The precautionary principle in fisheries management

The precautionary principle has become a reference rule for public actions and policies. Two conceptions coexist under this principle. The first one, based on the strengthening of the concept of environmental protection, aims to promote a prevention proportional to the potential risks. The second one looks for the eradication of risks and it may even require the “proof demand” of innocuousness. The application of the precautionary principle in the fishing sector became established as a reaction in view of the state of resources and the lack of efficacy to guarantee the sustainability of the exploitations. This document tries to stress the application of the precautionary principle in the framework of fisheries. First, it examines the concept of precaution, then it evaluates the concepts applied in the community policy, and thirdly, it concludes by pointing out the problems derived from its implementation.     

The impact of commercial and recreational harvesting for Paracentrotus lividus on shallow rocky reef sea urchin communities in North-western Sardinia, Italy

The fishery for the edible sea urchin Paracentrotus lividus is of great importance to many European regions, although in some of them this species has shown a wide scale decline in recent years. This paper reports on direct (on P. lividus) and indirect (on the co-occurring but not fished echinoid, Arbacia lixula) effects of sea urchin harvesting in shallow rocky reefs in North-western Sardinia (Italy, central-western Mediterranean Sea), where this activity is intensively practised. Density, size (test diameter), and biomass of both species were assessed in autumn 2004 at two locations impacted by P. lividus fishery, and at two controls within an adjacent Marine Protected Area. Density of P. lividus and A. lixula was significantly greater at the controls than at the exploited locations. The average test diameter of P. lividus was also significantly larger at the controls, where large-sized specimens (i.e. >5 cm) were notably more abundant. The average size of A. lixula did not significantly differ between the impacted locations and the controls. The average biomass of P. lividus was significantly greater at the controls than at the exploited locations, whereas no differences were detected for A. lixula. These results reveal the existence of a heavy fishing impact on P. lividus in North-western Sardinia and the need for regulation of its harvesting to prevent severe direct effects on its populations. Since no indirect effects on A. lixula have been detected, it could be hypothesized that this species did not benefit from P. lividus fishery due to an only moderate competition for habitat and resources between these two echinoids. Implications for management of edible sea urchin fishery are also discussed.     

数理统计学方法在中国水产资源研究中的应用概述

数理统计学方法对于水产资源学的发展发挥了极其重要的推动作用。数理统计方法在中国水产资源学的应用．起步于50年代．发展于60到80年代，90年代以后进入了一个崭新的发展阶段。作为一个发展中国家，同世界其他国家相比．我们将面临着更多的机遇与挑战。