26 research outputs found
Survival rates and physiological recovery responses in the lesser-spotted catshark (Scyliorhinus canicula) after bottom-trawling, Comparative Biochemistry and Physiology, Part A
In 2019, Europe will adopt a no-discards policy in fisheries. This entails the landing of captured species unless
strong evidence is provided supporting their survival and recovery after fishing. Thus, research on this topic is
gaining momentum. Bottom-trawling, as a non-selective fishing method, is characterized by a high proportion of
discards including vulnerable key species, such as demersal sharks. Their survival may also depend on capture
depth. By paralleling onboard and laboratory experiments with the small-spotted catshark, Scyliorhinus canicula,
we offer a robust experimental design to assess the survival of discarded sharks. Catsharks were captured by
bottom-trawling at two depths (shallow ~89 m and deep ~479 m). Blood samples were collected following trawl
capture and analyzed for stress biomarkers (lactate, osmolality, phosphate, urea). During recovery in onboard
tanks, behavior was video-recorded and fish were re-sampled after 24 h. A second experiment was conducted in
laboratory facilities to simulate air-exposure after trawling and to analyze the physiological recovery. Our results
showed that 95.7% of the animals survived 24 h after trawling. We confirmed that trawling elicited acute stress
responses in catshark but that they managed to recover. This was demonstrated by lactate concentrations that
were 2.6 mM upon capture, but recovered to assumed baselines after 24 h (0.2 mM). Non-invasive video monitoring revealed behavioral differences with depth, whereby those captured at 89 m depth required longer to
recover than those captured at 479 m depth. Implementation of standardized survival studies by fishery managers can benefit from holistic physiological approaches, such as the one proposed her
Oleinas como materias primas de estólidos para aplicaciones como biolubricantes
4 pages, 4 tables.[EN] This study deals with the synthesis of estolides from
high-oleic sunflower oil oleins, and its potential use as
viscosity modifiers for biolubricant applications. Synthesis
reactions were monitored for 24 h. Estolide molecular
weight increased continuously with reaction time. Dynamic
viscosities and densities of the different estolides were
measured in a temperature range comprised between 10 and
120 °C. Maximum viscosities and estolide molecular weight
were obtained after 12 h of reaction. However, the largest
viscosity increments were observed within the first 3 hours
of processing, due to a dramatic increase in the molecular
weight of the estolides.[ES] En este estudio se presenta la síntesis de estólidos a
partir de oleinas de girasol alto-oleico y su utilización potencial
como modificadores de la viscosidad en aplicaciones como
biolubricantes. La reacción de síntesis se controló durante
24h. El peso molecular de los estólidos se incrementa
durante todo el periodo de reacción. Las viscosidades dinámicas
y densidades de los diferentes estólidos se midieron
en un rango de temperatura entre 10 y 120 °C. El máximo de
viscosidad y de peso molecular se alcanza al cabo de 12 horas
de reacción, sin embargo, el incremento mayor de viscosidad
se produce durante las 3 primeras horas de tratamiento
debido al importante aumento del peso molecular del
estólido.This work was
supported by research grants from MCYT (PSE-
320100-2006) and FEDER.Peer reviewe
Physiological recovery after bottom trawling as a method to manage discards: The case study of Nephrops norvegicus and Squilla mantis.
The European Fisheries Policy aims at a progressive elimination of discards. An exception from this regulation includes the release of species with high survival rates
after capture. In south-western Atlantic waters of Europe, Norway lobster (Nephrops norvegicus) and spottail mantis shrimp (Squilla mantis) are amongst the most
important crustacean species captured by bottom trawling. We evaluated their short-term survival probability, survival rates and recovery capacities after being
trawled by an oceanographic vessel. Seasonal differences were considered by sampling in spring and autumn. In order to characterise the full recovery after capture,
physiological responses were also analysed along a time-course of 24 h. Our results confirm that bottom trawling is a stressful process to these crustacean species, as
seen by changes in plasma and muscle metabolites, hemocyanin and immune system parameters. However, maintaining captured animals in onboard water tanks
evidenced the full physiological recovery of survivors after 6 h and before 24 h. Survival in Norway lobster and spottail mantis shrimp varied according to the season,
being higher in spring (68.4 � 7.1% and 87.0 � 4.7%, respectively) than in autumn (33.8 � 7.8% and 63.8 � 9.3%, respectively), probably due to the higher
temperatures registered after summer months. The employment of the presented techniques for the evaluation of other crustaceans, fishing gears and geographical
areas can be contemplated. Fisheries stakeholders might use this approach to better manage discards in Europ