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- Variability in Carcinus maenas Fecundity Along lagoons and estuaries of the Portuguese coastPublication . N. Monteiro, J.; Ovelheiro, Andreia; Ventaneira, Ana M.; Vieira, Vasco; Teodosio, Maria; Leitão, FranciscoAlthough Carcinus maenas as a species is widely studied, research focusing on fecundity is still scarce. The main objective of this study was to evaluate size-fecundity relationships across diferent lagoons and estuaries, along the Portuguese coast, to understand how the local environment afects reproductive patterns. Between 2019 and 2020, ovigerous females were collected from the Southern (Ria Formosa and Ria de Alvor), Central (Rio Sado) and Northern regions (Ria de Aveiro) of Portugal, and the fecundity of each female was estimated by counting and weighing eggs. Morphometric relationships (carapace width–egg counting; egg counting–egg weight; body wet weight–egg weight; carapace width–body wet weight) were inferred from 180 egg-bearing females with a carapace width between 26.96 and 61.25 mm. A positive correlation between fecundity and the morphological parameters was observed. Diferences in fecundity were found among all systems, from northern to southern Portugal, varying between 22121 and 408538 eggs per female. Furthermore, a regional gradient was observed across regions, with lower temperature estuaries (Ria de Aveiro) displaying an increase in fecundity. The fecundity in Rio Sado was also afected by salinity. Fecundity diferences across regions were associated with hydrodynamics, temperature, and salinity diferences among systems. No statistically signifcant diferences were observed between Carapace Width—Body Wet Weight regressions performed in each studied system, indicating that, contrary to fecundity, the somatic growth of C. maenas is not afected by latitudinal or environmental conditions.
- Reproductive traits of the African mud crab (Panopeus africanus) on the South Portuguese coastPublication . N. Monteiro, J.; Ovelheiro, Andreia; Pinto, Miguel; Teodosio, Maria; Leitão, FranciscoSpecies with high economic relevance are widely studied in contrast with low economic relevance species such as Panopeus africanus, a small crab with a wide distribution along the eastern Atlantic coast, which remains poorly studied in regarding to the biological and ecological issues. Knowledge of reproductive patterns is essential to understand populations dynamics and species biological life-cycle traits. The main objective of the present research was to study the reproductive patterns of P. africanus. The population size structure, maturation stages and gametogenic development aspect, size at maturation, reproductive periods and morphometric-fecundity relationships of P. africanus in the southern Portuguese coast (Ria Formosa) was analysed. Crabs were sampled monthly, from January 2019 to December 2021, with traps and hand collected. The crab's carapace width (CW) ranged between 7 to 52 mm, and it was observed that in smaller and larger CW size classes, the proportion of males was higher, however in intermediate CW size classes the sex ratio was near 1:1. The gonads development was characterized based on histological analysis. Males presented four maturity developmental stages where two stages were immature and two were mature. Females presented six maturity developmental stages, where two stages were immature, and four stages were mature. Regardless of sex, the mean maturity size was 20 mm CW. A high percentage of mature individuals was observed throughout the year however, in the colder months the percentage of mature individuals was lower. Additionally, ovigerous females were only observed in the warmer months, pointing to a short breeding period occurring in the warmer months. Fecundity ranged between 12368 and 84140 eggs/female, following a positive correlation between CW/egg number. These novel results allowed to shed light on reproductive patterns of P. africanus population inhabiting the southern Portuguese coast, contributing also to a better understanding of the basic reproductive biology of this crab populations.
- Climate change vulnerability assessment of the main marine commercial fish and invertebrates of PortugalPublication . Bueno-Pardo, Juan; Nobre, Daniela; Monteiro, J. N.; Sousa, Pedro M.; Costa, Eudriano; Baptista, Vânia; Ovelheiro, Andreia; Vieira, Vasco; Chicharo, Luis; Gaspar, Miguel; Erzini, Karim; Kay, Susana; Queiroga, Henrique; Teodosio, Maria; Leitão, FranciscoThis is the first attempt to apply an expert-based ecological vulnerability assessment of the effects of climate change on the main marine resources of Portugal. The vulnerability, exposure, sensitivity, adaptive capacity, and expected directional effects of 74 species of fish and invertebrates of commercial interest is estimated based on criteria related to their life-history and level of conservation or exploitation. This analysis is performed separately for three regions of Portugal and two scenarios of climate change (RCP 4.5 and RCP 8.5). To do that, the fourth assessment report IPCC framework for vulnerability assessments was coupled to the outputs of a physical-biogeochemical model allowing to weight the exposure of the species by the expected variability of the environmental variables in the future. The highest vulnerabilities were found for some migratory and elasmobranch species, although overall vulnerability scores were low probably due to the high adaptive capacity of species from temperate ecosystems. Among regions, the highest average vulnerability was estimated for the species in the Central region while higher vulnerabilities were identified under climate change scenario RCP 8.5 in the three regions, due to higher expected climatic variability. This work establishes the basis for the assessment of the vulnerability of the human activities relying on marine resources in the context of climate change.
