knowledge of fishery dynamics and the population of the octopus stock in order to contribute to its better management for a sustainable exploitation. Study area comprises the Mediterranean coast of the Andalusia Region. Data of fleet and landings during 2002-2017 were obtained out of the annual official fisheries statistical. In this work, fishing effort was measured in terms of number of trips with octopus landings. Total body weight, recorded to the lower 100 g, was selected as a measure of size. Biological data were obtained from at sea and at market monthly samplings of the two main fleets targeting octopus (trawlers and pots), during 2010-2017. The sampling was located along the coast, from Estepona to Almería. To standardize the individual size with others publications, dorsal mantel length (DML) was calculated applying the length-weight relationship: W=a*Lb, with a (2.0427) and b (2.4204) estimated via ordinary least-squares regression (González M. Pers. Com). A statistical analysis of the data was carried out with Excel software. Operational fleet landing O. vulgaris in the study area was composed of 189 OTB and 90 FPO vessels in 2002 and while OTB fleet decreased to 95 vessels in 2017, FPO fleet increased to 178. Regarding the fishing effort, it decreased from 10863 trips (57 trips/vessel) in 2002 to 9320 (98 trips/vessel) in 2017 for OTB and steadily increased from 1329 (15 trip/vessel) to 9647 trips (54 trip/vessel) for FPO. Total annual landings have fluctuated widely from 716 t to more than 1400 t along the time-series (2002-2017) with a maximum of ~1480 t in 2013. Overall, OTB landings decreased over time (with a maximum of ~700 t and minimum of ~220 t) while FPO landings increased significantly and were greater than OTB since 2012. The average in terms of first-sale price for landings increased in the same period from 4.5 €•Kg to more than 7 €•Kg. Octopus is fished all along the coastline although ports located in the occidental coast had the larger landings. The most representative ports in terms of total landings were Caleta de Vélez (229 ± 19 t•y-1 with a contribution of 51 % for OTB and 49% of FPO), Fuengirola (154 ± 10 t•y-1, 40% OTB and 60% FPO), Estepona (153 ± 15 t•y-1, 50% of both OTB and FPO) and Marbella (115 ± 10 t•y-1, 57 % OTB and 43 % FPO). According to the intra-annual population dynamics, O. vulgaris showed a visible seasonality in landings although it differs between gears. For OTB the highest landings were in the first quarter of the year, while the highest landings of FPO were in July. The lowest landings were in September-October for both gears. In general terms the yield, landing per unit of effort, was higher for FPO (annual average 64 ± 3 kg•trip-1) and in both gears it started to increas up to September with a maximum in late spring. The population structure of O. vulgaris display gear-related differences. Commercial size range during 2010-2017 were 12-32 cm DML for trawlers and 12-29 cm for pots, while the corresponding modal size were 13-14 cm and 13-16 cm, respectively. Pots captured larger specimens (average 16.15 ± 1.25 cm) than trawlers (average 14.84 ± 1.35 cm) (t=2.6; p=0.005). Considering the average size by month the larger individuals were catch during the summer in both cases even though for pots the largest specimens were landed in July and the size decreased until October while for OTB the largest were in September and the size decreased until November. Intra-annuals landings and population structure in both gears reveal a marked seasonality reflecting the octopus' annual life cycle described by several authors (short life span, rapid growth and high sensitivity to the recruitment to environmental conditions)(Guerra 1981, González et al. 2011, Quetglas et al. 2015). In the study area the spawning season takes place from late spring to the end of summer (Tirado et al. 2003, García-Martinez et al. 2017), which results in higher landings and higher average individuals weight specially in FPO. After, the adults die while juvenile-recruitment settle in September to November and incorporate to fisheries from late autumn to winter. The recruitment of young individuals to the fishery and their fast growth is reflected in the increase of catches of both fisheries from late winter to late spring. In conclusion, from 2002 the number of trips targeting octopus have been multiplied by 7 in FPO and they have been stabilized in OTB. However, after 2013, landings have not increased according to the effort, and the productivity of trips are reducing every year. In addition, the growing of their economic value makes octopus more valuable for fishermen what could increase the risk of overexploitation. Acknowledgements This project has been co-funded by the EU through the European Maritime and Fisheries Fund (EMFF) within the National Program of collection, management and use of data in the fisheries sector and support for scientific advice regarding the Common Fisheries Policy. We would like to thanks the crew of the fishing boats that collaboration with the biological study, provide the sampling on board. References Garcia-Martínez MC et al (2017) Short comment about the octopus life cycle in the northern Alboran Sea ( western Mediterranean Sea ). J Fish Res 1(1):34–7. González M et al (2011) Fisheries and reproductive biology of Octopus vulgaris (Mollusca: Cephalopoda) in the Gulf of Alicante (Northwestern Mediterranean). Mediterr Mar Sci 12(2):369-389. Guerra A (1981) Spatial distribution pattern of Octopus vulgaris. J Zool 195:133–146. Hunsicker M et al. (2010) The contribution of cephalopods to global marine fisheries: can we have our squid and eat them too?. Fish Fish 11: 421-438. Pierce GJ et al (2010) Cephalopod biology and fisheries in Europe. ICES Cooperative Resarch Report No. 303. Quetglas A et al (2015) Can Mediterranean cephalopod stocks be managed at MSY by 2020? The Balearic Island as a case study. Fish Manag Ecol 22: 349-358. Tirado C et al (2003) La reproducción del Pulpo (Octopus vulgaris) y el choco (Sepia officinalis) en la costa andaluza. Sevilla. Vargas-Yáñez M et al (2009) Relationships between Octopus vulgaris landings and environmental factors in the northern Alboran Sea (Southwestern Mediterranean). Fish Res 99(3):159–67. Keywords: Mediterranean, northwest, Octopus (Octopus vulgaris), Otter trawl, Artisanal fleet, Fisheries Conference: XX Iberian Symposium on Marine Biology Studies (SIEBM XX) , Braga, Portugal, 9 Sep - 12 Sep, 2019. Presentation Type: Poster Presentation Topic: Fisheries, Aquaculture and Biotechnology Citation: Ciércoles C, Garrido A, León E, SERNA J, ACOSTA M, PÉREZ-GIL J, Torres P and González M (2019). Common octopus (Octopus vulgaris) fisheries in Andalusia Mediterranean coast: Trends in fleet dynamics and the population structure of stock. Front. Mar. Sci. Conference Abstract: XX Iberian Symposium on Marine Biology Studies (SIEBM XX) . doi: 10.3389/conf.fmars.2019.08.00067 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 08 May 2019; Published Online: 27 Sep 2019. * Correspondence: PhD. Cristina Ciércoles, University of Málaga, Málaga, Spain, criscier@uma.es Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Cristina Ciércoles Ana Garrido Estefanía León JOSE MIGUEL SERNA MANUEL JESUS ACOSTA JOSE LUIS PÉREZ-GIL Pedro Torres María González Google Cristina Ciércoles Ana Garrido Estefanía León JOSE MIGUEL SERNA MANUEL JESUS ACOSTA JOSE LUIS PÉREZ-GIL Pedro Torres María González Google Scholar Cristina Ciércoles Ana Garrido Estefanía León JOSE MIGUEL SERNA MANUEL JESUS ACOSTA JOSE LUIS PÉREZ-GIL Pedro Torres María González PubMed Cristina Ciércoles Ana Garrido Estefanía León JOSE MIGUEL SERNA MANUEL JESUS ACOSTA JOSE LUIS PÉREZ-GIL Pedro Torres María González Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.