Milton S. Love,

Donna H. Shroeder, and Mary H. Hishimot.o

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CONTENTS

Executive Summary v

Chapter 1 1-1

Introduction

Chapter 2 2-1

A Brief History of Oil Development in Southern California

Chapter 3 3-1

A Review of Biological and Oceanographic Surveys: Results and Analyses

Chapter 4 4-1

A Guide to Ecological and Political Issues Surrounding Oil Platform Decommissioning in California

Chapter 5 5-1

Research and Monitoring Recommendations

Acknowledgements and Personal Communications 5-3

References R-1

Tables T-1

Appendices

Appendix 1 A-1

Appendix 2 A-11

Appendix 3 A-13

Appendix 4 A-29

Mexican rockfish at bottom of Platform Gail. 

LINDA SNOOK

OCS Study MMS 2003-032

Milton S. Love

Donna M. Schroeder

Mary M. Nishimoto

Marine Science Institute

University of California

Santa Barbara, CA, 93106

email address (for M. Love): love@lifesci.ucsb.edu

www.id.ucsb.edu/lovelab

June 2003

Prepared under Cooperative Agreement #1445-CA09-

95-0836 between the Biological Resources Division, U. S. 

Geological Survey, and the Marine Science Institute, University of California, Santa Barbara, in cooperation with 

the Minerals Management Service, Pacific OCS Region.

Front Cover: Background, young-of-the-year rockfishes, 

Platform Grace (Mary Nishimoto). From upper left: 

Seastars and mussels, midwater, Platform Holly (Dan 

Dugan); Platform Irene (Linda Snook); juvenile bocaccio, 

midwater, Platform Gilda (Donna Schroeder); young-ofthe-year yellowtail rockfish, Platform Irene (Rick Starr); 

flag rockfish, Platform Grace (Donna Schroeder); youngof-the-year cowcod, shell mound, Platform Gail (Milton 

Love); juvenile vermilion rockfish, bottom, Platform 

Grace (Donna Schroeder). 

Back Cover: Kelp rockfish and club anemones, midwater, 

Platform Holly (Dan Dugan). 

Project Cooperation

This research addressed an information need identified by the U. S. Department of the Interior’s Minerals 

Management Service, Pacific OCS Region, Camarillo, 

California.

Disclaimer

This research was conducted under a cooperative agreement (Agreement 1445-CA09-95-0836) between the U. S. 

Geological Survey (Biological Resources Division) and the 

University of California, Santa Barbara. This report was reviewed and approved for publication by the BRD. Approval 

does not signify that the contents necessarily reflect the views 

and policies of the BRD or MMS, nor does mention of trade 

names or commercial products constitute endorsement or 

recommendation for use.

Report Availability

Available for viewing and in PDF at: 

www.id.ucsb.edu/lovelab

Reprints available at:

Milton Love

Marine Science Institute

University of California, Santa Barbara

Santa Barbara, CA 93106

(805) 893-2935

Lyman Thorsteinson

Western Fisheries Research Center

U. S. Geological Survey

6505 NE 65th St.

Seattle, Washington 98115

(206) 526-6569

Minerals Management Service 

Pacific OCS Region

770 Paseo Camarillo

Camarillo, CA 99010

(805) 389-7800

Suggested Citation

Love, M. S., D. M. Schroeder, and M. M. Nishimoto. 2003. 

The ecological role of oil and gas production platforms 

and natural outcrops on fishes in southern and central 

California: a synthesis of information. U. S. Department 

of the Interior, U. S. Geological Survey, Biological Resources Division, Seattle, Washington, 98104, OCS Study 

MMS 2003-032.

The Ecological Role of Oil and Gas Production Platforms and Natural Outcrops on Fishes in 

Southern and Central California: A Synthesis of Information
v

EXECUTIVE SUMMARY

Opposite: Juvenile widow rockfish in platform midwater. (Photograph by Lovelab, UC Santa Barbara)

Information Needed

Production of oil and gas from offshore platforms 

has been a continual activity along the California coast 

since 1958. There are 26 oil and gas platforms off California, 23 in federal waters (greater than 3 miles from shore) 

and 3 in state waters. The platforms are located between 

1.2 to 10.5 miles from shore and at depths ranging from 

11 to 363 m (35–1,198 ft.). Crossbeams and diagonal 

beams occur about every 30 m (100 ft.), from near the 

surface to the seafloor. The beams extend both around 

the perimeter of the jacket and reach inside and across 

the platform. The beams and vertical pilings (forming the 

jacket) and the conductors on all platforms are very heavily encrusted with invertebrates and provide important 

habitat for fishes. The seafloor surrounding a platform 

is littered with mussel shells. This “shell mound” (also 

called “mussel mound” or “shell hash”) is created when 

living mussels, and other invertebrates, are dislodged and 

fall to the seafloor during platform cleaning or storms. 

Once an industrial decision is made to cease oil and 

gas production, managers must decide what to do with 

the structure, a process known as decommissioning. Platform decommissioning can take a number of forms, from 

leaving much, or all, of the structure in place to complete 

removal. Along with the platform operator, many federal 

and state agencies are involved in the decommissioning 

process. All oil and gas platforms have finite economic 

lives and by the beginning of the twenty-first century, 

seven platforms in southern California had been decommissioned and a number of others appeared to be nearing 

the end of their economic lives. 

Management decisions regarding the decommissioning of an oil and gas platform are based on both 

biological and socioeconomic information. This study 

addressed the need for resource information and better 

understanding of how offshore oil/gas platforms contributed to the fish populations and fishery productivity 

in the Santa Maria Basin and Santa Barbara Channel. 

Prior to our studies, there was almost no biological information on Pacific Coast platform fish assemblages. 

This necessary research involved broad scale sampling at 

numerous oil/gas platforms and natural reefs. Research 

objectives included 1) characterizing the fish assemblages 

around platforms and natural reefs, 2) examining how 

oceanography affects patterns of recruitment and community structure of reef fishes, and 3) describing the 

spatial and temporal patterns of fish diversity, abundance 

and size distribution among habitat types (e. g., platforms 

and natural outcrops).

Research Summary

Between 1995 and 2001, we studied oil and gas platforms sited over a wide range of bottom depths, ranging 

between 29 and 224 m (95 and 739 ft.) and sited from 

north of Point Arguello, central California to off Long 

Beach, southern California. However, most of the platform research occurred in the Santa Barbara Channel and 

Santa Maria Basin. The Santa Barbara Channel and Santa 

Maria Basin are situated in a dynamic marine transition 

zone between the regional flow patterns of central and 

southern California. The Santa Barbara Channel is about 

100 km long by about 50 km wide (60 x 20 miles) and is 

bordered on the south by the Northern Channel Islands 

(San Miguel, Santa Rosa, Santa Cruz, and Anacapa). This 

area is bathed in a complex hydrographic system of currents and water masses. Generally, cool coastal waters 

from the California Current enter the Santa Barbara 

Channel through its west entrance at Point Conception. 

Warm waters from the Southern California Bight flow 

in the opposite direction into the channel through its 

eastern entrance. Surface waters are substantially warmer 

in the Bight than north of Point Conception due to less 

wind-induced vertical mixing, the solar heating of surface 

waters, and currents of subtropical waters entering from 

the south. The convergence of different water masses in 

the Santa Barbara Channel results in relatively large scale 

differences in physical parameters (e.g., temperature, salinity, oxygen, and nutrient concentrations) and biotic 

assemblages (e. g., flora and fauna).

Scuba surveys were conducted at shallow depths 

and submersible surveys, using the research submarine 

Delta, at greater depths. We also surveyed shallow-water 

and deeper-water rock outcrops, many in the vicinity of 

platforms. Nine nearshore, shallow-water rock outcrops, 

seven on the mainland and two at Anacapa Island, were 

monitored annually from 1995 to 2000. These natural 

outcrops are geographically distributed across the Santa 

Barbara Channel providing opportunities for spatial 

comparisons. In addition, we surveyed over 80 deeperwater outcrops, in waters between 30 and 360 m (100 
vi

EXECUTIVE SUMMARY

vii

EXECUTIVE SUMMARY

and 1,180 ft.) deep, located throughout the Southern 

California Bight and off Points Conception and Arguello. 

These sites included a wide range of such habitats as 

banks, ridges, and carbonate reefs, ranging in size from 

a few kilometers in length to less than a hectare in area.

On these features, we focussed on hard bottom macrohabitats, including kelp beds, boulder and cobble fields, 

and bedrock outcrops. Most of these deeper-water sites 

were visited once, a few were surveyed during as many 

as four years and one outcrop, North Reef, near Platform 

Hidalgo, was sampled annually.

Most of our oil and gas platform surveys were 

conducted at nine structures (Platforms Irene, Hidalgo, 

Harvest, Hermosa, Holly, Gilda, Grace, Gina, and Gail)

located in the Santa Barbara Channel and Santa Maria 

Basin. Between 1995 and 2000, we conducted annual 

surveys on the shallow portions of these nine platforms. 

The shallowest of the nine platforms, Gina, was surveyed 

from surface to bottom depths using scuba techniques. 

Deep-water surveys conducted between 1995 and 2001, 

using the research submersible, Delta, studied the same 

platforms excluding the bottom of Gilda and all of Gina. 

In 1998, one submersible survey was conducted around 

Platform Edith, located off Long Beach. In 2000 partial 

submersible surveys were completed around Platforms C, 

B, A, Hillhouse, Henry, Houchin, Hogan, and Habitat.

Patterns in Shallow-Water Habitats

Regional and local processes influenced patterns of 

outcrop fish assemblages in shallow waters. At regional 

spatial scales, outcrop fish abundance patterns often 

shifted abruptly as oceanographic patterns changed, 

roughly defining a cool-temperate assemblage in the 

western Santa Barbara Channel, and a warm-temperate 

assemblage in the eastern Santa Barbara Channel. This 

distinctive spatial pattern was observed in both oil and 

gas platform and natural outcrop habitats. In shallow 

waters, there was greater variability in platform species 

assemblages and population dynamics compared to natural outcrop assemblages, and this was most likely caused 

by the greater sensitivity of platform habitats to changing 

oceanographic conditions. Local processes that affected 

fish distribution and abundance were related to habitat 

features, where depth, relief height, and presence of giant 

kelp all played important roles. On platform habitat, we 

found that the majority of newly settled rockfish juveniles 

resided at depths greater than 26 m (86 ft.), although 

there were differences among species.

Characterization of the Deepwater 

Platform Fish Assemblages

With the exception of the shallow-water Platform 

Gina, all of the platforms we surveyed were characterized 

by three distinct fish assemblages: midwater, bottom, and 

shell mound. Rockfishes, totaling 42 species, dominated 

these habitats. Fish densities at most platforms were highest in the midwater habitat reflecting the depth preferences of young-of-the-year rockfishes. Young-of-the-year 

rockfishes represented the most abundant size classes in 

platform midwaters. Platform midwaters were nursery 

grounds for rockfishes as well as for a few other species, 

including cabezon and painted greenling. The youngof-the-year of at least 16 rockfish species inhabited these 

waters. Settlement success was affected by oceanographic 

conditions. Densities of young-of-the-year varied greatly 

between years and platforms. Young-of-the-year rockfish 

densities often varied by an order of magnitude or greater 

among survey years and platforms. From 1996 through 

1998, rockfish settlement was generally higher around 

the platforms north of Point Conception as compared to 

platforms in the Santa Barbara Channel. This finding is 

reflective of the generally colder, more biologically productive waters in central California during the 1980s and 

much of the 1990s. Colder waters in 1999 were associated 

with relatively high levels of rockfish recruitment at all 

platforms surveyed. In 2000 and 2001, juvenile rockfish 

recruitment at platforms in the Santa Barbara Channel 

remained higher than pre-1999 levels, possibly reflecting 

the oceanographic regime shift to cooler temperatures 

that may be occurring in southern California. 

Subadult and adult rockfishes and several other species dominated the bottom habitats of platforms. The 

bottom habitat of some platforms is also important nursery habitat as, in some instances, young-of-the-year rockfishes were observed in very large numbers. In general, 

more than 90% of all the fishes around platform bottoms 

were rockfishes. Bottom depth strongly influenced the 

number of species, species diversity, and density of fishes 

living around platform bases. This is distinctly different 

than the pattern observed in platform midwaters. The 

platform base provides habitat for not only fishes but 

also their prey and predators.

Shell mounds supported a rich and diverse fish 

assemblage. As at other platform habitats, rockfishes 

comprised the vast majority of the fishes. The many 

small sheltering sites created by mussels, anemones, and 

other invertebrates on the shell mounds created a habitat 

occupied by small fishes. Many of these fishes were the 

young-of-the-year and older juveniles of such species as 

lingcod and copper, flag, greenblotched, and pinkrose 

rockfishes and cowcod. The adults of these species also 

inhabited the platform bottom.

Platform versus Reef Fish Assemblages

We compared the species composition of the fish 

assemblages at Platform Hidalgo and at North Reef, 

an outcrop located about 1,000 m (3,300 ft.) from the 

platform. The assemblages were quite similar, both were 

dominated by rockfishes. In general, the distinctions between the platform and outcrop assemblages were based 

on differences in species densities, rather than species’ 

presence or absence. Most species were more abundant 

at Platform Hidalgo. Halfbanded, greenspotted, flag, 

greenstriped, and canary rockfishes, and all three life 

stages of lingcod (young-of-the-year, immature, adult) 

and painted greenling had higher densities around the 

platform. Five species (pink seaperch, shortspine combfish, pygmy, squarespot, and yellowtail rockfishes) were 

more abundant at the outcrop. Young-of-the-year rockfishes were found at both Platform Hidalgo (primarily 

in the midwaters) and at North Reef. Young-of-the-year 

rockfish densities were higher at the platform than at 

the outcrop in each of the five years studied. In several 

years, their densities were more than 100 times greater 

at Platform Hidalgo compared to North Reef.

Rockfishes numerically dominated the fish assemblages at almost all of the platform and hard seafloor 

habitats in our study. Overall species richness was greater 

at the natural outcrops (94) than at the platforms (85). 

There was a high degree of overlap in species between 

platforms and outcrops and differences were primarily 

due to generally higher densities, of more species, at platforms. In general, canary, copper, flag, greenblotched, 

greenspotted, greenstriped, halfbanded, vermilion rockfishes, bocaccio, cowcod, and widow rockfish young-ofthe-year, painted greenling and all life history stages of 

lingcod were more abundant at platforms than at all or 

most of the outcrops studied. Yellowtail rockfish and the 

dwarf species pygmy, squarespot, and swordspine rockfishes were more abundant on natural outcrops.

Findings

Our research demonstrates that some platforms may 

be important to regional fish production. The higher 

densities of rockfishes and lingcod at platforms compared 

to natural outcrops, particularly of larger fishes, support 

the hypothesis that platforms act as de facto marine refuges. High fishing pressure on most rocky outcrops in 

central and southern California has led to many habitats 

almost devoid of large fishes. Fishing pressure around 

most platforms has been minimal. In some locations, 

platforms may provide much or all of the adult fishes of 

some heavily fished species and thus contribute disproportionately to those species’ larval production. 

Platforms usually harbored higher densities of youngof-the-year rockfishes than natural outcrops and thus may

be functionally more important as nurseries. Platforms 

may be more optimal habitat for juvenile fishes for several 

reasons. First, because as structure they physically occupy 

more of the water column than do most natural outcrops; 

presettlement juvenile or larval fishes, transported in the 

midwater, are more likely to encounter these tall structures 

than the relatively low-lying natural rock outcrops. Second, 

because there are few large fishes in the midwater habitat, 

predation on young fishes is probably lower. Third, the 

offshore position and extreme height of platforms may 

provide greater delivery rates of planktonic food for young 

fishes. Most of the natural outcrops we found that had high 

densities of young-of-the-year rockfishes were similar to 

platforms as they were very high relief structures that thrust 

their way well into the water column. 

Our research, and reviews of existing literature, 

strongly implies that platforms, like natural outcrops, 

both produce and attract fishes, depending on species, 

site, season, and ocean conditions. Platform fish assemblages around many of the deeper and more offshore 

platforms probably reflect recruitment of larval and pelagic juvenile fishes from both near and distant maternal 

sources, not from attraction of juvenile or adult fishes 

from natural outcrops. Annual tracking observations of 

strong year classes of both flag rockfish and bocaccio 

imply that fishes may live their entire benthic lives around 

a single platform. A pilot study showed that young-ofthe-year blue rockfish grew faster at a platform than at a 

natural outcrop indicating that juvenile fishes at platforms 

are at least as healthy as those around natural outcrops.

Management Applications

In this report, we discuss the ecological and political issues that surround platform decommissioning in California, 

including the ecological consequences of the four platform 

decommissioning alternatives: (1) Complete Removal, 

(2) Partial Removal and Toppling, and (3) Leave-in-Place.

Complete Removal: In complete removal, operators 

may haul the platform to shore (for recycling, reuse, or 

disposal) or it can be towed to another site and reefed. 
viii

EXECUTIVE SUMMARY

ix

EXECUTIVE SUMMARY

A typical full-removal project begins with well abandonment in which the well bores are filled with cement. The 

topsides, which contain the crew quarters and the oil and 

gas processing equipment, are cut from the jacket and removed and the conductors are removed with explosives.

Finally, the piles that hold the jacket to the seabed are 

severed with explosives and the jacket is removed. 

Completely removing a platform for disposal on land 

will kill all attached invertebrates. If some of the platform 

structure is hauled to a reef area and replaced in the water, 

some of these animals may survive, depending on water 

depth and the length of time the structure is exposed to 

the air. The explosives used to separate the conductor and 

jacket from the seafloor kill large numbers of fishes. In a 

study in the Gulf of Mexico, explosives were placed 5 m 

(15 ft.) below the seafloor to sever the well conductors, 

platform anchor pilings and support legs, of a platform 

in about 30 m (100 ft.) of water. All of the fishes on or 

near the bottom and most of the adult fishes around 

the entire platform suffered lethal concussions. Marine 

mammals and sea turtles may also be indirectly killed by 

damage to the auditory system. 

The use of explosives to remove or topple a platform 

may also complicate fishery-rebuilding programs. Cowcod, a species declared overfished by NOAA Fisheries, 

provides an example. This species is the subject of a federal rebuilding plan that severely limits catches. In 2001, 

this was 2.4 metric tons or about 600 fish. Based on our 

research, there are at least 75 adult cowcod on Platform 

Gail. If explosives are used to remove Gail, all of these fish 

will be killed. The loss of at least 75 adult cowcod may be 

sufficiently large to complicate the rebuilding plan. 

Partial Removal and Toppling: Under both partial 

removal and toppling the topsides are removed. In partial removal, the jacket is severed to a predetermined 

depth below the surface and the remaining subsurface 

structure is left standing. In toppling, the conductors 

and piles are severed with explosives and the jacket is 

pulled over and allowed to settle to the seafloor. In both 

partial removal and toppling, conductors need not be 

completely removed. Retaining conductors would add 

habitat complexity to a reefed platform.

While the immediate mortality impact to attached 

invertebrates of partial removal is greater than leaving the 

platform structure in place, mortality risks to both fishes 

and invertebrates are much lower than in both toppling 

and total removal. Partial removal causes fewer deaths 

than does toppling for two reasons. First, because partial 

removal does not require explosives (as does toppling), 

there is relatively little fish, marine mammal, sea turtle, 

and motile invertebrate (such as crab) mortality. In addition, when a platform is partially removed, vertebrate and 

invertebrate assemblages associated with the remaining 

structure are likely to be minimally affected. In contrast, 

when a platform is toppled, the jacket falls to the seafloor, 

and, depending on bottom depth, many, if not most of 

the attached invertebrates die.

Both partial removal and toppling would produce 

reefs with somewhat different fish assemblages than those 

around intact platforms. With the shallower parts of the 

platform gone, it is likely that partial removal would result 

in fewer nearshore reef fishes, such as seaperches, basses, 

and damselfishes. However, young-of-the-year rockfishes 

of many species recruit in large numbers to natural outcrops that have crests in about 30 m (100 ft.) of water or 

deeper. Thus, it is possible that partial removal would result 

in little or no reduction in young-of-the-year recruitment 

for many rockfish species. The pelagic stage of some rockfish species, particularly copper, gopher, black-and-yellow 

and kelp, may recruit only to the shallowest portions of 

the platform. For these species, both partial removal and 

toppling would probably decrease juvenile recruitment, 

depending on the uppermost depth of the remaining 

structure. Young-of-the-year rockfishes, which make up 

the bulk of the fish populations in the platform midwater habitat, would probably be less abundant around a 

toppled platform compared to a partially removed one. 

Because most California platforms reside in fairly deep 

water, toppled platforms might reside at depths below 

much rockfish juvenile settlement. Thus, toppling might 

result in lowered species composition and fish density. 

However, depending on the characteristics of the platform, 

a toppled structure, with twisted and deformed pilings and 

beams, might have more benthic complexity than one that 

is partially removed. This might increase the number of 

such crevice dwelling fishes as pygmy rockfishes.

It is difficult to catch fishes that live inside the vertically standing platform jacket. Our observations demonstrate that many of the rockfishes living at the platform 

bottom, such as cowcod, bocaccio, flag, greenspotted, and 

greenblotched rockfishes, dwell in the crevices formed 

by the bottom-most crossbeam and the seafloor. To a 

certain extent, these fishes are protected from fishing 

gear by the vertical mass of the platform, a safeguard 

that would persist if the platform were partially removed, 

particularly if the conductors remained in place. It would 

be much easier to fish over a toppled platform, as more 

of the substrate would be exposed to fishing gear. 

Coast Guard regulations do not require a minimum 

depth below the ocean surface to which a decommissioned platform must be reduced. The decision on how 

much of the jacket and conductors is left in place is based 

on both a Coast Guard assessment and the willingness 

of the liability holder to pay for the navigational aids 

required by the Coast Guard. As mussels become rare 

below about 30 m (100 ft.) on most platforms, the mistaken assumption that all partially removed platforms 

must be cut to 24–30 m (80–100 ft.) below the surface 

has led some to conclude that this will inevitably lead to 

a severe reduction in the amount of mussels that fall to 

the bottom and, thus, to a change in or end to, the shell 

mound community. This is not necessarily the case. 

Leave-in-Place: A platform could be left in its 

original location at the time of decommissioning. The

topsides would be stripped of oil and gas processing 

equipment, cleaned, and navigational aids installed. If 

a platform were left in place, the effect on platform sea 

life would be minimal. 

Pacific Coast Platforms

In this report we have also included a brief summary of 

information on all of the Pacific Coast platforms (Appendix 

1), densities of all fishes observed at each platform during 

scuba and submersible surveys (Appendix 2 and Appendix 

3, respectively), and a list of the 20 most important sites, 

both platforms and natural outcrops, for the most abundant species in our deepwater study (Appendix 4). 

Research Needs

Our research demonstrates that additional biological 

information is needed in the decommissioning process. 

These information needs fall into three categories: (1) 

A comparison of the ecological performance of fishes 

living at oil platforms and on natural outcrops, (2) A 

definition of the spatial distribution of economically 

important species (of all life history stages) within the 

region of interest and a definition of the connectivity of 

habitats within this region, and (3) An understanding of 

how habitat modification of the platform environment 

(e.g., removal of upper portion or addition of bottom 

structure) changes associated assemblages of marine life 

Whitespeckled rockfish and white anemones (Metridium at offshore platforms. sp.). MARY NISHIMOTO
x

EXECUTIVE SUMMARY

1-1

Chapter 1

INTRODUCTION

Milton S. Love, Donna M. Schroeder, and Mary M. Nishimoto

Major questions remaining to be addressed include:

What Fishes Live Around Platforms and Nearby 

Natural Reefs?

In order to assess the relative importance of a platform to its region, it is essential to conduct basic surveys 

not only around the platform, but also at nearby reefs. A 

majority of platforms have not been surveyed.

How Does Fish Production around Platforms 

Compare to that at Natural Outcrops? 

It is possible to compare fish production between 

habitats by examining (1) fish growth rates, (2) mortality rates, and (3) reproductive output. A pilot study 

compared the growth rates of young-of-the-year blue 

rockfish at Platform Gilda and Naples Reef and another 

examining young-of-the-year mortality rates is planned. 

Additional work is needed to determine larval dispersal 

patterns and differences in densities at various study sites. 

For example, we now have enough data to study the relative larval production per hectare of cowcod and bocaccio 

at Platform Gail versus that on natural outcrops. 

What Is the Relative Contribution of Platforms in 

Supplying Hard Substrate and Fishes to the Region? 

This research would put in perspective the relative 

contribution of platforms in supplying hard substrate 

and reef fishes to their environment. 

First, this requires knowledge of the rocky outcrops 

in the vicinity of each platform; this is derived from seafloor mapping. Once the mapping is complete, visual 

surveys of the outcrops, using a research submersible, will 

determine the fish assemblages and species densities in 

these habitats. Knowing the areal extent of both natural 

and platforms habitats and the densities of each species 

in both of these habitats, it is then possible to assess the 

total contribution of each platform to the fish populations and hard substrate in that region.

How Long Do Fishes Reside at Oil/Gas Offshore 

Platforms? 

It is unclear how long fishes are resident to platforms. For instance, does the large number of fishes, 

has conducted research on the fishes that live around 

the platforms and on natural rock outcrops. Our goals 

have been to determine the patterns of fish assemblages 

around both platforms and outcrops and to identify the 

processes that may have generated these patterns. In addition, we are attempting to understand the linkages between habitats among different fish life history stages.

Previous Research

Decommissioning decisions in California will 

have a biological as well as socioeconomic and cultural 

component. Therefore, it is timely to summarize what 

is known about the biology and ecology of the fauna 

of these structures. Our emphasis has been on the fish 

assemblages.

Our research on platforms and outcrops occurred 

between 1995 and 2001. Before our research began, only 

a few fish surveys had been conducted around California platforms. Most of this work was conducted around 

platforms Hilda and Hazel, two shallow-water platforms 

off Summerland, just below Santa Barbara (Carlisle et al. 

1964; Allen and Moore 1976; Bascom et al. 1976). Both 

of these structures were removed in 1996. Carlisle et al. 

(1964) found an average of about 6,000 fish under each 

platform. Allen and Moore (1976) estimated an average of 

about 20,000 fishes, occasionally reaching at least 30,000. 

Rockfishes, particularly young-of-the-year fishes, and sea 

perches dominated the assemblages, kelp and barred sand 

bass were also abundant. Large numbers of young bocaccio and widow rockfish living around platforms A, B, and 

C in the Santa Barbara Channel were tagged by the California Department of Fish and Game (Hartmann 1987). 

Six bocaccio were recovered as adults. All had traveled to 

natural outcrops, one 148 km (94 miles) away from the 

platforms. Love and Westphal (1990) compared fishes 

captured around oil platforms and at two nearby natural 

outcrops in the Santa Barbara Channel. Rockfishes were 

the most commonly taken species. Young rockfishes were 

most abundant at the platforms, rockfishes on natural 

outcrops tended to be older. A pilot survey of fishes, 

using a remotely operated vehicle at Platform Hidalgo 

and nearby natural outcrops (Love et al. 1994), identified 

large numbers of young rockfishes at the platform and 

few at natural outcrops. Benthic rockfishes were more 

abundant at natural outcrops.

Goals and Objectives

Production of oil and gas from offshore platforms 

has been a continual activity along the California coast 

since 1958. All oil and gas platforms have finite economic lives and at the beginning of the twenty-first 

century, seven platforms in southern California have 

been decommissioned and a number of others appear 

to be nearing the end of their economic lives. 

Once an industrial decision is made to cease oil 

and gas production, managers must decide what to do 

with the structure, a process known as decommissioning. 

