Causes
It was not until 1960 that the phenomenon was explored in-depth by marine biologist Harold Loesch for the journal Ecology. Locals and laymen had based some earlier attempts to explain the animals' strange behaviors on the interaction of sea- and fresh water during the incoming tide.
After researching the oral histories and journalistic records of past jubilees, measuring physical and meteorologic conditions, and taking biological and chemical measurements, Loesch concluded that accumulated organic material on the bay floor could, under a certain set of conditions, result in a rapid depletion of oxygen (hypoxia) in parts of the bay, driving fish to the surface seeking oxygenated water.
Another, more comprehensive study by Edwin B. May in 1973, as well as smaller studies by the Alabama Department of Conservation and Natural Resources and the NOAA confirmed many of Loesch's hypotheses. If wind direction, surface temperature, salinity, and tidal variation interact in ways that allow or promote a jubilee, the situation can develop rather quickly. May sums up the mechanism of action thus:
| “ | Except during jubilees the water inside the 2 meter contour along the eastern shore is well oxygenated. This shallow water extends several hundred meters offshore. During jubilees fishes present there are trapped between the shore and an advancing water mass low in dissolved oxygen; the water at the surface and very close to shore usually has enough oxygen to support them for the short duration of most jubilees. | ” |
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—Edwin B. May |
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Read more about this topic: Mobile Bay Jubilee