69 research outputs found
Ecological, Social and Economic Aspects of Italian Marine Spearfishing Tournaments (2009-2020)
Marine recreational spearfishing is practiced by a small proportion of recreational fishers and ecological, social and economic aspects of such activities are poorly understood with respect to recreational angling. The Italian Federation of Sport Fishing and Underwater Activities (FIPSAS) started in 2009 the collection of catch data related to Italian spearfishing tournaments. Here, we provide the first snapshot of this catch data regarding 48 tournaments organized in 29 different Italian localities from 2009 to 2020. We also developed a survey to collect social and economic information that has been administrated to participants to the tournaments. We retrieved 8843 specimens caught by spearfishers, which accounted for 33 species and a total biomass of 5665 kg (mean individual mass ± standard error; 0.64 ± 0.01 kg). The five most frequently species represented 78% of the specimens caught (white seabream, Diplodus sargus 48%; brown wrasse, Labrus merula 12%; brown meagre, Sciaena umbra 9%, green wrasse, Labrus viridis 5%; salema, Sarpa salpa 4%). The overall catch per unit effort for all the tournaments was 0.47 ± 0.01 kg/spearfisher/h, and we showed interesting effects of type of tournaments and type of displacement on it. We also assessed the accuracy of participants to catch fish in accordance to tournaments-specific minimum weight limits. The five most caught species showed that spearfishers committed errors around 50 g below the weight limit. The survey showed that spearfishers participating to tournaments are trophy-fish oriented (i.e., they would rather catch one or two big fish than ten smaller fish), but not particularly catch oriented (i.e., they are just as happy if they do not shoot the fish they see and a fishing trip can be successful even if no fish are caught). Regarding the motives for fishing, they fish for experiencing adventure, excitement and new and different things as well as to be underwater. Participants spent from 2 to 26 days in the tournament locations (median equal to 7 days), which implies a total expenditure to solely participate to the tournaments ranging from 800 to 3500 Euros (mean ± standard deviation; 1800 ± 591 euros). This study represents the first ecological, social and economic baseline knowledge for an integrative management of contemporary spearfishing tournament
Intermittency in Turbulence: computing the scaling exponents in shell models
We discuss a stochastic closure for the equation of motion satisfied by
multi-scale correlation functions in the framework of shell models of
turbulence. We give a systematic procedure to calculate the anomalous scaling
exponents of structure functions by using the exact constraints imposed by the
equation of motion. We present an explicit calculation for fifth order scaling
exponent at varying the free parameter entering in the non-linear term of the
model. The same method applied to the case of shell models for Kraichnan
passive scalar provides a connection between the concept of zero-modes and
time-dependent cascade processes.Comment: 12 pages, 5 eps figure
Coastal observatories for monitoring of fish behaviour and their responses to environmental changes
The inclusion of behavioral components in the analysis of a community can be of paramount importance in marine ecology. Diel (i.e., 24-h based), seasonal activity rhythms, or longer durational in behavioral responses can result in shifts in populations, and therefore on measurable abundances. Here, we review the value of developing cabled video observatory technology for the remote, long-term, and high-frequency monitoring of fish and their environments in coastal temperate areas. We provide details on the methodological requirements and constraints for the appropriate measurement of fish behavior over various seasonal scales (24 h, seasonal, annual) with camera systems mounted at fixed observatory locations. We highlight the importance of using marine sensors to simultaneously collect relevant environmental data in parallel to image data acquisition. Here we present multiparametric video, oceanographic, and meteorological data collected from the Mediterranean observatory platform, OBSEA (www.âobsea.âes; 20 m water depth). These data are reviewed in relation to ongoing and future developments of cabled observatory science. Two key approaches for the future improvement of cabled observatory technology are: (1) the application of Artificial Intelligence to aid in the analysis of increasingly large, complex, and highly interrelated biological and environmental data sets, and (2) the development of geographical observational networks to enable the reliable spatial analysis of observed populations over extended distances
Drop impact upon micro- and nanostructured superhydrophobic surfaces
We experimentally investigate drop impact dynamics onto different