Platform decommissioning can take a number of forms, 

from leaving much, or all, of the structure in place to 

complete removal (see Chapter 4, page 4-1). Along with 

the corporation that owns the platform, federal agencies 

that are involved in the decommissioning process include 

the Minerals Management Service (for Outer Continental Shelf platforms), U. S. Coast Guard, U. S. Army Corps 

of Engineers, National Marine Fisheries Service, U. S. 

Environmental Protection Agency, U. S. Occupational 

Safety & Health Administration. California State agencies include the California State Lands Commission 

(for platforms in State waters), California Regional 

Water Quality Control Districts (for platforms in State 

waters), California Coastal Commission, and California 

Fish and Game Commission. At the local level the County 

Air Pollution Control Districts and agencies such as the 

County Energy Division would also play a role.

Off California, three platforms, Harry (in 1974), 

Helen (in 1978), and Herman (in 1978) were decommissioned through complete removal without a great 

deal of controversy. Public debate arose over decommissioning of platforms Hilda, Hazel, Hope, and Heidi 

when a recreational angler’s group, desiring to continue 

fishing on these structures, began to lobby for their retention. Ultimately, the four platforms were removed in 

1996. It appears certain that future decommissioning 

of California platforms will be controversial because of 

conflicting desires regarding the fate of platforms on 

the part of various marine stakeholders (see Chapter 4, 

page 4-1).

Since 1995, our group, first funded by the Biological Resources Division of the U. S. Geological Survey, 

the Minerals Management Service and most recently by 

the California Artificial Reef Enhancement Program, 

particularly such species as the overfished bocaccio and 

cowcod, remain around the platforms for extended periods? Knowledge of the residence time of these species 

would allow us to more accurately determine if platforms 

form optimal habitat for these species. 

What are the Effects of Platform Retention or 

Removal on Fish Populations within a Region? 

As an example, what effect would platform retention 

or removal have on young-of-the-year fish recruitment? 

Would the young rockfishes that settle out at a platform 

survive in the absence of that platform? Our surveys demonstrate that planktonic juvenile fishes, particularly rockfishes, often settle to platforms in substantial numbers. 

If that platform did not exist, would these young fishes 

have been transported to natural outcrops? Knowing how 

long it would take rockfish larvae to reach suitable natural 

outcrops, and what percent of these larvae would likely 

die before reaching these outcrops, will give a sense of the 

importance of a platform as a nursery ground.

Similarly, using a synthesis of oceanographic information, it is possible to model the fate of larvae produced 

by fishes living at a platform.

How Does Habitat Modification of the Platform 

Environment (e.g., Removal of Upper Portion or 

Addition of Bottom Structure) Change Associated 

Assemblages of Marine Life?

All decommissioning options except leave-in-place 

involve modification of the current physical structure of 

offshore platforms. Is it possible to increase fish diversity 

and density by altering the seafloor or the platform itself? 

For instance, it would be useful to add complexity, in 

the form of quarry rock or other structure, to the shell 

mound around a platform, and follow the changes in 

fish assemblages.

Descriptive information such as depth distribution 

and life history information is also useful in determining 

how decommissioning options affect the environment. 

Experimental research, using a BACI design or similar approach, can aid in predicting how the biotic community 

will respond to such structural changes.
I

1-2

INTRODUCTION

1-3

INTRODUCTION

and fishes. All of the platforms we studied have a crossbeam 

on the seafloor, although portions of the beam may be 

either buried in sediment or undercut by currents.

The seafloor surrounding a platform is littered with 

mussel shells. This “shell mound” (also called “mussel 

mound” or “shell hash”) is created when living mussels, 

and other invertebrates, are dislodged during platform 

cleaning or storms. We observed shell mounds under 

and around all of the platforms we surveyed. Only a few 

of the more shallow shell mounds (around platforms 

Gina, Grace, Henry, and Houchin) have been accurately 

mapped (Sea Surveyor Inc. 2003). These mounds ranged 

from 4–6 m (13–19 ft.) high and were either oval or 

round in shape. Dimensions of these four mounds were: 

Gina, oval, 45 x 64 m (150 x 210 ft.); Grace, oval, 61 x 

118 m (200 x 390 ft.); Henry, round, 76 m (250 ft.) in 

diameter; Houchin, round, 85 m (280 ft.) in diameter. 

Current patterns, rate of shell deposition, and age of 

platform all play a role in the size of shell mounds. 

Rock Outcrops

An objective of our research was to compare fish assemblages and fish productivity at platforms and natural 

outcrops in central and southern California. UnderstandOur current research began in 1995, preliminary 

data is found in Love et al. (1999, 2000, 2001) and 

Schroeder et al. (1999) and we have incorporated that 

information into this report.

Study Area

Platforms

There are 26 oil and gas platforms off California, 23 in 

federal waters (greater than 3 miles from shore) and 3 in state 

waters (Figures 1.1a, b, and c). The platforms are located 

between 1.2 to 10.5 miles from shore and at depths ranging 

from 11 to 363 m (35–1,198 ft.). Information regarding 

location, depth, and other physical features of California’s 

offshore platforms are described in Appendix 1. 

All California platforms are similar in design (Figure 1.2); they primarily vary in size. The above-water 

structures, including oil and gas processing equipment 

and crew living and working quarters are termed the 

topside (also topside facilities and deck). The vertical 

pipes that carry the oil and gas are the conductors. The 

parts of the structure that are embedded in the bottom 

and protrude through the surface to support the topside 

structural components form the jacket that includes the 

crossbeams, legs, and the piles inside the legs. In general, 

the jackets of California platforms are made of carbon 

steel and the topsides are composed of steel plate and 

other structural steel components. Platforms also contain 

a relatively small amount of cement. 

Crossbeams and diagonal beams occur about every 

30 m (100 ft.), from near the surface to the seafloor. The 

beams extend both around the perimeter of the jacket and 

reach inside and across the platform. This web work of cross 

beams provides a great deal of habitat for both invertebrates 

ing spatial variability and trends in fish populations at 

these sites is important as it aids in understanding the 

regional importance of platforms as fish habitat. These 

sites included a wide range of such mesohabitats as banks, 

ridges, and carbonate buildups, ranging in size from a 

few kilometers in length to less than a hectare in area.On 

these features, we focussed on hard bottom macrohabitats, including kelp beds, boulder and cobble fields, and 

bedrock outcrops following standard, statistically based 

sampling methods and techniques.

Physical Oceanography and Biogeography 

of the Platform Study Area

General Description

The study area includes the Santa Barbara Channel 

and Santa Maria Basin (Figure 1.1). These oceanographic 

bodies are situated in a dynamic marine transition zone 

between the regional flow patterns of central and southern 

California. The Santa Barbara Channel is about 100 km 

long by about 50 km wide (60 x 20 miles) and is bordered 

on the south by the Northern Channel Islands (San Miguel, 

Santa Rosa, Santa Cruz, and Anacapa). Within the Santa 

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Figure 1.1. Location of oil and gas platforms off central and southern California. 

Figures 1.1a and 1.1c indicate platforms 

surveyed at least once or at least partially 

by research submersible (stars). Figure 

1-1b indicates platforms (triangles) and 

natural outcrops (diamonds) surveyed 

by scuba. Depths of platforms surveyed 

are also included.

Figure 1.2. A typical oil/gas platform off southern California. Adapted from Manago and Williamson (1998).

Figure 1.3. Satellite image of sea surface temperature (SST) 

and a diagram of the large-scale current patterns off the 

central and southern California coast. This image shows the 

predominant, large-scale SST pattern along with smaller 

scale features such as eddies and fronts (temperature scale, 

degrees Celsius). The generalized flow of the California 

Current (CC), the Inshore Countercurrent (IC), and Southern California Eddy (SCE) overlay the SST image. Plumes 

of cold, nutrient-rich, upwelled water (represented by dark 

blue and purple) originate near the coast and are directed 

offshore (magenta arrows).
1-4

INTRODUCTION

1-5

INTRODUCTION

Barbara Channel is a basin that is about 500 m (1,650 ft.) 

deep. The predominant large-scale patterns of sea surface 

temperature distributions off California and smaller scale, 

but persistent, features such as eddies, fronts (strong temperature gradients), and plumes of cold, upwelled water 

that extend offshore from coastal headlands are depicted 

in Figure 1.3. The coastal current patterns are embedded 

in the complex California Current System (CCS) that 

extends from the Strait of Juan de Fuca at the CanadaUS border to the tip of Baja California, Mexico (Hickey 

1998). A generalized scheme of the CCS is presented in 

Figure 1.3. Waters off northern and central California are 

typically cool because of the southerly flowing California 

Current offshore the continental shelf and upwelling 

events generated over the shelf. Upwelling, which is most 

intense during the spring and summer, is generated by 

winds that blow toward the south along the coast. Cool 

coastal waters enter the Santa Barbara Channel through 

its west entrance at Point Conception. Warm waters from 

the Southern California Bight flow in the opposite direction into the channel through its eastern entrance. The 

geographic orientation of the Southern California Bight 

shelters it from the winds that generate upwelling. Surface 

waters are substantially warmer in the Bight than north 

of Point Conception due to less wind-induced vertical 

mixing, the solar heating of surface waters, and currents 

of subtropical waters entering from the south (Lynn and 

Simpson 1987). The convergence of different water masses 

in the Santa Barbara Channel results in relatively large 

scale differences in physical parameters (e.g., temperature, 

salinity, oxygen, and nutrient concentrations) and biotic 

assemblages (e. g., flora and fauna).

Circulation in the Santa Barbara Channel 

is complex and highly variable (Hendershott 

and Winant 1996; Harms and Winant 1998; 

Winant et al. 1999). Santa Barbara Channel 

circulation typically is characterized by westward flow along the northern boundary of the 

Channel and eastward flow along its southern 

boundary (Figure 1.4).The relative strength of 

these opposing flows varies on scales of days 

to weeks and seasonally. Two opposing forces 

drive channel circulation: a wind gradient that 

is strongest in the west and a pressure gradient 

that is caused by higher water temperatures 

in the east. When these forces are balanced, 

a singular cyclonic (counter-clockwise rotating) eddy forms in the western channel over its 

central basin. Cyclonic circulation is observed 

to be the strongest in the summer and weakest 

in the winter. Unidirectional currents toward 

the east or west throughout the Santa Barbara Channel 

occur predominantly in the winter and tend to be short 

in duration. Throughout the year, smaller cyclonic and 

anticyclonic eddies, fronts, and jets are common in the 

Santa Barbara Channel and may be ephemeral or persistent for days to weeks. Circulation within this channel at 

any particular time is affected by a tendency for cyclonic 

flow and by the variability in the alongshelf currents that 

are of a scale larger than the channel. 

The complex flow patterns and ocean conditions 

within the Santa Barbara Channel are affected by largerscale oceanographic and atmospheric processes associated with intra-annual (e.g., storms and seasonal patterns) and inter-annual (e.g., El Niño and La Niña events) 

variability and interdecadal climate regime shifts. These 

events are teleconnected to tropical Pacific and Pacific basinwide atmospheric phenomena. Oceanographic conditions within the Santa Barbara Channel and along the 

California coast at-large changed dramatically between 

1997 and 1999. Strong, warm-water El Niño conditions 

began late in the summer of 1997 and continued into 

the summer of 1998. Cool-water La Niña conditions 

manifested in early 1999 (Lynn et al. 1998; Hayward et 

al. 1999). El Niño events are linked to delayed and reduced phytoplankton productivity, reduced zooplankton 

biomass, reduced growth and reproduction of coastal 

fishes, and increased mortality during their planktonic 

larval phase (Lenarz et al. 1995; McGowan et al. 1998; 

Kahru and Mitchell 2000). Our findings indicate that fish 

populations responded rapidly to the shift from El Niño 

to La Niña conditions along the coast.

Our observations indicate that, depending on bottom depth, a number of invertebrate 

species are abundant on the shell mounds. Common mound species include three species 

of seastars (Pisaster brevispinus, P. giganteus, and P. ochraceus), 

sunstars (Pycnopodia helianthoides, Rathbunaster sp.), bat stars 

(Asterina miniata), brittle stars, rock crabs (Cancer anthonyi, C. 

antennarius, and C. productus), king crabs (Paralithodes rathbuni), opisthobranchs(Pleurobranchaea californica), spot prawns 

(Pandalus platyceros), octopi (Octopus spp.), and sea anemones 

(Metridium sp.) (M. Love, unpublished observations).

DAN DUGAN

Rock crab

Mussels and sea anemones

DAN DUGAN

Mussels and sea stars

DAN DUGAN

Club anemone and 

kelp rockfish

DAN DUGAN

Metridium sp. and galatheid crab

LOVELAB

Metridium sp.

MILTON LOVE

Spot prawn

Rathbunaster sp.

DONNA SCHROEDER

LOVELAB

a) Upwelling

Point Arguello

Point Conception

b) Relaxation

Point Arguello

Point Conception

c) Cyclonic

Point Arguello

Point Conception

d) Floods

Point Arguello

Point Conception

Figure 1.4. Generalized circulation patterns in the Santa Barbara Channel. 

(a) Upwelling; (b) Relaxation; (c) Cyclonic; (d) Flood east (shown) or west. 

Westward propagating train of cyclonic and anticyclonic eddies have also 

been observed (not shown). Adapted from Harms and Winant (1998).

The invertebrate communities of the jacket, conductors and shell mounds

The jackets and conductors of all platforms are very heavily encrusted with invertebrates. Depth zonation of the invertebrate community is evident. An extremely 

thick layer of mussels extends from the intertidal zone to depths of at least 30 m 

(100 ft) (and to at least 44 m, 145 ft., on some platforms). Both Mytilus galloprovincialis and M. californianus occur in these upper depths, although M. galloprovincialis is more common in the shallower portions of this zone (J. Dugan, personal 

communication). Although mussels dominate this habitat, other invertebrate taxa 

are abundant in this upper layer. Common inhabitants include barnacles, seastars 

(primarily Pisaster giganteus), rock scallops (Crassadoma gigantea), rock oysters and 

jingle shells (Chama arcana and Pododesmus cepio), sea anemones (Anthopleura 

xanthogrammica, Metridium sp.), caprellid amphipods, rock crabs (Cancer 

antennarius), limpets (including Lottia gigantea, Lottia sp., Tectura spp., 

and Acmaea mitra), gooseneck barnacles (Pollicipes polymerus), and sessile 

tunicates. With greater depth, the diverse mussel community wanes and 

tends to be replaced by a blanket of club anemones (Corynactis californicus). At greater depths yet, white anemones (Metridium sp.) and sponges begin to 

dominate these platform structures. These 

organisms, along with crabs (Munida sp.) 

and sea stars, characterize the deepest 

parts of the deepwater platforms we surveyed (J. Dugan, personal communication; 

M. Love, unpublished observations).
1-6

INTRODUCTION

1-7

INTRODUCTION

0–119 ft. depth) and natural outcrops (6–20 m, 20–66 

ft.) (Figure 1.6). Typically, we performed three surveys 

from July to November of each year during 1995 to 2000, 

although some platforms were sampled less frequently. 

Fish enumeration methods consisted of fish counts and 

fish size estimates using both visual and underwater 

videography methods. Visual surveys recorded fish 

density and size (total lengths) using underwater plastic 

sheets and slates. All divers performing visual counts 

had received training in size estimation. Additional size 

estimates were obtained using a Hi-8 mm video camera 

and laser calibration system. The visual estimates of size 

and relative abundance were used first in data analyses 

and video size data were occasionally used to supplement 

visual estimates.

In each platform survey, scuba divers recorded observations while swimming a pattern which incorporated all 

four corner legs and the major horizontal crossbeams and 

portions underneath the platform jacket at three different 

depths (Level 1 range 6–10 m, 20–33 ft.; Level 2 range 12–

21m, 40–70 ft.; Level 3 range 25–36 m, 83–119 ft.) (Figure 

1.7). Natural reef surveys consisted of diver observations 

Superimposed on the inter-annual variability, which 

include the El Niño and La Niña anomalies, are climateocean changes that occur throughout the entire North 

Pacific Basin on decadal scales. A well documented climatic shift occurred rapidly during 1976 to 1977. It was 

marked by abrupt changes in sea surface temperature 

patterns and the circulation of a predominant atmospheric feature of the northeast Pacific known as the 

Aleutian Low. Since that time in the northeast Pacific, 

macrozooplankton biomass and a number of nearshore 

fish stocks in the California Current system have declined 

(Roemmich and McGowan 1995). In 1999, a number of 

physical and biological changes in the northeast Pacific 

indicated another shift from a warm to cool regime 

(Bograd et al. 2000). Recruitment of young-of-the-year 

rockfishes to platforms in the Santa Barbara Channel 

was exceptionally high in 1999. The permanence of this 

shift to cool conditions is uncertain.

Small-Scale Oceanographic Variability within the 

Santa Barbara Channel 

Interesting patterns of fish abundance are related to 

the complexity and dynamics of the hydrography and 

circulation within the Santa Barbara Channel. Certain 

aspects of our research are focussed on the biological 

significance of fronts and eddies to the transport and survival of early juvenile stages of marine fishes. Typically, 

these features are generated by local-scale interactions 

of wind, opposing water mass currents, and tides. This 

is especially true where the coastline is characterized by 

irregular topography and bathymetry, as is the case in 

the Santa Barbara Channel and the Southern California 

Bight (Owens 1980) (Figure 1.1). As mentioned, fronts 

and eddies affect how fishes are pelagically distributed in 

the region and may ultimately affect the timing and location of young-of-the-year settlement. For example, we 

sampled high densities of pelagic juvenile fishes within 

an eddy in the Santa Barbara Channel. The location of 

the eddy was determined by analysis of surface current 

maps generated from remote-sensing radar (Nishimoto 

and Washburn 2002). Furthermore, we have discovered 

that sea surface temperature fronts can be used to identify 

boundaries that separate reef habitat with high and low 

levels of juvenile rockfish settlement (Love, Nishimoto, 

Schroeder, and Caselle 1999). Mesoscale features that are 

visible in sea surface temperature images and surface 

current maps potentially can be used along with other 

oceanographic data to identify areas where benthic recruitment is likely.

The Santa Barbara Channel as a biological 

transition zone

Marine organisms from distinctively different 

northern and southern biogeographic communities 

occur in the Santa Barbara Channel as resident populations or as seasonal or occasional visitors making this a 

rich, biological transition zone (Horn and Allen 1978). 

A few examples of warm-temperate and subtropical 

fishes that are more common in southern California 

(defined as south of Point Conception) than in central 

California and that we have observed at platforms in 

the Santa Barbara Channel are Mexican rockfish, kelp 

bass, yellowtail, and Pacific barracuda. Examples of 

cool-temperate fishes that have distributions centered 

from central California to the Pacific Northwest and 

may occur at platforms include cabezon, kelp greenling, lingcod, and many rockfishes (e.g., blue, canary, 

widow, and yelloweye). 

Methods

A major research objective of this project was to describe and compare the spatial and temporal patterns of fish 

assemblages around platforms and natural rock outcrops. 

Between 1995 and 2001, we surveyed platforms sited over a 

wide range of bottom depths, ranging between 29 and 224 

m (95 and 739 ft.) and sited from north of Point Arguello to 

off Long Beach. We also surveyed shallow-water and deepwater rock outcrops, many in the vicinity of platforms. 

Scuba surveys were conducted at shallow depths (< 36 m, 

119 ft.), and submersible surveys at deeper depths.

Most of our platform surveys were conducted at nine 

structures (Platforms Irene, Hidalgo, Harvest, Hermosa, 

Holly, Gilda, Grace, Gina, and Gail)located in the Santa 

Barbara Channel and Santa Maria Basin (Figure 1.1). Between 1995 and 2000,we conducted scuba surveys on the 

shallow portions of these nine platforms (Figure 1.1b). 

The shallowest of the nine platforms, Gina, was surveyed 

from top to bottom using scuba. Deeper-water surveys 

between 1995 and 2001, using a research submersible, 

surveyed the same platforms excluding the bottom of 

Gilda and all of Gina (Figure 1.1a). In 1998, we made one 

submersible survey around Platform Edith, located off 

Long Beach (Figure 1.1c) and in 2000 we made partial 

submersible surveys around platforms C, B, A, Hillhouse, 

Henry, Houchin, Hogan, and Habitat (Figure 1.1a). Poor 

water visibility prevented us from completing the surveys 

around the latter eight structures. Appendix 1 lists all 

of the platforms and includes their dimensions, depths, 

locations, and the years these structures were surveyed. 

Nine nearshore, shallow-water rock outcrops, seven 

on the mainland and two at Anacapa Island were surveyed from 1995 to 2000 by scuba (Figure 1.1b). These 

surveyed natural outcrops are distributed across the 

Santa Barbara Channel region and are exposed to water 

masses similar to that of the surveyed oil platforms. In 

addition, we surveyed over 80 deeper-water outcrops, in 

waters between 30 and 360 m (100 and 1,180 ft.) deep 

(Figure 1.5). Most of these deeper-water sites were visited 

once, a few were surveyed during as many as four years 

and one outcrop, North Reef near Platform Hidalgo, was 

sampled annually.

Shallow Portions of Platforms and Nearshore Natural 

Outcrops

Scuba surveys estimated density (individuals per 

hectare), mean size (total length), and species composition of reef fishes in shallow portions of platforms (0–36 m, 

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Submersible Dive Sites

1995-2001

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Figure 1.5. Platform and natural outcrops surveyed by Delta submersible, 1995–2001. Concentric rings denote sites surveyed 

in more than one year. Stars indicate platforms. See Figure 1.1 for names of platforms.
1-8

INTRODUCTION

1-9

INTRODUCTION

collected along four haphazardly placed 30 m length x 

2 m width x 2 m (100 x 7 x 7 ft.) height belt transects, 

two transects each at approximately 7 m (23 ft.) and 14 

m (46 ft.) bottom depths corresponding to the inshore 

and offshore portions of the reef. Each transect included 

sampling of three strata: surface, midwater, and bottom 

portions of the water column, one above the other. 

Habitat measures using a random point count method 

(2 points/m) were taken along the same transects for 

characterization of physical and biological attributes. 

Quantified habitat features included relief height (0 to 

0.1 m, 0.1 to 1 m, 1 to 2 m, and > 2 m), substrate type 

(sand/mud, cobble, and rock), and percent cover of ses-

sile invertebrates and fleshy algae. We also measured the 

percent cover of surface canopy of giant kelp, Macrocystis 

pyrifera, and stipe density of large kelps, especially M. 

pyrifera, Pterygophora californica, and Eisenia arborea, 

along the transects.

Deeper Portions of Platforms and Deeper Natural 

Outcrops

Below scuba depths, we surveyed fish assemblages 

using the Delta submersible, a 4.6 m, 2-person vessel, 

operated by Delta Oceanographics of Oxnard, Califor-

nia (Figure 1.8). Aboard the Delta, we conducted belt 

transects about two meters from the substrata, while the 

submarine maintained a speed of about 0.5 knots. At the 

platforms, transects were made around the bottom of the 

platform and around each set of cross beams to a mini-

mum depth of 20–30 m (66–100 ft.) below the surface (e. 

g., midwater habitat). The belt transect was also used to 

sample the shell mounds and natural rock outcrops. The 

shell mounds and outcrops were sample 

in consistently the same fashion as the 

platform method described above.

Submersible surveys were conducted 

during daylight hours between one hour 

after sunrise and two hours before sunset. 

During each transect, observations were 

taken from one viewing port on the star-

board side of the submersible. An external-

ly mounted Hi-8 mm video camera with 

associated lights filmed the same viewing 

fields as seen by the observer. The observer 

identified, counted, and estimated the 

lengths of all fishes and verbally recorded 

those data on the video. All fishes within 

2 m (7 ft.) of the submarine were counted. 

Densities were calculated as fish per 100 m2

. Fish lengths were estimated using a pair 

of parallel lasers mounted on either side of the external 

video camera. The projected reference points were 20 cm 

(8 in.) apart and were visible both to the observer and 

the video camera. An environmental monitoring system 

aboard the submarine continuously recorded date, time, 

depth, and altitude of the vessel above the seafloor. The 

environmental data was overlaid on the original videotape 

upon completion of each survey.

Transect videos were reviewed aboard the research ves-

sel or in the laboratory. Field observations were transcribed 

into a database. For each fish, we recorded the following 

Figure 1.6. A scuba diver surveys fishes around Platform Gina.

Figure 1.7. A schematic illustration of the diver platform 

surveys.

Figure 1.8. The research 

submersible Delta. Delta is a 

2-person untethered vehicle.

Figure 1.9. Annual midwater 

trawling and oceanographic 

surveys, 1995–2000. 

(a) F/V Gus-D was chartered for 

research; (b) pelagic juvenile 

rockfish and other small fishes 

were sorted from the catch that 

included euphausiids and various 

jellies; (c) modified Cobb trawl 

rolled around spool; (d) deploy-

ment of conductivity-tempera-

ture-depth profiler. 

JAMES FORTE
1-10

INTRODUCTION

1-11

INTRODUCTION

information: (1) species (if known); (2) estimated total 

length; (3) the habitat it occupied (e.g., rock, sand, mud, 

cobble, boulder); (4) its position relative to the substrate 

(e. g., in crevice, on reef crest, on slope, above structure); 

and (5) the distance of the fish from that substrate.

Midwater Trawling and Oceanographic Surveys

Recruitment, the settlement to a benthic habitat of 

pelagic juveniles or larvae, is an important process in-

fluencing the fish assemblages found on platforms and 

natural outcrops. To better understand spatial and tem-

poral patterns of recruitment and sources of recruitment 

variability, we conducted annual midwater trawling and 

oceanographic surveys in the vicinity of the Santa Barbara 

Channel and Santa Maria Basin. Our goal was to describe 

how regional patterns of circulation and distribution of 

hydrographic features (such as fronts and eddies) influ-

enced the distribution and relative abundance of pelagic 

juvenile fishes. Our focus on this life stage would allow 

emphasis on settlement and delineation of nursery habi-

tats, including both platforms and natural outcrops.

Annual midwater trawling and oceanographic sur-

veys were conducted from 1995 through 2000. Sampling 

was conducted during June to coincide with the time 

when the most juveniles of the early spring spawning 

rockfishes would be present in the water column. A modi-

Figure 1.10. Annual midwater trawling surveys, 1995–2000. Map of stations where trawl samples were collected. Surveys typically were conducted in June and included 10 nights of sampling.

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Midwater Trawling Surveys

June-July, 1995–2000

fied anchovy trawl with a codend of 9 mm mesh was used 

to collect samples at depths between 20 m and 55 m 

(66–182 ft.) below the surface (Figure 1.9).Towing speed 

was about 2 knots, and trawling time was 15 minutes at 

the targeted depth. All fishing was conducted at night to 

minimize net avoidance. Fishes were identified to species 

if possible and measured in the laboratory. The shipboard 

surveys included vertical profiling of water properties at 

all trawling stations so that we could associate patterns 

of fish abundance with local hydrographic conditions. 

Salinity, potential temperature, and potential density 

anomaly, and dynamic height were derived from the 

data collected using a conductivity-temperature-depth 

(CTD) profiler (SBE-19, SeaBird Electronics). The CTD 

was lowered to 200 m (660 ft.) or to about 10 m (33 ft.) 

above the bottom at shallower stations. Daily satellite 

imagery, hourly sea surface current maps, and underway 

sea surface temperature observations were used to direct 

sampling when it was based on the location of surface 

circulation features such as fronts and eddies. The specific 

objective of each survey differed from year to year, see 

Love et al. (1997, 1999, 2001), Nishimoto (2000), and 

Nishimoto and Washburn (2002) for details. Surveys 

were conducted throughout the Santa Barbara Channel, 

in adjacent waters outside of the channel, and around 

the Northern Channel Islands (Figure 1.10).

