Composite Training Unit Exercises and Joint Task ... - Govsupport.us

COMPTUEX/JTFEX EA/OEA Final Chapter 4Culik et al., (2001) indicated the mid- frequency sound from acoustic devices designed to deter marinemammals from gillnet fisheries were either inaudible to fish or, the fish were not disturbed by the sound.Based on the evaluation of the data presented below, significant effects on fish are not anticipated fromthe use of mid-frequency active sonar.4.3.1.3.1 Underwater DetonationsWith respect to underwater detonations, several factors determine a fish’s susceptibility to harm. Mostinjuries in fish involve damage to air- or gas-containing organs. Some commercially significant speciesof fish have swim bladders, which are gas-filled organs used to control buoyancy. Fish with swimbladders are vulnerable to effects of explosives, while fish without swim bladders are much more resistant(Yelverton, 1981; Young, 1991). Most fish that die do so within one to four hours, and almost all do sowithin 24 hours (Yelverton, 1973 and 1981).The effects on fish from a given amount of explosive depend on location, season, and many other factors.O’Keeffe (1984) provides charts which allow estimation of the potential effect on swim-bladder fishusing a damage prediction method developed by Goertner (1982). O’Keeffe’s parameters include the sizeof the fish and its location relative to the explosive source, but are independent of environmentalconditions (e.g., depth of fish, explosive shot frequency content). Table 4.3-1 lists the estimatedmaximum effects ranges using O’Keefe’s (1984) method for an 8-lb explosion at source depths of 10 ft (3m).Table 4.3-1. Maximum Fish-Effects RangesFish Weight10% Mortality Rangemft1 oz 157.9 518.31 pound 63.6 208.930 pound 47.3 155.2Source: O’Keefe, 19844.3.1.3.2 ShockwaveSome COMPTUEX/JTFEX operations involve the use of mines, bombs, munitions, missiles, or targetsthat fall into the waters. As described, in many cases, inert ordnance is used, or the ordnance is targetedto explode on a target or hull, substantially reducing the introduction of sound in the surrounding marineenvironment.Where underwater detonation is required for the activity, impacts to the water surface involve force andproduce a shock wave. Larger detonations could injure or kill fish in the immediate vicinity.Several factors determine a fish’s susceptibility to injury and death from shock wave effects. Most blastinjuries in fish and other marine animals involve damage to air- or gas-containing organs (Yelverton,1981). Many species of fish have a swim bladder, which is a gas-filled organ used to control buoyancy.Fish with swim bladders are vulnerable to effects of underwater explosions, whereas fish without swimbladders, like most species of invertebrates, are much more resistant (Yelverton, 1981; Young, 1991).During exposure to shock waves, the differential speed of shock waves through the body of the fish(which has a density close to water) versus the gas-filled space of the swim bladder causes the bladder tooscillate. If the swim bladder ruptures, it may cause hemorrhages in nearby organs. In the extreme case,the oscillating swim bladder may rupture the body wall of the fish (Yelverton, 1981). Some fish have aswim bladder that is ducted to the intestinal tract and some do not, but there is no difference in4-13 February 2007