Effects of hook and bait on targeted and bycatch fishes in an equatorial atlantic pelagic longline fishery

We examined the effects of different hook style and bait type combinations on the catches of targeted, bycatch, and discarded fishes in equatorial Atlantic waters. In total, 221 longline sets (>305,000 hooks) were deployed from Portuguese pelagic longline vessels (SELECT -PAL Project) during the February–October fishing season. Three different hook styles and two bait types were tested: the traditional J-hook was compared to two circle hooks (one non-offset and one with 10° offset), and squid bait was compared to mackerel. Catch per unit effort (CPU Es) were calculated and compared between the different hook style and bait type combinations, which indicated that the effects of hook style and bait on the CPU Es were species-specific. For example, swordfish CPU Es were higher with J-hooks baited with squid, while for targeted tunas and blue shark only the bait effect was significant, but with opposite effect (i.e., higher catches of tuna with squid bait and higher catches of blue shark with mackerel bait). For the discarded species, at-haulback mortality was also species-specific. Proportions of alive vs dead specimens at time of fishing gear retrieval did not vary significantly by hook style or bait type combinations. The total retained catch was analyzed in value per unit effort (VPU E), and indicated losses in fishery revenue when mackerel was used instead of squid, but not when circle hooks were used instead of J-hooks.info:eu-repo/semantics/publishedVersio

Distribución vertical y horizontal de larvas de Monodaeus couchii frente a la costa sur de Portugal

A strong understanding of larval distribution and abundance is of major value in delineating the location and size of a breeding population of deep-sea species such as Monodaeus couchii. In this study, vertical distribution of the larvae of a brachyuran crab, M. couchii, was assessed during two week-long cruises conducted at the end of January 2006 and 2007 off the South Coast of Portugal. Larvae were collected by oblique plankton hauls with a Longhurst-Hardy Plankton Recorder from the surface to 300 m. Abundance and distribution of zoeae I and II were correlated during both years. For all stages, abundance decreased with depth during the day while it increased with depth at night; the larvae thus displayed reverse diel vertical migration. Abundance of zoeae I and II was correlated with chlorophyll a levels, whereas those of later stages were correlated with neither physical parameters (chlorophyll a, temperature or salinity) nor each other. An ontogenic shift in vertical distribution explained the results; earlier zoeal stages remain in the food-rich upper water column while later stages were not correlated with any physical parameters (i.e. chlorophyll a, salinity or temperature) and migrated to the bottom for settlement.El conocimiento de la distribución y abundancia larval es de vital importancia para comprender la localización y tamaño de la población reproductora adulta en especies abisales como Monodaeus couchii. En este estudio, la distribución vertical de las larvas de un cangrejo braquiuro, M. couchii, se evaluó durante dos campañas de una semana de duración al final de enero de 2006 y 2007, frente a la costa sur de Portugal. Las larvas se recogieron por pescas oblicuas de plancton con un “Longhurst-Hardy Plankton Recorder” (LHPR) desde la superficie hasta 300 m de profundidad. La abundancia y distribución de las zoeas I y II fueron correlacionadas para cada uno de los años de estudio. Para todos los estadios larvares la abundancia disminuyó con la profundidad durante el día, mientras que se incrementó con la profundidad durante la noche, mostrando por tanto un patrón de migración vertical inverso. La abundancia de zoeae I y II se correlacionó con los niveles de clorofila a, mientras que la abundancia de estadios posteriores no mostró correlación alguna con los parámetros físicos (clorofila a, temperatura o salinidad), ni entre sí. Estos resultados indican un cambio ontogénico en la distribución vertical de las larvas; los primeros estadios de zoea permanecen en la zona superficial de la columna de agua rica en alimento, mientras que las ultimas etapas que no mostraron correlación con los parámetros físicos (i.e. clorofila a, salinidad o temperatura) migran a zonas más profundas para el recrutamento

Modeling age and growth of the bigeye thresher (Alopias superciliosus) in the Atlantic Ocean

