RIASSUNTO
ABSTRACT
The first international, long-term, cold water saturation scientific diving program was conducted from September through November 1975 in 110 feet of water, 10 miles off Rockport, Massachusetts. The program was coordinated by the National Oceanic and Atmospheric Administration using the West German Underwater Laboratory ""Helgoland."" Over sixty participants, diver scientists, and technologists and support personnel from the United States, West Germany, Soviet Union, and Poland included three, four-man teams of scientists who completed 164 mandays of saturation bottom time. They completed an ecological study of a herring spawning site, studied fish behavior and trapping methods, and initially tested a hydroacoustic calibration system.
INTRODUCTION
The National Oceanic and Atmospheric Administration (NOAA) has been conducting a number of long term research programs concerning herring and other pelagic fishes in the Gulf of Maine and Georgers Bank areas off New England. The studies have involved the use of man-in-the-sea techniques including the use of research submersibles and scuba diving from trawlers as well as ship based hydroacoustic and dredging studies. A number of the research efforts have been under the auspices of the International Commission of Northwest Atlantic Fisheries (ICNAF), an association of 18 countries which establishes catch quotas for various fish species in the area.
Of particular importance to the commercial fisheries in the Northwest Atlantic is the herring (clupea harengus harengus L.). Herring is used for human and pet food, as well as in other products such as lobster bait, pearl essence, and oil extract. Annual landing by U.S. and foreign fishermen in the last few years have exceeded one billion pounds--the largest biomass of any single species in the New England region. United States fisherman have historically concentrated on juvenile herring, marketed in the U.S. as ""sardines, "" while other nations concentrated on adults. This trend is now changing and U.S. fisherman also depend upon the adult. The degree to which either of these fisheries may affect the other is not well understood. Research conducted by the ICNAF nations has concentrated on the seasonal distribution of the harvestable sizes and the age composition of the stocks. The U.S. has also done work on the growth and distribution of the larvae to define separate stocks. A major gap in our present understanding of what factors affect the yield of the herring resource is our comparative ignorance of their early life history. Herring deposit their eggs in adhesive masses on the ocean bottom at depths up to 100 meters. The eggs develop in these ""egg beds"" for 10-15 days, under heavy predation, until they hatch as yolk sac larvae which rise to the surface. They continue to develop and grow in the surface waters and when the yolk is abosrbed, they must find and capture suitable food to survive. During these stages, they are continually being preyed upon, dispersed, and transported by ocean currents. There is a general consensus among herring biologists that the events which occur during these early stages determine the abundance of a given year class, when it becomes a commercial fishery catch two years later.