Ecology of the whiskered sole in the Sado Estuary, Portugal

Abstract

The abundance of the wiskered sole Monochirus hispidus in the Sado Estuary showed a marked seasonal pattern, the highest densities occurred in spring and summer. The density of this species was mainly related, non-linearly, to depth, water transparency and percentage of gravel, fine sand and mud in the sediment. Monochirus hispidus fed mainly on crustaceans and polychaets. Significant differences were found between the proportions of prey items eaten and total length class; larger fish consumed more decapods and polychaets. The von Bertalanffy growth equation coefficients differed between sexes. The asymptotic length L 1 obtained for females was higher compared to males, while the growth coefficient (K) was higher for males. Individuals with mature gonads were found between March and September, but the main spawning period of M. hispidus in the Sado Estuary was from March to June. # 2004 The Fisheries Society of the British Isles

Adapting a growth equation to model tree regeneration in mountain forests

“…For biological applications it is often preferable to use a growth equation that is simple, with only few parameters to estimate, but still describing the process with sufficient accuracy (Zeide 1993). The Bertalanffy equation (Bertalanffy 1957) has frequently been used to model different organisms (fish: Amaral and Cabral 2004;lobsters: Cheng and Kuk 2002;thistles: Rees et al 1999), and has also been broadly used to describe tree growth (Zeide 1993;Zhang et al 1996). It is theoretically derived from physiological mechanisms of growth Bertalanffy 1957).…”

“…The equation has often been used to model growth processes of organisms such as fish (e.g. Amaral and Cabral 2004), herbs (Rees et al 1999), and has also been applied to trees (Zeide 1989(Zeide , 1993Kahn 1994).…”

Validation of age determination methods and growth studies of the sand sole Pegusa lascaris (Soleidae) from the eastern-central Atlantic

“…These estimations suggest that the von Bertalanffy model does not accurately describe growth in the early stages. Negative values of t 0 are frequent among flatfishes with rapid growth during the first year and slow growth in the following years (Dwyer et al 2003, Amaral and Cabral 2004, Teixeira et al 2010.…”

“…La diferencia observada entre el crecimiento de machos y hembras, las cuales alcanzan mayor talla y edad que los flatfishes (Amaral andCabral 2004, Teixeira et al 2010). The difference in growth between sexes can produce an overestimation of the growth in mixed samples since females predominate in sizes over 22 cm (Pajuelo and Lorenzo 2008).…”

“…The hydrological conditions of the Tagus Estuary are under Atlantic influence and the individuals of P. lascaris can move among neighbouring areas but also toward open Atlantic waters of the Portuguese coast (Amaral and Cabral 2004). The differences observed in the studies carried out on the west coast of Brittany by Deniel (1990) for P. lascaris can be attributed to the differences in the environmental conditions between the Atlantic Ocean and the west coast of Brittany, where flatfish have found especially suitable hydrological and sedimentary conditions in which to settle (Deniel 1990).…”