ALBERT

Description: (1). During 2003 a total of 3,852 Metric Tonnes (MT) of fish was landed on Mahe, Praslin and La Digue by 405 fishing boats. 80.5% of the total catch was landed on Mahe alone. The total artisanal catch decreased by 1063 (MT) compared to 2002, whilst the number of boats operating increased by 31 over the same period (excluding sport fishing vessels). (2). The most important species groups landed (greater than 5% of the total catch) were carangues (33.6%), job (15.8%), bourgeois (9.1%), cordonier (6.6%), capitaine (6.1%), becune (6.0%), and maquereau doux (5.4%). Compared to 2002, there were notable increases in the relative importance of cordonier and bourgeois to the overall catch. (3). Peak landings occurred in November (463.7 MT) and the lowest catch was recorded in September (137.3 MT). The average monthly catch in 2003 was 321 (MT). (4). Slight seasonal variation in total catch was observed in 2003. The mean monthly catch during the months of May — October, inclusive; was 290.5 MT, compared to a mean montly catch of 318.1 MT during the months of December — March, inclusive. In contrast to the patterns observed in 2001 and 2002, the highest catches for carangues occurred in November rather than April. Catches of cordonnier continued to increase (254.7 MT) over the previous two years, with peak monthly catches coinciding with the peak spawning months for those species, namely October to December. (5). The percentage of the total artisanal catch taken by the small boat fishery (pirogues and outboards) was 28.3%, similar to the estimate obtained in 2002. Fishermen on foot landed 0.6% of the total artisanal catch, with octopus catches from this fishery totaling 21.3 MT in 2003. 5.4 MT of maquereau were landed by pirogues using beach seines. Carangues (22.6%) replaced maquereau doux (19.2%) as the most important species landed by vessels with outboards in 2003, other important groups in this fishery including cordonier (22.3%) and other trap fish (11.9%). In 2003, landings by the small boats and foot fishermen were divided equally between pelagic and semi-pelagic species (48.2%) and demersal/ reef species (51.8%). (6). Typical of previous years, the whaler handline fishery dominated artisanal fisheries catches, accounting for 63.4% of total landings in 2003. An average of 96 whalers operated each month during 2003, an increase of 5 vessels compared to 2002. Carangues made up 42.1% of the total whaler handline catch. Other important species in the catch were, in order of importance, job gris (22.1%), becune (8.3%) bourgeois (8.3%) and bonite (3.7%). For the second consecutive year, catches of bourgeois by the whaler handline fishery increased, by 22.2% over 2002. (7). A maximum of 16 schooners were in operation during 2002 and these vessels accounted for 6.8% of total landings. Bourgeois was again the most important species caught (36.9%), followed by the 'others' category (18.6%) and job gris (8.5%). The spanner crab Ranina ranina accounted for 5.8% of schooner landings. (8). Fish purchases from the artisanal fisheries by Oceana Fisheries Co. Ltd. were equivalent to 10.4% total landings (400.7 MT). Major species groups purchased were red snappers and bourgeois (219 MT), job (57.4 MT), groupers (30,6 MT), capitaine (23.2 MT), octopus (21.9 MT) and carangue (17 MT). (9). Fish purchases from foreign longline and purse seine vessels by Oceana Fisheries Co. Ltd. were 245.9 MT during 2002. Species purchased were all pelagic, of which bonito bait was the most common (112.8 MT), followed by yellowfin (40.3 MT), dorade (37.3 MT) and skipjack (14.1 MT). (10). Fish exports by Oceana Fisheries Co. Ltd. amounted to 201.1 MT, a decrease of around 25 MT compared to 2002. These exports were valued at SR 5.6 million (C.I.F). Compared to the previous year, the markets shifted in order of importance in 2003, with Mauritius constituting the major importer of Seychelles fish products (69.9 MT), followed by Reunion (55.6 MT), England (50.1 MT) and France (14.6 MT). Pelagic fishes (33.8%), bourgeois (29.5%) and job (15.8%) were the most important fish groups exported. (11). A comparison of data collected between 1991 and 2003 follows, The proportion of catch by boat type and number of boats operating shown in the following table does not include the research vessel (RJV L'Amitie) of the Seychelles Fishing Authority, which landed 3.1 MT of fish in 2003, contributing 0.1% to the total artisanal catch.

