[Abstract] We test predicted short-term structural changes in the macroinvertebrate
assemblages of a shrimp fishing ground in the tropical Mexican Pacific subject to
low effort with seasonal closures. During two years, five cruises were carried out
sampling seven sites and four depths (20, 40, 60 and 80 m) along 100 km of
coastline. A series of community structure descriptors were used to determine the
ecological effects of fishing disturbances: ABC curves, W-statistic, normalized
species size distribution as biomass spectra, spatial segregation index, Shannon-
Wiener diversity index, species richness and biomass. Theoretical predictions of the
effects of fishing on these indices were tested by comparisons of samples collected
from successive open and close fishing seasons. ABC curves show fishing has
produced a state of chronic disturbance in the macroinvertebrate community. Shortterm
effects could be masked by natural seasonal and interannual environmental
changes. Results of the analyses of short-term effects are not in agreement with the
fishing disturbance theories; only in 31% of the cases the results obtained of
comparisons between successive cruises to test the different hypotheses about the
effects of fishing were in agreement with theory. The temporal trend of increase of
the biomass and the decline of species richness, could evidence interannual effects.
The complexity of the sources of variability in a exploited community forces to focus
on temporal and spatial gradients to understand the community structural
processe
