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- Diel variation in the catchability of rose shrimp, Parapenaeus longirostris, and associated species from a bottom trawl survey off the portuguese south coastPublication . Sonderblohm, Carlos; Fonseca, Paulo; Erzini, KarimAn experimental crustacean bottom trawling survey targeting the deep-water rose shrimp Parapenaeus longirostris was carried out off the south of Portugal over five 24-hour cycles. Although circadian bias in the catch rates for this fishery has been reported, no conclusive study had been carried out until now. Catch per unit effort oscillated with the time of the day. Total catches, both in numbers and weight considerably higher in daytime than at night, suggesting that the 24-hour light cycle strongly influences catchability of rose shrimp. The rose shrimp, shows a clear shift in abundance from daytime to night hours, with catches decreasing sharply at dusk and, then increasing significantly at dawn. Overall, the most captured fish species: european hake, Merluccius merluccius; monkfish, Lophius budegassa; european conger, Conger conger; and great forkbeard, Phycis blennoides; present the same trend, although less marked. The exceptions are: silver scabbardfish, Lepidopus caudatus; blue Whiting, Micromesistius poutassou; tongue sole, Symphurus nigrescens; atlantic mackarel Scomber scombrus and silver cod, Gadiculus argenteus; whose catches were higher in the night hours. Understanding, the circadian variability in catches of highly valuable commercial species such as the deep-water rose shrimp may contribute to an improved management, by allowing a better control of fishing effort and more efficient use of technical measures
- Do fisher associations really represent their members’ needs and opinions? The case study of the octopus fishery in the Algarve (south Portugal)Publication . Rangel, Mafalda; Pita, Cristina; de Oliveira, Manuela Maria; Guimarães, Maria Helena; Rainha, Rita; Sonderblohm, Carlos; Monteiro, Pedro; Oliveira, Frederico; Ballesteros, Marta; Gonçalves, Jorge Manuel Santos; Pierce, Graham J.; Erzini, KarimFishers’ participation in the fishery management decision-making process is generally low, particularly in small-scale fisheries (SSF). Within the overarching goal of improving fisheries governance, fishers’ participation is crucial. Yet, how can fishers participate in the decision-making processes which affect their actions, and to what extent do fisher associations represent their interests? These questions were tackled by means of an empirical case study in the “Tertúlia do Polvo” project, focusing on the octopus SSF in the Algarve region (south Portugal), where the octopus fishery is managed top-down with sporadic participation of fishers. During the study (2014 and 2015), seven participatory workshops (tertúlias) were held, involving fisher associations, management authorities and researchers, to propose and discuss management measures for the fishery. Also, a face-to-face questionnaire survey (121 valid replies) was undertaken with local fishers to gauge their opinions about the management measures proposed during the workshops. Results show a strong agreement between the outcomes achieved during the workshops and the main concerns and possible solutions identified by fishers. Taking into consideration the difficulty in structuring and assuring a transparent and effective participation of fishers in the management of their activity, the results obtained are promising. In this study, the use of a participatory process (restricted to a small group of stakeholders) combined with consultation (targeting a sample of the fisher population) allowed the validation of the overall results obtained. Such a methodological approach can be tried in other fishing communities to implement efficient and effective collaborative management, contributing to improved fisheries governance.
- Environmental and fishery-driven dynamics of the common octopus (Octopus vulgaris) based on time-series analyses from leeward Algarve, southern PortugalPublication . Sonderblohm, Carlos; Pereira, João; Erzini, KarimDynamic factor analysis was used to explore monthly landings per unit effort (LPUE) series of Octopus vulgaris and environmental variables recorded in the southwest Iberian Peninsula, south Portugal. Despite the large fluctuations in the octopus abundance series, results showed a strong aggregation pattern for the last 3 months of the year, possibly related to the input of new recruits to the fishery. The calculated common trend for the 12 months time-series presented significant correlations with autumn rainfall of the previous year (lag - 1), particularly for the October, November, and December series. Other important correlations were found for the Western Mediterranean Oscillation index (lag - 1), Ekman transport, summer river run-off (lag - 1), horizontal and vertical component of windstress, among others. The main trend describes a moderate steady increase in LPUE during the last 10 years, suggesting that octopus abundance has increased from 1990 to 2010. The strong correlations of the monthly octopus LPUE series, together with the annual life cycle, suggest that after environmentally controlled recruitment, population dynamics is largely fishery driven, resulting in strong seasonality in the landings.
