452 research outputs found
Do pingers cause stress in fish? An experimental tank study with European sardine, Sardina pilchardus (Walbaum, 1792) (Actinopterygii, Clupeidae), exposed to a 70 kHz dolphin pinger
Date of acceptance: 06/12/2014 Acknowledgments The study was funded by the Portuguese Ministry of Science (Fundac¸a˜o para a Cieˆncia e Tecnologia– FCT) through a PhD Grant of SG (SFRH/BD/47931/2008). We would like to thank the captain of the purse-seiner (Jose´ Manuel Saveedra) and his crew for facilitating the capture and transport of live fish. Moreover, we want to thank Ana Marcalo for suggestions on the experimental design, Manuel Garci for technical advice on underwater video recordings and James Turner from the company Future Oceans for providing technical details on the 70 kHz dolphin pingers. We would also like to acknowledge the scientific advice of Dr. Jose Iglesias and the technical and logistic support for the preparation of the laboratory and the materials for tank experiments by Enrique Martınez Gonzalez, Ricardo Pazo and other staff at the aquaculture facilities of the Spanish Institute for Oceanography (IEO) and the Marine Sciences Station of Toralla (ECIMAT) in Vigo. Furthermore, we are grateful to Francisco de la Granda Grandoso for his practical assistance during the fish tank experiments and to Juan Santos Blanco for helping with statistical analysis. Finally, we would like to thank Pilar Riobo Agula, Amelia Fernandez Villamarin, Jose Franco Soler, Jose Luis Munoz, Angela Benedetti, Marcos Antonio Lopez Patio and Marta Conde Sieira for scientific advice and practical support with cortisol analysis and Rosana Rodrıguez for preparing histological samples for us.Peer reviewe
Eledone cirrhosa and SPICT or why it is not easy to assess a short lived cephalopod species
Poster.-- Iberian Symposium on Modeling and Assessment of Fishery Resources, 19-22 October, Vigo, SpainAlthough some cephalopods have had always commercial value and others started to increase in value in recent years, unlike European Atlantic stocks of many commercially important finfish and crustaceans, they are not routinely assessed and no specific management measures are applied to fleets catching cephalopods, with the exception of some regional harvest control rules for artisanal fleets. Among the species that has been gaining importance in landings is the horned octopus Eledone cirrhosa. This octopus represents an important bycatch for several North Spanish otter trawl fisheries, appearing in landings but also in discards. Like other cephalopods, E. cirrhosa is a short-lived and fast growing species, and previous studies showed that its abundance varies in relation to physical and environmental conditions.
As a first step towards its possible future inclusion in the ICES annual assessment system, a simple assessment model has been tested in the ICES Working Group on Cephalopod Fisheries and Life History (WGCEPH). The chosen model was SPICT (Surplus Production model in Continuous Time). Using landings and two abundance indices (from a commercial fleet and a scientific bottom trawl survey), preliminary results have been obtained. Overall, although the model converged and all the diagnostics were acceptable, the estimated parameters obtained very wide confidence intervals, suggesting that improvements in the model are needed. Further work, including testing other assessment models or selecting other tuning indices, will help in the assessment process for this speciesN
Effect of initiating drug treatment on the risk of drug-related poisoning death and acquisitive crime among offending heroin users.
BACKGROUND: A recent Cochrane review of randomised trials identified a lack of evidence for interventions provided to drug-using offenders. We use routine data to address whether contact with treatment services reduces heroin users' likelihood of a future acquisitive offence or drug-related poisoning (DRP) death. METHODS: Heroin-users were identified from probation assessments and linked to drug-treatment, mortality and offending records. The study cohort was selected to ensure that the subject was not: in prison, in treatment or had recently left treatment. Subjects were classed as initiators if they attended a triage appointment within two weeks of their assessment; non-initiators otherwise. Initiator and non-initiators were compared over a maximum of one year, with respect to their risk of recorded acquisitive offence or DRP-death. Balance was sought using propensity score matching and missing data were accounted for using multiple imputation. RESULTS: Nine percent of assessments identified for analysis were classed as initiators. Accounting for observed confounding and missing data, there was a reduction in DRPs associated with initiator assessments, however there was uncertainty around this estimate such that a null-effect could not be ruled out (HR: 0.42, 95% CI 0.17-1.04). There was no evidence of a decrease in the recidivism risk, in fact the analysis showed a small increase (HR: 1.10, 95% CI 1.02-1.18). CONCLUSION: For heroin-using offenders, initial contact with treatment services does not appear to reduce the likelihood of a future acquisitive offence
Trends in the pattern of discarding in the hake (Merluccius hubbsi and Merluccius australis) fishery in the SW Atlantic.
