A total of 28.1% of the dolphins analyzed presented PD in their
stomach contents. PD was found only in stomachs, and no dolphins
presented obstructions or ulcerations in the digestive tracts. Packaging
debris was found in 64.3% of the dolphins, with a lesser proportion
of dolphins ingesting fishery-related fragments (35.7%) and
those of unknown source (25.0%). Packaging debris was constituted
mainly by cellophane bands (52%), bags (11.4%) and plastic
rubber bands (6.8%), whereas fragments of ropes (12.7%), monofilament
lines (8.1%) and nets (4.5%) represent the fishery-related
debris. A 4.5% of the fragments represent plastics of unknown
source.
The 53.6% of the dolphins had only one plastic fragment in the
stomach, whereas 46.4% had between 2 and 5 plastic items per
stomach. The overall mean was 1.81 ± 1.05 items per stomach. In
the 50% of the dolphins that had more than one fragment in their
stomach, they were of a different source. The size of PD found were
between 0.2 and 11.4 cm (7.45 ± 5.54 cm), with the cellophane
bands of cigarette packages being the longest (11.4 cm). PD surface
were less than 7.5 cm2 (2.01 ± 3.46 cm2) being the fragments of
plastic bags the biggest. The hard plastic fragments were less than
0.6 cm in length and 0.2 cm2 in surface.
Log-linear models revealed no association between sex, ecosystem
and source of the PD (Table 2). The proportion of dolphins with
PD was significantly dependent of total body length (Chi2 = 4.95;
df = 8; p = 0.025). The occurrence of PD rapidly increased in yearlings,
reaching maximum occurrences between 110 and 130 cm
of body length, with reduced smaller values in adult animals
(>130 cm) (Fig. 2). Diet composition showed no significant differences
between animals with and without PD in their stomachs (Table
3)