SOAK TIME AND NET LENGTH EFFECTS ON CATCH RATE OF ENTANGLING NETS IN CORAL-REEF AREAS

The effects of net length and soak time on fish catches of gillnets and trammel nets were studied in a coral reef off La Parguera on the southwestern corner of Puerto Rico. Gillnets and trammel nets were varied in length from 100 to 300 fathoms in intervals of 100 fathoms. Net length significantly affects the number of fish caught by these nets, but no significant differences in catch per unit effort were observed on a per length basis. For the soak time experiment, gillnets and trammel nets of 100 fathoms were set for 24 h. A visual census of the nets was carried out during the afternoon, at sunset and at sunrise. The saturation effect of decreased catch with increasing soak time did not occur. The efficiency of gillnets was variable over time but differences were not significant. The efficiency increased at the shortest time (6-10 h), decreased at the intermediate time (10-15 h), and increased again at the longest time (15-20 h). Changes in trammel net catch rates were negligible. A significant difference was found between visual census and gillnet catch in the number of individuals and species observed. These results appear to be influenced by some unmeasurable and unrecorded factors such as method of deployment of the nets, fish behavior around the nets and type of substrate.