Seguiment del reclutament d'angula a l'estuari del riu Ter

Abstract

Were studied the pattern of recruitment of glass eels (Anguilla anguilla) in the estuary of the Ter River, from January 2014 until March 2015. Every fifteen days (coinciding with the phases of full moon and new moon) and during three hours after sunset experimental fishing were performed at two points of the final stretch of the Ter River, in the estuarine area (Gola del Ter) and a point located 4 km upstream in the area of the Mas Capellana. Were observed a seasonal pattern where the maximum recruitment of glass eels in the estuary of the Ter occurs in late fall and winter (October-February) and a minimum in the spring. There is also a daily pattern of variation of the catch from the sun, recording an increase of individuals during the second hour of sampling; whereas, the increase in Capellana is the third hour. The results also show that during the first hour of sampling the river glass eels penetrate better somatic condition and along a half times the weight of the eels decreases. Were analyzed the biometrics of the species in relation to the evolution of the length, weight and color pattern. The medium data of length, weight and somatic condition were highest in the period of recruitment and more were falling progressively advanced accordance month sampling to reach minimum values in the spring. Among the captured units, described seven stages of pigmentation (VA, VB, VIA0, VIA1, VIA2, VIA3 and VIA4). The pigmentation stadium was more abundant in the VB stage on the temporarily series and during the summer months was when it were captured individuals stages more developed that indicate that individuals spent greater time in the estuarine area. Were carry out experimental fishing in two different phases of the moon, full and new, to determine whether there was a pattern with different light intensity favored the migration of glass eels and full moon is observed that most individuals captured although that would require a more detailed study on the influence of environmental factors that determine the entry of glass eels