|Influence of environmental factors on artisanal Octopus vulgaris landings in Asturian waters (N Spain)|
Volkenandt, M. (2010). Influence of environmental factors on artisanal Octopus vulgaris landings in Asturian waters (N Spain). MSc Thesis. University of Oviedo, Department of Biology of Organisms and Systems/Erasmus Mundus Master of Science in Marine Biodiversity and Conservation (EMBC): Aviedo. 23 + annexes pp.
University of Oviedo (UNIOVI), more
|Available in|| Author |
- VLIZ: Archive VLIZ ARCHIVE A.THES2 
- VLIZ: Non-open access 230608
|Document type: Dissertation|
Abundance; Catch rate; Cephalopod fisheries; Environmental factors; Fisheries; Stocks; Surface temperature; Cephalopoda [WoRMS]; Octopus vulgaris Cuvier, 1797 [WoRMS]; ANE, Biscay Bay [Marine Regions]; ANE, Spain, Asturias [Marine Regions]; Marine
|Author|| || Top |
Cephalopods are one of the few remaining groups with a high exploitation potential on a global scale. Octopus vulgaris (Cuvier 1797) is the most fished cephalopod species in Asturian waters (Northern Spain) by artisanal fisheries. This paper investigated the status of this fishery after the installation of a management plan, which included a closed season, minimum capture weight, and a fishing gear restriction. We considered the social impact of the management plan by conducting a survey on fishermen and their fishing practices. Further, inter-annual fluctuations in catch per unit effort (CPUE) were analyzed using generalized additive models (GAM). The effect of spatial-temporal variations in water temperature, chlorophyll a (Chl a) concentration, and upwelling was tested using data from seven ports along the western Asturian coast. O. vulgaris adjusted its life cycle to the most favorable regional conditions. For semelparous species with a short lifespan, stock abundance depends on the strength of annual recruitment. The most sensitive life stage for octopus, the paralarval stage, occurred in autumn, which was determined to be the critical season in the recruitment process. The GAM revealed that higher sea surface temperature (SST) and Chl a concentrations of the previous autumn positively affect the catch rates in the following fishing season. Interestingly, this reveals a pattern of O. vulgaris with large-scale geographical differences in comparison to other studies. The fisheries in Asturias were stable for the studied period 2000- 2009, and the implemented management strategies seem to be successful. Because predictions about climate change effects on octopus abundance are difficult to make, the strong regional characteristics of octopus populations require additional research. A stronger collaboration with fishermen is suggested for consistently sustainable octopus exploitation.