Ictiofauna e ecologia trofica de peixes em ambientes praiais da Ilha das Peças, complexo estuarino de Paranagua, Parana
Resumo
The study took place between 20005 and 2006, in three areas: Pontal do Sul,
Barrancos and Shangrilá and the main aim was to evaluate discards production and
the interaction of seabirds with fisheries discards on the Parana coast. The methods
were based on three different focuses: (1) discards composition, through direct
observations in field and manipulation of discards samples in laboratory referring to
each area. (2) the use of those discards by seabirds on the shore line and at open
sea were evaluated through weekly counts on the shore line and monthly counts on
the open sea and (3) the reproduction of Larus dominicanus was evaluated during
montly samples in the Archipelago of Currais during its breeding cycle. The discards
composition was identified as 96 species of fish based on field samples and 70
species of fish based on laboratory samples, mainly in the form of whole fish.
Extrapolating the value of discard produced by fisheries activities in the present area
based on laboratory samples we obtained an annual discard production of 129.529.6
Kg. In relation to the interaction on the shore line, we counted nine species of birds
using discards, with numeric prominence for Kelp gulls, Larus dominicanus,while on
the open sea we observed eight species of birds, with Fregata magnificens and Sula
leucogaster being the predominant species. Kleptoparasitism behaviour was
observed mainly in intraspecific interactions on the shore line (78,69%), as on the
open sea (71,92%). There was a tendency of higher levels of kleptoparasitism during
the moratorium period, a situation where trawling activity is not permitted. The first
indications of reproduction, was represented by pair flight and courtship, these were
observed during May and June. Construction of the first nests, and the beginning of
egg laying, occurred in July, with reproductive peak in September. We counted 45
nests distributed accross four areas, located in the periphery of the island, close to
the water. In relation to weight, width and length we obtained mean values of
84,42mm±8,83 g, 49,30±1,78mm e 70,89±3,20mm respectively. During December
the last indications of reproduction were observed, represented by completely
feathered nestlings and beginning the first flights.
Collections
- Teses & Dissertações [10016]