Distribution patterns of larval and juvenile fishes at offshore petroleum platforms in the north-central Gulf of Mexico

Vertical and horizontal distribution patterns of larval and juvenile fishes were described from five offshore petroleum platforms in the north-central Gulf of Mexico. Light traps and passively-fished plankton nets were used nocturnally between 1995–2000 to collect fishes in surface and deep (15–23 m depth) waters within the platform structure, and light traps were also used in surface waters directly down-current of the platforms. Light traps fished at the surface, as opposed to at-depth, collected greater CPUEs and greater diversity of larval and juvenile fishes. Of the dominant taxa collected by light traps, clupeids, engraulids, synodontids, and presettlement blenniids were most common in surface waters within the platform, while postflexion scombrids and settlement-size blenniids and pomacentrids were most common in surface waters down-current of the platforms. Deep plankton nets collected greater densities of non-clupeiform larval fishes, although surface plankton nets collected greater numbers of taxa. The vertical distribution patterns described for dominant larval fish collected by plankton nets were generally consistent with those from other studies, i.e. clupeid, carangid, sciaenid and scombrid larvae more abundant in surface waters at platforms, and synodontid, bregmacerotid, gobiid and bothid larvae more abundant in deeper waters. Oil and gas platforms likely impact larval and juvenile fish populations, particularly considering their proliferation in the Gulf (i.e., over 4000 platforms). The results from this study provide valuable baseline information for future research investigating how platforms impact the life history stages of fish populations.