OCS Study 

MMS 2000-005 

Coastal Marine Institute 

Seasonal and Spatial Variation in the 

Biomass and Size Frequency Distribution 

of the Fish Associated with Oil and Gas 

Platforms in the Northern Gulf of Mexico 

U.S. Department of the Interior cooperative agreement 

Minerals 1Vlanagement Service Coastal Marine Institute 

Gulf of Mexico OCS Region Louisiana State University 
OCS Study 

M M S 2000-005 

Coastal Marine Institute 

Seasonal and Spatial Variation i n the 

Biomass and Size Frequency Distribution 

of the Fish Associated with Oil and Gas 

Platforms in the Northern Gulf of Mexico 

Authors 

David R. Stanley 

and 

Charles A . Wilson 

February 2000 

Prepared under MMS Contract 

14-35-0001-30660-19915 

by 

Coastal Marine Institute 

Louisiana State University 

Baton Rouge, Louisiana 70803 

Published by 

U .S. Department of the Interior Cooperative Agreement 

Minerals 7management Service Coastal Marine Institute 

Gulf of Mexico OCS Region Louisiana State University 

DISCLAIMER 

This report was prepared under contract between the Minerals Management Service (MMS) 

and Coastal Fisheries Institute, Louisiana State University (LSU). This report has been 

technically reviewed by the MMS, and, and it has been approved for publication . Approval 

does not signify that the contents necessarily reflect the views and policies of LSU or the 

MMS, nor does mention of trade names or commercial products constitute endorsement or 

recommendation for use. It is, however, exempt from review and compliance with the MMS 

editorial standard . 

REPORT AVAILABILITY 

Extra copies of the report may be obtained from the Public Information Office (Mail Stop 

5034) at the following address: 

U.S . Department of the Interior 

Mineral Management Service 

Gulf of Mexico Region 

Public Information Office (MS #5034) 

1201 Elmwood Boulevard 

New Orleans, Louisiana 70123-2394 

Telephone: (504) 736-2519 or 

1-800-200-GULF 

CITATION 

Suggested Citation : 

Stanley, D.R . and C.A . Wilson 2000 . Seasonal and Spatial Variation in the Biomass and Size 

Frequency Distribution of Fish Associated with Oil and Gas Platforms in 

the Northern Gulf Of Mexico . OCS Study MMS 2000-005 . Prepared 

by the Coastal Fisheries Institute, Center for Coastal, Energy and 

Environmental Resources Louisiana State University . U.S. Dept . of 

the Interior, Minerals Mgmt. Service, Gulf of Mexico OCS Region, 

New Orleans, LA 252pp. 

iii 

TABLE OF CONTENTS 

Page 

LIST OF FIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii 

LIST OF TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix 

ACKNOWLEDGMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvii 

EXECUTIVE SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xix 

INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 

METHODS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 

Site Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 

Data Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 

RESULTS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 

South Timbalier 54 

Vertical Density Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 

Horizontal Density Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10 

Estimated Number of Fish and Species Composition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10 

Grand Isle 94 

Vertical Density Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 

Horizontal Density Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 

Estimated Number of Fish and Species Composition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14 

Green Canyon 18 

15 Vertical Density Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

Horizontal Density Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 

Estimated Number of Fish and Species Composition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16 

South Timbalier 54 

Target Strength Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 

Grand Isle 94 

Target Strength Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 

Green Canyon 18 

Target Strength Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21 

DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23 

Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31 

REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33 

TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39 

v 
FIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137 

APPENDIX 1 

Current, Temperature, Salinity and Oxygen Data Coincident 

with Acoustic Data at South Timbalier 54 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153 

APPENDIX 2 

Current, Temperature, Salinity and Oxygen Data Coincident 

with Acoustic Data at Grand Isle 94 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181 

APPENDIX 3 

Current, Temperature, Salinity and Oxygen Data Coincident 

with Acoustic Data at Green Canyon 18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213 

vi 
LIST OF FIGURES 

Figure Page 

Figure 1 . Position of the three study sites South Timbalier 54 (ST54), 

Grand Isle 94 (GI94) and Green Canyon 18 (GC 18) off the 

Louisiana coast . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137 

Figure 2 Schematic view of stationary hydroacoustic transducer 

deployment to measure in situ target strength and density of 

fishes throughout the water column on each side of the platform 

for the three study sites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138 

Figure 3 . Schematic view of stationary hydroacoustic transducer 

deployment to measure horizontal relative density of fishes 

associated with petroleum platforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139 

Figure 4 . Mean fish density (number of fish/m3) by year at Green Canyon 18 

(GC 18) and Grand Isle 94 (GI94) from July 1994 to March 1997 and 

South Timbalier (ST54) from August 1995 to February 1997 . . . . . . . . . . . . . . . . . 140 

Figure 5 . Mean fish density (number of fish/m3) by season at Green Canyon 18 

(GC 18) and Grand Isle 94 (GI94) from July 1994 to March 1997 and 

South Timbalier (ST54) from August 1995 to February 1997 . . . . . . . . . . . . . . . . . 141 

Figure 6. Mean fish density (number of fish/m3) by time of day from Green 

Canyon 18 (GC18) and Grand Isle 94 (GI94) from July 1994 to 

March 1997 and South Timbalier (ST54) from August 1995 to 

February 1997 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142 

Figure 7. Mean fish density (number of fish/m3) by platform side from Green 

Canyon 18 (GC18) and Grand Isle 94 (GI94) from July 1994 to 

March 1997 and South Timbalier (ST54) from August 1995 to 

February 1997 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143 

Figure 8 . Mean fish density (number of fish/m3) by depth at Grand Isle 94 

(GI94) from July 1994 to March 1997 and South Timbalier (ST54) 

from August 1995 to February 1997 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144 

Figure 9 . Mean fish density (number of fish/m') and dissolved oxygen (ppm) 

by depth at South Timbalier (ST54) from July 1996 sample . . . . . . . . . . . . . . . . . . 145 

vii 
Figure 10. Mean relative fish density (number of fish/m') with distance from the 

platform at Green Canyon 18 (GC 18) and Grand Isle 94 (GI94) from 

July 1994 to March 1997 and South Timbalier (ST54) from August 

1995 to February 1997 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .146 

Figure 11 . Estimated number of bluerunner for each quarterly sample period at 

Green Canyon 18 (GC 18) and Grand Isle 94 (GI94) from July 1994 

to March 1997 and South Timbalier (ST54) from August 1995 to 

February 1997 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147 

Figure 12. Estimated number of fishes for each quarterly sample period at Green 

Canyon 18 (GC18) and Grand Isle 94 (GI94) from July 1994 to 

March 1997 and South Timbalier (ST54) from August 1995 to 

February 1997 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148 

Figure 13 . Estimated number of greater amberjack, horseeye jack, mangrove 

snapper and red snapper fishes for each quarterly sample period at 

Grand Isle 94 (GI94) from July 1994 to March 1997 . . . . . . . . . . . . . . . . . . . . . . . . . . 149 

Figure 14. Mean fish density (number of fish/m3) by depth at Green Canyon 18 

from July 1994 to March 1997 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150 

Figure 15. Estimated number of greater amberjack, almaco jack, barracuda, 

creolefish, and Bermuda chub for each quarterly sample period at 

Green Canyon 18 from October 1994 to March 1997 . . . . . . . . . . . . . . . . . . . . . . . . . 151 

viii 
LIST OF TABLES 

Table Pee 

Table 1 . RBD ANOVA (block on platform side) results of vertical log fish 

density (log (fish density/m 3) with platform side, year, season, 

time of day, depth, current vectors, temperature, salinity, dissolved 

oxygen and selected interactions at the ST54 petroleum platform . . . . . . . . . . . . . 39 

Table 2. RBD ANOVA (block on platform side) results of horizontal log 

relative fish density (log (fish density/m 3) with platform side, year, 

season, time of day, distance from the platform and selected 

interactions at the ST54 petroleum platform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 

Table 3a. Number enumerated and percent species composition (in parentheses) 

by depth strata at South Timbalier 54 from July 30 - August 1, 1995 

from visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 

Table 3b. Number enumerated and percent species composition (in parentheses) 

by depth strata at South Timbalier 54 from October 24 - 25, 1995 

from visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 

Table 3c . Number enumerated and percent species composition (in parentheses) 

by depth strata at South Timbalier 54 from January 30 - February 1, 

1996 from visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 

Table 3d . Number enumerated and percent species composition (in parentheses) 

by depth strata at South Timbalier 54 from June 6 - 7, 1996 from 

visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 

Table 3e. Number enumerated and percent species composition (in parentheses) 

by depth strata at South Timbalier 54 from July 17 - 18, 1996 from 

visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 

Table 3f. Number enumerated and percent species composition (in parentheses) 

by depth strata at South Timbalier 54 from March 28 - 29, 1997 

from visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 

Table 3g. Mean number enumerated and percent species composition (in 

parentheses) by depth strata at South Timbalier 54 for all research 

trips from July 1995 through March 1997 from visual point count 

surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 

ix 
Table 4a. Estimated number of fish by species (with 95 % confidence intervals) 

by depth strata at South Timbalier 54 from July 30 - August 1, 

1995 from hydroacoustic and visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . 48 

Table 4b. Estimated number of fish by species (with 95 % confidence intervals) 

by depth strata at South Timbalier 54 from October 24 - 25, 1995 

from hydroacoustic and visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 

Table 4c. Estimated number of fish by species (with 95 % confidence intervals) 

by depth strata at South Timbalier 54 from January 30 - February 1, 

1996 from hydroacoustic and visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . 50 

Table 4d . Estimated number of fish by species (with 95 % confidence intervals) 

by depth strata at South Timbalier 54 from June 6 - 7, 1996 from 

hydroacoustic and visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 

Table 4e. Estimated number of fish by species (with 95 % confidence intervals) 

by depth strata at South Timbalier 54 from July 17 - 18, 1996 from 

hydroacoustic and visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 

Table 4f. Estimated number of fish by species (with 95 % confidence intervals) 

by depth strata at South Timbalier 54 from March 28 - 29, 1997 from 

hydroacoustic and visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 

Table 4g . Mean estimated number of fish by species (with 95 % confidence 

intervals) by depth strata at South Timbalier 54 from all research 

trips from July 1995 through March 1997 from hydroacoustic and 

visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 

Table 5 . RBD ANOVA (block on platform side) results of vertical log fish 

density (log(number of fish/m 3) with platform side, year, season, 

time of day, depth, current vectors, temperature, salinity, dissolved 

oxygen and selected interactions at the GI94 petroleum platform . . . . . . . . . . . . . 55 

Table 6. RBD ANOVA (block on platform side) results of horizontal relative 

log fish density (log(number of fish/m 3) with platform side, year, 

season, time of day, distance from the platform and selected 

interactions at the GI94 petroleum platform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 

Table 7a. Number enumerated and percent species composition (in parentheses) 

by depth strata at Grand Isle 94 from August 9 - 10, 1994 from 

visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 

x 
Table 7b. Number enumerated and percent species composition (in parentheses) 

by depth strata at Grand Isle 94 from November 8 - 9, 1994 from 

visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 

Table 7c . Number enumerated and percent species composition (in parentheses) 

by depth strata at Grand Isle 94 from January 31, 1995 from visual 

point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 

Table 7d . Number enumerated and percent species composition (in parentheses) 

by depth strata at Grand Isle 94 from September 10 - 11, 1995 from 

visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 

Table 7e . Number enumerated and percent species composition (in parentheses) 

by depth strata at Grand Isle 94 from November 14 - 15, 1995 from 

visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 

Table 7f. Number enumerated and percent species composition (in parentheses) 

by depth strata at Grand Isle 94 from February 13 - 14 , 1996 from 

visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 

Table 7g. Number enumerated and percent species composition (in parentheses) 

by depth strata at Grand Isle 94 from April 23 - 24, 1996 from 

visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 

Table 7h . Number enumerated and percent species composition (in parentheses) 

by depth strata at Grand Isle 94 from September 3-4, 1996 from 

visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 

Table 7i. Number enumerated and percent species composition (in parentheses) 

by depth strata at Grand Isle 94 from November 7 - 8, 1996 from 

visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73 

Table Tj . Number enumerated and percent species composition (in parentheses) 

by depth strata at Grand Isle 94 from March 9 - 10, 1997 from 

visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 

Table 7k. Number enumerated and percent species composition (in parentheses) 

by depth strata from all trips to Grand Isle 94 from August 1994 - 

March 1997 from visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 

Table 8a. Estimated number of fish by species (with 95 % confidence intervals) 

by depth strata at Grand Isle 94 from August 9 - 10, 1994 from 

hydroacoustic and visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 

xi 
Table 8b . Estimated number of fish by species (with 95 % confidence intervals) 

by depth strata at Grand Isle 94 from November 8 - 9, 1994 from 

hydroacoustic and visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 

Table 8c. Estimated number of fish by species (with 95 % confidence intervals) 

by depth strata at Grand Isle 94 from January 31, 1995 from 

hydroacoustic and visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 

Table 8d. Estimated number of fish by species (with 95 % confidence intervals) 

by depth strata at Grand Isle 94 from September 10 - 11, 1995 from 

hydroacoustic and visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SS 

Table 8e. Estimated number of fish by species (with 95 % confidence intervals) 

by depth strata at Grand Isle 94 from November 14 - 15, 1995 from 

hydroacoustic and visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 

Table 8f. Estimated number of fish by species (with 95 % confidence intervals) 

by depth strata at Grand Isle 94 from February 13 - 14, 1996 from 

hydroacoustic and visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89 

Table 8g . Estimated number of fish by species (with 95 % confidence intervals) 

by depth strata at Grand Isle 94 from April 23 - 24, 1996 from 

hydroacoustic and visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 

Table 8h. Estimated number of fish by species (with 95 % confidence intervals) 

by depth strata at Grand Isle 94 from September 3 - 4, 1996 from 

hydroacoustic and visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 

Table 8i. Estimated number of fish by species (with 95 % confidence intervals) 

by depth strata at Grand Isle 94 from November 7 - 8, 1996 from 

hydroacoustic and visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 

Table 8j . Estimated number of fish by species (with 95%a confidence intervals) 

by depth strata at Grand Isle 94 from March 9 - 10, 1997 from 

hydroacoustic and visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 

Table 8k. Estimated number of fish by species (with 95 % confidence intervals) 

by depth strata from all trips to Grand Isle 94 from August 1994 - 

March 1997 from hydroacoustic and visual point count surveys . . . . . . . . . . . . . . 99 

Table 9 . RBD ANOVA (block on platform side) results of vertical log fish 

density (log(number of fish/m 3) with platform side, year, season, 

time of day, depth, current vectors, temperature, salinity, dissolved 

oxygen and selected interactions at the GC 18 petroleum platform . . . . . . . . . . . 101 

xii 
Table 10 . RBD ANOVA (block on platform side) results of horizontal log 

relative fish density (log(number of fish/m 3) with platform side, 

year, season, time of day, distance from the platform and selected 

interactions at the GC 18 petroleum platform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 

Table l la. Number enumerated and percent species composition (in parentheses) 

by depth strata at Green Canyon 18 from October 4 - 5, 1994 from 

visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 

Table l lb. Number enumerated and percent species composition (in parentheses) 

by depth strata at Green Canyon 18 from November 30 - December 

1, 1994 from visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104 

Table l lc . Number enumerated and percent species composition (in parentheses) 

by depth strata at Green Canyon 18 from January 20 - 21, 1995 from 

visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105 

Table l Id . Number enumerated and percent species composition (in parentheses) 

by depth strata at Green Canyon 18 from May 11 - 12, 1995 from 

visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106 

Table l le. Number enumerated and percent species composition (in parentheses) 

by depth strata at Green Canyon 18 from July 11 - 12, 1995 from 

visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 

Table l lf. Number enumerated and percent species composition (in parentheses) 

by depth strata at Green Canyon 18 from December 1 - 2, 1995 from 

visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108 

Table l lg . Number enumerated and percent species composition (in parentheses) 

by depth strata at Green Canyon 18 from March 4 - 5, 1995 from 

visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 

Table l lh . Number enumerated and percent species composition (in parentheses) 

by depth strata at Green Canyon 18 from April 9 -10, 1996 from 

visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 

Table 11 i. Number enumerated and percent species composition (in parentheses) 

by depth strata at Green Canyon 18 from September 11 - 12, 1996 

from visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111 

Table l lj . Number enumerated and percent species composition (in parentheses) 

by depth strata at Green Canyon 18 from November 18 - 20, 1996 

from visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112 

xiii 
Table l lk. Number enumerated and percent species composition (in parentheses) 

by depth strata at Green Canyon 18 from March 4 - 5, 1997 from 

visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 

Table 111. Number enumerated and percent species composition (in parentheses) 

by depth strata from all trips to Green Canyon 18 from August 1994 - 

March 1997 from visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114 

Table 12a. Estimated number of fish by species (with 95 % confidence intervals) 

by depth strata at Green Canyon 18 from October 4 -5, 1994 from 

hydroacoustic and visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116 

Table 12b. Estimated number of fish by species (with 95 % confidence intervals) 

by depth strata at Green Canyon 18 from November 30 - December 1, 

1994 from hydroacoustic and visual point count surveys . . . . . . . . . . . . . . . . . . . . . .117 

Table 12c. Estimated number of fish by species (with 95 % confidence intervals) 

by depth strata at Green Canyon 18 from January 20 - 21, 1995 from 

hydroacoustic and visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .118 

Table 12d . Estimated number of fish by species (with 95 % confidence intervals) 

by depth strata at Green Canyon 18 from July 11 - 12, 1995 from 

hydroacoustic and visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119 

Table 12e. Estimated number of fish by species (with 95 % confidence intervals) 

by depth strata at Green Canyon 18 from December 1 - 2, 1995 from 

hydroacoustic and visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120 

Table 12f. Estimated number of fish by species (with 95 % confidence intervals) 

by depth strata at Green Canyon 18 from March 4 - 5, 1996 from 

hydroacoustic and visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121 

Table 12g . Estimated number of fish by species (with 95 % confidence intervals) 

by depth strata at Green Canyon 18 from April 9 -10, 1996 from 

hydroacoustic and visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122 

Table 12h . Estimated number of fish by species (with 95 % confidence intervals) 

by depth strata at Green Canyon 18 from September 11 - 12, 1996 

from hydroacoustic and visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123 

Table 12i . Estimated number of fish by species (with 95 % confidence intervals) 

by depth strata at Green Canyon 18 from November 18 - 20, 1996 

from hydroacoustic and visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124 

xiv 
Table 12j . Estimated number of fish by species (with 95 % confidence intervals) 

by depth strata at Green Canyon 18 from March 4 - 5, 1997 from 

hydroacoustic and visual point count surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125 

Table 12k. Estimated number of fish by species (with 95 % confidence intervals) 

by depth strata from all trips to Green Canyon 18 from August 1994 - 

March 1997 from hydroacoustic and visual point count surveys . . . . . . . . . . . . . 126 

Table 13 . RBD ANOVA (block on platform side) results of vertical target 

strength (dB) with platform side, year, season, time of day, depth, 

current vectors, temperature, salinity, dissolved oxygen and selected 

interactions at the ST54 petroleum platform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128 

Table 14 . Mean target strengths (dB), with Tukey's studentized means test 

results by season at South Timbalier 54 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129 

Table 15 . Mean target strengths (dB) with Tukey's studentized means test results 

by time of day at South Timbalier 54 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129 

Table 16. Mean target strengths (dB) with Tukey's studentized means test result 

by platform side at South Timbalier 54 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130 

Table 17. Mean target strength (dB) with Tukey's studentized means test by 

water depth (m) at South Timbalier 54 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130 

Table 18. RBD ANOVA (block on platform side) results of vertical target 

strength (dB) with platform side, year, season, time of day, depth, 

current vectors, temperature, salinity, dissolved oxygen and selected 

interactions at the GI94 petroleum platform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131 

Table 19 . Mean target strength (dB) with Tukey's studentized means test by 

year at Grand Isle 94 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132 

Table 20. Mean target strength (dB) with Tukey's studentized means test by 

season at Grand Isle 94 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132 

Table 21 . Mean target strength (dB) with Tukey's studentized means test by 

time of day at Grand Isle 94 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133 

Table 22. Mean target strength (dB) with Tukey's studentized means test by 

platform side at Grand Isle 94 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133 

Table 23. Mean target strength (dB) with Tukey's studentized means test by 

water depth (m) at Grand Isle 94 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134 

xv 
Table 24 . RBD ANOVA (block on platform side) results of vertical target 

strength (dB) with platform side, year, season, time of day, depth, 

current vectors, temperature, salinity, dissolved oxygen and selected 

interactions at the GC 18 petroleum platform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135 

Table 25. Mean target strength (dB) with Tukey's studentized means test by 

time of day at Green Canyon 18 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136 

Table 26 . Mean target strength (dB) with Tukey's studentized means test by 

platform side at Green Canyon 18 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136 

Table 27 . Mean target strength (dB) with Tukey's studentized means test by 

water depth (m) at Green Canyon 18 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136 

xvi 
ACKNOWLEDGMENTS 

The authors wish to thank Mobil USA Inc., Exxon Company USA, the Minerals 

Management Service, and the Louisiana Department of Wildlife and Fisheries, Louisiana 

Artificial Reef Program for supporting this research program . We would especially like to 

thank the staff of the petroleum platforms South Timbalier 54, Grand Isle 94 and Green 

Canyon 18 for their help and tolerance throughout the research project. 

xvii 

EXECUTIVE SUMMARY 

The largest artificial reef complex in the world, although unplanned, is composed of the 4,000 

petroleum platforms scattered across the outer continental shelf (OCS) of the northern Gulf of 

Mexico (GOM). Scientists have hypothesized that artificial reefs and platforms improve 

and/or diversify habitat, increase resources, modify the assemblages of organisms in the region 

or concentrate existing resources. The placement of these defacto reefs has undoubtedly 

impacted the regional marine community although little information is available. Only recently 

have assessment methods been developed to test these and other hypotheses concerning 

artificial reefs. 

Scientific investigations of fish assemblages at petroleum platforms did not start until 

the late 1970's . The consisted of visual surveys conducted by SCUBA divers, remotely 

operated underwater vehicles (ROV) and stationary cameras; the majority were short term, 

often only "snapshots" of the fishes at each site . The results of this early research provided 

insights into structure associated assemblages; abundance and species composition varied with 

platform, water depth and time of the year. However, results were difficult to compare due to 

problems with limited visibility, gear bias, diver avoidance and a lack of standardized survey 

methodology . 

Earlier research demonstrated that towed hydroacoustics could be used to measure fish 

density near petroleum platforms off Cameroon. In response to the difficulty in assessing the 

fisheries resources associated with petroleum platforms and the bias's inherent with visual 

surveys. We used complimentary sampling methods of visual surveys and quantitative dual 

beam hydroacoustic surveys to document the assemblage of fishes associated with petroleum 

platforms in the northern Gulf of Mexico. With the sampling protocol established, the 

objectives of this research were to use dual beam hydroacoustics in conjunction with visual 

point count surveys to measure the density and size distribution of fishes associated with three 

petroleum platforms off the Louisiana coast. The goals of this research were to determine the 

effect of water depth on fish density, size distribution and species composition and ultimately 

to measure the fisheries value of platforms of different depths in the same geographical region . 

The results of this project demonstrate the variability in abundance, size distribution 

and species composition of fishes associated with petroleum platforms. Similar results from 

earlier studies have been found with natural and artificial reefs . The variability in density and 

the size distribution of fishes at petroleum platforms in this project was linked to temporal, 

spatial and environmental variables. 

At the shallowest site, South Timbalier 54 (ST54, water depth 22 m), the decline in fish 

density with distance from the platform was precipitous; after a distance of 18 m fish densities 

were similar to that of the open waters of the northern Gulf of Mexico. At the deeper sites a 

drop in fish density with distance from the site existed, although fish density was much higher 

to greater distances. At both Grand Isle 94 (GI94, water depth 60 m) and Green Canyon 18 

(GC18, water depth 219 m) fish density approached that found in the open waters of the Gulf 

of Mexico after a distance of approximately 50 m. Despite some complications 

xix 
hydroacoustics again illustrated its effectiveness in defining "area of influence" of the platform 

or the effective size of the artificial reef to the fish assemblage. As we defined it, the area of 

influence extended 10 m at GC18 and 18 m at GI94 ; fish densities within these distances were 

significantly higher than densities at greater distances and while this may result in conservative 

estimates of total abundance we feel it more accurately reflects the true abundance of fishes at 

the sites . 

Six species made up over 90% of the fishes observed at each site on any survey and 

platform assemblages could be characterized as not specious and dominated by a few individual 

species . By site the dominant six species (highest to lowest abundance) were; GC 18 ; 

creolefish, blue runner, Bermuda chub, almaco jack, amberjack, and barracuda; GI94; blue 

runner, horseeye jack, red snapper, mangrove snapper, gray triggerfish and barracuda; ST54; 

Atlantic spadefish, bluefish, blue runner, mangrove snapper, red snapper and sheepshead . 

While the species found at each site were somewhat unique and the dominant species at each 

site was different, a large amount of overlap of observed species existed between sites, 

especially adjacent sites. Seasonal migrations were common at each of the study sites. Since 

this research took place throughout the year we were able to document the seasonality alluded 

to by past research but not well documented. Common seasonal migrations observed in the 

winter were the appearance of significant numbers of Florida pompano and bluefish at ST54; 

and the appearance of blue runner and barracuda at GI94 and GC 18. Summer seasonal 

observations included the appearance of tarpon and cobia at ST54, an increase in abundance of 

cobia, red snapper, greater amberjack and almaco jack at GI94, while no summer migrants 

were observed at GC 18 . 

Comparison of results from this research with other petroleum platform studies from 

the northern Gulf of Mexico revealed similarities as well as significant differences in density 

and abundance . Comparison of acoustically derived estimates of density from our past 

research showed similar values with those from this project especially at ST54 and GI94. 

Mean densities from our earlier work at a site in 24 m of water were 0.244 (+/- 0.062, 95% 

confidence interval) fish-m-', while mean densities found during this project were 0.333 (+/-

0.034) fish-m-' at ST54, 0.496 (+/- 0.017) fish-m-' at GI94 and 0.029 (+/- 0.003) fish-m-' at 

GC18. 

Total fish abundance estimates from the platforms in this project summer within the 

range of estimates of fishes at platforms from our earlier research in the Gulf of Mexico but 

are higher than those derived by visual only surveys . Our earlier research found an average of 

12,473 (+/- 6,522, 95 % confidence interval) fishes at a site in 24m of water, while during this 

project estimates of the total number of fish per site were 13,472 (+/- 1,346) at ST54, 28,952 

(+/- 1,806) at GI94 and 13,856 (+/- 1,324) at GC18. One of the most interesting results of 

the project was the comparison of abundance between the sites. GC 18 was 3 to 10 times larger 

than the others but the total abundance estimates were not significantly different than the 

smallest site (ST54), while the abundance estimates from GI94 were twice that of the other 

sites. The low abundances observed at GC 18 are likely due to its location and water depth at 

the site . Fish abundance was essentially zero below 100 m and densities above 100 m were 

lower than those observed at the other sites. Because of the location of GC 18 it is not 

xx 
influenced by the eutrophic waters on the continental shelf and the outflow from the 

Mississippi river, it most influenced by oligotrophic oceanic waters from the Caribbean. The 

combination of water depth and oligotrophic conditions likely reduced the abundance of fishes 

around GC 18. 

In response to the use of platforms by fishers in the region Louisiana and Texas both 

created artificial reef programs where the materials of choice are retired platform jackets . The 

standard deployment of these structures as reefs involves placing the jacket on its side, 

however, this minimizes vertical relief. If a platform such as GC 18 was deployed in this 

manner it would extend approximately 80 m off the bottom. Based on our results at the site 

very few fishes would utilize the structure in this orientation and its value as an artificial reef 

would be questionable . This project is the first demonstrating the importance of vertical relief 

in maximizing the effectiveness of platforms as artificial reefs, especially with respect to deep 

water environments. 

This research confirms the variability of fish assemblages associated with petroleum 

platforms and reinforces the need to sample on each side and throughout the water column to 

obtain an accurate estimate of fish abundance . The high abundance of fishes found at the sites 

demonstrates the importance of petroleum platforms to the marine environment of the northern 

GOM. Although some variance was observed, 10,000 to 30,000 fishes were found per site at 

any one time and since over 1,000 platforms are located in similar water depths it is clear that 

these structures impact the fisheries of the region . 

This study continues to demonstrate the utility of merging hydroacoustics and visual 

survey techniques to study the assemblage of fishes associated with petroleum platforms . The 

combination of these techniques allows for the measurement of the area of influence of these 

defacto artificial reefs, as well as estimates of abundance, size distribution and species 

composition throughout the water column and over long time periods . 

xxt 

INTRODUCTION 

The largest artificial reef complex in the world, although unplanned, is composed of 

4,000 petroleum platforms scattered across the outer continental shelf (OCS) of the northern 

Gulf of Mexico (GOM). It is hypothesized that artificial reefs and platforms improve and/or 

diversify habitat, increase resources, modify the assemblages of organisms in the region or 

concentrate existing resources. The placement of these defacto reefs has undoubtedly impacted 

the regional marine community although little information is available. Only recently have 

assessment methods been developed to test these and other hypotheses concerning artificial 

reefs. 

Since the first petroleum platform was placed off the Louisiana coast in 1948, they have 

been the preferred destination of commercial and recreational anglers . Past research has found 

that platforms were the destination of 70% of all recreational angling trips in the Exclusive 

Economic Zone (more than 4.8 km from shore) (Reggio 1987) and 37% of all saltwater 

recreational angling trips off the Louisiana coast (Witzig 1986). The catch at these structures 

was estimated to constitute 30% of the recreational fisheries catch for the region (Avanti Inc . 

1991) . Results from a logbook program documented that 48 species were commonly caught 

and that catch rates of the target species, spotted seatrout and red snapper, averaged over 2 

fish/angler hour (Stanley and Wilson 1991). The high documented catch rates and popularity 

with user groups in the region make platforms an important component in the regions fisheries. 

Despite the number of sites, the time the structures have been present and their importance to 

the region's fisheries, little information exists on the assemblage of fishes associated with 

petroleum platforms. 

Scientific investigations of fish assemblages at petroleum platforms did not start until 

the mid 1970's . They consisted of visual surveys conducted by SCUBA divers, remotely 

operated underwater vehicles (ROV) and stationary cameras ; the majority of these projects 

were short term, often only "snapshots" of the fishes at each site (Shinn 1974, Sonnier et al . 

1976; Gallaway et al . 1981 ; Continental Shelf Associates 1982 ; Gallaway and Lewbel 1982; 

Putt 1982). The results of this early research provided insights into structure associated 

assemblages including variations in abundance and species composition with platform, water 

depth and time of the year. However, results have been difficult to compare due to problems 

with limited visibility, gear bias, diver avoidance and a lack of standardized survey 

methodology . Although visual surveys are the method of choice to survey natural and artificial 

reefs (Bortone and Kimmel 1991), the presence of SCUBA divers can bias the density and 

possibly species composition of fishes at the site (Sale and Douglas 1981 ; Brock 1982; 

Bohnsack and Bannerot 1986; Stanley and Wilson 1995) . 

In response to the difficulty in assessing the fisheries resources associated with 

petroleum platforms and the bias's inherent with visual surveys, Gerlotto et al . (1989) 

demonstrated that towed hydroacoustics could be used to measure fish density near petroleum 

platforms off Cameroon . We later utilized complimentary sampling methods of visual surveys 

and quantitative dual beam hydroacoustic surveys to document the assemblage of fishes 

1 
associated with petroleum platforms in the northern Gulf of Mexico (Wilson and Stanley 1991 ; 

Stanley and Wilson 1995, 1996, 1997). 

Despite the range of methodologies, investigators found that fish abundance and species 

composition change dramatically with proximity to platform, location, and time of year 

(Sonnier et al . 1976 ; Continental Shelf Associates 1982 ; Gallaway and Lewbel 1982; Putt 

1982 ; Stanley and Wilson 1996; 1997) . Gerlotto et al . (1989) found that fish densities were 5 

to 50 times higher immediately adjacent to a platform than 50 m away. Stanley and Wilson 

(1996, 1997) reported the near field area of influence of a platform on the continental shelf 

(water depth 25 m) to be 16 m away from the platform . Fish densities within 16 m of a 

platform were 3 to 25 times higher than at greater distances and densities observed at distances 

greater than 30 m were comparable to background levels of the open waters of the northern 

GOM. Long-term studies reported that fish populations at petroleum platforms were highly 

variable over time. Putt (1982) observed fluctuations of a factor of two from month to month 

in density. While Stanley and Wilson (1996, 199' reported that monthly and seasonal 

abundances change by up to a factor of five . 

Based on these previous research efforts, we know that significant numbers of fishes 

are found at these sites, although they do not exhibit a large species diversity and do not appear 

to have a high site fidelity . Since many of the common species at platforms are highly sought 

after by commercial and recreational users and there are a large number of platforms in the 

region, it is hypothesized that platforms they have considerable importance to regional 

fisheries. Despite this hypothesis of the importance of platforms on the regional fish 

assemblages, quantifiable censuses of fish assemblages were not possible until the combined 

use of dual beam hydroacoustics to enumerate the fishes at these sites and visual surveys with a 

remotely-operated underwater vehicle (ROV) to determine species composition were applied. 

While the results from previous research provided insights into the species composition and 

abundance at platforms the results are not comparable nor were they quantifiable . In order to 

measure the impact of the presence of platforms on the fisheries resources a standardized 

quantifiable methodology must be used . 

The reuse of petroleum platform jackets is becoming a common phenomena as both 

Louisiana and Texas have established state artificial reef programs and have used 

approximately 100 retired structures to date. With the success of the artificial reef programs in 

the Gulf of Mexico, other countries are actively exploring the potential use of retired platforms 

as artificial reefs . Despite the popularity and enthusiasm for the use of these structures as 

artificial reefs a number of questions remain regarding the practical value of retaining 

petroleum platforms as artificial reefs . Questions include the affect of water depth, geographic 

location, seasonal migrations and hypoxia on the platform associated fish assemblages. These 

issues need to be addressed to determine the effectiveness of these structures as artificial reefs 

and their impact on the marine ecosystem in the region . 

The specific objectives of this research were to: 

2 
1) Measure and compare the species composition, biomass and size frequency distribution of 

fish associated with three petroleum structures . It has been proposed that fish communities 

around oil and gas platforms vary with platform size and water depth. Therefore it may be 

inappropriate to extrapolate results from one depth to others . Despite the possibility of alongshelf differences, a comprehensive description of the platform associated fish communities at 

different depths will improve our understanding of these environments. 

2) Determine the effect of temporal, physical and chemical variables on species composition, 

biomass and size distribution of fish associated with platforms . If reef fish are habitat limited 

then fish biomass should increase with platform size . In addition, if our results from WC352 

hold true, biomass and size distribution should change over diel and seasonal periods. 

3) Define the spatial near field influence of each platform on the abundance of fish . It is 

critical to have a measure of the near field of influence of a platform in order to accurately 

estimate the associated fish population . Estimates of platform specific fields of influence will 

allow us to covert measured densities into area estimates of fish densities . 

4) Document the near field behavior patterns of fish around each platform. What behavioral 

patterns can be inferred by the diel and seasonal movements of fish around oil and gas 

platforms? Insight into this movement may help us better understand the influence that 

platforms have on fish communities and enable us to predict how future oil and gas activity 

will affect these populations . 

3 

METHODS 

This research project was designed to effectively sample platforms in three water depths 

(shallow continental shelf, mid continental shelf, continental slope, Figure 1), across the 

Louisiana shelf during the four seasons (spring, summer, fall, and winter) . Based on our 

previous research, a sampling regime of five days at each platform were required per site . 

Transport logistics limited us to a minimum of one week between sites, therefore the project 

was designed, and constrained to, twelve sampling events (four per site), during a project year. 

Site Descriptions 

Research trips were conducted quarterly (August 1994 to April 199' to petroleum 

platforms Grand Isle 94 (GI94) (located at 28°31 .33 N and 90°05.52 W, water depth 60 m, 

installed 1975, operated by Mobil USA Inc.) and Green Canyon 18 (GC18) (located 27°56.48' 

N and 91°02 .28' W, water depth 219 m, installed in 1988, operated by Mobil USA Inc.) and 

quarterly (August 1995 and April 1997) to South Timbalier 54 G (ST54) (located 28°50.01'N 

and 90°22.40' W, water depth 22m, installed 1956, operated by Exxon USA Inc .) . The 

platforms were selected to approximate a transect extending from Fourchon LA ; ST54 was 24 

km southwest from port ; GI94 was 54 km south ; GC 18 was 179 km southwest (Figure 1) . 

ST54 and GI94 were eight pile production platforms while GC 18 was a large six pile 

production platform . Extraction and production of natural gas and crude oil occurred at each 

site and research activities were scheduled to minimize our impact on regular platform 

operations . Three research trips could not be completed during the project including spring 

1995 trips to GI94 and GC 18 due to lightening damage to the hydroacoustic equipment and the 

fall 1996 research trip to ST54 due to activities on the platform which Exxon USA Inc. 

deemed dangerous and denied access to the platform for research purposes over that period . 

Three arrays of stationary dual beam hydroacoustic equipment developed through our 

past research were used to determine the density of fishes associated with the study sites 

(Wilson and Stanley 1991 ; Stanley and Wilson 1995, 1996, 1997,1998, in press) . Arrays 1 

and 2 (Figure 2) were designed to measure in situ target strength distribution and density of 

fishes immediately adjacent to each side of the platform . Array 1 consisted of four upward 

oriented transducers (120 kHz) suspended approximately 25 m below the surface (at ST 54 

they were placed on the bottom), one on each side of the platform . The upward facing 

transducers provided acoustic coverage from the a depth of 10-15 m to the surface (Figure 2) . 

Array 2 consisted of four downward oriented transducers (120 kHz) placed approximately 3 m 

below the surface, one on each side of the platform . The downward facing transducers 

provided acoustic coverage from a depth of 10 m to within 1 - 5 m of the substrate depending 

on the site . The use of four transducers (both upward and downward orientations) enables the 

calculation of density throughout the water column on all sides of the platform. 

Array 3 was designed to estimate the near field density of fishes associated with the 

structure and consisted of four horizontally aligned dual beam transducers (120 kHz) deployed 

off each side of the platform at depth of 12 m (Figure 3). This arrangement enables relative 

5 
fish density estimates to a distance of approximately 80 m from the platform and determination 

of the near field area of influence of each site . 

Total fish abundance estimates at each site were calculated by determining the nearfield area of influence of the platform, then multiplying mean density values for sample and 

platform side, in number of fish/m3, by the volume of water on each side of the platform . Fish 

density in the center of the platform was calculated by averaging the density estimates of the 

four sides of the platform. Fish abundance in the center of the platform was calculated by 

multiplying the estimated fish density at the center by the volume of water in the center of the 

platform. After estimates of the number of fish were estimated on each side and center of the 

structure by strata these estimates were summed to calculate the total number of fishes at a site . 

Horizontal and vertical acoustic sampling were conducted over three consecutive 24 

hour intervals for each month's sampling trip ; two hours of hydroacoustic data were collected 

encompassing four periods (dawn, noon, dusk and midnight) over each 24 hour interval . 

