Fish harvest tags: An alternative management approach for recreational fisheries in the US Gulf of Mexico

This paper explores the potential adaptation of harvest tags to the Gulf of Mexico recreational reef fish fishery. The discussion addresses conceptual, theoretical, and practical issues surrounding the application of harvest tags, as well as challenges and opportunities related to the design of tag programs. A review of hunting and fishing tag programs around the world and analysis of Gulf recreational fisheries suggests that tags have the potential to improve control over total catches, increase economic benefits and provide better information for fishery management. Results also provide insight into potential use of fish tags in large-scale recreational fisheries nationwide.     

Trend analysis using discrete wavelet transform (DWT) for long-term precipitation (1851–2006) over India

This study is an attempt to determine the trends in monthly, annual and monsoon total precipitation series over India by applying linear regression, the Mann-Kendall (MK) test and discrete wavelet transform (DWT). The linear regression test was applied on five consecutive classical 30-year climate periods and a long-term precipitation series (1851–2006) to detect changes. The sequential Mann-Kendall (SQMK) test was applied to identify the temporal variation in trend. Wavelet transform is a relatively new tool for trend analysis in hydrology. Comparison studies were carried out between decomposed series by DWT and original series. Furthermore, visualization of extreme and contributing events was carried out using the wavelet spectrum at different threshold values. The results showed that there are significant positive trends for annual and monsoon precipitation series in North Mountainous India (zone NMI) and North East India (NEI), whereas negative trends were detected when considering India as whole.

EDITOR A. Castellarin ASSOCIATE EDITOR S. Kanae     

Southwest Pacific subtropical mode water: A climatology

The large-scale distribution and changes in Southwest Pacific subtropical mode water (STMW) are investigated and discussed. The paper presents for the first time geographic maps showing the spatial distribution of STMW thicknesses, with a vertical temperature gradient <2.0 °C/100 m occupying the 14–20 °C range below the mixed layer depth, across the entire Southwest Pacific region. STMW changes in areal thickness extent, vertical cross-sectional area along selected transects, and total volume, are examined on seasonal and interannual time scales between 1973 and 1988.We find that STMW extends across the entire width of the Tasman Sea in a very broad swath between the Tropical Convergence in the north (just to the south of New Caledonia), the southeast Australian coast in the west to as far south as 39°S (likely due to the southward extension of the EAC), and eastwards along the Southern STMW boundary in a meandering pathway that broadly follows the Tasman Front. The total STMW volume across the region (i.e., west of 180°) varies seasonally by a factor of more than three between the estimated maximum of 6.6 (±0.5) × 10¹⁴ m³ in October and minimum of 1.9 (±0.4) × 10¹⁴ m³ in May. Interannual variations O (±0.5 × 10¹⁴ m³) are also observed in the spatial extent of the thick mode water and its total volume. El Niño composite maps show an anomalous thickening of the STMW during the El Niño year with October positive thickness anomalies in excess of +20 m (total volume anomaly of +0.6 × 10¹⁴ m³) manifested throughout the subtropical gyre interior as far north as New Caledonia. Total volume anomalies tend to be positive from January of the El Niño year through to the July following (18 months). The maximum correlation coefficient r = −0.3 between 3-monthly STMW volume anomalies and the Southern Oscillation index is statistically significant at the 95% confidence level. We conclude that during the anomalous cooling of the upper Southwest Pacific Ocean in the El Niño year, winter-time convection and STMW formation is enhanced across the region resulting in an El Niño – Southern Oscillation climate signal that is identifiable below the mixed layer by the increased STMW volume which persists through to the following winter. Finally, some evidence for the possible decadal modulation of the STMW variability is also discussed.     

