DIETS OF LAGOON FISHES OF THE SOLOMON-ISLANDS - PREDATORS OF TUNA BAITFISH AND TROPHIC EFFECTS OF BAITFISHING ON THE SUBSISTENCE FISHERY

Analyses of the stomach contents of 122 species of predators from fringing reef lagoons of the Solomon Islands showed that 45 species ate baitfish species caught commercially. Baitfish (mainly Stolephorus and Spratelloides species) comprised nearly 25% by weight of their combined diets, but in only 28 of these predators were baitfish a major proportion of the diet. To simulate the subsistence fishery, fishing competitions (using drop-lining, spear-fishingand trolling) were held. A total of 183 species of 31 families was recorded. Drop-lining, the predominant technique, contributed most to the overall catch, although trolling was important in one area. Catches from traditional poisoning methods were also monitored. We concluded that most of the fish caught by the subsistence fishery do not eat baitfish. Some pelagic species, mainly Scombridae, are baitfish predators, but are caught only by trolling. Hence, unless there is a marked increase in trolling among subsistence fishermen, there is little evidence that the commercial baitfishery at present directly affects the food chain on which the subsistence reef fishery depends. © 1990.