Hydroacoustic data were collected sequentially from each of the transducers in five minute 

intervals for each trip . 

Acoustic data were collected using a Biosonics model ES2000 scientific 

echosounder/multiplexer-equalizer . The source levels ranged from 218 .5 to 220 .5 dB re ,"Pa 

at 1 m depending on the transducer . The 20 log R system gains ranged from -156.4 to -146.8 

dB re V kcPa and the 40 log R system gains ranged from -168 .9 to -165 .8 dB re V uPa varying 

with transducer . Sampling rate ranged from 2 pings s' to 10 pings s' depending on array and 

sampling depth . Pulse width was 0.4 ms. Received signals were adjusted for spreading loss 

by applying a 40 log R time varied gain, digitized and recorded on digital audio tape (DAT). 

Reference voltages (approximately 5 V AC) were recorded on each DAT tape and used to 

calibrate the acoustic system prior to echo integration and target strength analyses . During 

data collection background noise levels were measured and did not exceed 40 mV. The 

voltage threshold used in later analyses was 100 mV corresponding to a minimum detectable 

target strength of -56 dB, or a fish of 2.5 cm total length according to Love (1971) . 

Digitized hydroacoustic data were processed by a Biosonics model 281 dual-beam 

processor. Target strengths and an average backscattering cross section (a) for each depth 

strata were estimated using Biosonics TS software, and density estimates were calculated using 

Biosonics Crunch software with a for each sample and depth strata . Fish densities were 

calculated for 5 to 20 m depth vertical intervals for Array 1 and 2 depending on site . 

Visual point count surveys were performed on each sampling expedition on the 

downcunent side of the platform using a Hydrobotics Orpheus, Benthos MiniRover, or Deep 

Ocean Engineering HD2 ROV. Visual surveys were performed on nektonic fishes freely 

swimming within the area of influence of the platform . Cryptic fishes were not included in the 

visual surveys since they could not be assessed in the acoustic surveys . Visual surveys done 

with ROV's were recorded on videocassette and the point counts performed later identifying 

individual fish to the lowest taxonomic level . Estimates of percent species composition for 

each strata corresponding to the acoustic strata were calculated from the visual point counts . 

6 
To estimate the number fishes by species at each site by depth strata the percent species 

composition data was applied to the quantitative acoustic estimates of total abundance and 

confidence intervals for each strata from every sampling trip . 

Environmental data consisting of temperature (+/- 0.1 °C), salinity (+/- 0.1 ppt) and 

dissolved oxygen (+/- 0 .5 ppm) were measured with a Seabird SBE 19 meter. Current speed 

(+/- 0.1 m/s) and direction (+/- 1 degree) were measured an Interocean S4 meter during each 

hydroacoustic data collection period through the entire water column at each site . 

Data Analysis 

Fish density data (number of fish-m-') from echo integration analysis contained a large 

number of zero values, similar to catch data from traditional fisheries sampling techniques 

(Pennington 1983; 1985 ; Shaw et al . 1985; Stanley and Wilson 1995; 1996; 1997) . Therefore, 

hydroacoustic density data were transformed by log(density + 1) to approximate the normal 

distribution . 

Two vectors describing current speed and direction to the east-west and north-south 

were calculated (Pond and Pickard 1982). Currents from the east and north were scaled to 

positive values ; west and south currents were scaled to negative values . This scaling provided 

two vectors which represented current speed and direction in later analyses . 

Randomized block ANOVA's (SAS Institute Incorporated 1986) were performed for 

each site with horizontal log(density + 1) of density data on distance from the platform, time 

of day (TOD), quarter, year and their interactions, blocking on side of the platform to examine 

differences due to these variables . Tukey's studentized range tests (Ott 1982) were used to 

compare the means of significant variables for horizontal analyses . Statistical tests were 

reported as significant at the alpha < 0.01 level. 

Separate randomized block ANOVA's using SAS (1986) GLM procedures were 

performed with vertical target strength data and log(density + 1) of vertical density data for 

each site on depth, time of day, quarter, year, temperature, dissolved oxygen level, east and 

north current vectors, squared east and squared north current vectors and their interactions, 

blocking on side of the platform to examine differences due to these variables . Tukey's 

studentized range tests (Ott 1982) were used to compare the means of significant variables for 

vertical and horizontal analyses . Tests were reported as significant at the alpha < 0.01 level. 

The total abundance estimates at the platform were calculated by determining the nearfield area of influence of the platform, then multiplying mean density values (number of fish-m-

') for each month and platform side by the volume of water on each side of the platform. Fish 

density in the center of the platform, not measured with acoustics due to interference by 

structural members, was assumed to be the average of the density estimates of the four sides of 

the platform. Fish abundance in the center of the platform was calculated by multiplying the 

estimated fish density of the center by the volume of water in the center of the platform . 

7 

RESULTS 

South Timbalier 54 

Vertical Density Distribution 

Densities of fishes at the ST54 production platform (water depth 22 m) were highly 

variable over the study period ranging from 0 to over 5 .2 fish/m3 . A RBD ANOVA with 

platform side as a block was used to examine differences in density due to year, season, time 

of day, current vectors, temperature, dissolved oxygen, depth and selected interactions . 

Density varied significantly with season, time of day, depth, platform side, east current vector, 

north squared current vector, salinity, dissolved oxygen and the time of day * depth interaction 

(Table 1) . 

Temporal differences in fish density were detected between season, time of day and the 

interaction of season *time of day (Table 1, Figure 4). Fish density was highest in 1995 and 

1997 (although only one research trip occurred in 1997) indicating annual variation in the fish 

density at the site (Table 1) . Seasonally, fish densities were significantly higher in the fall than 

all other seasons and lowest densities found in the spring and summer (Figure 5). No overall 

trend of fish densities with season and time of day could be detected over the entire study 

period but overall fish densities were significantly higher at midnight than all other times 

(Figure 6) . 

Spatially fish density varied with platform side, depth and the interactions of depth*time 

of day and depth*season . Significantly higher densities were found on the north side of the 

platform than all others (Figure 7) . With respect to depth, densities were significantly higher 

in the upper 10 m of the water column than all other depth strata, although an increase in 

density from 20-22 m was observed when dissolved oxygen levels were greater than 3 ppm 

(Figure 8) . While the interaction of depth*time of day was significant (Table 1) in the overall 

model, examination of fish density by depth with time of day did not reveal an overall trend 

with exception of higher fish densities in the upper 10 m regardless of time of day. The 

interaction of depth*season was also significant and examination of density values by depth for 

each season revealed significantly lower densities in the spring and summer from 20-22 m than 

in the fall and winter . This difference is likely due to the low oxygen conditions found near 

the bottom during these periods . 

Environmental conditions also impacted density based on results from the RBD 

ANOVA (Table 1) . Fish density was significantly affected by temperature, dissolved oxygen, 

east current vector and the north current vector squared (Table 1) . Fish density decreased 

slightly with temperature although this is inconsistent with highest observed densities were 

from the fall and winter seasons when temperatures were lowest (Appendix 1) . A direct 

relationship between dissolved oxygen and density existed ; highest densities were found at high 

levels of dissolved oxygen. During the summer 1996 sample a hypoxic event was noted and 

dissolved oxygen levels were < 1 ppm below 15 m. Along with these low dissolved oxygen 

levels, fish density was essentially zero from 15-22 m, but higher than average densities were 

9 
detected from 0-10 m (Figure 9) . The relationship between current speed and fish density, 

while significant (Table 1), was difficult to interpret. Fish density generally increased with 

increasing current speed although the maximum current speeds observed were 43 cm/s. Since 

the mean current speed was 11 .3 cm/s, the majority of the speeds observed were likely not 

high enough to influence the behavior of the fishes as the mean size of the fishes was 

sufficient to negate the influence of low observed currents . 

Horizontal Density Distribution 

Horizontal density of fishes varied temporally and spatially at the platform . Spatially, 

horizontal fish density varied with side of the platform and distance from the platform (Table 

2). Fish densities were significantly higher in the 2-10 and 10-18m strata than all others 

(Figure 10). At distances from 18-82 m fish densities were at only half of those nearer to the 

platform (Figure 10) . Temporally, horizontal fish density varied significantly between years, 

seasons and time of day reinforcing the temporal variation observed with the vertically oriented 

transducer arrays (Table 2) . Annual variation in horizontal density revealed highest horizontal 

density in 1995 and lowest in 1997, while seasonally highest densities were found in the fall 

with all other seasons not being significantly different (Table 2) . Within a 24 hour period 

significantly higher densities were found at noon, while all other times were not significantly 

different (Table 2). 

Horizontal fish densities were used to measure the near field area of influence of the 

platform . Based on the decrease in fish density with distance from the platform the near field 

area of influence was estimated at 18 m (Table 2, Figure 10) . Beyond 18 m fish densities 

dropped off significantly and fish densities were not significantly different from 18 to 84 m 

(Figure 10). 

Estimated Number of Fish and Species Composition 

Examination of visual survey results revealed interesting and consistent trends in 

species composition with respect to depth, season and the dominance of a few species over the 

sample period (Table 3 a-g). A total of sixteen species were detected by the ROV during 

visual surveys but six species including Atlantic spadefish, bluefish, blue runner, mangrove 

snapper, red snapper and sheepshead consistently comprised over 95 % of the fishes 

enumerated at the site (Table 3a-g). Less commonly observed species included seasonal 

migrants detected in warmer periods ; barracuda, Bermuda chub, cobia and tarpon and species 

found during cooler water periods ; Florida pompano and red drum (Table 3 a-f) . 

During all surveys planktivores were numerically dominant and the most common 

species observed were Atlantic spadefish and blue runners (Table 3a-fl . These species 

typically constituted over 55 % of the fishes surveyed (Table 3g) and either species was the 

most numerically dominant depending on season . Blue runners were generally more abundant 

in the warmer surveys with the exception of the summer of 1996 when they were absent from 

the survey (Table 3e, Figure 11). A possible cause for their absence was the presence of a 

hypoxic event when depressed dissolved oxygen conditions were found in the lower 12m of the 

10 
water column (Appendix 1) . During the hypoxic event there was a complete absence of fish 

below 15m. Dissolved oxygen levels from 15 - 22 m were less than 0.2 ppm while from 10 -

15 m dissolved oxygen levels were < 3 ppm; only a few red snapper were detected in this 

strata . 

Depth also played an important role in the distribution of species at ST54 and consistent 

trends were observed with respect to the presence of species and depth (Table 3a-g). 

Examination of the depth distribution of the six most abundant species showed that Atlantic 

spadefish and bluefish were found in the upper water column, mangrove snapper and 

sheepshead were found throughout the water column but were most common at mid-depth, red 

snapper were most abundant in the lower 7 m of the water column and only blue runner were 

found evenly throughout the water column (Table 3g) . Trends in depth distribution of the less 

common species show that barracuda, Florida pompano and red drum were most common near 

the bottom while cobia, gray triggerfish, jack crevelle, lookdown, and tarpon were observed 

throughout the water column (Table 3g). 

Seasonal trends in species composition and depth distribution were also observed at 

ST54. During the winter sampling trips bluefish abundance was highest and they were found 

at mid-depth, blue runners were uncommon and although overall Atlantic spadefish abundance 

did not change they were found throughout the water column in contrast to their abundance 

near the surface during other sampling periods (Table 3a-fl. During warmer sampling periods 

blue runner and mangrove snapper were more common and generally found in the upper water 

column (Table 3a-f) . 

Extrapolating the species composition estimates with the acoustic abundance data for 

each depth strata provided estimates of individual species abundance throughout the water 

column (Table 4, Figure 12). By species, Atlantic spadefish or blue runners were the most 

abundant fish at ST54 with the exception of the spring and summer 1996 samples when 

mangrove snapper abundance was slightly higher (Table 4a-fl. Large fluctuations of 3-5 fold , 

by species was detected between samples (Table 4a-f, Figure 12) . The species exhibiting the 

largest change over the sample period was mangrove snapper with abundances changing from 

an approximately 80 individuals in the summer of 1995 to approximately 4000 in the fall, then 

dropping to an estimated 90 fish in the Winter of 1996 and increasing to 2900 in the Spring of 

1996 (Table 4a-d). Large fluctuations in abundance by species over time was observed and an 

example was the presence of over 2400 bluefish in the winter 1996 sample while at other times 

of the year this species was absent (Table Sa - f, Figure 12). With the exception of mangrove 

snapper the only recreationally and commercially important species that was abundant at ST54 

were red snapper, other highly sought after species were generally rare (Table 4a-fl . 

The mean abundance, with 95 % confidence intervals, of fishes at ST54 by sample was 

variable with a low of 7159 (+/- 993) fish at in the summer of 1995 and a high of 28553 (+/-

6141) fish in the fall of 1995 (Table 4a-fl . Averaged over all the sample periods there were 

13472 (+/- 1347) fish at the site (Table 4g) . By depth 58% of the fishes were found in the 

upper 10 m of the water column with the lowest abundance of fish found adjacent to the 

substrate (Table 4g) . 

11 
Grand Isle 94 

Vertical Density Distribution 

Densities of fishes at the GI94 production platform (60 m depth) were variable over the 

study period ranging from 0 to over 1 .1 fish/m3 . A RBD ANOVA with platform side as a 

block was used to examine differences in density due to year, season, time of day, current 

vectors, temperature, dissolved oxygen, depth and selected interactions . Density varied 

significantly with year, season, time of day, depth, platform side, north current vector, east 

squared current vector, dissolved oxygen and temperature (Table 5) . 

Temporal differences in fish density were detected between year, season and time of 

day (Table 5). Fish density was significantly different between all years examined with 

significantly higher densities observed in 1997 than all other years, although only one research 

trip occurred in 1997 (Figure 4). The lowest annual densities were found in 1996 with 1994 

and 1995 having significantly higher annual densities (Figure 4, Table 5) . Seasonally, fish 

densities were significantly higher in the winter followed by fall then spring, and lowest in the 

summer (Figure 3, Table 5) . Mean densities in the winter and fall were on average five to ten 

times higher than in the spring and summer (Figure 5). While fish densities varied with time 

of day and were significantly different (Table 5), the differences were much smaller than any 

other temporal variable examined (Figure 6) . Highest densities were found at dawn and 

significantly lower densities were detected at dusk, otherwise densities were not significantly 

different (Figure 6) . 

Spatially, fish density varied with platform side and depth (Table 5) . Significantly 

higher densities were found on the north and west side than on the others (Figure 7) . Lowest 

densities were found on the east side of the platform (Table 5) . Densities varied significantly 

with depth, with lowest densities were found from 5 - 20 m and highest near the surface and 

bottom (Figure 8) . Significantly higher densities were found immediately above the bottom 

(water depth 50 - 55 m) than at all other depth strata (Figure 8) . Other regions of high 

densities included 0 - 5 m and 40 - 60 m (Table 6, Figure 8) . 

Results from the RBD ANOVA of environmental variables showed significant impact 

on fish density due to temperature, dissolved oxygen, north current vector and the east current 

vector squared (Table 5) . Fish density decreased slightly with temperature although this is in 

conflict to the highest observed overall densities which occurred in the fall and winter when 

temperatures are the lowest (Figure 5) and highest observed densities from 40 - 60 m where 

temperatures were generally lowest (Figure 8, Appendix 2) . A positive relationship was 

detected between dissolved oxygen and density as density increased with increasing dissolved 

oxygen levels although hypoxic conditions were not observed at GI94 . The lowest dissolved 

oxygen levels were found were 4.4 ppm (Appendix 2) . This is the likely explanation for the 

positive relationship between dissolved oxygen and density since hypoxia was not an issue at 

GI94 (Appendix 2, Figure 8) . The ANOVA results indicated a positive relationship between 

current speed and fish density (Table 5). While the relationship showed and an increase in 

12 
density with decreasing current speed, less than 5 % of the current observations exceeded 20 

cm/s, with mean current speed of 10.0 cm/s and the maximum observed current speed was 

39 .6 cm/s (Appendix 2) . Because of the low number of high current speed observations it is 

more plausible that the high densities observed at low current speeds were due to depth; the 

highest densities were found from 40 - 60 m where current speeds were typically the lowest 

(Figure 8, Appendix 2) . Due to the relatively large size of the fishes observed at the site it is 

probable that the current speeds observed were not great enough to influence the behavior of 

the fishes . 

Horizontal Density Distribution 

Horizontal density of fishes varied temporally and spatially at the platform (Table 6). 

Spatially, horizontal fish density varied with side of the platform and distance from the 

platform while temporal variation was observed with year and season (Table 6) . The 

interactions of time of day and distance from the platform, season and time of day and time of 

day and distance from the site were also significant (Table 6) . The spatial relationship of 

horizontal density differing with side of the platform reinforced a similar relationship observed 

in the significant change in fish density between sides also observed in the vertical density 

distributions (Figures 8 and Table 6). With respect to side, the horizontal results were similar 

to the vertical density results. Highest densities were found on the north, west and south sides 

for both transducer arrays (Table 6, Figure 7) . 

The close association of fishes with platforms observed at shallower depths was not 

observed at GI94 (Figure 10). Relative fish density was significantly higher from 0 - 58 m 

away from the site than at all other distances examined (Figure 10). Lowest observed densities 

were at distances greater than 58 m from the site and beyond 58 m fish densities were similar 

to those acoustically measured in the open waters of the northen Gulf of Mexico (Figure 10). 

Temporally, variation in relative density was found with year and season . Again, the 

temporal horizontal density results were similar to the vertical results with significantly higher 

densities were found in 1997 and 1995 as compared to 1994 and 1996 (Table 6, Figure 4) . 

With respect to season highest densities were found in the winter and fall for densities 

measured with both horizontal and vertical transducer arrays (Table 6, Figure 6) . The 

significant interaction terms of distance and season, time of day and distance and season and 

time of day emphasize the variability in the density of fishes associated with the site . 

Horizontal fish densities were used to measure the near-field area of influence of the 

platform . The highest horizontal densities measurements were from 0-18 m, but these 

densities were not significantly higher than those from 18-58 m (Figure 10) . Despite the 

measurement of high relative densities from 18 to 58 m at GI94, we estimated the near field 

area of influence at 18 m, while the relationship of fish density with distance from the site was 

difficult to resolve, we feel that a conservative area of influence of 18 m best reflects a true 

population size of the fishes at the site (Table 6, Figure 10) . The increased water clarity and 

pelagic species composition at G194 likely increased distance the fishes ranged from the site. 

However, based on the visual data from the ROV, 18 m best reflects the distance fishes 

13 
typically ranged from the site based on the visual observations . Beyond 58 m the relative fish 

densities measured at GI94 decreased dramatically to levels found at other sites (Figure 10) . 

Estimated Number of Fish and Species Composition 

Examination of visual survey results demonstrated interesting trends in species 

composition with respect to depth, season and the dominance of one species over the sample 

period (Table 7 a-k) . A total of twenty-four species were detected by the ROV during visual 

surveys but one species, blue runner, comprised on average 87% of all observed fishes (Table 

8k) . By grouping blue runners with the next five most abundant species, horseeye jack, red 

snapper, mangrove snapper gray triggerfish and barracuda, over 95 % of the fishes observed at 

the site were accounted for (Table 7a-k). Uncommon species at the platform included bigeye, 

black grouper, cobia, gag grouper, ocean triggerfish, rainbow runner, vermillion snapper and 

yellowfin grouper (Table 7a-k) . 

Seasonality in the abundance of fishes was detected at GI94 with cobia, red snapper, 

almaco jack and amberjack more common in the spring and summer than during cooler periods 

(Table 7a j) . During fall and winter we found an increase in the abundance of barracuda and 

blue runner (Table 7a j). Blue runners exhibited the most dramatic seasonality . Few were 

found during summer samples when they constituted < 30% of the fishes observed, however 

during fall, winter and spring samples blue runners were the dominant fish observed and 

composed 71 to 94 % of the fishes found at the site (Table 7a j) . While most other species 

were found at a relatively narrow depth range, blue runners were found throughout the water 

column, although they were slightly more abundant near the surface (Table 7a-k) . Fishes with 

higher abundance from mid depth to the bottom included greater amberjack, red snapper and 

scamp (Table 7a-k) . Surface oriented species included bar jack, Bermuda chub and rainbow 

runner while species found throughout the water column included almaco jack, barracuda, gray 

triggerfish, horseeye jack, jack crevelle, and mangrove snapper (Table 7a j) . 

Extrapolating the species composition estimates with the acoustic abundance data for 

each depth strata provided estimates of individual species abundance throughout the water 

column (Table 8a-k) . The total number of fish at the GI94 ranged from a low of 2,380 (+/-

740, 95% confidence interval, Table 8g, Figure 12) during the Spring 1996 sample period to a 

high of 67,027 (+/- 4,696, Table 8j, Figure 12) during the Winter 1997 period with a mean of 

28,952 (+/- 1,806) fishes averaged over all the sample periods. The seven most abundant 

species (highest to lowest) were blue runner, red snapper, horseeye jack, mangrove snapper, 

greater amberjack, barracuda and grey triggerfish (Table 8k) . Blue runner dominated the 

number of fishes observed at the site with an average of 25,188 (+/- 1571, 95 % confidence 

interval) . Their abundance was highly variable with a low of 2,242 (+/- 698) observed in the 

Spring 1996 sample (Table 8g, Figure 11) to a high of 62,335 (+/-4,367) from the Winter 

1997 sample (Table 8j, Figure 11). The estimated number of blue runner was also variable 

with a five to sixfold change in abundance was observed from the Fall of 1994 to Spring 1995 

(Table 8b-d, Figure 11) . Generally, their abundance would peak in fall or winter and then 

drop during other surveys (Figure 11). 

14 
The abundance of greater amberjack, horseeye jack, mangrove snapper, and red 

snapper was typically highest in fall and winter and lower during spring and summer samples 

(Figure 13), although the second highest number of red snapper observed over the study period 

was found during the summer 1994 research trip . Significant changes in the abundance of 

other individual species were also noted. Three to fivefold differences in estimated abundance 

between sample periods were common for greater amberjack, horseeye jack, mangrove 

snapper, and red snapper (Figure 13) . 

Green Canyon 18 

Vertical Density Distribution 

Densities of fishes at the GC 18 production platform (water depth 219 m) were variable 

over the study period ranging from 0 to over 1 .44 fish/m3 . A RBD ANOVA with platform side 

as a block was used to examine for differences in density due to year, season, time of day, 

current vectors, temperature, dissolved oxygen, depth and selected interactions . Density 

varied significantly with platform side, season, depth, north current vector squared and the 

interactions of time of day and depth and season and depth (Table 9) . 

The only significant temporal differences in fish density were detected with season and 

the interaction between depth and time of day (Table 9). Seasonally, fish densities were 

significantly higher in the winter and summer than the fall and spring (Figure 5, Table 9) . 

Mean densities in the winter and summer were on average two to five times higher than in the 

spring and fall (Figure 5) . Other differences observed in temporal variables examined (e.g., 

year and time of day) were not significant (Table 9, Figures 4 and 6). 

Spatially, fish density varied with platform side and depth (Table 9) . Significantly 

higher densities were found on the west side of the platform than at all others, and densities 

were not significantly different on the north and south sides (Figure 7) . Densities on the east 

side were five to eight times lower than those on other sides of the platform (Table 9, Figure 

7) . The most dramatic results of the research project was the relationship between fish density 

and depth at GC18. A significant and spectacular drop in density with depth was observed at 

GC 18 below 100 m (Table 9, Figure 14). Fish densities from 0 - 15 m were significantly 

higher than all other depth strata and were 4 to 68 times higher than all other depths (Figure 

14) . Densities from 15 to 95 m were not significantly different but were 3 to 12 times higher 

than depths from 115 to 210 m (Figure 14). From 115 to 210 m fish density was less than 

0.002 fish/m3, essentially zero, and lower than densities in the open waters of the Gulf of 

Mexico on the continental shelf (Figure 14) . 

Environmental conditions did little to impact fish density at GC 18 based on results from 

the RBD ANOVA (Table 9) . Fish density was significantly affected only by the north current 

vector squared, although temperature and dissolved oxygen were close to significant with a 

probability of a greater F of 0.0206 and 0.0283, respectively (Table 9) . There was an inverse 

relationship between fish density and north vector squared as fish density decreased slightly as 

15 
north vector squared increased . This decrease is likely due to observations from the summer 

1995 sample when relatively high current speeds with a northerly component were found 

(Appendix 3). The close to significant relationship between density and temperature is likely 

correlated to the significant seasonal relationship documented earlier (Table 9, Figure 5) with 

highest densities found in the winter, although this relationship is confounded by the low 

densities at depths where temperatures were lowest (Figure 14, Appendix 3) . The observation 

of declining density with low dissolved oxygen levels is probably due to the low fish densities 

observed below 95 m where dissolved oxygen levels were lowest (Table 9, Figure 14, 

Appendix 3) . However, no hypoxic events where detected at GC 18 (Appendix 3) . 

Horizontal Density Distribution 

Horizontal density of fishes varied temporally and spatially at the platform (Table 10) . 

Spatially, horizontal fish density varied with side of the platform and distance from the 

platform . Temporal variation was observed with season, time of day and the interactions of 

time of day and distance from the platform (Table 10) . 

The differences in fish density with side of the platform observed with the horizontally 

oriented transducers reinforces the observed variation in fish density with platform side from 

the vertically oriented arrays (Figure 7, Table 10). The close spatial association of fishes with 

platforms at sites on the continental shelf (e .g ., ST54) was more evident at GC18 than GI94 

(Figure 10) . Fish density was significantly higher from 2-10 m away from the site than at all 

other distances examined (Figure 10). Densities from 10-42 m were not significantly different 

from each other and lowest observed densities were from 50 - 82 m from the site (Figure 10) . 

Temporally, the variation in horizontal fish density was found with respect to season is 

similar to the variation in fish density with season observed from the vertical density arrays 

(Table 9 and 10) . Diel variation was observed in the horizontal density of fish with highest 

densities found at noon (Table 10). This was the only case during this research project where 

diel variation was observed, and because e it was not observed with the vertical transducer 

array it is presumably due to off site behavior of fishes in the upper water column since the 

maximum deployment depth of the horizontal transducers was 13 m and would not reflect 

behavior of fishes throughout the water column. 

Horizontal densities were used to measure the near-field area of influence of the 

platform . Densities were significantly higher within 10 m of the site, and while densities from 

10-42 m were high we feel that a conservative area of influence of 10 m best reflects a true 

population size of the fishes at the site (Table 10, Figure 10). Beyond 50 m the relative fish 

densities measured at GC18 decreased dramatically to levels found in the open shelf waters of 

the Gulf of Mexico (Figure 10) . 

Estimated Number of Fish and Species Composition 

Examination of visual survey results revealed a fairly stable species assemblage at the 

site with interesting and consistent trends in species composition with respect to depth, season 

16 
and the dominance of a few species over the sample period (Table 11 a-1) . A total of eighteen 

species were detected by the ROV during visual surveys but six species including creolefish, 

blue runner, Bermuda chub, almaco jack, amberjack, and barracuda consistently comprised 

over 90% of the fishes enumerated at the site (Table 11 a-1) . Other species observed included 

bar jack, blackjack, blackfin tuna, grey triggerfish, horseeye jack, lesser amberjack, marbled 

grouper, ocean triggerfish, rainbow runner, scamp and yellowtail snapper. Due to their 

scarcity it is difficult to discern any seasonal patterns (Table 11 a-1) . 

Creolefish was the most common species enumerated at GC 18 ranging from a 

maximum of 67% of the fishes detected in the summer of 1995 (Table 11 e) to a minimum of 

40% in the winter of 1995 (Table 11 c) and on average they made up 50% of the fishes 

observed (Table 121) . With respect to depth, creolefish were concentrated in the mid to upper 

water column with approximately 90% of the individuals found above 60 m (Table 11 a-1) . 

Seasonally, no consistent trends in creolefish abundance were found although their numbers 

tended to increase during fall and winter surveys (Table l la-k). The next most common 

species detected was usually blue runner (Table 11 d-k) making up an average of 20 .5% of the 

fishes (Table 111) . However, during the fall 1994 sample blue runners were absent (Table 

l lb) and during the winter 1995 survey they made up less than 5 % of the fishes observed 

(Table l lc) . After creolefish and blue runner, no other species observed made up more than 

10% of the fishes at GC18 . The next most commonly observed species were Bermuda chub, 

almaco jack, greater amberjack and barracuda (Table 11) and while Bermuda drub typically 

were the third most abundant species observed there was a large amount of fluctuation in the 

fourth through sixth positions (Table l la - j) . Within these species it was difficult to discern 

any seasonal patterns with the exception of barracuda as their presence increased during cooler 

periods (Table l la j) . With respect to depth barracuda and Bermuda drub were predominately 

found above 40 m (Table 11 a -j) . Almaco jack were found from the surface to 160 m but 

approximately 90% of these fishes were found from 40 to 100 m (Table 11 a - j) . Greater 

amberjack were almost exclusively found from 40 to 100 m with few observed outside of this 

depth range (Table l la - j) . 

The ROV survey results below 100 m supported the acoustic findings with an almost a 

complete lack of fishes (a total of 38 fishes of 4 species) were observed in eleven surveys 

below 100 m (Table 11 a- 1) . Almaco jacks showed the widest depth range of any of the fishes 

observed at GC18 as they were common from the surface to mid depth and one of the few 

fishes found below 100 m (Table 11 a-1) . Typically, most species exhibited a specific depth 

range and were less frequently found outside that range. Surface oriented species included bar 

jack, barracuda, Bermuda drub, blue runner and horseeye jack (Table l la-k) . Species 

common from 20 to 60 m included blackjack, blackfin tuna, creolefish, grey triggerfish, 

rainbow runner and yellowtail snapper (Table 11 a-k) . Species commonly found from 60 to 

100 m were almaco jack, greater amberjack and scamp, although as previously mentioned 

almaco jack had the widest depth range of any of the observed species (Table 1 la-k). 

Extrapolating the acoustic abundance data using the species composition estimates for 

each depth strata provided estimates of individual species abundance throughout the water 

column (Table 12 a-k) . The total number of fish at the site ranged from a low of 8,321 (+/-

3,470, 95% CI, Table 12g) during the spring 1996 sample to a high of 21,767 (+/- 4,655, 

17 
Table 12k) during the winter 1997 sample . Averaged over all sample periods 13,855 (+/-

1,206) fishes were found at GC18 and the six most abundant species (highest to lowest) were 

creolefish, blue runner, Bermuda chub, almaco jack, greater amberjack and barracuda (Table 

12k). Creolefish dominated the observed fishes at the site . An average of 4,924 (+/- 445) 

were estimated at GC 18 over the study period which was twice as abundant as any other 

species on average (Table 12k, Figure 15). The next most abundant species was blue runner 

(Table 12 a-k, Figure 11) . As with the other sites the abundance of blue runner was variable 

over the study period ranging from a high of 8,962 in the summer 1994 (Table 12a) to a low of 

0 during the Fall 1994 survey (Table 12b). After the initial variability during the summer and 

fall 1994 surveys, blue runner abundance appeared to level off and the earlier heterogeneity 

decreased (Table 12a - j, Figure 11) . 

Examination of the abundance of other dominant species over the study period showed 

large changes in the abundance of amberjack, almaco jack and Bermuda chub between sample 

periods (Table 12 a -j, Figure 15). The only dominant species that did not undergo extreme 

changes in abundance over time was barracuda, however a twofold decrease in abundance was 

observed from spring 1996 to summer 1996 samples (Table 12 a -j, Figure 15) . With respect 

to a seasonal pattern in abundance, highest numbers of amberjack and almaco jack were 

consistently found in the fall and winter surveys while Bermuda chub estimates were highest 

during spring and summer surveys (Table 12 a -j, Figure 15) . Barracuda estimates, as pointed 

out earlier, were much more stable than the other dominant species but their abundance was 

typically higher in the cooler sampling periods (Table 12 a -j, Figure 15) . 

18 
South Timbalier 54 

Target Strength Distribution 

The target strengths of the fishes at the ST54 production platform were variable over 

the study period and a RBD ANOVA with platform side as a block was used to test for 

differences in target strength due to year, season, time of day, current vectors, temperature, 

dissolved oxygen, depth and selected interactions . Target strength varied significantly with 

season, time of day, depth, platform side, temperature, east current vector, north current 

vector, north squared current vector, east squared current vector, and the interaction terms 

(Table 13) . 

Temporal differences in target strength were detected between season, time of day and 

the interaction of season and time of day (Table 13) . Seasonally target strengths were 

significantly larger in summer, decreased in spring and winter and lowest in the fall (Table 

14) . Two groupings of target strength with time of day were found with largest target 

strengths in the dawn and noon samples and significantly smaller target strengths in dusk and 

midnight samples (Table 15) . No overall trend of target strength with season and time of day 

could be detected over the entire study period . 

Spatially, target strength varied with platform side, depth and the interactions of depth 

and time of day and depth and season . Target strengths were significantly different on all sides 

of the platform (Table 16) . Significantly larger target strengths were found on the south side 

of the platform and smallest on the west (Table 16) . With respect to depth, target strengths 

were larger near the surface and above the substrate than at mid depth and immediately 

adjacent to the bottom (Table 17) . While the interactions of depth and time of day and season 

and depth were significant (Table 12), no consistent trends were observed in these interactions . 

Environmental variables that significantly affected target strength included temperature, 

north, east current vector north squared and east squared current vectors (Table 13) . The 

relationship between temperature and target strength showed a slight increase in target 

strengths as temperature increased. Target strength also increased with north and east current 

vector and north and east squared vectors suggesting that at high current speeds, larger fishes 

were more common. 

19 
Grand Isle 94 

Target Strength Distribution 

Target strengths of fishes at the GI94 production platform were variable over the study 

period and a RBD ANOVA with platform side as a block was used to examine differences in 

target strength due to year, season, time of day, current vectors, temperature, dissolved 

oxygen, depth and selected interactions . Target strength varied significantly with year, season, 

time of day, depth, platform side, north current vector, east squared current vector, north 

current vector squared, north*east interaction, dissolved oxygen, temperature, season*time of 

day, time of day*depth, and season*depth (Table 18). 

Temporal differences in target strength were detected between year, season, time of 

day, the interactions of season*time of day, time of day*depth, and season*depth (Table 18) . 

Target strength was significantly different between 3 of the 4 years examined with significantly 

larger target strengths found in 1995 than all other years (Table 19). Target strengths from 

1994 and 1996 were not significantly different from one another and the smallest target 

strengths were found in 1997 (Table 19) . Target strengths were also were significantly 

different with season (Table 21) . Largest target strengths were found in the winter, followed 

by the spring and summer and smallest target strengths were found in fall (Table 20). While 

target strengths were significantly different with time of day, the contrasts were much smaller 

than any other temporal variable examined (Table 21) . Largest target strengths were found at 

midnight and dusk; dusk and noon samples were not significantly different from each other and 

noon and dawn samples were not significantly different (Table 21). 

Spatially, fish density varied with platform side and depth (Table 18). Target strength 

varied significantly on each side of the platform (Table 22) . Largest target strengths were 

found on the south side, followed by the west and north with smallest target strengths on the 

east side (Table 22). Target strength varied significantly with depth and the largest target 

strengths were found from 40 to 60 m and from 0 to 5 m (Table 23) . Intermediate target 

strengths were detected in the middle of the water column from 5 to 35 m, while smallest 

target strengths were found from 15 to 25 m (Table 23). 

Environmental conditions also impacted target strengths based on results from the RBD 

ANOVA (Table 18) . Target strengths were significantly affected by temperature, dissolved 

oxygen, north current vector, north squared and east squared current vector (Table 18). 

Target strengths decreased slightly with temperature indicating larger fishes were found during 

fall and winter . Increases in dissolved oxygen, slightly increased target strengths . Target 

strengths increased with the north current vector but decreased with north and east squared 

current vectors. These results show an increase in fish size with current speed, however at 

excessive current speeds (e.g ., Appendix 2-25) when currents over 40 cm/s were common, it 

is likely that fish size increased along with density . 

20 
Green Canyon 18 

Target Strength Distribution 

Target strength of fishes at the GC18 production platform varied over the study period 

and a RBD ANOVA with platform side as a block was used to examine for differences in 

target strength due to year, season, time of day, current vectors, temperature, dissolved 

oxygen, depth and selected interactions . Target strength was significantly different with 

platform side, time of day, depth, north current vector, north current vector squared and the 

interaction of time of day and depth (Table 24) . 

Temporal differences in target strength at GC 18 were found with time of day and the 

interaction of time of day and depth (Table 24). Largest target strengths occurred at dawn, 

target strengths at dusk and noon were not significantly different and smallest target strengths 

were found at midnight (Table 25). While the differences in target strengths were significant 

with respect to time of day the difference in dB was 1 .5 dB or approximately 3 .5 cm based on 

estimated fish lengths (Love 1971). With interaction of time of day and depth no consistent 

trends were found with the exception that the largest target strengths were found near the 

surface at all times. 

Spatially, target strength varied with platform side and depth (Table 24) . Significantly 

larger target strengths were found on the south side of the platform, with the west side second 

and the east and north sides smallest and not significantly different from each other (Table 26) . 

The target strength differences between largest and smallest platform side at GC 18 was the 

greatest observed at any of the sites and was 4 dB or approximately 12 cm based on estimated 

fish lengths (Love 1971). Target strengths were significantly different at all depths examined, 

and the largest target strengths were found near the surface (Table 27). No target strength 

data were found below 95 m, in agreement with the low or zero estimated densities from the 

same region. 

Target strengths increased with the north current vector and north squared current 

vectors. These results show an increase in fish size with current speed, however at excessive 

current speeds however currents speeds rarely exceeded 40 cm/s and it is unlikely that currents 

of this scale would cause alter the size distribution of fishes . 

21 

DISCUSSION 

This study again demonstrates the utility of merging hydroacoustics and visual survey 

techniques to study the fish assemblages at petroleum platforms . The combination of these 

techniques allows for the measurement of the area of influence of these defacto artificial reefs, 

estimates of abundance, size distribution and species composition throughout the water column 

and for extended time periods . 

Our results demonstrate the variability in the abundance, size distribution and species 

composition of fishes associated with petroleum platforms. Our results were similar to earlier 

studies as variability in the abundance of fishes is typical at both natural and artificial reefs 

(Gallaway 1980, De Martini et al . 1989, Gallaway et al. 1981, Putt 1982, Sale 1984, Chang 

1985, Shinn and Wicklund 1989, Bohnsak et al . 1991, Doherty 1991, Sale 1991, Bull and 

Kendall 1994, Stanley and Wilson 1996, 1997) . The variability in density and the size 

distribution of fishes at petroleum platforms in this project was linked to temporal, spatial and 

environmental variables. 

