Oceanographic information

Tunas are large pelagic and highly migratory fishes which need warm waters for reproduction and larval growth. Some species are able to bear cold waters because of a more efficient thermoregulation. This partially explains differences in the geographical and vertical distributions of tunas: Some, such as skipjack and yellowfin tuna, are warm-waters species, whereas others, such as albacore and Atlantic bluefin tuna, are temperate-waters species.

As is the case with most exploited fish populations, environmental changes can substantially affect productivity (e.g., through changes in recruitment and growth), spatial distribution and catchability of tunas and billfishes. The well known El Niño Southern Oscillation (see the link for the CAS, below) has been shown to modify both the horizontal and vertical distribution of some tropical tunas and consequently their catchability to several fishing gears. Large-scale climatic events, such as the North Atlantic Oscillation (see the link for the CAS, below), has been also advocated to impact the recruitment success of temperate tunas. Some temperate tunas have displayed conspicuous long-term fluctuations which were finally related to some modifications of their migration patterns in response to variations in sea surface temperature. Understanding the responses of tunas to environmental changes is thus not only important from an ecological viewpoint, but also from a conservation and management one.

The Sub-Committee on Ecosystems deals with many issues, including the effects of the environment on tuna populations (this was previously studied under the Sub-Committee on the Environment which last met in 2005).

GAO: Gestionnaire d'Applications Océanographiques

GAO is a software for processing oceanographic data for fisheries research. It is built from large datasets that include oceanographic stations (temperature, salinity, dissolved oxygen, phosphates and nitrates at depth levels), vertical temperature profiles (MBTs, XBTs, CTDs), outputs of the OPA ocean circulation model (temperature, salinity, current vectors, vertical velocity, at 13 depth levels), sea surface temperature and wind-derived fields, Topex sea level anomalies and soon, a temperature-at-depth database at grid points on the global ocean.
These datasets are prepared in a way enabling data storage and processing on the local hard disk of a standard personal computer. A Windows software performs extraction and queries on these databases. The goal of GAO is to be an easy-to-handle tool for working groups in the fisheries domain, where quick reference to physical environment is sometimes required. (For more information, contact Marsac@ird.fr).
See also Marsac (2004). GAO: an environmental database and software designed for fisheries biologists. ICCAT SCRS/2004/172.

Links to other useful environmental sites

From: Fromentin, Royer and Marsac (2004). Open environmental databases for open-sea fisheries biologists. ICCAT SCRS/2004/171

Last update: 11 Jul 2007