Data/hora: 08/06/2024 09:46:19

Provedor de dados: | 20
País: | Belgium

Título:

Características ecológicas del pulpito Octopus Tehuelchus en tres ambientes del golfo San Matías

Ecological characteristics of pulpito Octopus Tehuelchus in three environments of San Matías gulf

Autores: | Storero, L.P.
Data: | 2013-08-28
Ano: | 2010
Palavras-chave: | Fishery biology; Cephalopod fisheries; Artisanal fishing; Coastal zone management; Coastal environment; Environmental conditions; Population dynamics; Sex composition; Spatial distribution; Morphology (animal); Life cycle; Feeding; Size-at-first-maturity; Age determination; Growth; Reproduction; Reproductive behaviour.
Resumo: | Coastal marine ecosystems are highly variable and the inherent biotic and abiotic factors of these environments can influence the bio-ecological characteristics of the living cephalopods. The presence of the small octopus “pulpito” Octopus tehuelchus in the coastal environments of San Matías Gulf has been exploited by artisanal fishermen for more than 60 years. The aim of this study is to evaluate the variations in the life cycle of the pulpito, and the factors that could account for these variations in three different coastal environments of San Matías Gulf, with differences in the physical, ecological and fisheries characteristics. This study was developed in San Antonio bay, El Fuerte and Islote Lobos. Monthly samplings (October 2005-2007) in the intertidal sector of each study site were done, and all the octopuses present along transects were collected. To evaluate the biological and population characteristics, morphogravimetic measures were taken of each individual, and the stomach contents and ovaries were analyzed. Also, the oceanographic, structural, ecological and fisheries characteristics of each site were recorded. Phenotypic plasticity in response to environmental variability seems to be one of the main characteristics of the pulpito. In Islote Lobos the smaller sizes and short life span, which is related with small size at maturity and low fecundity, could be a consequence of the low temperature in the south sector of the gulf. This determines lower growth rates, and jointly with the lower prey availability, produce smaller octopuses than the ones observed in other sites. Moreover, the high parasitic infection affects the octopus’s condition. The last, together with the high predation pressure, would diminish the survival and life span of the pulpito in Islote Lobos. In El Fuerte the pulpito presents the highest growth rates, which originates larger octopuses with high gonadosomatic and condition indices during the maturing and spawning season. In this site, the highest recruitment rates were observed, which could be favoured by high survival due to low predation pressure and low parasitic infection. Also, increasing seawater temperature during summer, jointly with high prey and refuges availability would favour the high growth rates and densities, which allow high fishery exploitation. In contrast with the other sites, the wide temperature and salinity ranges observed in San Antonio bay, promote the development of two sub-annual cohorts with different growth pattern depending on the date of birth. This also causes a different pattern in gonadosomatic and condition indices, and different sizes at maturity between sexes. On the other hand, the lower refuge availability jointly with high densities during summer months, favour the development of a pot-longline fishery of high intensity in the last few years. These results suggest that a specific management strategy that ensures the sustainability of the populations and its ecosystems should be elaborated. Also, in this strategy, interaction of fisheries with other coastal activities and the particular biological and population characteristic of the pulpito in each environment should be taken in to account.
Tipo: | Theses and Dissertations
Idioma: | Espanhol
Identificador: | http://hdl.handle.net/1834/5023
Formato: | 194
Fonte: | http://creativecommons.org/licenses/by-nc/3.0/