An ecological and fishing approach to support management decisions

Leitão, F., Monteiro, J. N., Cabral, P., Teodósio, M. A., & Roa-Ureta, R. H. (2023). Revealing the role of crab as bait in octopus fishery: An ecological and fishing approach to support management decisions. Marine Policy, 158, 1-11. [105878]. https://doi.org/10.1016/j.marpol.2023.105878 --- This study received Portuguese National Funding from MAR2020 project CRUSTAPANHA (MAR-01.04.02-FEAMP-0005 CRUSTAPANHA). FL has received Portuguese national funds from FCT within the contract program DL57/2016/CP1361/CT0008 and FCT 2022.04803. CEECIND. JNM received an FCT PhD fellowship SFRH/BD/06336/2021. This study received Portuguese national funds from FCT - Foundation for Science and Technology through projects UIDB/04326/2020, UIDP/04326/2020 and LA/P/0101/2020. Authors would like to acknowledge all fishers’ associations that participated in CRUSTAPANHA project and helped the completion of the study: AAPF- Associação de Armadores e Pescadores da Fuseta (Fuseta); Associação Armalgarve Polvo Organização De Produtores (Quarteira); OLHAOPESCA Organização de Produtores de Pesca do Algarve, C.R.L. (Olhão). We acknowledge DGRM for fisheries data provided and for granting licenses for researchers onboard fishing vessel; To the coast guards forces of the following ports: Capitania do Porto de Albufeira; Capitania do Porto de Faro; Capitania do Porto de Olhão; Capitania do Porto de Lagos; Capitania do Porto de Tavira; We would like to acknowledge specific captains due to their role in the study, namely: Ricardo Santana; Francisco Molina; Arlindo da Silva Correia; Paulo Guerreiro. We would like to acknowledge all the members of ECOREACH group that help in the measurement of the octopus specimens, namely Andreia Ovelheiro, Daniela Nobre, Juan Bueno-Pardo and Miguel PintoIn southern Portugal, artisanal octopus fisheries play an important socioeconomic role. Live crab bait in traps was used up to 2010 and banned in 2012. Such regulation, based on co-management advice, was not established under a scientific fundament. As a result, a long-standing controversy ensued with some fishing associations claiming that live crab bait increased fishing effort and exploitation rates and therefore risked the octopus stock status, while other fishers denied all these alleged impacts. The issue has not been resolved so far due to lack of scientific studies. In this study, we resolve the controversy conducting experimental fishing to determine by-catch and octopus catch rates using live crab bait versus other types of baits based on fish and assess the stock status of octopus over-time with constant parameters (hypothesis of no effect of the use of live crab bait) versus time-varying parameters (hypothesis of raised exploitation rates and riskier stock status). Bycatch was very low regardless of bait type. Our experimental fishing trials showed that fish-based baits increase bycatch and octopus catch rates. Stock assessment models showed that exploitation rates and stock status do not worsen in years of use of crab bait. We conclude that the use of crab bait in octopus fishery does not lead to increased exploitation rate or risks for stock sustainability status. Other considerations involving fishing costs and fishing operations further highlight the advantages of lifting the ban on the use of live crab bait in the Algarve octopus fishery.publishersversionpublishe

Actividades realizadas pelo CCPA no decorrer da XII Expedição Científica do Departamento de Biologia - Pico/2005

XII Expedição Científica do Departamento de Biologia - Pico 2005.O Centro de Conservação e Protecção do Ambiente (CCPA) do Departamento de Biologia (DB) promove acções de Educação Ambiental junto das populações. Neste âmbito, a nossa deslocação à ilha do Pico teve como principal objectivo realizar acções de sensibilização e promoção da melhoria do estado de conservação do meio ambiente. As nossas acções tiveram como público-alvo sobretudo crianças e jovens, e como tal pretendeu-se que as mesmas tivessem lugar na Ecoteca do Pico e nas Escolas Básicas e Secundárias locais

Winter river discharge may affect summer estuarine jellyfish blooms

Dams alter the natural dynamics of river inflow, disrupting biological processes in downstream ecosystems, as observed in the Guadiana estuary (SW Iberian Peninsula, Europe). Here, significant interannual fluctuations in the densities of jellyfish occur during summer, likely due to changes in winter river discharge. Therefore, this study aimed to quantify the relationship between winter river inflow and the abundance of jellyfish in the Guadiana estuary. In addition, the budding and growth of Aurelia aurita polyps, one of the bloom-forming species present in the estuary, were determined at different combinations of constant temperature and salinity. The response of polyps and ephyrae to short-term, low-salinity pulses was also quantified. Maximum winter river discharge and maximum abundance of estuarine medusa (bloom indicator) showed a significant negative correlation. Under constant conditions, polyps showed increased mortality when water temperature was higher than 23°C and salinity was lower than 23, and died when exposed to a short-term, low-salinity pulse (≤3). After exposure to freshets, polyp budding and feeding rates decreased by 69% and 32%, respectively, when salinity reached values as low as 10. Ephyrae died when salinity was lower than 10, and feeding rates decreased by 88% when salinity was 17, compared with full marine conditions. In conclusion, winter freshwater discharge may regulate the strength of estuarine jellyfish blooms, impairing the survival or condition of polyps and ephyrae during late winter or early spring. River basin managers should consider the prescription of freshets to prevent jellyfish blooms from disrupting ecosystem services (e.g. fisheries, tourism)

Environmental Markers of Plastics and Microplastics

The slow reaction rates to chemical and photochemical degradation are well-known properties of plastics. However, large plastic surfaces exposed to environmental conditions release particles and compounds that affect ecosystems and human health. The aim of this work was to identify compounds associated with the degradation of polyethylene (PE), polystyrene (PS), and polyvinyl chloride (PVC) microplastics (markers) on silica and sand and evaluate their use to screen microplastics on natural sand. Products were identified by using targeted and untargeted LC-HRMS analysis. All polymers underwent chemical oxidation on silica. PE released dicarboxylic acids (HO C-(CH ) -CO H ( = 4-30), while PS released / -chalcone, -dypnone, 3-phenylpropiophenone, and dibenzoylmethane. PVC released dicarboxylic acids and aromatic compounds. Upon irradiation, PE was stable while PS released the same compounds as under chemical oxidation but at lower yields. Under the above condition, PVC generated HO C-[CH -CHCl] -CH -CO H and HO C-[CH -CHCl] -CO H ( = 2-19) dicarboxylic acids. The same products were detected on sand but at a lower concentration than on silica due to better retention within the pores. Detection of markers of PE and PS on natural sand allowed us to screen microplastics by following a targeted analysis. Markers of PVC were not detected before or after thermal/photo-oxidation due to the low release of compounds and limitations associated with surface exposure/penetration of radiation