Red Snapper Demographics on Artificial Reefs: The Effects of Nearest-Neighbor Dynamics
James H. Cowan, Jr.1 and Arvind Shah2
1 Department of Marine Sciences, University of South Alabama, Mobile AL 36688
2 Department of Mathematics & Statistics, University of South Alabama, Mobile AL 36688
The red snapper is a highly exploited reeffish in the Gulf's snapper-grouper complex that has been commercially important since the late eighteen hundreds (Goodyear 1995). Today, the species is fished heavily both commercially and recreationally (Schirripa and Legault 1997) and is impacted heavily as shrimp fishery bycatch (Goodyear 1995). Thus, red snapper stocks declined rapidly throughout the Gulf until the early 1990s (Szedlmayer and Shipp 1994). In recent years, the stock has begun to recover as a result of management actions; many have attributed this recovery in part to an increase in habitat in the form of artificial reefs. This is especially true off coastal Alabama where more than 20,000 reefs have been constructed since the 1950's, within 3,100 km 2 of permitted artificial reef zones (Ralph Havard, Alabama Department of Conservation-Marine Resources Division, personal communication). Here, we propose to take advantage of the tremendous growth in the Alabama Artificial Reef Program by using a series of experimental reefs placed in a sampling grid south of Dauphin Island. These new reefs were constructed as part of a large effort funded by the State of Alabama (R. Shipp and J. Cowan, Co-PIs) aimed at determining the efficacy of different commercially available artificial reef designs. However, these new reefs were placed without consideration or knowledge of the proximity of previously constructed reefs in their vicinity. We believe that presence or absence of nearby reefs will contribute to the observed variability in population demographics of red snapper on our experimental reefs. Our intent is to use side-scan sonar to map the abundance, distribution, and size (volume) of all artificial reefs within 1 km2 of 6 replicated reefs of 3 designs (18 reefs total), and to relate nearest-neighbor dynamics to measures of red snapper abundance, size, and immigration/emigration rates on the experimental reefs. This new project will directly benefit from, and contribute to, the State of Alabama funded project briefly described in the proposal.