- Macro and microscopic maturation stage key of green crab (Carcinus maenas, Linnaeus 1758): reproductive cycle and differences among estuarine systemsPublication . Ovelheiro, Andreia; N. Monteiro, J.; Gonçalves, Patrícia; Campinho, Marco António; Maia, Francisco; Teodosio, Maria; Leitão, FranciscoGonadal histology is a helpful tool to validate species' macroscopic maturity stages in fisheries biology. Regardless of the many studies on Carcinus maenas, there are still few concerning gonads tissue histology and description of maturity stages. In Portugal, information regarding this species' biology to help support the regulation of crab fisheries, including the minimum landing size, has not yet been defined. In this work, the macro and microscopic characteristics of the reproductive cycle of C. maenas, oogenesis, and spermatogenesis development stages along the Portuguese coast are described, and a new macroscopic scale based on the histological analyses is suggested. During 2019 and 2020, adult C. maenas (both males and females) were collected from the Ria de Aveiro estuary, Rio Sado estuary, and Ria Formosa lagoon, respectively, North, Center, and South Portugal. No-significant differences (P > 0.05) were observed in carapace width and individual weight between all systems. Significant differences (P < 0.05) were observed in gonad weight, gonadosomatic index, and Fulton's condition index between the Rio Sado estuary and Ria Formosa lagoon. Furthermore, significant differences (P < 0.05) in the oocyte diameter between the northern and southernmost locations suggest a geographic variation related to the local environmental conditions of each system. Principal component analysis (PCA) revealed maturity stage and carapace width an association, and a similar morphometry between Ria de Aveiro and Ria Formosa. Temperature was correlated to both maturity stage and carapace width in Ria de Aveiro and Ria Formosa. From the histological analysis and based on microscopic criteria, it was observed that females previously classified within the late macroscopic development stage 2 should be considered mature, so a classification change in the current ovary's developmental stage is proposed. These findings can allow fisheries researchers to reclassify the estimations of maturity ogives and help support the regulation of this species' fishery. The proposed macroscopic scale was validated by histological analyses and can be used elsewhere.
- Implications of warming on the morphometric and reproductive traits of the Green Crab, Carcinus maenasPublication . N. Monteiro, J.; Bueno-Pardo, Juan; Pinto, Miguel; Pardal, Miguel A.; Martinho, Filipe; Miguel de Sousa Leitão, FranciscoUnderstanding the relationship between environmental temperature and the biological traits of organisms is fundamental to inferring the potential impacts of climate change. In the case of marine poikilotherm species, seawater temperature is one of the main driving forces of biological processes, with consequences at higher levels of organization such as population and ecosystem. In this study, we analysed differences in maximum carapace width (CWmax), size at maturation, relative size at maturation, and duration of the reproductive season for the green crab (Carcinus maenas) along a temperature gradient. An extensive review of bibliographic data was performed on studies published between 1962 and 2020, gathering C. maenas data from 55 different populations, spread over 20 degrees of latitude and 14.2 °C of sea surface temperature (SST). In addition, green crab data were collected at five different lagoons and estuaries along the continental Portuguese coast. The relationship between average SST and CWmax, age of maturation, reduction of size at maturation, and duration of egg bearing was analysed to understand the role of SST in driving variation in these C. maenas characteristics across a latitudinal gradient. There was a significant relationship between SST and CWmax for males and SST and CW of females at maturation, respectively. The results extrapolate for each local projected temperature increase caused by climate change and suggest an effect on the morphometric and reproductive traits of C. maenas across regions. These changes comprise an overall reduction in C. maenas body size, an enlargement of the reproductive season, a shortening in the duration of larval developmental time, and a decrease in the relative size of crabs at maturation. Secondary consequences on the fecundity and connectivity of populations are discussed.
- Revealing the role of crab as bait in octopus fishery: an ecological and fishing approach to support management decisionsPublication . Leitão, Francisco; Monteiro, J. N.; Cabral, Pedro; Teodosio, Maria; Roa-Ureta, Ruben H.In 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 bycatch 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.