Spatial variability was consistently observed at all study sites . Fish density and size 

distribution of fishes varied significantly with depth, platform side and distance from the 

platform at ST54, GI94 and GC 18 . These results was similar to results from our past research 

(Stanley and Wilson 1995, 1996, 1997), findings by Morgan (1996), Gerlotto (1989) and 

Valdermarsen (1979) . During mobile acoustic surveys of platforms sited as artificial reefs 

(Morgan 1996) and production platforms near Cameroon (Gerlotto et al . 1989) densities within 

50 m of the sites were 3 to 10 times higher than nearby open water. The results of this study 

showed the highest densities of fishes were also observed within 50 m of all study sites, 

however differences in the rate of decline with distance were found between sites of different 

water depths . At the shallowest site, ST54, the decline in fish density with distance was 

precipitous; at distances greater than 18 m, fish densities were similar to that of the open 

waters of the northern Gulf of Mexico. Results from this study at ST54 are similar to those of 

our earlier work at a site of similar water depth but geographically separated by over 300 km 

(Stanley and Wilson 1995, 1996, 1997). At the deeper sites a drop in fish density with 

distance from the site existed, however fish density was higher to greater distances from the 

platform . A decline in fish density with distance did exist at both GI94 and GC 18 as after a 

distance of approximately 50 m density approached those found in the open waters of the Gulf 

of Mexico . 

The differences in the relationship of fish density with distance from site to site is likely 

due to the change in species composition and water clarity between shallow and deeper sites. 

At deepwater sites the water clarity was much greater thus allowing visually oriented species 

the capacity to range farther away from the site, while maintaining visual contact . Also, 

carangids were one of the dominant groups of fishes observed at the deeper sites and while 

these fishes associate with reefs they are pelagic animals and thus much more likely to range 

farther away from a site . Despite these complications, hydroacoustics again illustrated its 

effectiveness in defining "area of influence" of the platform defined as the effective size of the 

artificial reef to the fish assemblage. As we defined it, the area of influence extended 10 m at 

23 
GC18 and 18 m at GI94 and ST54 as fish densities within these distances were significantly 

higher than densities at greater distances. While these figures may lead to a conservative 

estimates of total abundance we feel it more accurately reflects the true abundance of fishes at 

the sites. 

The spatial variation observed with target strength and platform side revealed that target 

strengths were greatest on the south side of each of the study sites otherwise no uniformity was 

detected with target strength and platform side. Largest target strengths on the south side was 

also consistent with our past research (Stanley and Wilson 1997), however we are at a loss to 

explain the rationale for larger fishes on one side of the platform . In an attempt to decipher the 

variation in fish density and target strength with platform side current speed and direction data 

were modeled with these variables. While significant relationships were detected between 

density, target strength and current vectors they did little to clarify the relationships . With 

respect to target strength there was a positive relationship at all sites with the north current 

vector . This suggests that as current speed from the north increased than target strength would 

increase . However, based on our findings of the south side of the platform having significantly 

larger targets one would expect a negative relationship between target strength and north 

current vectors, indicating larger targets were found with southerly oriented currents . A more 

likely explanation of the larger target strengths on the south side of the platform may be due to 

platform design and their influence on fish behavior. Since the most complex construction of 

structures is found at the north end, the well bay area, this may be a refuge for smaller fishes 

and explain the smaller target strengths found on these sides. Past research has demonstrated a 

relationship between hole size and/or reef complexity with fish size (Shulman 1984, Hixon and 

Beets 1989) and since the construction of platforms on the south end is open with little shelter, 

larger fishes appear to be more common. 

The last spatial variable examined, and one of the primary questions to be addressed by 

the research, was the effect of depth on the density and size distribution of fishes . Similar 

results with respect to density and water depth were found for the two sites on the continental 

shelf, ST54 and GI94. Highest densities were found adjacent to the surface and the bottom . 

These results were similar to those of our earlier research (Stanley and Wilson 1995, 1996, 

1997) and those of Chang (1985), Shinn and Wicklund (1989) and Rooker et al . (1997) . The 

most dramatic result of the project was the change in density with depth at the site on the 

continental slope, GC 18 . A significant and striking decrease in fish density with depth was 

found, below 100 m where only very low fish densities fish were detected . Previous research 

supports these findings as species richness in the Pacific was negatively correlated with depth, 

especially in tropical latitudes (Stevens 1996) and bottom trawl data from the shelf break in the 

Gulf of Mexico (water depth > 110 m) documented the presence of 69 species however, low 

abundances were found and few reef dependent species were captured (Chittenden and Moore 

1977) . The concentration of fishes at GC18 near the surface is reflected in the fact that 88% of 

the fishes were found in the upper 60m ,of the water column. While near surface fish densities 

at GC18 were significantly higher than those below 60 m the near surface densities were only 

one half to two thirds of values found at sites on the continental shelf. The decrease is likely 

due to the location of GC 18 and its distance from the highly productive waters of the 

Mississippi River. Both ST54 and GI94 are regularly influenced by the highly productive 

24 
waters from the Mississippi River as reflected in the lower surface salinities observed at these 

sites. The high salinities observed at GC 18 varied little from surface to the bottom, indicative 

of low productivity oceanic waters and the oligotrophic conditions appear to be reflected in 

lower fish densities even near the surface. 

Water depth also influenced the size distribution of fishes represented by low mean 

target strengths at the shallowest site (ST54) and largest at the deepest site (GC 18). Target 

strength also varied with depth at each site . Significantly larger target strengths were found 

near the surface and than generally decreased significantly with depth at each site . These 

results are different than our earlier research where target strength was shown not to be 

significantly different with depth (Stanley and Wilson 1996, 1997) . The variation in size 

distribution with depth is likely due to the change in species composition with depth detected at 

each site . 

The environmental variables examined measured influenced the density and target 

strength of fishes at the sites examined but not to the extent of the spatial and temporal factors. 

Environmental variables, including temperature, dissolved oxygen, current speed and 

direction, had their greatest impact on density and target strength at ST54 and least influence at 

GC 18 . The large impact at ST54 may be due to the large variation in environmental variables 

observed at the site . Temperatures varied by over 10 °C from summer to winter and while a 

positive relationship exited between temperature and density, the highest observed densities 

were found during cooler periods suggesting a bell shaped relationship where an optima is 

reached at a middle value with lower density values at the extremes . A similar relationship 

between temperature and density existed at GI94 . Where a significant relationship existed 

between temperature and target strength (ST54 and GI94) divergent results were found . At 

ST54 a positive relationship existed between temperature and target strength . This relationship 

may be due to the presence of larger migratory species during the summer including cobia and 

tarpon . At GI94 a negative relationship existed between target strength and temperature and 

this is likely due to the large influx of blue runner, a small carangid, during winter . 

Dissolved oxygen had a significant effect on density at ST54 and GI94 and target 

strength on GI94. Due to the location of ST54, it is typically impacted by the hypoxic events 

common during the warmer months off Louisiana coast (Rabalais et al . 1985) . During 

sampling trips in early June and late July of 1996, hypoxia was found at ST54 . During June 

1996 dissolved oxygen levels were less than 1 ppm from 20 - 22 m and in July the hypoxic 

zone was substantially larger as dissolved oxygen levels were less than 0.5 ppm from 15 to 22 

m. Not surprisingly fish densities were zero in these areas and an overall positive relationship 

existed between dissolved oxygen and density at ST54. This relationship was reinforced 

during the winter when high dissolved oxygen levels were present and densities were highest. 

An interesting observation during the hypoxic events at ST54 were the elevated fish densities 

found above the hypoxic layers . When overall fish abundance was compared between hypoxic 

and oxic summer sample periods, no significant difference in abundance was detected . This 

result suggests that a vertical compression of the fishes into the oxygenated water column 

occurred with little or no migration away from the site . Dissolved oxygen also significantly 

affected fish density and target strength at GI94 . While hypoxia was not observed at GI94 a 

25 
positive relationship was found between dissolved oxygen and density. This observation may 

be due to the highest densities observed in the winter when dissolved oxygen levels were 

highest. 

The relationships between current speed and direction with density and target strength 

was not consistent and varied with site . At ST54, a positive correlation was found with current 

speed and density while at GI94 and GC 18, negative relationships were observed . Past 

research has found that highest fish densities were up current of petroleum platforms 

(Continental Shelf Associates 1982, Putt 1982), while Chang (1985) and Lindquest and 

Pietrafesea (1989) observed that fishes oriented down current of artificial reefs. Our earlier 

research (Stanley and Wilson 1996, 199 did not identify a consistent relationship of fishes 

orienting up or down current of a petroleum platform and it would appear that results from this 

project support the conclusion that no consistent relationship existed between fish orientation 

and platform side. Since median current speeds ranged from 8 to 19 cm/s at all the sites, than 

observed current speeds were not strong enough to influence the behavior of nektonic fishes 

with respect up or down current aggregations (Baxter 1969) . 

The temporal variation of density and target strength of fishes demonstrated the lack of 

consistent response to these variables. The longest temporal scale variable examined was 

between years and was only found to be significant at GI94 for both density and target 

strength . Highest densities were found in 1997 (although only one sampling trip occurred in 

1997) and largest target strengths in 1995 at GI94. Seasonal differences in density and target 

strength were observed at all sites where highest fish densities were found during cooler 

periods, specifically fall and winter . This is similar to our earlier research (Stanley and Wilson 

1996, 1997) but contrary to other research at platforms and artificial reefs in the northern Gulf 

of Mexico (Gallaway 1980, Lukens 1981, Gallaway and Lewbel 1982, Putt 1982). These 

differences as outlined in Stanley and Wilson (1997) are presumably due to the differing 

sampling techniques between our research and others . Prior to our use of hydroacoustics to 

assess abundance of fishes at petroleum platforms, only visual surveys were performed . While 

visual surveys are effective in high visibility conditions, they can be biased and underestimate 

abundance in low visibility conditions (Bohnsak and Bannerot 1986, Charbonnel et al . 1996). 

Since visibilities are generally poor during cooler periods in the northern Gulf of Mexico, it is 

probable that the earlier visual surveys underestimated the abundance of fishes and did not 

accurately reflect the total number of fishes at the sites. 

The seasonal variation in target strengths observed at ST54 and GI94 were not 

consistent. Largest target strengths were found in the summer and smallest in the winter at 

ST54 while the reverse were detected at GI94 . The results from ST54 were similar to those of 

our earlier research and was presumably due to the influx of large seasonal migrants such as 

cobia and tarpon in the summer. Unlike our earlier research (Stanley and Wilson 1996, 1997) 

variation due to time of day was observed at ST54 and GI94 in this study . At ST54 highest 

densities were found at midnight indicating some attraction to the site may have occurred due 

to the presence of high intensity artificial lights at the site . At GI94 highest densities were 

found at dawn and lowest at noon and dusk. It is difficult to explain our results with classic 

crepuscular activity of fishes observed at natural and artificial reefs with highest densities 

26 
during the day and lowest a night . On natural and artificial reefs it is hypothesized that as light 

level decreases, the attraction to sites by fishes may decrease due to a loss of visual acuity, also 

off reef feeding at night is common by many fishes and this would cause a decrease in 

abundance of fishes at night (Munz and MacFarland 1973, Hobson 1974, McFarland et al, 

1979, Heffman et al. 1982, Collins and Pettigrew 1988, Thorne et al . 1989) . Target strengths 

were largest at ST54 during dawn and noon samples while at GI94 the target strengths were 

largest at midnight. The presence of high intensity artificial lights at these sites may influence 

the behavior of fishes at these sites and cause the changes from expected patterns common at 

natural and unlit artificial reefs. 

Despite the range of depths of the sample sites, many species were common to all the 

sites. While approximately 20 species were observed at a site over the study period, 6 species 

made up over 90% of the fishes observed on any survey . The dominant six species by site 

(highest to lowest abundance) were ; GC 18 creolefish, blue runner, Bermuda chub, almaco 

jack, greater amberjack, and barracuda; GI94 ; blue runner, horseeye jack, red snapper, 

mangrove snapper, gray triggerfish and barracuda; ST54 ; Atlantic spadefish, bluefish, blue 

runner, mangrove snapper, red snapper and sheepshead. The species observed during this 

project agreed with the past research in the northern Gulf of Mexico (Sonnier et al . 1976; 

Gallaway 1980; Continental Shelf Associates 1982 ; Gallaway and Lewbel 1982 ; Putt 1982 ; 

Stanley and Wilson 1990, Rooker et al . 199'x. Past research (Sonnier et al . 1976, Stanley and 

Wilson 1990, Rooker et al . 199 noted that over 35 species were associated with platforms in 

the northern Gulf of Mexico, while we detected a total of 36 species over the three study sites. 

Despite the disparate methods and temporal differences there is general agreement in the 

species composition between this and past research indicating that platform assemblages are 

fairly predictable. 

A unique observation from this study was the presence of yellowtail snapper at GC 18. 

It is a common species on natural reefs in the Caribbean and southern Gulf of Mexico, but it is 

been rarely reported on natural reefs and platforms in the northern Gulf of Mexico (Darnell et 

al. 1983) . During research trips in fall 94, winter 95 and spring 95, yellowtail snapper were 

relatively common at GC18 but were not observed on any subsequent surveys. This suggests 

these fishes either migrated away or experienced significant natural mortality and became 

extinct at the site and did not recolonize . 

The species observed at ST54 were very similar to those found at platforms of similar 

depth by Putt (1982) and Stanley and Wilson (1996, 1997). An exception to this was the 

observation of tarpon at ST54, a species not previously reported during any visual observation 

research at platforms but are targeted by anglers and caught near petroleum platforms (Stanley 

and Wilson 1990, 1991). 

Seasonal migrations were common at each of the study sites. Since this research took 

place throughout the year, we were able to document the seasonality alluded to by past 

research but not well documented (Sonnier et al . 1976, Putt 1982, Rooker et al . 199'x . 

Common seasonal migrations observed in the winter included an increase in the abundance of 

Florida pompano and bluefish at ST54 ; blue runner and barracuda at G194 and GC18 . 

27 
Increased abundances during the summer season included the tarpon and cobia at ST54, cobia, 

red snapper, greater amberjack and almaco jack at GI94, while no summer migrants were 

observed at GC18. 

Since only 6 species made up over 90% individuals each site on any survey, platform 

assemblages could be characterized as not specious but as dominated by a few species. While 

the species found at each site were somewhat unique and the dominant species at each site was 

different, overlap of observed species existed between sites, especially adjacent sites. Previous 

researchers have noted a zonation of the assemblage of fishes associated with platforms and 

have divided the shelf waters of the northern Gulf of Mexico into three zones, coastal (water 

depth < 27 m), offshore (water depth 27 to 64 m) and bluewater (water depth > 64 m) 

(Gallaway 1980, Gallaway et al . 1981, Gallaway and Lewbel 1982) . While our results 

generally agree with the outlined zonation we feel that there is a large crossover between zones 

than previously described, especially seasonally. These conclusions were also echoed by 

Rooker et al . (1997), during a survey of the platform High Island A389 . While Rooker et al . 

(1997) generally agreed with the zonation as defined by Gallaway (1980) there are significant 

differences and considerable overlap with shallower sites indicating it is problematic to define 

species composition only by depth. Comparison of our research with species composition from 

the High Island A389 site (water depth 125 m) surveyed by Rooker et al . (199' found the 

overall species composition was most similar to GC 18 (water depth 219 m) including the 

dominance of creolefish . Rooker et al . (199 documented the presence of a large number of 

midwater carangids, but due to their study design and emphasis on cryptic reef fishes, they 

were not directly enumerated . 

Based on our research and examination of the results from past platform studies, there 

generally is a keystone species that dominates the composition of fishes at a site, e.g., Atlantic 

spadefish at ST54, blue runner at GI4 and creolefish at GC18, but after the dominant species 

overlap of species existed between sites. Additionally, large fluctuations in abundance of 

species were common at all the sites over the study period . Due to the apparent migration of 

many of the fishes common at platforms in the northern Gulf of Mexico, and because of the 

range of depths and geographical location of these sites it is difficult to assign species to a 

certain zone . It may be more accurate to assign most species to a platform assemblage 

grouping with a secondary category on depth . 

The trophic structure of the fishes at all three study sites was similar to results at 

natural reefs due to the dominance of planktivorous omnivores (Shaffer and Rosen 1961, Smith 

and Tyler 1972, Hobson 1974, 1992) . However, while the trophic structure was similar 

between natural reefs and platforms the species composition of planktivores at natural reefs is 

different than those found at platforms . At natural reefs planktivorous Serranids, 

Chaetodontids, Pomacentrids, Holocentrids, Priacanthids and Balistids typically dominate the 

taxa (Randall 1967, Hobson 1974, 1991) . While at platforms only a planktivorous senanid, 

creolefish, was found only at GC18. At the other sites planktivores dominate but the species 

were Atlantic spadefish at ST54, an Ephippid, and GI94 the dominant planktivore was blue 

runner, a Carangid . While the species composition at platforms in the northern Gulf of 

Mexico is generally different than from natural reefs, the trophic structure is similar as 

28 
planktivores made 55 to 87% of the fishes observed at a site and this is similar to the results 

from natural reefs as planktivores can make up to 98% of the fishes found at natural reef 

(Hobson 1974, 1991, Sale et al . 1991) . Another similarity between the trophic structure 

natural reefs and petroleum platforms is the relatively small proportion of piscivores. At 

natural reefs piscivores makeup 10 to 20% of the fishes at a site, this compares favorably with 

our results as piscivorous Senanids, Lutjanids and Carangids made up 10 to 24% of the fishes 

observed . At the trophic scale it would appear that the assemblage of fishes at petroleum 

platform function similarly to observations of the community of fishes at natural reefs with 

respect to the dominance of planktivores and the relative low numbers of piscivores . 

Comparison of our results with other petroleum platform studies from the northern Gulf 

of Mexico revealed similarities and significant differences in density and abundance. 

Comparison of acoustically derived estimates of density from our past research showed similar 

density values with those from this project especially at ST54 and GI94 . Mean densities from 

our earlier work (Stanley and Wilson 1995, 1996, 1997) at a site in 24 m of water were 0.244 

(+/- 0.062, 95% confidence interval) fish- M-3, while mean densities found during this project 

were 0.333 (+/- 0.034) fish-m-' at ST54, 0.496 (+/- 0 .017) fish-m-' at GI94 and 0 .029 (+/-

0 .003) fish-m-' at GC18 . With the exception of GC 18, these values are consistent with those 

from Putt (1982) for a platform in 22 m of water off the Texas coast and an order of magnitude 

higher than the results of Continental Shelf Associates (1982) from four platforms surveyed in 

June 1980 . Both Putt (1982) and Continental Shelf Associates (1982) used only visual surveys, 

Putt employed stationary cameras and Continental Shelf Associates used a ROV for visual 

surveys. While the densities from previous studies are comparable to those estimated from our 

earlier and current research using hydroacoustics ; the visual techniques utilized are of limited 

value in low visibility by the authors' admission and their conclusions are limited to 

characterizations of fish populations under high visibility conditions . The densities found at 

platforms also are much higher than those from the open waters of the Gulf of Mexico. 

Morgan (1996) acoustically measured fish densities at artificial reefs in water depths from 20 

to 35 m on the continental shelf off the Louisiana coast and found mean fish densities were 

approximately 0.01 fish- m-3 . Based on all the results to date it is apparent that large 

concentrations of fishes are found around these structures in the northern Gulf of Mexico but 

the debate continues as to the exact function of these structures on whether they increase 

productivity or attract existing organisms . 

Total fish abundance estimates from the platforms in this project fall within the range of 

estimates at platforms from our earlier research in the Gulf of Mexico but are higher than those 

derived by visual only surveys. Stanley and Wilson (1995, 1996, 1997) calculated that there 

were on average a total of 12,473 (+/- 6,522, 95 % confidence interval) fishes at a site in 24m 

of water, while during this project estimates of the total number of fish per site were 13,472 

(+/- 1,346) at ST54, 28,952 (+/- 1,806) at GI94 and 13,856 (+/- 1,324) at GC18 . Visual 

survey estimates were consistently lower than those derived using combined hydroacoustics 

and visual surveys. Putt (1982) estimated that a platform in 22 m of water had an average of 

1,924 fish from July through September while single point count estimates by Continental Shelf 

Associates (1982) at four platforms off the Louisiana coast, found 283 to 3,955 fish associated 

with individual platforms, in water depths from 28 to 31 m. Rooker et al . (199' performed 

29 
visual surveys in the upper 24 m of a platform in 125 m of water and estimated 3,586 fishes 

were found at the site, however this included many cryptic and reef associated fishes that we 

did not include in our results nor did they include the large number of carangids and scombrids 

observed. The study by Rooker et al . (199' would appear to be the best visual estimate of 

fishes directly associated with a platform as water clarity was not an issue and their 

methodology was more thorough and superior to earlier visual surveys . However, it is 

apparent that due to the open construction of platforms, that visual surveys alone underestimate 

or cannot assess the large number schooling species at these sites. Other differences may be 

due to the larger near-field area of influence measured in this study. Earlier researchers did 

not directly measure the near-field area of influence and assumed it to be 5 m (Continental 

Shelf Associates 1982, Putt 1982) . The near-field area of influence measured at ST54 and 

GI94 was 18 m while at GC 18 it was defined as 10 m. The relationship between density and 

distance was well defined statistically at ST54 and GI94. Densities within 18 m of the site 

were significantly higher than all other distances measured. At GC 18 the relationship was not 

as well defined but based on acoustic derived density data and visual observations, the fishes 

remained close to the structure and 10 m was chosen as the near-field area of influence. 

Another possible explanation for the higher total fish abundance estimates from our research 

than those of Putt (1982) and Continental Shelf Associates (1982) may be size of the platform. 

Previous research (Rounsefell 1972, Ogawa et al 1973, Grove and Sonu 1983 ; Rountree 1989; 

Stanley and Wilson 1990) indicated that fish abundance increased with increasing artificial reef 

size and since ST54 and GI94 were larger than three of the four platforms compared in other 

studies this may explain some of the variation. Another likely explanation of the higher 

abundances detected during our research is the utilization of dual-beam hydroacoustics which 

did not influence fish behavior, was not limited by visibility and could determine the area of 

influence of the reef. The combination of these factors allows for more accurate assessments of 

the abundance of fishes at these sites . 

One of the most interesting results of the project was the comparison of abundance 

between the sites. GC 18 was 3 to 10 times larger than the others but the total abundance 

estimates were not significantly different than the smallest site (ST54), while the abundance 

estimates from GI94 was twice that of the other sites. Since structure size has been shown to 

affect fish density and the observation of higher density and abundance at the mid-size 

platform, it would appear that an optimal reef size may exist and this is consistent with results 

from our earlier research (Stanley and Wilson 1991) . Previous studies have shown fish 

abundance is directly correlated with reef size to a maximum reef volume of 4,000 m3 (Ogawa 

et al . 1973) or 25,000 - 50,000 ft2 (Rounsefell 1972) . While the platform with the highest 

abundance GI94, is larger than the optima from a reef volume perspective, due to the open 

construction of platforms, it is comparable to the optimal surface areas estimate from 

Rounsefell (1972) . The low abundances observed at GC18 is likely due to its location and the 

water depth at the site . Since fish abundance was essentially zero below 100 m and densities 

above 100 m were lower than the other sites, these two factors combined to produce the low 

abundances observed at the site . Due to the location of GC 18 it is not influenced by the 

eutrophic waters on the continental shelf and the outflow from the Mississippi river, it most 

influenced by oligotrophic oceanic waters from the Caribbean. The combination of water 

depth and oligotrophic conditions likely reduce the abundance of fishes at the GC18 . 

30 
Conclusions 

The 4,000 petroleum platforms in the northern Gulf of Mexico, provide an estimated 

12 .1 km2 of additional hard substrate (Stanley and Wilson 1997) to a ecosystem that is 

dominated by a mud/sand substrate (Parker et al . 1983). The total area of the MMS No 

Activity Zones (this includes known natural reefs and hard bottom areas in the northern Gulf of 

Mexico) is 292.81 km2 (Dr. Ann Bull, personal comm). The additional hard substrate 

provided by the petroleum platforms acting as defacto artificial reefs increases the amount of 

hard bottom habitat by 4 .1 % from Destin, Fl to Brownsville, TX . Off Louisiana the 

contribution is greater as the 3,600 platforms off the coast provide an estimated 10.9 km2. The 

total area of the seventeen MMS No Activity Zones off the Louisiana coast is 104.5 km2, based 

on these estimates platforms increase the hard bottom by 10.4%. The expansion of hard 

substrate habitat especially habitat in the upper water column has undoubtedly changed the 

dynamics of energy flow and influenced the utilization of marine resources but it has proved 

difficult to quantify the impact of these structures . Since 1990 over 90% of the commercial 

red snapper harvest has occurred off the Louisiana and Texas coasts (Schirriapa and Legault 

1997) and while statistics do not exist on the percentage of red snapper caught at petroleum 

platforms, it is assumed to be a significant portion . Additional support of the importance of 

petroleum structures to fisheries was found in the highest published angler catch rates at 

petroleum platforms (Stanley and Wilson 1990) . Fishes important to recreational and 

commercial fishes were common at the each of our study sites . At ST54 this included on 

average an estimated 1,000 red and 1,800 mangrove snapper as well as Florida pompano, 

cobia and gray triggerfish . Recreationally and commercially significant fishes common at 

GI94 included an estimated 870 red snapper, 290 greater amberjack, 290 gray triggerfish, 319 

mangrove snapper and 144 scamp on average. While at GC 18 commercially and recreational 

important carangids dominated, as an estimated 2,260 almaco jacks and 1,052 greater 

amberjack were found . Based on these results and the use of platforms by recreation and 

commercial groups it is obvious that these structures are an important component of the 

fisheries in the region . 

In recognition of the benefits of artificial reefs to marine fisheries in the northern Gulf 

of Mexico, Louisiana and Texas created artificial reef programs where retired petroleum 

platforms are the material of choice (Wilson et al . 1987, Stephan et al . 1990) . The standard 

deployment of these structures as reefs involves placing the jacket on its side. However, this 

deployment minimizes vertical relief and if a platform such as GC 18 was deployed in this 

manner it would extend approximately 80 m off the bottom. Based on our results a toppled 

deepwater artificial reef would be utilized by few fishes and a the structure sited in this manner 

would have limited value as an artificial reef. This project is the first demonstrating the 

importance of vertical relief in maximizing the effectiveness of platforms as artificial reefs 

especially with respect to deep water environments . 

There are few assessments of the abundance of fishes at platforms in other areas of the 

world, despite the fact that over 2,500 of these structures are found outside of the Gulf of 

Mexico (Aabel et al . 1997) . Estimates of fish abundance at structures in the North Sea based 

31 
on experimental netting and visual surveys with ROV's have revealed high abundances of 

platform associated fishes (Valdermarsen 1979, AUMS 1987, ICIT 1991, Cripps and Aabel 

1995, Cripps et al . 1995, Aabel et al . 199'x . Mean density and abundance values were 

comparable to those from the northern Gulf of Mexico as 0.3 fish-m-' were detected by Cripps 

and Abel 1995 and total abundance estimates in the region range from 9,000 to 80,000 fishes 

varying with water depth, platform size and location (Valdermarsen 1979, AUMS 1987, WIT 

1991, Cripps and Aabel 1995, Cripps et al . 1995, Aabel et al. 1997) . These results along with 

those from the Gulf of Mexico and the west coast of Africa (Gerlotto et al . 1989) clearly 

demonstrate that petroleum platforms are effective artificial reefs in a variety of climates and 

with various species assemblages . 

This research confirms the variability of fish assemblages associated with petroleum 

platforms and reinforces the need to sample on each side and throughout the water column to 

obtain an accurate estimate of fish abundance. It also demonstrates the importance of 

petroleum platforms to the marine environment of the northern GOM due to the high 

abundance of fishes found at the sites. Although some variance was observed, 10,000 to 

30,000 fishes were found at a site at any one time and since over 1,000 platforms are found in 

similar water depths it is clear that these structures impact the fisheries of the region . 

This study continues to demonstrate the utility of merging hydroacoustics and visual 

survey techniques to study the assemblage of fishes associated with petroleum platforms . The 

combination of these techniques allows for the measurement of the area of influence of these 

defacto artificial reefs, estimates of abundance, size distribution and species composition 

throughout the water column and over long time periods . 

32 
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38 
Table 1 . RBD ANOVA (block on platform side) results of vertical log fish density (log (fish density/m 3) 

with platform side, year, season, time of day, depth, current vectors, temperature, salinity, dissolved 

oxygen and selected interactions at the ST54 petroleum platform . 

Source DF SS MS F Prob > F 

Model 308 129 .00907430 0.41886063 14 .09 0.0001 

Error 1596 47.44809218 0.02972938 

Corrected Total 1904 176 .45716648 

R-Square C.V. Root MSE LDENSITY 

Mean 

0.731107 87.90991 0.1724221 0 .1961350 

Variables DF Type III SS Mean Square F Value Pr > F 

Side 3 14 .78826719 4.92942240 165 .81 0.0001 

Year 1 0.01226440 0.01226440 0.41 0.5208 

Season 3 2.36471052 0.78823684 26.51 0.0001 

Diet 3 1 .48166178 0.49388726 16.61 0.0001 

Depth 4 1 .64875440 0.41218860 13.86 0.0001 

Temperature 1 0.50166204 0.50166204 16.87 0.0001 

Dissolved 

oxygen 

1 0.56616923 0 .56616923 19.04 0 .0001 

Salinity 1 0.02415845 0.02415845 0.81 0.3675 

North vector 1 0 .17789554 0 .17789554 5 .98 0 .0145 

East vector 1 1 .28431015 1 .28431015 43 .20 0 .0001 

North squared 

vector 

1 0 .19835984 0.19835984 6.67 0 .0099 

East squared 

vector 

1 0.08600079 0.08600079 2.89 0.0892 

North * East 1 0.00384716 0.00384716 0 .13 0.7191 

Season * Diel 9 3 .89885440 0.43320604 14.57 0.0001 

Diel *Depth 12 4.65341619 0.38778468 13.04 0.0001 

Season * Depth 

l 

I 12 I 8.31623532 I 0.69301961 I 23.31 I 0.0001 

39 
Table 2. RBD ANOVA (block on platform side) results of horizontal log relative 

fish density (log (fish density/m 3) with platform side, year, season, time of day, 

distance from the platform and selected interactions at the ST54 petroleum platform . 

Source DF SS MS F Prob > F 

Model 591 67.26231465 0.11381102 32.41 0.0001 

Error 4828 16.95542871 0.00351189 

Corrected Total 5419 84.21774337 

R-Square C.V . Root MSE LDENSII'Y 

Mean 

0 .798672 104.4581 0.0592612 0 .0567321 

Variables DF Type III SS Mean Square F Value Pr > F 

Side 3 1 .93480553 0.64493518 183 .64 0.0001 

Year 2 0.55152158 0.27576079 78.52 0.0001 

Season 3 16.74014333 5.58004778 1588 .90 0.0001 

Diel 3 3 .26312963 1 .08770988 309.72 0.0001 

Distance 3 2.04846570 0 .22760730 64.81 0.0001 

Season * Diel 9 7 .20927947 0 .80103105 228.09 0 .0001 

Diel * Distance 27 0 .93008887 0 .03444774 9.81 0 .0001 

Season * 

Distance 

27 3 .16415321 0.11719086 33 .37 0.0001 

Side * Season * 

Diel * Distance 

508 34 .03828042 0.06700449 19.08 0.0001 

40 
Table 3a. Number enumerated and percent species composition (in parentheses) 

by depth strata at South Timbalier 54 from July 30 - August 1, 1995 

from visual point count surveys . 

Depth (m) 

Species 0-5 5-10 10-15 15-20 20-22 0-20 

Atlantic Spadefish 178(39 .7) 198 (48.4) 246 (52.5) 120 (28.3) 75 (13.4) 817 (35.4) 

Barracuda 2(0.4) 1 (0.2) 1(0.2) 4(0.2) 

Bermuda Chub 

Bluefish 3(0.6) 1 (0 .2) 4(0.2) 

Bluerunner 145 (32.4) 59 (14.4) 191 (40.'n 226 (53.3) 364 (65.0) 985 (42.6) 

Cobia 1 (0 .2) 1 (0 .2) 1(0.2) 3(0.1) 

Florida Pompano 

Gray Triggerfuh 7(1 .7) 6(1 .1) 13(0.6) 

Jack Crevalle 4(1 .0) 1 (0 .2) 5(0.2) 

Lookdown 10(2.4) 8(1 .7) 18(0.8) 

Mangrove Snapper 2(0.4) 3(0.7) 8(1.7) 3(0.7) 10(1.8) 26(l .1) 

Red Snapper 26(6.1) 63 (11 .3) 89(3.9) 

Red Drum 

Rockhind 2(0.5) 2(0.1) 

Sheepshead 122 (27.2) 133 (32.5) 11 (2 .3) 37(8.7) 40(7.1) 343 (14.8) 

Tarpon 1 (0 .2) 1 (0 .0) 

*Note: If cell is empty, no individuals were observed of that species for that depth interval . 

41 
Table 3b . Number enumerated and percent species composition (in parentheses) by depth strata 

at South Timbalier 54 from October 24 - 25, 1995 from visual point count surveys . 

moth lml 

Species 0-5 5-10 10-15 15-20 20-22 0-22 

Atlantic Spadefish 232 (57 .9) 244 (41 .1) 122 (32 .1) 38 (24.7) 636 (34 .7) 

Barracuda 

Bluefish 

Bluerunner 87 (21 .7) 146 (24 .6) 97 (25 .5) 35(22.7) 365 (19 .9) 

Cobia 3 (0.8) 2(0 .7) 5(0.3) 

Florida Pompano 

Gray Triggerfish 1 (0.2) 1 (0.3) 2(0.1) 

Jack Crevalle 1 (0.2) 4(0.7) 1 (0.3) 2(0.7) 8(0.4) 

Lookdown 8(2.1) 8(0.4) 

Mangrove Snapper 16(4.0) 114 (19 .2) 101 (26 .6) 19 (12.3) 250 (13 .6) 

Red Snapper 1 (0.2) 1 (0.3) 33 (21 .4) 249 (81 .9) 284 (15 .5) 

Red Drum 1 (0 .3) 1 (0 .1) 

Rockhind 2(1 .3) 2(0.1) 

Sheepshead 65 (16.2) 84 (14 .1) 47 (12 .4) 26 (16 .9) 49 (16 .1) 271 (14.8) 

Tarpon 1 (0 .6) 1(0.1) 

42 
Table 3c. Number enumerated and percent species composition (in parentheses) by depth strata at 

South Timbalier 54 from January 30 - February 1, 1996 from visual point count surveys. 

Deqth (m) 

Species 0-5 5-10 10-15 15-20 20-22 0-22 

Atlantic Spadefish 211 (84 .7) 116 (35 .6) 95 (43 .0) 151 (36.5) 118 (31 .0) 691 (43 .4) 

Barracuda 4(0 .0) 

Bermuda Chub 1 (0 .0) 

Bluefish 57 (17 .5) 28 (12 .7) 125 (302) 210 (13 .2) 

Bluerunner l (O .4) 7(2.1) 3 (1 .4) 4 (1 .0) 3 (0 .8) 18(l .1) 

Cobia 14 (0 .2) 

Florida Pompano 14 (63) 10 (2 .4) 1 (0 .3) 25(l .6) 

Gray Triggerfish 1 (0 .5) 1 (0 .3) 2(0.1) 

Jack Crevalle 4(l .2) 6(2.7) 7(l .7) 1 (0 .3) 18(l .1) 

Lookdown 2(0.5) 2(0.1) 

Mangrove Snapper 1 (0 .4) 5 (1 .5) 6(2.7) 5 (1 .2) 1 (0 .3) 18(1 .1) 

Red Snapper 28 (12.7) 66 (15 .9) 139 (36.5) 233 (14.6) 

Red Drum 

Rockhind 

Sheepshead 36 (14 .5) 137 (42 .0) 40 (18 .1) 46(11 .1) 115 (30.2) 374 (23 .5) 

Tarpon 11 (0 .1) 

43 
Table 3d. Number enumerated and percent species composition (in parentheses) by depth strata at 

South Timbalier 54 from June 6 - 7, 1996 from visual point count surveys . 

Death (m) 

Species 0-5 5-10 10-15 15-20 20-22 0-22 

Atlantic Spadefish 181 (55 .0) 40 (14 .3) 15(6.9) 7(13 .0) 243 (27 .6) 

Barracuda 

Bermuda Chub 

Bluefish 3(0.9) 2(0.9) 5(0.6) 

Bluerunner 48 (14.6) 10(3.6) 58(6.6) 

Cobia 1 (0 .5) l (O .1) 

Florida Pompano 

Gray Triggerfish 1 (0 .4) 5(2.3) 1 (1 .9) 7(0.8) 

Jack Crevalle 3 (1 .1) 3 (0 .3) 

Lookdown 16(4.9) 20(7.2) 36(4.1) 

Mangrove Snapper 67 (20 .4) 172 (61 .6) 101 (46 .5) 11 (20.4) 351 (39 .9) 

Red Snapper 1 (0 .4) 6(2.8) 6(11 .1) 13 (1 .5) 

Red Drum 

Rockhind 

Sheepshead 14(4 .3) 32 (11 .5) 87 (40 .1) 29 (53 .7) 162 (18 .4) 

Tarpon 

44 
Table 3e. Number enumerated and percent species composition (in parentheses) by depth strata 

at South Timbalier 54 from July 17 - 18, 1996 from visual point count surveys. 

Death (m) 

Species 0-5 5-10 10-15 15-20 20-22 0-22 

Atlantic Spadefish 28 (48 .3) 95 (18 .6) 123 (21 .5) 

Barracuda 

Bermuda Chub 1 (0 .2) l (O .2) 

Bluefish 

Bluerunner 

Cobia 2(0.4) 2(0.3) 

Florida Pompano 

Gray Triggerfish 2(0 .4) 2(0.3) 

Jack Crevalle 

Lookdown 

Mangrove Snapper 15 (25 .9) 266 (52 .1) 281 (49 .1) 

Red Snapper 15(2.9) 3(100.0) 18 (3 .1) 

Red Drum 

Rockhind 

Sheepshead 15 (25 .9) 130 (25 .4) 145 (25 .3) 

Tarpon 

45 
Table 3f. Number enumerated and percent species composition (in parentheses) by depth strata 

at South Timbalier 54 from March 28 - 29, 1997 from visual point count surveys . 

Depth (m) 

Species 0-5 5-10 10-15 15-20 20-22 0-22 

Atlantic Spadefish 198 (71 .0) 177 (34 .4) 126 (31 .9) 20(7.3) 521 (27 .5) 

Barracuda 

Bermuda Chub 

Bluefish 

Bluerunner 42 (15 .1) 149 (29 .0) 119 (30 .1) 72 (263) 48 (11 .0) 430 (22 .7) 

Cobia 2(0.5) 1 (0 .2) 3 (0 .2) 

Florida Pompano 

Gray Triggerfish 

Jack Crevalle 1 (0 .4) 6(l .2) 1 (03) 6(2.2) 3 (0 .7) 17(0.9) 

Lookdown 7(l .8) 7(0.4) 

Mangrove Snapper 15(5 .4) 81 (15.8) 87 (22 .0) 66 (24 .1) 6(l .4) 255 (13 .4) 

Red Snapper 52 (19 .0) 287 (66.0) 339 (17.9) 

Red Drum 7(1 .6) 7(0.4) 

Rockhind 

Sheepshead 23 (8 .2) 96 (18 .7) 41 (10 .4) 37 (13 .5) 62 (14.3) 259 (13 .7) 

Tarpon 2(0.5) 6(2 .2) 1 (0 .2) 9(0.5) 

46 
Table 3g. Mean number enumerated and percent species composition (in parentheses) 

by depth strata at South Timbalier 54 for all research trips from July 1995 through March 1997 

from visual point count surveys . 

