الفهرس 
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Abstract
Fisheries management and research often require the use of biometric relationships in order to transform data collected in the field into appropriate indexes (Anderson and Gutreuter, 1983; Ecoutin and Albaret, 2003). One of the most commonly used in any analysis of fishery data is the weight–length (W–L) relationship (W = aLb). According to Andrade and Campos (2002), this is particularly useful when sampling large species, because of the difficulty and time required to record weight in the field. Besides the estimation of weight from length (Beyer, 1991; Martin-Smith, 1996), the W–L relationship has several applications, including the conversion of a growth equation in length into a growth equation in weight (Pauly, 1993; Pérez and Contreras, 1995; Merella et al., 1997). Establishment of a relationship between weight and length is essential for the calculation of production and biomass of a fish population (Anderson and Gutreuter, 1983; Safran, 1992; Petrakis and Stergiou, 1995; Dulčić and Kraljević, 1996; Moutopoulos and Stergiou, 2002), allowing also for morphological comparisons among species or among populations of the same species from different habitats and/or regions (Gonçalves et al., 1997; Moutopoulos and Stergiou, 2002). It is frequently used to follow seasonal variations in fish growth and to estimate condition indexes (Anderson and Gutreuter, 1983; Safran, 1992; Richter et al., 2000). Estimates of the relationship parameters a and b can be related to ecological processes and life history.
Previous studies were carried out on the characterization of W–L relationships for fish species in Portuguese waters, e.g. Santos et al. (2002) and Borges et al. (2003) in the Algarve (southern Portugal), Gonçalves et al. (1997) in the southwest and southern coasts and Morato et al. (2001) in the Azores Islands. In the present work, W–L relationships were estimated for 46 fish species captured off the west Portuguese coast, representing the first information available on W–L relationships for 13 species (Acantholabrus palloni, Anthias anthias, Chelidonichthys cuculus, Labrus mixtus, Microchirus ocellatus, Mic. variegatus, Mullus barbatus, Phycis blennoides, Scorpaena scrofa, Pegusa lascaris, Solea solea, Trisopterus minutus and Uranoscopus scaber) for the Portuguese continental coast. Also, to the best of our knowledge, this study presents the first reference on the W–L relationship worldwide for the swallowtail sea-perch (A. anthias).