ALBERT

Beschreibung: This document, which is directed at the fishing sector, researchers, conservationists and fishery administrators, was developed by researchers who are members of the Specialists Group for Marine Turtle Research and conservation in the Southwestern Atlantic Ocean (SWA) in response to the urgent need to evaluate the impact generated on sea turtles by fisheries. Historically, sea turtle conservation efforts have focused almost exclusively on the protection of nesting beaches. Nevertheless, over the last decade, research has proved incidental mortality as a result of fishing activities to be one of the greatest threats to these animals. This type of interaction is not only problematic for turtles, but also generates financial losses for fishermen and businesses. In spite of the efforts that are currently underway, researchers still do not have a detailed understanding of the impact that bycatch produces on sea turtle populations in the SWA. We have a long way to go before its effects can be minimized. Further research is needed regarding the biology and ecology of the various turtle species as well as the effective application of mitigation measures. The life cycles of sea turtles are long and complex. Turtles occupy various ecosystems (nesting beaches, coastal, neritic and oceanic zones, as well as pelagic and demersal areas) throughout their lifetimes, transcending various Exclusive Economic Zones and International Waters. The five species that inhabit the SWA region perform vast feeding and reproductive migrations, traveling through areas where many different fishing fleets operate. Therefore, sea turtles in the SWA interact with virtually all fisheries. These circumstances make it necessary to carry out biological, fishing related and conservation studies on a regional level. The efficiency of the existing international and national legal instruments has yet to be determined, in terms of their effectiveness in protecting sea turtles. In some cases, legislation that is specifically related to the interaction between fisheries and turtles does exist, such as those laws requiring the mandatory use of turtle excluding devices (TEDs). There are also explicit bans on sea turtle capture. Nevertheless, none of these regulations prevent sea turtle bycatch. Although some regional legal instruments are needed, these and the existing legislation will only be effective if they are accompanied by a broader range of permanent education and control measures, to achieve the commitment of all the parties involved. The ecosystem approach is gaining popularity among fishery administration organizations. Research and conservation efforts should also be moving in that direction. A regional and international effort is required in order to compile information regarding the bycatch produced by the various types of fisheries and fleets operating in the area. The enormous increase in fishing pressure that these fleets are exerting in this area has not been accompanied by an increase in information regarding the bycatch of species that have no commercial value. Pelagic longlining is one of the fishing methods, which must be most closely monitored, due to the high levels of bycatch that it produces, as well its ample distribution throughout the region, and the high level of fishing effort that it accounts for. Coastal trawlers and gillnetters must also be considered critical players, because they too produce a large rate of bycatch. These are the three types of fisheries that are most broadly distributed throughout the region, accounting for the majority of the fishing effort. Most of the institutions that work toward sea turtle conservation in the area have only begun to address the issue of bycatch over the last decade. This timeframe is reflected in the scope and quantity of the available publications, as well as the progress of activities directed at mitigating this problem. All of the institutions that have been mentioned in this report have made the gathering of information regarding interaction between sea turtles and fisheries one of their top priorities. Some institutions are even developing working programs for monitoring fisheries and testing mitigation measures. Many of these institutions have managed to develop adequate relationships with fishermen, ship owners and administrators. Nevertheless, limited access to funding is an obstacle to the development and testing of mitigation measures. The SWA network, which is a very valuable instrument that was created in 2003, has allowed the region’s institutions and researchers to exchange information and share their experience, in addition to lending each other support in carrying out joint activities, thus strengthening sea turtle conservation efforts. The capacity demonstrated so far by the region’s researchers and institutions, testifies to their ability to continue to make progress in knowledge generation and tests of bycatch mitigation measures.

Beschreibung: Published

Beschreibung: Este documento, dirigido al sector pesquero, investigadores, conservacionistas y administradores de las pesquerías, surge como respuesta de investigadores pertenecientes al Grupo de Especialistas en Investigación y Conservación de Tortugas Marinas en el Atlántico Sud Occidental (ASO) a la urgente necesidad de evaluar el impacto de las pesquerías sobre las tortugas marinas. Históricamente, los esfuerzos referidos a la conservación de las tortugas marinas se han dirigido casi exclusivamente a proteger las playas de anidación. Sin embargo en la última década se ha podido comprobar que una de las mayores amenazas es la mortalidad incidental causada por las pesquerías. Esta interacción no implica únicamente un problema para las tortugas, sino que también genera pérdidas económicas para los pescadores y las empresas.

