Measures of fishing fleet diversity in the New England groundfish fishery

After 16 years under a limited access program with effort controls, the New England groundfish fishery transitioned to a catch share management system in 2010. For much of its earlier management history, issues related to fishing capacity were paramount as effort controls were increasingly restrictive to meet biological objectives. As the size of the active fleet declined from over 1000 vessels from 1994 to 2001 to less than 400 vessels in 2012, the management concern shifted to fleet diversity. Fleet diversity has been cast in terms of vessels based on characteristics such as size, gear, and region rather than their share in landings or economic value. Measuring fleet diversity with indices commonly used in the biodiversity literature such as richness, effective diversity based on the Shannon index, and evenness appears appropriate for this context. In this paper these indices were applied to measure changes in diversity of the active New England groundfish fleet from 1996 to 2012. Fleet diversity as measured by the Shannon Index has declined by approximately 35% from 1996 to 2012, but has remained relatively stable since 2007. Forty vessel types were present in all 17 years, which accounted for about 85% of active groundfish vessels and over 90% of total groundfish landings in all years. Even though the fleet size and overall diversity have declined the “core” groundfish fleet remains stable.     

Trace-element distribution in the continental-shelf sediments off the east coast of India

Thirty continental-shelf clays sampled off the east coast of India have been analysed spectrographically to determine the concentrations of Ge, Ga, Pb, Cu, Mo, Sn, V, Ni, Co, Zr, Cr, Ba, Sr and B. Most of these elements are detrital in origin and are primarily held up in clay minerals or adsorbed onto the clays in the nearshore mixing zone. Organic matter influences the concentrations of Ge, Sn, and to a lesser extent, Ga and Pb in the shelf.     

琼东沿岸泥质沉积常量元素地球化学特征

对南海北部陆架琼东沿岸泥质区$20孔进行了岩性、粒度和常量元素分析,初步探讨了该泥质区常量元素地球化学特征.S20孔岩性较均一,主要为黏土质粉砂,研究区受相对单一而稳定的水动力条件控制.常量元素含量变化符合“元素的粒度控制律”,R型因子分析结果表明,第一因子P2O5,MnO,TiO2,A12O3,Fe2O3和K2O等的...