Browsing by Author "Pousão-Ferreira, P."
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- Behavioural responses of sardines Sardina pilchardus to simulated purse-seine capture and slippingPublication . Marçalo, A.; Pousão-Ferreira, P.; Pierce, G. J.; Stratoudakis, Y.; Erzini, KarimThe behavioural effects of confinement of sardine Sardina pilchardus in a purse seine were evaluated through three laboratory experiments simulating the final stages of purse seining; the process of slipping (deliberately allowing fishes to escape) and subsequent exposure to potential predators. Effects of holding time (the time S. pilchardus were held or entangled in the simulation apparatus) and S. pilchardus density were investigated. Experiment 1 compared the effect of a mild fishing stressor (20min in the net and low S. pilchardus density) with a control (fishing not simulated) while the second and third experiments compared the mild stressor with a severe stressor (40min in the net and high S. pilchardus density). In all cases, sea bass Dicentrarchus labrax were used as potential predators. Results indicated a significant effect of crowding time and density on the survival and behaviour of slipped S. pilchardus. After simulated fishing, S. pilchardus showed significant behavioural changes including lower swimming speed, closer approaches to predators and higher nearest-neighbour distances (wider school area) than controls, regardless of stressor severity. These results suggest that, in addition to the delayed and unobserved mortality caused by factors related to fishing operations, slipped pelagic fishes can suffer behavioural impairments that may increase vulnerability to predation. Possible sub-lethal effects of behavioural impairment on fitness are discussed, with suggestions on how stock assessment might be modified to account for both unobserved mortality and sub-lethal effects, and possible approaches to provide better estimates of unobserved mortality in the field are provided. (C) 2013 The Fisheries Society of the British Isles
- Development of chondroid tissues in lordotic-kyphotic Senegalese sole (Solea senegalensis)Publication . Cardeira Da Silva, João; Mendes, A. C.; Pousão-Ferreira, P.; Cancela, Leonor; Gavaia, Paulo J.Vertebral deformities are frequent and constitute a major drawback for many aquaculture produced species. Lordosis and kyphosis, which are severe curvatures of the vertebral column, are particularly problematic, compromising fish marketing and profitability. Senegalese sole is a species with increasing interest in this industry and, like many others, presents high frequencies of vertebral deformities under rearing conditions.
- Early axial and appendicular skeletal development of the meagre (Argyrosomus regius). A comparison of two rearing systemsPublication . Valles, E.; Cardeira Da Silva, João; Dionísio, Gisela; Estévez, A.; Pousão-Ferreira, P.; Cancela, Leonor; Gavaia, Paulo J.The meagre (Argyrosomus regius) is a new species for aquaculture with high economical value, presenting growth rates of 1 kg/year. Skeletal deformities generally appear in cultured larvae at early stages, reducing the value of the fish. The present study describes the osteological development of the vertebral column and fins in meagre larvae. Meagre larvae were obtained from wild broodstocks, kept at IRTA and IPIMAR, and induced to spawn using GnRHa injection.
- Early osteological development and deformities of Diplodus sargus (Linnaeus, 1758) and Diplodus vulgaris (Saint-Hillaire, 1817)Publication . Gavaia, Paulo J.; Nicolau, L.; Cancela, Leonor; Pousão-Ferreira, P.Despite the low incidence of morpho-anatomical abnormalities occurring in natural populations, this pose a serious problem for cultivated fish causing increased mortality, reduced growth and conversion rates, thus limiting production and profits. In this study we made an osteological evaluation in the white seabream (Diplodus sargus) and in the common two-banded seabream (Diplodus vulgaris), two sparid species currently under adaptation to intensive aquaculture.
- Early skeletal development of meagre (Argyrosomus regius, Asso 1801)Publication . Cardeira Da Silva, João; Nicolau, L.; Pousão-Ferreira, P.; Cancela, Leonor; Gavaia, Paulo J.The meagre (Argyrosomus regius) is a marine teleost with high growth rates and excellent biological characteristics for rearing, making it a proper candidate for diversification of aquaculture in Southern Europe. The description of skeletal development is essential to establish chronometric relationships between skeletal developments, types of ossification, processes and different development stages, contributing to the improvement of rearing conditions.
