Four 100 m lengths of both monofilament gill nets and trammel nets were deployed at depths between 15 and 18 m off the coast of the Algarve (south of Portugal) between April 1995 and June 1996. The nets were set on a natural rocky bottom with one end cut loose to simulate lost nets. Changes in net structure (net height, effective fishing area, movement, colonisation, wear and tear) and their catches (species, sizes, numbers, and biomass) were monitored by divers. Similar patterns were observed in all the nets, with a sharp decrease in net height and effective fishing area, and an increase in visibility within the first few weeks. Net movement was negligible except in the case of interference from other fishing gears. Catch rates were initially comparable to normally fished gill nets and trammel nets in this area, but decreased steadily over time. No sea birds, reptiles or mammals were caught in any of the 8 nets. Catches were dominated by fish (89 % by number, at least 27 species), in particular by sea breams (Sparidae) and wrasses (Labridae). Under the conditions experienced throughout the study the fishing Lifetime of a 'lost' net is between 15 and 20 wk. Based on an exponential model, we estimated that 100 m lengths of gill net and trammel net will catch 314 and 221 fish respectively over a 17 wk period. However, we consider this to be an underestimate due to high rates of predation and scavenging by octopuses, cuttlefish, moray eels, conger eels, and other fish such as the wrasse Coris julis. When the nets were surveyed in the following spring, 8 to 11 mo after being deployed, they were found to be completely destroyed or heavily colonised by algae and had become incorporated into the reef

Weight and length descriptive statistics are reported for 73 fish species discarded in the commercial fisheries from the south coast of Portugal. Parameters of the weight-length relationship were estimated for 57 of these species. These are the first weight-length parameters reported for 20 of these species. For an additional 16 species for which no weight-length parameters have been reported, the parameter a was estimated by setting b = 3.0. Samples were used from five gear types: crustacean trawler, fish trawler, pelagic purse seine, demersal purse seine and trammel net. Samples were obtained from depths ranging from 500 m and included pelagic and demersal species

In order to understand how marine ecosystems function, it is essential to study the trophic interactions among the community members, particularly from poorly known regions. In this study, the feeding ecology and diet of conger eels,Conger conger, an abundant fish species with commercial interest, was examined in the north-east Atlantic, off Algarve (southern Portugal) between May 2005 and August 2006. The diet was characterized by species composition, size and mass of prey. Conger eels are opportunistic feeders, cannibalistic, feeding on benthopelagic/pelagic prey (67% by mass and 71% by number) but also benthic prey (32% by mass and 29% by number). Fish (67.8±4.7% in mass) are the main prey of conger eels, followed by cephalopods (16.5±3.8%) and crustaceans (15.6±3.7%). The most numerous (identifiable) fish consumed wereCapros aper, occurring in 90% of the stomach samples that contained food and representing 1.4% in mass, andScomber japonicus, the most important fish in mass (21.1%), which occurred in 4.2% of the stomach samples that contained food. The present study shows that octopodids can play a more important role in the diet of conger eels than previously thought. Of the species preyed upon by conger eels, six species (21% of the total prey taxa) are caught commercially(Trachurus trachurus, Scomber japonicus, Micromesistius poutassou, Helicolenus dactylopterusandConger conger)by local fisheries. As discards by local trawl and longline fisheries do not correspond with the diet ofC. conger, it is likely that most prey ofC. congerin rocky areas were caught actively in that study region.