This paper presents results from the EC Study Project 99/016 “Data collection for stock
assessment of two hakes (Merluccius hubbsi and M. australis) in international and Falkland
waters of the SW Atlantic”. Historical fishery and biological data series available from IEO
(1988 onwards) were used to describe and quantify patterns and spatio-temporal changes in catches and discards in the hake fishery. Data were collected by scientific observers on board Spanish fishing vessels operating in the study area. Data collected on fishing activity included effort, catches and discards of target and non-target species on a haul-by-haul basis. Biological information (size, sex, maturity, etc) on target species was recorded on a daily basis, while
biological data on non-target species was recorded periodically. The “discards ratio” was
calculated by each haul, defined as the total weight of fish discarded divided by the total catch weight. The most important by-catch species are hoki or whiptailed hake (Macruronus magellanicus), red cod (Salilota australis), southern blue whiting (Micromesistius australis),
Patagonian toothfish (Dissostichus eleginoides) and kingclip (Genypterus blacodes).
Discards included both target and non-target species. The most commonly discarded species were Patagonotothen spp. (almost 100% of the catch is discarded), whiptailed hake (Macruronus magellanicus) (25% discarded), southern blue whiting (12%) and red cod (6%).
These percentages vary with area, year and fishing season. The four target species (Merluccius hubbsi, Merluccius australis, Illex argentinus and Loligo gahi) have discard ratios below 5%. In recent years discard ratios for all species except Patagonotothen spp. have fallen below 15%
The trophic relationships of several commercial finfish species from the southwest Atlantic.
This study aims to quantify the trophic relationships of seven commercially valuable
predatory fish species (Argentine hake Merluccius hubbsi, southern hake Merluccius
australis, Patagonian toothfish Dissostichus eleginoides, southern blue whiting
Micromesistius australis australis, red cod Salilota australis, kingclip Genypterus blacodes and hoki Macruronus magellanicus) over a two-year period. A total of 1590 stomachs from these species was collected from the high seas of the southwest Atlantic and in the waters around the Falkland Islands. The percentage similarity index shows that all species except southern hake occupy very similar trophic positions, with a high percentage dietary overlap.
Despite this, niche breadths were relatively narrow, with the majority of feeding occurring on locally abundant prey items (notothiniid fish and the squids Illex argentinus and Loligo
gahi). In the two species for which sample size was largest, Argentine hake and kingclip,
geographical differences in diet were found, which may be related to regional variation in
prey abundance. The results are discussed in relation to the seasonal migrations of predators and prey and the hydroclimate regime
The spatio-temporal pattern of hake (M. hubbsi) abundance and environmental influence in the Patagonian shelf area
The Argentine hake (Merluccius hubbsi) is one of the most important fishery resources in the Southwest Atlantic. This species is widely distributed in the Patagonian shelf area and it is a major target species by international fleets in this South West Atlantic area. This paper presents results on the spatio-temporal distribution pattern of hake M. hubbsi abundance and environmental influence
in the Patagonian shelf area. Spanish commercial fisheries data from 1989 to 1999 were used in the analysis. Data were collected by observers deployed by the IEO, Vigo (Instituto Español de Oceanografía, Vigo). The data include 15343 fishing haul records. CPUE (Catch Per Unit Effort,
kg⋅hr-1) was used as an abundance index. The analyses of the general spatio-temporal pattern of fish abundance, and the influence of environmental factors, such as SST, SBT, depth, moon phase and cloud cover, on fish abundance and distribution, were based on correlation, variograms, and timeseries
maps created using GIS. Hake-targeted fishing by Spanish fleets was mainly focused on the shelf-edge area between 44.5°S – 47.0°S outside the Argentinean EEZ and in the area northwest of the Falkland Islands. The centre of high abundance is located in the shelf-edge area between 44.5°S – 47.0°S, particularly in the west part (i.e. in shallower waters) and in winter. The correlations between fish abundance and cloud cover are overwhelming negative, indicating that higher catches usually occur in cloudy weather conditions. In the major hake-targeted fishing area between 44.5°S – 47.0°S, the negative relationship between fish abundance and sea surface temperature in most months may suggest that high fish abundance is related to the strong northward cold Falklands current, and abundance is positively related to sea depth in summer
Fisheries interactions of Delphinus delphis in the north-east Atlantic with an emphasis on Galicia, north-west Spain.