Depth (m) 

Species 0-5 5-10 10-15 15-20 20-22 0-22 

Atlantic Spadefish 1028 (58 .3) 870 (33 .2) 604 (36 .2) 336 (25 .8) 193 (11 .6) 3031 (33 .6) 

Barracuda 2(0.1) 1 (0.1) 1 (0.1) 4(0.0) 

Bermuda Chub 1 (0.0) 1(0.0) 

Bluefish 3(0.2) 57(2.2) 33 (2.0) 126 (9 .7) 219 (2.4) 

Bluerunner 323 (18 .3) 371 (14 .1) 410 (24 .6) 337 (25 .9) 415 (25 .0) 1856 (20 .6) 

Cobia 1 (0.1) 3 (0.1) 6(0.4) 4(0.2) 14(0.2) 

Florida Pompano 14(0.8) 10(0.8) 1(0.1) 25(0.3) 

Gray Triggerfish 4(0.2) 6(0.4) 8(0.6) 7(0.4) 25(0.3) 

Jack Crevalle 2(0.1) 17(0 .6) 8(0.5) 14(l .1) 4(0.2) 45(0.5) 

Lookdown 16(0.9) 30(l .1) 15(0.9) 2(0.1) 63 (0.'n 

Mangrove Snapper 116 (6.6) 641 (24 .4) 303 (18 .2) 104 (8 .0) 17(l .0) 1181 (13 .1) 

Red Snapper 17(0 .6) 38 (2.3) 183 (14 .0) 738 (44 .5) 976 (10 .8) 

Red Drum 8(0.5) 8(0.1) 

Rockhind 2(0.2) 2(0.0) 

Sheepshead 275 (15 .6) 612 (23 .3) 226 (13 .6) 175 (13 .4) 266 (16.1) 1554 (17.2) 

Tarpon 1 (0 .0) 2(0.1) 7(0.5) 1 (0 .1) 11(0.1) 

47 
Table 4a. Estimated number of fish by species (with 95 % confidence intervals) by depth strata 

at South Timbalier 54 from July 30 - August 1, 1995 from hydroacoustic and visual point count surveys . 

Depth (m) 

Species 0-5 5-10 10-15 15-20 20-22 0-22 

Atlantic 

S adefish 

983 .6 (66 .4) 788 .8 (71 .2) 529.7 (103 .4) 578.2 (136.2) 2880 .3 

(377 .2) 

Barracuda 4.0 (0.8) 4.2(l .0) 8.2(l .8) 

Bermuda 

Chub 

Bluefish 6.1 (1 .2) 4.1 (1 .0) 10.2 (2 .2) 

Bluerunner 802 .7 (54 .2) 234.7 (21 .2) 410.6 (80 .1) 1088.9 

256.6) 

2536.9 

412.1 

Cobia 5 .0 (0.3) 3.3 (0.3) 8.3 (0.6) 

Florida 

Pompano 

Gray 

Tri erfish 

34.7 (8.2) 34.7 (8 .2) 

Jack 

Crevalle 

16.3(l .5) 4.1 (1 .0) 20.4 (2 .5) 

Lookdown 39.1 (3 .5) 17 .2 (3.3) 56.3 (6.8) 

Mangrove 

Snapper 

9.9 (0.7) 11 .4(l .0) 17 .2 (3.3) 14.3 (3.4) 52 .8 (8.4) 

Red Snapper 124 .6 (29 .4) 124.6 (29.4) 

Red Drum 

Rockhind 10.2 (2.4) 10.2 (2.4) 

Sheepshead 673.9 (45 .5) 529.7 (47.8) 23 .2 (4.5) 177 .7 (41 .9) 1404.5 

(139 .7) 

Tarpon 3 .3 (0 .3) 3 .0 (0.3) 

TOTAL 2477 .5 

(167.3) 

1629.8 

(147.1) 

1008 .9 

(196.9) 

2043 .0 

(481 .4) 

7159 .2 

(992.7) 

*Note: If cell is empty, no individuals were observed of that species for that depth interval . 

48 
Table 4b . Estimated number of fish by species (with 95 % confidence intervals) by depth strata at 

South Timbalier 54 from October 24 - 25, 1995 from hydroacoustic and visual point count surveys. 

Depth (m) 

Species 0-5 5-10 10-15 15-20 20-22 0-22 

Atlantic 

S adefish 

6882.3 

1384.1) 

4325.4 

772 .2) 

1200.9 

316.4) 

896.4 (138.9) 13305.0 

(2611 .6 

Barracuda 

Bermuda 

Chub 

Bluefish 

Bluerunner 2579.4 

518 .7 

2589 .0 

462.2) 

954.0 (251 .4) 823.8 (127. 6946.2 

1360.0 

Cobia 29.9 (7.9) 15 .0 (2.3) 44 .9 (10.2) 

Florida 

Pompano 

Gray 

Tci erfish 

21 .0 (3 .8) 6.4(l .0) 27 .4 (4.8) 

Jack Crevalle 23 .8 (4.8) 73 .7 (13 .2) 11 .2 (3 .0) 15 .0 (2 .3) 123 .7 (23 .3) 

Lookdown 78.6 (20 .7) 78.6 (20 .7) 

Mangrove 

Snapper 

475 .5 (95 .6) 2020 .6 

(360.7) 

995 .1 (262 .2) 446 .4 (69 .2) 3937 .6 

(787.7 

Red Snapper 21 .0 (3 .8) 11 .2 (3 .0) 776.6 (120.4) 1751 .9 

(265.0 

2560.7 

392.2) 

Red Drum 6 .4(l .1) 6 .4(l .1) 

Rockhiad 47 .2 (7.3) 47 .2 (7.3) 

Sheepshead 1925.6 

(387.3) 

1483 .9 

(264.9) 

463 .9 (122.2) 613 .3 (95 .1) 344.4 (52 .1) 4831 .1 

(921 .6) 

Tarpon 21 .8 (3 .4) 21 .8 (3.4) 

TOTAL 

11886.6 

(2390.5) 

10524.2 

(1878.9) 

374.1 (985.8) 3629 .1 

(562.5) 

2139 .1 

323 .6) 

28553 .1 

6141 .3 

49 
Table 4c. Estimated number of fish by species (with 95% confidence intervals) by depth strata at 

South Timbalier 54 from January 30 - February 1, 1996 from hydroacoustic and visual 

point count surveys. 

Depth (m) 

Species 0-`5 5-10 10-15 15-20 20-22 0-22 

Atlantic 

S adefish 

1551 .7 

149.2 

343 .0 (39.4) 694 .2 (75 .7) 520 .3 (73 .1) 687 .3 (279.9) 3796 .5 

(617.3) 

Barracuda 

Bermuda 

Chub 

Bluefish 168.6 (19 .4) 205 .0 (22 .4) 430.5 (60.5) 804.1 (102.3) 

Bluerunner 7 .3 (0 .7) 20.2 (2.3) 22 .6 (2.5) 14 .3 (2.0) 17 .7 (7.2) 82 .1 (14.7) 

Cobia 

Florida 

Pompano 

101 .7 (11 .1) 34.2 (4.8) 6.7 (2 .7) 142 .6 (18.6) 

Gray 

Tri erfish 

8.1 (0 .9) 6.7 (2.7) 8.1 (1 .6) 22 .9 (5.2) 

Jack Crevalle 43 .6 (4.8) 24.2 (3 .4) 6.7 (2 .7) 74.5 (10.9) 

I .ookdown 11 .1 (4.5) 11 .1 (4 .5) 

Mangrove 

Snapper 

7.3 (0.7) 14.5(l .7) 43 .6 (4.8) 17 .1 (2.4) 6 .7 (2 .7) 89 .2 (12 .3) 

Red Snapper 205 .0 (22 .4) 226.7 (31 .8) 809.2 (329.6) 1240.9 

383.8) 

Red Drum 

Rockhind 

Sheepshead 265 .6 (25 .5) 404 .7 (25 .5) 292.2 (31 .9) 158.2 (22 .2) 669.5 (272 . 1790 .2 

(377 .5) 

Tarpon 

TOTAL 

1832.0 

(176.1) 

963.5 (110.8) 1614 .5 

(176.0) 

1425 .5 

(200.3) 

2217 .0 

(902.9) 

8052 .5 

(1566 .1) 

50 
Table 4d . Estimated number of fish by species (with 95% confidence intervals) by depth strata at 

South Timbalier 54 from June 6 - 7, 1996 from hydroacoustic and visual point count surveys . 

Denth lml 

Species 0-5 5-10 10-15 15-20 20-22 0-22 

Atlantic 

S adefish 

1388 .8 (89 .8) 231 .7 (21 .6) 69.7 (14.0) 273 .2 (64 .1) 1963 .4 

189.5) 

Barracuda 

Bermuda Chub 

Bluefish 22 .7(l .5) 9.1 (1 .8) 31 .8 (3 .3) 

Bluerunner 368 .7 (23 .9) 58 .3 (5.4) 427.0 (29 .3) 

Cobia 5 .1 (1 .0) 5 .1 (1 .0) 

Florida 

Pompano 

Gray 

Tri erfish 

6 .5 (0.6) 23 .2 (4.7) 39 .9 (9.4) 69.9 (14.7) 

Jack Crevalle 17.8 (1 .7) 17 .8(l .7) 

Lookdown 123 .7(8.0) 116 .6 (10 .9) 240.3 (18.9) 

Mangrove 

Snapper 

515.1 (33 .3) 998 .0 (93 .1) 469 .8 (94 .1) 428.7 (100. 2411 .6 

(321 .2 

Red Snapper 6.5 (0 .6) 28 .3 (5.7) 233 .3 (54.8) 268.1 (61 .1) 

Red Drum 

Rockhind 

Sheepshead 108 .6 (7.0) 186.3 (17.4) 405.2 (81 .2) 1128 .5 

(265.0) 

1828.6 

(370.6) 

Tarpon 

TOTAL 

2525.0 

I (163 .4) 

1620 .1 

I (151 .1) 

1010 .4 

I (202.4) 

2101 .4 

I (493.4) 

12.5 (3 .6) 

I 

7269.4 

I (1013.9) 

51 
Table 4e. Estimated number of fish by species (with 95% confidence intervals) by depth strata at 

South Timbalier 54 from July 17 - 18, 1996 from hydroacoustic and visual point count surveys . 

Depth (m) 

Species 0-5 5-10 10-15 15-20 20-22 0-22 

Atlantic 

S adefish 

1138 .7 

178.0 

837 .8 (80.9) 1976.5 

(258.9 

Barracuda 

Bermuda 

Chub 

9.0 (0 .9) 9.0 (0.9) 

Bluefish 

Bluerunner 

Cobia 18 .0 (1 .7) 18.0 (1 .7) 

Florida 

Pompano 

Gray 

Tri erfish 

18 .0 (1 .7) 18 .0 (1 .7) 

Jack Crevalle 

Lookdown 

Mangrove 

Snapper 

610 .6 (95 .4) 2346 .8 

226.7) 

2957 .4 

(322.1 

Red Snapper 130 .6 (12 .6) 1869.9 

(216.1) 

2000.5 

(228.7) 

Red Drum 

Rockhind 

Sheepshead 610 .6 (95 .4) 144.1 (110.5) 754 .7 (205 .9) 

Tarpon 

TOTAL 

2357.6 

(368.5) 

4504 .5 

(435 .1) 

1869 .9 

(216.1) 

825 .4 (293 .9) 10.8 (2.9) 9568 .2 

(1316.5) 

52 
Table 4f. Estimated number of fish by species (with 95% confidence intervals) by depth strata at 

South Timbalier 54 from March 28 - 29, 1997 from hydroacoustic and visual point count surveys . 

Depth (m) 

Species 0-5 5-10 10-15 15-20 20-22 0-22 

Atlantic 

S adefish 

3123.7 

(599.5) 

1921 .7 

(271 .9) 

681 .5 (112.2) 1928.4 

(221 .8) 

671 .9 (114.7) 8327.2 

(1320.1 

Barracuda 

Bermuda 

Chub 

Bluefish 944 .7 (133. 201 .3 (33 .1) 1595 .5 

(216.1) 

2741 .5 

(382.9 

Bluerunner 14.8 (2.8) 113 .4 (16 .0) 22.2 (3 .7) 52 .8 (7.2) 17.3 (3 .0) 220.5 (32 .7) 

Cobia 18A (2.9) 

Florida 

Pompano 

99 .8(16 .4) 126.8 (17.2) 6.5(l .1) 233 .1 (34.7) 

Gray 

Tri erfish 

7.9(l .3) 6.5(l .1) 14 .4 (2.4) 

Jack Crevalle 64 .8 (9.2) 42 .8 (7.0) 89 .8 (12 .2) 6.5(l .1) 203 .9 (29 .5) 

Lookdown 10.8(l .9) 10.8(l .9) 

Mangrove 

Snapper 

14.8 (2.8) 81 .0 (11 .5) 42.8 (7 .0) 63 .4 (8.6) 6 .5(l .1) 208 .5 (31 .0) 

Red Snapper 201 .3 (33 .1) 840.0 (113. 791 .1 (135.1) 1832.4 

(281 .9) 

Red Drum 

Rockhind 

Sheepshead 534 .8 (102 .6) 2267.2 

(320.8) 

286.9 (47.2) 586 .4 (79 .4) 654 .6 (111 . 4329 .9 

(661 .7) 

Tarpon 24.5 (4 .0) 

TOTAL 

3688.0 

(707.8) 

5398 .0 

(763 .9) 

1584 .9 

(261 .0) 

5283 .2 

(715.4) 

2167.5 

(370.0) 

18121 .6 

(2818.1) 

53 
Table 4g . Mean estimated number of fish by species (with 95 % confidence intervals) by depth strata 

at South Timbalier 54 from for all research trips from July 1995 through March 1997 from hydroacoustic 

and visual point count surveys . 

moth (m) 

Species 0-`5 5-10 10-15 15-20 20-22 0-22 

Atlantic 

S adefish 

2230.8 

(223 .6) 

1337.1 

114.0) 

636 .9 (63 .0) 665 .3 (54.3) 148 .5 (27.3) 5018 .6 

482.2 

Barracuda 1 .8 (0 .2) 2 .6 (0.2) 1 .3 (0.2) 5 .7 (0 .4) 

Bermuda 

Chub 

0.0 (0 .0) 1 .1 (0.1) 

Bluefish 7 .7 (0.8) 88 .6 (7.6) 35 .2 (3 .5) 250 .1 (20 .4) 381 . (32 .3) 

Bluerunner 700 .2 (70.2) 567.8 (48 .4) 432.8 (42 .8) 667 .9 (54.5) 320 .0 (58 .9) 2688 .7 

(274.8) 

Cobia 3 .8 (0 .4) 4 .0 (0.3) 7 .0 (0.7) 2 .6 (0 .5) 17.4 (1 .9) 

Florida 

Pompano 

14.1 (0.7) 20 .6(l .7) 1 .3 (0 .2) 36.0 (2.8) 

Gray 

Tri erfish 

8 .1 (0 .7) 7.0 (0 .7) 15 .5(l .3) 5 .1 (0.9) 35 .7 (3.6) 

Jack Crevalle 3 .8 (0.4) 24 .2 (2.1) 8.8 (0.9) 28.4 (2.3) 2.6 (0.5) 67 .8 (6.2) 

Lookdown 34.4 (3 .5) 44 .3 (3.8) 15 .8(l .6) 1 .3 (0.2) 95 .8 (9.1) 

Mangrove 

Snapper 

252 .5 (25 .3) 982.7 (83 .0) 320.2 (31 .7) 206 .3 (16.8) 12.8 (2 .4) 1774 .5 

(159.2 

Red Snapper 24.2 (2.1) 40.5 (4.0) 361 .0 (29.5) 569.6 (104.9) 995 .3 (140.5) 

Red Drum 6 .4(l .2) 6.4(l .2) 

Rockhind 5.2 (0.4) 5 .2 (0.4) 

Sheepshead 596.9 (59 .8) 938 .4 (80.0) 239.3 (23 .7) 345.5 (28 .2) 206.1 (37 .9) 2326 .2 

(229 .6) 

Tarpon 0.0 (0 .0) 1 .8 (0.2) 12.9(l .1) 1 .3 (0.2) 16.0 (1 .5) 

TOTAL 

3826.4 

(383.6) 

4027 .3 

(343 .4) 

1759 .5 

(174.0) 

2578 .7 

(210.4) 

1280 .0 

(235 .7) 

13471 .9 

(1346.'n 

54 
Table 5. RBD ANOVA (block on platform side) results of vertical log fish density (log(number of 

fish/m ) with platform side, year, season, time of day, depth, current vectors, temperature, salinity, 

dissolved oxygen and selected interactions at the GI94 petroleum platform . 

Source DF SS MS F Prob > F 

Model 719 658 .51165 0.91587 9.51 0 .0001 

Error 7210 694.42089 0.09631 

Corrected Total 7929 1352 .93255 

R-Square C.V. Root MSE LDENSITY 

Mean 

0.486729 94 .61222 0.3103 0.3280 

Variables DF Type III SS Mean Square F Value Pr > F 

Side 3 34.43292 11 .47764 119.17 0 .0001 

Year 3 1 .11 0 .37 12.17 0 .0001 

Season 3 88 .32148 29 .44049 305 .67 0.0001 

Diel 3 1 .45685 0.48562 5.04 0.0017 

Depth 11 20 .22683 1 .83880 19.09 0.0001 

Temperature 1 3.53954 3.53954 36.75 0.0001 

Dissolved 

oxygen 

1 4.91742 4 .91742 51 .06 0 .0001 

Salinity 1 0 .00003 0 .00003 0.00 0.9849 

North vector 1 1 .32898 1 .32898 13 .80 0.0002 

East vector 1 0.23100 0.23100 2 .40 0.1215 

North squared 

vector 

1 0.42743 0.42743 4 .44 0.0352 

East squared 

vector 

1 1 .98548 1 .98548 20.61 0.0001 

North * East 1 0.10200 0.10200 1 .06 0.3035 

Diel * Depth 33 4 .48975 0 .13605 1 .41 0.0590 

Side * Season * 

Diel *Depth 

658 I 226.51339 I 0.34425 I 3.57 I 0.0001 

55 
Table 6. RBD ANOVA (block on platform side) results of horizontal relative log fish density 

(log(number of fish/m 3) with platform side, year, season, time of day, distance from the platform 

and selected interactions at the GI94 petroleum platform. 

Source DF SS MS F Prob > F 

Model 612 186 .43939327 0.30463953 11 .84 0.0001 

Error 8327 214.25821327 0 .02573054 

Corrected Total 8939 400.69760654 

R-Square C.V. Root MSE LDENSITY 

Mean 

0.465287 175 .7350 0 .1604074 0 .0912780 

Variables DF Type III SS Mean Square F Value Pr > F 

Side 3 13 .25275329 4.41758443 171 .69 0.0001 

Year 3 17.72176044 5.90725348 229.58 0.0001 

Season 3 17.15944638 5.71981546 222.30 0.0001 

Diel 3 0 .28291537 0 .09430512 3 .67 0 .0118 

Distance 9 6 .20883438 0 .68987049 26 .81 0 .0001 

Season * Diel 9 3 .42185811 0.38020646 14.78 0.0001 

Die l* Depth 27 2.01761618 0.07472653 2.90 0.0001 

Season * Depth 27 9.13703402 0.33840867 13 .15 0.0001 

Side * Season * 

Diel * Distance 

528 84.63035253 0.16028476 6 .23 0.0001 

56 
Table 7a. Number enumerated and percent species composition (in parentheses) by depth strata at Grand Isle 94 from 

August 9 - 10, 1994 from visual point count surveys . 

Depth (m) 

v 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Almaco 

Jack 

1 (1 .5) 1 (0 .1) 

Atlantic 

Spadefish 

Greater 

Amberjack 

1 (1 .0) 5 (6 .8) 11 (13 .3) 6(7 .7) 8 (13 .1) 6(24.0) 37(4.3) 

Bar Jack 6(9.2) 1 (1 .0) 7(0 .8) 

Barracuda 2(l .7) I (I .0) 1(1 .0) 1 (3 .3) 5(0.6) 

Bermuda 

Chub 

16 (12 .5) 8 (12 .3) l (I .0) 8(7.9) 33 (3 .8) 

Bigeye 

Black 

Grouper 

Bluerunner 112 (87.5) 119 (98.3) 40(61-5) 64 (66.0) 43 (42.6) 9(30.0) 387 (44.9) 

Cobia 1 (1 .5) 1 (0 .1) 

Coney 

Grouper 

Creolefish 1 (1 .0) 1 (0 .1) 

Gag 
Table 7a (continued) . Number enumerated and percent species composition (in parentheses) by depth strata at Grand Isle 94 from 

August 9 - 10, 1994 from visual point count surveys . 

Depth (m) 

t-n 

00 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Gray 3 (4 .6) 9(9.3) 2(2.0) 3(10.0) 1 (1 .4) 1 (1 .2) 19(2.2) 

Triggerfish 

Horseye 2(2.1) 2(0.2) 

Jack 

Jack 3 (4 .6) 11 (11 .3) 14(1 .6) 

Crevalle 

Lookdown 35 (34 .7) 35 (4 .1) 

Mangrove 3(4.6) 8(8.2) 10(9.9) 6(20.0) 27(3 .1) 

Snapper 

Marbled 

Grouper 

Ocean 

Triggerfish 

Rainbow 

Runner 

Red 10 (33 .3) 65 (89 .0) 70 (84 .3) 71 (91 .0) 53 (86 .9) 17 (68 .0) 286 (33 .2) 

Snapper 

Scamp 1 (3 .3) 2(2.7) 1 (1 .2) 1 (1 .3) 2 (8 .0) 7(0.8) 

Vermillion 

Snapper 

Yellowfin 

Grouper 

* note if cell empty then no individuals were of that species for that depth level 
Table 7b. Number enumerated and percent species composition (in parentheses) by depth strata at Grand Isle 94 from November 8 - 9, 1994 

from visual point count surveys . 

Depth (m) 

1.0 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Almaco 

Jack 

1 (1 .6) l (O.2) 

Atlantic 

Spadefish 

Greater 

Amberjack 

4(9.1) 7(12.7) 8 (13 .6) 10 (14 .1) 29(5 .4) 

Bar Jack 2(3.2) 4 (7 .3) 2(0 .4) 

Barracuda 2(3.2) 6(7.8) 2(3.2) 2(3.2) 4(9.1) 2(4.5) 2(3.6) 1 (1 .7) 21 (3 .9) 

Bermuda 

Chub 

43 (68 .3) 43 (8 .1) 

Bigeye 

Black 

Grouper 

Bluerunner 14 (22 .2) 68 (88 .3) 34 (54 .8) 31 (50.0) 147 (27 .6) 

Cobia 

Coney 

Grouper 

Creolefish 4(6.5) 3 (4 .8) 2(4.5) 9(l .7) 

Gag 

Gray 

Triggerfish 

1 (1 .6) 1 (1 .3) 2(3.2) 2(3 .2) 3 (6 .8) 18 (40.9) 9 (16.4) 12 (20 .3) 16 (22.5) 64 (12.0) 

Horseye 

Jack 

20 (32 .3) 17 (27 .4) 3 (6 .8) 8 (11 .3) 48(9.0) 
Table 7b (continued) . Number enumerated and percent species composition (in parentheses) by depth strata at Grand Isle 94 from November 8 - 9, 1994 

from visual point count surveys . 

Depth (m) 

oI 

0 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Jack 5 (8 .1) 23 (52.3) 8(18.2) 3 (5 .1) 39(7.3) 

Crevalle 

Lookdown 

Mangrove 6(13 .6) 12 (27 .3) 4(7.3) 2(3.4) 24(4.5) 

Snapper 

Ocean 

Triggerfish 

Rainbow 

Runner 

Red 24 (43 .6) 29 (49.2) 31 (43 .7) 84 (15 .8) 

Snapper 

Scamp 2(2 .6) 2(3 .2) 1 (2 .3) 2(4.5) 5 (9 .1) 4(6.8) 6(8 .5) 22(4.1) 

VermilGon 

Snapper 

Yellowfin 

Grouper 
Table 7c. Number enumerated and percent species composition (in parentheses) by depth strata at Grand Isle 94 from January 31, 1995 

from visual point count surveys . 

Depth (m) 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Almaco 

Jack 

3(0.4) 1 (0 .1) 2(0.3) 2(0 .6) 2(l .7) 8(0.1) 

Atlantic 

Spadefish 

2(0 .6) 2(0.0) 

Greater 

Amberjack 

2(0 .6) 4(0.1) 

Bar Jack 2(0 .2) 2(0.5) 4(0.1) 

Barracuda 2(0 .3) 3 (0 .7) 13 (3 .5) 8(2 .3) 3 (2 .6) 29(0.4) 

Bermuda 

Chub 

2(0.2) 3(0.4) 1 (0 .3) 6(0.1) 

Bigeye 1 (0 .3) 1 (0 .0) 

Black 

Grouper 

1 (0 .3) 1 (0 .0) 

Bluerunner 927 (99 .8) 744 (98.8) 1235 

(99.8) 

835 (99.6) 1074 

(99.7) 

603 (94.1) 389 (88.6) 315 (85 .1) 198 (56.3) 50 (43.5) 6370 

(94.3) 

Cobia 

Coney 

Grouper 

Creolefish 1 (0 .1) 1 (0 .1) 1 (0 .3) 3(0.0) 

Gag 

Gray 

Triggerfish 

1 (0 .1) 1 (0 .1) 1 (0 .1) 7(l .1) 12(2.7) 12(3 .2) 44 (12 .5) 34 (29 .6) 112(l .7) 
Table 7c (continued) . Number enumerated and percent species composition (in parentheses) by depth strata at Grand Isle 94 from January 31, 1995 

from visual point count surveys . 

Death (m) 

N 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Horseye 

Jack 

Jack 

Crevalle 

Lookdown 23 (3 .6) 28 (6 .4) 6(1 .7) 57(0.8) 

Mangrove 2(0.2) 3 (0 .5) 12(3.2) 13 (3 .7) 3 (2 .6) 33 (0 .5) 

Snapper 

Ocean 

Triggerfish 

Rainbow 2(0.3) 2(0.0) 

Runner 

Red 1 (0 .2) 7(l .9) 49 (13 .9) 15 (13 .0) 72(t .1) 

Snapper 

Scamp 1 (0 .2) 4(0.9) 9(2.4) 15 (4 .3) 6(5 .2) 35 (0 .5) 

Vermillion 2(0.5) 8(2 .3) 2(1 .7) 12(0 .2) 

Snapper 

Yellowfin 1 (0 .3) 1 (0 .0) 

Grouper 
Table 7d. Number enumerated and percent species composition (in parentheses) by depth strata at Grand Isle 94 from September 10 - 11, 1995 

from visual point count surveys . 

Death (m) 

w 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Almaco 

Jack 

3 (2 .8) 1 (1 .1) 4 (9 .3) 8(l .4) 

Atlantic 

Spadefish 

Greater 

Amberjack 

4 (9 .3) 4(0 .7) 

Bar Jack 12 (10.7) 12(2.1) 

Barracuda 1 (0 .9) 3 (2 .7) 1 (0 .8) 1 (1 .5) 6(l .1) 

Bermuda 

Chub 

Bigeye 

Black 

Grouper 

Bluerunner 94 (87 .9) 77 (88.5) 92 (82.1) 108 (81 .8) 62 (95 .4) 12 (27.9) 445 (79.5) 

Cobia 

Coney 

Grouper 

Creolefish 12(9.1) 12(2.1) 

Gag 

Gray 

Triggerfish 

2(100.0) 8(7.5) 4(4 .6) 2(l .8) 8 (6 .1) 2 (28.6) 2(100.0) 1 (100 .0) 3 (7 .0) 2(100.0) 34(6.1) 

Horseye 

Jack 

1 (0 .9) 1 (0 .2) 
Table 7d (continued) . Number enumerated and percent species composition (in parentheses) by depth strata at Grand Isle 94 from September 10 - 11, 1995 

from visual point count surveys . 

Depth (m) 

ON 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Jack 5 (71 .4) 5(0.9) 

Crevalle 

Lookdown 

Mangrove 5 (5 .7) 3 (2 .7) 8(l .4) 

Snapper 

Ocean 3 (2 .3) 2(3 .1) 5(0.9) 

Triggerfish 

Rainbow 

Runner 

Red 19 (442) 19(3 .4) 

Snapper 

Scamp 1 (2 .3) 1 (0 .2) 

Vermillion 

Snapper 

Yellowfm 

Grouper 
Table 7e. Number enumerated and percent species composition (in parentheses) by depth strata at Grand Isle 94 from November 14 - 15, 1995 

from visual point count surveys . 

Depth (m) 

o1, 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Almaco 

Jack 

2(0.7) 1 (1 .1) 2(5.9) 1 (1 .7) 2(l .2) 2(0 .6) 10(0.5) 

Atlantic 

Spadefish 

Greater 

Amberjack 

1 (0 .3) 2(0.6) 8(4.0) 4(7 .1) 15(0.8) 

Bar Jack 

Barracuda 7(5.1) 9(3 .1) 10 (10 .5) 7(20.6) 7(12.1) 3 (1 .8) 7 (2 .2) 4(l.2) 2(0.6) 2(l .0) 58(2 .9) 

Bermuda 

Chub 

19 (13 .8) 5(l .7) 24(l .2) 

Bigeye 

Black 

Grouper 

Bluerunner 104 (75 .4) 222 (77 .1) 45 (47 .4) 99 (58 .6) 242 (77 .3) 295 (90 .8) 264 (84 .6) 123 (61 .8) 16 (28 .6) 1410 

(71 .0) 

Cobia 

Coney 

Grouper 

Creolefish 2 (0 .6) 2(0.1) 

Gag 

Gray 

Triggerfish 

2(0.7) 2(l .2) 2 (0 .6) 2(0.6) 1 (0 .5) 9(0 .5) 
Table 7e (continued) . Number enumerated and percent species composition (in parentheses) by depth strata at Grand Isle 94 from November 14 - 15, 1995 

from visual point count surveys . 

Death (m) 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Horseye 8 (5 .8) 46 (16 .0) 33 (34 .7) 21 (61 .8) 14 (24 .1) 39 (23 .1) 40 (12 .8) 12(3 .7) 37 (11 .9) 17 (8 .5) 267 (13 .4) 

Jack 

Jack 1 (0 .3) 5 (8 .6) 5 (3 .0) 3 (1 .0) 1 (0 .3) 15 (0 .8) 

Crevalle 

Lookdown 22 (37 .9) 22(t .1) 

Mangrove 1 (0 .3) 5 (5 .3) 4(11 .8) 9(15 .5) 16(9.5) 13 (4 .2) 48 (2 .4) 

Snapper 

Ocean 

Triggerfish 

Rainbow 1 (1 .1) 1 (0 .1) 

Runner 

Red 2(l .2) 4 (1 .3) 6(l .8) 4 (1 .3) 44 (22 .1) 34 (60 .7) 94(4.7) 

Snapper 

Scamp 1 (0 .6) 3 (0 .9) 2(0.6) 4(2.0) 2(3.6) 12(0.6) 

Vermillion 

Snapper 

Yellowfm 

Grouper 
Table 7f. Number enumerated and percent species composition (in parentheses) by depth strata at Grand Isle 94 from February 13 - 14, 1996 

from visual point count surveys . 

Depth (m) 

o~ 

v 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Almaco 

Jack 

2(0 .9) 1 (0 .5) 1 (0 .5) 1 (0 .4) 5(0.2) 

Atlantic 

Spadefish 

11 (4 .5) 11 (0 .5) 

Greater 

Amberjack 

6(2.8) 6(3.0) 14(5 .1) 15 (5 .4) 22(8 .9) 63 (3 .0) 

Bar Jack 

Barracuda 1 (2 .2) 1 (0 .9) 3 (1 .6) 1 (0 .6) 1 (0 .5) 3 (1 .5) 2(0.7) 12(0.6) 

Bermuda 

Chub 

5(2.2) 5 (0 .2) 

Bigeye 

Black 

Grouper 

Bluerunner 220 (96 .9) 183 (99 .5) 34 (73 .9) 99 (92 .5) 170 (93 .4) 153 (98 .7) 194 (89 .0) 152 (74 .9) 252 (92 .6) 249 (89 .9) 93 (37 .8) 1799 

(85 .0) 

Cobia 

Coney 

Grouper 

Creolefish 1 (0 .5) 1 (0 .0) 

Gag 

Grey 

Triggerfish 

5(10.9) 1 (0 .9) 1 (0 .6) 1 (0 .5) 1 (0 .4) 9(0.4) 
Table 7f (continued) . Number enumerated and percent species composition (in parentheses) by depth strata at Grand Isle 94 from February 13 - 14, 1996 

from visual point count surveys . 

Death (m) 

00 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Horseye 3 (6 .5) 5(4.7) 3 (1 .6) 15 (6 .9) 36 (17.7) 62(2 .9) 

Jack 

Jack 1 (0 .9) 1 (0 .5) 2(l .0) 4(0.2) 

Crevalle 

Lookdown 

Mangrove 6(3 .3) 6(0.3) 

Snapper 

Ocean 

Triggerfish 

Rainbow 3 (6 .5) 3 (0 .1) 

Runner 

Red 12(4.3) 92 (37 .4) 104 (4 .9) 

Snapper 

Scamp 2(l .0) 3 (1 .1) 1 (0 .4) 27 (11 .0) 33 (1 .6) 

Vermillion 

Snapper 

Yellowfin 

Grouper 
Table 7g. Number enumerated and percent species composition (in parentheses) by depth strata at Grand Isle 94 from April 23 - 24, 1996 

from visual point count surveys . 

Depth (m) 

01, 

1.0 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Almaco 

Jack 

1 (0.1) 2(0 .6) 3(0.0) 

Atlantic 

Spadefish 

1 (0 .2) 6(5 .8) 7(0.1) 

Greater 

Amberjack 

1 (0 1) 7(l .0) 11 (1 .3) 4(0.5) 11 (2 .8) 11 (3 .3) 45(0 .7) 

Bar Jack 

Barracuda 3 (7 .3) 4(0.7) 6(0.7) 1 (0 .1) 1 (0 .1) 15(0 .2) 

Bermuda 

Chub 

5(12.2) 4(0.7) 9(0.1) 

Bigeye 

Black 

Grouper 

Bluerunner 33 (80.5) 441 (78 .6) 789 (98 .3) 678 (98.3) 812 (94.3) 653 (92.5) 835 (97.3) 732 (98.7) 358 (92.7) 313 (94.0) 86 (83 .5) 5730 

(94.2) 

Cobia l (O .1) 1 (0 .1) 2(0.0) 

Coney 

Grouper 

Creolefish 

Gag 

Gray 

Triggerfish 

4(0.7) 1 (0 .1) 1 (0 .1) 2(0.5) 8(0 .1) 
Table 7g (continued) . Number enumerated and percent species composition (in parentheses) by depth strata at Grand Isle 94 from April 23 - 24, 1996 

from visual point count surveys . 

Depth (m) 

V 

O 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Horseye 100 (17 .8) 4(0.5) 12(l .7) 44(5 .1) 18(2.5) 2(0.2) 7 (1 .8) 1 (1 .0) 188 (3 .1) 

Jack 

Jack 7(l .2) 3(0.4) 2(0.2) 1 (0 .1) 13(0.2) 

Crevalle 

Lookdown 26(3 .7) 26(0 .4) 

Mangrove 9(1 .0) 3 (0 .4) 12(0 .2) 

Snapper 

Ocean 

Triggerfish 

Rainbow 

Runner 

Red 7 (1 .8) 6(l .8) 8(7.8) 21 (0 .3) 

Snapper 

Scamp 1 (0 .1) 1 (0 .3) 1 (0 .3) 2(l .9) 5(0.1) 

Vermillion 

Snapper 

Yellowfm 

Grouper 
Table 7h. Number enumerated and percent species composition (in parentheses) by depth strata at Grand Isle 94 from September 3-4, 1996 

from visual point count surveys . 

Depth (m) 

v 

r 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Almaco 

Jack 

6(11 .3) 6(0.6) 

Atlantic 

Spadefish 

Greater 

Amberjack 

5(9.4) 1 (5 .6) 6(0.6) 

Bar Jack 

Barracuda 3(l .0) 6(2.7) 3 (3 .6) 1 (0 .5) 1 (1 .9) 14(l .5) 

Bermuda 

Chub 

14(4 .7) 14(l .5) 

Bigeye 

Black 

Grouper 

Bluerunner 278 (94 .2) 143 (64 .7) 50 (59 .5) 134 (62 .3) 35 (64 .8) 36 (67 .9) 676 (71 .9) 

Cobia 2(2.4) 2(0.2) 

Coney 

Grouper 

Creolefish 2(3.7) 2(0.2) 

Gag 

Gray 

Triggerfish 

1 (0 .5) 

I - L 

1 (5 .6) 2(0.2) 
Table 7h (continued) . Number enumerated and percent species composition (in parentheses) by depth strata at Grand Isle 94 from September 3-4, 1996 

from visual point count surveys . 

Depth (m) 

V 

N 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Horseye 24 (28 .6) 45 (20 .9) 5 (9 .3) 74(7 .9) 

Jack 

Jack 59 (26 .7) 2(2.4) 9(4.2) 6(11 .1) 2(3.8) 78(8 .3) 

Crevalle 

Lookdown 22 (10.2) 22(2 .3) 

Mangrove 13 (5 .9) 3 (3 .6) 3 (1 .4) 6(11 .1) 3 (5 .7) 13 (72 .2) 41 (4 .4) 

Snapper 

Ocean 

Triggerfish 

Rainbow 

Runner 

Red 2(11 .1) 2(0.2) 

Snapper 

Scamp 1 (5 .6) 1(0.1) 

Vermillion 

Snapper 

Yellowfin 

Grouper 
Table 7i . Number enumerated and percent species composition (in parentheses) by depth strata at Grand Isle 94 from November 7 - 8, 1996 

from visual point count surveys . 

Depth (m) 

v 

w 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Almaco 1 (2 .6) 1 (0 .2) 

Atlantic 

Spadefish 

4(10.8) 4(0 .6) 

Greater 

Amberjack 

2(16 .7) 3 (18 .8) 10 (27 .0) 15 (2 .4) 

Bar Jack 

Barracuda 2(5.3) 3 (1 .5) 1 (1 .7) 4(4.9) 2(4.5) 3 (3 .8) 3 (10 .7) 3 (9 .7) 1 (8 .3) 6(37.5) 1 (2 .7) 29(4 .6) 

Bermuda 

Chub 

Bigeye 

Black 

Grouper 

Bluerunner 35 (92 .1) 178 (86.8) 45 (76.3) 60 (74.1) 30 (68.2) 60 (76.9) 13 (46.4) 20 (64 .5) 6(50.0) 5 (13.5) 452 (71 .9) 

Cobia 

Coney 

Grouper 

Creolefish 1 (2 .3) 1 (0 .2) 

Gag 

Gray 

Triggerfish 

1 (2 .3) 1 (1 .3) 1 (3 .6) 2(6.5) 1 (6 .3) 6(l .0) 

Horseye 

Jack 

24 (11 .7) 13 (22 .0) 14 (17 .3) 10 (22 .7) 8 (10 .3) 3 (10 .7) 2(16 .7) 1 (6 .3) 75 (11 .9) 
Table 7i (continued) . Number enumerated and percent species composition (in parentheses) by depth strata at Grand Isle 94 from November 7 - 8, 1996 

from visual point count surveys . 