The bigeye thresher (Alopias superciliosus) is a pelagic shark captured as bycatch in pelagic longline fisheries. Important information on its biology is still missing, especially from the Atlantic Ocean. In all, 546 vertebrae collected by fishery observers between 2007 and 2009 were used to estimate age and growth parameters for this species in the Atlantic Ocean. The size composition was 102–265 cm fork length (FL) for females and 94–260 cm FL for males. The estimated ages ranged from 0 to 25 years for both sexes. From the 5 growth models used, the 3-parameter von Bertalanffy growth model, reparameterized to estimate length at birth (L0), produced the best results. The estimated parameters were asymptotic maximum length (Linf)=284 cm FL, growth coefficient (k)=0.06/year, and L0=109 cm FL for females and Linf=246 cm FL, k=0.09/year, and L0=108 cm FL for males. Although differences between hemispheres indicate slower growth rates in the South Atlantic Ocean, these differences may also have been caused by the lower sample size and larger specimen sizes for the Southern Hemisphere. The estimated growth coefficients are among the lowest found for the Alopiidae, highlighting the bigeye thresher’s slow growth and consequent low resilience to fishing pressure

Stakeholder analysis in the portuguese artificial reef context: winners and losers

Nesta análise de intervenientes relativa ao programa de recifes artificiais (RAs) localizado na costa do Algarve (Sul de Portugal continental) foram identificados 21 grupos de atores distintos. Os intervenientes foram classificados em 3 grupos: primários, secundários e externos. Verificou-se que o interesse dos intervenientes face às estruturas recifais (interação) pode ser do tipo privado, público ou cooperativo. Na análise foram identificados os impactos do projeto sobre os intervenientes e o poder destes para influenciar os resultados do programa recifal. Foram definidas quais as interações e possíveis atitudes e comportamento dos intervenientes em relação aos RAs. Finalmente, todos os grupos de intervenientes foram classificados de acordo com o grau de envolvimento esperado ao longo das diferentes fases do programa recifal. O propósito desta análise de intervenientes foi identificar ganhadores e perdedores relacionados com a criação dos recifes artificiais. Verificou-se que a maioria dos grupos de intervenientes pode ser afetado positivamente, mas existem quatro grupos supostamente afetados negativamente. Contudo, acredita-se que estes últimos não constituem um risco sério ao desenvolvimento do programa recifal no decurso do seu tempo de vida.In this stakeholder analysis related to the artificial reef (AR) program located in the Algarve (Southern Portugal mainland) 21 different stakeholder clusters were identified. Stakeholders were classified as primary, secondary and external. It was found that stakeholder interaction with the structures can be of private, public or cooperative interest. In the analysis there were also identified and mapped the impact of the program on stakeholders and their power to influence the ARs' outcomes. Stakeholders' interactions with the ARs were studied, along with their likely attitudes and behavior towards the man-made structures. Finally, all stakeholder clusters were classified according to their expected degree of involvement throughout the different AR stages. The purpose of this stakeholder analysis was to find out winners and losers connected with the reef deployment. It was found that most stakeholder clusters were affected positively, but also four clusters affected negatively. However, it is believed that those that may be affected negatively do not pose a serious threat to the expected AR development along its lifetime

An overview of the hooking mortality of elasmobranchs caught in a swordfish pelagic longline fishery in the Atlantic Ocean

Hooking (or “at-haulback”) fishing mortality was analysed in elasmobranchs captured by Portuguese longliners targeting swordfish in the Atlantic Ocean. Information was collected by on-board fishery observers who monitored 834 longline fishing sets between August 2008 and December 2011, and recorded information on 36,067 elasmobranch specimens from 21 different taxa. The hooking mortality proportions were species-specific, with some species having relatively high percentages of live specimens at time of haulback (e.g., blue shark, crocodile shark, pelagic stingray, manta, devil and eagle rays), while others had higher percentages of dead specimens (e.g., smooth hammerhead, silky shark, bigeye thresher). For the most captured species, logistic GLMs were carried out to compare the mortality rates between sexes, specimen sizes and the regions of operation of the fleet. The sex-specific proportions of hooking mortality were significantly different for blue and crocodile sharks, with the males of both species having higher proportions of hooking mortality than the females. Specimen size was significant for predicting the hooking mortality for blue and shortfin mako sharks: in both cases, the larger specimens had lower odds of dying due to the fishing process. There were differences in the hooking mortality depending on the region of operation of the fleet, but those differences were also species-specific. For blue and crocodile sharks, the hooking mortality was higher in the Equatorial and southern Atlantic areas (when compared to the NE Atlantic region), while the opposite was observed for the shortfin mako, with lower mortality rates in the NE tropical area compared with the other regions. The results presented in this paper can be integrated into future ecological risk assessment analysis for pelagic elasmobranchs. Furthermore, the new information can be used to evaluate the impact of recent recommendations prohibiting the retention of some vulnerable elasmobranch species