Beschreibung: This document, which is directed at the fishing sector, researchers, conservationists and fishery administrators, was developed by researchers who are members of the Specialists Group for Marine Turtle Research and Conservation in the Southwestern Atlantic Ocean (SWA) in response to the urgent need to evaluate the impact generated on sea turtles by fisheries. Historically, sea turtle conservation efforts have focused almost exclusively on the protection of nesting beaches. Nevertheless, over the last decade, research has proved incidental mortality as a result of fishing activities to be one of the greatest threats to these animals. This type of interaction is not only problematic for turtles, but also generates financial losses for fishermen and businesses.

Beschreibung: Cont. fotografías

Beschreibung: Published

Beschreibung: Sea Turtle, keeping

Beschreibung: Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution February 2007

Beschreibung: Oceanic spreading centers are sites of magmatic, tectonic, and hydrothermal processes. In this thesis I present experimental and seismological constraints on the evolution of these complex regions of focused crustal accretion and extension. Experimental results from drained, triaxial deformation experiments on partially molten olivine reveal that melt extraction rates are linearly dependent on effective mean stress when the effective mean stress is low and non-linearly dependent on effective mean stress when it is high. Microearthquakes recorded above an inferred magma reservoir along the TAG segment of the Mid-Atlantic Ridge delineate for the first time the arcuate, subsurface structure of a long-lived, active detachment fault. This fault penetrates the entire oceanic crust and forms the high-permeability pathway necessary to sustain long-lived, high-temperature hydrothermal venting in this region. Long-lived detachment faulting exhumes lower crustal and mantle rocks. Residual stresses generated by thermal expansion anisotropy and mismatch in the uplifting, cooling rock trigger grain boundary microfractures if stress intensities at the tips of naturally occurring flaws exceed a critical stress intensity factor. Experimental results coupled with geomechanical models indicate that pervasive grain boundary cracking occurs in mantle peridotite when it is uplifted to within 4 km of the seafloor. Whereas faults provide the high-permeability pathways necessary to sustain high-temperature fluid circulation, grain boundary cracks form the interconnected network required for pervasive alteration of the oceanic lithosphere. This thesis provides fundamental constraints on the rheology, evolution, and alteration of the lithosphere at oceanic spreading centers.

Beschreibung: Research was funded by a MIT Presidential Fellowship and NSF grants OCE-0095936, OCE-9907224, OCE-0137329, OCE-6892222, and OCE-6897400.

Beschreibung: Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution December 1997

Beschreibung: A new tomographic technique is employed to investigate the structure and dynamics of the Pacific upper mantle. We invert band-center travel times of ScS reverberations and frequency-dependent travel times of direct S phases, upper-mantle guided waves such as SS and SSS, and the R1 and G1 surface waves for the 2D composite structure in the plane of two Pacific corridors. The frequency-dependent travel times of the turning and surface waves are measured from all three components of ground motion as phase delays relative to a radially-anisotropic, spherically-symmetric oceanic mantle model, and their 2D Fréchet kernels are constructed by a coupled-mode algorithm. The travel times of the primary ScSn and sScSn phases and their first-order reverberations from the 410 and 660 discontinuities are measured as individual phases and the 2D Fréchet kernels for these band-limited signals are calculated using the paraxial ray approximation. The model parameters include shear-speed variations throughout the mantle, perturbations to radial shear-wave anisotropy in the uppermost mantle, and the topography of the 410 and 660 discontinuities. We construct vertical tomograms through two mantle corridors: one between the Tonga subduction zone and Oahu, Hawaii, which traverses the central Pacific Ocean; and the other between the Ryukyu subduction zone and Oahu, which samples the northern Philippine Sea, the western Pacific, and the entire Hawaiian swell. Tests demonstrate that the data sets for the two corridors resolve the lateral structure in the upper mantle with a scale length of a few hundreds kilometers and greater but that the resolving power decreases rapidly in the lower mantle. The model for the Tonga-Hawaii corridor reveals several interesting features, the most significant being a regular pattern of high and low shear velocities in the upper mantle between Tonga and Hawaii. These variations, which are well resolved by the data set, have a horizontal wavelength of 1500 km, a vertical dimension of 700 km, and an amplitude of about 3%, and they show a strong positive correlation with seafloor topography and geoid-height variations along this corridor. The geoid highs correspond to a series of northwest-trending swells associated with the major hotspots of the Society, Marquesas, and Hawaiian Islands. Where these swells cross the corridor, they are underlain by high shear velocities throughout the uppermost mantle, so it is unlikely that their topography is supported by thermal buoyancy. This result is substantiated by the model from the Ryukyu-Hawaii corridor, which exhibits a prominent, fast region that extends beneath the entire Hawaiian swell. This anomaly, which resides in the uppermost 200-300 km of the mantle, is also positively correlated with the undulations of the Hawaiian-swell height. The other dominant features in the Ryukyu-Hawaii model include the high-velocity subducting slabs beneath the Ryukyu and Izu-Bonin seismic zones, which extend throughout the entire upper mantle; a very low-velocity in the uppermost 160 km of the mantle beneath the northern Philippine Sea, which is ascribed to the presence of extra water in this region; and a pronounced minimum in the amount of radial anisotropy near Hawaii, which is also seen along the Tonga-Hawaii corridor. A joint inversion of the data from the two corridors reveals the same anomaly pattern and clearly demonstrates that the swells in the Central Pacific are underlain by fast velocities. It is therefore implied that the topography of the swells in the central Pacific is supported by a chemical buoyancy mechanism which is generated by basaltic volcanism and the formation of its low-density peridotitic residuum. While the basaltic depletion mechanism can produce high shear velocities in the uppermost 200 km, it cannot explain the depth extent of the fast anomalies beneath the swells which, along Tonga-Hawaii corridor, extend well into the transition zone. It is therefore hypothesized that the central Pacific is underlain by a system of convective rolls that are confined above the 660-km discontinuity. It is likely that these rolls are predominantly oriented in the direction of plate motion (like "Richter rolls ") but the limited depth of the fast anomaly beneath the Hawaiian swell (200-300 km) suggests that their pattern is probably more complicated. Nevertheless, this convection pattern appears to be strongly correlated with the locations of the Tahitian, Marquesan, and Hawaiian hotspots, which raises interesting questions for Morgan's hypothesis that these hotspots are the surface manifestations of deep-mantle plumes.