- Effect of bait type on the octopus fishery in Algarve, Southern PortugalPublication . Leitão, Francisco; Bueno-Pardo, Juan; Ovelheiro, Andreia; Monteiro, J. N.; Nobre, Daniela; Teodosio, MAIn Algarve, southern Portugal, a fishery regulation was established forbidding the use of live crab as bait for the octopus fishing. Such a regulation was not established under a scientific fundament. The objective of this work was to identify if using live crab as bait affects the octopus fishery. Time series (1989–2015) were analysed in order to calculate octopus catch rates (as Landing Per Unit Effort or LPUE) and revenues (as revenue per unit effort or RPUE) before and after the crab bait ban in 2009 and also by bait type (crab and fish) before ban. Overall, total annual fishing effort decreased as result of the decreasing number of boats and fishing days in the local and coastal fleets. After the ban both the LPUE and RPUE increased, with total landings showing no change through time but mean landings per boat increased. Between 1989 and 2009, the mean monthly fishing effort in the coastal fleet was higher when crab bait was used (3.88%) in comparison to using fish bait (0.3%). This result is superimposed by the large inter annual variability between the local and coastal fleets (39.11%). In consequence, no substantial evidence was found indicating that crab bait produced high octopus catch rates, while fishing effort indicated that such high octopus catch rate and revenue increase was due to the decline of number of boats and fishing effort, that was decreasing significantly regardless of the bait type and fleet before to crab ban, and not to the bait type used during this period.
- Ecological sensitivity and vulnerability of fishing fleet landings to climate change across regionsPublication . Albo Puigserver, Marta; Bueno-Pardo, Juan; Pinto, Miguel; N. Monteiro, J.; Ovelheiro, Andreia; Teodosio, Maria; Leitão, FranciscoThe degree of exposure of fishing communities to environmental changes can be partially determined by the vulnerability of the target species and the landings composition. Hence, identifying the species that ecologically most contribute to the vulnerability of the landings are key steps to evaluate the risk posed by climate change. We analyse the temporal variability in intrinsic sensitivity and the ecological vulnerability of the Portuguese fisheries landings, considering the species proportions derived both from the weights and revenues. To account for the diversification of species of each fleet, we explored the species dependence of the fishery in combination with the vulnerability of them. The analyses were carried out separately for three fleet typologies and three regions. Opposite to what has been observed at a global scale, the ecological sensitivity of the fisheries landings between 1989 and 2015 did not display a decline across areas or fishing fleets. Considering each fleet independently, for trawling, where average vulnerability was lower than in the other fleets, the sensitivity of the landings increased since the 2000s. On the other hand, the high vulnerability found in multi-gear fleets was compensated by diversification of the species caught, while purse-seine fleets targeted low vulnerability species but presented a high fishery dependence on few species. The results highlight the importance of combining information on ecological vulnerability and diversification of fishing resources at a regional scale while providing a measure of the ecological exposure to climate change.
- Eco-socio-economic vulnerability assessment of Portuguese fisheries to climate changePublication . Pinto, Miguel; Albo-Puigserver, Maria; Bueno-Pardo, Juan; N. Monteiro, J.; Teodosio, Maria; Leitão, FranciscoUnderstanding ecological, and socio-economical vulnerabilities is fundamental towards developing and implementing regional adaptation strategies to climate change. The Portuguese coast is situated in a transition zone between temperate ecosystems to the north, and subtropical with Mediterranean characteristics, to the south, with distinct oceanographic regions (north, centre, and south), fish assemblages and socioeconomic realities of fish communities across these regions. We develop a framework to assess fisheries climate vulnerability in each port. A total of 32 ecological and socio-economic indicators were used to measure exposure, sensitivity, and adaptive capacity of the fishing sector to climate change by combining i) environmental projections ii) information from fishing communities (surveys at ports) and iii) landings and socio-economic data from official statistics offices. The vulnerability to climate change across regions, and its expected impact on fishing fleets and local communities, was low-moderate. Such information will enable fishing communities and decision makers to respond to expected climate change effects and direct/indirect associated activities. This framework comprises background information for developing mandatory EU climate adaptation plans that aim to improve the resilience of fisheries socio-economic systems.
- Influence of oceanic and climate conditions on the early life history of European seabass Dicentrarchus labraxPublication . Pinto, Miguel; N. Monteiro, J.; Crespo, D.; Costa, F.; Rosa, J.; Primo, A. L.; Pardal, M. A.; Martinho, F.Understanding how marine fish early-life history is affected in the long-term by environmental and oceanographic factors is fundamental given its importance to population dynamics and connectivity. This work aimed at determining the influence of these processes on the interannual variability in hatch day and early-life growth patterns of European seabass, over a seven-year period (2011-2017) in the Atlantic Iberian coast. To accomplish this, otolith microstructure analysis was used to determine seabass hatch day and to develop early-growth correlations. In most years, hatching occurred from February to April, with two exceptions: in 2012, hatching started in early-January, and in 2016 an exceptionally long hatching period was registered. Using generalized additive models (GAM), we observed that sea surface temperature (SST), the North Atlantic Oscillation index (NAOi) and Chlorophyll-a (Chla) were the main drivers behind the inter-annual variability in seabass hatch day. Analysis of correlations between growth increments allowed assessing important periods of seabass growth and how future growth is affected. Since seawater temperature is among the main drivers for seabass recruitment and growth, its life cycle may be hampered due to ocean warming and an increasingly unstable climate, with consequences for the natural marine stocks and their harvest.