Death fml 

v 

r 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Jack 2(2.5) 2(2.6) 5 (17 .9) 3 (9 .7) 1 (8 .3) 2(12.5) 1 (2 .7) 16(2.5) 

Crevalle 

Lookdown 

Mangrove 1 (1 .2) 4 (5 .1) 3 (10 .7) 3 (9 .7) 11 (1 .7) 

Snapper 

Ocean 

Triggerfish 

Rainbow 

Runner 

Red 1 (6 .3) 16 (43 .2) 17(2.7) 

Snapper 

Scamp 2(12.5) 2(0 .3) 

Vermillion 

Snapper 

Yellowfin 

Grouper 
Table Tj . Number enumerated and percent species composition (in parentheses) by depth strata at Grand Isle 94 from March 9 - 10, 1997 

from visual point count surveys . 

Depth (m) 

v 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Almaco 

Jack 

2(0.6) 1 (0 .1) 2(0.5) 5(0 .1) 

Atlantic 

Spadefish 

Greater 

Amberjack 

1 (0 .3) 1 (0 .2) 1 (0 .2) 1 (0 .2) 8(0.9) 9(1 .2) 15 (3 .6) 36(0 .6) 

Bar Jack 

Barracuda 6(l .8) 11 (2 .4) 7(0.8) 6(l .0) 8(2 .2) 14(2.6) 5 (1 .0) 2(0.4) 5(0.6) 1 (0 .2) 65 (1 .0) 

Bermuda 

Chub 

34 (10 .2) 7(l .5) 41 (0 .7) 

Bigeye 

Black 

Grouper 

Bluerunner 245 (73 .4) 410 (88.0) 851 (97.8) 610 (97.9) 334 (90.0) 507 (94.8) 447 (91 .8) 522 (98.3) 865 (96.6) 684 (92 .8) 348 (84.1) 5823 

(93.0) 

Cobia 

Coney 

Grouper 

Creolefish 3 (0 .5) 3 (0 .6) 6(0.1) 

Gag 1 (0 .3) 1 (0 .2) 1 (0 .2) 3(0.0) 

Gray 

Triggerfish 

1 (0 .2) 2(0.4) 1 (0 .2) 1 (0 .1) 5(0.1) 
Table Tj (continued) . Number enumerated and percent species composition (in parentheses) by depth strata at Grand Isle 94 from March 9 - 10, 1997 

from visual point count surveys . 

Depth (m) 

v 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Horseye 45 (13 .5) 34(7.3) 5(0.6) 2(0.3) 3 (0 .8) 89(l .4) 

Jack 

Jack 2(0.6) 3 (0 .6) 6(0.7) 11 (0 .2) 

Crevalle 

Lookdown 

Mangrove 1 (0 .2) 1 (0 .1) 2(0 .3) 24 (6 .5) 10(1 .9) 26(5 .3) 5(0 .9) 12(l .3) 1(0 .1) 82 (1 .3) 

Snapper 

Ocean 

Triggerfish 

Rainbow 

Runner 

Red 1 (02) 1 (0 .2) 2(0.2) 39(5.3) 47 (11 .4) 90(l .4) 

Snapper 

Scamp 1 (0 .2) 1 (0 .2) 2(0.2) 3(0.4) 7(0.1) 

Vermillion 

Snapper 

Yellowfm 

Grouper 
Table 7k. Number enumerated and percent species composition (in parentheses) by depth strata from all trips to Grand Isle 94 from 

August 1994 - March 1997 from visual point count surveys . 

Depth (m) 

V 

V 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Almaco 

Jack 

5(0.2) 9(0.3) 4(0.1) 2(0.1) 1 (0 .0) 10(0 .4) 2(0.1) 2(0.1) 2(0.1) 7(0.4) 3 (0 .3) 47(0.2) 

Atlantic 

Spadefish 

1 (0 .0) 2(0.1) 21 (2 .4) 24(0.1) 

Greater 

Amberjack 

7(0.2) 13 (0 .5) 31 (12) 31 (1 .3) 55 (2 .3) 60(3 .4) 57(6.5) 254(l .0) 

Bar Jack 2(0.1) 6(0.2) 14(0.5) 1 (0 .0) 6(0.2) 25(0 .1) 

Barracuda 23(l.0) 42(l .4) 30(0.9) 25(0.9) 27(0.9) 28 (1 .1) 21 (0 .8) 27(l .2) 18 (0 .8) 11 (0 .6) 2(0 .2) 254(l .0) 

Bermuda 

Chub 

138 (6 .3) 19(0.6) 8(0.2) 1 (0 .0) 8 (0 .3) 1 (0 .0) 175 (0 .7) 

Bigeye 1 (0 .0) 1(0.0) 

Black 

Grouper 

1 (0 .0) 1 (0 .0) 

Bluerunner 1968 

(89 .7) 

2602 

(87 .2) 

3200 

(93 .9) 

2603 

(91 .1) 

2606 

(89 .3) 

2182 

(88 .1) 

2120 

(84 .9) 

2036 

(86 .8) 

1943 

(81 .7) 

1431 

(80 .3) 

548 (62 .1) 23239 

(87 .0) 

Cobia 3(0 .1) 1 (0 .0) 1 (0 .0) 5(0.0) 

Coney 

Grouper 

Creolefish 5(0.1) 7(0.2) 15 (0 .5) 2(0.1) 5 (0 .2) 1 (0 .0) 1 (0 .0) 36(0.1) 

Gag 1 (0 .0) 1 (0 .0) 1 (0 .1) 3 (0 .0) 

G ray 

Triggerfish 

3 (0 .1) 16(0.5) 16(0 .5) 15 (0 .5) 15 (0 .5) 33 (1 .3) 30(l .2) 34(l .4) 65 (2 .7) 39(2 .2) 2(0.2) 268(l .0) 
Table 7k (continued) . Number enumerated and percent species composition (in parentheses) by depth strata from all trips to Grand Isle 94 from 

August 1994 - March 1997 from visual point count surveys . 

Depth (m) 

V 

00 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Horseye 53 (2 .4) 205 (6 .9) 102 (3 .0) 118 (4 .1) 82(2.8) 65(2.6) 60(2 .4) 48(2 .0) 54(2.3) 18(l .0) 1 (0 .1) 806 (3 .0) 

Jack 

Jack 2(0.1) 70(2 .3) 14(0.4) 28(l .0) 36(l .2) 18(0.7) 14(0 .6) 8(0.3) 2(0.1) 2(0.1) 1 (0 .1) 195 (0 .7) 

Crevalle 

Lookdown 22(0.8) 57 (2 .0) 49(2.0) 28(l .1) 6(0.3) 162 (0 .6) 

Mangrove IS (0 .5) 17(0.5) 21 (0 .7) 57 (2 .0) 54(2.2) 68(2.7) 25 (1 .1) 25 (1 .1) 4(0.2) 286(l .1) 

Snapper 

Ocean 3 (0 .1) 2(0.1) 5(0.0) 

Triggerfish 

Rainbow 2(0.1) 4(0.1) 6(0.0) 

Runner 

Red 13(0.5) 97 (3 .9) 112 (4 .8) 164 (6 .9) 189 (10 .6) 214 (24 .2) 789 (3 .0) 

Snapper 

Scamp 2(0.1) 2(0.1) 1 (0 .0) 7(0.3) 13 (0 .5) 19(0.8) 30(l .3) 18(l .0) 33 (3 .7) 125 (0 .5) 

Vermillion 2(0.1) 8(0.3) 2(0.1) 12(0.0) 

Snapper 

Yellowfin 1 (0 .0) 1 (0 .0) 

Grouper 
Table 8a. Estimated number of fish by species (with 95% confidence intervals) by depth strata at Grand Isle 94 from August 9 - 10, 1994 

from hydroacoustic and visual point count surveys. 

Death (m) 

v 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Almaco 

Jack 

6.5(l .2) 7.7(l .6) 

Atlantic 

Spadefish 

Greater 

Amberj ack 

3 .0 (0 .7) 29.2 (9 .5) 53 .9 (18.8) 24 .8 (6.0) 688.9 

(127 .8) 

331 .7 

(69.0) 

Bar Jack 399 (7 .4) 3 .0(0 .7) 61 .7 (12.8) 

Barracuda 0.7 (0 .2) 3.5 (0 .7) 3 .0(0 .7) 7.1 (1 .7) 46.3 (9 .6) 

Bermuda 

Chub 

6.1 (0 .9) 53.3 (9.9) 3.5 (0 .7) 23 .4 (5 .6) 293.1 

(61 .0) 

Bigeye 

Black 

Grouper 

Bluerunner 42 .8 (6 .0) 41 .3 (9 .3) 266.7 

(49.4) 

232.7 

(43.0) 

126.2 

(30.3) 

64 .6 (15 .7) 3463 .2 

(720 .4) 

Cobia 6.5(l .2) 7.7(l .6) 

Coney 

Grouper 

Creolefish 3.5 (0 .7) 7.7(l .6) 

Gag 
Table 8a (continued). Estimated number of fish by species (with 95% confidence intervals) by depth strata at Grand Isle 94 from August 9 - 10, 1994 

from hydroacoustic and visual point count surveys. 

Death (m) 

00 0 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Gray 199 (3 .7) 32 .8 (6 .1) 5 .9(l .4) 21 .5 (5 .2) 6.0(2 .0) 48 .6(l .7) 169.7 

Triggerfish (35.3) 

Horseye 7.4(l .4) 15 .4 (3 .2) 

Jack 

Jack 199 (3 .7) 39 .8 (7 .4) 123.4 

Crevalle (25.x) 

Lookdown 82.8 (24.7) 316.2 

(65.8) 

Mangrove 199 (3 .7) 289 (5 .3) 29 .3 (7.0) 43 .0 (10.5) 239.1 

Snapper (49.7) 

Marbled 

Grouper 

Ocean 

Triggerfish 

Rainbow 

Runner 

Red 71 .7 (17.4) 382.7 341 .6 292.6 4569.7 2560 .8 

Snapper (124 .9) (118 .9) (71 .2) (848 .0) (532 .7) 

Scamp 7.1 (1 .7) 11 .6 (3 .8) 4.9(l .7) 4.2(l .0) 61 .7 (12.8) 

Vermillion 

Snapper 

Yellowfin 

Grouper 

TOTAL 48 .9 (6 .8) 42 .0 (9 .5) 433 .6 352.6 296.3 215.2 430.0 405.2 321 .5 5258.6 7713 .2 

(80.4) (65.1) (71 .1) (52.3) (140 .3) (141 .1) (78.2) (975 .8) (160 .4) 

* note if cell empty then no individuals were of that species for that depth interval 
Table 8b. Estimated number of fish by species (with 95% confidence intervals) by depth strata at Grand Isle 94 from November 8 - 9, 1994 

from hydroacoustic and visual point count surveys . 

Depth (m) 

00 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Almaco 19 .1 (2 .6) 55.8 (7 .9) 

Jack 

Atlantic 

Spadefish 

Greater 75.8 (13 .9) 294.2 478 .1 733.1 1507 .0 

Amberjack (41 .3) (62 .5) (93 .9) (214 .6) 

Bar Jack 38.3 (5 .2) 169 .1 111 .6 

(23 .7) (15 .9) 

Barracuda 38.3 (5 .2) 32 .1 (6 .0) 2.5 (0 .5) 19.0 (4 .4) 75.8 (13 .9) 56.7 (10 .0) 83 .4 (11 .7) 59.8 (7 .8) 1088.4 

(155 .0) 

Bermuda 816.5 2260.5 

Chub (111 .8) (322) 

Bigeye 

Black 

Grouper 

Bluerunner 265 .4 362 .9 43 .1 (8 .4) 296 .7 7702.6 

(36.3) (68 .3) (68 .1) (1097.0) 

Cobia 

Coney 

Grouper 

Creolefish 5.1 (1 .0) 28.5 (6 .5) 56.7 (10 .0) 474.4 

(67.6) 

Gag 

Gray 19 .1 (2 .6) 5.3 (1 .0) 2.5 (0 .5) 19.0 (4 .4) 56.6 (10 .4) 515 .0 380.0 713.6 1169.9 3349.0 

Triggerfish (90 .8) (53.3) (93 .3) (149 .9) (477 .0) 
Table 8b (continued) . Estimated number of fish by species (with 95% confidence intervals) by depth strata at Grand Isle 94 from November 8 - 9, 1994 

from hydroacoustic and visual point count surveys . 

ilrnth lml 

00 

N 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Horseye 25 .4 (5 .0) 162 .6 56 .6 (10 .4) 587.5 2511 .7 

Jack (37 .3) (75 .3) (357 .7) 

Jack 48.1 (11 .0) 435.4 229 .2 179.3 2037 .3 

Crevalle (80 .0) (40 .4) (23 .4) (290 .2) 

Lookdown 

Mangrove 113.2 343 .7 169.1 119.5 1255 .9 

Snapper (20.8) (60.6) (23 .7) (15.6) (178 .9) 

Ocean 

Triggerfish 

Rainbow 

Runner 

Red 1010.0 1729.6 2272.2 4409.5 

Snapper (141 .7) (226 .2) (291 .1) (628 .0) 

Scamp 10.7 (2 .0) 19 .0 (4 .4) 19 .1 (3 .5) 56.7 (10 .0) 2108.0 239.1 442.0 1144.2 

(29.6) (31 .3) (56.6) (163 .0) 

Vermillion 

Snapper 

Yellowfin 

Grouper 

TOTAL 1195.5 411 .0 78 .7 (15 .4) 593.3 832.5 1259.1 2316.6 3515 .5 5199 .5 2725 .0 4865 .9 27908.0 

(163 .7) (77 .4) (136 .1) (153 .0) (222.1) (324.9) (459 .8) (666 .2) (344 .2) (616 .3) (3974.7) 
Table 8c . Estimated number of fish by species (with 95% confidence intervals) by depth strata at Grand Isle 94 from 

January 31, 1995 from hydroacoustic and visual point count surveys . 

Death (m) 

00 

w 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Almaco 

Jack 

22 .9 (22) 5 .1 (0 .5) 19 .2(l .6) 28 .6 (3 .1) 82 .3 (6 .0) 58 .5 (5 .2) 

Atlantic 

Spadefish 

28 .6 (3 .1) 0.0 (0 .0) 

Greater 

Amberjack 

28 .6 (3 .1) 58 .5 (5 .2) 

Bar Jack 10.6 (0 .9) 27.8 (2 .4) 58 .5 (5 .2) 

Barracuda 19 .2(l .6) 39.0 (3 .4) 172 .8 

(14 .6) 

109.5 

(12 .0) 

125 .9 (9 .1) 234.0 

(20 .7) 

Bermuda 

Chub 

6.9 (0 .7) 22.9 (2 .2) 14.3 (1 .6) 58 .5 (5 .2) 

Bigeye 14 .3 (1 .6) 0.0 (0 .0) 

Black 

Grouper 

14 .3 (1 .6) 0.0 (0 .0) 

Bluerunner 3420 .8 

(345 .2) 

5658.8 

(551 .7) 

5109.0 

(482 .0) 

5278.1 

(453 .5) 

5833.4 

(496 .9) 

6031 .9 

(498.1) 

4931 .3 

(424 .4) 

4202 .4 

(355 .5) 

2681.5 

(294.2) 

2106.7 

(152.3) 

55161 .5 

(4879.3) 

Cobia 

Coney 

Grouper 

Creolefish 5 .1 (0 .5) 5 .3 (0 .5) 14 .3 (1 .6) 0.0 (0 .0) 

Gag 

Gray 

Triggerfish 

5.7 (0 .6) 5 .1 (0 .5) 5 .9 (0 .5) 70 .5 (5 .8) 150.3 

(12 .9) 

158.0 

(13 .4) 

595.4 

(65 .3) 

1433.6 

(103 .7) 

994 .4 

(88 .0) 
Table 8c (continued) . Estimated number of fish by species (with 95% confidence intervals) by depth strata at Grand Isle 94 from 

January 31, 1995 from hydroacoustic and visual point count surveys . 

Depth (m) 

00 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Horseye 

Jack 

Jack 

Crevalle 

Lookdown 230.8 356.2 81 (8 .9) 468.0 

(19 .1) (30 .7) (41 .4) 

Mangrove 11 .7(l .0) 32 .1 (2 .6) 158 .0 176.2 125 .9 (9 .1) 292.5 

Snapper (13 .4) (19.3) (25 .9) 

Ocean 

Triggerfish 

Rainbow 17.2(l .7) 0.0 (0 .0) 

Runner 

Red 11 .1 (1 .0) 93.8 (7 .9) 662.0 629.6 643 .5 

Snapper (72.9) (45 .5) (56 .9) 

Scamp 12 .8(l .1) 50 .1 (4 .3) 118.5 204 .8 251 .8 292.5 

(10 .0) (22.5) (182) (25 .9) 

Vermillion 24.7 (2 .1) 109.5 82.3 (6 .0) 117.0 

Snapper (12.0) (10.3) 

Yellowfin 14 .3 (1 .6) 0.0 (0 .0) 

Grouper 

TOTAL 3427 .7 5727 .5 5119 .2 5299 .3 5851 .0 6410 .1 5565 .8 4938 .2 4762.9 4843 .1 6551 .1 58495 .8 

(345 .9) (558 .4) (483 .0) (455 .3) (498 .4) (529 .3) (479 .0) (417 .7) (522 .5) (350 .2) (534 .5) (5174.2) 
Table 8d. Estimated number of fish by species (with 95% confidence intervals) by depth strata at Grand Isle 94 from 

September 10 - 11, 1995 from hydroacoustic and visual point count surveys . 

Depth (m) 

00 

k-n 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Almaco 25 .1 (3 .1) 1 .5 (0 .6) 153.1 119.0 

Jack (13 .0) (16 .4) 

Atlantic 

Spadefish 

Greater 153.1 59 .5 (8 .2) 

Amberjack (13 .0) 

Bar Jack 24.6 (4 .2) 178 .5 

(24.5) 

Barracuda 8.1 (1 .0) 6.2(l .1) 2.7 (0 .6) 5.6 (0 .8) 93.5 (12 .9) 

Bermuda 

Chub 

Bigeye 

Black 

Grouper 

Bluerunner 788 .5 120 .8 188.8 279.6 356.9 459.3 6757 .4 

(95 .9) (46 .2) (32 .3) (60 .4) (53 .7) (39 .1) (929 .1) 

Cobia 

Coney 

Grouper 

Creolefish 31 .1 (6 .7) 178.5 

(24 .5) 

Gag 

Gray 189 .5 67.3 (8 .2) 6.3 (2 .4) 4.1 (0 .7) 20 .8 (4 .5) 145 .6 524.8 1002.8 115.2 (9 .8) 1568.4 518 .5 

Triggerfish (20 .3) (20.1) (72 .9) (126.2) (244 .0) (71 .3) 
Table 8d. Estimated number of fish by species (with 95% confidence intervals) by depth strata at Grand Isle 94 from 

September 10 - 11, 1995 from hydroacoustic and visual point count surveys . 

Depth (m) 

00 all 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Horseye 8.1 (1 .0) 17 .0 (2 .3) 

Jack 

Jack 363.4 76.5 (10 .5) 

Crevalle (50 .2) 

Lookdown 

Mangrove 7.8 (3 .0) 6 .2(l .1) 119.0 

Snapper (16 .4) 

Ocean 7.9(l .7) 11 .6(l .7) 76.5 (10 .5) 

Triggerfish 

Rainbow 

Runner 

Red 727 .7 289.0 

Snapper (61 .9) (39.7) 

Scamp 37.9 (3 .2) 17 .0 (2 .3) 

Vermillion 

Snapper 

Yellowfin 

Grouper 

TOTAL 189 .5 897.0 136.5 230.0 341 .8 374.1 509.0 524.8 1002 .8 1646 .4 1568 .4 8499 .9 

(20 .3) (109.1) (52 .2) (39.3) (73 .8) (56.3) (70 .3) (72 .9) (126.2) (140 .1) (244.0) (1168 .7) 
Table 8e. Estimated number of fish by species (with 95% confidence intervals) by depth strata at Grand Isle 94 from 

November 14 - 15, 1995 from hydroacoustic and visual point count surveys . 

Depth (m) 

00 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Almaco 

Jack 

19.9 (3 .0) 16.5 (3 .7) 97.3 (23 .7) 31 .2 (4 .7) 51 .4 (8 .1) 29.8 (4 .2) 219 .8 

(352) 

Atlantic 

Spadefish 

Greater 

Amberjack 

14 .9 (2 .1) 20 .2 (2 .9) 168.8 

(23 .4) 

283.1 

(56 .3) 

351 .7 

(56 .4) 

Bar Jack 

Barracuda 279.8 

(37 .3) 

88.2 (13 .4) 157.1 

(35 .1) 

339.6 

(82 .9) 

222.4 

(33 .5) 

77.0 (12.2) 82.7 (12 .7) 59.5 (8 .5) 20 .2 (2 .9) 42.2 (5 .8) 1274 .9 

(204 .3) 

Bermuda 

Chub 

757.1 

(101 .0) 

48.4 (7 .4) 527.6 

(84 .5) 

Bigeye 

Black 

Grouper 

Bluerunner 4136.4 

(552.1) 

2194.7 

(333 .7) 

709.2 

(158.3) 

2507 .6 

(395 .7) 

2904 .6 

(447 .9) 

4503.9 

(642.2) 

2844.0 

(413 .1) 

2608 .3 

(360 .8) 

1140.3 

(226 .7) 

3121 .3 

(5001 .5) 

Cobia 

Coney 

Grouper 

Creolefish 22.5 (3 .5) 44.0 (7 .0) 

Gag 

Gray 

Triggerfish 

19 .9 (3 .0) 51 .4 (8 .1) 22 .5 (3 .5) 29 .8 (4 .2) 21 .1 (2 .9) 219 .8 

(35 .2) 
Table 8e (continued) . Estimated number of fish by species (with 95% confidence intervals) by depth strata at Grand Isle 94 from 

November 14 - 15, 1995 from hydroacoustic and visual point count surveys . 

Depth (m) 

00 

00 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Horseye 318.2 455.5 519 .2 1018.9 442.9 988 .5 481 .0 183 .5 400.0 358.8 5891 .0 

Jack (42 .5) (69 .2) (115 .9) (248.6) (66 .8) (156.0) (58 .1) (26.2) (58 .1) (49.6) (943 .9) 

Jack 8 .5 (1 .3) 158.1 128 .4 37 .6 (5 .8) 10.1 (1 .5) 351 .7 

Crevalle (23 .8) (20 .3) (56.4) 

Lookdown 696.5 483 .6 

(105 .0) (77 .5) 

Mangrove 8 .5 (1 .3) 79.3 (17 .7) 194.5 284.9 406 .5 157.8 1055 .1 

Snapper (47.5) (42 .9) (64 .1) (24 .3) (169 .1) 

Ocean 

Triggerfish 

Rainbow 16 .5 (3 .7) 44.0 (7 .0) 

Runner 

Red 51 .4 (8 .1) 48.8 (7 .5) 89.3 (12 .7) 43.7 (6 .3) 932.8 2420.2 2066 .2 

Snapper (129.0) (481 .0) (331 .1) 

Scamp 25.7 (4 .1) 44 .6 (6 .4) 20.2 (2 .9) 84 .4 (11 .7) 143.5 263 .8 

(28 .5) (42 .3) 

Vermillion 

Snapper 

Yellowfin 

Grouper 

TOTAL 5485.9 2846.6 1496 .3 1648.7 1837.8 4279.2 3757.6 4960.2 3361 .7 4220.6 3987.1 43962.5 

(732 .2) (432.8) (333 .9) (402 .3) (277.0) (675 .2) (579 .4) (707.3) (488 .3) (583 .8) (792 .5) (7044.3) 
Table 8f. Estimated number of fish by species (with 95% confidence intervals) by depth strata at Grand Isle 94 from 

February 13 - 14, 1996 from hydroacoustic and visual point count surveys . 

Death (m) 

00 

110 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Almaco 

Jack 

12.0 (1 .5) 4.7 (0 .8) 12.5(t .0) 43.4 (3 .6) 

Atlantic 

Spadefish 

108 .5 (8 .9) 

Greater 

Amberjack 

69 .9 (5 .6) 93 .9 (6 .3) 180.4 

(10 .7) 

134.2 (6 .7) 651 .0 

(53 .4) 

Bar Jack 

Barracuda 11 .8 (2 .2) 5 .0 (0 .8) 14.2(l .2) 8.1 (0 .7) 12.5(l .0) 47.0 (3 .2) 24 .8 (1 .5) 130.2 

(10.7) 

Bermuda 

Chub 

29.2 (3 .7) 43.4 (3 .6) 

Bigeye 

Black 

Grouper 

Bluerunner 1287.9 

(164 .0) 

938.1 

(160.1) 

395 .7 

(74 .1) 

511 .6 

(86 .3) 

831 .4 

(68 .1) 

1338.4 

(115 .6) 

2221 .7 

(115 .6) 

2345 .4 

(157 .5) 

3276.2 

(194.6) 

2233 .9 

(111 .1) 

18446.2 

(1512.8) 

Cobia 

Coney 

Grouper 

Creolefish 15 .7(l .1) 0 .0 (0 .0) 

Gag 

Gray 

Triggerfish 

53.4 (10 .9) 5 .0 (0 .8) 8.1 (0 .7) 15 .7 (1 .1) 14 .2 (0 .8) 86 .8 (7 .1) 
Table 8f (continued) . Estimated number of fish by species (with 95% confidence intervals) by depth strata at Grand Isle 94 from 

February 13 - 14, 1996 from hydroacoustic and visual point count surveys . 

Depth (m) 

0 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Horseye 34.8 (6 .5) 26.0 (4 .4) 14 .2(l .2) 172.2 554 .3 629.3 

Jack (13 .9) (37 .2) (51 .6) 

Jack 5.0 (0 .8) 12.5(l .0) 31 .3 (2 .1) 43 .4 (3 .6) 

Crevalle 

I,ookdown 

Mangrove 29.4 (2 .4) 65.1 (5 .3) 

Snapper 

Ocean 

Triggerfish 

Rainbow 34.8 (6 .5) 21 .7(l .8) 

Runner 

Red 106.9 (5 .3) 1063 .4 

Snapper (g~~2) 

Scamp 31 .3 (2 .1) 38.9 (2 .3) 9.9 (0 .5) 347.2 

(28.5) 

Vermillion 

Snapper 

Yellowfm 

Grouper 

TOTAL 1329.1 942.8 535.5 553 .1 890.1 1356.0 2496.3 3131 .4 3538.1 2484.9 21701 .4 

(1692) (160.9) (100.3) (93 .3) (72 .9) (117 .1) (201 .2) (210.3) (210 .1) (123.6) (1779.8) 
Table 8g. Estimated number of fish by species (with 95% confidence intervals) by depth strata at Grand Isle 94 

from April 23 - 24, 1996 from hydroacoustic and visual point count surveys . 

Depth (m) 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Almaco 

Jack 

0.1 (0 .0) 0.6 (0 .1) 0 .0 (0 .0) 

Atlantic 

Spadefish 

0.2 (0 .1) 10 .5 (2 .7) 2.38 (0 .7) 

Greater 

Amberjack 

0.0 (0 .0) 1 .5 (0 .5) 1 .6 (0 .3) 2.5 (0 .5) 14 .4 (5 .1) 3 .3 (0 .5) 16 .7 (5 .2) 

Bar Jack 

Barracuda 30.2(21 .2) 0.5 (0 .2) 1 .8 (0 .8) 0.0 (0 .0) 0.5 (0 .1) 4.8 (1 .5) 

Bermuda 

Chub 

50.5 (212) 0.5 (0 .2) 2.4 (0 .7) 

Bigeye 

Black 

Grouper 

Bluerunner 333 .4 

(140.2) 

59.4 (19 .8) 248.7 

(106.6) 

40.0 (0 .6) 34.3 (4 .5) 136.4 

(43 .9) 

116.5 

(20 .6) 

491 .5 

(106 .0) 

476 .4 

(169 .4) 

94 .2 (14 .7) 151 .0 

(39 .2) 

2242.0 

(697 .6) 

Cobia 0.0 (0 .0) 0.0 (0 .0) 0.0 (0 .0) 

Coney 

Grouper 

Creolefish 

Gag 

Gray 

Triggerfish 

0.5 (02) 0.3 (0 .1) 0.5(l .1) 2.6 (0 .9) 2.4 (0 .7) 
Table 8g (continued) . Estimated number of fish by species (with 95% confidence intervals) by depth strata at Grand Isle 94 

from April 23 - 24, 1996 from hydroacoustic and visual point count surveys . 

Depth (m) 

N 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Horseye 13 .5 (4 .5) 1 .3 (0 .5) 0.7 (0 .1) 1 .9 (0 .2) 3 .7(l .2) 0.2 (0 .0) 9.3 (3 .3) 1 .8 (0 .5) 73 .8 (23 .0) 

Jack 

Jack 0.9 (0 .3) 1 .0 (0 .4) 0.1 (0 .0) 0 .1 (0 .0) 4.8(l .5) 

Crevalle 

Lookdown 5 .5 (1 .8) 9.5 (3 .0) 

Mangrove 1 .2 (0 .2) 2.0 (0 .4) 4.8(l .5) 

Snapper 

Ocean 

Triggerfish 

Rainbow 

Runner 

Red 9 .3 (3 .3) 1 .8 (0 .3) 14.1 (3 .7) 7.1 (2 .2) 

Snapper 

Scamp 0.1 (0 .0) 1 .5 (0 .5) 0.3 (0 .0) 3 .4 (0 .9) 2.4 (0 .7) 

Vermillion 

Snapper 

Yellowfin 

Grouper 

TOTAL 414.1 75.6 (25 .2) 253.0 40.7 (6 .7) 36 .4 (4 .8) 147 .5 119.7 498.0 513 .9 100.2 180.8 2380.0 

(174 .1) (108 .4) (47 .5) (21 .2) (107.4) (182.7) (15 .6) (46 .9) (740.5) 
Table 8h. Estimated number of fish by species (with 95 % confidence intervals) by depth strata at Grand Isle 94 

from September 3 - 4, 1996 from hydroacoustic and visual point count surveys . 

Depth (m) 

w 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Almaco 

Jack 

22 .6 (8 .0) 27 .7 (8 .3) 

Atlantic 

Spadefish 

Greater 

Amberjack 

18 .8 (6 .6) 5 .6 (2 .1) 27.7 (8 .3) 

Bar Jack 

Barracuda 173 .6 (3 .6) 12.5(l .9) 14.4 (2 .0) 1 .3 (0 .4) 3 .8 (1 .3) 69.4 (20 .9) 

Bermuda 

Chub 

81 .6 (17 .1) 69 .4 (20 .9) 

Bigeye 

Black 

Grouper 

Bluerunner 1635.6 

(343 .4) 

299.4 

(44 .5) 

237.5 

(33 .9) 

163.9 

(51 .0) 

97.3 (31 .4) 135.7 

(47 .8) 

3324.5 

(999 .5) 

Cobia 9.6(l .4) 9.2 (2 .8) 

Coney 

Grouper 

Creolefish 5.6(l .8) 9.2 (2 .8) 

Gag 

Gray 

Triggerfish 

1 .3 (0 .4) 5 .6 (2 .1) 9.2 (2 .8) 
Table 8h (continued) . Estimated number of fish by species (with 95 % confidence intervals) by depth strata at Grand Isle 94 

from September 3 - 4, 1996 from hydroacoustic and visual point count surveys . 

Depth (m) 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Horseye 114.1 55 .0 (17 .1) 14 .0 (4 .5) 365 .3 

Jack (16.3) (109 .8) 

Jack 123 .6 9.6(l .4) 11 .1 (3 .4) 16 .7 (5 .4) 7 .6 (2 .7) 383.8 

Crevalle (18.4) (115 .4) 

Lookdown 26.8 (8 .4) 106.3 

(32 .0) 

Mangrove 27.3 (4 .1) 14 .4 (2 .0) 3 .7 (1 .1) 16 .7 (5 .4) 11 .4 (4 .0) 72 .6 (26 .6) 203 .4 

Snapper (61 .2) 

Ocean 

Triggerfish 

Rainbow 

Runner 

Red 11 .2 (4 .1) 9.2 (2 .8) 

Snapper 

Scamp 5 .6 (2 .1) 4.6(l .4) 

Vermillion 

Snapper 

Yellowfin 

Grouper 

TOTAL 1736 .3 462.8 399.1 263.1 150 .1 199.8 100.6 152.8 284.5 163 .5 281 .1 4623 .8 

(364 .5) (68.8) (56 .9) (81 .9) (48.5) (70 .4) (36.9) (76.4) (161 .8) (75.8) (123 .0) (225 .2) 
Table 8i . Estimated number of fish by species (with 95% confidence intervals) by depth strata at Grand Isle 94 

from November 7 - 8, 1996 from hydroacoustic and visual point count surveys . 

Depth (m) 

-10 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Almaco 

Jack 

142.6 

(19.0) 

87 .9 (14.1) 

Atlantic 

Spadefish 

430.6 

(85 .6) 

263 .8 

(42 .3) 

Greater 

Amberjack 

561 .4 

(81 .5) 

793.5 

(109 .8) 

1076.5 

(214.0) 

1055 .1 

(169 .1) 

Bar Jack 

Barracuda 290.8 

(38 .8) 

42.7 (6 .5) 25.4 (5 .7) 80.8 (19 .7) 82.7 (12 .5) 162.6 

(25 .7) 

402.1 

(62 .0) 

481 .1 

(68 .6) 

279.0 

(40 .5) 

1582.7 

(218 .9) 

107 .7 

(21 .4) 

2022 .3 

(324 .0) 

Bermuda 

Chub 

Bigeye 

Black 

Grouper 

Bluerunner 5052.5 

(674 .4) 

2470.8 

(375 .7) 

1141 .7 

(254 .0) 

1221 .7 

(188 .9) 

1253.4 

(188 .9) 

3290.7 

(519 .2) 

1743.5 

(268.8) 

3199.3 

(456 .2) 

1680.9 

(244 .2) 

538.3 

(107.0) 

31609.0 

(5064.9) 

Cobia 

Coney 

Grouper 

Creolefish 42.3 (6 .4) 879 (14.1) 

Gag 

Gray 

Triggerfish 

42 .3 (6 .4) 55.6 (8 .8) 135 .3 

(20 .9) 

322.4 

(46 .0) 

265.9 

(36 .8) 

439.6 

(70 .4) 
Table 8i (continued) . Estimated number of fish by species (with 95% confidence intervals) by depth strata at Grand Isle 94 

from November 7 - 8, 1996 from hydroacoustic and visual point count surveys . 

Depth (m) 

110 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Horseye 333 .1 329.2 285 .2 417.2 440.8 402.1 561 .4 265.9 5231 .5 

Jack (50.6) (73 .5) (69.6) (62.9) (69.5) (62.0) (81 .5) (36.8) (838 .3) 

Jack 41 .2 (10 .1) 111 .3 672.6 481 .1 279.0 527.6 107.7 1099.1 

C revalle (17.6) (103 .7) (68 .6) (40 .5) (73 .0) (21 .4) (176.1) 

Lookdown 

Mangrove 19.8 (4 .8) 218 .2 402.1 481 .1 747 .4 

Snapper (34 .4) (62 .0) (68 .6) (119 .8) 

Ocean 

Triggerfish 

Rainbow 

Runner 

Red 265.9 1722.4 1187.0 

Snapper (36 .8) (342 .4) (190.2) 

Scamp 527.6 131 .9 

(73 .0) (21 .1) 

Vermillion 

Snapper 

Yellowfin 

Grouper 

TOTAL 5485 .9 2846 .6 1496 .3 1648 .7 1837 .8 4279.2 3757 .6 4960 .2 3361 .7 4220 .6 3987 .1 43962.5 

(732 .2) (432.8) (333 .9) (402 .3) (277.0) (675 .2) (579 .4) (707 .3) (488.3) (583 .8) (792 .5) (7044.3) 
Table 8j . Estimated number of fish by species (with 95% confidence intervals) by depth strata at Grand Isle 94 

from March 9 - 10, 1997 from hydroacoustic and visual point count surveys . 

Depth (m) 

1.0 

V 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Almaco 

Jack 

12 .9(t .0) 6.8 (0 .5) 50 .5 (2 .7) 67 .0 (4 .7) 

Atlantic 

Spadefish 

Greater 

Amberjack 

18 .3 (1 .3) 2 .9 (0 .2) 2.9 (0 .3) 4.6 (0 .5) 37.2 (3 .0) 81 .1 (6 .1) 368 .7 

(19 .7) 

402.2 

(282) 

Bar Jack 

Barracuda 38.6 (3 .0) 55.1 (3 .7) 55.7 (4 .9) 14.7 (2 .8) 134 .1 (9 .8) 37 .5 (2 .7) 14 .6 (1 .3) 9.2 (0 .9) 24.8 (2 .0) 20.2(l .1) 670.2 

(47 .0) 

Bermuda 

Chub 

219.0 

(16 .9) 

34.5 (2 .3) 469.2 

(32 .9) 

Bigeye 

Black 

Grouper 

Bluerunner 1575 .8 

(121 .9) 

2021 .7 

(136.2) 

6813 .5 

(597.6) 

1441 .6 

(223 .2) 

5487.8 

(399 .4) 

1367 .1 

(99 .7) 

1336.0 

(121 .5) 

2255 .4 

(222 .8) 

3990.4 

(324 .6) 

6268 .5 

(469 .9) 

8495 .4 

(460 .4) 

62334.8 

(4367.4) 

Cobi 

Coney 

Grouper 

Creolefish 7.3 (1 .1) 8 .7 (0 .8) 67.0(4.7) 

Gag 18 .3 (1 .3) 2 .9 (2 .6) 20.2(l .1) 0.0 (0 .0) 

Gray 

Triggerfish 

2.9 (0 .2) 5 .8 (0 .5) 4.6 (0 .5) 4.1 (0 .3) 67.0 (4 .7) 
Table 8j (continued) . Estimated number of fish by species (with 95 % confidence intervals) by depth strata at Grand Isle 94 

from March 9 - 10, 1997 from hydroacoustic and visual point count surveys . 

Depth (m) 

110 

00 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Horseye 289 .8 167.7 41 .8 (3 .7) 4.4 (0 .7) 48.8 (3 .6) 938.4 

Jack (22 .4) (11 .3) (65 .7) 

Jack 12.9(l .0) 13.8 (0 .9) 48.8 (4 .3) 134 .1 (9 .4) 

Crevalle 

Lookdown 

Mangrove 4.6 (0 .3) 7.0 (0 .6) 4.4 (0 .7) 396 .3 27 .4 (2 .0) 77.1 (7 .0) 20.6 (2 .0) 53 .7 (4 .4) 6.8 (0 .5) 871 .3 

Snapper (28.8) (61.0) 

Ocean 

Triggerfish 

Rainbow 

Runner 

Red 2.9 (0 .2) 2 .9 (0 .3) 8 .3 (0 .7) 358 .0 1151 .6 938.4 

Snapper (26.8) (62.4) (65.7) 

Scamp 2.9 (0 .2) 2.9 (0 .3) 8 .3 (0 .7) 13.5 (2 .0) 67 .0 (4 .7) 

Vermillion 

Snapper 

Yellowfin 

Grouper 

TOTAL 2146.9 2297.4 6966 .8 1472.5 6097.6 1442.1 1455 .3 2294 .4 4130.9 6754.8 10101 .6 67026.7 

(166 .1) (154.8) (611 .0) (228 .0) (443 .8) (105 .2) (132.3) (226 .7) (336 .0) (506.4) (547.5) (4696.1) 
Table 8k. Estimated number of fish by species (with 95% confidence intervals) by depth strata from all trips to Grand Isle 94 

from August 1994 - March 1997 from hydroacoustic and visual point count surveys . 