Black-and-Yellow rockfish at Platform Holly.

DAN DUGAN
1-12 2-1

Oil and gas seeps, often the result of geological defor-

mation of the oil-saturated strata, are a common global 

occurrence. The famous La Brea tarpits, found near 

downtown Los Angeles, is just one of many seeps found 

in California. Offshore, seeps are visible on the ocean 

surface as oil slicks or gas bubbles. As noted by California 

Resources Agency (1971), “Some [seeps] remain dormant 

for extended periods of time and then become reacti-

vated, probably by pressure buildup or earth movement. 

Because of the transient nature of many seeps, an accu-

rate count is difficult to obtain; however, it appears that 

there are probably 50 to 60 seeps and seep areas on the 

ocean floor between Point Conception in Santa Barbara 

County and Huntington Beach in Orange County.”

Native Americans in many parts of California, but 

particularly along the southern California coast, mined 

those land seeps that contained hard, high-grade as-

phaltum. The soft tar derived from offshore seeps and 

diverted to beaches was rarely, if ever, used. California 

Native Americans used asphaltum in a variety of ways. 

Baskets and water bottles were made watertight, arrow-

points and hook barbs attached to shafts, broken stone 

vessels repaired, canoes caulked and sealed and shell 

decorations were inlaid on various objects. The Chu-

mash of coastal southern California melted asphaltum 

and mixed it with pine resin to create an effective adhesive 

for many of these uses.

Early European explorers noted the presence of these 

seeps. “The Spanish explorer Fages, in 1775, said that ‘At 

a distance of two leagues from this mission [San Luis 

Obispo] there are as many as eight springs of a bitumen 

or thick black resin...’ Fr. Pedro Font, in 1776, while 

near Goleta in Santa Barbara County wrote ‘...much tar 

which the sea throws up is found on the shores, sticking 

to the stones and dry. Little balls of fresh tar are also 

found. Perhaps there are springs of it which flow out into 

the sea, because yesterday on the way the odor of it was 

perceptible, and today...the scent was as strong as that 

perceived in a ship or in a store of tarred ship tackle and 

rope” (Heizer 1943).

While European settlers in California also utilized 

asphalt from terrestrial seeps in limited ways, primarily 

for water proofing and lubrication, there was relatively 

little interest in oil seeps until about 1850, when it became 

more widely known that kerosene, an excellent substitute 

for whale oil in lamps, could be distilled from crude oil. 

While Dr. Abraham Gesner, a Canadian geologist, is 

officially credited with inventing this process in 1849, 

others may also have stumbled onto this idea. In Cali-

fornia, the first person known to use partially refined oil 

for illumination was General Andreas Pico, the brother 

of Pio Pico, the last Mexican governor of California. In 

1850, General Pico distilled kerosene from oil taken from 

hand dug pits in Pico Canyon (near Newhall, southern 

California) and used it for lighting a home. By 1854, 

miners had excavated into Sulphur Mountain in Ventura 

County (southern California), were hauling out the oil 

that seeped into their tunnels and had set up stills to 

produce kerosene. Throughout the 1850 and 1860s, vari-

ous companies mined seeps for petroleum and produced 

kerosene or kerosene-like products.

In California, the first well (as opposed to hand-dug 

pit) that was designed to produce oil was a failure. It was 

drilled in Humboldt County in 1861 and it, along with 

others in the same county between 1861 and 1864, came 

up dry. However, the first productive well, drilled in 1865, 

came in from this county. This was quickly followed up 

by successful wells in Ventura and other localities. It was 

not until 1876 that the first truly commercial well was 

developed in Pico Canyon, the site of General Pico’s first 

pit mine. The next 20 years saw production rapidly esca-

late, with new fields explored and developed in a number 

of locations in central and southern California.

The first oil production from submarine strata in 

California occurred in Summerland, a sleepy village 

south of Santa Barbara formally founded in 1889 as a 

spiritualist colony. For years, Summerland residents had 

noted both the heavy scent of oil that frequently hung 

over the community and the numerous seeps that dotted 

their coastline. In fact, natural gas was so plentiful that 

when boys wanted to play baseball at night “...they would 

drive short pieces of pipe into the ground about four or 

five inches, and would light them, and there would be 

a gas flame at least a foot high from the top of the pipe. 

Fifteen or twenty of these pipes along the edge of the road 

gave plenty of light for them to play after dark. When they 

got called in to go to bed, each had a flat board, and they 

would whack the board down over the flame, and out it 

would go.” (Lambert 1975). 

In the late 1880s and early 1890s, several Summer-

Chapter 2

A BRIEF HISTORY OF OIL DEVELOPMENT 

IN SOUTHERN CALIFORNIA

Milton S. Love

Opposite: Flag rockfish at Platform Harvest. (Photograph by Donna Schroeder)
2-2

A BRIEF HISTORY OF OIL DEVELOPMENT IN SOUTHERN CALIFORNIA

2-3

A BRIEF HISTORY OF OIL DEVELOPMENT IN SOUTHERN CALIFORNIA

land residents had struck oil while digging water wells 

and at least one would fill barrels from a bucket, haul 

them by buckboard to Santa Barbara, and sell the oil 

to laundries. Drilling for oil just back from the ocean 

commenced shortly after and by 1897 both the beaches 

and short stretch between ocean and coastal hills were 

blanketed with drilling rigs. In 1896, W. L. Watts of the 

California State Mining Bureau reported that “It is also 

evident that the oil yielding formations extend south 

into the ocean...At low tide, springs of oil and gas are 

uncovered on the seashore.” (Rintoul 1990). 

True to the prediction, the first pier holding a well 

was built in 1897. This was perhaps the world’s first well 

brought in over water, a record also reportedly claimed 

for the Baki (formerly Baku) (Republic of Azerbaijan) 

oil fields in the Caspian Sea and by Pennsylvania for 

drilling into Lake Erie. Within a few years there were 11 

piers (harboring over 200 wells), one of them stretching 

1,230 feet offshore (Figure 2.1). The Summerland piers 

continued to produce oil until 1939, when the last well 

was destroyed by high tides and high surf. 

In the 1920s, a series of discoveries along the Santa 

Barbara Channel, particularly at Rincon (northwest 

of Ventura) and Ellwood and Capitan (west of Santa 

Barbara) led to additional offshore drilling. While all 

of these discoveries were made on land, development 

quickly extended onto piers. However, rather than being 

built of wood, these piers were more heavily constructed 

of steel pilings and reinforced concrete caissons.

The year 1932 saw the erection of the first oil platform off California and perhaps in the world. In that 

Depression year, the Indian Petroleum Company was 

faced with a dilemma. Geological evidence implied that 

productive oil-bearing strata lay offshore of Rincon (just 

northwest of Ventura). However, the costs of building a 

pier out to that formation were prohibitive. The company 

solved the problem by building part of a pier, located 

about 1,200 feet beyond the end of the nearest pier. Constructed of steel in 38 feet of water, the aptly named “Steel 

Island” was eventually home to three wells (Figure 2.2). 

It lasted until 1 January 1940, when “...mountainous 

waves battered the platform. The structure went down. 

There was no loss of life, but equipment was destroyed 

and wells damaged. Rohl-Connolly Company, marine 

contractors, removed equipment, derrick and steel pilings from the ocean floor; cut off casing at the floor of 

the ocean; and placed 6-foot cement plugs in the tops of 

the water strings” (Rintoul 1990).

Later oil and gas discoveries that were of importance 

to offshore development included those at Huntington 

Beach, Wilmington and Seal Beach. However, it was not 

until 1954, that the next step in offshore production occurred with the creation of the first man-made drilling 

island, “Monterey”, situated 1.5 miles offshore of Seal 

Beach in 42 feet of water. Construction on the island 

commenced in 1952, but a lawsuit by the city of Seal 

Beach prevented drilling until 1954. The circular island 

“...75 feet in diameter, had an outer rim formed of interlocking sheet-steel piling driven into the ocean floor 

to depths of 15 to 20 feet. The interior was filled with 

rock and sand barged in from Catalina Island” (Rintoul 

1990). In succeeding years five other oil islands (Grissom, 

White, Freeman, Chaffee, and Esther) were built. 

Oil islands were only practical in relatively shallow 

waters and when industry-led seismic surveys and bottom coring discovered potential fields in deeper offshore 

waters, the stage was set for the development of oil platforms. In June 1958, the California State Lands Commission held its first sale of tidelands leases, ending a freeze 

that had held up offshore drilling on new sites. The first 

Figure 2.1. Oil piers off Summerland, California, about 1904 (from Rintoul 1990).

Figure 2.2. Built off Rincon, southern California, in 1932, the “Steel Island” was one of the first oil platforms in the world. 

PHOTO COLLECTION/LOS ANGELES PUBLIC LIBRARY

platform constructed was Platform Hazel, located about 

two miles offshore of Summerland in 100 feet of water. As 

noted in Rintoul (1990) regarding Hazel’s construction, 

“In that same month, Standard [Oil] towed an imposing 

tower a distance of 210 miles... to the Summerland tract. 

The tower was 75 feet square and 170 feet high. It was a 

major component of Platform Hazel and was to serve as 

the foundation on which the 110-foot square deck would 

be mounted...The tower was floated to the job site on 

the four big caissons that formed the bottom portion of 

the tower’s legs, each 40 feet high and 27 feet in diameter. 

Each caisson was pressurized to prevent leakage and also 

ballasted with 90 tons of sand for stability...Once on bottom, the caissons were sunk 22 feet into the ocean floor 

by means of high pressure water and air jets that literally 

hosed away the bottom sands, allowing the caissons to 

rest on hard ground. The final anchoring was accomplished by filling the caissons with 6,000 tons of sand 
2-4

A BRIEF HISTORY OF OIL DEVELOPMENT IN SOUTHERN CALIFORNIA

3-1

Stripetail rockfish on shell mound of Platform Gail.

LINDA SNOOK

and concrete...The cost of building and installing the 

platform was $4 million.” In September 1958, Standard 

Oil began drilling from the newly constructed platform 

and within one month the first well, bottoming out at 

7,531 feet began producing 865 barrels per day. This was 

followed two years later by the construction of nearby 

Platform Hilda.

In subsequent years, a number of platforms were installed in both state and (beginning in 1967 with Platform 

Hogan) federal waters in southern California. However, 

expansion of offshore oil drilling came to an abrupt halt 

in 1969, with the disastrous blowout and subsequent oil 

spill at Platform A (installed in 1968) in the Santa Barbara 

Channel. And while discussion of both opposition and 

support for oil development are beyond the scope of this 

report (see Beamish et al. 1998, Nevarez et al. 1998, and 

Paulsen et al. 1998 for more information), it is safe to 

say that the subsequent environmental concerns about 

the safety of offshore oil exploration, development, and 

production delayed further drilling for a number of years. 

It was not until the late 1970s that installation of new 

platforms resumed. No new platforms have been erected 

since 1989 (Nevarez et al. 1998).

How do platforms get their names? 

On the Pacific Coast, platform names have to conform to a set of rules promulgated by the U. S. Coast 

Guard. The Coast Guard created a series of zones 

(“15-minute quadrangles”) along the Pacific Coast 

beginning at the U. S. – Mexican border. The names 

of all platforms in a zone must begin with the same 

letter. Platforms in the first zone, off San Diego, would 

begin with “A”. The southern-most platforms (Emmy, 

Edith etc.) lie off Long Beach, in the “E” zone. 

Industry personnel imply that the choice of names 

have often been made in a disarmingly casual way. 

For instance, the project engineer for Hermosa apparently named that structure after the elementary 

school attended by his daughter. Ellen and Elly are 

said to honor the wives of the engineers in charge of 

those platforms’ construction. Hondo, meaning “big” 

in Spanish, was so christened because at the time it 

was the tallest (measured from the seafloor) of the 

California platforms. One story has it that, because a 

nearby platform was later installed to tap the same 

reservoir as Hondo, it was named Harmony. Hogan 

and Houchin were the surnames of two presidents of 

Phillips Petroleum.

Why do Platforms A, B and C, despite their locations in the H zone, not have “H” names? These were 

installed in the days before the Coast Guard regulations were mandatory.

There was no single characteristic fish assemblage that 

could be described for the oil platforms and natural 

outcrops of central and southern California. However, 

we identified a number of patterns in fish diversity and 

abundance that corresponded to bottom depth, geographic area, and year. Depth played an important role 

because, in general, rockfishes numerically dominated fish 

assemblages around platforms and deep natural reefs, and 

rockfish species segregate themselves according to habitat 

depth. We also observed biogeographic partitioning in 

species composition, where northerly platforms show 

the influence of the Oregonian province and southerly 

platforms show the influence of the San Diegan province. 

These zoogeographic patterns were more conspicuous 

in shallow water fish assemblages. The large inter-annual fluctuations in juvenile fish recruitment observed 

during the studies may have been generated by the large 

inter-annual variability in oceanographic conditions (e.g., 

upwelling, El Niño-Southern Oscillation events). Since 

juveniles of many species inhabited shallow and midwater 

portions of oil platforms, the greatest temporal variability 

in fish abundance occurred at these depths. 

We present more detailed summaries of fish assemblages identified by the two different survey methods 

(scuba and submersible) in the sections below. The 

common and scientific names of fishes observed in 

these studies are listed in Table 1. 

1. Shallow Water Fish Assemblages: 0–36 m (119 ft.)

Findings at a Glance

A combination of regional and local processes 

influenced patterns of reef fish assemblages in shallow water. At regional scales, composition and relative abundance of reef fishes often shifted abruptly as 

oceanography changed. This shift delineated a cooltemperate assemblage in the western Santa Barbara 

Channel, and a warm-temperate assemblage in the 

eastern Santa Barbara Channel. This distinct spatial 

pattern was reflected in both platform and natural reef 

habitats. There was greater variability in platform species assemblages and population dynamics compared 

to natural outcrop assemblages and dynamics, and 

this was most likely caused by the offshore position 

and greater sensitivity of platform habitats to changing oceanographic conditions. Local processes which 

affected fish distribution and abundance were related 

to habitat features, where depth, relief height, and presence of giant kelp all played important roles. We found 

that the majority of juvenile rockfish recruits resided at 

depths greater than 26 m (86 ft.), although there were 

differences among species.

Except where noted, the following synopsis encompasses platforms Irene, Hidalgo, Harvest, Hermosa, 

Holly, Grace, Gilda, Gail, and Gina and are based on 

diver surveys conducted between 1995 and 2000.

1a. General Patterns

The two primary research objectives were to (1) 

describe the spatial and temporal variability of shallow 

water (less than 36 m, 119 ft.) fish assemblages residing 

on oil/gas production platforms and natural outcrops, 

and (2) describe the relative importance of regional processes (e.g., oceanographic patterns) compared to local 

processes (e.g., habitat features) in generating observed 

patterns of reef fish assemblages. An understanding of 

mechanisms which structure marine populations is necessary to predict the outcome of resource management 

decisions related to marine fisheries, platform decommissioning, and marine protected areas on fish assemblages 

within the Santa Barbara Channel region (including the 

Santa Maria Basin). A list of species observed at each 

platform is given in Appendix 2.

We find that a combination of regional and local 

processes influenced patterns of reef fish assemblages in 

shallow water. At regional scales, composition and relative abundance of reef fishes often shifted abruptly as 

oceanography changed. This shift delineated a cool-temperate assemblage in the western Santa Barbara Channel, 

and a warm-temperate assemblage in the eastern Santa 

Barbara Channel. Rockfishes and surfperches dominated the cool-temperate assemblage, and damselfishes, 

wrasses, and sea chubs dominated the warm-temperate 

assemblage. This distinct spatial pattern was reflected in 

both platform and natural outcrop habitats. 

Within each of the cool- and warm-temperate assemblages, local habitat features modified patterns of 

CHAPTER 3

A REVIEW OF BIOLOGICAL AND 

OCEANOGRAPHIC SURVEYS: 

RESULTS AND ANALYSES

Milton S. Love, Donna M. Schroeder, and Mary M. Nishimoto
3-2

RESULTS AND ANALYSES

3-3

RESULTS AND ANALYSES

species abundance and distribution. For example, kelp 

surfperch and giant kelpfish were only observed on rocky 

outcrops that possessed stands of giant kelp, Macrocystis pyrifera. Other factors likely to have been important 

were outcrop or platform depth and relief height. These 

local scale features sufficiently decoupled sites within 

an oceanographic region (cool- or warm-temperate) 

to make broad generalizations about fish assemblages 

difficult, especially within platform habitats.

Temporal dynamics of reef fish assemblages also 

resulted from a complex, dynamic interaction between 

regional oceanography and local habitat features. The 

diverse array of oceanographic conditions that occurred 

during the six-year survey period appeared to strongly 

influence regional dynamics of fish assemblages. The 

1997–1998 El Niño event corresponded to a 

large increase in juvenile recruitment of species which dominated the warm-temperate 

fish assemblage (e.g., blacksmith), while the 

1999 La Niña event corresponded to a large 

increase of juvenile recruitment of species 

which dominated the cool-temperate fish 

assemblage (e.g., rockfishes). Severe winter storms that accompany El Niño events 

propagated into small-scale variability at 

some sites. For example, the scouring effect 

of severe storm waves depleted red algal turf 

(a forage base for small crustaceans and fish) 

on two shallow natural outcrops. This forage 

base reduction may have been the primary 

cause of the observed synchronous decline in 

surfperch abundance at the same outcrops.

1b. Shallow Water Fish Assemblages Surrounding 

Oil/Gas Production Platforms

As observed on natural outcrops (see Section 1d), 

shallow water fish assemblages surrounding oil/gas production platforms show distinct spatial patterns which 

correspond to oceanographic patterns in the Santa Barbara Channel. Rockfishes are numerically dominant in 

west channel platform fish communities, although 1999 

was a strong recruitment year for juvenile rockfish at all 

platforms. Blacksmith and halfmoon are numerically 

dominant in east channel platform assemblages. Platform 

fish assemblages appeared to respond faster and more 

dramatically to changing oceanographic conditions than 

natural reef assemblages, perhaps due to their offshore 

position and higher proportion of juvenile fishes. 

There were notable differences among platforms 

within an oceanographic region. These differences 

may be due to water depth in which the platform is 

positioned, where deeper water can inhibit species such 

as surfperches from migrating onto platform habitat. 

Among-platform differences may also be influenced by 

food availability or other factors. During the 1997–1998 

El Niño event, juvenile blacksmith recruited onto all 

platforms, but did not recruit onto Tarantula Reef, the 

closest natural reef to west channel platforms surveyed 

in this study. This observation suggests that platforms 

may “capture” pelagic stages of some reef fish species 

that might have otherwise perished. 

The fish assemblage observed at Platform Gina 

(depth 29 m, 95 ft.) is noteworthy because of its very 

high density of kelp bass and because of the large 

diversity of rockfishes that recruit to its shell mound 

habitat. Anecdotal observations at a nearby shipwreck 

did not record either of these characteristics in its local 

fish assemblage. High turnover of fish species diversity 

has also been noted at Platform Gina (Love, Nishimoto, 

Schroeder, and Caselle 1999).

1c. Depth Distribution of Juvenile Fish Recruitment 

on Oil Platforms

For all fishes observed at all Southern California 

Bight platforms surveyed at shallow depths, approximately 27% were observed in the shallowest portions of 

platform habitat (6–12 m, 20–40 ft.). Most of these were 

pelagic fishes, such as anchovy and barracuda. Twentyseven percent of all fishes were observed at intermediate 

depths (15–26 m, 50–86 ft.), and 46% were observed at 

deeper depths (27–36 m, 89–119 ft.). We observed that 

the majority of juvenile rockfish recruits resided at depths 

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Figure 3.1. Percent of juvenile fish density observed during scuba surveys at different depths on offshore platforms during 

1995–2000. Depth ranges for each strata: level 1 (6–12 m), level 2 (15–26 m), level 3 (27–36 m). 

greater than 26 m (96 ft.) (Figure 3.1), although there were 

differences among species. The olive-yellowtail group and 

copper-complex species group (black-and-yellow, copper, 

gopher, and kelp rockfishes) had the largest percentages 

residing at shallower depths. Our observations on copper-complex rockfishes represent a somewhat different 

vertical distribution than that described by Holbrook et 

al. (2000). This disparity may be due to differences in 

surveyed platforms and program duration (6 platforms 

within one biogeographic area during 1995–7 versus 9 

platforms in 3 biogeographic areas during 1995–2000). 

This difference underscores the importance of evaluating platforms on a case-by-case basis and in developing 

monitoring programs over multiple years.

Our results correspond with Holbrook et al. (2000) 

regarding vertical distribution of midwater juvenile 

rockfishes (e.g., bocaccio, blue, and widow) where the 

vast majority of individuals recruited to depths greater 

than 26 m (86 ft.). The majority of individuals of other 

rockfish species such as squarespot, treefish, and the 

Sebastomus subgenus (e.g., rosy, greenspotted, starry 

rockfishes, and others) are also found below 26 m (86 

ft.). Kelp and painted greenling recruits, two species 

associated with the cool-temperate fish fauna, mimic 

the vertical distribution of rockfish recruits, preferring 

deeper portions. In contrast, garibaldi and blacksmith 

recruits, two species associated with the warm-temperate 

fish fauna, favor upper portions of platforms, suggesting temperature may play a role in determining depth 

distribution of juvenile fishes at platforms.

1d. Fish Assemblages on Nearshore Natural Outcrops

The relative importance of spatial versus temporal 

variability in structuring fish assemblages on shallow 

natural outcrops differed among sites. Ordination analysis revealed that natural outcrops in the west channel 

tended to be more sensitive to temporal variability than 

those outcrops positioned in the east channel. This seems 

intuitive since west channel outcrops are closer to areas 

of intense and temporally variable upwelling processes 

which affect mean water temperature, primary production, and dispersal processes of larvae. 

Kelp bass at a nearshore platform.

JAMES FORTE
3-4

RESULTS AND ANALYSES

3-5

RESULTS AND ANALYSES

Similar to platform habitats, the fish assemblages on 

natural outcrops showed distinct spatial patterns that 

seemed to correspond to regional oceanographic patterns 

in the Santa Barbara Channel. Rockfishes and surfperches 

were important species in west channel fish communities, although 1999 was a strong recruitment year for 

juvenile rockfishes at most natural outcrops. Blacksmith, 

garibaldi, sheephead, opaleye, and rock wrasse were im-

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Figure 3.2. 3.2a. Canonical Discriminant Analysis of the 

bottom and shell mound fish assemblages at seven platforms, 1996–2001. 3.2b. Canonical Discriminant Analysis 

of the bottom and shell mound species found around seven 

platforms, 1996–2001. Two groups, one characteristic of 

shallow platforms, the other of deeper structures are apparent. Black dots represent species that were not strongly 

associated with either axis.

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Platform Holly species

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Figure 3.3. 3.3a. Canonical Discriminant Analysis of midwater fish assemblages at seven platforms, 1996–2001. Note 

that the Platform Holly fish assemblage is distinct from the 

others. 3.3b. Canonical Discriminant Analysis of the midwater species found around seven platforms, 1996–2001. 

Note that a group of species tends to be more characteristic 

of Platform Holly than other platforms. Dots represent species that were not strongly associated with either axis.

Grace, and Gail, based on surveys conducted between 

1995 and 2001 from the research submersible Delta.

2a. General Patterns

All of the platforms studied by submersible had 

three distinct fish assemblages, midwater, bottom, and 

shell mound (Figure 3.2a). Rockfishes, totaling about 

35 species, dominated all three fish assemblages. Fish 

densities at most platforms tended to be highest in the 

midwater reflecting the depth preferences of young-ofthe-year rockfishes that represented the most abundant 

size class of fishes.

Midwater assemblages were more similar to each 

other regardless of platform location and bottom depth. 

The assemblage at Platform Holly had the only distinct 

midwater assemblage (Figure 3.3a). A suite of species 

(e.g., calico, copper, and gopher rockfishes, pile, and 

sharpnose seaperches) characterized this particular assemblage (Figure 3.3b). Holly has the shallowest bottom 

depth (standing in 64 m, 211 ft.), and it might be that 

these shallow demersal species were able to occupy these 

shallow midwater crossbeams. The midwater fish assemblages around the other platforms showed no systematic 

depth or geographic relationships. 

The composition of platform bottom and shell 

mound fish assemblages was dependent on the bottom 

depth of the platform (Figure 3.2a) and certain species 

are characteristic of either shallow or deep benthic 

habitats (Figure 3.2b). Platforms Holly and Irene (64 m 

and 73 m; 211 and 241 ft., respectively) were dominated 

by brown, calico, copper, and vermilion rockfishes and 

lingcod. In deeper waters, Platforms Hermosa, Harvest, 

and Gail (183 m, 205 m, and 224 m; 604, 677, and 739 

ft., respectively) were dominated by greenblotched, 

greenspotted, and greenstriped rockfishes. Platform 

Hidalgo, and to a certain extent Platform Grace, both at 

intermediate depths (130 m and 96 m, 429 and 317 ft., 

respectively), were inhabited by species common to both 

the shallower and deeper platforms. In general, our data 

suggests that shell mound fish assemblages most closely 

resemble the fish assemblages of their adjacent platform 

bottoms (Figure 3.2a). Fishes living on the shell mounds 

are generally smaller, and presumably younger, than the 

same species living around the platform bottom. 

portant species in east channel fish communities. Kelp 

bass, black surfperch, and senorita were abundant at 

all sites. Because we observed abrupt spatial changes 

in abundance for many species in the Santa Barbara 

Channel, it is tempting to attribute these patterns solely 

to oceanographic processes. However, habitat features 

may covary with oceanography, and we are currently 

unable to distinguish between these processes. 

Dispersal of pelagic stages does not appear to be 

the primary factor in structuring fish assemblages. For 

the eight common species in the warm-temperate assemblage that have pelagic larvae, six species exhibited 

very low or no juvenile recruitment onto shallow rocky 

outcrops in the Santa Barbara Channel. This suggests 

that dispersal of benthic stages plays a critical role in the 

dynamics of reef fish communities and local temperature 

may be an important criterion in habitat selection. Some 

species important in the warm-temperate fish assemblage 

(e.g., kelp bass and opaleye) declined in abundance during the cold La Niña year of 1999. The response of reef 

fish communities to oceanographic regime shifts may be 

faster and less persistent than previously thought.

2. Deeper-water Platform Fish Assemblages: 31–224 m 

(103–739 ft.)

Except where noted, the following synopsis encompasses platforms Irene, Hidalgo, Harvest, Hermosa, Holly, 
3-6

RESULTS AND ANALYSES

3-7

RESULTS AND ANALYSES

The size distribution of fishes differed by habitat 

type. The midwater assemblages harbored few fishes 

over 20 cm (8 in.) long (Figure 3.4). Immature, mostly 

young-of-the-year rockfishes and young painted greenling dominated midwater depths. In addition, seaperches, 

blacksmith, and several less abundant species inhabited 

this zone. In contrast, older and larger rockfishes, lingcod, 

and several other benthic species, occupied the platform 

bottom habitat. Rockfishes also dominated the shell 

mounds. The size frequency of shell mound fishes tended 

to be intermediate between the two other habitats (Figure 

3.4). This apparent partitioning of different size modes 

0

50

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150

200

250

0–30

31–6061–90

91–120

121–150151–180181–210211–240

Number of Fishes per 100 

m2

Depth (m)

Figure 3.5. Density of young-of-the-year rockfishes observed 

from the Delta submersible, by depth, at all platforms surveyed, 1995–2001. Note that large numbers of these fishes 

were also observed by scuba divers in the shallower sections 

of the platforms.

