Spring / Fall Plankton Surveys

See what happened on Leg I and Leg II of the 2003 Fall Plankton Cruise.

Numerous samples are collected during ichthyoplankton cruises for Gulf of Mexico wide estimates of abundance, frequency of occurrence and distribution of the larvae and small juveniles of bluefin tuna, King and Spanish Mackerel, Red Drum, snappers and other fishes.

The types of nets most commonly used to collect the samples are Bongo and Neuston nets. Maintaining a 45 degree wire angle is important while towing the net and is measured frequently during the net tow. The angle of the wire is measured manually and relayed to the bridge so that adjustments to the course and speed can be made accordingly.

Deploying a Bongo net.

Bongo nets suspended from the J-frame.

Using the "frying pan" to measure the angle of the wire.

In addition to the net tow, a CTD (conductivity, temperature and depth) cast is often done while on station. The sensors on the CTD continuously measure conductivity and temperature in the water column. Depth information is provided for each conductivity and temperature reading. Water samples are also collected during the CTD cast for analysis on board ship.

A scientist collects a water sample from the CTD.

Oceanographic operations are monitored in the dry lab. The data is recorded on the shipboard computer system.

Monitoring operations in the dry lab.