Comparison of the fisheries value of platforms used as artificial reefs: standing, toppled, and partially removed
Abstract
Artificial reefs have been embraced as a management tool by a wide range of user groups
(recreational and commercial fishers, recreational divers, and environmental advocacy
organizations), and federal and state resource mangers. While these groups view artificial reefs
positively, little information exists on associated nekton assemblages, particularly at deepwater
artificial reefs.
The purpose of this project is to measure and compare the species composition, abundance and size
frequency distribution of fishes associated with a toppled platform, a partially removed platform and
a standing production platform in the Northern Gulf. Comparison of acoustically derived fish
densities at the artificial reef sites and the open waters of the GOM will answer this question using
a Biosonics model DT5000 scientific echosounder/multiplexer-equalizer and a remotely operated
underwater vehicle for visual census techniques.
Fish density around the standing platform (HI350) varied with both depth and side. We found lowest
densities near the bottom and adjacent to the platform where mean fish density was 0.0001 fish per
cubic meter (FPCM) and highest densities near the surface at .05 fish per cubic meters. Fish
densities around partial removed platform (HI 355) were roughly 2-3 orders of magnitude higher
over the top of the platform. Mean fish density over HI355 was 0.26 fish/m3. Densities around the
toppled platform (WC617), produced similar results to HI355, except that the density at WC 617
was roughly ½ that of HI355.
We conclude that fish abundance around oil and gas platforms is much higher than adjacent soft
bottom sediment. The platforms provide critical habitat for many important commercial and
recreational species for Louisiana citizens. Our general impression remains that standing platforms
are the most desirable configuration. We continue to support partial removal in water depths greater
than 200 feet and toppling in place in shallower depths.