- Dinâmica das pescas e gestão participativa do polvo vulgar (Octopus vulgaris) capturado pela frota de covos e alcatruzes no sul de PortugalPublication . Sonderblohm, Carlos; Erzini, Karim; Pereira, JoãoThe following PhD dissertation presents information on biological, ecological, socioeconomical and governmental aspects of the fishery of the common octopus (Octopus vulgaris), captured by pot and trap fishing fleets in the region of Algarve (Portugal), in the southwest of the Iberian Peninsula. The thesis work has been divided into two parts, Part One and Part Two. Part One addresses the fishery dynamics of the common octopus and its relationship with the life cycle of the species, especially those aspects concerning key reproductive stages such as spawning, para-larvae and fishing recruitment, and also its relationship with the environment. Part Two analyses the management of the fishery of the common octopus currently in force in Portugal, particularly in the Algarvian region. A series of workshops were held with stakeholders from this fishery, such as fishermen, scientists and government officials, with the purpose of discussing management approaches aimed to improve this fishery, for example the implementation of a seasonal closure in order to protect the reproduction of the species. Part One is sub-divided into two chapters, Chapter Two and Chapter Three, which precede the introduction or Chapter One. Chapter One gives an overview of the octopus fisheries around the world, the life cycle of the species and how it affects the management of the fishery, and challenges faced by the fishers and industry. Chapter Two emerges from the necessity of the fishermen to establish the time of the year that is deemed most suitable for implementing a ban on the fishery of the common octopus, in order to protect its reproduction and recruitment. This chapter aims to explain the relationship between the dynamics of the fishery and the octopus's life cycle. By means of multivariate statistical analysis of the last 25 years of data from fishing landing records at 12 main ports of the region, the most important factors linking the fishery dynamics of the octopus and its biology were identified. The results were used to construct an life cycle figure that can be used by fishermen, scientists, students, government officials, among others as a quick reference guide. Chapter Three investigate fishing landing data from the Port of Santa Luzia, one of the most important octopus ports in the Algarvian region. The use of statistical techniques such as Dynamic Factor Analyses (DFA) specifically intended for the analysis of time series including local oceanographic and environmental data is explored in order to find common trends and its relationship with environmental variables relevant to the selected fishing area. The results of these analyses reveal factors that affect the recruitment of the species in the Algarve. Part Two is sub-divided also into two chapters, Chapter Four and Chapter Five. Chapter Four begins with a description of the current socio-economic situation and governance model of the pot and trap octopus fisheries in the country. Using a time line approach, a retrospective of the evolution of this fishery during the last 50 years was developed. Common challenges associated with the steady increase of this fishery were identified. Chapter Five analyses ideas debated at seven participatory workshops, held between 2014 and 2015, on the management of the pot and trap octopus fishery in the Algarvian region. In these meetings, stakeholders (fishermen, marine biology researchers, scientists, representatives of government bodies and public institution, university students, among others) discussed proposals aimed to address current challenges, improve the management of the fishery of this resource, and develop a comanagement model that benefits all parties involved in the activity. These proposals were summarized in a handbook that is included as an annex at the end of this PhD dissertation. This paper concludes in Chapter Six with a general discussion about previous chapters and future research that are considered necessary as a result of this work.
- Participatory assessment of management measures for octopus vulgaris pot and trap fishery from southern PortugalPublication . Sonderblohm, Carlos; Guimarães, Maria H.; Pita, Cristina; Oliveira, M.R.; Pereira, João; Gonçalves, Jorge Manuel Santos; Erzini, KarimCo-management has shown promising results for the sustainable use of fishery resources. The common octopus (Octopus vulgaris) pot and trap fishery in the Algarve (Portugal) holds the potential for implementation of a co-management system. To explore this potential, seven participatory workshops took place between 2014-2015, bringing together 60 participants from 10 fishing associations and 16 fisheries management and research institutions. The exercise resulted in promising outcomes with regards to the possible implementation of a co-management system for the fishery. In the present work an overview of the outcomes of the participatory workshops is given and compared with initiatives worldwide. Among the management actions identified, some have direct impacts on the octopus' life cycle, while all target the same overall objective: to regulate fishing effort. In the informal setting of the workshops, a formal request was developed: the establishment of an annual closed season in the Algarve. This request was taken into consideration by the responsible management institution.