Fishing dynamics associated with periodically harvested marine closures

Periodically-harvested fisheries closures are emerging as a socially acceptable and locally implementable way to balance concerns about conserving ecosystem function and sustaining livelihoods. Across the Indo-Pacific periodically-harvested closures are commonly employed, yet their contribution towards more sustainable fisheries remains largely untested in the social and ecological context of tropical small-scale fisheries. To address this, we use an interdisciplinary approach to examine harvesting dynamics that would affect sustainability, namely, fishing effort, yield, gear and method use, periodicity of harvesting, controls placed on harvesting and resource owners’ decisions to open and close four fishing grounds in Solomon Islands. We compare these fishing patterns with those on surrounding, continuously open fishing grounds. Our study shows that total effort and total catch from periodically-harvested reef closures are low to moderate compared to reefs open to continuous fishing. When periodically-harvested closures were opened, effort in the closures was relatively intense, however, in most cases yield did not exceed annual benchmarks of sustainability described by previous studies. In some cases, harvesting during openings was restricted to a single taxon and single fishing gear and method, while in others there was unrestricted multi-species and multi-method harvesting. The duration and frequency of openings were highly variable, with open periods ranging from a single night to one month in duration, and occurring between one and 15 times per year. Fishing during openings was permitted for entire fishing communities in some cases, and only for specific rights-holding families in others. Decisions to open periodically-harvested closures tended to be based on immediate social or economic needs, and the openings provided a small boost to fish catch landed in communities. While periodically-harvested closures may alleviate fishing pressure in a small area of fishing grounds by reducing the opportunity to fish, openings of long duration or high frequency, combined with heavy or destructive exploitation, may lead to unsustainable harvesting within the area.     

1988–1991 photometry of the chromospherically active double-lined binary system HD 163621 = V835 Herculis

Photometry inV andB with a 16inch automatic telescope from 1988 to 1991 confirms the synchronous rotation suspected earlier and reveals variability up to 0^M.10 in theB bandpass at one epoch. Five spots formed with lifetimes ranging from 0.15 to 0.77 years. As with other rapid rotators, the differential rotation coefficient (k = 0.03) is significantly smaller than that of the Sun (k = 0.19).     

Low velocity impacts into dust: results from the COLLIDE-2 microgravity experiment

We present the results of the second flight of the Collisions Into Dust Experiment (COLLIDE-2), a space shuttle payload that performs six impact experiments into simulated planetary regolith at speeds between 1 and 100 cm/s. COLLIDE-2 flew on the STS-108 mission in December 2001 following an initial flight in April 1998. The experiment was modified since the first flight to provide higher quality data, and the impact parameters were varied. Spherical quartz projectiles of 1-cm radius were launched into quartz sand and JSC-1 lunar regolith simulant targets 2-cm deep. At impact speeds below ∼20 cm/s the projectile embedded itself in the target material and did not rebound. Some ejecta were produced at ∼10 cm/s. At speeds >25 cm/s the projectile rebounded and significant ejecta was produced. We present coefficients of restitution, ejecta velocities, and limits on ejecta masses. Ejecta velocities are typically less than 10% of the impact velocity, and the fraction of impact kinetic energy partitioned into ejecta kinetic energy is also less than 10%. Taken together with a proposed aerodynamic planetesimal growth mechanism, these results support planetesimal growth at impact speeds above the nominal observed threshold of about 20 cm/s.     

Evaluation of the snow‐covered area data product from MODIS

The Moderate Resolution Imaging Spectroradiometer (MODIS), flown on board the Terra Earth Observing System (EOS) platform launched in December 1999, produces a snow‐covered area (SCA) product. This product is expected to be of better quality than SCA products based on operational satellites (notably GOES and AVHRR), due both to improved spectral resolution and higher spatial resolution of the MODIS instrument. The gridded MODIS SCA product was compared with the SCA product produced and distributed by the National Weather Service National Operational Hydrologic Remote Sensing Center (NOHRSC) for 46 selected days over the Columbia River basin and 32 days over the Missouri River basin during winter and spring of 2000–01. Snow presence or absence was inferred from ground observations of snow depth at 1330 stations in the Missouri River basin and 762 stations in the Columbia River basin, and was compared with the presence/absence classification for the corresponding pixels in the MODIS and NOHRSC SCA products. On average, the MODIS SCA images classified fewer pixels as cloud than NOHRSC, the effect of which was that 15% more of the Columbia basin area could be classified as to presence–absence of snow, while overall there was a statistically insignificant difference over the Missouri basin. Of the pixels classified as cloud free, MODIS misclassified 4% and 5% fewer overall (for the Columbia and Missouri basins respectively) than did the NOHRSC product. When segregated by vegetation cover, forested areas had the greatest differences in fraction of cloud cover reported by the two SCA products, with MODIS classifying 13% and 17% less of the images as cloud for the Missouri and Columbia basins respectively. These differences are particularly important in the Columbia River basin, 39% of which is forested. The ability of MODIS to classify significantly greater amounts of snow in the presence of cloud in more topographically complex, forested, and snow‐dominated areas of these two basins provides valuable information for hydrologic prediction. Copyright © 2003 John Wiley & Sons, Ltd.     