Bycatch from interactions with fisherie
s remains the biggest global threat to marine
mammals. Galicia, north
-
west Spain, is one of the world’s main fishing regions and a high
level of cetacean
-
fisheries interactions has been reported from on
-
board observers, interviews
with fisheries stakeholde
rs and analysis of stranded and by
-
caught carcasses.
Delphinus
delphis
is the most abundant cetacean in the area and since 1990 necropsies of over 1800
stranded and by
-
caught
Delphinus
have been conducted. Life history data (age, maturity, and
pregnancy ra
te data) from stranded and by
-
caught cetaceans can be used to construct life
tables and to estimate overall mortality and fisheries mortality rates. Age and maturity were
determined from stranded and by
-
caught
Delphinus
between 1990 and 2009. Males and
fem
ales reach sexual maturity at 8.5 and 7.5 years of age, respectively, and no temporal
difference in age at sexual maturity was observed. Results indicate 13% annual mortality in
the
Delphinus delphis
north
-
east Atlantic population and necropsy data suggest
s that 60% of
mortality (i.e. 7.2% annual mortality) is attributable to fisheries interactions, predominantly
from pair trawls and gillnets. By
-
caught
Delphinus
were found to die significantly younger
than non
-
by
-
caught animals (p=<0.001) although no sex
-
r
elated difference in bycatch rate
was observed (p=0.051). The estimated annual mortality due to fisheries interactions greatly
exceeds the 2% limit set by ASCOBANS and the IWC and high bycatch rates are also
reported for other countries e.g. the UK, France
and Portugal. Although
Delphinus delphis
in
the north
-
east Atlantic is one continuous population, the high level of bycatch occurring in
parts of the range is most likely unsustainable and will be discussed. There is a need to carry
out on
-
board monitorin
g, notably in the north
-
west Iberian Peninsula (Galicia and Portugal),
to incorporate cetacean bycatch into fisheries advice and, above all, to start introducing
mitigation measures
Are there climatic signals in fishery data for sardine (Sardina pilchardus) along the Iberian Atlantic coast?
The Iberian sardine (Sardina pilchardus) is distributed along the whole shelf of the Iberian Peninsula with the highest catches being taken from southern Galician waters and northern Portugal. The fishery is dependent on the strength of the recruitment in this area and recruitment processes seem to be driven by a combination of oceanographic (local) and climatic (global) events. In an exploratory analysis we examined whether the variability observed in landings from ICES areas VIIIc (northern) and IXa (western Iberia) from 1940 to 2005, and in estimated annual recruitment and spawning stock size for the whole stock could be related to environmental conditions at large and local scales, taking into account temporal autocorrelation in the response variables. Landings for areas VIIIc and IXa show differing trends and were most strongly related, respectively, to the multi-decadal Atlantic oscillation (AMO) and to SST (with an optimum around 15o C). Recruitment was negatively related to air temperature (AT). We stress the need for taking into account time lagged effects, non linear relationships, autocorrelation in response variables and collinearity between explanatory variables. We discuss possible mechanisms underlying these observed patterns and whether the apparent climatic relationships have any predictive value
Morphometric and meristic variation in Argentine hake (Merluccius hubbsi) and southern hake (Merluccius australis) from the southwest Atlantic.
Samples of Merluccius hubbsi (N=147) were collected from the southwest Atlantic, in the high seas at 42o S and 46oS and from the waters around the Falkland Islands. A sample of M. australis (N=23) was also collected in Falkland Islands waters. Variation in the population structure was investigated using multivariate analysis of a total of external and skeletal morphometric data, counts of fin rays and teeth, and measurements on scales. All measurements were standardised to mean body size and each character set was analysed separately. Principle components analysis and discriminant analysis were used to identify differences between M. hubbsi from different areas and differences between the two species. The results indicate the presence of two groups of Merluccius hubbsi within the study area, one found on the high seas and one in the waters around the Falkland Islands. Results are discussed in relation to the reproductive and trophic migrations of M. hubbsi, the relative importance of genetic and environmental differences, and the results of similar studies from the southwest Atlantic
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