Beschreibung: This research was supported by the National Science Foundation under grant EAR- 9628351 and by the Defense Special Weapons Agency under grant DSW A-F49620-95-1- 0051.

Beschreibung: Submitted in partial fulfillment of the requirements of the degree of Master of Science at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution June 2004

Beschreibung: Laterally extensive, well-developed clinoforms have been mapped in Early Cretaceous deposits located in the northeastern 27,000 km2 of the Colvile Basin, North Slope of Alaska. Using public domain 2-D seismic data, well logs, core photographs, and grain size data, depositional geometries within the Nanushuk and Torok formations were interpreted in order to constrain the transport conditions associated with progradation of the shoreline and construction of the continental margin out of detritus shed from the ancestral Brooks Range. Using STRATA, a synthetic stratigraphic modeling package, constructional clinoform geometries similar to those preserved in the North Slope clinoform volume (32,400 km3) were simulated. Sediment flux, marine and nonmarine diffusivities, and basin subsidence were systematically varied until a match was found for the foreset and topset slopes, as well as progradation rates over a 6 milion year period. The ability of STRATA to match the seismically interpreted geometries allows us to constrain measures of possible water and sediment discharges consistent with the observed development of the Early Cretaceous c1inoform suite. Simulations indicate that, in order to reproduce observed geometries and trends using constant input parameters, the subsidence rate must be very small, only a fraction of the most likely rate calculated from the seismic data. Constant sediment transport parameters can successfully describe the evolution of the prograding margin only in the absence of tectonic subsidence. However, further work is needed to constrain the absolute magnitude of these values and determine a unique solution for the NPR-A clinoforms.

Beschreibung: Seychelles is composed of over 100 islands with a land area of approximately 455 km², centred close to 4°30'S and 55°30'E. The combined coastline is approximately 600 km long, the oceanic shelf totals about 50 000 km² and the Exclusive Economic Zone (EEZ) is over 1 370 000 km². The total population (1994 census) stands at just under 74 000. in 1994, the population registered a growth rate of 2.2%. The GDP (1994) was SR 2373.8 million, fisheries representing 4.8% of this sum. Licensing agreements for foreign fishing activities provided a yearly revenue of SR8 million. Port Victoria is seen as a prime centre for tuna fishing operations in the Indian Ocean. In the artisanal fishery just under 900 persons are working. The largest contributor to catch by vessel type are the traditional whaler vessels representing 47.8% of the total catch. Over 66.3% of the catch is by the handline method. Carangidae representing 24% and Lutjanidae 19% of total landings. There are six specific objectives to the fisheries sector policy, which aims as resource development and maximisation of potential benefits. Nearshore fishery resources are considered to be heavily exploited, however opportunities exist around the distant islands and in deeper waters off the Mahe plateau shelf. Aquaculture of molluscs and prawns is being developed and carried out. The main constraints to development are seen as the lack of skilled manpower and foreign exchange.

