Length-weight relationships and condition factor of eight fish species inhabiting the Rocha Lagoon, Uruguay

Abstract

Length-weight relationships are commonly used in fisheries biology to convert length measures into weight and to ascertain the growth characteristics related to those variables. On the other hand, length-weight relationships are used for estimating fishes’ condition factor, and these values are used for comparing the “condition”, “fatness” or “well-being” of fish (LE CREN, 1951; FROESE, 2006). The condition factor could reflect the physiological state of a fish, which is influenced by both intrinsic (gonadal development, organic reserves, presence or absence of food in the gut) and extrinsic (food availability, environmental variability) factors (NIKOLSKY, 1969). The coastal lagoons on the south-eastern Uruguayan Atlantic coast (Jose Ignacio, Garzon, Rocha, Castillo, and Negra) serve as feeding (NORBIS; GALLI, 2004; OLSSON et al., 2013), reproduction (VIZZIANO et al., 2002), nursery grounds (SANTANA; FABIANO, 1999) and growing areas (BORTHAGARAY et al., 2011) for several marine and estuarine fishes which sustain local artisanal fisheries (SANTANA; FABIANO, 1999; SAONA et al., 2003; FABIANO; SANTANA, 2006). The Rocha Lagoon is a shallow, brackish, microtidal lagoon (area=72 km