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Figure 3.6. Density, with 

standard error bars, of all 

fishes in midwater (by 30 

m depth zones), bottom 

and shell mounds, at seven 

platforms, 1996–2001.

Among platforms, total fish densities typically fell 

within a relatively small range (Figure 3.6). In general, 

platforms furthest offshore and in deepest waters had 

somewhat lower fish densities than did those closer to 

shore in shallower waters. However, the absolute number 

of fishes around deeper water platforms may be greater 

than those in shallower waters, as deeper platforms are 

much larger than shallower water structures. 

2b. Midwater Assemblages

Findings at a Glance 

Platform midwaters are nursery grounds for rockfishes as well as for other marine fish species such as cabezon 

and painted greenling. The young-of-the-year of at least 15 

rockfish species inhabit these midwater habitats. 

Benthic settlement success is greatly influenced by 

oceanographic conditions. During our study, densities 

of young fishes varied greatly between years and platforms. Young-of-the-year rockfish densities often varied 

100

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 80

25

50

75

100

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75

25

50

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Irene Hidalgo

Harvest Hermosa

Grace

Gail

Holly

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Figure 3.4. Frequency of occurrence of fishes in 5 cm size 

classes in midwater, bottom and shell mounds at seven 

platforms, 1996–2001. 

was most evident in the deepest platforms. Around shallow platforms, there was significant settlement of youngof-the-year rockfishes both in the midwater and at the 

bottom. This common feature blurred the distinctions 

between these two habitats. 

Young-of-the-year rockfishes showed strong depth 

preferences around platforms (Figure 3.5). Young-of-theyear were often very abundant in the shallowest portions 

(above 30 m, 100 ft., depths) of the platform but were 

also abundant between 31 and 120 m depths (102–396 

ft.). They were most abundant at depths between 61 and 

90 m (201–297 ft.).
3-8

RESULTS AND ANALYSES

3-9

RESULTS AND ANALYSES

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Figure 3.9. Density of all young-of-the-year bocaccio and widow rockfish and all YOY rockfishes combined in platform midwaters, by year and platform, 1996–2001. 

by a factor of 10 or even 100 among survey years at some 

platforms. From 1996 through 1998, rockfish settlement 

was generally higher around the platforms north of Point 

Conception compared to those structures in the Santa 

Barbara Channel, reflective of generally colder, more 

productive waters in central California. Colder waters 

in 1999 were associated with relatively high densities of 

young-of-the-year rockfish recruitment at all of the plat-

forms surveyed. In 2000 and 2001, rockfish recruitment at 

platforms in the Santa Barbara Channel remained higher 

than pre-1999 levels. We hypothesize that this was related 

to the oceanographic regime shift to cooler temperatures 

that may be occurring in southern California. 

Depending on platform location, we observed be-

tween 13 and 29 fish species in the midwater habitats 

below 31 m (102 ft.) depths (Appendix 3). There was no 

relationship between platform bottom depth and either 

the number of species or species diversity in the midwater 

habitat (Figures 3.7 and 3.8). Relatively abundant nonrockfish species included blacksmith, sharpnose seaperch, 

and juvenile painted greenling. Occasionally, we observed 

influxes of migratory species such as Pacific sardine, jack 

mackerel, and Pacific mackerel. However, because our sur-

veys are snapshots in time, they do not adequately capture 

the importance of platform habitats to these and other 

pelagic species. The most abundant fishes were youngof-the-year and older juvenile rockfishes and blacksmith. 

These are planktivorous and thus are not dependent on 

the platform for food. They utilize these structures for 

orientation in the water column and as refuge from pre-

dation. Less common species, such as seaperches, painted 

greenling, opaleye, and cabezon do feed on animals or 

algae living on the platform jacket or conductors.

Our research shows that oil and gas platforms off 

California provide important nursery grounds for many 

species of rockfishes. The most conspicuous faunal char-

acteristic of the platform midwaters below scuba depth 

is the dominance of young rockfishes. Over the course of 

the study, young-of-the-year and older juvenile rockfishes 

almost always comprised more than 90% of all fishes 

observed in this habitat (Appendix 3). In some years, 

young-of-the-year rockfishes were virtually the only fishes 

present at some platform midwaters (Appendix 3). 

The young-of-the-year of at least 16 rockfish spe-

cies (bank, blue, copper, darkblotched, flag, gopher, kelp, 

olive, pygmy, shortbelly, squarespot, widow, yellowtail 

rockfishes, bocaccio, cowcod, and one or more members 

of the subgenus Sebastomus) recruited to the midwater 

habitat. Many of the species that were most abundant (e. 

g., blue, olive, pygmy, squarespot, widow, and yellowtail 

rockfishes and bocaccio) are those that are epibenthic or 

semipelagic as adults. Of these diverse young rockfishes, 

widow rockfishes were consistently the most abundant 

species at platforms. Among adult rockfishes, kelp and 

whitespeckled rockfishes were commonly observed.

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Platform Midwater

Species Diversity

Figure 3.8. Species diversity of fishes in the midwaters of 

seven platforms, 1996–2001. Platforms are listed from left 

to right, from shallowest to deepest.

40

30

20

100

Holly

Irene

Grace

Hidalgo

Hermosa

Harvest

Gail

Number of Species

Platform

Platform Midwater

Number of Species

Figure 3.7. Number of species observed in the midwaters of 

seven platforms, 1996–2001. Platforms are listed from left 

to right, from shallowest to deepest.
Youriy-ofthe-Year Rocucdo

1999

U -

P1. Conception

Son Miguel k1iid

Santo Cruz Island

Anopo Island

3-10

RESULTS AND ANALYSES

3-11

RESULTS AND ANALYSES

Young-of-the-year and 1-yr old rockfishes of many 

species (e.g., bank, blue, olive, pygmy, shortbelly, squarespot, widow, and yellowtail rockfishes, and bocaccio) 

often formed highly mobile schools in the midwater 

habitat. During years of high abundance, these schools 

contained many thousands of individuals. Our experience suggests that these schools remained either inside 

the platform or ventured only a few meters outside it. 

Schools of young rockfishestended to more closely associate with the jacket substrate during years of low recruitment or when water visibility was poor. However, when 

their numbers were high or water clarity was good, young 

rockfishes, while still living within the platform structure, 

only loosely associated with the crossbeams and vertical 

structure. In general, the schools occurred throughout 

50 to 100 m or more (150–300 ft.) of the water column. 

Young copper, gopher, kelp, and flag rockfishes, treefish, 

and cowcod, as well as cabezon and painted greenling 

were generally observed either as solitary individuals or 

in small groups, usually intimately associated with the 

platform jacket. 

Young-of-the-year rockfish settlement (recruitment) 

to midwater habitats is also strongly influenced by oceanographic conditions. The density of these fishes varied 

greatly inter-annually by location and among platforms 

(Figure 3.9). Spatial and temporal differences in youngof-the-year rockfish densities often varied by a factor of 

10 or even 100. In several instances, a species that was 

entirely absent from a platform midwater in one year 

would recruit in great numbers in the following year. Between 1996 and 1998, young-of-the-year rockfish recruitment was generally higher around the platforms north 

of Point Conception in the Santa Maria Basin (Irene, 

Hidalgo, Harvest, and Hermosa) than at the structures 

in the Santa Barbara Channel (Holly, Grace, and Gail) 

(Figure 3.9). In contrast, these three years were a period 

of low rockfish recruitment for many species south of 

Point Conception both at platforms (Holly, Grace, and 

Gail) and natural outcrops. The colder water conditions 

of 1999 brought with it widespread recruitment for a 

number of rockfish species in California compared to 

the previous decades. This was reflected at all of the 

platforms surveyed (Figure 3.9). We should note that 

the 2000 data at Platforms A, B, C, Hillhouse, Hogan, 

Houchin, and Henry (see sidebar) strongly suggest that 

recruitment for some rockfish species, particularly blue 

and widow rockfishes, had been very successful in 1999.

In 2000 and 2001, recruitment of some rockfish at Platforms Gail and Grace remained higher than pre-1999 

levels (Figure 3.9). We hypothesize that this represents a 

successful response to the oceanographic regime shift to 

cooler temperatures that may be occurring in southern 

California and the greater northeast Pacific. 

The population dynamics of bocaccio exemplifies the 

annual and geographic variability that occurs in rockfish 

recruitment at both platforms (Figure 3.9) and natural 

outcrops (Figure 3.10). Prior to 1999, young-of-the-year 

bocaccio were absent at the platforms we surveyed (except 

Irene in 1996 and 1997). During 1999, large densities of 

young-of-the-year bocaccio were observed at Platforms 

Irene and Grace; small numbers of at least a few individuals were observed at most other platforms. Platform 

Grace provided the most striking example of inter-annual 

variability. Almost no young-of-the-year bocaccio were 

observed at Platform Grace prior to 1999. In contrast, during 1999, the platform harbored the third highest densities 

(after 1996 and 1999 at Platform Irene) of young bocaccio 

we observed around either platforms or natural outcrops 

during the six years of research. It is important to realize 

that even in years of relatively high rockfish recruitment, 

the actual process of settlement may result in a patchy 

distribution of young-of-the-year benthic recruits. Such 

patchiness was observed in the bocaccio recruitment 

pattern in 1999 at Platforms Grace and Gail, which are 

located only 8 km (5 miles) apart. While Platform Grace 

harbored large numbers of young bocaccio, they were 

much less abundant at nearby Platform Gail. Furthermore, our research has shown that successful rockfish 

recruitment at platforms does not always translate to 

similar high densities of these species at nearby natural 

outcrops. Using the Delta, in 1999 we also surveyed 12 

natural outcrops located in depths suitable for bocaccio 

recruitment and found little evidence of bocaccio recruitment over any of these structures (Figure 3.10).

In 2000, we studied the midwater habitats of 

Platforms C, B, A, Hillhouse, Henry, Houchin, Hogan, 

and Habitat. These platforms, located off Summerland 

east of Santa Barbara (Figure 1.1), were home to many 

typical midwater reef fishes, including juvenile blue, 

olive, and widow rockfishes (of the 1999 year class), 

blacksmith, kelp rockfish, kelp bass, painted greenling, 

halfmoon, and sharpnose seaperch. Unlike the species 

assemblage of the further offshore and the more northerly platforms, both garibaldi and California sheephead 

were common. In 1998, we surveyed Platform Edith 

and again found a typical mix of reef fishes, including blacksmith, halfmoon, opaleye, sheephead, and 

garibaldi. Complete species assemblages for all of these 

platforms are found in Appendix 3.

Figure 3.10. Patterns of young-of-the-year (YOY) bocaccio settlement in 1999, as observed from the Delta submersible surveys.

Pacific sardines, midwaters of Plaform Holly. Young-of-the-year yellowtail rockfish, midwaters of 

Platform Irene.

Juvenile bocaccio and widow rockfish, midwaters of 

Platform Grace.

DAN DUGANRICK STARR

MARY NISHIMOTO
3-12

RESULTS AND ANALYSES

3-13

RESULTS AND ANALYSES

2c. Bottom Assemblages

Findings at a Glance

The bottom habitat of platforms is dominated 

by subadult and adult rockfishes. Young-of-the-year 

rockfishes were also abundant around some platform 

bottoms, occasionally in large numbers. In general, 

more than 90% of all the fishes found around platform 

bottoms were rockfishes. The numbers and estimated 

densities of all fishes in the bottom habitats are shown 

by platform in Appendix 3. Bottom depth strongly influenced the number of species, species diversity, and 

density of fishes living around platform bases. This is 

in direct contrast to the midwater habitat. The presence 

of young-of-the-year and older aged juveniles indicates 

that the bottom habitat of some platforms may be important nursery habitat for some species. The platform 

base appears to be important to many marine species, 

as it provides both refuge and prey.

Depth strongly influences fish assemblages in platform bottom habitat. Species richness varied widely from 

about 33 species at Platform Holly to 17 species at Platform Harvest. Generally, the shallower-water platforms 

harbored more species than platforms in deeper depths 

although this trend may have begun to reverse at Gail, 

the deepest platform (Figure 3.11). Species diversity was 

high at the shallowest and deepest platforms and lowest 

among the mid-depth structures (Figure 3.12). Conversely, 

overall fish densities were much higher at the mid-depth 

platforms than at the deepest platforms (Figure 3.13). 

Diversity and abundance patterns were driven by 

the depth preferences of a suite of rockfishes that dominate the bottom habitats. For instance, brown, calico, 

copper, and vermilion rockfishes were most abundant 

around the shallower structures but were absent from 

the deepest platforms (Figure 3.13). Pile perch, painted 

greenling, and young-of-the-year lingcod displayed the 

same pattern. Juvenile lingcod were also abundant at 

the shallowest platforms, particularly at Platform Irene, 

but these were also occasional around even the deepest structures surveyed. Halfbanded rockfish and flag 

rockfish were typically found at the intermediate-depth 

platforms. Greenblotched, greenspotted, greenstriped, 

pinkrose, and stripetail rockfishes were most abundant 

around the deeper structures (Figure 3.13). The juveniles 

of many of these species were found in shallower water 

or on the shell mounds.

Platform structure in the bottom habitats may influence the distribution of fishes. This habitat encompasses 

that area where the platform jacket and conductors physically meet the seafloor. At all of the platforms surveyed, 

there is a crossbeam that rests on, or is close to, the bottom. Some portions of this crossbeam may be completely 

buried by sediment or undercut by currents. The platform jacket and, in particular, the undercut crossbeam, 

appears to provide many of the attributes of a natural 

outcrop, providing high relief and large crevices. Many 

species, such as canary, flag, vermilion, and widow rock40

30

20

10

0

Holly

Irene

Grace

Hidalgo

Hermosa

Harvest

Gail

Number of Species

Platform Bottom

Number of Species

Figure 3.11. Number of species observed at the bottom of 

seven platforms, 1996–2001. Platforms are listed from left 

to right, from shallowest to deepest.

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Species Diversity

Figure 3.12. Diversity of fishes at the bottom of seven platforms, 1996–2001. Platforms are listed from left to right, 

from shallowest to deepest.

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All Fishes

Calico Rockfish

Brown

Rockfish

Vermilion

Rockfish

All Rockfishes Copper

Rockfish

Pile Perch Painting Greenling

Halfbanded Rockfish

Greenspotted Rockfish Greenstriped Rockfish

Flag Rockfish

Lingcod

(juvenile)

Lingcod

(YOY)

Greenblotched

Rockfish

Pinkrose Rockfish

Figure 3.13. Densities (with standard error bars) of all fishes, all rockfishes and the most important species at the bottom of 

seven platforms, years combined, 1996–2001.
3-14

RESULTS AND ANALYSES

3-15

RESULTS AND ANALYSES

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3-16

RESULTS AND ANALYSES

3-17

RESULTS AND ANALYSES

fishes, bocaccio, pile perch, and painted 

greenling closely associate themselveswith 

the platform jacket, particularly with the 

crossbeam. Similarly, larger copper, 

greenspotted, greenblotched, and pinkrose 

rockfishes and cowcod tend to shelter inside or immediately next to the platform. 

These fishes were particularly abundant 

where a space formed between the lowest crossbeam and the seafloor. Calico 

and greenstriped rockfishes and various 

life stages of lingcod were less closely associated with the structure. While most 

species rarely ascend more than a meter 

or two above the seafloor, bocaccio and 

halfbanded rockfish often rose as much 

as 5 m (17 ft.) above the bottom. 

Most platform bottom species are either solitary or 

shelter in small groups. The exceptions are young-ofthe-year rockfishes, juvenile and subadult brown, copper, 

halfbanded, and vermilion rockfishes, and bocaccio. On 

a number of occasions, we observed aggregations of tens 

and hundreds of brown, copper, and vermilion rockfishes 

and bocaccio and large schools of halfbanded rockfish 

comprised of thousands of individuals.

Compared to midwater habitats, the fish species 

compositions at platform bottoms were relatively 

stable over time (Figures 3.14a, b). The dominant species varied little between years at any platform. Thus 

a platform, such as Gail, that was dominated by adult 

greenspotted and greenblotched rockfishes, bocaccio, 

and cowcod in one year tended to be inhabited by these 

same species in all years in about the same abundances. 

Similar patterns were observed for such common species as painted greenling (Platforms Irene and Holly), 

greenspotted rockfish (Platforms Hidalgo and Hermosa), 

copper rockfish (Platforms Irene and Holly), and flag 

rockfish (Platform Hidalgo). It is likely that we were 

observing some of the same individuals each year. This 

constancy would be expected as these assemblages are 

at least partially composed of subadult and adult stages 

of relatively sedentary and long-lived rockfishes. Thus, 

the composition of the bottom assemblages is not determined by the year-to-year fluctuations in year-class 

success that is characteristic of the platform midwaters. 

However, the densities of a few important species, particularly halfbanded rockfish, varied annually. In some 

years halfbanded rockfish were essentially absent from 

a platform bottom, only to be extremely abundant the 

following year. Schools of this species are highly mobile 

and may have been present but not in the vicinity of the 

submersible when the survey was made.

Our observations indicate that the bottom habitat of 

some platforms may be particularly important for certain 

species. For example, young-of-the-year lingcod densities 

were much higher at Platform Irene and Hidalgo than 

at any natural outcrop during any year of the survey 

(Appendix 4).

 Unlike most of the fishes living in the platform midwater, it is likely that the majority of the platform bottomdwelling species feed on platform-associated prey. Many of 

these species, such as brown, copper, and flag rockfishes, 

eat a variety of crustaceans, molluscs, and small fishes, 

many of which live in and around the jacket, conductors, 

and shell mound. Other species, such as lingcod, cowcod, 

and bocaccio are opportunistic feeders, preying on a very 

wide range of organisms, including benthic and water column fishes, molluscs, and crustaceans (Love et al. 2002). 

Thus, for many benthic fishes, the platform base provides 

not only shelter but also an abundant source of food.

We conducted one survey, in 1998, around the 

base of Platform Edith. We found that California 

scorpionfish, sharpnose seaperch, blacksmith, and 

blackeye goby were the most abundant species. See 

Appendix 3 for a complete species list.

2d. Shell Mound Assemblages

Findings at a Glance

Shell mounds support a rich and diverse fish assemblage. As at other platform habitats, rockfishes 

comprise the vast majority of the fishes. The many 

small sheltering sites created by mussels, anemones, 

and other invertebrates on the shell mounds provided 

structure in a habitat dominated by small fishes. Many 

of these fishes are the young-of-the-year and older-aged 

juveniles of lingcod and copper, flag, greenblotched, 

and pinkrose rockfishes and cowcod. The adults of 

these species inhabit the platform bottom.

Depending on platform, we observed between 17 

and 30 species living on this habitat. In the shell mound 

habitat, the patterns of species numbers, diversity, and 

fish densities were similar to those observed around the 

platform bottoms. Species numbers generally decreased 

with increasing depth (Figure 3.15) although it increased 

sharply at the Platform Gail, the deepest structure. This 

increase was due to the occurrence of a number of deeper 

water species (e. g., rex sole, blackgill rockfish, and California smoothtongue) that were absent from other platforms. 

As in the platform bottom habitat, species diversity was 

highest at the shallowest and deepest platforms compared 

to shell mounds in intermediate depths (Figure 3.16). 

The shell mounds surrounding all platforms provided habitat and refuge for a diverse assemblage of 

fishes. Fish densities were highest on the intermediatedepth platform shell mounds (Figure 3.17). However, as 

in the platform midwater and bottom, a majority of these 

fishes are rockfishes; between 53% and 98% of all fishes 

living on the shell mounds are rockfishes (Appendix 3). 

Furthermore, when highly migratory and non-resident 

species, such as Pacific hake and Pacific sardine, are 

eliminated from the analysis, rockfishes comprise more 

than 80% of the shell mound fauna at each of the seven 

platforms surveyed. Those species most characteristic 

of the shell mounds exhibited distinct depth preferences 

(Figure 3.17) and the abundance of some of these fishes 

was responsible for the higher densities in the intermediate bottom depths. The dominant species of the shallow 

water shell mounds were vermilion, copper, and calico 

rockfishes, young-of-the-year and immature lingcod, and 

painted greenling. A few species, such as greenspotted 

and halfbanded rockfishes, were most common in the intermediate bottom depths. It was primarily the very high 

densities of halfbanded rockfish that were responsible 

for the overall high densities at intermediate-depth shell 

mounds. Greenstriped, pinkrose, and stripetail rockfishes 

Bocaccio, bottom of Platform Gail. Subadult vermilion rockfish, bottom of Platform Grace.

Cowcod, bottom of Platform Gail. Lingcod, bottom of Platform Gail. MILTON LOVE

DONNA SCHROEDER

LINDA SNOOKMILTON LOVE

Mexican and greenspotted rockfishes, bottom of Platform Gail.

LINDA SNOOK
3-18

RESULTS AND ANALYSES

3-19

RESULTS AND ANALYSES

were most abundant at the deepest platforms surveyed.

The mosaic of small refuge sites created by mussels, 

anemones, and other invertebrates are occupied by small 

fishes. Many of these fishes are the juveniles of such species 

as lingcod and copper, flag, greenblotched, and pinkrose 

rockfishes and cowcod, whose adults inhabit the adjacent 

platform bottom. Small sheltering sites are rarely found at 

the platform bottom. In part, this explains why fishes tend 

to be smaller on a shell mound than on the associated plat-

form bottom (Table 2). This also explains why the shell 

mound assemblage so closely resembles its counterpart 

around the adjacent platform bottom. Painted greenling, 

calico, and halfbanded rockfishes, shortspine combfish, 

blackeye goby, and the poachers are among the dwarf spe-

cies occupying the shell mound. Juveniles of the species 

characteristic of platform midwaters, such as blue and 

widow rockfishes, are rare over the shell mounds.

Most shell mound species are solitary fishes, living 

just above the seafloor or nestled among the shell debris 

or around anemones, seastars, and other large inverte-

brates. The only schooling species is the halfbanded 

rockfish that often forms highly mobile schools of 100 

to 1,000 or more individuals.

It is likely that many of the fishes, including most of 

the rockfishes, combfishes, painted greenling, and other 

benthic species are resident to the shell mound habitat. 

Highly mobile and migratory species, such as northern 

anchovy, Pacific sardine, and juvenile Pacific hake, that 

were observed over the shell mounds probably spend only 

a relatively short period associated with this habitat.

Shell mound surveys were conducted around 

Platform Edith in 1998 and around Platform C in 

2000. Young vermilion rockfish, as well as halfbanded 

and calico rockfish, were the most abundant species 

around Platform C. These species were also characteristic of the shell mound at Platform Holly, which lies in 

a similar depth. California scorpionfish and blackeye 

goby dominated the shell mound around platform 

Edith. Edith lies a few miles southeast of Long Beach 

and near a known California scorpionfish spawning 

grounds (Love et al. 1987). California scorpionfish are 

relatively uncommon in the Santa Barbara Channel 

and are rare north of Point Conception. This distribu-

tion explains the near absence of this species from 

other shell mounds we surveyed.

40

30

20

100

Holly

Irene

Grace

Hidalgo

Hermosa

Harvest

Gail

Number of Species

Platform Shell Mound

Number of Species

Figure 3.15. Number of fish species observed on the shell 

mounds of seven platforms, 1996–2001. Platforms listed left 

to right from shallowest to deepest. 

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Species Diversity

Figure 3.16. Diversity of all fishes observed on the shell 

mounds of seven platforms, 1996–2001. Platforms are listed 

left to right from shallowest to deepest.

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All Fishes All Rockfishes Painted Greenling Copper Rockfish Calico Rockfish

Lingcod (YOY)

Stripetail

Rockfish

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(juvenile)

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Greenstriped Rockfish Pinkrose Rockfish Greenblotched

Rockfish

Figure 3.17. Density (with standard error bars) of all fishes, all rockfishes, and the most abundant shell mound fish species found around seven platforms, 1996–2001. Platforms are listed left to right from shallowest to deepest.
3-20

RESULTS AND ANALYSES

3-21

RESULTS AND ANALYSES

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HIDALGO 

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Figure 3.18. Locations of Platform Hidalgo and North Reef. Seafloor characterization by Gary Greene, Moss Landing 

Marine Laboratory.

96.6% of all fishes at Platform Hidalgo and North Reef, 

respectively. We observed a minimum of 34 fish species at each location. A few species were unique to each 

structure. Copper and stripetail rockfishes and California 

scorpionfish were found only at Platform Hidalgo, while 

blackeye goby, bluebarred prickleback, Pacific argentine, 

speckled sanddab, and an unidentified cuskeel were present only at North Reef. None of these species were major 

constituents of their respective fish communities.

However, when taking into consideration the fish 

assemblages of the three habitats (midwater, bottom, and 

shell mounds) at Platform Hidalgo, each was somewhat 

distinct from that of North Reef (Figure 3.19). To characterize and distinguish between the species assemblages 

at Platform Hidalgo and North Reef, we compared only 

the benthic assemblages of the platform bottom and 

shell mound and North Reef. Canonical discriminant 

analysis showed that species assemblages at the bottom 

of Platform Hidalgo and its shell mound were somewhat different from each other and from the North 

Reef assemblages (Figure 3.20a). The platform bottom 

assemblage was characterized by a suite of rockfishes, including bocaccio and cowcod, flag, vermilion, and widow 

rockfishes and lingcod. The shell mound assemblage was 

similar to and overlapped with the platform bottom, but 

was characterized by smaller fishes, such as swordspine, 

3. A Comparison of Fish Assemblages at a Deeper 

Platform and a Nearby Natural Outcrop: Hidalgo 

and North Reef 

Findings at a Glance

The species composition at Platform Hidalgo and 

North Reef are quite similar as both structures are dominated by rockfishes. In general, the distinctions between 

the platform and reef assemblages were based on differences in species densities (rather than species presence or 

absence). Most species were more abundant at Platform 

Hidalgo than at North Reef. Halfbanded, greenspotted, 

flag, greenstriped, and canary rockfishes, all three life 

stages of lingcod (young-of-the-year, immature, adult), 

and painted greenling all had higher densities around 

the platform. Five species (i. e., pink seaperch, shortspine 

combfish, pygmy, squarespot, and yellowtail rockfishes) 

were more abundant at the reef. The dominance of small 

fishes at North Reef probably reflects fishing pressure 

that has cropped larger individuals. Young-of-the-year 

rockfishes were found at both Platform Hidalgo (primarily in the midwaters) and at North Reef. In each of 

five years, young-of-the-year rockfish density was higher 

at the platform than at the reef. In several years, densities 

of these young fishes were more than 100 times greater 

at Platform Hidalgo than at North Reef. 

We surveyed the fish assemblages at Platform Hidalgo and a nearby natural outcrop, North Reef, for the period 1996–2001. North Reef was compared with Platform 

Hidalgo because it is close to the platform (about 1,000 

m, 3,300 ft., north of the platform) (Figure 3.18), and its 

depth (112 m, 370 ft.) is comparable to the platform’s 130 

m (430 ft.). North Reef is a hard carbonate scarp, which 

is 1–4 m (3–13 ft.) high, 3,353 m2 in area and contains 

numerous boulders, caves, and crevices.

The species composition at Platform Hidalgo and 

North Reef are very similar (Table 3). Both habitats are 

dominated by rockfishes; they comprised 98.3% and 

Pinkrose rockfish, shell mound of Platform Gail.

MILTON LOVE

Greenspotted and flag rockfishes, shell mound of Platform Gail.

MILTON LOVE

Young-of-the-year cowcod on shell mound of Platform Gail.