- Effect of simulated purse seine fishing on acclimated sardines and post-fishing interactions with predatorsPublication . Marçalo, A.; Araújo, J.; Pousão-Ferreira, P.; Erzini, Karim; Stratoudakis, Y.The fate of fish deliberately released (slipped) during purse seining is poorly studied and estimating unaccounted mortality rates in pelagic fisheries has been difficult and imprecise.
- Evaluation of the skeletal quality in Senegalese sole (Solea Senegalensis, Kaup) reared under intensive vs extensive conditionsPublication . Gavaia, Paulo J.; Richard, Nadège; Dâmaso, L.; Dinis, Maria Teresa; Pousão-Ferreira, P.; Engrola, S.; Conceição, L. E. C.; Cancela, Leonor- Senegalese sole is distributed along the Mediterranean and southwestern Europe, reaching a market price of 20-25 €/kg - Promising species for aquaculture diversification - Control and intensification of culture is reasonably achieved - The high incidence of skeletal anomalies in intensively reared fish represents a constraint to commercial production - Samples from Portugal and Greece were analyzed towards identifying skeletal differences due to rearing conditions
- Fish larvae quality descriptors: an appraisal of methods for red porgy Pagrus pagrus and grouper Epinephelus marginatus produced under different rearing conditionsPublication . Andrade, Carlos A. P.; Nogueira, N.; Silva, Paula; Cordeiro, Nereida; Cunha, M. E.; Pousão-Ferreira, P.; Ribeira, Laura; Bandarra, N.; Gavaia, Paulo J.Quality control in fish hatcheries is of paramount importance to achieve the desired characteristics of larvae and fry, either for the market or release to the wild. Quality programmes are applied in a day to day basis having direct implications for production management and final costs of product. Most common criteria used for larval quality assessment are morphometrics, condition factor, histometrical indices, lipid analysis, nucleic acid ratios, enzyme activity and stress tests.
- Fishing simulation experiments for predicting the effects of purse-seine capture on sardine (Sardina pilchardus)Publication . Marçalo, Ana; Araújo, João; Pousão-Ferreira, P.; Erzini, Karim; Stratoudakis, YorgosTo study the impact of purse-seine fishing on deliberately released sardine, two laboratory experiments were performed to explore the effect of net confinement for 10, 20, 40, and 60 min at 18 and 238 degrees C. A third experiment considered two levels of fish density while confined for 20 and 40 min at 16 degrees C. Analysis of cortisol and haematocrit demonstrated that stress immediately after simulated fishing was milder than in commercial fishing and did not correlate with observed delayed mortality. Scale loss was related to the probability of dying (mean values of 16.3 and 2% for dead fish and survivors, respectively), and fin erosion was a long-term stress response observed in both dead and surviving fish. Time of confinement was an important stressor, with survival rates decreasing significantly with increasing periods in the net, and temperature having an additional negative effect. Density effects were less conclusive, but there was some indication that survival correlated with biological condition (heavier fish were more likely to survive). It seems that delayed mortality after release can be substantial, although death is not certain and appropriately modified fishing operations and favourable environmental conditions may enhance the probability of sardine survival.
- Hormonal induction of Atlantic dusky grouper (Epinephelus marginatus) broodstockPublication . Conceição, L. E. C.; Cabrita, Elsa; Engrola, S.; Lacuisse, M.; Pousão-Ferreira, P.; Dinis, Maria TeresaImmature fish and young females were sex reversed using hormonal induction in two consecutive years. In the first year one permanent male was obtained. Collected sperm of both years ranges from 30 μl to 300 μl and cell concentration varies from 3 to 6.5 x109 spermatozoa/ml. Atlantic dusky grouper can successfully be induced to functional males with 17α-methyltestosterone implants.
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