OBSERVATIONS ON THE FISH FAUNA ASSOCIATED WITH 

 OFFSHORE PLATFORMS IN THE NORTHEASTERN GULF OF MEXICO 



Robert W. Hastings,^ Larry H. Ogren.^and Michael T. Mabry^ 



ABSTRACT 



The fish fauna associated with two U.S. Navy research platforms. Stage I and Stage 11, in the 

 northeastern Gulf of Mexico off Panama City, Fla., was studied at irregular intervals from 1970 to 

 1974. Such platforms function as artificial reef habitats and support diverse and abundant fish 

 populations not normally characteristic of the open sandy bottoms in the area. 



A total of 101 taxa (identified to family or species) was recorded at the two platforms; 61 species 

 were observed at Stage I in water 32 m deep and 86 taxa at Stage II in water 18 m deep. The greater 

 number of species recorded at the shallower location may be more a result of the greater number of 

 observations made there than of differences in the two habitats. The number of species present at the 

 platforms varies considerably at different times of the day and year. Species numbers are greatest 

 during the summer and fall, but many species begin to move offshore or southward as the water 

 temperature drops, and only about 50-60% of those recorded at the platform remain in December. The 

 number of species diminishes to about 16% in February at Stage II, then increases gradually with the 

 rising water temperature in the spring. 



Major species occupying the platform habitats include fishes usually characteristic of pelagic, 

 inshore (coastal or estuarine), and rocky reef environments. At the platforms, the pelagic species and 

 most of the larger predators occupy various levels of the water column, either directly below or 

 surrounding the structure, while most of the other species are associated either with the pilings and 

 cross-members of the platform or with the bottom. For some of the species, the platform provides food 

 and shelter, while for others, it offers only shelter. Some species may be present only to feed on the 

 numerous fishes and other organisms concentrated there. Diel rhythms of activity are obvious for 

 many of the fishes, with some species active only during the day, and others only at night. 



Offshore oil drilling platforms are known to at- 

 tract various species of marine fishes and thus 

 function as artificial reefs (Carlisle et al. 1964; 

 Treybig 1971). Anglers often recognize such plat- 

 forms as desirable fishing sites. Carlisle et al. 

 (1964) documented the development of fish popu- 

 lations (as well as populations of encrusting or- 

 ganisms) at two platforms constructed off the 

 coast of California. The supporting piles and 

 cross-members of such platforms provide hard 

 substrates for the settling of pelagic larvae of en- 

 crusting invertebrates and algae which, with 

 their associated invertebrate populations, pro- 

 vide food and shelter for reef fishes attracted to 

 the structures. In addition, many pelagic fishes 

 congregate about these platforms, attracted 

 either by the solid, reeflike nature of the support- 

 ing structures, or by the numerous smaller forage 

 organisms in the area. 



'Department of Biology, Rutgers University, Camden, NJ 

 08102. 



^Gulf Coastal Fisheries Center Panama City Laboratory, Na- 

 tional Marine Fisheries Service, NOAA, Panama City, FL 

 32401. 



'Tampa Marine Institute, 1310 Shoreline Drive, Tampa, FL 

 33605. 



Manuscript accepted September 1975. 

 FISHERY BULLETIN: VOL. 74, NO. 2, 1976. 



Many comparable platforms have been con- 

 structed in the Gulf of Mexico since the 1940's, 

 but no studies of their associated fish faunas have 

 been reported, even though they are known to 

 attract numerous species of fishes. Current 

 studies by personnel of the University of South- 

 western Louisiana have documented the fish 

 fauna of drilling platforms off the coast of 

 Louisiana (Sonnier et al. 1976). This paper re- 

 cords the fish populations observed around two 

 offshore platforms in the northeastern Gulf of 

 Mexico off Panama City, Fla. 



LOCATION AND TIME OF STUDY 



Two research platforms operated by the U.S. 

 Navy off the coast of Panama City are referred to 

 as Stage I and Stage II. Stage I is 17.7 km offshore 

 in water 32 m deep (lat. 30°00.5'N, long. 

 85°54.2'W). Stage II (Figure 1) is 3.2 km offshore 

 in water 18 m deep (lat. 30°07.2'N, long. 

 85°46.4'W). The pilings of Stage I form a square 

 on the sea bottom with each side measuring 32.6 

 m, whereas those of Stage II measure 19.1 m. The 

 two platforms were the sites of biofouling studies 



387 