superhydrophobic surfaces, consisting of regular polymeric micropatterns and
rough carbon nanofibers, with similar static contact angles. The main control
parameters are the Weber number \We and the roughness of the surface. At small
\We, i.e. small impact velocity, the impact evolutions are similar for both
types of substrates, exhibiting Fakir state, complete bouncing, partial
rebouncing, trapping of an air bubble, jetting, and sticky vibrating water
balls. At large \We, splashing impacts emerge forming several satellite
droplets, which are more pronounced for the multiscale rough carbon nanofiber
jungles. The results imply that the multiscale surface roughness at nanoscale
plays a minor role in the impact events for small \We \apprle 120 but an
important one for large \We \apprge 120. Finally, we find the effect of
ambient air pressure to be negligible in the explored parameter regime \We
\apprle 150Comment: 8 pages, 7 figure
Lattice Boltzmann simulations in microfluidics: probing the no-slip boundary condition in hydrophobic, rough, and surface nanobubble laden microchannels
In this contribution we review recent efforts on investigations of the effect
of (apparent) boundary slip by utilizing lattice Boltzmann simulations. We
demonstrate the applicability of the method to treat fundamental questions in
microfluidics by investigating fluid flow in hydrophobic and rough
microchannels as well as over surfaces covered by nano- or microscale gas
bubbles.Comment: 11 pages, 6 figure
Experimental SizeâSelective Harvesting Affects Behavioral Types of a Social Fish
In most fisheries, larger fish experience substantially higher mortality than smaller fish. Body
length, life-history and behavioral traits often correlate, such that fisheries-induced changes
in size or life-history can also alter behavioural traits. However, empirical evidence regarding
how size-selective harvesting alters the evolution of behavioural traits in exploited stocks is
scarce. We used experimental lines of zebrafish (Danio rerio) that were exposed to positive,
negative or random size-selective harvest over five generations. Our aim was to investigate
whether simulated fishing changed the mean personality of the surviving females five
generations after initial harvesting halted. We found that mean boldness, activity, and
sociability were significantly altered relative to a randomly harvested control line. Harvestinduced changes in individual-level personality were only detected in the negatively sizeselected line. By contrast, we did not detect harvest-induced evolution of personality in the
positively size-selected line. We conclude that size-selective harvesting alters individual fish
personality in a social fish.peerReviewe
First Assessment of the Impacts of the COVID-19 Pandemic on Global Marine Recreational Fisheries
This work is the result of an international research effort to determine the main impacts of the COVID-19 pandemic on marine recreational fishing. Changes were assessed on (1) access to fishing, derived from lockdowns and other mobility restrictions; (2) ecosystems, because of alterations in fishing intensity and human presence; (3) the blue economy, derived from alterations in the investments and expenses of the fishers; and (4) society, in relation to variations in fishersâ health and well-being. For this, a consultation with experts from 16 countries was carried out, as well as an international online survey aimed at recreational fishers, that included specific questions designed to capture fishersâ heterogeneity in relation to behavior, skills and know-how, and vital involvement. Fishersâ participation in the online survey (5,998 recreational fishers in 15 countries) was promoted through a marketing campaign. The sensitivity of the fishersâ clustering procedure, based on the captured heterogeneity, was evaluated by SIMPER analysis and by generalized linear models. Results from the expert consultation highlighted a worldwide reduction in marine recreational fishing activity. Lower human-driven pressures are expected to generate some benefits for marine ecosystems. However, experts also identified high negative impacts on the blue economy, as well as on fisher health and well-being because of the loss of recreational fishing opportunities. Most (98%) of the fishers who participated in the online survey were identified as advanced, showing a much higher degree of commitment to recreational fishing than basic fishers (2%). Advanced fishers were, in general, more pessimistic about the impacts of COVID-19, reporting higher reductions in physical activity and fish consumption, as well as poorer quality of night rest, foul mood, and raised more concerns about their health status. Controlled and safe access to marine recreational fisheries during pandemics would provide benefits to the health and well-being of people and reduce negative socioeconomic impacts, especially for vulnerable social groups.VersiĂłn del edito
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