resultados
Descubrir
Envíos recientes
Item type: Ítem , Access status: Acceso Abierto , Growth parameters and mortality rate of the Scomber japonicus peruanus (Jordán & Hubb, 1925) along the Peruvian coast, South Pacific(Universidade de Sao Paulo, 2008) Caramantin-Soriano, Hilda; Vega-Pérez, Luz Amelia; Ñiquen Carranza, MiguelThe growth parameters and the mortality rates of the Scomber japonicus peruanus (Chub mackerel) were studied based on monthly data of frequency of fork length classes obtained from commercial landings off the Peruvian coast from 1996 to 1998. The asymptotic body length and growth rate values obtained by the ELEFAN I (Electronic Length Frequency Analysis) ranged from 40.20 cm to 42.20 cm and from 0.38 to 0.39, respectively. The oscillation amplitude was 0.60; the Winter point values varied from 0.50 to 0.60 and the performance index from 2.79 to 2.84. The total mortality rate of the Chub mackerel obtained by the linearized catch curve oscillated between 1.68 and 3.35. The rate of fishing mortality varied from 1.16 to 2.78 and the exploitation rate from 0.68 to 0.84. The annual rate of natural mortality estimated by the Pauly’s method ranged from 0.52 to 0.53. The results obtained allow us to conclude that the longevity of the Chub mackerel was slightly over seven years.Item type: Ítem , Access status: Acceso Abierto , Schooling behaviour of small pelagic fish: phenotypic expression of independent stimuli(Inter-Reseach Science Publiser, 2007) Brehmer, Patrice; Gerlotto, Francois; Laurent, Charline; Cotel, Pascal; Achury, Alina; Samb, BiraneWe compared echo sounder measurements of fish schools on Venezuelan and Senegalese coastal shelves. In both areas Sardinella aurita was the predominant aggregative species; the stocks are known to be genetically independent. Persistent school typology is described by analysing 7 acoustic surveys in Venezuela and comparing with pioneer observations in Senegal. The echo types encountered in both countries were comparable, with S. aurita and their associated species having comparable schooling behaviour. School morphology appears to be more related to species than to global characteristics of their ecosystems, as fish school descriptors were similar for both stocks. Nevertheless, S. aurita may adopt different school morphologies. Differentiation between day and night fish schools was mainly due to morphological variables, as determined by fractal dimension. Echo types were different between day and night in both Venezuela and Senegal. This analysis shows that several independent parameters can influence school morphology. However, although schooling behaviour is temporally highly variable, it shows several constant, typical 2D morphological structures, i.e. echo types. The observation of small pelagic fish schools occurring during the night is not unusual according to the literature, although a strict diurnal schooling behaviour, with scattering during the night, is often reported. Schooling behaviour appears to be a phenotypic expression depending on biotic and abiotic stimuli, intrinsic characteristics and motivation.Item type: Ítem , Access status: Acceso Abierto , On differences in satellite wind products and their effects in estimating coastal upwelling processes in the south-east Pacific(American Geophysical Union (AGU), 2006) Croquette, Marie; Eldin, Gérard; Grados Quispe, Carmen; Tamayo, MyrianAlongshore wind stress and curl obtained from ERS and QuikSCAT satellite wind products are routinely used to investigate coastal upwelling dynamics in the south-east Pacific. North of 17°S and south of 26°S there is a good agreement in the seasonal cycle of both products. Data from Peruvian coastal wind stations are used to validate satellite coastal winds. Between 17°S and 26°S seasonal cycles from coastal stations are in phase with QuikSCAT but in opposition with ERS. This discrepancy is confirmed during the overlapping period of the satellite products. Therefore, data from ERS do not seem to capture the strong cross-shore wind gradient in that area, while QuikSCAT renders at least part of it. These differences are dramatically enhanced when computing the wind stress curl along the coast: estimates of Ekman pumping obtained from QuikSCAT data in a coastal band are 2–3 times higher than those achieved with ERS data.Item type: Ítem , Access status: Acceso Abierto , Boletín Diario Oceanográfico vol. 13 N° 224, 2026(Instituto del Mar del Perú, 2026-08-12) Instituto del Mar del Perú. Dirección General de Investigaciones Oceanográficas y Cambio ClimáticoCon un máximo de +7,31 °C frente a Chicama, este sector se consolida como el núcleo de mayor intensidad, dentro de un escenario costero con promedio de +3,79 °CItem type: Ítem , Access status: Acceso Abierto , Diseases, lesions and malformations in the long-beaked common dolphin Delphinus capensis from the Southeast Pacific(Inter-Research Science Publisher, 2006) Bressem, Marie-Françoise Van; Waerebeek, Koen Van; Montes, David; Kennedy, Seamus; Reyes, Julio C.; Garcia-Godos, Ignacio A.; Onton-Silva, Karina; Alfaro-Shigueto, JoannaMiscellaneous lesions of the head, skull, teeth, trunk, appendages, skin and genital tract were observed in 120 of 930 long-beaked common dolphins Delphinus capensis taken in fisheries off Peru between 1985 and 2000. Seven subsamples were defined according to the varying field sampling protocols. Forty-two dolphins showed at least 2 types of injuries or diseases affecting 1 or more organs. The majority (5 of 7) of traumas encountered were diagnosed as caused by violent, fisheriesrelated interactions, and the skin in 20.4% of specimens (n = 54) showed healed scars from such interactions. Prevalences of malformations and traumas of crania (n = 103) were 2.9 and 1.9%, respectively. Lytic cranial lesions were present in 31.1% of dolphins (n = 103) and accounted for 84.2% of all bone injuries. Skull damage diagnostic for Crassicauda sp. infestation was encountered in 26.5% of dolphins (n = 98) and did not differ among sex and age classes. Crassicauda sp. and tooth infections were responsible for, respectively, 78.8 and 6.1% of the lytic lesions. Adult dolphins showed a high prevalence of worn and broken teeth (35%, n = 20) as well as damaged alveoli (20%, n = 70). Prevalence of ‘paired teeth’, a congenital condition, was 9.4% (n = 32). Lesions of the head, body and appendages were present in 10 dolphins and included traumas, deformations (e.g. scoliokyphosis and brachygnathia) and chronic mastitis. Ovarian cysts suggestive of follicular cysts were observed in 1 of 24 females. Chronic orchitis affected 1 of 78 males. Of 12 dolphins 2 had vesicular lesions of the penis. Prevalence of cutaneous lesions, abnormalities and scars ranged between 1.8% (n = 56) and 48.2% (n = 27).
