Nets’ catching efficiency in both bottom types showed a negative exponential decrease pattern over time, which was more
pronounced in the nets set in the sandy bottom (Fig. 5). Initial
catch rates were comparable to those of control nets. Considering
catching efficiencies of experimental trammel nets in both bottom
types, maximum values were attained at the fifth day of immersion
(rocky bottom 96.7%; sandy bottom 86.7%). Over the first 15 days,
the catching efficiency was reduced to about 46.2% (rocky bottom)
and 41.1% (sandy bottom), followed by an increase reaching 73.3%
in the case of trammel nets set in the rocky bottom. After 60 days,
catching efficiency of both groups of nets was similar: 17.9% for rocky bottom nets and 13.3% for sandy bottom nets. The reduction
of the relative catching efficiency was then less strong, presenting values near 0 at the end of the experiment for nets set in the
sandy bottom. Concerning nets set in the rocky bottom, and after an
increase at 80th day, catching efficiency decreased again stabilising
at about 2.2%