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39 pages, 5 figures, 2 tables, More than 50% of the world's total marine catch (approximately 81 million tonnes) is harvested using towed fishing gears (i.e. Danish seines, dredges and otter and beam trawls). As for all methods, the total fishing mortality of these gears comprises the reported (landed) and unreported catch and other unaccounted, collateral deaths due to (i) avoiding, (ii) escaping, (iii) dropping out of the gear during fishing, (iv) discarding from the vessel, (v) ghost fishing of lost gear, (vi) habitat destruction or subsequent (vii) predation and (viii) infection from any of the above. The inherent poor selectivity of many towed gears, combined with their broad spatial deployment, means that there is considerable potential for cumulative effects of (i)-(viii) listed above on total fishing mortality, and subsequent wide-scale negative impacts on stocks of important species. In this paper, we develop a strategy for minimizing this unwanted exploitation by reviewing all the primary literature studies that have estimated collateral, unaccounted fishing mortalities and identifying the key causal factors. We located more than 80 relevant published studies (between 1890 and early 2006) that quantified the mortalities of more than 120 species of escaping (26 papers) or discarded (62 papers) bivalves, cephalopods, crustaceans, echinoderms, elasmobranches, reptiles, teleosts and miscellaneous organisms. Seven of these studies also included the estimates of mortalities caused by dropping out of gears, predation and infection [(iii), (vii) and (viii) listed above]. Owing to several key biological (physiology, size and catch volume and composition), environmental (temperature, hypoxia, sea state and availability of light) and technical (gear design, tow duration and speed) factors, catch-and-escape or catch-and-discarding mechanisms were identified to evoke cumulative negative effects on the health of most organisms. We propose that because the mortalities of discards typically are much greater than escapees, the primary focus of efforts to mitigate unaccounted fishing mortalities should concentrate on the rapid, passive, size and species selection of non-target organisms from the anterior sections of towed gears during fishing. Once maximum selection has been achieved and demonstrated to cause few mortalities, efforts should be made to modify other operational and/or post-capture handling procedures that address the key causal factors listed above. © 2006 Blackwell Publishing Ltd., This study was funded by the New South Wales Department of Primary Industries and the Australian Fisheries Research and Development Corporation (Grant no. 2005/056)

The deepening and maintenance of the world's ports and navigable waterways has been an integral part of the world economy for centuries. In recent years, cutterhead and draghead hydraulic suction dredges have performed a majority of the dredging work. The ongoing design and testing of hydraulic dredges is important for maintaining efficient dredging operations within the limits set by increasing environmental regulations. The high cost of building and operating a hydraulic dredge makes field testing of full-scale prototypes very expensive and time consuming. Moreover, the testing conditions are generally difficult to control, and the natural unpredictability of the sea can render experimental results inconclusive. These factors substantiate the need for laboratory model testing of hydraulic dredging operations. The usefulness of any hydraulic model depends on the degree of geometric, kinematic, and dynamic similarity between the model and its prototype. The primary challenge in establishing useful similitude criteria for model dredge studies is proper kinematic scaling of the suction inlet velocity, average particle settling velocity, dredge swing velocity, and cutter rotational speed. Despite the inherent challenges, model studies of hydraulic dredge equipment have proven useful for obtaining qualitative results. The new Coastal Engineering Laboratory at Texas A&M University is equipped with model dredge testing facilities ideal for performing such experiments. The tow/dredge carriage has a fully adjustable dredge ladder, a 14.9 kW (20 hp) cutter drive, and a 2.54 cm (3 in) dredge pump. A Programmable Logic Controller (PLC) provides computer numerical control and real-time data collection and analysis during model dredging operations. The purpose of this thesis is to investigate scaling relationships for hydraulic dredge model studies and to design a model dredge carriage for the new laboratory facilities recently constructed at the Texas A&M University College Station campus. Pursuant to the design of the new dredge modeling facilities, a rationale for scaling the model dredge operating parameters based on previous model studies is put forward. Examples of model studies that could be performed with the proposed facilities are discussed as well as how the scaling methodology is applied to each experiment to allow the quantitative interpretation of experimental data. http://archive.org/details/laboratorymodeli109453051 Lieutenant, United States Navy Approved for public release; distribution is unlimited.

After dredged sediments have settled in a temporary upland disposal site, ripening starts, which turns waterlogged sediment into aerated soil. Aerobic biological mineralization of organic matter (OM) and chemical oxidation of reduced sulfur compounds are the major biochemical ripening processes. Quantitative data describing these processes are scarce. Therefore, aerobic oxidation and mineralization of five previously anaerobic dredged sediments were studied during a 160-d laboratory incubation experiment at 30 degrees C. A double exponential decay model could adequately describe sulfur oxidation and OM mineralization kinetics. During the first 7 d of incubation, 23 to 80% of the total sulfur was oxidized, after which no further sulfur oxidation was observed. Oxygen used for sulfur oxidation amounted up to 95% of the total oxygen uptake in the first 7 d and up to 45% of the oxygen uptake during the entire incubation period. Mineralization rates of the rapidly mineralizable OM fractions that degraded during the first 14 to 28 d of incubation were 10(2) to 10(3) times higher than the mineralization rates of the slowly mineralizable OM during the remaining period. First-order mineralization rates of the slowly mineralizable OM were 0.22 x 10(-3) to 0.54 x 10(-3) d(-1) and can be compared with those of terrestrial soils. Yields of biomass on substrate ranged from 0.08 to 0.45 g C(biomass)/g C(OM) and appeared to be higher for rapidly mineralizing OM than for slowly mineralizing OM. The results of this study can be used to optimize conditions during temporary disposal of sediments, to estimate the potential decrease in OM, and for future studies on the possible link between OM mineralization and degradation of hydrophobic organic contaminants.

12th International Conference on the Mediterranean Coastal Environment (MEDCOAST), WOS: 000377577200057, Approximately 5x10(6) cubic meter of sediment is removed annually from the harbours, ports, marinas and river mouths in Turkey. Uncontrolled dumping of these dredged materials might create contamination based on the assumption that this material is somehow polluted with the human activity related to the surrounding location. Selection of the disposal sites at sea is one of the important steps of dredge material management process described in most of the international conventions. As part of the ongoing "Dredging Applications and Environmental Management of Dredge Material Project (DIPTAR)" project, the dredged material disposal sites in Turkish Seas were determined by identifying: (i) the areas prohibited to disposal of dredged material, (ii) the coastal areas which have frequent dredging activities, (iii) behaviour of the dumped sediment and the area of impact determined by STFATE Model (Short-Term Fate of Dredged Material Disposal in Open Water), (iv) the scientific criteria which the candidate dumping sites should fulfil. The candidate dumping sites were separated into two main classes according to the dredged material volume (more or less than 100,000 cubic meters). Physical, chemical, and biological characteristics of the water column and the seabed properties were taken into account in determination of the limiting parameters for different seas of Turkey by the expert group. The scientific criteria about water currents (velocity, direction), distance from coastal area, depth, bottom slope, deep water oxygen, Dissolved Inorganic Nitrogen (DIN), Total Phosphate (TP), chlorophyll-a concentrations and Secchi disk depth were established by expert judgement, using scientific information about the oceanographic characteristics of each sea and recent monitoring/research project results. Finally 54 dumping sites were determined on the coastal areas of Turkish seas (Aegean 11, Mediterranean 17, Marmara Sea 9, Black Sea 17 sites) for disposal of small and large volumes of sediments accumulated in the coastal sea by natural physical processes., Mediterranean Coastal Fdn, Inst Oceanol, Inst Fish Resources, Republ Turkey, Promot Fund