LOVELAB, UC SANTA BARBARA

Halfbanded rockfish, shell mound of Platform Hidalgo.

MILTON LOVE
3-22

RESULTS AND ANALYSES

3-23

RESULTS AND ANALYSES

4

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(juveniles)

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(YOY)

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(adults)

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Shortspine

Combfish

Pink

Seaperch

Yellowtail

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Rockfish

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Halfbanded

Rockfish

All fishes

(Platform

bottom only)

All fishes

(Platform bottom

and midwater)

Flag

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Greenspotted

Rockfish

Pygmy

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Figure 3.21. Mean densities (with standard error bars) of the common 

species or species assemblages at Platform Hidalgo and North Reef, 

1996–2001. Species or species assemblages are grouped by abundance.

5

-50

-505 10

Canonical Discriminant 1 (19.21%)

Canonical Discriminant 2

Platform Hidalgo

bottom

Platform Hidalgo

shell mound

Platform

Hidalgo

midwater

North Reef

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species

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Figure 3.20. 3.20a. Canonical Discriminant Analysis of fish 

assemblages at Platform Hidalgo bottom and shell mound 

habitats and North Reef, 1996–2001. Each yearly survey at 

North Reef was comprised of 2–3 transects and thus each 

year’s survey is represented by more than one cross. 3.20b. 

Canonical Discriminant Analysis of the species found 

around Platform Hidalgo, bottom and shell mound and 

North Reef, 1996–2001. Dots represent species that were not 

strongly associated with either axis.

Figure 3.19. Canonical Discriminant Analysis of fish as-

semblages at Platform Hidalgo, midwater, bottom, and shell 

mound habitats and North Reef, 1996–2001. 

greenstriped and halfbanded rockfishes, painted green-

ling, and juvenile lingcod (Figure 3.20b). 

In general, the distinctions between the platform and 

reef assemblages were based on differences in species 

densities rather than species presence and absence. The 

densities of a range of species varied between the two 

sites (Figure 3.21) and most exhibited higher densities 

at Platform Hidalgo than at North Reef (Figure 3.21). 

Halfbanded, greenspotted, flag, greenstriped, canary 

rockfishes, all three life stages of lingcod (young-ofthe-year, immature, adult), and painted greenling were 

among the species that were more abundant around the 

platform. Five species (pink seaperch, shortspine comb-

fish, pygmy, squarespot, and yellowtail rockfishes) were 

more abundant at the reef. 

Young-of-the-year rockfishes were common at both 

Platform Hidalgo (primarily in the midwaters) and at 

North Reef, although species differences were observed. 

From our submersible surveys, we identified at least seven 

species of young-of-the-year rockfishes at Hidalgo (e.g., 

blue, bocaccio, olive, pygmy, squarespot, widow, and yel-

lowtail). Our scuba surveys around that platform also noted 

young-of-the-year of the “copper complex,” composed of 

black-and-yellow, copper, gopher, and kelp rockfishes.Most 

of the young-of-the-year rockfishes at North Reef appeared 

to be pygmy, squarespot, and widow rockfishes.

The mean density of young-of-the-year rockfishes 

in the midwater habitat of Platform Hidalgo was higher 

than at North Reef (Figure 3.21). This probably reflects 

greater rockfish recruitment to the platform. This has 

important implications with respect to platform habitat 

values regarding settlement and fish production around 
3-24

RESULTS AND ANALYSES

3-25

RESULTS AND ANALYSES

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Figure 3.23. 3.23a. Canonical Discriminant Analysis of fish 

assemblages at seven platforms, bottom and shell mound, 

and all natural outcrops, 1996–2001. Each cross represents 

more than one natural outcrop. 3.23b. Canonical Discriminant Analysis of the species found at seven platforms, 

bottom and shell mounds, and all natural reefs, 1996–2001. 

Crosses represent species that were not strongly associated 

with either axis.

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Figure 3.22. Mean densities of young-of-the-year rockfishes, all species combined, at Platform 

Hidalgo midwater and North Reef, 1996–2001.

these structures. This recruitment pattern was repeated 

in each year of our surveys as young-of-the-year rockfish 

densities were always greater at the platform than at the 

outcrop (Figure 3.22). In some years, densities were more 

than 100 times greater at the platform. 

4. A Comparison of Fish Assemblages of Platforms 

and Natural Outcrops off Central and Southern 

California

Findings at a Glance

 Based on surveys of seven platforms and over 80 

natural outcrops, rockfishes dominate almost all of the 

platform and hard seafloor habitats. A greater number 

of species was observed at the natural outcrops (94) than 

at the platforms (85). There is a high degree of overlap 

in species composition and differences are primarily 

due to generally higher densities for more species at 

platforms.In particular, widow rockfish young-of-theyear, canary, copper, flag, greenblotched, greenspotted, 

greenstriped, halfbanded, and vermilion rockfishes, 

bocaccio, painted greenling and all life history stages 

of lingcod were more abundant at platforms. Yellowtail 

rockfish and the dwarf species pygmy, squarespot, and 

swordspine rockfishes were more abundant on natural 

outcrops. Some of these differences can be explained 

by recruitment (settlement) processes and the greater 

chance for survival at the platform habitats. We believe 

that as fish size increases with age the platforms act as 

de facto marine reserves because fishing pressure is 

light or nonexistent. Platforms can be characterized 

as having higher densities of young-of-the-year rockfishes than natural outcrops.

We compared the fish assemblages from the deeper 

parts of seven platforms (below about 30 m, 100 ft.) with 

those of similar depth natural outcrops. Analyses were 

based on platform surveys and on 133 dives at over 80 

natural outcrops throughout southern California and off 

Point Conception and Point Arguello (Figure 1.5).

We observed at least 85 species at platforms and 94 

species at outcrops (Table 4). Rockfishes dominated both 

habitats, comprising 89.7% of all fishes at platforms and 

92.5% at outcrops. Platform fish assemblages were somewhat different from those of natural outcrops (Figures 

3.23a, b). However, these differences were due almost 

entirely to the generally greater numbers, of more species, of fishes around platforms, rather than differences in 

species composition between platforms and outcrops. 

There was a distinct assemblage of fishes at the two 

shallow platforms, Holly and Irene, and another composed of species occupying the deeper platforms. Differences among platform bottom assemblages were more 

extreme than differences among shell mounds. This, 

too, was largely a function of greater fish abundance 

around platform bottoms than over the shell mounds. 

Intermediate-depth and deepest platforms were less 

distinct from each other than from shallow platforms. 

With or without the two shallow platforms (Holly and 

Irene) in our comparative analysis, the fish assemblages 

at the platforms still tended to be different from those 

at the natural outcrops (Figures 3.24a, b). These differences were primarily due to most fish species being more 

abundant at platforms than at outcrops (Figure 3.25). 

Widow rockfish young-of-the-year, canary, copper, flag, 

greenblotched, greenspotted, greenstriped, halfbanded, 

and vermilion rockfishes, bocaccio, painted greenling, 

and all life history stages of lingcod were more abundant 

at platforms. Species that were more abundant at natural outcrops than platforms included pygmy, squarespot, 

swordspine, and yellowtail rockfishes. 

Platforms tended to harbor higher densities of youngof-the-year rockfishes than did natural outcrops. Youngof-the-year rockfishes primarily occurred in the platform 

midwaters. Thirteen of the 20 highest young-of-the-year 

rockfish densities were observed at Platforms Grace, Harvest, Hermosa, Hidalgo, Holly, and Irene (Table 5). The 

highest young-of-the-year rockfish densities over natural 

outcrops were usually at high relief sites well away from 

the mainland. The California Current, which is centered 
3-26

RESULTS AND ANALYSES

3-27

RESULTS AND ANALYSES

0

10

20

30

40

50

60

70

80

90

100

Copper Rockfish

Lingcod (YOY)

Painted Greenling

Flag Rockfish

Halfbanded Rockfish

Vermilion Rockfish

Bocaccio (YOY)

Greenstriped Rockfish

Lingcod (Juvenile)

Greenspotted Rockfish

Lingcod (Adult)

Greenblotched Rockfish

Widow Rockfish (YOY)

Canary Rockfish

Bocaccio (Juvenile)

Pink Perch

Bocaccio (Adult)

Squarespot Rockfish

Yellowtail Rockfish (Adult)

Pygmy Rockfish

Swordspine Rockfish

Percent of Top 20 Sites

Platform Reef

Figure 3.25. The relative importance of seven platforms (Irene, Hidalgo, Harvest, Hermosa, Holly, Grace, and Gail) and about 

80 natural outcrops off central and southern California as habitat for common reef fish species. Densities of these species were 

computed for each year, at each location (platform midwater, bottom and shell mound, and natural outcrops) and ranked 

from highest to lowest. This figure displays the percentage that platforms or natural outcrops comprised of the top 20 densities for each species (or species’ life history stage). For example, of all sites where copper rockfish were observed, the highest 20 

densities were at various platforms, in a number of years. Similarly, the highest 20 densities of swordspine rockfish were all at 

natural outcrops. See Appendix 4 for underlying data.

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Figure 3.24. 3.24a. Canonical Discriminant Analysis of fish 

assemblages at five platforms (shallower platforms Holly 

and Irene deleted), bottom and shell mound, and all natural outcrops, 1996–2001. Each cross represents more than 

one natural outcrop. 3.24b. Canonical Discriminant Analysis of the species found at five platforms (shallower platforms Holly and Irene deleted), bottom and shell mound, 

and all natural outcrops, 1996–2001. Crosses represent 

species that were not strongly associated with either axis.

offshore of the coastal shelf, influences these locations 

(e.g., San Nicolas and San Miguel islands) more than the 

mainland sites we surveyed. Furthermore, our observations strongly imply that the midwaters of many platforms 

bear a striking resemblance to some of the relatively shallow and steep-sided outcrops (such as those on Hidden 

Reef) that dot the outer continental shelf of southern 

California. In both cases, the assemblages are dominated 

by young rockfishes and larger fish predators are relatively 

uncommon. Thus, survivorship of young fishes may be 

higher in both habitats due to lowered predation rates.

The role that some platforms play as defacto marine 

refuges is supported by evidence of greater densities of 

rockfishes, particularly the larger size classes, at platforms 

compared to natural outcrops. As an example, densities 

tended to be higher at some platforms than at natural 

outcrops for: (1) all rockfishes regardless of size, (2) all 

rockfishes greater than or equal to 30 cm (12 in.), (3) 

adult bocaccio, and (4) adult cowcod (Figures 3.26–3.29). 

Our experience is that rockfishes are most susceptible to 

being caught by both recreational and commercial gear 

when they reach about 30 cm (12 in.); thus, densities of 

fishes of this or larger sizes would be an indication of fishing pressure. Adult bocaccio and cowcod are overfished 

species with population sizes at levels less than 10% of 

unfished stock. These fishes at one time were abundant 

in southern California.

Rockfishes were observed at all of the platforms 

and outcrops we surveyed, with the exception of two 

sites on Piggy Bank (Figure 3.26). The highest rockfish 

densities (500 rockfishes or more per 100 m2) occurred 

at four platforms and at five natural outcrops; all of these 

structures were nursery grounds for young-of-the-year 

rockfishes. The assemblages of most of the other platforms and outcrops that harbored relatively high rockfish 

densities also were primarily composed of small rockfishes, both immature individuals and dwarf species. This 

can be clearly seen when we focussed on rockfishes 30 

cm (12 in.) or larger (Figure 3.27). The paucity of rockfishes 30 cm (12 in.) or larger is evident even at the most 

productive sites (Figure 3.27). Highest densities of large 

rockfishes (10 rockfishes or more per 100 m2) occurred 

at three platforms and two natural outcrops. Many sites 

harbored no or only a few larger rockfishes. 

Almost all of the natural outcrops we studied should 

have harbored large numbers of larger rockfishes. Their 

absence or rarity is almost certainly attributable at least 

in part to fishing pressure. These sites were comprised of 

boulders or other structures that were suitable shelter sites 

for larger sized rockfishes. A few outcrops, such as sites near 

the Potato and Osborn Banks, were composed of cobble, a 

habitat that is less likely to harbor large rockfishes. Adult 

bocaccio were only abundant around Platform Gail and 

were relatively common at Platform Hidalgo, Reef “D” 

near that platform and a few sites around the northern 

Channel Islands (Figure 3.28). Even at these natural outcrops, many shelter structures contained no or few adult 

bocaccio. Cowcod densities were also depressed (Figure 

3.29). Relatively few rock outcrops surveyed contained 

adults, and platform Gail harbored the highest densities, 

although even here numbers were low. In general, the 

highest densities of adult bocaccio and cowcod occurred 

at platforms or at those outcrops that were protected from 

harvest by distance from ports or by being situated in areas 

susceptible to poor weather conditions.
3-28

RESULTS AND ANALYSES

3-29

RESULTS AND ANALYSES

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Figure 3.26 . Density of all rockfishes, regardless of size, as observed from the Delta submersible on platforms and natural outcrops, 1995–2001. Fish densities for Platforms Irene, Hidalgo, Harvest, Hermosa, Holly, Grace and Gail, North Reef and reefs “A”, “B”, “C” and “D” in the vicinity of Platform Hidalgo represent means of years.

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Figure 3.27. Density of all rockfishes larger than or equal to 30 cm as observed from the Delta submersible on platforms and natural outcrops, 1995–2001. Fish densities for Platforms Irene, Hidalgo, Harvest, Hermosa, Holly, Grace and Gail are from platform bottoms and densities for these seven platforms and for North Reef and reefs “A”, “B”, “C” and “D” in the vicinity of Platform Hidalgo represent means of years. Platforms C, B, A, Hillhouse, Hogan, Houchin, and Henry were not included because they were not completely surveyed.
3-30

RESULTS AND ANALYSES

3-31

RESULTS AND ANALYSES

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Figure 3.28. Density of adult bocaccio (defined as fish larger than 35 cm total length) as observed from the Delta submersible on platforms and natural outcrops, 1995–2001. Bocaccio densities for Platforms Irene, Hidalgo, Harvest, Hermosa, Holly, Grace and Gail are from platform bottoms and densities for these seven platforms and for North Reef and reefs “A”, “B”, “C” and “D” in the vicinity of Platform Hidalgo represent means of years. Platforms C, B, A, Hillhouse, Hogan, Houchin, and Henry were not included because they were not completely surveyed.

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Figure 3.29. Density of adult cowcod (defined as fish larger than 45 cm TL) as observed from the Delta submersible on platforms and natural outcrops, 1995–2001. Cowcod densities for Platforms Irene, Hidalgo, Harvest, Hermosa, Holly, Grace and Gai are from platform bottoms and densities for these seven platforms and for North Reef and reefs “A”, “B”, “C” and “D” in the vicinity of Platform Hidalgo represent means of years. Platforms C, B, A, Hillhouse, Hogan, Houchin, and Henry were not included because they were not completely surveyed.
3-32

RESULTS AND ANALYSES

3-33

RESULTS AND ANALYSES

Why platforms support higher densities of young rockfishes than do nearby natural outcrops. 

Platforms are important nursery habitat for many species of rockfishes. This research demonstrates that, in general, platforms may be more important nursery habitats than nearby natural outcrops or, indeed, most other outcrops 

surveyed in central and southern California. Why is this? First, platforms occupy more of the water column than do 

most natural outcrops. Presettlement juvenile rockfishes, swimming in the midwater, are much more likely to encounter 

these tall structures than the relatively low-lying natural rock outcrops. It is interesting to note that most of the natural 

outcrops we found that had high densities of young-of-the-year rockfishes (e.g., Hidden Reef and outcrops around 

islands) were very high relief features that thrust their way well into the water column. 

In addition, there are also relatively fewer large predators in the platform midwaters. By comparison, even on 

heavily fished outcrops there tend to be at least a few larger fishes. Many of the major predators of young rockfishes 

are species that live close to the bottom, such as lingcod, copper and vermilion rockfishes, cowcod and large bocaccio. 

In general, these species do not ascend the platform jacket. Thus, even when they are abundant at the bottom of a 

platform, they are absent from the platform midwaters. In this respect, platforms are similar to some of the offshore 

pinnacles on the southern California continental shelf. Predatory species, such as cowcod, lingcod, and greenblotched 

rockfishes are also not abundant around the steep, smooth sides of offshore outcrops.

At most of the platforms, we observed both harbor seals and California sea lions, both resting on the platforms 

and swimming in the water column among the jackets and conductors. Based on the known food habits of these 

animals, it is likely that they feed on platform fishes, but their low numbers probably have little effect on the abundance 

of young rockfishes. We also observed both harbor seals and California sea lions swimming over natural outcrops and 

it likely that here, too, predation on young rockfishes occurs.

Platforms as defacto marine refuges

The role that some platforms play as defacto marine refuges is supported by evidence of greater densities of 

rockfishes, particularly the larger size classes, at platforms than at natural outcrops. The role that platforms may play 

as de facto reserves should not be underestimated at a time when many fish populations are in decline on natural 

outcrops. A number of benthic fishes, including such economically important species as bocaccio, cowcod, copper, 

and vermilion rockfishes and lingcod find refuge within the platforms and this is probably a factor in their relatively 

high densities compared to most natural outcrops. Schroeder and Love (2002) compared the rockfish assemblages at 

three deeper-water areas subjected to variable fishing pressures. Two were natural outcrops, one outcrop open to all 

fishing and one open only to recreational fishing, and the third was Platform Gail, acting as a de facto marine refuge. 

The outcrop allowing open fishing had the highest densities of rockfishes (7,212 fish/ha); however, the assemblage 

was dominated by dwarf species. The recreational fishing area had the lowest rockfish density (423 fish/ha) and this 

assemblage was also dominated by small fishes. Platform Gail possessed a relatively high density (5,635 fish/ha), and 

the fishes tended to be larger than individuals at either of the fished sites. Two federally listed overfished species, 

cowcod and bocaccio, had 32- and 408-fold higher densities, respectively, at Platform Gail than the recreational site, 

and 8- and 18-fold higher densities, respectively, than the all-fishing area.

There is some fishing effort around most platforms in the Southern California Bight and Santa Maria Basin. The 

relative amount of fish pressure among platforms is dependent on ease of access and local ocean conditions. Platforms 

in the Santa Maria Basin are located in an area that is far from ports, usually windy, and unprotected from weather. It 

is difficult to fish around the bottom of platforms, especially the deeper ones, because of the threat to gear imposed 

by the large number of crossbeams, other platform structural elements, conductors, and strong currents. Many anglers 

also believe that operators do not welcome fishing near their platforms. 

Some platforms are important fishing areas for recreational anglers. Historically, commercial passenger fishing 

vessels and small private vessels fished around some of the shallower platforms in the Santa Barbara Channel (Love 

and Westphal 1990). Platforms Hilda and Hazel were targeted for kelp bass. During years with strong rockfish recruitment, large numbers of juvenile bocaccio, blue, olive, and widow rockfishes were caught at Platforms Holly, A, B, C 

and Hillhouse. In all of these instances, fishing effort was directed at surface or midwaters, rather than at the platform 

bottom. The removal of Hilda and Hazel and the poor rockfish recruitment of the 1980s and much of the 1990s 

reduced the overall fishing effort at oil/gas platforms. Some recreational fishing continues around Platform Gina, and 

there is minimal effort around a few other structures in the Santa Barbara Channel.

Overfishing has drastically altered the species composition of many outcrops off central and southern California 

(Yoklavich et al. 2000; M. Love, unpublished data). Over most moderate-depth and deep outcrops in central and southern California, many, or sometimes all, of the larger predatory fishes, such as lingcod, cowcod, bocaccio, yelloweye, 

and canary rockfishes are gone. In contrast, surveys made over an unfished outcrop in central California showed very 

high densities of large predatory fishes, including lingcod, cowcod, bocaccio, and yelloweye rockfish (Yoklavich et al. 

2000). At many natural outcrops, these larger individuals have been replaced by very large numbers of dwarf species, 

particularly pygmy, swordspine, and squarespot rockfishes. Fish assemblages at platforms, such as Gail, Hidalgo, and 

Irene, with relatively high densities of many economically important species and low numbers of dwarf species, may 

more closely resemble unfished assemblages than those at many natural outcrops.

Bocaccio.

LOVELAB, UC SANTA BARBARA
Larva

Pelagic

Juvenile

Adult

Benthic

Juvenile

3-34

RESULTS AND ANALYSES

3-35

RESULTS AND ANALYSES

Figure 3.30. A typical rockfish life history cycle using the cowcod as an example.

5. The Origins of Platform Fishes: Production and 

Attraction

Finding at a Glance 

Our research suggests that platforms, like natural 

outcrops, both produce and attract fishes, depending 

on species and location. Platform fish assemblages 

around the deeper and further offshore platforms 

may be generated primarily from the recruitment of 

larval and pelagic juvenile fishes, not from attraction 

of fishes from natural outcrops. Some fishes may live 

their entire lives around a single platform but their 

movement patterns are poorly known. A pilot study 

comparing growth rates showed that young-of-theyear blue rockfish grew faster at a platform than at a 

natural outcrop.

In recent years, public attention has been drawn to 

artificial reefs and their function in the marine environment. While a variety of issues have been raised, much 

of the discussion has centered around the question of 

whether artificial reefs are producers or attractors of 

marine life (Carr and Hixon 1997; Lindberg 1997). 

Some researchers suggest this question is biologically 

simplistic, because it “imposes an unrealistic either-ordichotomy...” (Lindberg 1997). Nevertheless, this issue 

continues to arise in the context of the importance of 

platforms as fish habitat off California (Carr and Stephens 1998; Krop 1998). 

Attraction suggests the net movement of juvenile 

and adult fishes away from natural outcrops to platforms. 

While there is not complete agreement on the definition 

of production, most researchers agree that it involves 

larval or pelagic juvenile settlement at a structure and 

the survival and growth of these organisms in this habitat (Carr and Hixon 1997).The attraction/production 

debate is framed around three questions (Carr and 

Stephens 1998; Krop 1998): (1) Do larval and juvenile 

fishes settle onto platforms from the plankton, or do 

fishes move from other structures to platforms as older 

juveniles or adults? (2) If a species does settle onto a 

platform, are growth and survivorship at least as good 

as on a natural outcrop? (3) If a species does grow and 

survive well around a platform, did the structure take 

away larvae or pelagic juveniles that would have settled 

onto natural outcrops?

5a. Do Fishes Settle from the Plankton onto Platforms or Do They Swim There from Other Structures 

as Juveniles or Adults?

A large number of fish species settled out of the 

plankton and took up residence around platforms. We 

observed young-of-the-year of about 46 fish species at 

these structures (Table 6) and, including species observed by other researchers (Carlisle et al. 1964), at least 

50 fish settle on to platforms from the plankton. During 

some years, the midwaters of many platforms had very 

high densities of juvenile rockfishes. Young-of-the-year 

blacksmith, kelp and painted greenlings, and cabezon 

also were abundant in this habitat at times. Young-ofthe-year rockfishes, lingcod, and other species were 

abundant around platform bottoms and shell mounds. 

With a few exceptions, species that settled on the bottom and shell mound were different from those found 

in the midwaters. 

Juveniles of some species were rarely or never observed around platforms. For instance, young-of-the-year 

kelp bass were rarely seen around any platform, although 

adults were very abundant at one platform. Young seaperches also were rare or absent. In these cases, older juveniles or adults immigrated to the platforms or juveniles 

settled there at times other than our surveys.

5b. The Biological Influence of Oceanographic 

Conditions on Recruitment Success at Platforms and 

Natural Outcrops in the Santa Barbara Channel and 

Santa Maria Basin 

Most coastal fishes and invertebrates, including those 

inhabiting platforms, are planktonic during early stages 

of their life histories. These life stages, which may last 

from weeks to months, can begin as fertilized eggs (e.g., 

lingcod, cabezon, and garibaldi) or larvae (e.g., rockfishes). Some fishes, including rockfishes, continue to 

develop in the pelagic environment until they transform 

to the juvenile stage (Figure 3.30).

Pelagic life stages are at risk from starvation and 

predation and transport away from the specific habitats 

required for their growth and survival. Therefore, the 

type of water mass an animal finds itself may have a 

profound effect on its survival. There are a number of 

water masses in our study area, including waters from the 

Southern California Bight, the central California coast, 

upwelling from Point Conception, and from more distant 

places such as Baja California. How these waters enter, 

circulate and mix in the Santa Barbara Channel and Santa 

Maria Basin affects marine populations and community 

diversity on both platforms and natural habitats.

Upwelling processes, the wind-induced pulling of 

deeper, colder water to the surface and displacement of 

warmer waters offshore, is a major factor in larval and 

pelagic juvenile survival. During years when upwelling 

coincides with larval fish production, fish survival may 

be enhanced. Because deep waters are nutrient-rich, 

upwelling increases reproduction of phytoplankton 

and encourages the growth of zooplankton, providing 

food for larval and pelagic juvenile fishes. Upwelling may 

also increase survivorship of some species by moving 

larvae and pelagic juveniles somewhat offshore, away 

from high densities of nearshore predators. Conversely, 

the offshore transport that accompanies upwelling can 

be detrimental to the survival of larvae and pelagic juveniles. Wind-induced turbulence in surface waters can 

make it difficult for larvae to come into contact with prey. 

Larvae risk being swept well offshore by strong upwelling and far removed from suitable habitat. Spatial and 

temporal variability in circulation, however, can provide 

some larvae and pelagic juveniles with conditions that 

enhance survivorship including delivery to optimum 

settlement. 

The timing, location, intensity, and duration of upwelling events may have a large effect on rockfish settlement. For instance, recruitment may be hampered at sites 

constantly exposed to newly upwelled water. Through 

much of the late-spring and summer when presettlement-stage rockfishes are in the pelagic environment, 

upwelling from the mainland at Point Conception impacts the west channel. Our summer oceanographic data 

confirm that the upwelling plume can extend across the 

western portion of the Northern Channel Islands (Love 

et al. 1999). We found that pelagic juvenile rockfishes 

were relatively rare in this newly upwelled water (Figure 3.31) (Nishimoto 2000). As an example, when cool 

upwelled waters moved into an area off the south side 
21

19

17

-21 -j -Il4 -IJ ø -1L1 -IIL&

3-36

RESULTS AND ANALYSES

3-37

RESULTS AND ANALYSES

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Figure 3.31. The abundance of late-larval stage and pelagic juvenile rockfishes decreases off the south side of Santa Cruz Island 

when one water mass replaced another between two sampling periods, June–July 1996. Temperature and salinity properties were 

used to identify four water masses: Upwelled water, Southside Island water, Northside Island water, and Southern California 

Bight water. Hauls are represented by colored circles. Fish abundance was estimated using the mean collected in midwater 

trawl hauls within a water mass. Bars illustrate the relative abundances among the water masses. Zeros indicate that no rockfishes were collected in the hauls within a water mass. 

Figure 3.32. The strong correspondence between exposure to 

cool water and young-of-the-year rockfish density. A shift in 

position of the thermal front on the north shore of Santa Cruz 

Island (SCI) in 1996 and 1997 corresponded with a striking 

spatial shift in juvenile rockfish densities (see sampling sites, 

Pelican Bay (PB) and Scorpion Anchorage (SA)). Numbers 

overlaid on images represent mean densities of juvenile 

rockfishes (number/60 m2) that recruited to giant kelp canopy 

at sites within the survey area.

Figure 3.33. The strong link between eddy circulation and 

the distribution of pelagic young-of-year rockfishes. A persistent eddy about 30 km (19 mi.) wide was evident in satellite 

sea surface temperature imagery and in surface current 

mapping generated from coastal-based high frequency radar 

observations. The abundance of fishes were extraordinarily 

high in the center of the eddy (red bars represent the mean 

number of late-stage larval and pelagic juvenile rockfishes in 

midwater trawl samples from different areas). 

of Santa Cruz Island, the fish assemblage changed from 

one with relatively abundant pelagic juvenile rockfishes 

to one where these fishes were almost absent. We suspect that the upwelled water, the coldest and most saline 

water mass that we identified, was recently brought to 

the surface from depths where few larval and juvenile 

rockfishes reside. 

