Abstract
The biology and fishery of the lobster, Palinurus elephas from the SW coast of Portugal was studied during two distinct periods 10 years apart in 1993-1994 (March 93 to March 94) and during 2003 (May to July). The landings at the port of Sagres, representing half of the catch of the country for this species, were sampled twice a week. The ovigerous season extends from September to March, with an individual incubation period of five months. Considering the ovigerous condition as an indicator of maturity in females, 50% of the females were mature at carapace length of 110 mm. Females below this size represent 95% of the population and account for 41% of the egg production. Females above 50% maturity, representing only 5% of the population, provide 59% of the eggs, showing the importance of larger individuals in the reproduction of this species. Most biological parameters estimated are within the range of values reported for this species in other areas with the exception that in our study the total length was smaller in relation to carapace length, so that females of a given carapace length carried fewer eggs. Parameters were estimated for the following relationships: total length and carapace length, weight and carapace length, weight and total length, maturity at size (carapace length) and fecundity at size (carapace length). It is suggested that a set of measures including catch control, effort control, gear control and protected areas are combined to allow the recovery of this resource.
Highlights
The spiny lobster Palinurus elephas (Fabricius, 1787), previously known as Palinurus vulgaris, is common along the Northeast Atlantic coasts (Ireland and South of England), Azores and down into the Mediterranean to the Greek Islands (Chace and Dumont, 1949; Marin, 1985; Hunter, 1999)
This was not observed in the samples of 1993 and 2003, where the proportion of females decreased to 52% and 41% (Fig. 2) and the larger classes are dominated by males
Goni et al (2003a) reported differences in the efficiency of traps and fixed nets, with traps having lower catch rates for larger males only. This can explain the loss of dominance of females in larger classes from 1958 to 1993-2003, and should be taken into consideration when interpreting variations in maximum and average sizes and sex ratios
Summary
The spiny lobster Palinurus elephas (Fabricius, 1787), previously known as Palinurus vulgaris, is common along the Northeast Atlantic coasts (Ireland and South of England), Azores and down into the Mediterranean to the Greek Islands (Chace and Dumont, 1949; Marin, 1985; Hunter, 1999) It is a temperate water species living on the continental shelf at depths varying with age and latitudinal distribution, being common in waters to depths of 160 m with higher concentrations between 10 and 70 m (Bouvier, 1940; Ficher et al, 1987). For the Portuguese coast only one study has been published to date (Vasconcellos, 1960) resulting from sampling landings in the port of Sines from mid July to early October in 1958 This species is an important resource in the SW coast of Portugal. At that time it was already considered a valuable resource, supporting the fishing activity of both Portuguese and French fleets
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