A Quantitative analysis of pulsed signals emitted by Wild Bottlenose Dolphins

Common bottlenose dolphins (Tursiops truncatus), produce a wide variety of vocal emissions for communication and echolocation, of which the pulsed repertoire has been the most difficult to categorize. Packets of high repetition, broadband pulses are still largely reported under a general designation of burst-pulses, and traditional attempts to classify these emissions rely mainly in their aural characteristics and in graphical aspects of spectrograms. Here, we present a quantitative analysis of pulsed signals emitted by wild bottlenose dolphins, in the Sado estuary, Portugal (2011-2014), and test the reliability of a traditional classification approach. Acoustic parameters (minimum frequency, maximum frequency, peak frequency, duration, repetition rate and inter-click-interval) were extracted from 930 pulsed signals, previously categorized using a traditional approach. Discriminant function analysis revealed a high reliability of the traditional classification approach (93.5% of pulsed signals were consistently assigned to their aurally based categories). According to the discriminant function analysis (Wilk's Λ = 0.11, F3, 2.41 = 282.75, P < 0.001), repetition rate is the feature that best enables the discrimination of different pulsed signals (structure coefficient = 0.98). Classification using hierarchical cluster analysis led to a similar categorization pattern: two main signal types with distinct magnitudes of repetition rate were clustered into five groups. The pulsed signals, here described, present significant differences in their time-frequency features, especially repetition rate (P < 0.001), inter-click-interval (P < 0.001) and duration (P < 0.001). We document the occurrence of a distinct signal type-short burst-pulses, and highlight the existence of a diverse repertoire of pulsed vocalizations emitted in graded sequences. The use of quantitative analysis of pulsed signals is essential to improve classifications and to better assess the contexts of emission, geographic variation and the functional significance of pulsed signals.Fundação para a Ciência e Tecnologia - FCTinfo:eu-repo/semantics/publishedVersio

Recovery of substrates and macro-benthos after fishing trials with a new Portuguese clam dredge

The effect of dredging on bottom structure was assessed, to estimate the damage inflicted on the benthic macrofauna left on the dredge path and to evaluate aggregations of scavengers within the track. Sediment suspended during dredging rapidly resettled both on sand and sandy-mud bottoms. Dredge tracks were deeper on sandy-mud sediments and persisted longer than in sandy sediments. The disappearance of tracks in both sediment types depended both on current strength and wave action. Damage and mortality induced by dredging on the macrobenthic animals left on the dredge path was relatively low. Post-fishing diver observations showed that damaged animals left on the dredge path rapidly attracted scavengers, mainly Ophiura albida. Immediately after the tow ophiuras reached densities 8 times greater in the track region than in the background. However, they dispersed again rapidly because only few damaged fauna were available on the dredge tracks. Undamaged or slightly damaged shellfish started to rebury immediately after escaping from the dredge

Compound-specific stable isotope analysis of amino acids in pelagic shark vertebrae reveals baseline, trophic, and physiological effects on bulk protein isotope records

© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Magozzi, S., Thorrold, S. R., Houghton, L., Bendall, V. A., Hetherington, S., Mucientes, G., Natanson, L. J., Queiroz, N., Santos, M. N., & Trueman, C. N. Compound-specific stable isotope analysis of amino acids in pelagic shark vertebrae reveals baseline, trophic, and physiological effects on bulk protein isotope records. Frontiers in Marine Science, 8, (2021): 673016, https://doi.org/10.3389/fmars.2021.673016.Variations in stable carbon and nitrogen isotope compositions in incremental tissues of pelagic sharks can be used to infer aspects of their spatial and trophic ecology across life-histories. Interpretations from bulk tissue isotopic compositions are complicated, however, because multiple processes influence these values, including variations in primary producer isotope ratios and consumer diets and physiological processing of metabolites. Here we challenge inferences about shark tropho-spatial ecology drawn from bulk tissue isotope data using data for amino acids. Stable isotope compositions of individual amino acids can partition the isotopic variance in bulk tissue into components associated with primary production on the one hand, and diet and physiology on the other. The carbon framework of essential amino acids (EAAs) can be synthesised de novo only by plants, fungi and bacteria and must be acquired by consumers through the diet. Consequently, the carbon isotopic composition of EAAs in consumers reflects that of primary producers in the location of feeding, whereas that of non-essential amino acids (non-EAAs) is additionally influenced by trophic fractionation and isotope dynamics of metabolic processing. We determined isotope chronologies from vertebrae of individual blue sharks and porbeagles from the North Atlantic. We measured carbon and nitrogen isotope compositions in bulk collagen and carbon isotope compositions of amino acids. Despite variability among individuals, common ontogenetic patterns in bulk isotope compositions were seen in both species. However, while life-history movement inferences from bulk analyses for blue sharks were supported by carbon isotope data from essential amino acids, inferences for porbeagles were not, implying that the observed trends in bulk protein isotope compositions in porbeagles have a trophic or physiological explanation, or are suprious effects. We explored variations in carbon isotope compositions of non-essential amino acids, searching for systematic variations that might imply ontogenetic changes in physiological processing, but patterns were highly variable and did not explain variance in bulk protein δ13C values. Isotopic effects associated with metabolite processing may overwhelm spatial influences that are weak or inconsistently developed in bulk tissue isotope values, but interpreting mechanisms underpinning isotopic variation in patterns in non-essential amino acids remains challenging.The internship of SM at the Woods Hole Oceanographic Institution was funded by the School of Ocean and Earth Science at University of Southampton. Stable isotope analyses were paid by CT and ST research budgets and SM Ph.D. and placement funding

O estigma da perda de um emprego formal no Brasil

We investigate if the labor market stigmatizes fired workers, by comparing their trajectories with individuals who lost their jobs after the establishments they used to work closed down. Using RAIS data for formal workers, we find that being fired significantly reduces the chances of finding a new formal job, and even when the individual succeed in doing so, he/she receives an initial wage 10% lower than his/her counterpart from a closed establishment. These results are robust to different estimation methods and sets of controls in the regressions

Using zeta-potential measurements to quantify peptide partition to lipid membranes

© The Author(s) 2011. This article is published with open access at Springerlink.com.Open Access: This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.Many cellular phenomena occur on the biomembranes. There are plenty of molecules (natural or xenobiotics) that interact directly or partially with the cell membrane. Biomolecules, such as several peptides (e.g., antimicrobial peptides) and proteins, exert their effects at the cell membrane level. This feature makes necessary investigating their interactions with lipids to clarify their mechanisms of action and side effects necessary. The determination of molecular lipid/water partition constants (Kp) is frequently used to quantify the extension of the interaction. The determination of this parameter has been achieved by using different methodologies, such as UV-Vis absorption spectrophotometry, fluorescence spectroscopy and ζ-potential measurements. In this work, we derived and tested a mathematical model to determine the Kp from ζ-potential data. The values obtained with this method were compared with those obtained by fluorescence spectroscopy, which is a regular technique used to quantify the interaction of intrinsically fluorescent peptides with selected biomembrane model systems. Two antimicrobial peptides (BP100 and pepR) were evaluated by this new method. The results obtained by this new methodology show that ζ-potential is a powerful technique to quantify peptide/lipid interactions of a wide variety of charged molecules, overcoming some of the limitations inherent to other techniques, such as the need for fluorescent labeling.This work was partially supported by project PTDC/QUI/ 69937/2006 from Fundação para a Ciência e Tecnologia-Ministério da Ciência, Tecnologia e Ensino Superior (FCT-MCTES, Portugal), and by Fundação Calouste Gulbenkian (Portugal). JMF and MMD also thank FCT-MCTES for grants IMM/BT/37-2010 and SFRH/BD/41750/2007, respectively