Swallowing the bait: Is recreational fishing in Australia ecologically sustainable?

Recreational fishing is a growing component of the total fishery harvest in many countries, but the impacts of this sector on aquatic resources are often ignored in the management of aquatic systems. Recreational fishing is open-access, and in many inshore regions, the recreational harvest exceeds the commercial harvest. The environmental impacts from recreational angling can be both ecologically significant and broad in scope and include: the removal of a considerable biomass of a wide variety of species; discarded by-catch; possible trophic cascades through the removal of higher order carnivores; impacts on habitat through bait harvesting; impacts of introduced and translocated species to support angling fisheries; direct impacts on sea-birds, marine mammals and reptiles; and angler generated pollution. Management, for several reasons, has largely ignored these environmental impacts from recreational fishing. Recreational fishing impacts are cumulative, whereas there is a tendency for consideration of impacts in isolation. Recreational fishing lobbyists have generally been successful in focusing public and political attention on other impacts such as commercial fishing, and recreational fishing has tended not to come under close scrutiny from conservation and environmental groups. Without changes to the monitoring and management of recreational fisheries that incorporate the broad ecological impacts from the activity, it may not be ecologically sustainable in the long term and Australia will not meet its international obligations of protecting aquatic biodiversity. The definition of property rights and appropriate measures to prevent or manage large scale marine restocking are two emerging issues that also need to be addressed

Schizophrenia copy number variants and associative learning

Large-scale genomic studies have made major progress in identifying genetic risk variants for schizophrenia. A key finding from these studies is that there is an increased burden of genomic copy number variants (CNVs) in schizophrenia cases compared with controls. The mechanism through which these CNVs confer risk for the symptoms of schizophrenia, however, remains unclear. One possibility is that schizophrenia risk CNVs impact basic associative learning processes, abnormalities of which have long been associated with the disorder. To investigate whether genes in schizophrenia CNVs impact on specific phases of associative learning we combined human genetics with experimental gene expression studies in animals. In a sample of 11 917 schizophrenia cases and 16 416 controls, we investigated whether CNVs from patients with schizophrenia are enriched for genes expressed during the consolidation, retrieval or extinction of associative memories. We show that CNVs from cases are enriched for genes expressed during fear extinction in the hippocampus, but not genes expressed following consolidation or retrieval. These results suggest that CNVs act to impair inhibitory learning in schizophrenia, potentially contributing to the development of core symptoms of the disorder

Structure of macrobenthic communities in relation to historical patterns of dredging in the Brisbane River estuary

The composition of the benthic assemblages found along the margins of the Brisbane River estuary was examined to determine whether there were any relationships with the historical patterns of extractive dredging in the river. Three categories of treatment were used: control zones which had never been used for extractive dredging; recently dredged zones which had been dredged in the previous 2 years; and previously dredged zones which had been dredged within 3-5 years. A total of 3,113 animals was collected from 64 benthic grab samples, with the fauna dominated by spionid polychaetes (lower reaches) and tanaid crustaceans (upper reaches). The composition of the benthic assemblages in the up-and down-river sections was significantly different from each other, so analyses comparing the three treatments were done separately for the two sections. Multivariate and univariate analyses indicated that there were significant differences among the different zones in the numbers and types of animals found there, but these differences were not correlated with the dredge history for the zones. In each case, zones with a similar dredge history were as different from each other as they were from zones with a different historical pattern of dredging

Depletion of benthic invertebrates by bar-tailed godwits Limosa lapponica in a subtropical estuary

This study (1) investigated functional (capture rate, foraging success) and numerical (density) responses of bar-tailed godwits Limosa lapponica to an experimental decrease in densities of their prey, and (2) estimated seasonal depletion of the stock of their main prey, the mictyrid crab Mictyris longicarpus, in a subtropical estuary. It was predicted that if intake rates of the godwits are in the vicinity of the gradient section of a functional response curve, i.e. are directly determined by prey density, they will respond rapidly to experimental reduction in the density of their prey. Bar-tailed godwits did respond rapidly, both functionally and numerically, to a decrease in the density of M longicarpus, indicating that their intake rate was limited by food availability. The estimated seasonal depletion of the stocks of Mictyris by the godwits was 88 % of the initial standing stock. Despite the virtual disappearance of Mictyris from sediment samples through the course of a non-breeding season, local densities of godwits did not change between October and March, implying that adequate rates of intake could be maintained throughout their residence period

Mapping intertidal habitats and an evaluation of their conservation status in Queensland, Australia

The goal of biodiversity conservation has been described as the conservation of diversity at three levels: ecosystem, species and genetic diversity. Developing a representative system of marine protected areas (MPAs) is considered an effective way to achieve this goal in the marine environment. In the absence of detailed information relating to biological distributions there has been increasing use of biodiversity surrogates to determine MPA priorities at regional levels. The development of biodiversity surrogates at fine scales (i.e. habitats) will have an increasingly important role in the identification of sites that will contribute to a representative system of MPAs. This is because it will increase the likelihood that the system will adequately achieve biodiversity objectives by ensuring protection of a greater range of habitats and species. This article provides an explanation of an intertidal shoreline habitat surrogate used to describe 24,216km of Queensland's coastline. The protective status of intertidal habitats was evaluated to assist with designing a representative system of intertidal MPAs. (C) 2002 Elsevier Science Ltd. All rights reserved