Beschreibung: Published

Beschreibung: This journal is published by the NIOF, Egypt

Beschreibung: Lake Manzalah; the largest delta Lake in Egypt represents a dynamic system that has been undergoing continuous and pronounced changes since long times. In the last year’s this Lake faced drastic problems that retarded its environmental and fisheries development; the most serious one is the discharge of waste water. It is attempted in the present study to investigate the chemical characters of Lake Manzalah water during 2001-2002. Water temperature ranged from an average of 12.35oC in January and 29.14oC in July. Dissolved Oxygen, pH and total dissolved solids were found in ranges optimum for the living of marine and freshwater fish species. The average concentrations of nutrients lied in the following ranges: 1.24 to 4.89 μmol PO4 -3 l-1 , 5.08 to 28.73 μmol SiO4 -2 l-1 and 1.81 to 17.7 μ_mol NO3-1 l-1 The concentrations of phosphorus and nitrogen compounds were found to be relatively higher at the southern regions of the Lake near to the outlets of the drains.

Beschreibung: NIOF

Beschreibung: Published

Beschreibung: The present report reviews the spiny lobster fishery on the Mahe Plateau for the 2001/2002 fishing season. The monitoring programme, set up in 1992, was continued this season to collect more information on the spiny lobster stock in order to improve and maintain proper management of this resource around the Mahe Plateau. For the 2001/2002 lobster fishing season, a total of 40 licenses were issued namely twenty seven on Mahe, five on Praslin and eight on La Digue. Similar to previous seasons, the most frequently used lobster fishing technique was snorkelling which involved 32 fishing units, whilst only four units used the trap method and one used both snorkelling and trap. For this three-month fishing season, a total of 5.5 tonnes of spiny lobsters were estimated to have been landed compared to 10.2 tonnes in 2000-2001 fishing season. Most landings were on Mahe, which accounted for 58.44 % of the total catch (3.214 tonnes) followed by Praslin with 13.89% (0.77 tonnes). Both La Digue and Silhouette groups had landings of 0.5 tonnes each. The month of November accounted for 1.36 tonnes, while 3.37 tonnes was landed in December and 0.81 tonnes in January. A total of 350 trips were undertaken equivalent to 803 man-trips for the season with 107 trips in November, 193 trips in December and 50 trips in January. The snorkelling and trap capture methods represented 96% and 4% of the total catch respectively. The catch rates represented by catch per unit effort(CPUE) throughout the season were as follows: - 12.75 kg/trip(November) - 17.49 kg/trip (December) - 16.35 kg/trip January). The main species targeted were: Homard Grosse Tete (Panuliruspenidilatus) Homard Rouge (Panulirus longipes) Homard Vert (Panulirus versicolor). The catch composition by fishing method was as follows: a.) Snorkelling: b.)Trap: Homard Grosse Tete: 65.68% Homard Grosse Tete: 14.21% Homard Rouge: 26.83% Homard Rouge: 85.79% Homard Vert: 7.07%

Beschreibung: Published

Beschreibung: Published

Beschreibung: Industrial tuna fishing

Beschreibung: Fishing performances of four different types of boats (pirogues, outboard, whalers, schooners) are studied through the analysis of the temporal evolution, between July 1985 and June 1988, for four parameters: numbers of active fishing boats,- total number of fishing trips, - average number of trips/boat, - average trip duration. The trends from these analysis reveals that the boats involved in the handline fishery in seychelles have evolved considerably. These changes must be taken into consideration in the case of an eventual reorganisation of the fleet.

Beschreibung: Published

Beschreibung: Published

Beschreibung: Contents: Preface 1. Introduction 2. Linear Regression 3. Discretizing Continuous Inverse Problems 4. Rank Deficiency and Ill-Conditioning 5. Tikhonov Regularization 6. Iterative Methods 7. Other Regularization Techniques 8. Fourier Techniques 9. Nonlinear Regression 10. Nonlinear Inverse Problems 11. Bayesian Methods Appendix A: Review of Linear Algebra Appendix B: Review of Probability and Statistics Appendix C: Glossary of Notation; Bibliography; Index It is accompanied by a Web site that contains Matlab code corresponding to all examples. Audience: Students and professionals in Astrophysics, Applied Mathematics, Atmospheric Science, Geologiocal Engineering, Geophysics, Hydrology, Oceanography and related fields.