Fisheries Research 69 (2004) 371–379 Morphometric relationships of the European spiny lobster Palinurus elephas from northwestern Sardinia C. Tidu a,b,∗ , R. Sard´ a a , M. Pinna c , A. Cannas d , M.F. Meloni b , E. Lecca b , R. Savarino b a Centre d’Estudis Avan¸ cats de Blanes, Consejo Superior de Investigaciones Cient´ ıficas, C.S.I.C., Carrer d’Acc´ es a la Cala St. Francesc 18, 17300 Blanes, Girona, Spain b Cooperativa Acquacoltura e Ricerca, Via Brigata Sassari 31, 09045 Quartu Sant’Elena, Cagliari, Sardinia, Italy c Universit` a degli Studi di Lecce, Dipartimento di Scienze e Tecnologie Biologiche ed Ambientali, Via Monteroni, 73100 Lecce, Italy d Centro Italiano Ricerche e Studi sulla Pesca., Via De Gigli d’Oro 21, 00186 Roma, Italy Received 30 June 2003; received in revised form 7 May 2004; accepted 17 May 2004 Abstract Two morphometric relationships, carapace length versus total length (CL versus TL), and carapace length versus weight (CL versus W), were estimated for the spiny lobster Palinurus elephas fished in northwestern Sardinia. The calculations were done for both sexes and for the years 1998 and 1999. The power function y = ax b was used in both relationships. The first derivate dY/dCL = abCL b -1 , where Y is either TL or W was used to study the growth tendency of TL and W in relation to CL. The results showed no interannual differences in the CL versus TL relationship for both sexes. A negative allometry, b < 1, was found for males which was also reflected in their decreasing growth rate of TL in relation to CL. However, this negative allometry would not have been detected if the function y = a +(bx) had been used since it yields only isometric growth. Conversely, the CL versus W relationship showed significant interannual differences for both sexes and a general negative allometry, b < 3. This negative allometry was more stressed for males in both years which also was reflected in their lower W growth rate in relation to CL. Consequently, for a better estimation of the W from the CL versus W relationship it is recommended to calculate this yearly using local values, and limiting the application of the calculated regression only to the range of measures employed. Finally, the use of some condition indices in relation to the negative allometry and the interannual variability in the CL versus W relationship is also discussed. © 2004 Elsevier B.V. All rights reserved. Keywords: Palinurus elephas; Spiny lobster; Morphometric relationships; Northwestern Sardinia ∗ Corresponding author. E-mail address: carlo@ceab.csic.es (C. Tidu). 1. Introduction The spiny lobster Palinurus elephas is widespread in the western Mediterranean Sea, from the Strait 0165-7836/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.fishres.2004.06.003