Weight-length relationship of 63 demersal fishes on the shallow coast of Parana´ , Brazil

Timbo´ ⁄ SC, BrasilSummaryThis work presents the weight–length relationship of 63 speciesof fish belonging to 24 families. Data were collected monthlyalong the Parana´state coast (Brazil) from August 2004 to July2005 on five transects between 6 and 15 m. Several of thesespecies had no previously published weight–length relation-ships.IntroductionWeight–length relationships are used by researchers to esti-mate weight from a given length (Froese, 2006). The objectiveof the present study was to establish the weight–lengthrelationships for 63 fish species from the shallow continentalshelf of the Parana´ state coast (Brazil).The continental shelf of the Parana´ state coast is character-ized, for the most part, by a covering of sand, mud and clay(Matsuura, 1986). According to Figueiredo (1981), the Parana´state coast contains the southern boundaries of tropical speciesdistribution, the northern boundaries of temperate forms and aseries of endemic species.Materials and methodsFour 15-min bottom trawls on five transects were carried outmonthly parallel to the coast at depths of 6, 9, 12 and 15 m(25 20¢⁄48 07¢;2546¢⁄48 30¢). Sampling was conducted usingtwo commercial trawl nets.Fish from each sample were packed in labeled plastic bagsand taken to the fish biology laboratory of the Centro deEstudos do Mar – UFPR for analysis. They were identified tothe species level according to Figueiredo (1977), Figueiredoand Menezes (1978, 1980, 2000), Menezes and Figueiredo(1980, 1985) and Menezes et al. (2003). The species in thisstudy were reviewed as regards the taxonomic classificationand the nomenclature based on FishBase. Total length (cm)(from the tip of the snout to the end of the caudal fin),standard length (cm) (from the tip of the snout to the end ofthe vertebral column) and weight (g) data were obtained fromeach specimen (sample chosen randomly and up to a maximumof 30 samples per species).The presence of outliers for each species that presented nineor more captured fish (66 species) was verified using totallength (TL) and weight (W) data (log-transformed and plottedgraphically) (Giacalone et al., 2010). Species in which thenumber of captured fish was fewer than nine after theexclusion of the outliers were excluded from the analyses,with 63 species distributed in 24 families remaining. Theadopted model was: (log W = log a + b*log TL), where W isthe weight in grams, TL the total length in centimeters, a theconstant and b the allometric coefficient (King, 1995; Froese,2006). These last two values were estimated using a linearregression analysis (program Excel, 2007) (Giacalone et al.,2010).Results and discussionA total of 23 654 fish was analyzed (Table 1). They belongedto 63 species, nine of which (Anchoa spinifer, Aspistorluniscutis, Narcine brasiliensis, Oligoplites saliens, Ophioscionpunctatissimus, Rypticus randalli, Rhinobatos percellens, Tri-nects microphthalmus and Zapteryx brevirostris) had noweight-length data recorded in FishBase or in the literature.The extreme b-values may be caused by narrow length-ranges(CitharichthysspilopterusandAnchoalyolepis),orwherethere were only juveniles (Cynoscion leiarchus and Selenesetapinnis). Comparing the obtained b-values with publishedvalues (3.135 ± 0.050 for C. spilopterus, 3.101 ± 0.121 forA. lyolepis, 2.872 ± 0.019 for C. leiarchus and 2.796 ± 0.016for S. setapinnis; Joyeux et al., 2009; Muto et al., 2000), it isimportant to emphasize that these LWR estimates in particularshould not be used outside the length range given.AcknowledgementsThe authors thank H.A. Pichler, S.B. Stoiev, C. Bernardo,L.O. Santos, G.M.L.N. Queiroz and C. Santos for assistancein field collections and laboratory analyses. A.C. Passos andR. Schwarz Jr. acknowledge financial support by the CAPES.References