Codend selection in American plaice: diamond versus square mesh

Abstract

Codend selection in American plaice, (Hippoglossoides platessoides), was studied using the trouser trawl method. Mesh selection studies were carried out using 130 mm, 140 mm and 155 mm diamond and square mesh codends in experiments off the east coast of Canada in 1988 and 1990. Selection curves and selection parameters were calculated using a modified logistic model which allows for calculation of standard errors. The split of fish into the two codends (large mesh and small mesh) was estimated and tested for significant departure from the 50:50 split assumption in trouser trawl catches. Fifty percent retention lengths and selection factors were higher for diamond mesh codends than square mesh codends, implying that square mesh retains more smaller American plaice than diamond mesh codends. The implication of introducing square mesh codends in a mixed fishery is discussed.