Can Artificial Reefs Reduce or Alter User Pressure on Adjacent Natural Reefs? Thomas Maher, Marine Habitats, Inc. Dr. Vernon R. Leeworthy, NOAA Special Projects Office Ned Stone, NOAA Special Projects Office Presented at the 8 th International Conference on Artificial Reefs and Artificial Habitats April 13, 2005 Biloxi, Mississippi USA

Introduction  A potential new use for artificial reefs  Three study objectives  Preliminary results for the first objective

Spiegel Grove

Methodology Two databases collected for the pre- and post-deployment periods: Pre-deployment period from August 2001 through May 2002 (10 months) Post-deployment period from July 2002 through July 2003 (12 months)

Methodology Types of data collected were: Dive charter log books On-water surveys of all users Total use from all sectors (divers, snorkelers, fishermen and non-consumptive users) extrapolated from on-water survey data

Results Importance of summer months Overall increase of use Decreased use on adjacent natural reefs Increased use on adjacent artificial reefs

Ten Month Pre-Deployment Use Levels (August 2001 to May 2002): SCUBA Divers Only Reef Log Book Adjusted All Type Data Data Sectors Natural 101, , ,895 (83%) Artificial 22,176 25,744 28,890 (17%) Total 123, , ,785 (89%)

Ten Month Post-Deployment Use Levels (August 2002 to May 2003): SCUBA Divers Only Reef Log Book Adjusted All Type Data Data Sectors Natural 93, , ,060 (66%) Artificial 46,149 53,616 63,001 (34%) Total 139, , ,061 (86%)

Ten Month Post-Deployment Use Levels (August 2002 to May 2003): SCUBA Divers Only Reef Log Book Adjusted All Type Data Data Sectors Natural 93, , ,060 (66%) Artificial 46,149 53,616 63,001 (34%) Spiegel 18,669 21,888 26,045 (14% Groveof all use) Total 139, , ,061

Comparison of Pre- and Post - Deployment Use Levels SCUBA Divers Only - All Sectors Type Pre- Post- Change Natural 139, ,060 17,835 (-13%) Artificial 28,890 63,001 34,111 (+118%) Spiegel N/A 26,045 26,045 Grove (14% of all use) Total 168, ,061 16,276 (+10%)

Ten Month Pre-Deployment Use Levels (August 2001 to May 2002): All Users Reef Log Book Adjusted All Type Data Data Sectors Natural 124, , ,290 (87%) Artificial 26,651 30,638 41,778 (13%) Total 150, , ,068

Ten Month Post-Deployment Use Levels (August 2002 to May 2003): All Users Reef Log Book Adjusted All Type Data Data Sectors Natural 110, , ,753 (68%) Artificial 54,431 62, ,836 (32%) Total 164, , ,589

Ten Month Post-Deployment Use Levels (August 2002 to May 2003): All Users Reef Log Book Adjusted All Type Data Data Sectors Natural 110, , ,753 (68%) Artificial 54,431 62, ,836 (32%) Spiegel 19,052 22,321 28,386 Grove (8% of all use) Total 164, , ,589

Comparison of Pre- and Post - Deployment Use Levels All Users - All Sectors Type Pre- Post- Change Natural 274, ,753 37,537 (-14%) Artificial 41, ,836 67,058 (+160%) Spiegel N/A 28,386 28,386 Grove (8% of all use) Total 316, ,589 29,521 (+9%)

Discussion Preliminary results indicate that highly preferred artificial reefs such as large ships can alter user patterns and assist in reducing user pressure on natural reefs We need to assess if the first year trend in altered user pressure has continued into the future

Future Analyses Additional analyses being undertaken: 1. Net economic impacts on the local economy 2. Location and magnitude of natural reef sites where user pressure was reduced