Depth (m) 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Almaco 

Jack 

5 .7 (0 .4) 4 .1 (0 .3) 1 .4 (0 .1) 1 .3 (0 .1) 0.0 (0 .0) 8.0 (0 .5) 2.3 (0 .1) 2.8 (0 .2) 3 .3 (0 .2) 13 .1 (0 .7) 11 .9 (0 .7) 57 .9 (3 .6) 

Atlantic 

Spadefish 

0 .0 (0 .0) 3 .3 (0 .2) 95 .1 (5 .5) 29 .0 (1 .8) 

Greater 

Amberjack 

2 .8 (0 .2) 10 .0(0.7) 27 .3 (1 .6) 37.0 (2 .0) 76.5(4.2) 111 .2 (5 .7) 257.4 

(14 .8) 

289.5 

(18 .1) 

Bar Jack 2 .9(0.2) 2.8 (0 .2) 6.5 (0 .5) 0.0 (0 .0) 4 .5 (0 .3) 29 .0 (1 .8) 

Barracuda 28.5 (1 .8) 19.3 (1 .4) 12 .8(l .0) 11 .7 (0 .9) 12.7 (0 .9) 22.0 (1 .5) 18 .2(l .0) 34.1 (1 .9) 26.6(l .4) 19 .6(l .0) 7 .9 (0 .5) 289 .5 

(18 .1) 

Bermuda 

Chub 

179.6 

(11 .2) 

8 .3 (0 .6) 2.8 (0 .2) 0.0 (0 .0) 4 .2 (0 .3) 0 .0 (0 .0) 202 .7 

(12 .6) 

Bigeye 0 .0 (0 .0) 0.0 (0 .0) 

Black 

Grouper 

0.0 (0 .0) 0.0 (0 .0) 

Bluerunner 2557 .3 

(159 .0) 

1201 .4 

(87 .7) 

1336.5 

(105 .2) 

1183.4 

(92.6) 

1255.3 

(92 .9) 

1760.8 

(119 .6) 

1930.0 

(111 .4) 

2468 .8 

(135.5) 

2718.7 

(148.0) 

2625.6 

(134.3) 

24595.5 

(141 .6) 

25188.4 

(1571 .2) 

Cobia 1 .4 (0 .1) 0 .0 (0 .0) 0 .0 (0 .0) 0.0 (0 .0) 

Coney 

Grouper 

Creolefish 1 .4 (0 .1) 2.6 (0 .2) 7.0 (0 .5) 2.0(0 .1) 4.5 (0 .3) 0 .0 (0 .0) 0.0 (0.0) 29 .0(1 .8) 

Gag 0.0 (0 .0) 0.0 (0 .0) 4 .0 (0 .2) 0 .0(0 .0) 
Table 8k (continued) . Estimated number of fish by species (with 95% confidence intervals) by depth strata from all trips to Grand Isle 94 

from August 1994 - March 1997 from hydroacoustic and visual point count surveys . 

Death (ml 

0 0 

Species 0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55 0-60 

Gray 2.9 (0 .2) 6.9 (0 .5) 7 .1 (0 .6) 6.5 (0 .5) 7.0 (0 .5) 26.0 (1 .8) 27 .3(l .6) 39.8 (2 .2) 89.8 (4 .9) 71 .9 (3 .7) 7.9 (0 .5) 289.5 

Triggerfish (18.1) 

Horseye 68.4 (4 .3) 95.1 (6 .9) 42.7 (3 .4) 53.3 (4 .2) 39 .4 (2 .9) 52.0 (3 .5) 54.6 (3 .1) 56.9 (3 .1) 76 .5 (4 .2) 32.7 (1 .7) 4.0 (0 .2) 868 .6 

Jack (54 .2) 

Jack 2.9(0.2) 31 .7 (2 .3) 5 .7 (0 .4) 13 .0 (1 .0) 16 .9(l .2) 14.0 (1 .0) 13 .6 (0 .8) 85 .3 (0 .5) 3.3 (0 .2) 3 .3 (0 .2) 4.0 (0 .2) 202 .7 

Crevalle (12.6) 

Lookdown 10 .4 (0 .8) 28 .1 (2 .1) 40.0 (2 .7) 25.0 (1 .4) 10 .0 (0 .5) 173 .7 

(10.8) 

Mangrove 6.9 (0 .5) 7 .1 (0 .6) 9.1 (0 .7) 28.1 (2 .1) 44.0 (3 .0) 61 .4 (3 .5) 31 .3 (1 .7) 36 .6 (2 .0) 6.5 (0 .3) 318.5 

Snapper (19 .9) 

Ocean 1 .4 (0 .1) 2 .0 (0 .1) 0.0 (0 .0) 

Triggerfish 

Rainbow 1 .4 (0 .1) 1 .4 (0 .1) 0 .0 (0 .0) 

Runner 

Red 10.9 (0 .7) 88.7 (5 .1) 136.5 (7 .5) 229.6 346.6 958.5 868.6 

Snapper (12 .5) (17 .7) (55 .2) (54 .2) 

Scamp 1 .4 (0 .1) 1 .3 (0 .1) 0.0 (0.0) 6 .0 (0 .4) 11 .4 (0 .7) 22 .8 (1 .2) 43.3 (2 .4) 32 .7 (1 .7) 146.5 (8 .4) 144 .8 (9 .0) 

Vermillion 2.8 (0 .2) 10.0 (0 .5) 3 .3 (0 .2) 0.0 (0 .0) 

Snapper 

Yellowfin 0.0 (0 .0) 0.0 (0 .0) 

Grouper 

TOTAL 2850 .9 1377 .8 1423 .3 1299 .0 1405 .7 1998 .6 2273 .3 2844 .2 3327 .7 3269 .8 3960 .6 28952.2 

(177.3) (100 .6) (112.0) (101 .7) (104 .0) (135 .8) (131 .2) (156 .1) (181 .2) (167 .3) (228 .0) (1806.0) 
Table 9. RBD ANOVA (block on platform side) results of vertical log 

fish density (log(number of fish/m 3) with platform side, year, season, time of 

day, depth, current vectors, temperature, salinity, dissolved oxygen and selected 

interactions at the GC18 petroleum platform . 

Source DF SS MS F Prob > F 

Model 90 2.0053289 0.0222814 20.93 0.0001 

Error 5985 6.3729412 0.0010648 

Corrected 

Total 

6075 8.3782700 

R-Square C .V. Root MSE LDENSITY 

Mean 

0.476178 252.0003 0 .0284 0.0113 

Variables DF Type III SS Mean Square F Value Pr > F 

Side 3 0 .2220276 0 .0740092 69 .50 0.0001 

Year 3 0 .0115176 0.0382392 3 .61 0.0128 

Season 3 0.0352252 0.0117751 11 .06 0.0001 

Diel 3 0.0030421 0.0010140 1 .25 0.2884 

Depth 10 0.3454644 0.0354464 33 .29 0.0001 

Temperature 1 0.0051256 0.0051256 4.81 0 .0283 

Dissolved 

oxygen 

1 0.0051131 0.0051131 5.37 0 .0206 

Salinity 1 0.0010461 0.0010461 0.98 0.3216 

North vector 1 0.0011174 0.0011174 1 .05 0.3057 

East vector 1 0.0007499 0.0007499 0.07 0.4014 

North squared 

vector 

1 0.0079050 0.0079050 7.42 0.0065 

East squared 

vector 

1 0.0005933 0.0005933 0.56 0.4554 

North * East 1 0.0035980 0.0035680 3 .38 0.0661 

Diel * Depth 30 0.1210778 0.0040359 3 .79 0.0001 

Season * Death 30 0. 3375548 0.0112518 10.57 ~ 0 .0001 

101 
Table 10. RBD ANOVA (block on platform side) results of horizontal log 

relative fish density (log(number of fish/m 3) with platform side, year, season, time 

of day, distance from the platform and selected interactions at the GC 18 petroleum platform . 

Source DF SS MS F Prob > F 

Model 1159 84 .788167 0.073156 5 .68 0 .0001 

Error 4870 62 .705195 0.012876 

Corrected 

Total 

6029 147.493362 

R-Square C.V . Root MSE LDENSITY 

Mean 

0.574861 180.3045 0.1135 0 .0629 

Variables DF Type III SS Mean 

Square 

F Value Pr > F 

Side 3 21 .033569 7 .011190 544.52 0.0001 

Year 3 0.080941 0.026980 2 .10 0 .0986 

Season 3 3 .245408 1 .081803 84.02 0.0001 

Diel 3 1 .460569 0.486856 37.81 0.0001 

Depth 9 0 .166086 0 .018454 1 .43 0.1676 

Diel * Depth 27 1 .195570 0.044280 3.44 0.0001 

Year * 

Season 

1 0.35030 0.035030 2 .72 0.0991 

Side * Year 

* Season 

Diel * Depth 

1110 50.150390 0.045181 3 .51 0 .0001 

102 
Table 11 a. Number enumerated and percent species composition (in parentheses) by depth strata at Green Canyon 18 from 

October 4 - 5, 1994 from visual point count surveys . 

Depth m 

0 

w 

Species 0 - 20 20 - 40 40 - 60 60 - 80 80-100 100 - 120 120 - 140 140 - 160 160 - 180 0 - 219 

Almaco Jack 8(3 .2) 3(l .9) 98 (28.3) 60 (33.7) 169 (18.1) 169 (18.1) 

Greater 

Amberjack 

34(9.8) 37 (20.8) 71(7.6) 71 (7 .6) 

Bar Jack 46 (28.4) 5(l .4) 51(5.5) 51 (5 .5) 

Barracuda 11 (4 .4) 15(9.3) 1 (0 .3) 27(2.9) 27(2.9) 

Bermuda 

Chub 

37 (14.9) 1 (0 .3) 38(4.1) 38(4.1) 

Black Jack 1 (0 .3) 1 (0 .1) ](0.1) 

Blackfin 

Tuna 

80 (44.9) 80(8.6) 80(8.6) 

Bluerunner 154 (61 .8) 154 (16.5) 154 (16.5) 

Creolefish 37 (14.9) 58 (35.8) 201 (58.1) 296 (31 .7) 296 (31 .7) 

Gray 

Triggerfish 

1 (0 .4) 1 (0 .6) 4(l .2) 1 (0 .6) 7(0.7) 7(0.7) 

Horseye Jack 1 (0 .4) 36 (22.2) 37(4.0) 37(4.0) 

Lesser 

Amberjack 

Ocean 

Triggerfish 

Rainbow 

Runner 

3(l.9) 3(0.3) 3(0.3) 

Scamp 1 (0.3) 1(0.1) ~ (0 .1) 

*Note: If cell is empty, no individuals were observed of that species for that depth interval . 
Table 11 b. Number enumerated and percent species composition (in parentheses) by depth strata at Green Canyon 18 from 

November 30 - December 1, 1994 from visual point count surveys . 

Death fml 

0 

Species 0 - 20 20 - 40 40 - 60 60 - 80 80 - 100 100 - 120 120 - 140 140 - 160 160 - 180 0 - 219 

Almaco 

Jack 

10(3 .6) 9(11 .7) 1 (2 .1) 20(2.8) 

Greater 

Amberjack 

12(4 .3) 31 (40.3) 44 (93 .6) 87(12.2) 

Bar Jack 4(2.0) 30 (10.9) 34(4.8) 

Barracuda 6(5 .3) 6(3.0) 2(0.7) 14(2 .0) 

Bermuda 

Chub 

20 (17.7) 20(2.g) 

Black Jack 4(2.0) 15(5 .4) 19(2 .7) 

Blackfin 

Tuna 

Bluerunner 

Creolefish 79 (69.9) 159 (80.3) 187 (67.8) 29 (37.7) 454 (63.9) 

Gray 

Triggerfish 

2(l .0) 10(3 .6) 12(l .7) 

Horseye 

Jack 

4(3 .5) 19(9 .6) 10(3 .6) 33(4.6) 

Lesser 

Amberjack 

Rainbow 

Runner 

Scamp 8(10.4) 2(4.3) 10( 1 .4) 

Yellowtail 

Snapper 

4(3.5) 4(2.0) 8(l .1) 
Table 11 c. Number enumerated and percent species composition (in parentheses) by depth strata at Green Canyon 18 from 

January 20 - 21, 1995 from visual point count surveys . 

Depth m 

0 

Species 0- 20 20 - 40 40 - 60 60 - 80 80 - 100 100 - 120 120 - 140 140 - 160 160 - 180 0 - 219 

Almaco Jack 4(0.8) 2(l .1) 60 (35.5) 24 (14.2) 90(5.7) 

Greater 

Amberjack 

1(0.5) 37 (21 .9) 79 (46.7) 1(100.0) 118 (7 .5) 

Bar Jack 63 (12.8) 29(5 .3) 8(4.7) 100 (6 .4) 

Barracuda 34(6.9) 55 (10.1) 4(2.1) 2(l .2) I (0 .6) 96(6.1) 

Bermuda 

Chub 

137 (27.7) 137 (8 .7) 

Black Jack 5(0.9) 2(l .2) 7(0.4) 

Blackfin 

Tuna 

31 (16.4) 12(7 .1) 37 (21 .9) 80(5.1) 

Bluerunner 73 (13.4) 73(4.7) 

Creolefish 190 (38.5) 280 (51 .4) 132 (69.8) 24 (14.2) 626 (39.9) 

Gray 

Triggerfish 

12(6.3) 6(3 .6) 18(l .1) 

Horseye Jack 49(9.9) 85 (15.6) 134 (8 .6) 

Lesser 

Amberjack 

Rainbow 

Runner 

3(0.6) 3(0.2) 

Scamp 7(3.7) 18 (10.7) 28 (16.6) 53 (3 .4) 

Yellowtail 

Snapper 

14(2 .8) 18(3 .3) 32(2.0) 
Table 11 d. Number enumerated and percent species composition (in parentheses) by depth strata at Green Canyon 18 from 

May 11 - 12, 1995 from visual point count surveys. 

Depth (m) 

0 

o1, 

Species 0 - 20 20 - 40 40 - 60 60 - 80 80 - 100 100 - 120 120 - 140 140 - 160 160 - 180 0 - 219 

Almaco Jack 51 (11 .7) 7(4.1) 10 (17.9) 58(8.1) 

Greaser 

Amberjack 

11 (2 .5) 7(4.1) 5(83 .3) 33(4.6) 

Bar Jack 9(2.1) 9(l .3) 

Barracuda 14 (31 .8) 12(2 .8) 26(3.6) 

Bermuda 

Chub 

Black Jack 3(0.7) 3(0.4) 

Biackfin 

Tuna 

11 (6 .4) 1] (1 .5) 

Bluerunner 

Creolefish 30 (68.2) 317 (72.7) 125 (72.7) 35 (62.5) 507 (71.0) 

Gray 

Triggerfish 

1 (0.2) 8(4.7) 9(l .3) 

Horseye Jack 3(0.7) 7(4.1) 8(14.3) 18(2 .5) 

Lesser 

Amberjack 

Ocean 

Triggerfish 

4(2.3) 4(0.6) 

Scamp I (0.2) 3 (1 .7) 3(5 .4) 1 (16.7) 8(l .1) 

Yellowtail 

Snapper 

28(6.4) 28(3.9) 
Table l l e. Number enumerated and percent species composition (in parentheses) by depth strata at Green Canyon 18 from 

July 11 - 12, 1995 from visual point count surveys. 

Depth (m) 

0 

V 

Species 0 - 20 20 - 40 40 - 60 60 - 80 80 - 100 100 - 120 120-140 140 - 160 160 - 180 0 - 219 

Almaco Jack 23 (24.0) 14 (70.0) 37(3 .8) 

Bar Jack 3(l .4) 6(l .6) 9(0.9) 

Barracuda 6(2.8) 4(1 .1) 2(0.8) 12(l .2) 

Bermuda 

Chub 

48 (22.5) 48(4.9) 

Black Jack 3(0.8) 3(0.3) 

Blackfin 

Tuna 

Bluerunner 59 (27.7) 53 (13.9) 38 (14.3) 150 (15.4) 

Creolefish 83 (39.0) 304 (80.0) 212 (79.7) 57 (59.4) 656 (67.3) 

Gray 

Triggerfish 

2(0.8) 3 (3 .1) 5(0.5) 

Greater 

Amberjack 

4(l .5) 11 (11 .5) 4(20.0) 19(1 .9) 

Horseye Jack 14(6 .6) 6(l .6) 8(3.0) 28(2.9) 

Lesser 

Amberjack 

Ocean 

Triggerfish 

Rainbow 

Runner 

4(1 .1) 4(0.4) 

Scamp 2(2.1) 2(10.0) I 4 (0 .4) 
Table 11 f. Number enumerated and percent species composition (in parentheses) by depth strata at Green Canyon 18 from 

December 1 - 2, 1995 from visual point count surveys . 

Death (m) 

0 

00 

Species 0 - 20 20 - 40 40 - 60 60 - 80 80 - 100 100 - 120 120 - 140 140-160 160-180 0- 219 

Almaco Jack 3(0.9) 79 (23.2) 37 (72.5) 2(100.0) 1(100.0) 2(100.0) 124 (5 .0) 

Bar Jack 25(2.5) 19(2.6) 4(l .2) 2(0.6) 50(2.0) 

Barracuda 24(2.4) 29(3 .9) 5(l .4) 2(0.6) 60(2.4) 

Bermuda 

Chub 

250 (24.9) 250 (10.1) 

Black Jack 2(0.3) 2(0.6) 7(2.1) 11 (0 .4) 

Blackfin 

Tuna 

Bluerunner 240 (23 .9) 82 (11 .2) 24(6.9) 9(2.6) 355 (14.3) 

Creolefish 457 (45 .5) 571(7 7.7) 283 (81 .8) 164 (48.1) 1475 (59.4) 

Gray 

Triggerfish 

4(0.4) 7(l .0) 3(0.9) 22(6.5) 36(l .5) 

Greater 

Amberjack 

2(0.3) 19(5 .5) 21 (6 .2) 9(17.6) 51 (2 .1) 

Horseye Jack 22(3.0) 18(5 .3) 40(l .6) 

Lesser 

Amberjack 

8(2.3) 8(0.3) 

Ocean 

Triggerfish 

Rainbow 

Runner 

4(0.4) 

~ 

4(0.2) 

Scamp 1(0.1) 3(0.9) 9(2.6) 4(7.8) ~ 17(0.7) 
Table 1 l g. Number enumerated and percent species composition (in parentheses) by depth strata at Green Canyon 18 from 

March 4 - 5, 1995 from visual point count surveys. 

Depth (m) 

r 

O 

Species 0- 20 20 - 40 40 - 60 60 - 80 80 - 100 100 - 120 120-140 140 - 160 160 - 180 0 - 219 

Almaco Jack 2(2.6) 40 (59.7) 14 (82.4) 56(3.5) 

Bar Jack 22(3.0) 3(0.5) 25(l .6) 

Barracuda 38(5.1) 7(1.1) 45(2.8) 

Bermuda 

Chub 

137 (18.5) 46(7.5) 183 (> 

Black Jack 

Blackfin 

Tuna 

Bluerunner 291 (39.2) 63 (10.2) 354 (22.0) 

Creolefish 225 (30.3) 445 (72.1) 85 (95.5) 72 (92.3) 13 (19.4) 840 (52.1) 

Gray 

Triggerfish 

5(0.7) 4(0.6) 1 (5 .9) 10(0 .6) 

Greater 

Amberjack 

2(0.3) 3(3.4) 2(2.6) 9(13.4) 2(11 .8) 18 (1 .1) 

Horseye Jack 13(1 .8) 4(0.6) 17(1 .1 ) 

Lesser 

Amberjack 

Ocean 

Triggerfish 

4(0.5) 4(0.2) 

Rainbow 

Runner 

7(0.9) 43(7.0) 50(3 .1) 

Scamp 1 (1 .1) 2(2.6) 5(7.5) 8(0.5) 
Table 11 h. Number enumerated and percent species composition (in parentheses) by depth strata at Green Canyon 18 from 

April 9 -10, 1996 from visual point count surveys . 

Depth (m) 

r 

0 

Species 0 - 20 20 - 40 40 - 60 60 - 80 80 - 100 100 - 120 120 - 140 140 - 160 160 - 180 0 - 219 

Almaco Jack l (O .2) 49 (30.1) 35 (58.3) 5(26.3) 1(100.0) 91 (6 .2) 

Bar Jack 3(0.5) 3(0.2) 

Barracuda 33(5 .3) 13 (2 .1) 2(l .2) 48(3.3) 

Bermuda 

Chub 

74 (12.0) 8(l .3) 6(3.7) 88(6.0) 

Black Jack 3(l .8) 3(0.2) 

Blackfin 

Tuna 

Bluerunner 251 (40.5) 235 (38.5) 486 (33.0) 

Creolefish 220 (35.5) 309 (50.6) 89 (54.6) 15 (25.0) 633 (43.0) 

Gray 

Triggerfish 

1(5.3) 1 (0 .1 

Greater 

Amberj ack 

12(7 .4) 7(11 .7) 12 (63 .2) 31(2.1) 

Horseye Jack 34(5.5) 46(7.5) 80(5.4) 

Lesser 

Amberjack 

Ocean 

Triggerfish 

Rainbow 

Runner 

3 (0 .5) 3(0.2) 

Scamp 2(l .2) 3(5.0) 1 (5 .3) I 6(0.4) 
Table 11 i . Number enumerated and percent species composition (in parentheses) by depth strata at Green Canyon 18 from 

September 11 - 12, 1996 from visual point count surveys . 

Depth (m) 

Species 0- 20 20 - 40 40 - 60 60 - 80 80-100 100 - 120 120 - 140 140 - 160 160 - 180 0- 219 

Almaco Jack 24(3.8) 42 (12.6) 2(10.5) 68(2.9) 

Bar Jack 4(0.6) 7 (1 .1) 11(0 .5) 

Barracuda 25(4.0) 12(l .6) l (O .2) 38(l .6) 

Bermuda 

Chub 

75 (11 .9) 26(3.5) 10](4.3) 

Black Jack 6(0.9) 2(0.6) 8(0.3) 

Bluerunner 191 (30.4) 332 (45.2) 354 (55.8) 877 (37.3) 

Creolefish 313 (49.8) 327 (44.6) 219 (34.5) 194 (58.1) 1053 (44.8) 

Gray 

Triggerfish 

1 (0.1) 3(0.5) 10(3 .0) 14(0 .6) 

Greater 

Amberjack 

10(l .6) 71 (21 .3) 17 (89.5) 98(4.2) 

Horseye Jack 15(2 .4) 36(4.9) 4(0.6) 55(2.3) 

Lesser 

Amberjack 

Marbled 

Grouper 

1 (03) 1 (0 .0) 

Ocean 

Triggerfish 

1 (0 .2) 2(0.3) 3 (0 .1) 

Rainbow 

Runner 

5(0.8) 5(0.2) 

Scamp 4(0.6) 13(3 .9) 17(0 .7) 
Table 11 j . Number enumerated and percent species composition (in parentheses) by depth strata at Green Canyon 18 from 

November 18 - 20, 1996 from visual point count surveys . 

Depth (m) 

N 

Species 0 - 20 20 - 40 40 - 60 60 - 80 80 - 100 100-120 120-140 140 - 160 160 - 180 0 - 219 

Almaco Jack 26 (21 .5) 2(8.7) 28(8.3) 

Bar Jack 1 (0 .8) I (0.3) 

Barracuda 7(5 .3) 8(21 .6) 3(13.0) 5(4.1) 23(6.8) 

Bermuda 

Chub 

25 (18.8) 25(7.4) 

Black Jack 6(5 .0) 2(8.7) 8(2.4) 

Blackfin 

Tuna 

Bluerunner 57 (42.9) 57 (16.9) 

Creolefish 39 (29.3) 26 (703) 19 (82.6) 60 (49.6) 9(39.1) 153 (45.4) 

Gray 

Triggerfish 

1 (0 .8) I (0.3) 

Greater 

Amberjack 

14 (11 .6) 7(30.4) 21 (6 .2) 

Horseye Jack 3(2 .3) 3(8.1) 1 (4 .3) 7(2.1) 

Lesser 

Amberjack 

Ocean 

Triggerfish 

Rainbow 

Runner 

2(1 .5) 2(0.6) 

Scamp 8(6.6) 2(8.7) 10(3 .0) 
Table 11 k. Number enumerated and percent species composition (in parentheses) by depth strata at Green Canyon 18 from 

March 4 - 5, 1997 from visual point count surveys . 

Depth (m) 

w 

Species 0 - 20 20 - 40 40 - 60 60 - 80 80 - 100 100 - 120 120 - 140 140 - 160 160 - 190 0- 219 

Almaco Jack 2(0.5) 2(0.4) 80 (34.2) 14 (66.7) 4(66.7) 102 (6.0) 

Bar Jack 5(0.9) 5(0.3) 

Barracuda 44(7.9) 28(6.4) 8(l .8) 2(0.9) 82(4.8) 

Bermuda 

Chub 

61 (10.9) 61 (3 .6) 

Black Jack 5(1 .1) 5(0.3) 

Blackfin 

Tuna 

Bluerunner 164 (29.3) 74 (17.0) 264 (57.9) 28 (12.0) 530 (30.9) 

Creolefish 214 (38.2) 296 (68.0) 174 (38.2) 79 (33 .8) 763 (44.5) 

Gray 

Triggerfish 

9(3.8) 2(9.5) 11 (0 .6) 

Greater 

Amberjack 

2(0.5) 6(l .3) 33 (14.t) 2(9.5) 2(33 .3) 45(2.6) 

Horseye Jack 69 (12.3) 28(6.4) 97(5.7) 

Lesser 

Amberjack 

Ocean 

Triggerfish 

Rainbow 

Runner 

3 (0 .5) 3(0.2) 

Scamp 2(0.4) 3 (13) 3(14.3) T ~ ~ 8 (0 .5) 
Table 111. Number enumerated and percent species composition (in parentheses) by depth strata from all trips to Green Canyon 18 

from August 1994 - March 1997 from visual point count surveys . 

Death (m) 

Species 0 - 20 20 - 40 40 - 60 60 - 80 80 - 100 100 - 120 120 - 140 140 - 160 160 - 180 0 - 219 

Almaco Jack 13(0.3) 56(l .1) 195 (6 .6) 416 (23.9) 139 (31.7) 21 (67.7) 1 (33 .3) 2(66.6) 843 (5 .7) 

Bar Jack 122 (2 .6) 116 (2 .4) 46(1 .6) 11(0.6) 295 (2 .0) 

Barracuda 242 (5 .1) 189 (3 .9) 28(0.9) 11(0.6) 1 (0 .2) 471 (3 .2) 

Bermuda 

Chub 

864 (18.1) 80(l .6) 7(0.2) 951 (6.4) 

Black Jack 14(0 .3) 27(0.9) 15(0.9) 2(0.5) 58(0.4) 

Blackfin 

Tuna 

42(l .4) 92(5 .3) 37(8.4) 171 (1 .2) 

Bluerunner 1407 (29.4) 912 (t8.7) 680 (23.0) 37(2.1) 3036 (20.5) 

Creolefish 1887 (39.5) 3092 (63.3) 1726 (58.3) 729 (41 .9) 22(5.0) 7456 (50.2) 

Gray 

Triggerfish 

10(0 .2) 16(0.3) 42(1 .4) 52(3 .0) 3(0.7) 1 (3 .4) 124 (0 .8) 

Greater 

Amberjack 

17(0 .3) 108 (3 .6) 274 (15.7) 188 (42.8) 5(17.2) 592 (4 .0) 

Horseye Jack 202 (4.2) 288 (5 .9) 30(1 .0) 26(l .5) 546 (3 .7) 

Lesser 

Amberjack 

8(0.5) 8(0.1) 

Marbled 

Grouper 

1 (0 .1) l(0.0) 

Ocean 

Triggerfish 

5(0.1) 6(0.2) 11(0.1) 
Table 111 (continued) . Number enumerated and percent species composition (in parentheses) by depth strata from all trips to Green Canyon 18 

from August 1994 - March 1997 from visual point count surveys . 

Depth (m) 

Species 0-20 20-40 40-60 60-80 80-100 100-120 120-140 140-160 160-180 0-219 

Rainbow 

Runner 

13(0.3) 50(1.0) 63(0.4) 

Scamp 2(0.0) 23(0.8) 67(3.9) 46 (10.5) 138 (0 .9) 

Unidentified 

Grouper 

1(0.2) 2(6.9) 1(50 .0) 1 (33 .3) 1 (100 .0) 6(0.0) 

Yellowtail 

Snapper 

18(0.4) 50(1.0) 68(0.5) 

rr 

rr 
Table 12a . Estimated number of fish by species (with 95% confidence intervals) by depth strata at Green Canyon 18 from 

October 4 -5, 1994 from hydroacoustic and visual point count surveys . 

Depth m 

Species 0 - 20 20 - 40 40 - 60 60 - 80 80 - 100 100 - 120 120 - 140 140 - 160 160 - 180 0 - 219 

Almaco 

Jack 

465.1 (44.4) 7.5 (5 .2) 3 .9(l .8) 476.5 (51 .4) 

Bar Jack 111 .7 (77.5) 0.2 (0.1) 

1119 (77.6) 

Barracuda 639.5 (61 .1) 36.6 (25.4) 6761 (86.5) 

Bermuda 

Chub 

2165S (206 .9) 2165 .5 (206 .9) 

Black Jack 

Blackfin 

Tuna 

Bluerunner 89819 (858 .0) 89819 (858) 

Creolefish 2165.5 (206 .9) 140.8 (97.7) 8.1 (3 .8) 2314 .4 (308 .4) 

Gray 

Triggerfish 

58 .1 (5 .6) 2.4(l .6) 0.2 (0.1) 611.7 (7 .3) 

Greater 

Amberjack 

1 .4 (0.6) 1 .4(.6) 

Horseye 

Jack 

58 .1 (5 .6) 87.3 (60.6) 145.4 (66.2) 

Rainbow 

Runner 

7.5 (5 .2) 7.5 (5 .2) 

Scamp 

Yellowtail 

Snapper 

TOTAL (1668 149413 .1) *Note: If cell is empty, no individuals were observed of that species for that depth interval . 
Table 12b. Estimated number of fish by species (with 95% confidence intervals) by depth strata at Green Canyon 18 from 

November 30 - December l, 1994 from hydroacoustic and visual point count surveys . 

Depth m) 

v 

Species 0 - 20 20 - 40 40 - 60 60 - 80 80 - 100 100 - 120 120 - 140 140 - 160 160-180 0 - 219 

Almaco Jack 74 .3 (30.9) 118.3 (28.8) 8.4 (2 .5) 506A (201) 

Bar Jack 24.4 (13.4) 225.0 (93 .4) 249.4 (106 .8) 

Barracuda 6569 (138 .0) 36.6 (20.0) 14 .4 (60.0) 707.9 (218) 

Bermuda 

Chub 

2193 .8 

(460 .8) 

2193 .8 

(460 .8) 

Black Jack 24.4 (13.4) 111.4 (46.3) 135.8 (59.7) 

Blackfin 

Tuna 

Bluerunner 

Creolefish 8663 .7 

(1819.8) 

980.1 (536 .3) 1399.3 

(581 .0) 

381 .2 (93.0) 11424.3 

(3030.1) 

Gray 

Triggerfish 

12 .2 (6 .7) 743 (30.9) 86 .5 (37.6) 

Greater 

Amberjack 

88 .7 (36.9) 407.5 (99.3) 375.4 (112 .2) 471 .6 (248 .4) 

Horseye Jack 433.8 (91.1) 117.2 (64.1) 74 .3 (30.9) 625 .3 (186.1) 

Rainbow 

Runner 

Scamp 105.2 (25.6) 17 .2 (5 .2) 122.4 (30.8) 

Yellowtail 

Snapper 

396.7 (91,1) 24.4 (13 .4) 421 .1 (104 .5) 

TOTAL 16944.1 

(4683.8) 
Table 12c . Estimated number of fish by species (with 95% confidence intervals) by depth strata at Green Canyon 18 from 

January 20 - 21, 1995 from hydroacoustic and visual point count surveys . 

Depth (m) 

00 

Species 0 - 20 20 - 40 40 - 60 60 - 80 80 - 100 100 - 120 120 - 140 140 - 160 160 - 180 0 - 219 

Almaco Jack 39.6 (5 .8) 21S (4 .9) 8729 (162 .6) 135.7 (49.6) 1069 .7 

(222 .9) 

Bar Jack 617.0 (93 .5) 76 .6 (23.4) 115.6 (21 .5) 809.2 (138 .4) 

Barracuda 332 .6 (50.4) 146.0 (44.7) 41 .1 (9.4) 29.5 (5 .5) 5.7 (2 .1) 5549 (112 .1) 

Bermuda 

Chub 

1335 .3 

(202 .4) 

1335 .3(202 .4 

) 

Black Jack 13A (4 .0) 29.5 (5 .5) 42 .5 (9 .5) 

Blackfin 

Tuna 

321 .2 (73.2) 174,6 (32.5) 209.3 (76.5) 705.1 (182 .2) 

Bluerunner 193.7 (59.3) 193.7 (59.3) 

Geolefish 1856.0 

(2813) 

143 .0 (227 .3) 1367 .1 

(311 .7) 

349.2 (65.0) 3715.3 

(885 .3) 

Gray 

Triggerfish 

123.4 (28.1) 88 .5 (16.5) 2119 (44.6) 

Greater 

Amberjack 

9.8 (2 .2) 538.5 (100 .3) 446.2 (163 .2) 1348 .0 

(352 .3) 

2342 .5 (618) 

Horseye Jack 477.2 (72.3) 225.5 (67.0) 702.7 (139 .3) 

Rainbow 

Runner 

289 (4 .4) 289 (4 .4) 

Scamp 72S (16.5) 263.1 (49.0) 158.6 (58.0) 494.2 (123 .5) 

Yellowtail 

Snapper 

135.0 (20.5) 47.7 (15.0) 182.7 (35.5) 

TOTAL 1 2388.6 

(2777.4) 
Table 12d . Estimated number of fish by species (with 95% confidence intervals) by depth strata at Green Canyon 18 from 

July 11 - 12, 1995 from hydroacoustic and visual point count surveys . 

Depth (m) 

Species 0 - 20 20 - 40 40 - 60 60 - 80 80 - 100 100 - 120 120-140 140 - 160 160-180 0 - 219 

Almaco Jack 53 .3 (23.8) 255.4 (202 .3) 308.7 (226 .1) 

Bar Jack 161 .7 (16.2) 149 (6 .9) 176.6 (23.1) 

Barracuda 323.3 (32.4) 10 .2 (4 .7) 0.8 (0 .4) 334.3 (37.5) 

Bermuda 

Chub 

2598.0 

(260 .6) 

2598 (260 .6) 

Black Jack 7.4 (3 .4) 7.4 (3 .4) 

Blackfin 

Tuna 

Bluerunner 3198.4 

(320 .8) 

129.4 (59.9) 15 .1 (7 .1) 3342 .9 

(387 .8) 

Creolefish 4503 .2 

(451 .7) 

7449 (344 .6) 84 .4 (39.6) 132.0 (59.0) 5464 .5 

(894 .9) 

Gray 

Triggerfish 

0.8 (0 .4) 6.9(3 .1) 7.7 (3 .5) 

Greater 

Amberjack 

1 .6 (0 .7) 25.6 (11 .4) 73A (57.8) 100.2 (69.9) 

Horseye Jack 762.1 (76.4) 149 (6 .9) 3.2(l .5) 780.2 (84.8) 

Rainbow 

Runner 

10 .2 (4 .7) 10 .2 (4 .7) 

Scamp 4.7 (2 .1) 36 .5 (28.9) 41 .2 (31) 

Yellowtail 

Snapper 

TOTAL 13171 .9 

(2027.3) 
Table 12e. Estimated number of fish by species (with 95% confidence intervals) by depth strata at Green Canyon 18 from 

December 1 - 2, 1995 from hydroacoustic and visual point count surveys . 

Death (m) 

N 

O 

Species 0 - 20 20 - 40 40 - 60 60 - 80 80 - 100 100 - 120 120-140 140 - 160 160 - 180 0- 219 

Almaco Jack 13 .6 (4 .1) 220.0 (32.9) 619.2 (280 .1) 354.7 (75.9) 394.4 (112 .7) 16.7 (5 .2) 1618.6 

(510 .9) 

Bar Jack 1109 (17.3) 28 .6 (10.0) 18 .1 (5 .5) 5 .7 (0.9) 163.3 (33.7) 

Barracuda 106.4 (16.6) 429 (15 .0) 21 .1 (6 .4) 5 .7 (0.9) 176.1 (38.9) 

Bermuda 

Chub 

1104.4 

(172 .6) 

1104.4 

(172 .6) 

Black Jack 3.3 (1 .2) 9.0(2 .8) 199 (3 .0) 32 .2(7) 

Blackfin 

Tuna 

Bluerunner 1060.0 

(165 .6) 

123 .1 (43.1) 103.9 (31 .8) 24 .7 (3 .7) 1311 .7 

(244 .2) 

Geolefish 2018.0 

(315 .3) 

854.1 (299.1) 1231 .8 

(376.8) 

456.0 (68.3) 4559.9 

(1059.5) 

Gray 

Triggerfish 

17 .7 (2 .8) 11A (3 .9) 13 .6 (4 .1) 61,6 (9 .2) 1039 (20) 

Greater 

Amberjack 

3 .3 (1 .2) 82.8 (25.3) 58 .8 (8 .8) 150.3 (68.0) 295.2 (103 .3) 

Horseye Jack 33A (11 .6) 50.2 (7 .5) 83 .2 (19.1) 

Lesser 

Amberjack 

21 .8 (3 .3) 21 .8 (3 .3) 

Rainbow 

Runner 

17 .7 (27.8) 17 .7 (27.8) 

Scamp 1 .1 (0 .4) 13 .6 (4 .1) 24.6 (3 .7) 666.2 (30.1) 7055 (38.3) 

Yellowtail 

Snapper 

TOTAL 10193.5 

(2278.6) 
Table 12f. Estimated number of fish by species (with 95% confidence intervals) by depth strata at Green Canyon 18 from 

March 4 - 5, 1996 from hydroacoustic and visual point count surveys . 

