Parisi, V.; Manjabacas, A.; Lombarte, A.; Olivella, R.; Chic, O.; Piera, J.; Garcia, E. Fisheries research Vol. 105, num. 1, p. 13-20 DOI: 10.1016/j.fishres.2010.02.005 Data de publicació: 2010-06 Article en revista
Automated Taxon Identification (ATI) systems that use a database to identify species or anatomical structures
of species from different taxonomical groups have recently been developed. However, few of these
works have been applied to marine organisms. In this paper we develop an ATI system for identifying
Actynopterigian species from their otolith contour; this is important information for the palaeontological,
ictiological and ecological sciences, especially in food web studies. The AFORO website comprises the first
web-based automated species identification system based exclusively on otolith shape outline. Species
are identified iteratively based on a multiscale representation of the otolith contour. The ATI system is
very easy to use as it only requires uploading a suitably oriented otolith image on a black background.
Two tests were carried out with a database of 1480 images of left sacullar otoliths (sagittae) from 420
species. The first test analysed 50 different otoliths, 10 per species, from 5 different species. The second
test identified 50 otoliths, each from a different species. The two tests obtained similar results (percentage
of correct identifications): 72% of specimens were correctly identified at species level, and the percentage
increased to 90% at genus level and reached 94% at family level. The best results are obtained for species
which have an otolith contour with a very specific morphology, such as the mackerel Scomber colias, and
the less efficient results for species with common shaped otoliths with unclear specific characteristics,
such as the Mediterranean horse-mackerel Trachurus mediterraneus, or species with large morphological
variability between individuals, such as Lophius budegassa or Synodus saurus.
Sala, A.; Prat, J.; Prat-Farran,J.A. ; Prat, J.A.; Antonijuan, J.; Lucchetti, A. Fisheries research Vol. 100, num. 2, p. 156-166 DOI: 10.1016/j.fishres.2009.07.004 Data de publicació: 2009-10 Article en revista
A new door has been designed to reduce hydrodynamic drag coefficient and increase spread of door
commonly used in the Mediterranean commercial demersal trawl fisheries. Flume tank testing and engineering
sea trials provide data which allow us to illustrate the performance and impact on the seabed of
an existing door and a new door design. In the flume tank, each model was tested over a range of attack
angles and for a limited range of otterboard heels. Curves of spreading-, drag- and down-force coefficients
have been calculated. In the case of sea trials in order to extract the hydrodynamic coefficients an
analysis has been applied and a mathematical model was used to calculate attack angle functions. From
analysing the differences between engineering sea trials and flume tank tests we have deduced some
conclusions about additional ground contact forces on sea trials that affect the performance of the doors.
Moreover, a comparison between reaction forces of the flume tank and the estimation of reaction forces
at sea has been given. Finally, this study allowed us to notice important differences between traditional
and experimental otterboards.
Prat, J.; Prat-Farran,J.A. ; Prat, J.A.; Antonijuan, J.; Folch, A.; Sala, A.; Lucchetti, A.; Sardà, F.; Manuel, A. Fisheries research Vol. 94, num. 1, p. 109-117 DOI: 10.1016/j.fishres.2008.07.007 Data de publicació: 2008-10 Article en revista