Interaction between Coastal and Oceanic Ecosystems of the Western and Central Pacific Ocean through Predator-Prey Relationship Studies

The Western and Central Pacific Ocean sustains the highest tuna production in the world. This province is also characterized by many islands and a complex bathymetry that induces specific current circulation patterns with the potential to create a high degree of interaction between coastal and oceanic ecosystems. Based on a large dataset of oceanic predator stomach contents, our study used generalized linear models to explore the coastal-oceanic system interaction by analyzing predator-prey relationship. We show that reef organisms are a frequent prey of oceanic predators. Predator species such as albacore (Thunnus alalunga) and yellowfin tuna (Thunnus albacares) frequently consume reef prey with higher probability of consumption closer to land and in the western part of the Pacific Ocean. For surface-caught-predators consuming reef prey, this prey type represents about one third of the diet of predators smaller than 50 cm. The proportion decreases with increasing fish size. For predators caught at depth and consuming reef prey, the proportion varies with predator species but generally represents less than 10%. The annual consumption of reef prey by the yellowfin tuna population was estimated at 0.8±0.40CV million tonnes or 2.17×1012±0.40CV individuals. This represents 6.1%±0.17CV in weight of their diet. Our analyses identify some of the patterns of coastal-oceanic ecosystem interactions at a large scale and provides an estimate of annual consumption of reef prey by oceanic predators

A quantitative comparison of recreational spearfishing\ud and linefishing on the Great Barrier Reef: implications\ud for management of multi-sector coral reef fisheries

This study compared the catch composition, catch per unit effort, and incidental impacts of spearfishers and linefishers engaged in a structured fishing program whereby fishing effort was standardized across time, space and skill level. It was found that (1) the catch composition of both groups of fishers overlapped considerably, (2) the numbers of target fish caught by spearfishers (156) and linefishers (168) were not significantly different, (3) the\ud mean size of target fish caught by spearfishers (1.95 § 0.1 kg, §SE) was significantly larger than the mean size of target fish caught by linefishers (1.27 § 0.06 kg), and (4) spear-fishers retained 43% more biomass of target species than did linefishers (304 versus 213 kg, respectively). However, linefishers used »1 kg of bait for every 3 kg of target fish that were captured. Linefishers also caught far more undersized, undesirable, or protected fishes (i.e., bycatch) and caused far more pollution (i.e., lost gear) than did spearfishers. It is concluded that the overall impacts of recreational spearfishing and linefishing on fishery resources of the Great Barrier Reef are broadly equivalent (per unit of fishing effort), and that management regulations should be applied equitably across both fishing sectors. A management strategy of this type will simplify enforcement of fisheries regulations and avoid discrimination of particular fishers in local communities where both fishing methods are socially or\ud culturally important