Estudo da influência das marés na abundância de capturas da pesca artesanal de arrasto para praia no distrito de Pebane, Província da Zambézia (2009-2016).

Abstract

A study on the influence of tides on the catch of artisanal trawling fishing for the beach in the District of Pebane, Zambézia Province in the period from 2009 to 2016, has been carried out through annual samplings. Data from the artisanal fishery sampling system of the Fisheries Research Institute of Zambézia were used in this study. It had as objectives: To relate the catches per unit of effort with the type of tide; describe the specific composition of the catches in each type of tide and describe the population structure of the main species caught by tide type. Annual catches (in kg) and yields (CPUE) were determined from the database and grouped by tide type (live and dead). The specific composition and mean sizes were compared by tide type (live and dead) and then the t test was used to determine statistical differences between the average sizes of the nine monitored species Thryssavitrirostris (Crystal Ocar), Thryssa setirostri (Ocar horn) Arius dessumier (African Catfish), Sillagosihama (Common shrimp), Penaeusindicus (White shrimp), Penaeusmonodon (Tiger shrimp), Hilsakelee (Magumba), Sardinellaabella (white Sardine), e Pelonadichella.The results of the present study show that the largest catches were found in live tide in relation to dead tide, the population structure of these species is composed of small individuals that have not yet reached maturity (optimal catch sizes), Arius dussumier (35 , 7 ± 12.3 cm for live tide and 36.8 ± 8.2 for dead tide), Thryssavitrirostris (13.4 ± 10.9 cm for live tide and 14.2 ± 1 cm for the dead), Thryssasetirostris (14.9 ± 11.5 cm at dead tide 14.0 ± 10.9 for live), Penaeusindicus (15.8 ± 6.5 cm at dead tide, 30.2 ± 7.714286 at live tide), except the tiger shrimp (Penaeusmonodon), which had the highest average lengths of 32.4 ± 12.7 cm in the living tide and 21.4 ± 9.4 cm for the dead, and the t test showed highly significant differences in their size mean in the living tide dead in relation to the living tide with (t = 3.3559 and p = 0.0028). Catches per unit of effort in the two tides did not differ statistically (t = -0.17061 and p = 0.433487).