Inter-annual oceanographic conditions, including 

the intensity of seasonal, coastal upwelling, are highly 

variable and this affects year class success and population 

variability. A shift from El Niño to La Niña conditions 

between 1998 and 1999 was marked by abrupt changes 

in the marine ecosystem off southern and central California. Our survey data of young-of-the-year rockfishes 

in 1999 indicates an increase in rockfish recruitment. 

The number of several juvenile rockfishes and other fish 

species observed on oil/gas production platforms and 

rocky outcrops in 1999 far exceeded those of 1998 and 

previous years. This increased recruitment coincided 

with intense coastal upwelling off Central California 

(among the strongest events in 50 years) in spring 1999 

followed by high phyto- and zooplankton production 

(Lynn et al. 1998; Hayward et al. 1999). High productivity in the region likely contributed to the increased 

survivorship of the fishes including those that recruited 

to the platforms and natural outcrops.

Relatively transitory phenomena, such as fronts and 

eddies, may also play an important role in fish settlement 

and year-class success. Fronts, the zones where different water masses collide and mix, may prevent weak-swimming 

planktonic animals from swimming between these masses 

(Moser and Smith 1993; Wing et al. 1998). The strength of 

recruitment to a platform or outcrop may be determined in 

part by the habitat’s exposure to those fronts carrying readyto-settle fish larvae and juveniles. Our research at Santa Cruz 

and Anacapa islands indicates that the recruitment of nearshore rockfishes was sparse on outcrops separated from cool, 

fish-rich waters by a frontal boundary (Figure 3.32) (Love, 

Nishimoto, Schroeder, and Caselle 1999). 

Eddies, cyclonic currents that can concentrate and 

retain plankton, may retain fishes and affect the dispersal 

of larval and juvenile fishes to outcrops and platforms. For 

instance, in summer 1998 we sampled a stationary and 

persistent cold-core cyclonic eddy in the western Santa 

Barbara Channel. In this feature, we found very high concentrations of small fishes, including late-stage larval and 

pelagic juvenile rockfishes (Figure 3.33).Eddies may also be 

very transitory. During the summer of 1999, we observed a 

much different circulation pattern of shorter-lived, propagating eddies and collected few young rockfishes. 

We suspect that the high levels of recruitment of 

young-of-the-year rockfishes at some platforms were associated, in part, with eddies and fronts retaining larvae 

that had been locally produced at either platforms or 

natural outcrops. For instance, Platform Irene is located 

to the north of the frontal boundary of the upwelling 

plume that extends off Point Conception. The platform 

is also situated in an area where a semi-persistent eddy 

is frequently observed during spring and summer 

(L.Washburn, personal communication). Similarly, both 

fronts and eddies were observed at Platforms Gail and 

Grace in the eastern channel north of Anacapa. As noted 

previously, Platform Gail harbors important habitat for 

adult bocaccio in the Santa Barbara Channel. Local retention of bocaccio larvae produced at Platform Gail would 

explain the high levels of bocaccio settlement at nearby 

platform Grace and Gilda. 

The variability of oceanographic conditions in the 

Santa Barbara Channel between 1995 and 2001 appears 

to have strongly influenced settlement as young-of-theyear recruitment to platforms and natural outcrops 

was highly variable both temporally and spatially. For 

instance, while the 1997–1998 El Niño corresponded with 

a large increase in juvenile recruitment of species that 

dominate the warm-temperate fish assemblage (such as 

blacksmith), the 1999 La Niña corresponded to a strong 

settlement of cool-temperate species, such as rockfishes. 

While settlement of many rockfish species to platforms 

was generally higher north of Point Conception than in 
3-38

RESULTS AND ANALYSES

3-39

RESULTS AND ANALYSES

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Figure 3.34. A comparison of daily growth rates of young-of-theyear blue rockfish collected at Platform Gilda and Naples Reef in 

1999. Fish from Platform Gilda grew at a statistically faster rate 

than did those from the natural outcrop.

Figure 3.35. Flag rockfish at the bottom of Platform Grace, 2001. These 

fish recruited to the platform as pelagic juveniles in 1999 and moved to 

the bottom in 2000.

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Figure 3.36. Size structure of young bocaccio observed at Platform Gail and flag rockfish observed at Platform Grace, 1996 to 

2001. Black line denotes persistence of the successful 1999 year class.

the Santa Barbara Channel during 1996 through 1998, 

the cooler waters of 1999 brought with it a relatively good 

year for cool-temperate rockfish recruitment throughout 

the channel.

The timing of this upsurge in young-of-the-year 

rockfish settlement in the Santa Barbara Channel also 

coincided with what may have been a Northeast Pacific 

oceanographic regime shift from warm to cool waters 

that overlaid the El Niño and La Niña events. This may 

have been reflected in the 2000 and 2001 rockfish recruitment at platforms in the eastern channel, which remained 

higher than pre-1999 levels. We should note that the last 

cold water regime off southern California occurred in the 1970s, a period that saw heavy 

settlement of young-of-the-year blue, olive, 

and widow rockfishes and bocaccio to some 

of the platforms near Santa Barbara (Love and 

Westphal 1990).

5c. If a Species Does Settle around a Platform, How Well Does It Grow and Survive, 

Particularly Compared to the Same Species 

on a Natural Outcrop?

While our studies in this area are preliminary, they are sufficiently compelling that we 

can begin to draw some conclusion regarding 

production of fishes at platforms. On many 

platforms, we believe that larval and pelagic juvenile recruitment is a major force in shaping 

platform fish assemblages. We have observed 

young-of-the-year of about 46 species at the 

platforms. Of these species, at least 35 were observed as 

adults at the same structures (Table 7). Adults of some 

species, such as pygmy, widow, and yellowtail rockfishes, 

are relatively uncommon around platforms suggesting 

different habitat requirements. Conversely, adults of 

many more species, including blacksmith, bocaccio, cabezon, cowcod, lingcod, painted greenling, shortspine 

and longspine combfishes, and calico, copper, flag, greenblotched, greenspotted, greenstriped, halfbanded, kelp, 

and pinkrose rockfishes are abundant at the platforms. 

Pilot research suggests that at least some juvenile 

fishes may be growing as well or better at the platforms 

than at natural outcrops. In 1999, we collected youngof-the-year blue rockfish from Platform Gilda and from 

Naples Reef (Figure 1.1). Daily growth rates derived from 

these fishes from otoliths (ear bones) indicated that the 

platform fish grew at a statistically faster rate than did those 

from the natural outcrop (F-test, F = 2.96, p = 0.0006) 

(Figure 3.34). 

Recruitment patterns of flag rockfish at Platform 

Grace and bocaccio at Platform Gail in 1999 and subsequent annual monitoring of year classes at these sites 

is providing important new information about the production value of platform habitats. In 2000, and again in 

2001, we observed the 1999 year classes of these species 

at the bottoms of the platforms (Figures 3.35 and 3.36). 

Length-frequency data indicate substantial survival of 

the 1999 year classes at the platforms (Figure 3.36). Flag 

rockfish mature at about six years of age (M. Love and 

M. Yoklavich, unpublished data) and bocaccio at four or 

five years (A. MacCall, personal communication). Thus, 

it is conceivable that these fishes will mature at the platforms. This would be strong evidence of production at 

these structures. [Added in proof: We again observed 

these fishes during our 2002 surveys of Platforms Gail 

and Grace.]

5d. Both Attraction and Production Play Important 

Roles in Shaping Fish Assemblages at Platforms

Our research suggests that populations of fishes at 

platforms far removed from natural outcrops, as is true 

for Platforms Gail and Grace, are most likely dependent 

on larval and juvenile recruitment from the plankton. 

Our research is developing information about recruitment and residence of fishes at platforms and we have 

provided evidence of fishes not only settling out at 

platforms but also maturing there. Recruitment process 

is highly variable at all habitats from year to year. Adult 

abundance, at least for some species, is dependent on the 

strength of recruitment in previous years. Furthermore, 

recruitment variability may contribute to the year class 

success (i.e., demographics) of platform and outcrop 

species such as flag rockfish and bocaccio.

While the movement patterns of some deeper-water 

rockfishes are unknown, it is likely that many benthic 

species, such as greenspotted, greenblotched, pinkrose, 

and cowcod are residential (Starr et al. 2001; Love et al. 

2002). Certainly many are restricted to hard substrata 

seafloors and probably rarely traverse large expanses of 

soft sediment (Love et al. 2002). Thus, it is likely that 

the high densities of many platform rockfishes, as well 

as such species as combfishes, painted greenling, and 

perhaps lingcod, are due to successful settlement from 

DONNA SCHROEDER
3-40

RESULTS AND ANALYSES

4-1

CHAPTER 4 

A GUIDE TO ECOLOGICAL AND 

POLITICAL ISSUES SURROUNDING 

OIL PLATFORM DECOMMISSIONING 

IN CALIFORNIA

Donna M. Schroeder and Milton S. Love

the plankton and subsequent survival. 

The shallow-water species that do inhabit offshore 

platforms are further evidence that larval and juvenile 

recruitment play a dominant role in these structures’ assemblages. Shallow species that do occur on Gail and/or 

Grace include kelp bass, garibaldi, and grass and kelp 

rockfishes. All of these fishes have pelagic larvae. Pile 

perch and rubberlip seaperch, species without a pelagic 

life stage, while found on the shallower platforms, are 

not present on Gail and Grace. This reflects the difficulty these species have in crossing deep waters along 

the seafloor. 

Thus, there is growing evidence that individuals of 

a number of species, particularly those that are relatively 

resident and benthic, not only settle out at platforms 

but also mature there. Such species include, but are not 

limited to, blacksmith, bocaccio, cowcod, flag, grass, 

greenblotched, greenspotted, kelp, pinkrose rockfishes, 

painted greenling, and combfishes. 

A dependence on pelagic juvenile recruitment, rather 

than attraction of older fishes from other structures, explains some of the differences in species composition we 

observed among the platforms. For instance, until 1999, 

we observed high densities of adult flag rockfish only at 

Platform Hidalgo. These densities were far higher than at 

other platforms or natural outcrops. In 1999, there was 

a strong recruitment of pelagic juvenile flag rockfish to 

Platform Grace, and as noted above, these fish remained 

there at least through 2001. [Added in proof: We observed 

these fish in 2002.] Annual recruitment of rockfish is 

highly variable. Thus, the large numbers of flag rockfish 

observed at Platform Hidalgo are almost certainly the 

result of a previous successful recruitment, similar to that 

at Platform Grace. Spatial variability is indicated by the 

paucity of this species at the other platforms. Similarly, 

the high densities of adult bocaccio at Platform Gail, 

and their absence at Platform Harvest (which is located 

in about the same depth), also suggests spatial variability 

in the recruitment process. 

In contrast, the fish assemblages at platforms that 

are closer to shore, and in shallow waters, are probably 

derived both from larval/pelagic juvenile settlement and 

movements of juveniles and adults from other structures. 

Carlisle et al. (1964) clearly demonstrated that inshore 

reef species, such as kelp bass and sheephead, are very 

mobile and able to traverse shallow, soft seafloors from 

outcrop to artificial reef. Platform Gina, for instance, is 

a shallow water platform that seasonally harbors very 

large numbers of kelp bass, halfmoon, opaleye, pile perch, 

and other reef species. Fishes are abundant around that 

platform during summer and fall, but move elsewhere 

in late winter and spring. 

Decommissioning Alternatives

Within one year of an OCS lease termination, the 

Minerals Management Service (MMS) requires that the 

lessee remove the oil platform structure to a depth of fifteen feet below the mud line, and the leased area must be 

cleared of obstructions (see generally, 30 C.F.R. Part 250, 

subpart Q, § 250.1700 et seq.). However, the MMS may 

waive these requirements to accommodate conversion 

of a platform structure to an artificial reef provided that 

(1) the remaining structure does not inhibit future oil 

or other mineral development, (2) the resulting artificial 

reef complies with the Army Corps of Engineers permit 

requirements and procedures outlined in the National 

Artificial Reef Plan, and (3) a state fishing management 

agency accepts liability for the remaining structure (30 

C.F.R. §§ 250.1703, 250.1730). In addition, the National 

Fishing Enhancement Act of 1984 (NFEA), which authorizes the Corps of Engineers’ permit program and 

the National Artificial Reef Plan (33 U.S.C. § 2101 et 

seq.), allows other organizations or agencies (such as 

the operator) to assume liability for the artificial reef, 

although MMS policy to date has required a state agency 

to accept liability. 

The timing of future decommissioning activities 

is not fixed. It depends on the length of the lease, the 

rate of reservoir depletion, the market value of oil or 

gas, and whether the platform might serve an extended 

use for the operator, such as a gathering system for the 

production of other platforms. There are three stages in 

the decommissioning process: planning, permitting, and 

implementation. Platform decommissioning alternatives 

fall into four general categories: complete removal (the 

default option), partial removal, toppling, and leave-inplace (Figure 4.1). The suite of decommissioning alternatives that proposes to leave part or all of the abandoned 

platform structure in the marine environment is often 

collectively referred to as “rigs-to-reefs”.

Alternative 1: COMPLETE REMOVAL

A typical full-removal project begins with well 

abandonment in which the well bores are filled with 

cement. The conductors are then separated from below 

the seafloor by being pulled, cut-off, or removed using 

explosives. Next the topsides, which contain the crew 

quarters and the oil and gas processing equipment, are 

cut from the jacket and removed. Finally, the piles that 

hold the jacket to the seabed are severed with explosives 

and the jacket is removed. Other typical decommissioning requirements include the removal or abandonment 

of pipelines and electrical cables and the removal of any 

debris from the seafloor. 

After deciding to totally remove a platform from 

the seafloor, operators have several options (O’Connor 

1999; van Voorst 1999; Gibbs 2000; Terdre 2000). (1) 

The platform can be taken to shore, where it is disassembled and the components either recycled, sold as 

scrap, or discarded in landfills or other depositories. 

To date, managers have selected this option for most 

decommissioned platforms. (2) The structure can be 

reconditioned and reused. As an example, in 1997 a 

platform was removed from the North Sea, taken to 

shore and cleaned, refurbished, shortened by 10 m (33 

ft.), and installed in another North Sea location. A few 

small platforms have also been reused in the Gulf of 

Mexico. (3) A platform can be towed to another site 

and reefed. This has occurred a number of times in the 

Gulf of Mexico, with the most zealous example towing 

structures of two Tenneco platforms over 1480 km (920 

mi) from offshore Louisiana to a site 1.5 miles off Dade 

County, Florida (Wilson et al. 1987). 

Alternative 2: PARTIAL REMOVAL

In this scenario, the wells are abandoned, the topsides 

are removed, and the remaining jacket and possibly the 

shell mound are left in place to continue to function as 

an artificial reef. Navigation aids are added.

Despite what has been implied in other reports, 

conductors need not be completely removed. Dauterive 

(2000) notes “Recognizing the preservation of environmental values associated with the method of partial 

removal of the platform, the MMS in 1997 established a 

policy to allow the industry the option to partially remove 

Adult canary rockfish at bottom of Platform Hidalgo.

MARY NISHIMOTO
Tpide 

ReUmed 

t 

Nc Removal 

-.: Topside 

Removed 

Enhance 

To.pide 

Removed 

No Enhancement 

California Platform Decommissioning Options 

Partial 

Removal 

Topple 

Move to 

Artificial Reef Site 

Removal from Original Site 

Removed to Onshore 5te 

(recydlrl9 and!o drspo.a1) 

ReLised at 

Another Site 

t 

Partial 

Removal 

Topsides recrove, reqcled or reirntalled, 

arid Jacket and Conductors left in place 

(5ubsrfce Structure) 

Top. Retain Wrticol ly 

Erthane No 

Enhancement 

Topple 

Na 

Enhan(emen 

4-2

DECOMMISSIONING OPTIONS AND ISSUES

4-3

DECOMMISSIONING OPTIONS AND ISSUES Figure 4.1. Platform decommissioning options.
4-4

DECOMMISSIONING OPTIONS AND ISSUES

4-5

DECOMMISSIONING OPTIONS AND ISSUES

Jacket and conductor removal: the role of the U. S. 

Coast Guard in decommissioning

Local United States Coast Guard districts are responsible for the safety of vessel traffic in their respective 

geographic areas and have the authority to dictate aids to 

navigation for obstacles in the water (14 U.S.C. §85; 43 

U.S.C. § 1333(d); 33 C.F.R. Part 67). Therefore, in instances where some part or all of a platform is to be reefed, the 

Coast Guard will specify the necessary navigational aids. 

Discussions regarding decommissioning of platforms off 

California have often erroneously assumed that the Coast 

Guard will require that the jacket be removed to about 

26 m (85 ft.) below the surface. However, decommissioning experience in the Gulf of Mexico demonstrates that 

there is no set removal depth. Indeed, the Coast Guard 

decision-making process appears to be quite flexible; it 

reviews each decommissioning on a case-by-case basis. 

For instance, in the decommissioning of the mile-long 

Freeport-McMoRan sulfur mine platform and bridge off 

Louisiana, the Coast Guard required piles to be cut 9 m 

(30 ft.) beneath the surface (Kasprzak 1999). 

Generally, the requirements for aids to navigation become more restrictive (and therefore more expensive) the 

closer to the surface the obstacle lies. As an example, here 

is a generic set of conditions for decommissioned platforms in the Gulf of Mexico based on recent Coast Guard 

decisions (G. Steinbach, personal communication):

• If the obstacle is greater than 61 m (200 ft.) in depth: 

no requirement for aids to navigation

• If the obstacle is from 61 m to 26 m (200 ft. to 85 

ft.) in depth: unlighted buoys are required

• If the obstacle is 26 m to 11 m (85 ft. to 35 ft.) in 

depth: lighted buoys are required

• If the obstacle is from 11 m (35 ft.) to protruding 

through the surface: lights or lighted buoys and foghorns are required.

In the rigs-to-reefs programs in the Gulf of Mexico, 

the states are responsible for aids to navigation on reefed 

platforms. The costs of these aids are paid for from the 

funds created by the industry’s donations. As a cost savings measure, these states generally have selected greater 

water clearances. The requirements for California waters 

may be different from those in the Gulf of Mexico. The local Coast Guard District will determine these requirements 

based on vessel traffic and other local conditions.

The question of liability for a reefed platform off 

California 

Liability, who retains responsibility for a reefed platform, is a major issue in the decommissioning process. 

MMS policy states the “The MMS supports and encourages the reuse of obsolete offshore petroleum structures 

as artificial reefs in U. S. Waters.” Current MMS regulations 

provide that a platform operator may be released from 

removal obligations in the federal lease instrument if a 

state agency responsible for managing fisheries resources 

will accept liability (30 C.F.R. § 250.1730). However, in 

situations where reefs are not managed by a state agency, 

another organization or agency must assume liability, as 

provided in the National Fishing Enhancement Act of 1984 

(Stone 1985). In such cases, liability could possibly be retained by the oil company, transferred to a private entity, or 

handled in some other manner as long as MMS approval 

is received (G. Steinbach, personal communication).

An extensive body of policy and research outlines 

proper procedures for siting and deploying artificial reefs, 

and this information bears upon liability of such structures. 

The National Artificial Reef Plan (NARP) states “When a reef 

has been properly located, marked on navigation charts if 

necessary, and any required surface markers affixed, there 

should be very little potential for liability” (Stone 1985). 

Regarding accidents, which may occur during recreational 

activities near artificial reefs, the NARP further declares, 

“Diving accidents may occur with use by recreational divers. 

In this respect, an artificial reef is like a public park — there 

are dangers in those parks, guardrails and fences cannot 

be placed everywhere, and everyone who visits the park 

assumes some risk of injury. A warning could be placed on 

nautical charts and posted in local dive shops to warn of 

these dangers. However, each case would probably involve 

determination of comparative negligence” (Stone 1985). 

Parker (1999) notes that no lawsuits have ever been filed 

against the California Department of Fish and Game with 

respect to their artificial reef program.

Regardless of which decommissioning alternative is 

selected, the federal government cannot be held liable. 

Regarding State liability, the NARP notes, “If the permit 

holder is a State government, it may have sovereign immunity from liability. It is unclear whether the National 

Fishing Enhancement Act affects any State‘s claim of 

sovereign immunity.” (Stone 1985)

the well conductors at the same depth below the water 

line (WL) at which the industry had proposed to remove 

the platform jacket.” Retaining platform conductors has 

two consequences. First, it adds additional complexity 

to remaining structure. Second, explosives are usually 

used to remove the conductors and retaining these pipes 

eliminates the need for explosives (Dauterive 2000).

After cleaning, disposition of topsides may be handled in a couple of ways. It can be moved to a new platform and reinstalled, or it can be taken onshore, where 

the steel and other valuable components are recycled 

and other material sent to landfills. Certain parts of the 

topsides, such as the cleaned deck, have occasionally be 

used in forming artificial reefs.

Alternative 3: TOPPLING

As in partial removal, the wells are abandoned and 

the topsides are removed. The shell mounds may be either 

removed or left in place. The primary difference between 

partial removal and toppling is that, in toppling, explosives are used to sever the jacket from the seabed and then 

a derrick barge or pull barge drags the jacket over and 

it is allowed to settle to the seafloor (Twachtman 1997). 

Navigational aids, if necessary, are then put in place.

Alternative 4: NO REMOVAL (LEAVE-IN-PLACE)

A platform and its surrounding shell mound could 

be left in its original location at the time of decommissioning. The topside would be stripped and cleaned and 

navigational aids installed. 

In the Gulf of Mexico this scenario has been discussed on a number of occasions, although it has not 

been attempted. For instance, a platform in the Flower 

Garden Banks National Marine Sanctuary was studied 

as a possible research laboratory. However, the cost of 

maintaining cathodic protection and navigational aids 

(together running to $300,000 per year) proved too high 

(L. Dauterive, personal communication). Other creative 

suggestions offered by stakeholders for decommissioned, 

left-in-place platforms include wind and aquaculture 

farms, meteorological stations, hospitals, hotels, gambling casinos, and penal institutions.

Agencies Responsible for the 

Decommissioning Process 

By law, various coastal states and the federal government share the administration of submerged lands, 

subsoils and seabeds off the United States. Thus, depending on where platforms are positioned, responsibility for 

mineral extraction, including oil and gas development, is 

either under state or federal jurisdiction. Similarly, decisions regarding the decommissioning of platforms fall 

under either state or federal control, although the final 

decisions are based on consultation and mutual agreements among a number of agencies.

Responsibility for the fate of platforms in federal 

waters rests with the MMS (33 U.S.C. § 1331 et seq.) 

Federal agencies that are consulted in the decommissioning process include the Environmental Protection 

Agency (33 U.S.C. §§ 1311(a), 1342), Army Corps of 

Engineers (33 U.S.C. §§ 403,1344), National Oceanic 

and Atmospheric Administration (NOAA) Fisheries 

(16 U.S.C. § 1801 et seq.), and Coast Guard (14 U.S.C. 

§ 85: 43 U.S.C. § 1333(d)). State agencies, such as the 

California Department of Fish and Game do not have 

jurisdiction in federal waters but may comment in the 

decision making process. Under the federal Coastal 

Zone Management Act (16 U.S.C. § 1451 et seq.), MMS 

decisions on platform decommissioning that will affect 

coastal resources are also reviewed by the appropriate 

state agency for consistency with the state’s coastal zone 

management program. In California, the California 

Coastal Commission conducts review for consistency 

with the state program. In turn, state agency consistency 

decisions can be appealed to the U. S. Department of 

Commerce (16 U.S.C. § 1456(c)(3)(A), (c)(3)(B)(iii); 

15 C.F.R. Part 930, subpart H).

Decisions regarding the decommissioning of platforms in California state waters are the province of the 

State Lands Commission (CAL. PUB. RES. CODE § 6216), 

along with such agencies as the California Coastal Commission (CAL. PUB. RES. CODE § 30330), Department of 

Fish and Game (CAL. FISH & GAME CODE § 1602), local Air 

Pollution Control Districts (CAL. HEALTH & SAFETY CODE

40000), U. S. Army Corps of Engineers (33 U.S.C. §§ 403, 

1344), and the U. S. Coast Guard (14 U.S.C. § 85).
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DECOMMISSIONING OPTIONS AND ISSUES

4-7

DECOMMISSIONING OPTIONS AND ISSUES

National Artificial Reef Plan 

Decommissioning options other than complete 

removal must be consistent with the National Artificial 

Reef Plan (33 U.S.C. § 2104(a)(4)). The National Fishing Enhancement Act of 1984 directed the development 

of a long-term National Artificial Reef Plan (NARP) to 

provide guidance and criteria on planning, construction, 

and evaluating artificial reef use, as well as introducing 

liability and mitigation issues (33 U.S.C. § 2103). Goals of 

the NARP seek to enhance fishing and fishery resources 

and minimize user conflicts and environmental risks 

without creating unreasonable obstruction to navigation 

(33 U.S.C. § 2102). In 1998, the NARP was supplemented 

by the Coastal Artificial Reef Planning Guide, which incorporates new language from relevant federal and state 

agencies, fishing interests, and the general public. 

California Department of Fish and Game 

Rigs-to-Reef Guidelines 

“These guidelines stipulate that the project 

must benefit living marine resources, habitat, and 

user groups; that disposal or use of contaminated 

materials is not permitted; that wherever possible the 

subsurface structure of the platform should remain 

in place; that where possible subsurface structure 

that must be removed could be relocated to the base 

of the rig or other appropriate sites; and that the 

remaining structure be augmented by rocks or other 

materials to assure that the site functions as a diverse 

and productive reef habitat. To replace the biotic productivity from that part of the platform removed for 

navigational purposes, rock or concrete reefs should 

be placed in nearshore locations. A rigs-to-reef project 

sponsor must provide sufficient funds to the Department to evaluate the benefits to biotic productivity, 

user groups, and the overall management of fishery 

resources.” (Holbrook et al. 2000)

Social Values in Platform Decommissioning

Defining the social and ecological goals of decommissioned platforms as artificial reefs will be critical 

in evaluating the efficacy of any potential rigs-to-reef 

program and the current and future performance of 

any artificial reef. Therefore, it is likely that various 

stakeholder groups will vie in defining the goals (and 

therefore the usefulness) of decommissioned platforms 

as artificial reefs. In this report, we sort the multitude of 

stakeholder viewpoints regarding a rigs-to-reef program 

into three groups, each of which is primarily defined 

by one concern: community membership, resource accessibility and environmental (marine life) issues. Of 

course, an individual may be influenced by more than 

one social value, and others may use arguments from 

multiple categories to promote a desired decommissioning outcome. 

The first group consists of stakeholders who are 

concerned about community membership, and either 

oppose or support local presence of the oil industry. 

Those that wish to promote a community without the 

oil industry often view reefing alternatives as bundled 

together with all oil industry activities (e.g., continued 

exploration and production), the whole of which should 

be locally opposed (although they may not be opposed 

to oil industry activities in the Gulf of Mexico). For example, Camozzi (1998a) states that complete removal 

should be the preferred alternative in decommissioning 

because, after decades of fighting oil development on the 

California Coast, it acts as a “catharsis” for the local community. Camozzi (1998b) reiterates this point by stating 

that, in regard to mussel mound removal, “Sending a 

message to oil companies that they must clean up our 

coast when they are done extracting their profits is the 

most vital issue in this case.” Individuals who wish to 

encourage or maintain the presence of the oil industry in 

the local community, presumably for economic reasons, 

favor some sort of reefing option because reefing is less 

expensive than complete removal (Pulsipher et al. 2000). 

