Abstract

Previous investigations of artificial reef habitat in the northcentral Golf of Mexico have identified the importance of offshore oil and gas platforms to economically-important reef fish, this study investigated the potential importance of another structurally-complex. bard-substrate habitat, a coastal rock jetty system, as a low-salinity, landward endmember of artificial reefs along a transect of tbree oil and gas platforms extending from theinner continental shelf to the shelf break. Quatrefoil light-traps and a bow-mounted plankton pushnet were used to collect fish along a pair of stone rubble jetties at Belle Pass near Fourcbon, Louisiana during new moon and full moon phases from April to August, 1997. Light-traps and the pushnet collected 17,949 and 111,854 fish, respectively. Clupeiformes (engmulids and clupeids) comprised approximately 95% and 70% of the total light-trap and pushnet catch, respectively. Reef (or structure-dependent) fish, though not as abundant, included blennies, gobies, eleotrids, sparids, and lutjanids. The pushnet collected more individuals and taxa than did the light-trap. There were significantly higher pushnet densities and light-trap catch-per-unit-efforts (CPUEs) during new moon periods than full moon periods. This result may reflect a gear avoidance phenomenon where light-traps are more effective when not competing with theambient light of a fun moon and the pushnet is more effective under the darkness of new moon. An altemative bypothesis coold also be related to lunar spawning and/or settlement periodicities. Significantly lower densities and CPUEs were observed at sampling stations located within thejetty walls versus stations located extemally. This result may be related to possible differences in environmental parameters (turbidity, temperature, salinity, and dissolved oxygen) between inner (estuarine) and outer (coastal) sampling stations. Preliminary results indicate that the jetty may serve as a refuge area for presettlement reef fish in the absence of other structurally-complex habitat.

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