Serra-Pereira B.,Institute Investigacao das Pescas e do Mar |
Figueiredo I.,Institute Investigacao das Pescas e do Mar
Marine and Coastal Fisheries | Year: 2011
There is a need for a unified terminology to describe reproductive phase assignment across fish taxa, regardless of the reproductive strategy involved. Reproductive terminology already adopted for teleosts has been applied to oviparous elasmobranchs of both sexes. A historical review of the terminologies used by previous authors and how these correspond to the new terminology is presented. Five reproductive phases are considered: immature, developing, spawning capable (which includes an actively spawning subphase), regressing, and regenerating. By using an oviparous elasmobranch, the thornback ray Raja clavata, as an example, the different phases are described based on both macroscopic and microscopic features of the reproductive tract, including the ovaries, oviducal glands, and uterus in females and the testes, claspers, and sperm ducts in males. The regressing phase was observed in females, but the regenerating phase was not; neither of these two phases was observed in males. Records from other species suggest that all five reproductive phases can be found in oviparous elasmobranchs, depending on the reproductive strategy of the species. © American Fisheries Society 2011.
Custodio P.J.,University of Lisbon |
Pessanha S.,University of Lisbon |
Pereira C.,Institute Investigacao das Pescas e do Mar |
Carvalho M.L.,University of Lisbon |
Nunes M.L.,Institute Investigacao das Pescas e do Mar
Food Chemistry | Year: 2011
The purpose of this work is to compare the elemental content of samples of wild and farmed fish from four different Portuguese locations.Samples of Gilthead Bream and Sea Bass were gathered at fish farms and docks of four of the most important Portuguese harbours. These species were chosen because they are very important from both the economic and consumers points of view.In order to obtain the elemental content of the essential and toxic elements present in the samples, two elemental techniques were used EDXRF and FAAS. No significant differences were found in what concerns the essential elements. Regarding toxic elements, higher concentrations of Cd, Hg and Pb were systematically found between the samples of a given fish farming industry and the fish caught in the sea in the same region. Despite these differences, no values above the recommended regulations were found. © 2010.
Wise L.,Institute Investigacao das Pescas e do Mar |
Murta A.G.,Institute Investigacao das Pescas e do Mar |
Carvalho J.P.,INESC ID |
Carvalho J.P.,University of Lisbon |
Mesquita M.,Instituto Superior Of Agronomia Utl And Cio Fcul
Ecological Modelling | Year: 2012
As managers and fishery scientists become increasingly aware of the need to understand fishermens' behaviour when faced with new management strategies, there is a growing need to develop models that describe their decision-making processes and tools that are able to simulate the possible outcomes of alternative management scenarios. This paper shows how data collected on board fishing vessels, a source of data currently available for many fleets and fisheries around the world, can be combined with Rule Based Fuzzy Cognitive Maps, a modelling technique that is able to deal with both quantitative and qualitative data. Results show that the presented model is able to replicate with a reasonably precision the behaviour of a pelagic fishery. Results and the potential of Rule-Based Fuzzy Cognitive Maps to predict fisher's behaviour are discussed. © 2011 Elsevier B.V.
Castro N.,University of Lisbon |
Castro N.,Institute Investigacao das Pescas e Do Mar |
Costa J.L.,University of Lisbon |
Domingos I.,University of Lisbon |
Angelico M.M.,Institute Investigacao das Pescas e Do Mar
Journal of the Marine Biological Association of the United Kingdom | Year: 2013
The diets and trophic ecology of the dominant fish species from the marine coastal region of Aveiro (north-western Portugal) caught during a summer survey were studied. Mysids were the most important prey group for the fish assemblage analysed. As a consequence, there was a high dietary overlap between species and a low incidence of piscivory. Nevertheless, a clear segregation of trophic niches was observed, with one group (comprising the species Chelidonichthys cuculus, Callionymus lyra, Dicologlossa cuneata and Pomatoschistus lozanoi) showing a stronger preference for infaunal epibenthic prey, such as polychaetes and amphipods, another group (including Arnoglossus imperialis, Arnoglossus laterna, Chelidonichthys obscurus, Chelidonichthys lucernus, Echiichthys vipera, Pagellus acarne and Trisopterus luscus) preying mostly upon suprabenthic prey, mainly mysids, and a third group (Engraulis encrasicolus and Trachurus trachurus) feeding largely on planktonic prey like copepods. Some species, including A. imperialis, C. lyra, E. vipera, T. trachurus and T. luscus, showed ontogenic diet shifts that may be related to the habitat occupied by different size-classes and/or to their ability to capture prey of different size. © 2012 Marine Biological Association of the United Kingdom.
Almeida C.,Institute Investigacao das Pescas e do Mar |
Soares F.,Institute Investigacao das Pescas e do Mar
Marine Pollution Bulletin | Year: 2012
The microbiological pollution of coastal waters is a major problem, especially in shellfish areas. This article shows the faecal contamination in bivalves from the Ria Formosa Lagoon (south coast of Portugal) along 20. years (1990-2009). The highest values of Escherichia coli in bivalves were obtained during the 90s, related with the discharge of untreated wastewaters and agricultural runoff. In the 2000s contamination levels decreased, with 83% of the population already served by new or remodelled sewage treatment plants. The highest levels were found in bivalves close to the largest city, where punctual and diffuse contamination sources still exist. Bivalves from the less impacted site showed the lowest contamination, an area with more water renewal. Seasonally, the highest levels were in autumn and winter, due to the runoff of waters from rainfall. These were opposite to those in spring and summer, when the highest temperatures and salinity showed a bactericidal effect. © 2011 Elsevier Ltd.
Goncalves P.,Institute Investigacao das Pescas e do Mar |
Henriques E.,Institute Investigacao das Pescas e do Mar |
Angelico M.M.,Institute Investigacao das Pescas e do Mar
Fisheries Research | Year: 2013
Fish egg identification is relevant for a variety of ecological studies including the application of egg production methodologies to estimate population abundance. The Daily Egg Production Method (DEPM) has been applied triennially, since 2007, for horse mackerel (Trachurus trachurus) in Iberian waters. In this region a less abundant species of the same genus co-occurs, blue jack mackerel (T. picturatus), but up to now little is known on its spawning seasonality. At present, horse mackerel egg identification in plankton samples is done based on morphological characteristics. Eventual egg misidentification may lead to inaccurate estimates of stock biomass. During the 2010 DEPM survey, spawning blue jack mackerel were caught together with horse mackerel in the same fishing haul. Artificial fertilization was undertaken for both species and egg development followed. Embryogenesis was divided into eleven stages and the morphological features were compared for the two species. The rates of development were assessed using a multinomial modelling approach. The experiments showed that eggs of T. picturatus are very similar in appearance to those of T. trachurus but the former are slightly but significantly larger (chorion and oil globule diameters). Considerable overlap exists among the egg characteristics of the two species indicating that morphological separation of eggs of these species are problematic. Egg development for T. trachurus was faster than for T. picturatus. Entire egg development until hatching occurred in 67. h for T. trachurus while T. picturatus needed an extra 8. h at a water temperate of 16.5 °C. © 2012 Elsevier B.V.