IBS   24490
INSTITUTO DE BIOLOGIA SUBTROPICAL
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Using opportunistic records from a recreational fishing magazine to assess population trends of sharks
Autor/es:
SANTIAGO A. BARBINI; LUIS O. LUCIFORA; DANIEL E. FIGUEROA
Lugar:
Chattanooga
Reunión:
Encuentro; 30th Annual Meeting of the American Elasmobranch Society and 94th Joint Meeting of Ichthyologists and Herpetologists; 2014
Institución organizadora:
AES y otras
Resumen:
Detecting and determining changes in the occurrence and abundance of species is prioritary for effective management of the resources and conservation of the biodiversity. In the absence of long-term monitoring data, potential population declines may be very difficult to establish. Therefore, alternative information on occurrence of species to infer population trends is highly valued. We reviewed records of sharks (i.e. Notorynchus cepedianus, Carcharias taurus, Galeorhinus galeus and Carcharhinus brachyurus), from a recreational fishing magazine (Weekend) off northern Argentina, between 1973 and 2008, with the aim of evaluating population trends with opportunistic data sources. For each shark species, the number of occurrences per year in the magazine was registered. Our analyses were based on a non-probabilistic method (McPherson & Myers? approach) designed to determine population trends with opportunistic sighting records. In this approach we included the number of classified offering fishing guide services published per year in the magazine, as a measure of observation effort. Alike, for each species, we fitted generalized linear models with a Poisson error structure and a log link, where response variable was the number of occurrences per year, the explanatory variable was the year and the logarithm of the number of fishing guide ads was specified as an offset in each model. For both approaches, our models estimated that populations of the four shark species have suffered declines. Estimates produced by these models will help to determine the magnitude of population changes where a paucity of data prevents more precise analysis.