Cloud tests are used to observe behavioral changes in feeding shark populations. A successful semiochemical repellent diminishes a population of feeding sharks, but does not disturb smaller fish in the area. The objective is to deliver a dose of repellent under pressure, to form a subsurface cloud, which is detected by sharks in the delivery zone. Once detected, the sharks will leave the feeding zone for a measurable amount of time, often, 15 minutes, despite constant chumming..

First, attractant (scent) is established in the test area using chum.

ABOVE: A feeding population is established within a short while, and an initial population count is taken. Sharks are lured closer to the boat with more chum.

ABOVE (2): Grant Johnson with a 4-pack pressurized gun. This gun uses regulated CO2 pressure to push one of four test repellents out towards the feeding sharks, producing a cloud. This design is completely portable, and allows four tests to be conducted relatively quickly.

Spring check valves and small outlet orifices are used so that the fluid exits gently and uniformly, without creating a gas cloud and loud noises.

Dip tubes are attached to the front of each cylinder to provide an extra 4' of reach.

LEFT: A fish head may also be suspended from the end of the delivery system, to bring sharks directly up to the outlet tube of the delivery system. Behavioral controls are established with the same apparatus, in order to demonstrate that sharks are not afraid to feed from the pole, nor are deterred from feeding by pressurized jets of seawater or dyed water controls.

ABOVE: Sometimes, sharks cannot be lured directly up to the boat. When the water depth is within 6', a remotely triggered repellent cylinder is used (a control cylinder holds seawater). These pressurized tubes are actuated with a 12VDC signal, opening a solenoid for the repellent fluid. Fish heads and bait are secured to the rebar post below the waterline. Once sharks work their way up to the rebar and begin tugging on the bait, the solenoid is actuated, and observations are made.

c2001 Shark Defense, Oak Ridge, New Jersey, All rights reserved. Many US Patents Pending.