Further information regarding local community views 

on the oil industry in California can be found in Lima 

(1994) and Smith and Garcia (1995). 

The second group of stakeholders is primarily 

concerned with resource accessibility. A heterogeneous 

group, these citizens will either favor or oppose decommissioning alternatives depending on how these 

alternatives aid or inhibit their ability to access a particular resource. For example, commercial trawlers in 

the Southern California Bight favor complete removal 

because fishing gear may snag on platform structure or 

shell mounds (Southern California Trawlers Association 

1998; McCorkle 1999). Other commercial fishers benefit 

from oil industry activities. Shrimp trawlers in the Gulf 

of Mexico drag within 0.4 km (0.25 mi) of platform 

structures, reporting that these fishing grounds tend 

to be more productive (Wilson et al. 1987). The rocky 

habitat associated with Rincon Oil Island in California 

provides excellent lobster fishing grounds and trap fishers would oppose seeing this habitat removed (Miller 

1999). Recreational fishers often dominate the debate 

surrounding platform decommissioning, and they have 

driven the formation of artificial reef policy at both 

state and federal levels (Stone 1985; Wilson et al. 1987). 

Many recreational fishers favor a reefing alternative in 

decommissioning because catch per unit effort is often 

high at offshore platforms for targeted fish species such 

as kelp bass (Love and Westphal 1990; McCrea 1998). In 

the Gulf of Mexico, Reggio (1987) estimates that 70% of 

fishing excursions target oil platform habitats. Citizens 

participating in non-consumptive activities also possess a variety of viewpoints regarding decommissioning 

alternatives. Many scuba divers find that underwater 

portions of oil platforms provide outstanding diving 

and underwater photographic opportunities, and favor 

decommissioning alternatives that preserve such opportunities, (Vallette 1999). Other members of the public 

may view the topside structure of platforms as denying 

them access to unobstructed, scenic ocean views, and 

consequently they oppose the leave-in-place decommissioning option (Wiseman 1999).

The third stakeholder group makes decisions regarding decommissioning based on their perception of how 

certain marine populations or environmental ideals fare 

under the various decommissioning alternatives. It is this 

last group that is most likely to use ecological information 

in making decisions regarding platform decommissioning. A decommissioning option that involves reefing may 

be supported if a substantial net benefit to the marine 

environment can be demonstrated (Chabot 1999). 

Others support complete removal because this option 

is the only one which promotes a wilderness ideal, that 

is, a marine environment which fails to retain a visible 

mark of human activities. If there is a lack of scientific 

evidence regarding ecological consequences, or if they 

are unaware of such consequences, these stakeholders may use another social value, such as community 

membership, in choosing a preferred decommissioning 

alternative (Chabot 1999). 

Economic incentives interact and overlap with social 

values. In past rigs-to-reefs activities, industry and state 

entities have equally shared the cost-savings resulting 

from partial removal or toppling alternatives. Partial removal of deep water platforms will generate estimated 

savings of one to two orders of magnitude greater than 

the amount saved in decommissioning smaller platforms. 

The cost of maintaining navigational equipment (if any is 

needed) at these reefed platforms will not increase in the 

same proportion as the increase in cost-savings, and may 

actually decrease. These additional financial resources 

may be used to develop or enhance projects of interest to 

stakeholders, and may be a sufficient incentive to alter the 

preferred decommissioning option for some groups. 

The Interaction of Science, Scale, and Social Values

State and federal regulatory agencies involved in 

the decommissioning process are required to protect 

the public interest when managing natural resources. 

In the face of strongly conflicting viewpoints among 

stakeholder groups, resource managers may try to 

convert a controversial issue into a technical one. For 

instance, they may give preference to the protection of 

marine life resources, thereby avoiding the appearance of 

favoring one group’s economic concerns over another’s. 

Additionally, legislation such as the Endangered Species 

Act and the Marine Mammal Protection Act, among 

others, often give environmental concerns priority over 

social and economic concerns. In combination, these 

issues give ecological information a prominent role in 

the decommissioning process.

Impacts to the environment may be measured at 

short or long time scales, or within a local or regional 

context. As time and space scales increase, so does scientific uncertainty about predicting consequences of 

various management alternatives (due to an increasing 

number of unknown variables and propagation of error 

associated with imprecise assumptions or model parameters). When there is greater scientific uncertainty, social 

values and political or economic factors often become 

more important in the decision-making process. This 

phenomenon may result in stakeholders advocating that 

ecological performance of reefed platforms be evaluated 

at scales which enhance the possibility of their preferred 

decommissioning alternative, even if ecological data are 

irrelevant to their concerns. 

For example, proponents of regional ecological 

assessment at long time intervals may be individuals who oppose the local presence of the oil industry. 

Since regional assessment is difficult and expensive to 

accomplish, social values (e.g., antagonistic views of oil 

industry) will increase in importance. Significantly, these 

same individuals have not stipulated that other artificial 

reefs which are similar to reefed platforms, such as steel 

hulled ships, undergo the same rigorous ecological assessment. Further, the assured instantaneous and lethal 

effects of explosives are not considered in arguments 

about marine life effects. 

Proponents of small scale ecological assessment tend 

to be recreational anglers, who often state their support 

for rigs-to-reef programs in terms of benefits to the 
4-8

DECOMMISSIONING OPTIONS AND ISSUES

4-9

DECOMMISSIONING OPTIONS AND ISSUES

environment. They maintain that the local presence of 

abundant marine life at a platform is sufficient evidence 

of satisfactory ecological performance. But this support 

for a rigs-to-reef alternative often evaporates if artificial 

reefs are designated no-take areas. 

Ecological information greatly aids the decision-making process if explicit management goals are 

specified. The rebuilding of depleted fish stocks might 

be one goal, the preservation and expansion of marine 

wilderness might be another. Determination and ranking of ecological goals reflects cultural values. Thus, 

controversies surrounding platform decommissioning 

cannot easily be translated into technical issues by giving 

priority to ecological goals because we lack agreement 

on the space and time scales in which ecological impacts should be measured. Therefore, the scale at which 

ecological impacts are measured (local or regional) and 

considered (short or long term) becomes paramount in 

the decommissioning process. To date, such specific space 

and time scales have not been designated by any state or 

federal government agency.

Decommissioning Activities in the Gulf of Mexico

To date, almost all platform decommissioning and 

reefing in the world has occurred in the Gulf of Mexico. 

Because large-scale offshore drilling first took place in the 

Gulf of Mexico, it was in this region that the issue of what 

to do with unwanted platforms first arose. Below, we give 

a brief summary of the history of decommissioning in the 

Gulf of Mexico; additional details are found in Lukens 

(1997), Kasprzak (1998), and Dauterive (2000).

Kerr-McGee erected the first offshore oil and gas 

platform in the Gulf of Mexico off Louisiana in 1947. 

Despite its primitive structure and placement in waters 

only 6 m (18 ft.) deep, oil was struck 22 days after drilling began, presaging a veritable tidal wave of offshore 

drilling. In 2001, there were over 4,000 platforms in the

Gulf of Mexico, the vast majority occurring off Louisiana, followed by Texas, Mississippi and Alabama (Lukens 

1997; Moritis 1997; Kasprzak 1998, 1999; Dauterive 

2000). Platforms provide a considerable amount of the 

hard substrate in the north-central Gulf of Mexico, and 

surveys indicate that 20%–50% more fish live around 

platforms than on surrounding soft seafloors (Gallaway 

and Lewbel 1982; Driesen 1985). Because recreational 

and commercial fishers target fish residing near these 

structures, they are of considerable economic value 

(Dimitroff 1982; Reggio 1987; Kasprzak 1998). 

By the late 1970s, it was apparent that the economic 

life span of many of these structures was nearing an end. 

During that decade, about 150 platforms were removed 

to shore and scrapped. The first reefing of an oil and gas 

structure occurred in 1979 when a subsea production 

system was towed from Louisiana to an artificial reef site 

off the Panhandle of Florida. In 1982, an obsolete platform jacket was moved from Louisiana to a Dade County, 

Florida site and over the next few years several additional 

structures were moved to various artificial reef sites. 

Responding to this new activity, Congress passed the 

National Fishing Enhancement Act (NFEA) in 1984 (33 

U.S.C. § 2101 et seq.). The NFEA mandated the creation 

of a “long-term plan for siting, constructing, permitting, installing, monitoring, managing, and maintaining 

artificial reefs within and seaward of state jurisdictions” 

(Kasprzak 1998). This document, later called the National 

Artificial Reef Plan, was published in 1985.In response to 

NFEA, several Gulf of Mexico states have now passed laws 

to take advantage of platform decommissioning to help 

preserve complex habitat in the northern Gulf of Mexico, 

for example, the Louisiana Fishing Enhancement Act of 

1986 (LA. REV. STAT. § 56:639.1 et seq.) [Act 100] and the 

Texas Artificial Reef Act of 1989 (TEX. PARKS & WILDLIFE

CODE § 89.001 et seq.). As an example, Act 100 created a 

process by which ownership of and liability for uneconomical platforms could be transferred from operators to 

the state of Louisiana. As noted by Kasprzak (1998), “Act 

100 established the State of Louisiana as the permittee for 

artificial reefs developed under the program’s jurisdiction 

and appointed the Department of Wildlife and Fisheries 

as agent for the state. The state assumes responsibility 

for the reefs upon placement within the established reef 

permit area...Act 100 does not authorize state general 

funds for the artificial reef program but does establish the 

Louisiana Artificial Reef Trust Fund. Oil and gas companies that donate structures to the program are asked to 

contribute half of the disposal savings realized through 

program participation to the trust fund.” A similar program exists in Texas (Texas Parks and Recreation 1999).

A significant amount of money has been collected 

in rigs-to-reef programs in both Louisiana and Texas. 

As of 2001, there was about $15 million in the Louisiana 

fund and at least $4 million in Texas. Contrary to what 

has been reported (McGinnis et al. 2001), major artificial 

reef programs of several states, including Louisiana and 

Texas, receive neither state nor federal funding, they are 

fully underwritten by the interest paid on their respective 

rigs-to-reef accounts (J. Culbertson, personal communication; R. Kasprzak, personal communication). The 

Louisiana Department of Wildlife and Fisheries and 

Texas Parks and Wildlife Department describe their rigsto-reefs programs at http://www.wlf.state.la.us (under 

“Marine Fisheries”) and http://www.tpwd.state.tx.us/

fish/reef/artreef.htm, respectively. 

Since 1942, over 188 Gulf of Mexico platforms have 

been reefed, primarily off Louisiana and Texas. This represents about 8.4% of all decommissioned platforms (L. 

Dauterive, personal communication). The reasons for 

this early low reefing rate were economic. Most of the 

platforms thus far decommissioned were in shallow water, and it was more cost effective to haul them onshore 

for salvage or reuse rather then tow them to reefing sites. 

In the future, it is likely that a higher proportion of platforms will be reefed as more offshore structures become 

obsolete. Of the platforms that have been reefed, about 

60% have been removed from a site and towed to a new 

location. Contrary to what was stated by Krop (1998), 

some decommissioned platform structures have been left 

in place. Thus far, 30% have been toppled in place and the 

remainder have been partially removed and left standing 

(Dauterive 2000). As larger platforms in deeper waters 

are decommissioned, L. Dauterive (personal communication) has noted a trend towards partial removal, rather 

than towing or toppling. In all but a few instances, only 

the platform jacket has been used as reef material.

The Future: Ecological Consequences of 

Offshore Platform Decommissioning in 

California 

Complete Removal (Total Removal) of Platform

The immediate impact of removing and hauling an 

entire platform to shore is that all attached animals die. 

If some of the platform structure is hauled to a reef area 

and replaced in the water, some of these animals may 

survive, depending on water depth and the length of 

time the structure is exposed to the air.

Using explosives to separate the jacket from the 

seafloor kills large numbers of fishes, although limited 

research makes it difficult to predict how many deaths 

will occur. Marine mammals and sea turtles may also be 

indirectly killed by damage to the auditory system. In a 

study in the Gulf of Mexico (Bull and Kendall 1994), 

explosives were placed 5 m (15 ft.) below the seafloor to 

sever the well conductors, platform anchor pilings and 

support legs, of a platform in about 30 m (100 ft.) of 

water. All of the fishes on or near the bottom and most 

of the adult fishes around the entire platform suffered 

lethal concussion. 

Some shallow-water platforms can be removed 

without explosives. However, “The oil and gas industry 

has attempted to find alternatives to the use of explosives, such as cryogenic cutting, hydraulic abrasive 

cutting, mechanical cutting, and torch cutting. Most of 

these techniques either have proven to be ineffective or 

are successful only in limited situations. At present, the 

industry maintains that the use of explosives is by far the 

safest, most reliable, and most cost-effective method of 

platform removal” (Kasprzak 1998). A recent assessment 

of techniques for removing platforms (NRC 1996) found 

that it is unlikely that any techniques or devices now 

known will significantly reduce fish kills during removal 

operations that use explosives.

Shell Mounds at the Base of Platform 

The jackets and conductors of all platforms off 

southern and central California are heavily encrusted 

with invertebrates, including mussels, barnacles, seastars, 

rock scallops, rock oysters and jingle shells, sea anemones, caprellid amphipods, rock crabs, limpets, gooseneck 

barnacles, and sessile tunicates. An extremely thick layer 

of mussels extends from the intertidal zone to depths of 

at least 30 m (100 ft.) (and deeper on some platforms). 

The seafloor surrounding the platforms is covered with 

mussel shells. This “shell mound” or “mussel mound” is 

created when mussels, and other invertebrates, are dislodged during platform cleaning or heavy swells. Our 

observations show that, depending on bottom depth, 

a number of species of invertebrates, including many 

species of seastars, brittle stars, and rock crabs, as well 

as king crabs, opisthobranchs, shrimps, octopi, and sea 

anemones are abundant on the shell mounds. Substantial 

number of fishes, primarily the juvenile stages of various 

rockfishes, adult stages of dwarf rockfish species, as well 

as lingcod, poachers, painted greenling, and other benthic 

species also inhabit shell mounds. 

MILTON LOVE

Juvenile cowcod on pipeline.
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DECOMMISSIONING OPTIONS AND ISSUES

4-11

DECOMMISSIONING OPTIONS AND ISSUES

Around four platforms in shallow water locations 

(+/- about 33 m, 109 ft., water depth), the shell mounds 

were found to be many meters thick, and were found to 

cover accumulations of drilling muds and cuttings. Investigations of the shell mounds around deep-water platforms have not been completed. Nevertheless, because 

of the potential for environmental harm, this issue must 

be addressed for all platforms regardless of the decommissioning option pursued. The level of contamination, 

while localized, has been shown to vary from platform to 

platform. Therefore, any remedial actions taken during 

the decommissioning process will likely be determined 

on a case-by-case basis. Although the regulatory requirements are still evolving, the alternatives being discussed 

include leaving the shell mounds undisturbed, smoothing and shaping them to allow for trawling, capping 

the shell mounds with an impervious material, adding 

material to the mounds for enhancement, or completely 

removing the shell mounds. 

The removal of shell mounds may have a number 

of consequences to marine life by (1) removing habitat 

and (2) the potential for releasing toxins into the water 

column during the removal process. The biological consequences of either removing, altering, or leaving the shell 

mounds in-place must be given appropriate attention in 

the decommissioning process. 

Partial Removal of Platform

Since partial removal reduces or eliminates shallow 

water habitat from the platform structure, this alternative would likely result in lower species composition and 

diversity than at the start of decommissioning process. 

Response of biotic communities will depend upon how 

much of the upper portion is removed. Depending on the 

platform, fewer nearshore reef fishes, such as surfperches, 

basses, and damselfishes may occur. Invertebrates that 

only reside or recruit to shallow water habitat would 

also be absent. Since the majority of mussels are located 

at shallow depths, shell mound replenishment will be 

reduced or absent, and affect the persistence of that 

community.

Since partial removal does not require the use of 

explosives, there is relatively little marine mammal, sea 

turtle, fish and invertebrate mortality compared to complete removal. Vertebrate and invertebrate assemblages 

associated with the remaining platform structure are 

assumed to be minimally affected. 

A number of misunderstandings surround predictions regarding the potential ecological consequences of 

partial removal. 

(1) Some stakeholders and policy analysts have erroneously assumed that Coast Guard regulations require 

a minimum depth below the ocean surface to which a 

reefed platform must be reduced. However, as noted 

earlier, the decision on how much of the jacket and conductors is left in place is based on both a Coast Guard 

assessment and the willingness of the liability holder to 

pay for the requisite navigational aids. As mussels become 

rare below 30 m (100 ft.) on most platforms, the mistaken assumption that all topped platforms must be cut 

to 24–30 m (80–100 ft.) below the surface has led some 

to conclude that partial removal will inevitably lead to 

a severe reduction in the amount of mussels that fall to 

the bottom and, thus, to a change in or end to the shell 

mound community. This is not necessarily the case. 

(2) Some reports suggest that partial removal will 

lead to a large decrease in juvenile rockfish densities; 

our research does not support this supposition. On the 

offshore platforms in the Santa Barbara Channel region, 

the juveniles of most rockfish species (particularly blue, 

bocaccio, halfbanded, olive, pygmy, squarespot, starry, 

widow, and yellowtail) are uncommon in waters shallower than 26 m (85 ft.). Partial removal could reduce 

fish densities if pelagic juvenile stages of these rockfishes 

first encounter a platform in shallow surface waters, then 

swim downwards below the 26 m range, causing pelagic 

juveniles to “miss” a platform. However, young-of-theyear rockfishes of many of these species recruit from 

the plankton in large numbers both to natural outcrops 

in nearshore waters and to those coming out of deeper 

waters that have crests in about 30 m (100 ft.) of water. 

This indicates that emergent structure is not necessary 

for these juveniles to locate suitable habitat.

On the other hand, the pelagic stage of a few rockfish 

species, particularly copper, gopher, black-and-yellow, 

and kelp may prefer to recruit shallower portions of 

the platform than other rockfish species (Holbrook et 

al. 2000; this report). These species recruit to nearshore 

rocky outcrops and kelp beds and do not appear to settle 

in deeper waters (Larson 2002a,b). For these species, 

partial removal of a platform would probably decrease 

juvenile recruitment, depending on the uppermost depth 

of the remaining structure.

(3) Errors regarding factors affecting juvenile fish 

mortality have also lead to confusion. McGinnis et al. 

(2001), in describing the history of artificial reef research 

in California, states that “Research has shown that high 

relief, open structures serve best to attract fish, and better enable fishery exploitation, while low relief, complex 

structured reefs provide better nurseries and afford more 

diverse assemblages of fish and other organisms”. McGinnis et al. (2001) also cite an anonymous California 

Department of Fish and Game biologist who notes that 

“a drawback to rigs as reefs is that they are high relief, 

which works against survival of young-of-the-year fish, 

suggesting they may not be a source of production but 

rather simply an attraction site.” 

We know of no research that can support the above 

claims, and the authors do not cite any specific studies. 

Predators are the main source of juvenile fish mortality 

in marine systems; death due to starvation or exposure 

is rare. Thus, variation in habitat structure would modify 

juvenile fish survivorship by modifying the success rate of 

predators. Presently, no studies have assessed comparative performance in survivorship rates between platforms 

and natural habitats. Alternatively, we may begin to infer 

potential predator vulnerability between habitats by examining the ratio of juvenile fishes to piscivorous fishes. 

In the shallow portion of Platform Irene, the ratio of 

juvenile rockfishes to piscivorous fish is about 25:1 and 

at nearby Tarantula Reef it is 3:1 (Appendix 2; Schroeder, 

unpublished data). Conversely, in the east Santa Barbara 

Channel, at Platform Gina the ratio is 1:5, and at Portuguese Rock, Anacapa Island it is 1:1.4. 

Toppling of Platform 

Toppling would produce reefs with somewhat different fish assemblages than what has been observed around 

intact platforms. Consequences of removal of shallow 

water habitat would be similar to that of partial removal. 

In California, because most platforms reside in fairly 

deep water, toppled platforms would also harbor fewer 

young-of-the-year rockfishes, just as the reefs adjacent 

to Platform Hidalgo harbor fewer of these animals. Depending on the characteristics of the platform, a toppled 

structure, with twisted and deformed pilings and beams, 

might have more complexity than an upright one. This 

might increase the number of such crevice dwelling fishes 

as pygmy rockfishes.

No Removal (Leave-in-Place) of Platform

The no-removal option would allow the platform 

and shell mound to continue to function as they had 

when the structure was occupied. Decommissioning 

activities would result in small mortality impacts to 

resident marine populations.

What is the Life Span of a Reefed Platform?

How long can a decommissioned steel platform 

survive in the marine environment before rusting 

away? Operating steel platforms are protected by 

sacrificial anodes, often made of aluminum or zinc, 

which preferentially corrode before steel, thus preserving the jackets’ integrity. This cathodic protection lasts 

as long as the anodes are intact, usually for a number 

of decades. It is assumed that, once a platform is 

reefed, there will be no additional replacement of 

the sacrificial anodes, although the issue has yet to 

be addressed for platforms off California. While corrosion rates vary in seawater, depending on water 

temperature, biofouling and other factors, it is estimated that the life span of a cathodically unprotected 

platform will range from a minimum of 100 to more 

than 300 years (Quigle and Thorton 1989; Mishael 

1997; Voskanian and Byrd 1998).

Pipelines Associated with Platforms

Pipelines run from all platforms either to shore 

or to other platforms that collect the oil or gas and 

then ship it to shore. McGinnis et al. (2001), note that 

“Both Federal and California regulations allow decommissioned OCS pipelines to be abandoned in place so 

long as they do not constitute a hazard to navigation, 

commercial fishing or unduly interfere with other uses 

of the OCS.” (See also 30 C.F.R. § 250.1750; CA. PUB. 

RES. CODE § 6873.) In the Gulf of Mexico, few pipelines have been completely removed in the course of 

decommissioning (Breaux et al. 1997).

In 2001, using the research submersible Delta, 

we conducted pilot surveys of a pipeline between 

Platforms Gail and Grace. We found this pipe to be 

heavily encrusted with such invertebrates as anemones, crinoids, basket stars, and seastars. We also noted 

relatively large numbers of fishes, particularly juvenile 

or dwarf fishes, including cowcod, flag, blackgill, 

striped, and vermilion rockfishes, along with poachers and flatfishes. Both fish and invertebrate densities 

were much higher than found on the surrounding 

mud bottom.
4-12

DECOMMISSIONING OPTIONS AND ISSUES

5-1

Resource Management Issues Associated 

with Decommissioning

Habitat Enhancement of Reefed Platform Structure 

The California Department of Fish and Game has 

issued guidelines for rigs-to-reef projects that call for 

enhancing the remaining structure using quarry rocks 

or other material (Parker 1998). Adding such material 

would increase the number of crevices and hiding places 

suitable for smaller sized fish. Thus, species which are 

rare or absent from observed platform fish assemblages, 

such as pygmy rockfish, may then occur. The ecological 

community response may depend on the type of habitat 

enhancement and has not been examined.

Marine Protected Areas

To a certain extent, the platforms in the Santa Barbara Channel and Santa Maria Basin currently act as de 

facto marine protected areas (Schroeder and Love 2002). 

Fishing pressure around many of these platforms is relatively low because (1) some platforms are relatively far 

from harbors and thus from fishing vessels, (2) four platforms (Irene, Hidalgo, Harvest, and Hermosa) are located 

near Point Conception in waters that are extremely rough 

for much of the year, and (3) it is difficult to fish close to 

operating platforms because tying up to these structures 

is discouraged by platform operators. 

Clearly, many reefed platforms would be a target for 

recreational anglers or commercial fishermen because 

platforms often host sizable local populations of soughtafter fish species. Off Florida, Shinn and Wicklund (1989) 

suggest that patterns of large fish at Tenneco platforms 

may be in part determined by fishing activities. Thus, in 

California, it has been proposed that reefed structures 

be designated as no-take areas (California senate bill introduced by D. Alpert). In addition, it may be possible 

to modify the architecture of reefed platforms to make 

them difficult to fish. For instance, because most of the 

target species are found inside the bottom of platform 

any structure above the bottom would prevent gear 

from reaching the seafloor, thus inhibiting the capture 

of many fishes.

Decommissioning Alternatives in Relation to National 

Marine Fishery Service’s Fishery Rebuilding Plans

The use of explosives to remove or topple a platform 

may compromise fishery-rebuilding programs. Cowcod 

provide one example. This species has been declared 

overfished by NOAA Fisheries (formerly known as the 

National Marine Fisheries Service) and is the subject of 

a federal rebuilding plan. The Pacific Fisheries Management Council has approved a cowcod rebuilding plan 

that limits fishery impacts to 1% per year (about 2.4 

metric tons for 2001), as part of a 95-year rebuilding 

period, and the use of spatial closures south of Point 

Conception to reduce bycatch mortality. As noted earlier,

our observations around Platform Gail indicate it has 

the highest density of adult cowcod and bocaccio of any 

natural or artificial structure surveyed. We can make an 

estimate of the number of cowcod at the bottom of Gail 

by multiplying the density of cowcod observed by the 

area of the platform’s footprint (the area underneath the 

platform). For instance, in the last two years of the survey, 

1999 and 2000, observed cowcod densities were 0.015 

and 0.0183 fish per m2, respectively. As Gail’s footprint 

is 5,327 m2 (Holbrook et al. 2000), extrapolation for 

1999 and 2000 gives estimates of 79 and 97 individuals 

respectively. This conservative estimate does not include 

juveniles we have observed living on the shell mound or 

on the adjacent pipeline. The current rebuilding plan calls 

for both a quota on commercial and recreational fisheries combined of 2.4 metric tons, equal to about 600 fish 

(T. Barnes, personal communication). Assuming that 

Platform Gail has 75 or more cowcod living under it, 

and if, as seems likely from all known research, explosives 

used to remove or topple a platform will kill all of them, 

that loss may be sufficiently large to complicate the rebuilding plan (T. Barnes, personal communication). 

CHAPTER 5 

RESEARCH AND MONITORING 

RECOMMENDATIONS

When Governor Davis vetoed SB 1, a bill that would have 

allotted some of the savings derived from reefing platforms to California, he wrote, “ There is no conclusive evidence that converted platforms enhance marine species or 

produce net benefits to the environment...it is premature 

to establish this program until the environmental benefits 

of such conversions are widely accepted by the scientific 

and environmental communities.” And, with respect to 

assessing the effect of different decommissioning options 

on marine populations, Holbrook et al. (2000) state that 

the key marine ecological question is, “What is the effect 

of each decommissioning alternative on regional stocks of 

reef-associated species in general, or of particular targeted 

species?” Clearly, in the decommissioning process, there 

is a need for additional information.

Below we list examples of research that would be 

useful in addressing these issues. Many of these examples 

have been suggested by various resource managers. The 

first two tasks are necessary to resolve issues regarding 

attraction or production of platform and natural habitats 

as well as helping to define essential fish habitat. In addition to aiding in the platform decommissioning process, 

these three tasks will also aid in future coastal zoning 

and mapping that would occur in any future boundary 

expansion of the Channel Islands Marine Sanctuary.

Compare ecological performance between 

oil platforms and natural outcrops and 

determine if any oil platforms serve as 

Essential Fish Habitat for focal species.

What fishes live around platforms and nearby 

natural reefs?

In order to assess the relative importance of a platform to its region, it is essential to conduct basic surveys 

not only around the platform, but also at nearby reefs. 

