S. Jennings et Nvc. Polunin, EFFECTS OF FISHING EFFORT AND CATCH RATE UPON THE STRUCTURE AND BIOMASS OF FIJIAN REEF FISH COMMUNITIES, Journal of Applied Ecology, 33(2), 1996, pp. 400-412
1. An improved understanding of fishing effects is required to assess
the sustainability of existing fishing practices and to determine the
ecological implications of offering fishing concessions in marine rese
rves. 2. The effects of fishing were investigated in six Fijian fishin
g grounds (qoliqoli) subject to different fishing intensities. 3. A vi
sual census technique was used to determine the structure and biomass
of the shallow-water reef fish communities targeted by the fishers. 4.
A supervised voluntary logbook scheme was used to assess the size and
composition of yield from the qoliqoli. 5. The fish communities in th
e least intensively fished qoliqoli were significantly different from
fish communities elsewhere. The significance of these differences was
attributable to the greater biomass of invertebrate feeding and pisciv
orous fishes in the least intensively fished qoliqoli. 6. Annual yield
s of herbivorous fishes ranged from 0.3 to 5.2% of the biomass estimat
ed by visual census. There were no significant differences in herbivor
e biomass among qoliqoli subject to different fishing intensities. 7.
The biomass of invertebrate feeding fishes was significantly higher in
the least intensively fished qoliqoli. The biomass of invertebrate fe
eding/piscivorous fishes was significantly higher in the two least int
ensively fished qoliqoli. 8. In the two least intensively fished qoliq
oli the estimated annual yields of invertebrate feeding and invertebra
te feeding/piscivorous fishes did not exceed 4% of the biomass estimat
ed by visual census. However, yields of these trophic groups approache
d 20% of biomass in the intensively fished qoliqoli where biomass was
significantly lower. 9. The fishing effects observed were primarily at
tributed to significant differences between the fish communities in th
e least intensively fished qoliqoli and all others. Thus, at higher fi
shing intensities, the biomass of target species provided a poor index
of relative fishing pressure. 10. The results suggest that the annual
removal of 5% of fish biomass may cause significant structural change
s in reef fish communities. Thus, it is important to ensure that fishi
ng concessions and poaching activities are carefully regulated in mari
ne reserves.