Depth m) 

N 

Species 0 - 20 20 - 40 40 - 60 60 - 80 80 - 100 100 - 120 120 - 140 140 - 160 160 - 180 0 - 219 

Almaco Jack 88 .7 (15.9) 949.7 (319.7) 1344 .9 

(355 .4) 

2383 .3 (691) 

Bar Jack 138.4 (22.7) 8.0(2 .6) 146.4 (25.3) 

Barracuda 235 .2 (38.7) 17 .6 (5 .6) 252.8 (44.3) 

Bermuda 

Chub 

835.5 (140 .2) 119.7 (38.5) 955.2 (178 .7) 

Black Jack 

Blackfin 

Tuna 

Bluerunner 1808 .5 

(297 .1) 

162.8 (52.3) 1971 .3 

(349 .4) 

Creolefish 1397 .9 

(229 .7) 

1150.9 

(369 .7) 

2027 .1 

(431 .6) 

3149 .6 

(118 .9) 

308.6 (103 .9) 8034 .1 

(1253 .8) 

Gray 

Triggerfish 

32.3 (5 .3) 9.6 (3 .1) %.3(25 .4) 138.2 (33.8) 

Greater 

Amberjack 

4.8(l .5) 72.2 (15.4) 88.7 (15.9) 213.2 (71 .8) 192.6 (50.9) 571 .5 (155 .5) 

Horseye Jack 83 .0 (13.6) 9.6 (3 .1) 92 .6 (16.7) 

Ocean 

Triggerfish 

23.1 (3 .8) 23 .1 (3 .8) 

Rainbow 

Runner 

41S (6.8) 111 .7 (35.9) 153 .2 (42.7) 

Scamp 23 .3 (5 .0) 88.7 (15 .9) 119.3 (40.2) 231 .3 (61 .1) 

Unidentified 

Grouper 

43 .9 (10.0) 439 (10) 

TOTAL 14996 

(2866.1) 
Table 129. Estimated number of fish by species (with 95% confidence intervals) by depth strata at Green Canyon 18 from 

April 9 -10, 1996 from hydroacoustic and visual point count surveys . 

Depth m 

N 

N 

Species 0 - 20 20 - 40 40 - 60 60 - 80 80 - 100 100 - 120 120 - 140 140 - 160 160-180 0 - 219 

Almaco Jack 1 .4(0 .4) 580.1 (215 .1) 6839 (234 .4) 308.4 (172 .1) 1339 .5 

(699 .4) 

2913.3 

(1321 .4) 

Bar Jack 3.5(l .0) 3.5(l) 

Barracuda 37 .5 (10.6) 42A (16.8) 23 .1 (8 .6) 102 .6 (36) 

Bermuda 

Chub 

85 .0 (24.1) 26A (10.4) 7t .3 (26.4) 182.3 (60.9) 

Black Jack 34.7 (12.9) 34 .7 (12.9) 

Blackfin 

Tuna 

Bluerunner 286.9 (81.3) 769.7 (307 .1) 1056 .6 

(388 .4) 

Creolefish 251 .5 (71.3) 1011 .6 

(403 .6) 

1052 .4 

(390.2) 

293.3 (100 .5) 2608.8 

(965 .6) 

Gray 

Triggerfish 

62.1 (34.7) 62.1 (34.7) 

Greater 

Amberjack 

142.6 (52.9) 137.3 (47.0) 741 .0 (413 .6) 1020 .9 

(513 .5) 

Horseye Jack 39 .0 (I 1 .0) 1499 (59.8) 1889 (70.8) 

Rainbow 

Runner 

3 .5(l .0) 3.5(l) 

Scamp 23 .1 (8 .6) 58.7 (20.1) 62.1 (34.7) 1439 (63.4) 

Yellowtail 

Snapper 

TOTAL 8321 .1 

(3469.6) 
Table 12h. Estimated number of fish by species (with 95% confidence intervals) by depth strata at Green Canyon 18 from September 11 - 12, 1996 

from hydroacoustic and visual point count surveys . 

Death (m) 

N 

W 

Species 0 - 20 20 - 40 40 - 60 60 - 80 80 - 100 100-120 120 - 140 140 - 160 160 - 180 0 - 219 

Almaco Jack 24 .8 (7 .5) 49.1 (15 .3) 45 .8 (35.4) 119.7 (58.2) 

Bar Jack 52 .8 (7.8) 7.2 (2 .2) 60(10) 

Barracuda 351 .7 (52.2) 44 .3 (14.9) 1 .3 (0 .4) 397.3 (67.5) 

Bermuda 

Chub 

1046 .4 

(155 .2) 

97 .0 (32.5) 1143 .4 

(1g~~7) 

Black Jack 5.9(l .8) 2.3 (0 .7) 8.2(2 .5) 

Bluerunner 2673 .1 

(396 .6) 

1252 .3 

(419.6) 

363.6 (110 .7) 4289 (926 .9) 

Creolefish 4379.0 

(649 .6) 

1235 .6 

(414.0) 

224.8 (68.4) 226.2 (70.4) 6065 .6 

(1202.4) 

Gray 

Triggerfish 

2.8 (0 .9) 3.3(l .0) 11 .7 (3 .6) 17 .8 (5 .5) 

Greater 

Amberjack 

10.4 (3 .2) 82.9 (25.8) 390.0 (301 .4) 483.3 (330 .4) 

Horseye Jack 211 .0 (31 .3) 135 .8 (45 .5) 3.9(l .2) 350.7 (78) 

Marbled 

Grouper 

1 .2 (0.4) 1 .2 (.4) 

Ocean 

Triggerfish 

17 .6 (2 .6) 2.0 (0 .6) 19 .6 (3 .2) 

Rainbow 

Runner 

70 .3 (10.4) 70.3 (10.4) 

Scamp 3.9(l .2) 15 .2 (4 .7) 19 .1 (5 .9) 

TOTAL 13045 .2 

(2889) 
Table 12i . Estimated number of fish by species (with 95% confidence intervals) by depth strata at Green Canyon 18 from 

November 18 - 20, 1996 from hydroacoustic and visual point count surveys . 

Depth (m) 

N 

41 

Species 0 - 20 20 - 40 40 - 60 60 - 80 80 - 100 100 - 120 120 - 140 140 - 160 160 - 180 0 - 219 

Almaco Jack 2013 (30.2) 74.3 (33.6) 275.6 (63.8) 

Bar Jack 7.5(l .1) 7.5(l .1) 

Barracuda 228.6 (37.3) 240.4 (83.1) 192.5 (59.9) 38 .4 (5 .8) 6999 (186.1) 

Bermuda 

Chub 

811 .0 (132 .5) 811 (132 .5) 

Black Jack 46.8 (7 .0) 74 .3 (33.6) 121 .1 (40.6) 

Blackfin 

Tuna 

Bluerunner 1850 .6 

(302 .3) 

1850 .6 

(302 .3) 

Creolefish 1263 .9 

(206 .5) 

782.3 (270 .6) 1223 .1 

(382 .2) 

464.4 (69.9) 3339 (151 .0) 4067.6 

(1080.2) 

Gray 

Triggerfish 

7.5 (1 .1) 7.5(l .1) 

Greater 

Amberjack 

108.6 (16.3) 259.6 (117 .4) 368.2 (133 .7) 

Horseye Jack 99 .2 (16.2) 90 .1 (31 .2) 63 .7 (19.8) 253 (67.2) 

Rainbow 

Runner 

64 .7 (10.6) 64 .7 (10.6) 

Scamp 61 .8 (9 .3) 74 .3 (33.6) 136.1 (42.9) 

Unidentified 

Grouper 

36 .7 (16.6) 36.7 (16.6) 

Yellowtail 

Snapper 

TOTAL 8699 .5 

(2078.7) 
Table 12j . Estimated number of fish by species (with 95% confidence intervals) by depth strata at Green Canyon 18 from 

March 4 - 5, 1997 from hydroacoustic and visual point count surveys . 

Depth (m) 

N 

Species 0 - 20 20 - 40 40 - 60 60 - 80 80 - 100 100 - 120 120 - 140 140 - 160 160 - 180 0 - 219 

Almaco Jack 11 .7 (3 .9) 8.3(l .7) 1842 .8 

(309 .4) 

1573 .9 

(511 .7) 

2693.7 

(597 .7) 

6130.4 

(1424.4) 

Bar Jack 47.5 (7 .8) 47.5 (7.8) 

Barracuda 416.6 (68.3) 149.8 (49.5) 37 .5 (7 .4) 48.5 (8 .1) 652.4 (133 .3) 

Bermuda 

Chub 

574.7 (94.2) 574.7 (94.2) 

Black Jack 25 .7 (8 .5) 25 .7 (8 .5) 

Blackfin 

Tuna 

Bluerunner 1544 .9 

(253 .3) 

397.8 (131,4) 1205 .2 

(239 .5) 

646.7 (108 .6) 3794 .6 

(732 .8) 

Creolefish 2014.2 

(330 .2) 

1591 .2 

(525 .8) 

795.2 (158 .0) 18213 

(305 .8) 

6221 .9 

(1319.8) 

Gray 

Triggerfish 

204.18 (34.4) 224.2 (72.9) 428.3 (107 .3) 

Greater 

Amberjack 

11 .7 (3 .9) 27 .1 (5 .4) 759.8 (127 .6) 224.2 (72.9) 1344 .9 

(298 .4) 

2367.7 

(508 .2) 

Horseye Jack 648.6 (106 .3) 149.8 (49.5) 798.4 (155 .8) 

Ocean 

Triggerfish 

Rainbow 

Runner 

26A (4 .3) 45 .0 (9.7) 

Scamp 8.3(l .7) 70A (11 .8) 337.4 (109 .7) 26.4 (4.3) 

Unidentified 

Grouper 

4.4 (3 .0) 649.7 (146 .0) 654.1 (149) 

TOTAL 21767.1 

(4655.1) 
Table 12k. Estimated number of fish by species (with 95% confidence intervals) by depth strata from all trips to Green Canyon 18 

from August 1994 - March 1997 from hydroacoustic and visual point count surveys . 

Depth (m) 

N 

Q1, 

Species 0 - 20 20 - 40 40 - 60 60 - 80 80 - 100 100 - 120 120 - 140 140-160 160 - 180 0 - 219 

Almaco Jack 18 .7 (1 .1) 17A (2 .3) 88 .4 (10.3) 421 (42.1) 326.6 (56.4) 1213 .6 

(148 .2) 

114.7 (17.2) 60.6 (37.5) 2260.6 

(315.1) 

Bar Jack 162.2 (9 .1) 37.2 (5 .1) 21 .4 (2 .5) 10 .3(l .1) 231.1 (17.8) 

Barracuda 318.1 (17.9) 60.4 (8 .2) 12 .1 (1 .4) 10 .3 (1 .1) 2.1 (0 .4) 403.0 (29.0) 

Bermuda 

Chub 

1128 .8 (63.4) 24 .8 (3 .4) 2.7 (0.3) 1156 .3 (67.1) 

Black Jack 4.6 (0 .6) 12 .1 (1 .4) 15 .5(l .6) 5.2 (0 .9) 37 .4 (4 .5) 

Blackfin 

Tuna 

18 .8 (2 .2) 91 .0(9 .3) 86 .6 (15.0) 196.4 (26.5) 

Bluerunner 1833 .6 

(102 .9) 

289.6 (39.5) 308.2 (35.9) 36 .1 (3 .7) 2462.3 

(182 .0) 

Creolefish 2463 .4 

(138 .3) 

908.4 (133 .6) 781 .2 (90.9) 719.7 (73 .7) 51 .5 (8 .9) 4924.2 

(445 .4) 

Gray 

Triggerfish 

12S (0.7) 4.6 (0.6) 18 .8 (2 .2) 51 .5 (5 .3) 7.2(l .2) 57 .4 (7 .0) 152(17) 

Greater 

Amberj ack 

4.6 (0.6) 48.2 (5 .6) 269.7 (27.6) 441 .0 (76.2) 288.6 (35 .2) 1052.1 

(145 .2) 

Horseye Jack 2619 (14.7) 91 .4 (12.4) 13 .4(l .6) 25 .8 (2 .6) 392.5 (31 .3) 

Lesser 

Amberjack 

8.6 (0 .9) 8.6(.9) 

Marbled 

Grouper 

l.? (0 .2) 1 .7 (.2) 

Ocean 

Triggerfish 

6.2 (0 .4) 6(0.3) 12 .2(.7) 

Rainbow 

Runner 

8 .7(1 .1) 15S (0 .2) 24 .2(l .3) 

Scamp 10 .7(l .2) 67.0 (6 .9) 108.2 (18.7) 18 59 (26.8) 
Table 12k (continued) . Estimated number of fish by species (with 95% confidence intervals) by depth strata from all trips to Green Canyon 18 

from August 1994 - March 1997 from hydroacoustic and visual point count surveys . 

Depth (m) 

Species 0-20 20-40 40-60 60-80 80-100 100-120 120-140 140-160 160-180 0-219 

Unidentified 6.2(l .1) 29 .5 (2 .0) 29.3 (3 .4) 6.6 (3 .5) 6.7 (3 .1) 78 .3 (13.1) 

Grouper 

Yellowtail 249 (1 .4) 15 .5 (0 .2) 40.4(l .6) 

Snapper 

TOTAL 13855.5 

(1324.1) 

N 

V 
Table 13 . RBD ANOVA (block on platform side) results of vertical target 

strength (dB) with platform side, year, season, time of day, depth, current 

vectors, temperature, salinity, dissolved oxygen and selected interactions 

at the ST54 petroleum platform . 

Source DF SS MS F Prob > F 

Model 206 56386.345015 273 .720121 34.40 0.0001 

Error 1198 9532.903189 7.957348 

Corrected Total 1404 65919.248205 

R-Square C.V. Root MSE WANTS 

Mean 

0.855385 -7.065331 2.8208772 -39.925621 

Variables DF Type III SS Mean Square F Value Pr > F 

Side 3 6671 .413209 2223 .804403 279.47 0.0001 

Year 1 40.001821 40.001821 5 .03 0.0251 

Season 2 603 .144775 301 .572388 37 .90 0.0001 

Diel 3 367.667924 122.555975 15 .40 0 .0001 

Depth 4 2717.156715 679.289179 85 .37 0.0001 

Temperature 1 136.785653 136 .785653 17.19 0 .0001 

Dissolved 

oxygen 

1 14.260933 14.260933 1 .79 0.1809 

Salinity 1 26.135930 26.135930 3 .28 0.0702 

North vector 1 386.735952 386.735952 48.60 0.0001 

East vector 1 70.694892 70.694892 8 .88 0.0029 

North squared 

vector 

1 203 .938224 203 .938224 25.63 0.0001 

East squared 

vector 

1 352.882525 352.882525 44.35 0.0001 

North * East 1 14.301287 14 .301287 1 .80 0.1803 

Season * Diel 6 841 .199710 140.199952 17.62 0.0001 

Diel* Depth 12 1487.257674 123 .938140 15 .58 0.0001 

Season * Tenth 7 2822.349465 403 .192781 50.67 0.0001 

128 
Table 14. Mean target strengths (dB), with Tukey's studentized means test results 

by season at South Timbalier 54 . 

Season 

Mean 

Target Strength Tukey's Means Test 

Summer -36.9 A 

Spring -39.5 B 

Winter -44 .8 C 

Fall -46.4 

Table 15 . Mean target strengths (dB) with Tukey's studentized means test results 

by time of day at South Timbalier 54 . 

Time of Day 

Mean 

Target Strength Tukey's Means Test 

Dawn -39.9 A 

Noon -40 .1 A 

Midnight -42 .1 B 

Dusk -42 .2 

129 
Table 16. Mean target strengths (dB) with Tukey's studentized means test result 

by platform side at South Timbalier 54. 

Platform Side 

Mean 

Target Strength Tukey's Means Test 

South -38.5 A 

East -40.9 

North -41 .6 C 

West -43 .2 

Table 17 . Mean target strength (dB) with Tukey's studentized means test 

by water depth (m) at South Timbalier 54. 

Depth (m) 

Mean 

Target Strength Tukey's Means Test 

5-10 -39.7 A 

15-20 -39 .8 A 

0-5 -40 .2 A 

10-15 -42 .3 

20-22 -46.2 C 

130 
Table 18 . RBD ANOVA (block on platform side) results of vertical target strength (dB) with 

platform side, year, season, time of day, depth, current vectors, temperature, salinity, 

dissolved oxygen and selected interactions at the GI94 petroleum platform . 

Source DF SS MS F Prob > F 

Model 670 156624.55 233 .77 19 .54 0.0001 

Error 6954 83185 .95 11 .96 

Corrected Total 7624 239810 .49 

R-Square C. V. Root MSE MEANTS 

Mean 

0.653118 -7 .857822 3.4587 -37 .015 

Variables DF Type III SS Mean Square F Value Pr > F 

Side 3 7030.663 2343 .554 195 .91 0.0001 

Year 3 15542 .064 5180.688 433 .08 0.0001 

Season 3 24760.063 8253.354 689.95 0.0001 

Diel 3 385 .026 128 .342 10.73 0.0001 

Depth 11 5357.266 487.024 40.71 0.0001 

Temperature 1 6116 .911 6116 .911 511 .35 0.0001 

Dissolved 

oxygen 

1 2419 .286 2419 .286 202.24 0 .0001 

Salinity 1 49.542 49 .542 4.14 0 .0419 

North vector 1 377.012 377.012 31 .52 0.0001 

East vector 1 7.174 7.174 0.60 0.4387 

North squared 

vector 

1 491 .833 491 .833 41 .12 0.0001 

East squared 

vector 

1 959.615 959.615 80.22 0.0001 

North * East 1 453 .694 453 .694 37.93 0.0001 

Season * Diel 9 801 .514 89.057 7.44 0.0001 

Diel * Depth 33 2909 .926 88.180 7.37 0.0001 

Season * Depth 31 6949 .762 224.186 18 .74 0.0001 

131 
Table 19 . Mean target strength (dB) with Tukey's studentized means test 

by year at Grand Isle 94. 

Year 

Mean 

Target Strength Tukey s Means Test 

1995 -34 .7 A 

1994 -36.4 B 

II 1996 -36.9 B 

1997 -39 .4 C 

Table 20 . Mean target strength (dB) with Tukey's studentized means test 

by season at Grand Isle 94. 

Season 

Mean 

Target Strength Tukey's Means Test 

Winter -32 .4 A 

Spring -34.7 B 

Summer -36.5 C 

Fall -38.6 

132 
Table 21 . Mean target strength (dB) with Tukey's studentized means test 

by time of day at Grand Isle 94 . 

Time of Day 

Mean 

Target Strength Tukey's Means Test 

Midnight -35 .7 A 

Dusk -36.0 B 

Noon -36.1 B 

Dawn -36.3 B 

Table 22 . Mean target strength (dB) with Tukey's studentized means test 

by platform side at Grand Isle 94. 

Platform Side 

Mean 

Target Strength Tukey's Means Test 

South -34.3 A 

West -35.3 

North -36 .7 C 

East -37 .6 

133 
Table 23. Mean target strength (dB) with Tukey's studentized means test 

by water depth (m) at Grand Isle 94 . 

Depth 

(m) 

Mean 

Target Strength Tukey's Means Test 

50-55 -34.1 A 

40-45 -34 .6 A B 

55-60 -34 .9 B 

0-5 -35 .0 B 

45-50 -35 .2 B 

5-10 -35 .3 B C 

10-15 -36.0 C D 

35-40 -36.3 D E 

30-35 -36.9 E F 

25-30 -37.2 

15-20 -38 .0 G 

20-25 -38 .4 G 

134 
Table 24. RBD ANOVA (block on platform side) results of vertical target strength (dB) 

with platform side, year, season, time of day, depth, current vectors, temperature, salinity, 

dissolved oxygen and selected interactions at the GC 18 petroleum platform. 

Source DF SS MS F Prob > F 

Model 314 28349.978141 90.286555 12.56 0.0001 

Error 3050 21933 .357355 7 .191265 

Corrected Total 3364 50283.335496 

R-Square C.V. Root MSE MEANfS 

Mean 

0.563805 -5 .393938 2.6816534 -35 .716060 

Variables DF Type III SS Mean Square F Value Pr > F 

Side 3 7498.586156 2499.528719 347 .58 0.0001 

Year 3 13 .604398 4 .534799 0 .63 0.5952 

Season 3 46.340784 15.446928 2 .15 0.0921 

Diel 3 1059.419025 353 .139675 49.11 0 .0001 

Depth 4 5300.963064 1325 .240766 184.28 0 .0001 

Temperature 1 0.105401 0.105401 0.01 0.9036 

Dissolved 

oxygen 

1 0.000581 0.000581 0.00 0.9928 

Salinity 1 0.464315 0.464315 0.06 0.7994 

North vector 1 69.697543 69.697543 9 .69 0.0019 

East vector 1 14.455526 14.455526 2 .01 0.1564 

North squared 

vector 

1 45.138318 45.138318 6.28 0.0123 

East squared 

vector 

1 0.069053 0.069053 0.01 0.9219 

North * East 1 2.222840 2.222840 0.31 0.5783 

Season * Diel 9 20 .728956 2.303217 0.32 0.9687 

Diel * Depth 12 531 .820136 44.318345 6 .16 0.0001 

Season * Depth 12 92.638315 7.719860 1 .07 0.3781 

135 
Table 25. Mean target strength (dB) with Tukey's studentized means test 

by time of day at Green Canyon 18 . 

Time of Day 

Mean 

Target Strength Tukey's Means Test 

Dawn -37.0 A 

Dusk -37.5 B 

Noon -37.8 B 

Midnight -38.5 C 

Table 26. Mean target strength (d$) with Tukey's studentized means test 

by platform side at Green Canyon 18. 

Platform Side 

Mean 

Target Strength Tukey's Means Test 

South -35.5 A 

West -37.2 B 

East -39 .2 C 

North -39.4 C 

Table 27 . Mean target strength (dB) with Tuicey's studentized means test 

by water depth (m) at Green Canyon 18. 

Depth 

(m) 

Mean 

Target Strength Tukey's Means Test 

0-15 -35 .5 A 

55-75 -37.0 B 

15-35 -37.7 C 

75-95 -38.3 D 

35-55 -39.9 E 

136 
ALA 

T 

LOUISIANA MS 

7 FLORIDA 

TEXAS 

a 

ST5GI94 

G C 18* 

Figure 1 . Position of the three study sites South Timbalier 54 (ST54), Grand Isle 94 (GI94) and Green 

Canyon 18 (GC18) off the Louisiana coast. 

137 
Figure 2. Schematic view of stationary hydroacoustic transducer deployment to measure in situ 

target strength and density of fishes throughout the water column on each side of the platform f 

the three study sites. 

138 
Figure 3. Schematic view of stationary hydroacoustic transducer deployment to measure horiz( 

relative density of fishes associated with petroleum platforms . 

139 
M 

F~ 1 

I~ 0.8 err 

p 0.6 

`r 

0.4 

D 

A 0 .2 

w o 

Year 

Figure 4 . Mean fish density (number of fish/m) by year at Green Canyon 18 (GC 18) and Grand 

Isle 94 (GI94) from July 1994 to March 1997 and South Timbalier (ST54) from August 1995 to 

February 1997 . 

140 

1994 1995 1996 1997 
t~1 

0.8 

~ 0.6 

C 

rte, 0.4 

H 

fl 

A 0 .2 

. . . o 

w 

Season 

Figure 5 . Mean fish density (number of fish / m') by season at Green Canyon 18 (GC 18) and Grand 

Isle 94 (GI94) from July 1994 to March 1997 and South Timbalier 54 (ST54) from August 1995 to 

February 1997. 

141 

Fall Spring Summer Winter 
r. 

8 

0.6 

6) 

0.5 

0.4 

~, 0.3 

. .. 

VJ 

0 0.2 

A 0 .1 

y 

., .., 

w o 

Time of Day 

Figure 6 . Mean fish density (number of fish / m ') by time of day from Green Canyon 18 (GC 18) and 

Grand isle 94 (Gi94) from July 1994 to March 1997 and South Timbalier 54 (ST54) from August 1995 to 

February 1997 . 

142 

Dawn Noon Dusk Midnight 
M 

0.7 

0.6 

o.s 

0.4 A 

~, 0.3 

. . . 

0.2 

A 0 .1 

. .. o 

w 

Platform Side 

Figure 7 . Mean fish density (number of fish / m ') by platform side from Green Canyon 18 

(GC 18) and Grand Isle 94 (GI94) from July 1994 to March 1997 and South Timbalier 54 (ST54) 

from August 1995 to February 1997. 

143 

East North South West 
5 -' 

15 

`r 

.L 

d 25 

it I 35 

45 -i 

55 -t---- 

0 

Fish density ( number / m) 

1 

Figure 8 . Mean fish density (number of fish /M3 ) by depth at Grand Isle 94 (GI94) from July 1994 to 

March 1997 and South Timbalier 54 (ST54) from August 1995 to February 1997 . 

144 

0.2 0.4 0.6 0.8 
Dissolved oxygen (ppm) 

c. 

^C 

t. 

