RIASSUNTO
ABSTRACT
A 22-month investigation is being conducted cooperatively by private fishing industry and the U. S. Government to demonstrate the feasibility of using satellite (LANDSAT) data for enhancing the management and utilization of coastal fishery resources in the northern Gulf of Mexico.
Menhaden (Brevoortia patronus) and thread herring (Opisthonema oglinum) were selected as target species in the study areas located in the Mississippi Sound and off the Louisiana coast. Three main data acquisition missions were planned for each test area. The missions included satellite and aircraft remote sensing and in situ sampling of oceanographic parameters from oil platforms and research vessels. Fish school location surveys were conducted from fishing industry spotter aircraft, and in situ oceanographic sampling coincident with fish catches were made by observers aboard the commercial fishing fleet.
Synoptic sea truth data were obtained from surface platforms for correlation with data obtained from remote sensing aircraft and satellites. This investigation is expected to produce a valuable source of information to augment knowledge of the coastal water ecology and provide new remote sensing and data management techniques.
INTRODUCTION
Need
Years of fishing experience have indicated that Gulf menhaden (Brevoortia patronus) respond to certain marine environmental factors. For example along the Gulf Coast these surface schooling fish are genera1ly found in turbid coastal waters and usually close to shore. They are seldom found in freshwater discharge of rivers. Except for these general observations, little is known about the relationship of the distribution of this very important resource with the environment. The subject investigation is designed to explore this relationship, and in particular to determine if satellite remote sensors can be used to locate concentrations of menhaden via the measurement of certain oceanographic parameters.
Another species found in the northern Gulf of Mexico, but not exploited commercially despite its potential value, is the thread herring (Opisthonema oglinum). Also a surface schooling fish, this species was selected as a second target -resource for the investigation in hopes that additional behavioral information might stimulate and help to make feasible extensive commercial fishing of this under-utilized resource.
Problem of Operation
Because fishing areas are so extensive, it is not feasible for surface sampling procedures to provide the comprehensive picture of the marine environment required to evaluate its relationship to resource distribution. .Techniques have been developed recently and are continuing to be developed which allow large area surveys to be made efficiently through the use of aircraft- or satellite-borne sensors. Color measurements of water are made from satellite and aircraft, and from these measurements turbidity can be derived. Sea surface temperature- can be measured from satellite and aircraft accurate to 1.0° and 0.5°C, respectively. Surface water salinity can be measured using airborne microwave sensors. While surface observation and measurement are still necessary to calibrate remotely acquired data, the remote measurement extends the scope of environmental measurements to cover large areas in a short time period.