Surface ozone concentrations in Agra: links with the prevailing meteorological parameters

Measurements of surface ozone (O₃), nitric oxide (NO), nitrogen dioxide (NO₂), oxides of nitrogen (NO_x=NO+NO₂) and meteorological parameters have been made at Agra (North Central India, 27°10??N, 78°05??E) in post monsoon and winter season. The diurnal variation in O₃ concentration shows daytime in situ photochemical production with diurnal maximum in noon hours ranging from 51 to 54 ppb in post monsoon and from 76 to 82 ppb in winter, while minimum (16?C24 ppb) during nighttime and early morning hours. Average 8-h O₃ concentration varied from 12.4 to 83.9 ppb. The relationship between meteorological parameters (solar radiation intensity, temperature, relative humidity, wind speed and wind direction) and surface O₃ variability was studied using principal component analysis (PCA), multiple linear regression (MLR) and correlation analysis (CA). PCA and MLR of daily mean O₃ concentrations on meteorological parameters explain up to 80 % of day to day ozone variability. Correlation with meteorology is strongly emphasized on days having strong solar radiation intensity and longer sunshine time.     

Stochastic characterization of earthquakes through their response spectrum

If earthquakes are modelled by a stochastic process, it is possible to interpret the associated response spectrum in terms of the statistics of extreme values of oscillator response to the process. For a stationary earthquake model this interpretation leads to a relationship between the power spectral density function of the process and the response spectrum. This relationship is examined in this paper and forms the basis for two methods presented to obtain the power spectrum of the earthquake process from its response spectrum. One of these methods is approximate but leads to an explicit representation of the power spectral density function in terms of the response spectrum. The other method is exact wherein an iterative scheme for the solution of the problem is established. An example problem is solved to illustrate the use of the two methods and it is shown that for small values of damping, the approximate derivation yields a fairly accurate solution.     

Differences in tree species diversity and soil nutrient status in a tropical sacred forest ecosystem on Niyamgiri hill range, Eastern Ghats, India

We have quantitatively analyzed the tree species diversity with respect to soil nutrient status in three sites of a sacred forest ecosystem of Niyamgiri hill range,Eastern Ghats,India.Extensive field surveys and sampling were conducted in 3 sites of the hill range:Site 1 Pterocarpus dominated forest(PTF)(19°40’02.2" N and 83°21’23.1" E),Site 2 Mangifera dominated forest(MAF)(19°40’02.8" N and 83°21’40.8" E) and Site 3 Mixed forest(MIF)(19°36’47.1" N and 83°21’02.7" E).A total of 28 families,42 genera,46 tree species,and 286 individual trees were recorded on an area of 0.6 ha.Tree density varied between 470 and 490 individuals ha-1 and average basal area between 3.16 and 10.04 m2 ha-1.Shannon Index(H’) ranged from 2.34 to 4.53,Simpson’s Index ranged from 0.07 to 0.09,and equitability Index ranged from 0.7 to 1.34.The number of individuals was highest in the girth at breast height(GBH) class of 50-70 cm.The soil nutrient status of the three forest types was related to tree species diversity.The soil pH value of the three sites reflected the slightly acidic nature of the area.Species diversity was positively correlated with organic carbon and phosphorus and negatively with nitrogen,EC and pH.The results of the current study may be helpful to further develop a conservation planfor tree species in tropical sacred forest ecosystems.     

Solutions to the field equations and the deceleration parameter

We utilise a form for the Hubble parameter to generate a number of solutions to the Einstein field equations with variable cosmological constant and variable gravitational constant. The Hubble law utilised yields a constant value for the deceleration parameter. A variety of solutions is presented in the Robertson-Walker spacetimes. A generalisation of the cosmic scale factor is utilised in the anisotropic Bianchi I spacetime to illustrate that new solutions may also be found in spacetimes with less symmetry than Robertson-Walker. We also show that the constant deceleration parameter used is consistent with alternate theories of gravity by considering the scalar-tensor theory of Lau and Prokhovnik with ak = 0 Robertson-Walker background.     

The vacuum Friedmann-type solutions in Barber's theory of gravitation

Vacuumk=0 Friedmann-type solutions in the continuous creation theory of gravitation proposed by Barber have recently been found by Reddy (1987). Here we obtain thek=±1 Friedmann solutions in Barber's theory. Also, we show that these models are, in fact, vacuum Brans-Dicke solutions that have been studied earlier by Lorenz-Petzold (1984).