The Square Kilometre Array: An International Engineering Perspective

The pace of the international Square Kilometre Array (SKA) project is accelerating, with major concept reviews recently completed and a number of technology demonstrators well underway. First-round submissions to host the telescope were lodged by six countries. The SKA timeline currently shows a site decision in 2006, and one or more technology concepts chosen in 2008. The telescope is expected to be operational, in various phases, in the period 2015–2020. This paper gives a status review of the project, and outlines engineering concept development and demonstration projects.     

Core Density Profile Survival in Dissipationless Mergers

We use N-body experiments to study the survival of power-law density cusps in mergers of spherical galaxy models. Steep cusps (e.g. ρ∝r ^-2) are preserved during mergers of equal-mass models; this may be viewed as a general consequence of the incomplete violent relaxation observed in such mergers. Progenitor profile has a strong effect on remnant shape; steep cusps produce oblate remnants. If bright ellipticals form by hierarchical mergers of faint ones, the lack of steep cusps in these galaxies is somewhat surprising. This revised version was published online in July 2006 with corrections to the Cover Date.     

Contrasting conditions preceding MIS3 and MIS2 Heinrich events

This paper presents an integrated multi-tracer study performed on piston cores recovered in the glacial ice-rafted detritus belt, stretching from Newfoundland to the Irish margin across the North Atlantic (40–55°N), in order to compare in detail the internal structure of each Heinrich event (HE). These tracers are IRD counts (quartz, dolomite, volcanic grains), their Nd isotopic composition and Ar–Ar datings of individual hornblende grains. A focus on the detailed structure of HE confirms that all intervals of massive sediment flux, specifically Heinrich layers HL1-to-5 (HLs), were dominated by North American, Laurentide ice-sheet surges from Hudson Strait, that are evident as far east as the Bay of Biscay (European margin). The sequences of events leading up to the HLs, however, present significant dissimilarities. One important difference is that HL2 and HL1 were preceded by “precursor events” (increases in the number of lithic grains per gram from non-Laurentide sediment sources). Sediment debris derived from near-simultaneous iceberg releases originating from the European ice-sheet are only detectable close to the European margin. In contrast there are no comparable precursor events before HL5 and HL4. This observation implies that precursor events are unlikely to be mechanistically linked to the triggering of HEs. The similarity of the HLs, against contrasting background conditions, is a significant observation that should add constraints to their origin.     

54 Cam: A new variable star

Differential photometry of the RS CVn-type binary 54 Cam in 1978, 1979, and 1980 shows its light to be variable with a period of 10 _. ^d 163±0 _. ^d 009 and an amplitude inV (max. to min.) which increased from 0 _. ^m 03 to 0 _. ^m 06 between 1979.19 and 1980.82. An epoch of light minimum was JD 2444529.7. The 9% difference betweenP(phtm.)=10 _. ^d 163 andP(orb.)=11 _. ^d 0764,a much larger difference than is characteristic of other RS CVn binaries, is suggested as an explanation for the radio emission.Guest Investigator, Kitt Peak National Observatory,which is operated by the Association of Universities for Research in Astronomy, under contract with the National Science Foundation.Of the AAVSO.     

The use of angles and angular rates

Earlier work on the angles and angular rate initial orbit determination problem has been extended to allow the incorporation of arbitrary amounts and mixtures of angles and angular rate data. The statistical estimation technique used is that of Maximum Likelihood. Numerical tests on six widely different satellite orbits indicate that the orbital elements can generally be computed to 1% from data acquired during a single apparition.This work was sponsored by the Department of the Air Force.