The research vessel Palmetto is the largest ship operated by the South Carolina Department of Natural Resources. It is used to monitor offshore marine fisheries in South Carolina, Georgia, North Carolina, and Florida. Grouper and black sea bass are two of the major groups of fish studied by the researchers. The other samples DNR uses include water, bottom, temperature, and pollution samples. Equipment used by the vessel range from traps and hooks and lines to CDT and underwater TV to remotely assess the fish stock. The Palmetto is 112 feet long and 26 feet wide. It carries seven staff members and up to 15 additional scientists for up to 22 days at sea. The 1050-horsepower engine moves the vessel up and down the Atlantic Coast. The captain’s job is to plan the trip, taking into account safety, weather, and navigation. The vessel is in compliance with the Clean Water Act, and does not discharge pollutants into the ocean.
The ocean tells us many things. By monitoring fish populations, including numbers, sizes, rates of growth, ratio of males to females, and maturity levels, scientists can see the direct effects of fishing pressure and provide information for fishing in the future. The method of collecting data is kept consistent so that changes in the populations can be attributed to changes in the environment -- not effects from the study.
CDT is an instrument used on the vessel to measure conductivity or salinity, temperature, and depth. These factors are important to the size of fish populations, and the data collected can be attributed to changes in these variables. Hook-and-line fishing is done to imitate actual fisherman, but the fishermen time their activity so they can calculate a catch per unit of effort ratio. The otolith is an ear stone in fish and is removed in dissection. It has layers that show the age of the fish. More tissue samples are removed to determine the DNA and the place of birth of fish. Eggs in ovaries are observed to determine the time of year of spawn. Some fish are tagged and released. Rewards are given to fishermen who catch these fish and report to DNR. This information reveals migratory patterns and growth rates of the catch.