0 2 4 6 8 10 12 

I ;I 

~~~ I! 

5 ~ ~'' 

1/010 

I III 000000 

I 000 I~ Fish Density (Y1) io 

I Dissolved Oxygen (Y2) 

0100 i -, _-

15 I~ I r 

20 

I 

i 

0 0.1 0 .2 0.3 0.4 0.5 0.6 

Fish density ( number / m3) 

Figure 9 . Mean fish density (number of fish / m3) and dissolved oxygen (ppm) by depth at South 

Timabalier 54 from July 1996 . 

145 
i. 

a> 

C 

t7 

A 

(/1 

.r .~ 

w 

a . .. 

0.3 

0.25 

0.2 

0.15 

0 .1 

0 .05 

0 

Distance from Platform (m) 

Figure 10 . Mean relative fish density (number of fish / m ') by distance from the platform at Green 

Canyon 1 8 (GC 18) and Grand isle 94 (Gi94) from July 1994 to March 1997 and South Timbalier 54 

(ST54) from August 1995 to February 1997. 

146 

10 18 26 34 42 50 58 66 74 82 
70000 --r 

~. i 

C~ I 

60000 

50000 

w 

40000 

d 

I 

30000 

z 

Zoooo ~ 

. 8 . . ioooo 

y 

O 1 

Sum Fall 

1994 

ST54 

°°°°°" GI94 

Figure 11 . Estimated number of bluerunner for each quarterly sample period at Green Canyon 1 8 

(GC 18) and Grand Isle 94 (GI94) from July 1994 to March 1997 and South Timbalier (ST54) from 

August 1995 to February 1997 . 

147 

Win Sum Fall Win Spr Sum Fall Win 

1995 1996 1997 

Sample Period 
70000 

60000 

w 

w 

50000 i. 

E 40000 

z 

'b 30000 

20000 

W 

10000 

7 

Figure 12. Estimated number of fishes for each quarterly sample period at Green Canyon 18 (GC 18) and 

Grand Isle 94 (GI94) from July 1994 to March 1997 and South Timbalier (ST54) from August 1995 to 

February 1997 . 

CTGA 

148 

-T- -1 TSum Fall Win Sum Fall Win Spr Sum Fall Win 

1994 1995 1996 1997 

Sample Period 
5000 

VJ 

4000 

c 

3000 

r 

i 

b 2000 --~ ~-

i 

1000 

J 

0 .zre.t,* Tr 

Sum Fall Win Sum Fall Win Spr Sum Fall Win 

1994 1995 1996 1997 

Sample Period 

Figure 13 . Estimated number of greater amberjack, horseeye jack, mangrove snapper and red snapper 

fishes for each quarterly sample period at Grand Isle 94 (GI94) from July 1994 to March 1997 . 

---- Greater Amberjack 

""" " ""

' 

Horseeye Jack 

Mangrove Snapper 

-~-~ Red Snapper 

149 
O 

3 5 .I 

75 8 

sa w+ 

a. 

115 --' 

CE I 

155 

195-L0 0 .05 

' I ~I 

I 

-1- 

GC18 

-

I 

II I 

- - 

0.1 0.15 0.2 0.25 0.3 

Fish Density ( number / m3) 

Figure 14. Mean fish density (number offish / m') by depth at Green Canyon 18 from October 1994 

to March 1997. 

150 

0.35 0 .4 
12000 --r 

Greater Amberjack 

Almaco Jack 

1000 

Barracuda 

I 

-"-"-"" Creole8sh 

8000 ""'°""' Bermuda Chub I 

I 1 4f 

j + 6000 ~ 1--1--~ - -~- - ~- 

e .4f 

4000 V- - Ae 

ii ~ i 

2000 

h 

d 

.Ly 

H 

fir 

w 

0 

7 

z b 

8 ... 

w 

Sum Fall Win Sum Fall Win Spr Sum Fall Win 

1994 1995 1996 1997 

Sample Period 

Figure I5 . Estimated number of greater am berjack, almaco jack, barracuda, ere olefish and 

Bermuda chub for each quarterly sample period at Green Canyon 18 from October 1994 to March 

1997 . 

151 

APPENDIX 1 

Current, Temperature, Salinity and Oxygen Data Coincident 

with Acoustic Data at South Timbalier 54 

153 
45 

4C1 

35 

E 30 

U 

-025 

X20 

4-0 

151 

01a 

5 

Dawn (Y1) ---- Noon (Y1) 

. . . . . . Dusk (Y1) -~-~-~- Midnight (Y1) 

I " Dawn (Y2) + Noon (Y2) 

" Dusk (Y2) x Midnight (Y2) 

1 

--- 

i 

i -T~ I 

0 5 10 15 20 

Depth (m) 

Appendix 1-1 . Plot of current speed and direction 

with depth coincident with acoustic data at South 

Timbalier 54 from October 24-25, 1995 . 

360 

300 0 

m 

?40 

0 

180 0 

Q 

120 

m 

i0 

154 
Dawn ---- Noon 

Dusk -'-'-'- Midnight 

--- 

35 ~ - --- 

30 

U 

0 

L 

L v 

. ~i .i .iiii .i . 

. . 

L 

----

I 15 

0 5 10 15 

Depth (m) 

Appendix 1-2 . Plot of temperature and water depth 

coincident with acoustic data at South Timbalier 54, 

October 24-25, 1995 . 

20 

155 
Dawn - - - - Noon 

Dusk Midnight 

40 , 

35 

30 

25 

i U) 

20~ 

15 

10 

0 5 10 15 20 

Depth (m) 

Appendix 1-3 . Plot of salinity with depth coincident with 

the collection of acoustic data at South Timbalier 54 

from October 24-25, 1995 . 

156 
Dawn ---- Noon 

Dusk -'-'-'- Midnight 

10 

Q 

Q. 

X 

0 

CJ 

6~ 

4 ; 

2 O 

0- 

0 5 10 15 20 

Depth (m) 

Appendix 1-4 . Plot of depth with dissolved oxygen 

coincident with acoustic data at South Timbalier 54, 

October 24-25, 1995 . 

157 
Dawn (Y1) ---- Noon (Y1) 

Current Speed ' '!I 

Dusk (Y1) -'-'-'- Midnight (Y1) 

Current Direction " Dawn (Y2) + Noon (Y2) 

I " Dusk (Y2) X Midnight (Y2) 

35 - - 360 

-- 30 f 300 n 

25 ------~-_------ 

40 a 

~ 20 

180 0. 

cn 15 

. . . 120 c.CQD 

_-

, . . . . . . . . . 10 CD 

160 

-~ - - . 

0 5 10 15 20 

Depth (m) 

Appendix 1-5 . Plot of current speed and direction 

with depth coincident with acoustic data at South 

Timbalier 54 from January 30 - February 1, 1996 . 

158 
35 

30 

U 

0 

L 

25-

L 

20 

I-- 

15 

i 

~I Dawn 

I . . . ., . . . . . . . Dusk 

---- Noon 

Midnight 

0 5 10 15 

Depth (m) 

Appendix 1-6 . Plot of temperature and water depth 

coincident with acoustic data at South Timbalier 54, 

January 30 - February 1, 1996 . 

20 

159 
Dawn ---- Noon 

Dusk -'---'- Midnight 

a 

x 

O 

0 

D 

10 ~~ 

_ " .. .. 

. . . . ., ., 

6 ;. 

4 

2'I 

0

.-

0 5 10 15 20 

Depth (m) 

Appendix 1-8 . Plot of depth with dissolved oxygen 

coincident with acoustic data at South Tim balier 54, 

January 30 - February 1, 1996 . 

160 
Current Speed 

Current Direction!ll 

45 

40 

34 

E 34 

-025 

20 

X15 L 

v10 

5 

0 

Dawn (Y1) 

Dusk (Y1) 

" Dawn (Y2) 

" Dusk (Y2) 

---- Noon (Y1) 

-~-'-'- Midnight (Y1) 

+ Noon (Y2) 

Midnight (Y2) 

~- 

----- __------- X- 

=~-_ - - 

------------- 

- - 

- ---- 

360 

300 

-, 

0 

240 

01 CD Ito 0 

C'80 ° 

0-

120 cn 

60 1-1 

0 

0 5 10 15 20 

Depth (m) 

Appendix 1-9. Plot of current speed and direction 

with depth coincident with acoustic data at South 

Timbalier 54 from June 6-7, 1996 . 

161 
--- 

Dawn ---- Noon 

I . . ., . . . . ., . . . . Dusk Midnight 

35 r 

30 

U 0 

L 

25 

L 

r 

20 

15 

0 5 10 15 20 

Depth (m) 

Appendix 1-10 . Plot of temperature and water depth 

coincident with acoustic data at South Timbatlier 54, 

June 6-7, 1996 . 

162 
- ---

Dawn 

. . . . . . . . . . . . . . Dusk 

40 ~- 

35 

30 

4-0 

.~ 25 

ca cn20 

15~ 

10I 

---- Noon 

------- Midnight 

0 5 10 15 20 

Depth (m) 

Appendix 1-11 . Plot of salinity with depth coincident with 

the collection of acoustic data at South Timbalier 54 

from June 6-7, 1996 . 

163 
Dawn 

', . . . . . . . . . . . . . . Dusk 

10 -- I 

8 

.-. 

a 

6 

, . . 

x 

O 

4 r 

0 

D 21- 

` `` -. 

s 

0 .-- 

0 5 10 15 20 

Depth (m) 

Appendix 1-12 . Plot of depth with dissolved oxygen 

coincident with acoustic data at South Timbalier 54, 

June 6-7, 1996 . 

--- 

---- Noon 

-'-'-'- Midnight 

_---- 

164 
Current Speed I Dawn (Y1) ---- Noon (Y1) 

""""""" Dusk (Y1) -'----- Midnight (Y1) 

Current Direction " Dawn (Y2) + Noon (Y2) 

" Dusk (Y2) x Midnight (Y2) 

----360 

4 ---~ -- __ -- 

300 

35 ---- - 

U) X CD 

E 30 --__-~~--~, 240 U ~ Q 

25 

-- .   , . - . - 1 80 . a20 ~ ° 

L 15 _-- -`, . . ~ X120 L 

c~ m 10 

- 60 

5 -- 

0 --_-~ -- I'0 

0 5 10 15 2Q 

Depth (m) 

Appendix 1-13 . Plot of current speed and direction 

with depth coincident with acoustic data at South 

Timbalier 54 from July 17-18, 1996 . 

165 
35~ 

30 

U 

0 

L 

25 

L 

Q. 

20 

Dawn 

. . . . . . . . . . . . . . Dusk 

---

---- Noon 

-'-'-'- Midnight 

15~ 

0 5 10 15 20 

Depth (m) 

Appendix 1-14 . Plot of temperature and water depth 

coincident with acoustic data at South Timbalier 54, July 

17-18, 1996 . 

166 
I I Dawn ---- Noon i 

""""""" Dusk ------- Midnight 

I - _ J 

40 

35 

30 

a 

.~ 25 

CO 

20 

15 

10 I~- 

0 5 10 15 20 

Depth (m) 

Appendix 1-15 . Plot of salinity with depth coincident with 

the collection of acoustic data at South Timbalier 54 

from July 17-18, 1996 . 

167 
----, 

Dawn ---- Noon 

""""""" Dusk -'----- Midnight 

10 r8 ~ -- __ 

a 

--- 

x 0 

4 

0 

D 

0 

0 5 10 15 20 

Depth (m) 

Appendix 1-16 . Plot of depth with dissolved oxygen 

coincident with acoustic data at South Timbalier 54, 

July 17-18, 1996 . 

168 
Dawn (Y1) ---- Noon (Y1) 

Current Speed 

Dusk (Y1) ------- Midnight (Y1) 

Current Direction " Dawn (Y2) + Noon (Y2) 

" Dusk (Y2) X Midnight (Y2) ~I 

-- ; 

360 

40 -_ - - -1 

300 

35 

. . . . . . . .,, .r.' A --~ 

-- - -- 

m 

\ ~~` ~ ~= ~ E 30 a 240 

(D ---- r -- ~ t - 

180 0 

cn 20 

15 ---- '~ ~ 120 L 

U 1 

t 60 

5 "" w 

I 0 5 10 15 20 

Depth (m) 

Appendix 1-17 . Plot of current speed and direction 

with depth coincident with acoustic data at South 

Timbalier 54 from August 30-31, 1996 . 

169 
Dawn 

. . . . . . . . . . . . . . Dusk 

35 

30 

U 

0 

L I 25 

L ^`

W 

W 

L . 

I 15t 

---- 

I 

---- Noon I 

-'-'-'- Midnight I 

0 5 10 15 

Depth (m) 

Appendix 1-18 . Plot of temperature and water depth 

coincident with acoustic data at South Timbalier 54, 

August 30-31, 1996 . 

20 

170 
Dawn ---- Noon I 

II 

. . . . . . . . . . . . . . Dusk ------- Midnight 

40 ~- 

35 

30 

Q. 

.>25 ._ 

CO 20 

15 

10I 

0 5 10 15 20 

Depth (m) 

Appendix 1-19 . Plot of salinity with depth coincident with 

the collection of acoustic data at South Timbalier 54 

from August 30-31, 1996 . 

171 
I Dawn 

. . . . . . . . . . . . . . Dusk 

10 

a 

a 

0 

8 II- 

---- Noon 

Midnight 

61- 

1` ;` 

4 

~~+.. 

2 0 

0 

0 5 10 15 20 

Depth (m) 

Appendix 1-20 . Plot of depth with dissolved oxygen 

coincident with acoustic data at South Timbalier 54, 

August 30-31, 1996 . 

172 
Current Speed 

Current Direction 

45~ 

4 I--

35 

E 30 

U 

-0 25 

Dawn (Y1) 

""""""" Dusk (Y1) 

" Dawn (Y2) 

" Dusk (Y2) 

---- Noon (Y1) 

-'-'-'- Midnight (Y1) 

+ Noon (Y2) 

Midnight (Y2) I 

- 360 

, 300 0 

m 

---- . ~ 240 

(D 

180 

0 

. 

Con- 20 - - 

0 

cD a) 120 C 

m 

-- - " " ' . , 

,, .,60 - ., 5 -- 

. . . 

-----

Ilr 

0 5 10 15 20 

Depth (m) 

Appendix 1-21 . Plot of current speed and direction 

with depth coincident with acoustic data at South 

Timbalier 54 from October 24-25, 1996 . 

173 
35 

30 

U 

0 

L 

25 

L 

20 

Dawn 

i 

. . . . . . . . ., Dusk 

---- Noon 

-'-'-'- Midnight 

15 r0 5 10 15 20 

Depth (m) 

Appendix 1-22 . Plot of temperature and water depth 

coincident with acoustic data at South Timbatlier 54, 

October 24-25 1996 . 

174 
j Dawn ---- Noon 

III ~ . . . . . . . . . . . . . Dusk ------ - Midnight 

--- -- -- -- -- --- - -- 

_ 

__-] 

40 

35 

30 

25 

(D 

20 

15 

10 

Appendix 1-23 . Plot of salinity with depth coincident with 

the collection of acoustic data at South Timbalier 54 

from October 24-25, 1996 . 

175 

0 5 10 15 20 

Depth (m) 
Dawn - - - - Noon 

""""""" Dusk -'-'-'- Midnight 

10~ 

V ----- 

E 

. 

l~- 

Q I 

6 

x 

O 

a 

0 

0 --r 

0 5 10 15 20 

Depth (m) 

Appendix 1-24 . Plot of depth with dissolved oxygen 

coincident with acoustic data at South Timbalier 54, 

October 24-25, 1996 . 

176 
Current Speed 

Dawn (Y1) 

. . . . . . . . . . . . . . Dusk (Y1) 

Current Direction " Dawn (Y2) 

3 

30 F 

25 

U 

a 

X15 

c 

X10 

U 

5 

r--_~ -, 

n 

180 0 

a 

120 cn 

CD 

m 

I60 

T7 I 

0 5 10 15 20 

Depth (m) 

Appendix 1-25 . Plot of current speed and direction 

with depth coincident with acoustic data at South 

Timbalier 54 from January 30 - February 1, 1997 . 

" Dusk (Y2) 

---- Noon (Y1) 

-'-'-'- Midnight (Y1) 

+ Noon (Y2) 

Midnight (Y2) 

_ --, 360 

-----~--fi300 

-~ 

_ 

,240 

177 
Dawn 

', . . . . ., . . . . . . . . Dusk 

35 

30 

U 

0 

L 

25 

L 

20 

15 

---- Noon 

-'-'-'- Midnight ~I 

0 5 10 15 20 

Depth (m) 

Appendix 1-26 . Plot of temperature and water depth 

coincident with acoustic data at South Timbatlier 54, 

January 30 -February 1, 1997 . 

178 
----- 

Dawn ---- Noon 

Dusk ------- Midnight 

40 

35 

30 

4-0 

25 

U) 

20 

15 

10 

Appendix 1-27 . Plot of salinity with depth coincident with 

the collection of acoustic data at South Timbalier 54 

from January 30 - February 1, 1997 . 

179 

0 5 10 15 20 

Depth (m) 
Dawn - - - - Noon 

""""""" Dusk ------- Midnight 

10 ; ---------- 

U 

C III 

L2. 

Q 

x 

O 

a 4 

o 

D I 2 

0 !_ 

0 

- - ---

5 10 

Depth (m) 

15 20 

Appendix 1-28 . Plot of depth with dissolved oxygen 

coincident with acoustic data at South Timbalier 54, 

January 30 -February 1, 1997 . 

180 
APPENDIX 2 

Current, Temperature, Salinity and Oxygen Data Coincident 

with Acoustic Data at Grand Isle 94 

181 
Current Speed 

Dawn (Y1) ---- Noon (Y1) 

Dusk (Y1) -'-'-'- Midnight (Y1) 

Current Direction " Dawn (Y2) + Noon (Y2) 

Dusk (Y2) X Midnight (Y2) 

60 

501 

E 40 

U 

a> 

030 

4-1 

c 

~' 2 0 

U ' 

10 

360 

300 

I 

240 a 

(D 0 

180 0 

a 

120 co 

i m 

60 

o T- --,- -7 0 

5 10 15 20 25 30 35 40 45 50 55 60 

Depth (m) 

Appendix 2-1 . Plot of current speed and direction 

with depth coincident with acoustic data at Grand 

Isle 94, October 12-13, 1994 . 

_ _ -- I 

'f' 

- 

+ 

---- 

--~~ 

---- 

+ I 

I 

X 

-- 

i ~t 

.010 

- --x 

182 
Dawn ---- Noon 

Dusk -'----- Midnight 

30 

25 

U'20 

0 

L 

X15 

I 

I 

E 10f 

5, 

0 ~ --T - - -~ _T _ 

0 5 10 15 20 25 30 35 40 45 50 55 

Depth (m) 

Appendix 2-2 . Plot of temperature and water depth 

coincident with acoustic data at Grand Isle 94, October 

12, 1994 . 

183 
---

Dawn ---- Noon 

Dusk Midnight 

40 

35 

30 

25 

5 10 15 20 25 30 35 40 45 50 55 60 

Depth (m) 

Appendix 2-3 . Plot of salinity with depth coincident with 

the collection of acoustic data at Grand Isle 94, October 

12, 1994 

184 
Dawn ---- Noon 

"""" Dusk -'-'-'- Midnight 

c 

x 7 

O 

-a i 

0 

D 

4 - i -~- 

5 10 15 20 25 30 35 40 45 50 55 60 

Depth (m) 

Appendix2-4 . Plot of temperature and dissolved 

oxygen coincident with acoustic data at Grand Isle 94, 

October 12, 1994 . 

185 
Dawn (Y1) ---- Noon (Y1) 

Current Speed il , . . . Dusk (Y1) -~-~-~- Midnight (Y1) 

Current Directionll, " Dawn (Y2) + Noon (Y2) 

" Dusk (Y2) X Midnight (Y2) 

60 ----- -- 360 X 

~-- 

5 300 

E 40 

U 

Q 30 

~ 20 L 

U 

10 

180 

120 

60 

---- -- x+ _--ij.'0,, 240 

I^~~ft, --% 

,) ,-

, ` 

- " , , 

I 

0 AAMNL 

5 10 15 20 25 30 35 40 45 50 55 60 

Depth (m) 

Appendix 2-5 . Plot of current speed and direction 

with depth coincident with acoustic data at Grand Isle 

94, January 30-31, 1995 . 

n 

Q 

(D 

O 

a 

m 

186 
35 

301 

U 0 

L 

25 

L 

20 ~- 

15 '~-

5 

Dawn 

', . . . . . . . . . . . . . . Dusk 

-- - 

---- Noon 

-'-'-'- Midnight I' 

.~ ~~~,~~STT` 

10 15 20 25 30 35 40 45 50 55 60 

Depth (m) 

Appendix 2-6 . Plot of temperature and water depth 

coincident with acoustic data at Grand Isle 94, January 

30-31, 1995 . 

187 
I, Dawn 

. . . . . . . . . . . . . . Dusk 

40 r--- 

35 

~ 30 

---- Noon 

-'-'-'- Midnight 

25~ 

5 10 15 20 25 30 35 40 45 50 55 60 

Depth (m) 

Appendix 2-7 . Plot of salinity with depth coincident with 

the collection of acoustic data at Grand Isle 94, January 

30-31, 1995 . 

188 
i -- 

Dawn ---- Noon 'I 

Dusk .. .. . . - Midnight ', 

10, 

9' 

a. 

c 

x 7 

O 

a) 

-' 0 6 

D 

II -r--- 

5 10 15 20 25 30 35 40 45 50 55 60 

Depth (m) 

Appendix 2-8 . Plot of temperature and dissolved 

oxygen coincident with acoustic data at Grand Isle 94, 

January 30-31, 1995 . 

189 
Current Speed F- Dawn (Y1) --- Noon (Y1) 

I Dusk (Y1) -~-~-~- Midnight (Y1) 

Current Direction, " Dawn (Y2) + Noon (Y2) 

~ Dusk (Y2) x Midnight (Y2) 

60 360 

50 300 0 

CD 

CD 

0 

80 c:2~ CL 0 

Cn 

Q. 

a) CD 2 20 120 

C D 

(D (n 60 

~---

5 10 15 20 25 30 35 40 45 50 55 60 

Depth (m) 

Appendix 2-9 . Plot of current speed and direction 

with depth coincident with acoustic data at Grand Isle 

94, September 11-13, 1995 . 

190 
Dawn 

. . . . . . . . ., . . . . Dusk 

35 ~_ 

30 

U 0 

a) L 

25 

L 

a 

H 

20 

- - - - Noon -

-'-'-~- Midnight 

- - -1 

15 ~- - ~ 

5 10 15 20 25 30 35 40 45 50 55 60 

Depth (m) 

Appendix 2-10 . Plot of temperature and water depth 

coincident with acoustic data at Grand Isle 94, 

September 11-13, 1995 . 

191 
Dawn ---- Noon 

""""""" Dusk .. .. .. . Midnight 

III - . 

40 

35 

a 

a 

U) 

30 

25 

5 10 15 20 25 30 35 40 45 50 55 60 

Depth (m) 

Appendix 2-11 . Plot of salinity with depth coincident 

with the collection of acoustic data at Grand Isle 94, 

Septem ber 11-13, 1995 . 

192 
Dawn - - - - Noon 

""""""" Dusk .. .. .. - Midnight 

`= 

_._ ., 

. - ,. . : . 

N ` 

X 

> 5 

o ~-

.Cn 

D 

4 ~- -~--~ 

5 10 15 20 25 30 35 40 45 50 55 60 

Depth (m) 

Appendix 2-12 . Plot of temperature and dissolved 

oxygen coincident with acoustic data at Grand Isle 94, 

September 11-13, 1995 . 

193 
Current Speed 

Current Direction 

60 

50 

E 4 

U 

~' 3 

4-0 

c 

Dawn (Y1) 

Dusk (Y1) 

" Dawn (Y2) 

" Dusk (Y2) 

--- Noon (Y1) 

Midnight (Y1) 

+ Noon (Y2) 

Midnight (Y2) 

360 

{300 

1240 a 

(D 0 

180 0 

a 

- . .-,- . . . . . . ., 12 0 

Cj ,~`` ~' ~ + N 

... 

60 

~ r. _ _, ~ ~C + + o 

5 10 15 20 25 30 35 40 45 50 55 60 

Depth (m) 

Appendix 2-13 . Plot of current speed and direction 

with depth coincident with acoustic data at Grand Isle 

94, November 14-16, 1995 . 

194 
Dawn ---- Noon 

Dusk ------- Midnight 

35 

30 

.-

U 0 

L 

25 

L 

20 

1 5 

5 10 15 20 25 30 35 40 45 50 55 60 

Depth (m) 

Appendix 2-14 . Plot of temperature and water depth 

coincident with acoustic data at Grand Isle 94, 

November 14-16, 1995 . 

195 
--- ---

I Dawn ---- Noon 

""""""" Dusk .. . . . . . Midnight 

---- 

40 

35 

ca U) 

30 

25 ~~~---

5 10 15 20 25 30 35 40 45 50 55 60 

Depth (m) 

Appendix 2-15 . Plot of salinity with depth coincident with 

the collection of acoustic data at Grand Isle 94, 

November 14-16, 1995 . 

196 
Dawn ---- Noon 

""""""" Dusk ------- Midnight 

10 -

9 

g 

x 7 - --- 

, . ., 

, . -. N ., 

- 6 o ~- ---

5 

5 10 15 20 25 30 35 40 45 50 55 60 

Depth (m) 

Appendix 2-16 . Plot of temperature and dissolved 

oxygen coincident with acoustic data at Grand Isle 94, 

November 14-16, 1995 . 

197 
Current Speed 

Current Direction 

60 X-- 

50" -

E 40 

U .}. 

~ 30 

4-0 

---- Noon (Y1) 

Midnight (Y1) 

+ Noon (Y2) 

Midnight (Y2) 

360 

0-0- """ -

X300 n 

---- + 

x+ ---~,I 240 

III . 

CD 0 

----_- - ' 180 0 

c 

- 

Q 

120 coo 

~-- 10 --~---- _- - ~ 60 

I , ., . . 

I ~ r' L~, `~~, 

a 

o ) ON A, T5 10 15 20 25 30 35 40 45 50 55 60 

Depth (m) 

Appendix 2-17 . Plot of current speed and direction 

with depth coincident with acoustic data at Grand Isle 

94, January 30-31,1996 . 

Dawn (Y1) 

Dusk (Y1) 

" Dawn (Y2) 

" Dusk (Y2) 

198 
Dawn 

. . . . . . . . . . . . . . Dusk 

35 

30 ~ 

U 

0 

L 

25 

L 

20 

---- Noon 

-'-'-'- Midnight 

15 ~ ---- ~ ~ T - -- T5 10 15 20 25 30 35 40 45 50 55 60 

Depth (m) 

Appendix 2-18 . Plot of temperature and water depth 

coincident with acoustic data at Grand Isle 94, February 

13-14, 1996 . 

199 
Dawn ---- Noon 

j . . . . . . Dusk ------- Midnight 

40 

35 

a 

30 

2 5 T---T--T5 10 15 20 25 30 35 40 45 50 55 60 

Depth (m) 

Appendix 2-19 . Plot of salinity with depth coincident with 

the collection of acoustic data at Grand Isle 94, 

February 13-14, 1996 . 

200 
~6 

x 

0 -a 

-5 ' 0 

O 

Dawn 

. . . ., ., . . . . . . . Dusk 

---- Noon ', 

-'-'-'- Midnight I, 

4 

5 10 15 20 25 30 35 40 45 50 55 60 

Depth (m) 

Appendix 2-24 . Plot of temperature and dissolved 

oxygen coincident with acoustic data at Grand Isle 94, 

April 23-25, 1996 . 

201 
Dawn 

, . . . . . . . . . . . . . Dusk 

35 ~- 

30 

U 

0 

a) 

L 

m L 25 ~-i 

r 

20 

., 

15 

5 10 15 20 25 30 35 40 45 50 55 60 

Depth (m) 

Appendix 2-22 . Plot of temperature and water depth 

coincident with acoustic data at Grand Isle 94, April 23-

25,1996 . 

---- Noon 

Midnight 

202 
Dawn (Y1) ---- Noon (Y1) 

Current Speed '  Dusk (Y1) -~-~-~- Midnight (Y1) ', 

Current Direction' " Dawn (Y2) + Noon (Y2) I, 

" Dusk (Y2) X Midnight (Y2) 

60 ~- " -X360 

i .,~ . 

50 ~ - -*300 0 

E 40 240 

a) n 

30 180 0 

oa "'- cD 

~ 20 --~- +120 L 

`~ ,` 

10 '60 

`-~~~~I X 

0 - - --~ -- + r 0 

5 10 15 20 25 30 35 40 045 50 55 

Depth (m) 

Appendix 2-21 . Plot of current speed and direction 

with depth coincident with acoustic data at Grand Isle 

94, April 23-25, 1996 . 

203 
f 

Dawn ---- Noon 

Dusk Midnight 

40 

35 

a 

a 

~ 30 

25 - ~ --T-~~ - -, 

5 10 15 20 25 30 35 40 45 50 55 60 

Depth (m) 

Appendix 2-23 . Plot of salinity with depth coincident with 

the collection of acoustic data at Grand Isle 94, April 23-

25, 1996 . 

204 
Current Speed 

Current Direction i 

60 

504 

E 40 

U 

Q 30 

20 L 

U 

10 

360 

X300 

-, 

0 

240 a 

(D. n 

180 0 

Q 

X120 

60 1-1 

5 10 15 20 25 30 35 40 45 50 55 60 

Depth (m) 

Appendix 2-25 . Plot of current speed and direction 

with depth coincident with acoustic data at Grand Isle 

94, November 5-6, 1996 . 

Dawn (Y1) 

""""""" Dusk (Y1) 

" Dawn (Y2) 

" Dusk (Y2) 

---- Noon (Y1) 

-'-'-'- Midnight (Y1) 

+ Noon (Y2) 

Midnight (Y2) " 

- --- - -I 

- -- - 

y 

-~- X 

I 

__ P 

_ - -~ - - -- - 

. "~ 

-- x -,' 

' ~ --, "---,, 

205 
i ----- 

Dawn 

', . . . . . . . . . . . . ., Dusk 

35 1 - 

30 

U 

0 

a) 

L 

25 

a 

H 

20 

---- Noon 

Midnight 

15 

5 10 15 20 25 30 35 40 45 50 55 60 

Depth (m) 

Appendix 2-26 . Plot of temperature and water depth 

coincident with acoustic data at Grand Isle 94, 

November 5-6, 1996 . 

206 
Dawn 

. . . . . . . , . . . . . . Dusk 

35 

a 

c 

~ 30 

---- Noon 

-'-'-'- Midnight 

. " 

25 

5 10 15 20 25 30 35 40 45 50 55 60 

Depth (m) 

Appendix 2-27 . Plot of salinity with depth coincident with 

the collection of acoustic data at Grand Isle 94, 

November 5-6, 1996 . 

207 
Dawn - - - - Noon 

""""""" Dusk -'-'-'- Midnight 

10 

9 

x 

O 

a) 

0 

8 

7 

6 

D 

_-1 

5 10 15 20 25 30 35 40 45 50 55 60 

Depth (m) 

Appendix 2-28 . Plot of temperature and dissolved 

oxygen coincident with acoustic data at Grand Isle 94, 

November 5-6, 1996 . 

208 
Dawn (Y1) 

Current Speed 

I Dusk (Y1) 

Current Direction " Dawn (Y2) 

" Dusk (Y2) 

60 

50 

i 

E 40 

U 

~ 30 fl . 

c 

' 20 

U 

10 

300 0 

240 

n. 180 0 

a 

120 cc 

m 

X60 

1 

5 10 15 20 25 30 35 40 45 50 55 60 

Depth (m) 

Appendix 2-29 . Plot of current speed and direction 

with depth coincident with acoustic data at Grand Isle 

94, March 3-4, 1997 . 

-F + 

.~. X~- ~ 

AL 

x 

A -1 

i 

--- - - 

., , .., , . . N" , ' 

`--- - -- 

---- Noon (Y1) 

Midnight (Y1) II 

+ Noon (Y2) 

Midnight (Y2) I, 

360 

209 
Dawn 

. . . . . . . . . . . . . . Dusk 

35 

30 

U 0 

L 

25 

L 

I 

20 

---- Noon 

Midnight 

5 10 15 20 25 30 35 40 45 50 55 60 

Depth (m) 

Appendix 2-30 . Plot of temperature and water depth 

coincident with acoustic data at Grand Isle 94, March 3-

4, 1997 . 

210 
Dawn ---- Noon 

Dusk -'-'-'- Midnight 

40~-- 

35 

a 

ca CO 

30 

25 'r 

5 10 15 20 25 30 35 

Depth (m) 

40 45 550 55 60 

Appendix 2-31 . Plot of salinity with depth coincident with 

the collection of acoustic data at Grand Isle 94, March 

3-4, 1997 . 

211 
Dawn ---- Noon 

""""""" Dusk -'-'-'- Midnight 

10~ - 

911------ 

E 

a g 

c 

x 7 

O 

W 

0 

i 

i D 

5 

5 10 15 20 25 30 35 40 45 50 55 60 

Depth (m) 

Appendix 2-32 . Plot of temperature and dissolved 

oxygen coincident with acoustic data at Grand Isle 94, 

March 3-4, 1997 . 

212 
APPENDIX 3 

Current, Temperature, Salinity and Oxygen Data Coincident 

with Acoustic Data at Green Canyon 18 

213 
Dawn (Y1) ---- Noon (Y1) 

""""""" Dusk (Y1) -~-~-~- Midnight (Y1) ', 

" Dawn (Y2) + Noon (Y2) 

" Dusk (Y2) x Midnight (Y2) ', 

7 +- ~- -----_- -~~ I 360 

60 --X -- X - 300 I 

p -- 

, 240 

-o 40 CD 

" 180 0 a 

cn 0 ~--- 

.- . Q 

1 120 cS D

10 60 

_,_ "' 

v 

~T ~I~ i i ~Iw+ 

10 30 50 70 90 110 130 150 170 190 

Depth (m) 

Appendix 3-1 . Plot of current speed and direction 

with depth coincident with acoustic data at Green 

Canyon 18, November, 29, 1994 . 

214 
Dawn ---- Noon 

"""""""' Dusk . . . . . . - Midnight 

30 

25 

U 

0 

L 

20 

L 

15 

10 -,--

10 30 50 70 90 110 130 150 170 190 210 

Depth (m) 

Appendix 3-2 . Plot of temperature and water depth 

coincident with acoustic data at Green Canyon 18, 

November 29, 1994 . 

215 
Dawn ---- Noon - -

Dusk ------- Midnight 

40!r--- 

35 

-~ ---

30 

25 

20 ~~~- -.-- ----- - 

10 30 50 70 90 110 130 150 170 190 210 

Depth (m) 

Appendix 3-3 . Plot of depth with salinity coincident 

with acoustic data at Green Canyon 18, November 

29, 1994 . 

216 
Dawn 

. . . ., ., . . . . . . . Dusk 

10! 

8 ~ 

a 

x 6 

O 

0 

0 4 ! 

---- Noon 

-'-'-'- Midnight 

2 ,- 

10 30 50 70 90 110130150170190210 

Depth (m) 

Appendix 3-4 . Plot of depth with dissolved oxygen 

coincident with acoustic data at Green Canyon 18, 

November 29, 1994 . 

217 
--

IDawn (Y1) ---- Noon (Y1) 

Current Speed I 

""""""" Dusk (Y1) -~-~-~- Midnight (Y1) 

Current Direction " Dawn (Y2) + Noon (Y2) 

" Dusk (Y2) X Midnight (Y2) 

--- - -- 

360 

70 _- -- --

300 n 60 -- ---- 

m 

E 50 -_ ~- 240 

m 

40 

~ 

- - 

180 0 a 

30 

X120 

0 (D 

X (n 

60 1 ~ 

0 --T F 0 

10 30 50 70 90 110 130 150 170 190 

Depth (m) 

Appendix 3-5 . Plot of current speed and direction 

with depth coincident with acoustic data at Green 

Canyon 18, February . 22-23, 1995 . 

218 
Dawn ---- Noon 

I, . . . . . . . . . . . . . . Dusk _,_,_,_ Midnight 

30 

25 

U 0 

L 

20 

L 

15 

10 '~1----- 1---~----- -- 

10 30 50 70 90 110 130 150 170 190 210 

Depth (m) 

Appendix 3-6 . Plot of temperature and water depth 

coincident with acoustic data at Green Canyon 18, 

February 22-23, 1995 . 

219 
40 

----

Dawn 

II, . . . . . . . . . . . . Dusk 

35 ~ --_ 

I 

.~ 30 

25' 

---- Noon 

-'-'--- Midnight 

20 

10 30 50 70 90 110 130 150 170 190 210 

Depth (m) 

Appendix 3-7 . Plot of salinity with depth coincident with 

the collection of acoustic data at Green Canyon 18, 

February 22-23, 1995 . 

220 
10 

Dawn 

. . . . ., . . . ., .  Dusk 

a. 

x 6~ r 

o 

o 

0 4i 

---- Noon 

-'-'-'- Midnight j _ . i 

IVA 

. , 

IL-~T - ------ 2 ;1 ~ -- 

10 30 50 70 90 110130150170190210 

Depth (m) 

Appendix 3-8 . Plot of depth with dissolved oxygen 

coincident with acoustic data at Green Canyon 18, 

February 22-23, 1995 . 

221 
----_ -,i 

Current Speed ' Dawn (Y1) ---- Noon (Y1) 

Dusk (Y1) ------- Midnight (Y1) 

Current Direction I , Dawn (Y2) + Noon Y2 

I' Dusk (Y2) x Midnight (Y2) 

----- --- - -

60 

70 

n .3100 60 - 

E 50 ~ 240 a ` . 

CD 

a~ 40 ~ 

! 0 

,~ x X X I 180 0 

J( X 

30 CL 

L 120 

0 CD 2 CD 

" ` TTS~f,

,/` 10 30 50 70 90 110 130 150 170 190 

Depth (m) 

Appendix 3-9 . Plot of current speed and direction 

with depth coincident with acoustic data at Green 

Canyon 18, April 3-4, 1995 . 

222 
--

Dawn ---- Noon 

Dusk . . . . . . - Midnight 

30 ; 

25 

U 

0 

a) 

2 o 

a) 

ca. 

E a) 

1-- 

15 

101 

10 30 50 70 90 110 130 150 170 190 210 

Depth (m) 

Appendix 3-10 . Plot of temperature and water depth 

coincident with acoustic data at Green Canyon 18, April 

3-4, 1995 . 

223 
-- -

Dawn ---- Noon 

. . . . . . . . . . . . . . Dusk ------- Midnight 

40 

35 

30 

25 

20 ~--- --r---- --- 

10 30 50 70 90 110 130 150 170 190 210 

Depth (m) 

Appendix 3-11 . Plot of salinity with depth coincident with 

the collecttion of acoustic data at Green Canyon, 19, 

April 3-4, 1995 . 

224 
Dawn ---- Noon 

""""Dusk ------- Midnight 

10 

x 6 

0 

0 

0 4 

2 -- -

10 30 50 70 90 110130150170190210 

Depth (m) 

Appendix 3-12 . Plot of depth with dissolved oxygen 

coincident with acoustic data at Green Canyon 18, 

April 3-4, 1995 

225 
Current Speed 

Dawn (Y1) --- Noon (Y1) 

Dusk (Y1) -~-~-~- Midnight (Y1) i 

Current Directions " Dawn (Y2) + Noon (Y2) ', 

" Dusk (Y2) x Midnight (Y2) 

360 

70 , - ~ -~` - - 

300 n 60 ~ _ ,,-

X 50 - --- ---- X - -

j' 240 

-A 0 40 180 0 CL X 

_--

c 3 INN 120 

U 

COCD 

20 m 

,, O 

10 

0 ; ~- 0 

0 15 35 55 75 95 115 135 155 175 195 

Depth (m) 

Appendix 3-13 . Plot of current speed and direction 

with depth coincident with acoustic data at Green 

Canyon 18, July 11-12, 1995 . 

226 
', Dawn ---- Noon 

Dusk -~-'-'- Midnight 

30 

25 

U 

0 

4 0 ~ 2 ca 

E 

15 

10 '!--T-----~--~ 

0 15 35 55 75 95 115 135 155 175 195 

Depth (m) 

Appendix 3-14 . Plot of temperature and water depth 

coincident with acoustic data at Green Canyon 18, July 

11-12, 1995 . 

227 
Dawn ---- Noon 

Dusk Midnight 

40 

35 

Q 

30 

25 I~- 

20 

0 15 35 55 75 95 11513515517519 

Depth (m) 

Appendix 3-15 . Plot of salinity with depth coincident with 

the collection of acoustic data at Green Canyon 18, July 

11-12, 1995 . 

228 
Dawn ---- Noon 

""""""" Dusk -'----- Midnight 

10 

x 

O 

0 

0 

8'- 

6 

- -ft 4 

2 T_T 

0 15 35 55 75 95 115135155175195 

Depth (m) 

Appendix 3-16 . Plot of depth with dissolved oxygen 

coincident with acoustic data at Green Canyon 18, July 

11-12, 1995 . 

229 
Current Speed 

Current Direction 

70 

60 

E 50 

U 

~ 40 

a 

30 

v 20 

1 

0 

Dawn (Y1) ---- Noon (Y1) 

Dusk (Y1) -~-~-~- Midnight (Y1) 

Dawn (Y2) + Noon (Y2) 

Dusk (Y2) X Midnight (Y2) 

_ 

T 

- __--~- 

` -. -- __ 

-T ~ - 

-- `` -- - 

x

. 

 , ` 

-- - 

" ~-' - 

60 

300 

m 

240 

CD 0 

180 0 

a - 

CD 

`V 

60 

0 

0 15 35 55 75 95 115 135 155 175 195 

Depth (m) 

Appendix 3-17 . Plot of current speed and direction 

with depth coincident with acoustic data at Green 

Canyon 18, November 20, 1995 . 

230 
I Dawn 

', . . . . . . . . . . . . . . Dusk 

30 

25 

U 

0 

L 

20 

L 

15 

---- Noon 

-'-'-'- Midnight 

10 

0 15 35 55 75 95 115 135 155 175 195 

Depth (m) 

Appendix 3-18 . Plot of temperature and water depth 

coincident with acoustic data at Green Canyon 18, 

November 18-20, 1995 . 

231 
Dawn 

. . . . . . . . . . . . . . Dusk 

40 r 

35 

30 

cn 

25 

20~- 

---- Noon 

. . . . . . . Midnight 

0 15 35 55 75 95 115 135 155 175 195 

Depth (m) 

Appendix 3-19 . Plot of salinity with depth coincident with 

the collection of acoustic data at Green Canyon 18, 

November 18-20, 1995 . 

232 
Dawn ---- Noon 

""""""" Dusk -'----- Midnight 

c 

N 

x 6 

O 

a) 

0 

0 4 

2 ~I --

0 15 35 55 75 95 115135155175195 

Depth (m) 

Appendix 3-20 . Plot of depth with dissolved oxygen 

coincident with acoustic data at Green Canyon 18, 

November 18-20, 1995 . 

233 
Current Speed 

Dawn (Y1) 

Dusk (Y1) 

Current Direction " Dawn (Y2) 

" Dusk (Y2) 

70 

---- Noon (Y1) 

-'-'-'- Midnight (Y1) 

+ Noon (Y2) 

Midnight (Y2) 

,,360 

60 

_ ' 300 

-- 

m 

E 50 ~ ~240 

cD 40 - 0 

180 0. 0- 1 4 

.6-0 3 --

L X I 120 L 

20 - - m 

cn 

10 ! !~ , `', ` ~' 6 U 

r 

--

10 30 50 70 90 110 130 150 170 190 

Depth (m) 

Appendix 3-21 . Plot of current speed and direction 

with depth coincident with acoustic data at Green 

Canyon 18, March 4-5, 1996 . 

234 
30 r 

25 

U 

0 

L 

20 

L 

15 

Dawn 

. . . . . . . . . ., . Dusk 

10 

10 30 50 70 90 110 130 150 170 190 210 

Depth (m) 

Appendix 3-22 . Plot of temperature and water depth 

coincident with acoustic data at Green Canyon 18, 

March 4-5, 1996 . 

---- Noon 

-'-'-'- Midnight 

235 
Dawn 

. . . . . . . . . . . . . . Dusk 

40 F---. 

35 

30 

25 

20 : ---; -

Noon 

gni Mid ht 

-- J 

10 30 50 70 90 110 130 150 170 190 210 

Depth (m) 

Appendix 3-23 . Plot of salinity with depth coincident with 

the collection of acoustic data at Green Canyon 18, 

March 4-5, 1996 . 

236 
Dawn - - - - Noon 

Dusk -'-'-'- Midnight 

10~ 

a 

. . 

i 

x 6 1 

O 

a~ " - 

o 

cn 

-_ -- 

o 

2 '~----__ I _--, 

10 30 50 70 90 110130150170190210 

Depth (m) 

Appendix 3-24 . Plot of depth with dissolved oxygen 

coincident with acoustic data at Green Canyon 18, 

March 4-5, 1996 . 

237 
Dawn (Y1) 

Current Speed 

. . . . . . . . . . . . . Dusk (Y1) 

Current Direction " Dawn (Y2) 

" Dusk (Y2) 

70 

i 

---- Noon (Y1) 

Midnight (Y1) 

+ Noon (Y2) 

Midnight (Y2) 

X360 

300 

++ 

E 50~----- 240 

-n 

m 

180 0 

30 -I 

120 cn 

7C `~ _ 20 ; 

60 10 

1,00 

1010 .00 

0, 0 

10 30 50 70 90 110 130 150 170 190 

Depth (m) 

Appendix 3-25 . Plot of current speed and direction 

with depth coincident with acoustic data at Green 

Canyon 18, April 9-10, 1996 . 

238 
Dawn ---- Noon 

Dusk -~-~-~- Midnight 

30 

25 

U 0 

L 

20 

L^' 

W 

W 

15 

10 30 50 70 

--- 

~ -~ 

90 110 130 150 170 190 210 

Depth (m) 

Appendix 3-26 . Plot of temperature and water depth 

coincident with acoustic data at Green Canyon 18, April 

9-10, 1996 . 

239 
Dawn 

. . . . . . . . . . . . . . Dusk 

40 ~ 

---- Noon 

Midnight 

35'i 

a 

30 

cn 

25 

2 0 ~- 

10 30 50 70 90 110 130 150 170 190 210 

Depth (m) 

Appendix 3-27 . Plot of salinity with depth coincident with 

the collection of acoustic data at Green Canyon 18, April 

9-10, 1996 . 

240 
Dawn 

. . . . ., ., . . . . . . Dusk 

10 

x 6 0 

0 

0 4 

2~ 

Noon 

Midnight 

10 30 50 70 90 110130150170190210 

Depth (m) 

Appendix 3-28 . Plot of depth with dissolved oxygen 

coincident with acoustic data at Green Canyon 18, 

April 9-10, 1996 . 

241 
Dawn (Y1) ---- Noon (Y1) 

Current Speed II 

Dusk (Y1) -'-'-'- Midnight (Y1) 

Current Directional " Dawn (Y2) + Noon (Y2) 

" Dusk (Y2) x Midnight (Y2) 

-- 

,360 

70 ~ _ ---- 

60 _ ~ 300 

CIO 

~ 50 ~ - -- ---~~ 240 a 

c540 n 180 0. 

fl- CIO 

1 20 (COD 

Ali 20 CD 

V 60 

i 

0 T I 

0 15 35 55 75 95 115 135 155 175 195 

Depth (m) 

Appendix 3-29 . Plot of current speed and direction 

with depth coincident with acoustic data at Green 

Canyon 18, Auguust 13, 1996 . 

242 
30 

25 ~ 

0 

L 

20 

L^` 

W 

W 

15 

Dawn 

. . . . . . . . . . . . . . Dusk 

10 T --~- 

0 15 35 55 75 95 115 135 155 175 195 

Depth (m) 

Appendix 3-30 . Plot of temperature and water depth 

coincident with acoustic data at Green Canyon 18, 

August 13, 1996 . 

---- Noon 

Midnight 

243 
Dawn 

., . . . . . . . . . . . . Dusk 

--- 

40 F35 

4-0 

II 

>,30 .~ 

25 r i 

---- Noon 

Midnight 

20 

0 15 35 55 75 95 115 135 155 175 195 

Depth (m) 

Appendix 3-31 . Plot of salinity with depth coincident with 

the collection of acoustic data at Green Canyon 18, 

Auugust 13, 1996 . 

244 
Dawn - - - - Noon 

Dusk -'-'-'- Midnight 

10 

g ~~ --- 

x 6 

o 

, . -- --- --- 

o 

2 _-- -T-- - ---- . - 

0 15 35 55 75 95 115135155175195 

Depth (m) 

Appendix 3-32 . Plot of depth with dissolved oxygen 

coincident with acoustic data at Green Canyon 18, 

August 13, 1996 . 

245 
Dawn (Y1) 

Current Speed 

. . . . . . . . . . . Dusk (Y1) 

Current Direction Dawn (Y2) 

" Dusk (Y2) 

l 

70 

60 

E 5 

40 

a 

30 

v 20 

10 

---- Noon (Y1) 

-~-~- Midnight (Y1) 

+ Noon (Y2) 

Midnight (Y2) 

360 

-- - 

X300 

- -- 240 

i 

Aff- CL 

'_-

-1, 180 0 

~ cD 120 

CD 

60 

0 --~ - --- . - , ; 1 1 

10 30 50 70 90 110 130 150 170 190 

Depth (m) 

Appendix 3-33 . Plot of current speed and direction 

with depth coincident with acoustic data at Green 

Canyon 18, November 20, 1996 . 

246 
Dawn 

., . . . . . . . . . . . . Dusk 

30 

25 

.-

U 

0 

CD L 

20 

L 

15 

---- Noon 

-'-'-'- Midnight 

10 ~~ T10 30 50 70 90 110 130 150 170 190 210 

Depth (m) 

Appendix 3-34 . Plot of temperature and water depth 

coincident with acoustic data at Green Canyon 18, 

November 18-20, 1996 . 

247 
i Dawn 

. . . . . . . . . . . . Dusk 

40 

35 

.-. i 

i 

u) 

25 --- 

Noon I 

Midnight 

201 

10 30 50 70 90 110 130 150 170 190 210 

Depth (m) 

Appendix 3-35 . Plot of salinity with depth coincident with 

the collection of acoustic data at Green Canyon 18, 

November 18-20, 1996 . 

248 
Dawn - - - - Noon 

""""""" Dusk ------- Midnight 

10~ 

o-. 8 

x 6 

0 

0 

U) 4 IF 0 

2 

10 30 50 70 90 110130150170190210 

Depth (m) 

Appendix 3-36 . Plot of depth with dissolved oxygen 

coincident with acoustic data at Green Canyon 18, 

November 18-20, 1996 . 

249 
Dawn (Y1) 

Current Speed 

. . . . . . . . . . . Dusk (Y1) 

Current Directionli " Dawn (Y2) 

" Dusk (Y2) 

I ---- 

701 

---- Noon (Y1) 

-~-~-~- Midnight (Y1) 

+ Noon (Y2) 

Midnight (Y2) ' 

360 

300 C) 60 - 

CD 

E 50f~ ,240 

~. 

p 

m 

n 

180 0 

Ca. =3 

---30 - 

0 . . . . . .,, !, 120 c~ 

''60 10 --- 

14>-, '~ -- 

Ct 

~~ t - o 

10 30 50 70 90 110 130 150 170 190 

Depth (m) 

Appendix 3-37 . Plot of current speed and direction 

with depth coincident with acoustic data at Green 

Canyon 18, March 4-5, 1997 (note Dawn data not 

available due to winch failure) . 

250 
Dawn 

I, . . . . . . . . . . . . . . Dusk 

30~ 

25 F 

U 

0 

20 

L 

W 

15 

---- Noon 

Midnight 

J 

. ., 

. , 

10' -r 

10 30 50 70 90 110 130 150 170 190 210 

Depth (m) 

Appendix 3-38 . Plot of temperature and water depth 

coincident with acoustic data at Green Canyon 18, 

March 6-7, 1997 

251 
Dawn ---- Noon 

Dusk -----'- Midnight 

40 

35 

.~ 30 

25 

20 

90 110 130 150 

Depth (m) 

170 190 210 

Appendix 3-39 . Plot of salinity with depth coincident with 

the collection of acoustic data at Green Canyon 18, 

March 6-7, 1997 . 

252 

10 30 50 70 
NT Op Tjr~'y~ The Department of the Interior Mission 

a - p As the Nation's principal conservation agency, the Department of the Interior has responsibility fur 

a most of our nationally owned public lands and natural resources. This includes fostering sound use 

of our land and water resources; protecting our fish, wildlife, and biological diversity; preserving the 

_ 9 environmental and cultural values of our national parks and historical places; and providing for the 

~4RCH 3 enjoyment of life through outdoor recreation . The Department assesses our energy and mineral 

resources and works to ensure that their development is in the best interests of all our people by 

encouraging stewardship and citizen participation in their care. The Department also has a major 

responsibility for American Indian reservation communities and for people who live in island territories 

under U.S . administration . 

The Minerals Management Service Mission 

~~.xr or Tyc 

~~ As a bureau of the Department of the Interior, the Minerals Management Service's (MMS) primary 

I~~~'/- ~ \'?`~`-~ responsibilities are to manage the mineral resources located on the Nation's Outer Continental Shelf 

,( (OCS), collect revenue from the Federal OCS and onshore Federal and Indian lands, and distribute 

those revenues . 

Moreover, in working to meet its responsibilities, the Offshore Minerals Management Program 

administers the OCS competitive leasing program and oversees the safe and environmentally sound 

exploration and production of our Nation's offshore natural gas, oil and other mineral resources . The 

DIMS Royalty Management Program meets its responsibilities by ensuring the efficient, timely and 

accurate collection and disbursement of revenue from mineral leasing and production due to Indian 

tribes and allottees, States and the U.S . Treasury . 

The MMS strives to fulfill its responsibilities through the general guiding principles of : (1) being 

responsive to the public's concerns and interests by maintaining a dialogue with all potentially affected 

parties and (2) carrying out its programs with an emphasis on working to enhance the quality of life for 

all Americans by lending MMS assistance and expertise to economic development and environmental 

protection .