Description: Published

Description: (1). During 2002 an estimated total of 4915 tonnes of fish was landed on Mahe, Praslin and La Digue by 374 fishing boats. 83.1% of the total catch was landed on Mahe alone. The total catch increased by 625 tonnes compared to 2001, and the number of boats operating decreased by 3 over the same period. (2). The most important species groups landed (greater than 5% of the total catch) were carangues (41.5%), job (12.4%), capitaine (6.8%), becune (6.1%), maquereau doux (5.7%) and bourgeois (5.7%). (3). Peak landings occurred in October (576.5 MT) and the lowest catch was recorded in January (222.51 MT). The average catch per month was 409.6 tonnes. (4). Seasonal variation in catches of demersal species was less marked compared to previous years. The mean monthly catch during the SE Trades (May — October, inclusive) was 420.5 MT, compared to a mean monthly catch of 359.4 MT during the NW monsoon (December — March, inclusive). High catches were probably maintained during the period of May to October in 2002 due to the comparatively weak strength of the SE Trades in that year, as determined by lower than average wind speeds for most months in that period (Meteorological Office, pers. comm.). Identical to the pattern observed in 2001, the highest catches for carangues occurred in April. Catches of cordonnier in 2002 (203.0 MT) were more than double those recorded in 2001 (90.5), and were lowest during the period of March to June, inclusive. (5). In total, the small boat fishery accounted for 26.4% of fish landings during 2002. Compared to the total artisanal catch, the percentage catch by boat type for the small boat fishery was as follows: fishermen on foot — 0.6%; pirogues — 0.6%; outboards -25.2% and whalers with traps — 2.2%. Fishermen on foot mostly landed octopus (87.0%), although cordonnier catches by this category were also recorded in 2002 (12.6%). Due to changes in fisheries fieldworker coverage in 2002, landings of maquereau by pirogue were not recorded, with cordonnier (57.6%) and other trap fish (23.2%) dominating landings instead. The predominant species groups landed by outboards were, in order of importance, maquereau doux (22.6%), carangues (21.7%), other trap fish (13.9%) and cordonnier (13.6%). Whalers with traps landed mainly capitaine (61.3%), other trap fish (20.1%) and cordonnier (12.3%). In 2002, landings by the small boat fleet were once again approximately divided equally between pelagic (51.3%) and demersal/ reef species (47.4%). (6). The whaler handline fishery accounted for 67.9% of total landings. An average of 91 whalers operated each month during 2002, indicating an increase of 1 vessel operating when compared to 2001. Carangues made up 52.5% of the total whaler handline catch. Other important species in the catch were, in order of importance, job gris (16.4%), becune (8.4%) bourgeois (5.0%), bordemar (2.6%) and vara vara (2.2%). Catches of Bourgeois decreased by 28.8% in 2002 compared to the catch of 2001. (7). Purchases from the artisanal fisheries by Oceana Fisheries were equivalent to 10.3% of total landings (504.2 MT). Oceana Fisheries purchased all fish from the Port Victoria site. Major species groups purchased were red snappers and bourgeois (57.5%), job (12.7%), groupers (5.2%) and capitaine (5.9 %). (8). Fish purchases from foreign longline vessels were in the order of 152.3 MT of frozen fish (gutted and ungutted) during 2002. Species purchased were all pelagic, of which bonito bait was the most common (98.0 MT), followed by yellowfin (18.9 MT), dorade (12.6 MT) and skipjack (12.6 MT). (9). Fish exports by Oceana Fisheries amounted to 226.6 MT, 85.9% of which was fresh and 14.1% frozen. These exports were valued at SR 7.1 million (CIF). Major destinations for the fish were England (34.5%), Reunion (30.3%) and Mauritius (17.0%). Pelagic fish (41.5%), bourgeois (23.4%), and Job (19.2%). formed the most important fish groups exported. (10). A comparison of data collected between 1990 and 2002 follows. The proportion of catch by boat type and number of boats operating shown in the following table do not include the research vessels of the Seychelles Fishing Authority which landed 11.7 tonnes of fish in 2002, contributing 0.2% of the total catch.

Description: Published

Description: Following the breakup of the Space Shuttle Columbia during reentry a NASA/Contractor investigation team was formed to examine the probable damage inflicted on Orbiter Thermal Protection System elements by impact of External Tank insulating foam projectiles. The authors formed a working subgroup within the larger team to apply the Smooth Particle Hydrodynamics code SPHC to the damage estimation problem. Numerical models of the Orbiter's tiles and of the Tank's foam were constructed and used as inputs into the code. Material properties needed to properly model the tiles and foam were obtained from other working subgroups who performed tests on these items for this purpose. Two- and three-dimensional models of the tiles were constructed, including the glass outer layer, the main body of LI-900 insulation, the densified lower layer of LI-900, the Nomex felt mounting layer, and the Aluminum 2024 vehicle skin. A model for the BX-250 foam including porous compression, elastic rebound, and surface erosion was developed. Code results for the tile damage and foam behavior were extensively validated through comparison with Southwest Research Institute foam-on-tile impact experiments carried out in 1999. These tests involved small projectiles striking individual tiles and small tile arrays. Following code and model validation we simulated impacts of larger foam projectiles on the examples of tile systems used on the Orbiter. Results for impacts on the main landing gear door are presented in this paper, including effects of impacts at several angles, and of rapidly rotating projectiles. General results suggest that foam impacts on tiles at about 500 mph could cause appreciable damage if the impact angle is greater than about 20 degrees. Some variations of the foam properties, such as increased brittleness or increased density could increase damage in some cases. Rotation up to 17 rps failed to increase the damage for the two cases considered. This does not rule out other cases in which the rotational energy might lead to an increase in tile damage, but suggests that in most cases rotation will not be an important factor.

Description: This report compares seven double-plate penetration predictor equations for accuracy and effectiveness of a shield design. Three of the seven are the Johnson Space Center original, modified, and new Cour-Palais equations. The other four are the Nysmith, Lundeberg-Stern-Bristow, Burch, and Wilkinson equations. These equations, except the Wilkinson equation, were derived from test results, with the velocities ranging up to 8 km/sec. Spreadsheet software calculated the projectile diameters for various velocities for the different equations. The results were plotted on projectile diameter versus velocity graphs for the expected orbital debris impact velocities ranging from 2 to 15 km/sec. The new Cour-Palais double-plate penetration equation was compared to the modified Cour-Palais single-plate penetration equation. Then the predictions from each of the seven double-plate penetration equations were compared to each other for a chosen shield design. Finally, these results from the equations were compared with test results performed at the NASA Marshall Space Flight Center. Because the different equations predict a wide range of projectile diameters at any given velocity, it is very difficult to choose the "right" prediction equation for shield configurations other than those exactly used in the equations' development. Although developed for various materials, the penetration equations alone cannot be relied upon to accurately predict the effectiveness of a shield without using hypervelocity impact tests to verify the design.