Student Connection

Just in from the Ship

TC-99-11 Swordfish Larvae
November 09 - November 15, 1999

November 15, 1999  We are underway again. This week the NOAA Ship Townsend Cromwell is studying the plankton and juvenile fish near the west coast of the Island of Hawaii. The local folks call this "The Big Island" because it is the largest of the Hawaiian Islands. We are all happy to be working here because the weather is very nice and the waves are small. The trade winds usually blow steadily from the east across the Islands. Since wind makes waves, the east side of the Island has rougher water and the west side is sheltered from the wind and the sea is gentle and smooth. Sailors call this shelter a "lee". We are in the lee of the Big Island. We like it. We are using two types of net to catch the plankton and young fish. The Isaacs - Kidd trawl net is a pretty large net made for catching small fish. The IK is named after two scientists that invented it. We are towing it on the surface of the water because fish larvae and juveniles like to hang out there. The second kind of net is the "MOCNESS". The strange name comes from the abbreviation for: Multiple Opening and Closing Net, Environmental Sensing System. Try saying that three times fast. It has 9 different nets that can be opened one at a time. That way you can get an idea of what organisms live at different depths.

We are also doing CTDs. If you are a regular reader, you know that CTD stands for Conductivity, Temperature, and Depth. Our CTD also has a chlorophyll sensor and an oxygen sensor attached so researchers can look at how these measurements change as it is lowered down into the water.

One of the researchers on board is using sound waves to look for concentrations of prey for dolphins. We lower a small fish finder over the side and record the sound waves that bounce off of the fish and are reflected back to the ship. This may help to learn how many of the kinds of fish are here that dolphins eat. Scientists like to think about things like why lots of little fish can be found in one place rather than another. Sometimes knowing the temperature or amount of chlorophyll that is there helps to explain these things.

Last modified December 07, 1999