Potential spatial and temporal vulnerability of pelagic fish assemblages in the Gulf of Mexico to surface oil spills associated with deepwater petroleum development
Abstract
From the Executive Summary: “Advances in deepwater drilling and production technologies have resulted in the seaward expansion of gas and petroleum platforms beyond the continental shelf in the northern Gulf of Mexico. With increased industrial activities in deeper water comes an increased risk of spills in the deepwater pelagic zone. This region provides habitat for a variety of fish species of considerable ecological, recreational and commercial importance. Compared with fish species inhabiting the inshore waters of the northern Gulf, relatively little is known about the distributions and ecology of these offshore taxa.
Target taxa were pelagic fishes including selected members of the Sargassum community. Pelagic species were considered of primary importance because: (1) most produce large numbers of small eggs with limited yolk reserves that hatch into larvae dependent on plankton in the nearsurface waters for nutrition; (2) most fisheries target pelagic fish taxa; (3) oil is buoyant and will accumulate in the neustonic zone; (4) based on slicks formed by natural petroleum seeps, even oil released from near the bottom will likely rise to the surface; and (5) it is unlikely that there is sufficient information on the distributions of demersal or benthic fishes to make even a wellreasoned inference about their spatial and temporal distributions. Target species selected for
review were bluefin tuna (Thunnus thynnus), yellowfin tuna (T. albacares), blackfin tuna (T. atlanticus), blue marlin (Makaira nigricans), white marlin (Tetrapterus albidus), wahoo (Acanthocybium solanderi), dolphin (Coryphaena hippurus), blue runner (Caranx crysos), spotfin flyingfish (Cypselurus furcatus), Atlantic flyingfish (C. melanurus), ocean sunfish (Mola mola), and selected members of the pelagic Sargassum community: sargassumfish (Histrio histrio), planehead filefish (Monocanthus hispidus), and tripletail (Lobotes surinamensis).
This study was undertaken to review the available information on the distributions of these pelagic fish species in order to predict the spatial and temporal distributions of larval, juvenile and adult life history stages within the surface waters over an area likely to experience increasing gas and petroleum extraction. The study area was defined as the waters over the 200-2000 m isobaths and in some areas deeper than 2000 m extending from 28 ºN south to 26 ºN latitude and extending from 96.4 ºW to 84.3 ºW. This generally rectangular region was divided into three zones (western, central, and eastern). An additional region defined by a triangle with its apex at 87 ºW, 30 ºN and base extending from 90.7 ºW, 28 ºN to 84.3 ºW, 28 ºN was designated the northern zone.
Our review of the literature consulted peer-reviewed and non-peer-reviewed literature as well as Internet resources. This report drew heavily from the National Marine Fisheries Service long-line database and the Southeast Area Monitoring and Assessment Program (SEAMAP) ichthyoplankton surveys. These datasets provided distributional data for adults and larvae, respectively, however, obtaining data on the distributions of juveniles proved to be highly problematic because they avoid planktonic sampling gear and are not captured in commercial fisheries. Consequently, this report focuses on larvae and adults.
For each species, we have summarized the available distributional data on a monthly basis and have attempted to predict the distributions of larvae, adults, and juveniles (when possible) within the study region. Companion software in the form of Microsoft Excel spreadsheets allow the user to query the data to obtain probable distributions within specific locations defined by their longitude and latitude. It is clear that for many taxa, substantial gaps exist in our understanding of their spatial and temporal distributions and we hope that this study will provide a starting point