Altimetry and lobsters

Image of the Month - July 2001

Simulation of movements of rock lobsters larvae drifting with the currents and wind. The fate of 25 new lobsters every five days from November to February is simulated. Each point represents a single larva. Colors represent what will happen to the lobsters
Animation for 1996-97:
    - 1 image every 12 days : GIF (430Kb)
    - 1 image every 2 days :   GIF (1,72Mb) - MPEG (2,47Mb)
(Credits CSIRO - Marine Research).


What kind of influence are ocean currents in the life of a lobster? To find out, scientists are using satellite altimetry data to map ocean circulation and predict the movements of whatever drifts with these currents. Western Australian rock lobsters (panulirus cygnus) spend the first nine months of their life at sea before returning to coastal areas-if they survive.
This species of great economic value spawns from November to February at the edge of the continental shelf. Studies have shown a correlation between sea surface height and the survival of these young lobsters, so a simulation is made of how they drift with the currents and the wind. However, year-on-year comparisons seem to indicate that ocean circulation and winds have little impact. The young lobsters seem to be sensitive to other factors co-varying with sea level, like temperature.
This kind of research is helping us to better understand annual variations and to evaluate sustainable yearly catch quotas. Rock lobsters are just one example, as altimetry can also improve our knowledge of other marine species and their feeding habits.

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