A majority of platforms have not been well surveyed or 

have not been surveyed at all. Both scuba and submersible surveys must be conducted.

How does fish production around platforms compare to that at natural outcrops? 

Fish production can be assessed and compared 

between habitats by examining a number of ecological 

yardsticks. These include (1) fish growth rates, (2) mortality rates, and (3) reproductive output. As an example, 

we conducted a pilot study comparing the growth rates 

of young-of-the-year blue rockfish at Platform Gilda 

and Naples Reef. More research needs to be conducted 

in all of these areas. For instance, mortality rates can 

be estimated by sequential surveys of the densities of 

young fishes at a specific platform or natural outcrop. 

Reproductive output (larval production in the case of 

rockfishes) can be quantified by first estimating the size 

frequency and density of a species at a platform or natural 

outcrop. Then, using size-fecundity relationships from 

the literature, the potential annual larval production for 

that species can be calculated. 

How does trophic structure around 

platforms compare to that at natural 

outcrops? 

How do platforms and natural outcrops compare 

in terms of habitat value? 

A relatively new measure called Habitat Value (HV) 

allows comparisons between habitats, incorporating fish 

density, fish length, and fish regularity of occurrence. 

In Stephens et al. (1999), we presented a preliminary 

analysis of nine platforms and found that platform HVs 

tended to be much higher than those for open coastal 

soft substrate, higher than low relief deep rock outcrop 

and in the same range as wetlands and kelp/rock natural 

outcrops. An analysis of all of the platforms and as many 

outcrops as possible should be conducted. 

Can we identify areas that are Essential Fish Habitat? 

All of the above studies contribute to answering 

this question. 

Spotted ratfish on shell mound at Platform Gail.

LOVELAB, UC SANTA BARBARA
5-2

RESEARCH AND MONITORING RECOMMENDATIONS

5-3

ACKNOWLEDGEMENTS AND PERSONAL COMMUNICATIONS

Define the spatial distribution of 

economically important species (all 

life history stages) within the region 

of interest and define connectivity of 

habitats within this region.

What is the relative contribution of platforms in 

supplying hard substrate and fishes to the region? 

This research would put in perspective the relative 

contribution of platforms in supplying hard substrate 

and reef fishes to their environment. 

First, this requires an assessment of the rocky outcrops in the vicinity of each platform; this is derived from 

seafloor mapping. Much of the seafloor in the vicinity of 

platforms remains to be characterized. Once the mapping is complete, visual surveys of the outcrops, using a 

research submersible, will determine the fish assemblages 

and species densities in these habitats. Knowing the areal extent of both natural and platforms habitats and 

the densities of each species in both of these habitats, it 

is then possible to assess the total contribution of each 

platform to the fish populations and hard substrate in 

that region.

How long do fishes reside at platforms? 

It remains unclear how long fishes are resident 

around a platform. For instance, do the large numbers 

of fishes, such as the overfished bocaccio and cowcod, 

remain around the platforms for extended periods? One 

settled on a platform, how long do young-of-the-year 

fishes remain there? A knowledge of the residence time 

of these species would allow for a more accurate determination if platforms form optimal habitat for these species and if they are indeed acting as long-term marine 

reserves. Residence time can be determined through the 

use of both tagging studies and observations of a year 

class through time. 

Acoustic tags are one way to determine fish residency. 

In a pilot study, Dr. Christopher Lowe, at California State 

University, Long Beach, captured and acoustically tagged 

rockfishes at Platform Gail and, after one year has determined that all have remained around the platform. 

Broader studies, covering additional platforms, outcrops, 

and species are needed.

What are the effects of platform retention or 

removal on fish populations within a region? 

As an example, what effect would platform retention 

or removal have on fish recruitment? For instance, would 

the young rockfishes that settle out at a platform survive 

in the absence of that platform? Our surveys demonstrate 

that planktonic juvenile fishes, particularly rockfishes, 

often settle out of the plankton to a platform in substantial numbers. If that platform did not exist, would 

these young fishes have found, and settled upon, natural 

outcrops? In a pilot project, we are using radar-derived 

(CODAR) current data to estimate where the young 

rockfishes that settled at Platform Irene would have 

gone if Irene had not existed. We identify the direction 

and distance of pathways from the platform to natural 

outcrops. A directional histogram of radar-derived trajectories will show the degree to which surface currents 

potentially carry larvae in any given direction from the 

platform site. Knowing how long it would take rockfish 

larvae to reach suitable natural outcrops, and what 

percent of these larvae would likely die before reaching 

these outcrops, will give a sense of the importance of a 

platform as a nursery ground. Similarly, using a synthesis 

of oceanographic information, it is possible to model 

the drift direction of larvae produced by fishes living at 

a platform.

It would be useful to understand the natal origins of 

fishes residing at platforms and natural outcrops. Both 

genetic and otolith microchemistry techniques might aid 

in determining the degree of dispersal of fishes produced 

at platforms and natural outcrops. 

Understand how habitat modification 

of platform environment (e.g., removal 

of upper portion or addition of bottom 

structure) changes associated assemblages 

of marine life at offshore platforms.

All decommissioning options except leave-in-place 

involve modification of the current physical structure of 

offshore platforms. Is it possible to increase fish diversity 

and density by altering the seafloor or the platform itself? 

For instance, it would be useful to add complexity, in 

the form of quarry rock or other structure, to the shell 

mound around a platform, and follow the changes in 

fish assemblages.

Descriptive information such as depth distribution 

and life history information is also useful in determining 

how decommissioning options affect the environment. 

Experimental research, using a BACI design or similar approach, can aid in predicting how the biotic community 

will respond to such structural changes.

ACKNOWLEDGEMENTS

This research was funded by the Biological Resources Division, U. S. Geological Survey (National Offshore Environmental Studies Program 1445-CA-0995-0386) based on an information need identified by the Minerals Management Service’s Pacific OCS Region, as well as by the Minerals Management Service and the California Artificial Reef 

Enhancement Program (CARE). We would like to thank Lyman Thorsteinson for his unflagging support for this 

research. Ann Bull and Lyman Thorsteinson carefully reviewed the first draft and we wish to express our sincerest 

thanks. George Steinbach reviewed our discussion of the platform decommissioning process and options and made 

very constructive comments. 

We greatly appreciate the efforts of Roberta Bloom, UCSB Artworks, who was responsible for the layout and many 

of the graphics. Also, we would like to thank the following companies for granting us permission to survey their platforms: Arguello Associates, Chevron Texaco, Nuevo Energy Company, Pacific Operators Offshore, Torch Operating 

Company, and Venoco Incorporated.

We thank the pilots of the submersible Delta, Chris Ijames and Dave Slater, for their very professional handling of 

the technical aspects of that survey, as well as the crews of the R/V Cavalier, R/V McGaw and R/V Valero. Linda Snook 

managed the deep-water survey data. We thank Craig Syms for his masterful analyses of the deep-water survey data. Frank 

Donohue, skipper of the F/V Gus D, was an essential part of our pelagic fish surveys. Dr. Edward Brothers compared 

daily growth rates of blue rockfish. Dr. Mark Carr provided advice and field assistance early in the research program. 

Dr. Libe Washburn assisted us in planning the biological oceanographic surveys and in subsequently interpreting data 

from those surveys. Many thanks to the scuba divers who helped us collect data, including Arnold Ammann, Scott 

Clark, Becky Frodsham, Lise Goddard, William Golden, Jeff Harding, Eric Hessell, Janine Kido, Laird MacDonald, Scott 

Mau, Melissa Meeker, Michelle Paddack, Chris Thompson, and Jordan Watson. We thank Edwin Beckenbach, Christy 

Herren, Matt Knope, Elan Love, Kurt McClure, Karina Mendiola, Martin Moreti, Dawn Outram, Maria Petueli, Toni 

Ross, David Salazar, Clara Svedlund, Melinda Simmons, Eric Simons and others for all manners of assistance in the field 

and laboratory. Frank Manago and Fred Piltz were always very supportive of our research. We received much useful 

information about platforms and platform decommissioning from Lee Bafalon, Rob Campbell-Taylor, John Deacon, 

Tom Dunoway, Rod Eason, Mike Edwards, Jim Galloway, David Gebauer, Jeff Goddard, Rick Kasprzak, Herb Leidy, 

Jim Lima, Michael Mitchell, Greg Pelka, Karen Robertson-Fall, David Rose, George Steinbach, and Marina Voskanian. 

Glenn Shackell provided the ROV platform inspection tapes. Linda Nelson drew one of the cowcod images for one of 

the figures. The California Department of Fish and Game provided the net for the midwater trawling surveys. Finally, 

we offer apologies to anyone we may have inadvertently forgotten to acknowledge.

PERSONAL COMMUNICATIONS

Tom Barnes, California Department of Fish and Game, La Jolla, California.

Jan Culbertson, Texas Department of Park and Wildlife, Houston, Texas.

Lester Dauterive, Minerals Management Service, New Orleans, Louisiana.

Jennifer Dugan, Marine Science Institute, University of California, Santa Barbara.

Rick Kasprzak, Louisiana Department of Wildlife and Fisheries, Baton Rouge, Louisiana.

Alec MacCall, National Marine Fisheries Service, Santa Cruz, California.

George Steinbach, Ojai, California.

Libe Washburn, Department of Geography, University of California, Santa Barbara.
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Common Name Scientific Name

Greenspotted rockfish Sebastes chlorostictus

Greenstriped rockfish Sebastes elongatus

Halfbanded rockfish Sebastes semicinctus

Halfblind goby Lethops connectens

Halfmoon Medialuna californiensis

Honeycomb rockfish Sebastes umbrosus

Hornshark Heterodontus francisci

Hornyhead turbot Pleuronicthys verticalis

Island kelpfish Alloclinus holderi

Jack mackerel Trachurus symmetricus

Kelp bass Paralabrax clathratus

Kelp goby Lethops connectens

Kelp greenling Hexagrammos decagrammus

Kelp gunnel Ulvicola sanctaerosae

Kelp rockfish Sebastes atrovirens 

Kelp perch Brachyistius frenatus

Lavender sculpin Leiocottus hirundo

Leopard shark Triakis semifasciata

Lingcod Ophiodon elongatus

Longnose skate Raja rhina

Mexican rockfish Sebastes macdonaldi

Mola Mola mola

Mussel blenny Hypsoblennius jenkinsi

Northern anchovy Engraulis mordax

Ocean sunfish Mola mola

Ocean whitefish Caulolatilus princeps

Olive rockfish Sebastes serranoides

Opaleye Girella nigricans

Pacific argentine Argentina sialis

Pacific barracuda Sphyraena argentea

Pacific electric ray Torpedo californica

Pacific hagfish Eptatretus stouti

Pacific hake Merluccius productus

Pacific mackerel Scomber japonicus

Pacific pompano Peprilus simillimus

Pacific sanddab Citharichthys pacificus

Pacific sardine Sardinops sagax

Painted greenling Oxylebius pictus

Phanerodon sp. White seaperch, 

 Phanerodon furcatus or

 sharpnose seaperch, P. atripes

Pile perch Rhacochilus vaca

Pink rockfish Sebastes eos

Pink seaperch Zalembius rosaceus

Pinkrose rockfish Sebastes simulator 

Plainfin midshipman Porichthys notatus 

Pygmy rockfish Sebastes wilsoni

Common Name Scientific Name

Bank rockfish Sebastes rufus

Barred sand bass Paralabrax nebulifer

Barred surfperch Amphistichus argenteus

Bat ray Myliobatis californica

Bearded eelpout Lyconema barbatum

Big skate Raja binoculata

Black-and-yellow rockfish Sebastes chrysomelas

Blackeye goby Rhinogobius nicholsi

Blackgill rockfish Sebastes melanostomus

Black rockfish Sebastes melanops

Blacksmith Chromis punctipinnis

Black perch Embiotoca jacksoni

Bluebanded goby Lythrypnus dalli

Bluebarred prickleback Plectobranchus evides

Blue rockfish Sebastes mystinus

Bluntnose sixgill shark Hexanchus griseus

Bocaccio Sebastes paucispinis

Brown rockfish Sebastes auriculatus

Bull sculpin Enophrys taurina

Cabezon Scorpaenichthys marmoratus

Calico rockfish Sebastes dalli

California halibut Paralichthys californicus

California lizardfish Synodus lucioceps

California scorpionfish Scorpaena guttata 

California sheephead Semicossyphus pulcher

California smoothtongue Leuroglossus stilbius

California tonguefish Symphurus atricauda

Canary rockfish Sebastes pinniger

Chilipepper Sebastes goodei 

C-O turbot Pleuronichthys coenosus 

Copper rockfish Sebastes caurinus

Cowcod Sebastes levis

Darkblotched rockfish Sebastes crameri

Dover sole Microstomus pacificus

Dwarf perch Micrometrus minimus

Embiotoca sp. Black perch, 

 Embiotoca jacksoni or 

striped perch, E. lateralis

Fantail sole Xystreurys liolepis

Flag rockfish Sebastes rubrivinctus

Freckled rockfish Sebastes lentiginosus

Garibaldi Hypsypops rubicunda

Giant kelpfish Heterostichus rostratus

Gopher rockfish Sebastes carnatus

Grass rockfish Sebastes rastrelliger

Gray smoothhound Mustelus californicus

Greenblotched rockfish Sebastes rosenblatti

TABLES

TABLE 1. Common and scientific names of fishes observed in these studies.
T-2

TABLES

T-3

TABLES

Common Name Scientific Name

Rainbow surfperch Hypsurus caryi

Rathbunella sp. Unidentified ronquil

Redbanded rockfish Sebastes babcocki

Rex sole Glyptocephalus zachirus

Rock wrasse Halichoeres semicinctus

Rosy rockfish Sebastes rosaceus

Roughback sculpin Chitonotus pugetensis

Rubberlip seaperch Rhacochilus toxotes

Sarcastic fringehead Neoclinus blanchardi

Sargo Anisotremus davidsoni

Sebastomus sp. Unidentified member of

 rockfish subgenus 

Sebastomus

Senorita Oxyjulis californica

Sharpchin rockfish Sebastes zacentrus

Sharpnose seaperch Phanerodon atripes

Shiner perch Cymatogaster aggregata

Shortbelly rockfish Sebastes jordani

Shortspine combfish Zaniolepis frenata

Shortspine thornyhead Sebastolobus alascanus

Silver surfperch Hyperprosopon ellipticum

Slender sole Eopsetta exilis

Speckled sanddab Citharichthys stigmaeus

Spotted cuskeel Chilara taylori

Spotted ratfish Hydrolagus colliei

Spotted sand bass Paralabrax maculatofasciatus

Squarespot rockfish Sebastes hopkinsi

Starry rockfish Sebastes constellatus

Striped seaperch Embiotoca lateralis

Stripetail rockfish Sebastes saxicola

Swell shark Cephaloscyllium ventriosum

Common Name Scientific Name

Swordspine rockfish Sebastes ensifer

Thornback Platyrhinoidis triseriata

Threadfin bass Pronotogrammus multifasciatus

Treefish Sebastes serriceps

Tube-snout Aulorhynchus flavidus

Vermilion rockfish Sebastes miniatus

Walleye surfperch Hyperprosopon argenteum

White seabass Atractoscion nobilis

White surfperch Phanerodon furcatus

Whitespeckled rockfish Sebastes moseri 

Widow rockfish Sebastes entomelas

Wolf-eel Anarrhichthys ocellatus

Yelloweye rockfish Sebastes ruberrimus

Yellowtail Seriola lalandi

Yellowtail rockfish Sebastes flavidus

Zebra goby Lythrypnus zebra

Zebraperch Hermosilla azurea

Unidentified blennies Family Blenniidae

Unidentified gunnel Family Pholidae

Unidentified kelpfishes Family Clinidae

Unidentified pipefishes Syngnathus spp.

Unidentified poachers Family Agonidae

Unidentified rockfish Sebastes spp.

 juveniles 

Unidentified ronquils Family Bathymasteridae

Unidentified sanddabs Citharichthys spp.

Unidentified sculpins Family Cottidae 

Unidentified silversides Family Atherinidae

Unidentified fish species 

 

TABLE 1. (cont.) Common and scientific names of fishes observed in these studies. TABLE 2. Mean length of selected species at platform bottoms and shell mounds, 1996–2001.

 Species Location Holly Irene Grace Hidalgo Hermosa Harvest Gail

 LINGCOD bottom — 22.6 30.4 34.7 — 32.7 —

 shell mound — 19.1 30.2 22.2 — 28.8 —

 t — 7.04 0.15 7.57 — 2.24 —

 d.f. — 869 124 222 — 49 —

 significant@α=.05 — * — * — * —

 PAINTED bottom — 15.6 — 12.7 — — —

 GREENLING shell mound — 13.5 — 11.9 — — —

 t — 3.35 — 0.93 — — —

 d.f. — 175 — 80 — — —

 significant@α=.05 — * — — — — —

 STRIPED bottom — — — 17.8 — 22.1 21.3

 ROCKFISH shell mound — — — 14.4 — 21.3 17.4

 t — — — 3.11 — 1.75 5.08

 d.f. — — — 82 — 341 119

 significant@α=.05 — — — * — — *

 COPPER bottom 22.2 20.7 — — — — —

 ROCKFISH shell mound 20 18.4 — — — — —

 t 22.23 5.95 — — — — — d.f. 327 1,400 — — — — —

 significant@α=.05 * * — — — — —

 PINKROSE bottom — — — — — — 20.2

 ROCKFISH shell mound — — — — — — 14.2

 t — — — — — — 141.2

 d.f. — — — — — — 278

 significant@α=.05 — — — — — — *

GREENBLOTCHED bottom — — — — — — 26.0

 ROCKFISH shell mound — — — — — — 17.5

 t — — — — — — 8.86

 d.f. — — — — — — 432

 significant@α=.05 — — — — — — *

 FLAG bottom — — 17.4 — — — —

 ROCKFISH shell mound — — 13.7 — — — —

 t — — 3.23 — — — —

 d.f. — — 136 — — — —

 significant@α=.05 — — * — — — —

 HALFBANDED bottom 12.5 11.6 16.2 12.3 13.5 — —

 ROCKFISH shell mound 7.0 7.0 14.9 10.4 11.7 — —

 t 7.23 35.6 32.8 32.33 31.37 — —

 d.f. 438 6,356 15,230 13,158 10,288 — —

 significant@α=.05 * * * * * * *
T-4

TABLES

T-5

TABLES

TABLE 3. Total numbers and densities (fishes per 100m2) of all fishes observed at 

Platform Hidalgo and North Reef, 1996–2001.

PLATFORM HIDALGO NORTH REEF 

Species Total Density Species Total Density

Unidentified rockfish YOY 13,462 103 Unidentified rockfish YOY 4,786 54

Halfbanded rockfish 13,194 101 Pygmy rockfish 1,684 19

Widow rockfish YOY 828 6 Widow rockfish YOY 886 10

Greenspotted rockfish 617 5 Halfbanded rockfish 575 7

Flag rockfish 266 2 Greenspotted rockfish 370 4

Lingcod 224 2 Sebastomus group 187 2

Painted greenling 218 2 Yellowtail rockfish 118 1

Widow rockfish 95 <1 Vermilion rockfish 100 1

Bocaccio YOY 91 <1 Squarespot rockfish 72 <1

Greenstriped rockfish 84 <1 Shortspine combfish 69 <1

Greenblotched rockfish 69 <1 Greenstriped rockfish 61 <1

Bocaccio 56 <1 Unidentified rockfish 52 <1

Rosy rockfish 56 <1 Lingcod 49 <1

Vermilion rockfish 44 <1 Blackeye goby 43 <1

Canary rockfish 41 <1 Unidentified fish 40 <1

Squarespot rockfish 33 <1 Pink surfperch 39 <1

Swordspine rockfish 27 <1 Starry rockfish 38 <1

Sebastomus sp. 27 <1 Canary rockfish 38 <1

Pacific sanddab 17 <1 Greenblotched rockfish 38 <1

Pygmy rockfish 16 <1 Rosy rockfish 34 <1

Sharpchin rockfish 16 <1 Unidentified combfish 27 <1

Unidentified combfish 14 <1 Pacific argentine 23 <1

Cowcod 12 <1 Swordspine rockfish 19 <1

Yelloweye rockfish 12 <1 Flag rockfish 18 <1

Kelp greenling 10 <1 Bocaccio 16 <1

Unidentified rockfish 9 <1 Cowcod 12 <1

Unidentified sanddab 7 <1 Widow rockfish 10 <1

Starry rockfish 7 <1 Unidentified flatfishes 10 <1

Shortspine combfish 6 <1 Unidentified ronquils 5 <1

Unidentified poacher 5 <1 Speckled rockfish 4 <1

Yellowtail rockfish 5 <1 Yelloweye rockfish 4 <1

Unidentified fishes 5 <1 Unidentified sanddab 3 <1

Pink surfperch 4 <1 Bank rockfish 3 <1

Bank rockfish 2 <1 Unidentified poacher 2 <1

Unidentified ronquil 2 <1 Ratfish 2 <1

Unidentified sculpin 1 <1 Olive rockfish 2 <1

Ratfish 1 <1 Unidentified Cusk-eel 1 <1

Copper rockfish 1 <1 Kelp greenling 1 <1

Stripetail rockfish 1 <1 Painted greenling 1 <1

California scorpionfish 1 <1 Bluebarred prickleback 1 <1

Longspine combfish 1 <1 Sharpchin rockfish 1 <1

 Longspine combfish 1 <1

TOTAL 29,587 226 TOTAL 9,445 108

Minimum number of species 34 Minimum number of species 34 

Total rockfish YOY 14,381 109 Total rockfish YOY 5,672 65

Total rockfishes 29,071 217 Total rockfishes 9,128 99

Rockfish YOY comprised 48.6% of all fishes surveyed. Rockfish YOY comprised 60% of all fishes surveyed.

All rockfishes comprised 98.3% of all fishes surveyed. All rockfishes comprised 96.6% of all fishes surveyed.

Species observed only at Platform Hidalgo: California scorpionfish, copper and stripetail rockfishes.

Species observed only at North Reef: Blackeye goby, bluebarred prickleback Pacific argentine, speckled sanddab. 

TABLE 4. Total numbers of all fishes observed at the deeper, below 30 m, depths at seven 

platforms and 80 natural outcrops, 1996–2001.

ALL PLATFORMS 

Species Total Species Total Species Total

Unident. rockfish YOY 47,973 Pile perch 235 Splitnose rockfish 22

Halfbanded rockfish 46,831 Blackeye goby 222 Gopher rockfish 19

Widow rockfish YOY 10,902 Pacific sanddab 215 Pygmy rockfish 17

Shortbelly rockfish 7,443 Unidentified combfish 210 Yelloweye rockfish 16

Squarespot rockfish 3,834 Yellowtail rockfish 198 C-O turbot 15

Pacific sardine 3,308 Whitespeckled rockfish 196 Senorita 14

Blacksmith 2,796 Halfmoon 189 Darkblotched rockfish 14

Widow rockfish 2,540 Unidentified rockfish 184 Unidentified Rathbunella 12

Vermilion rockfish 2,288 Kelp rockfish 171 Cabezon 12

Blue rockfish 2,063 Rosy rockfish 167 California smoothtongue 11

Stripetail rockfish 2,037 Northern anchovy 159 Starry rockfish 11

Bocaccio YOY 1,910 Brown rockfish 142 Bank rockfish 11

Copper rockfish 1,836 Unidentified fishes 131 Speckled rockfish 7

Painted greenling 1,738 Chilipepper 122 Spotted ratfish 6

Greenspotted rockfish 1,595 Canary rockfish 113 Hornyhead turbot 5

Widow/squarespot rockfish1,575 Unidentified flatfish 103 Unidentified cuskeel 4

Lingcod 1,486 Cowcod 98 Phanerodon sp. 4

Calico rockfish 1,311 Unidentified seaperch 95 Unidentified skate 4

Shiner perch 1,161 Swordspine rockfish 73 Wolf-eel 3

Bocaccio 742 Kelp greenling 66 Unidentied eelpout 3

Flag rockfish 735 Kelp bass 55 Rex sole 2

Sharpnose seaperch 621 California sheephead 53 Bluebanded goby 2

Greenblotched rockfish 600 Longspine combfish 43 California halibut 2

Unidentified sanddab 576 Dover sole 41 Redbanded rockfish 2

Greenstriped rockfish 572 Opaleye 38 Pink rockfish 2

California scorpionfish 560 Garibaldi 36 Pacific electric ray 2

Pacific hake 531 Honeycomb rockfish 35 Mola 1

Sebastomus sp. 371 Spotted cuskeel 33 White seaperch 1

Jack mackerel 348 Treefish 33 Whitespeckled rockfish/ 

Sharpchin rockfish 346 Unidentified ronquil 30 Chilipepper 1

Pinkrose rockfish 331 Rubberlip seaperch 30 Bocaccio/chilipepper 1

Olive rockfish 312 Pacific mackerel 30 Shortspine thornyhead 1

Pink seaperch 308 Blackgill rockfish 28 California tonguefish 1

Unidentified poacher 296 Unidentified sculpin 26 

Shortspine combfish 245 Mexican rockfish 25 

TOTAL 155,973 

Minimum number of species 85 

Total rockfishes 139,855 

All rockfishes comprised 89.7% of all fishes surveyed. 
T-6

TABLES

T-7

TABLES

TABLE 4. (cont.) Total numbers of all fishes observed at the deeper, below 30 m, depths at 

seven platforms and 80 natural outcrops, 1996–2001.

ALL NATURAL OUTCROPS 

Species Total Species Total Species Total

Widow rockfish YOY 87,238 Splitnose rockfish 214 Black perch 12

Squarespot rockfish 41,344 Pile perch 202 Calico rockfish 12

Pygmy rockfish 36,036 Greenblotched rockfish 167 Pacific hake 9

Shortbelly rockfish 35,439 Cowcod 146 Rubberlip seaperch 9

Halfbanded rockfish 26,169 Bocaccio YOY 146 Kelp rockfish 9

Swordspine rockfish 11,733 White seaperch 137 California halibut 7

Sebastomus spp. 7,648 Rathbunella sp 128 Unidentified prickleback 6

Widow rockfish YOY 6,635 Canary rockfish 127 Spotted cuskeel 4

Widow rockfish 6,245 Painted greenling 125 Dover sole 4

Blacksmith 4,744 Unidentified flatfish 123 Redbanded rockfish 4

Pink seaperch 4,495 Honeycomb rockfish 118 California lizardfish 4

Senorita 3,831 Copper rockfish 112 Jack mackerel 4

Rosy rockfish 2,459 Unidentified seaperch 111 Wolf-eel 3

Blue rockfish 2,274 Stripetail rockfish 106 Slender sole 3

Blackeye goby 2,123 Unidentified poacher 104 Bluntnose sixgill shark 3

Pacific sardine 2,070 Pacific argentine 104 Hornyhead turbot 3

Bank rockfish 1,781 Unidentified sanddab 104 Longnose skate 3

Pinkrose rockfish 1,433 Unidentified ronquil 85 White seabass 2

Speckled rockfish 1,285 Olive rockfish 85 Roughback sculpin 2

Greenspotted rockfish 1,094 Unidentified sculpin 73 Northern anchovy 2

Vermilion rockfish 945 Freckled rockfish 65 Rex sole 2

Unidentified rockfish 863 Yelloweye rockfish 65 Kelp greenling 2

Bocaccio 861 Treefish 64 Halfmoon 2

Unidentified combfish 728 Sharpchin rockfish 59 Unidentified pholid 2

Shortspine combfish 663 Shortspine thornyhead 49 English sole 2

Pinkrose rockfish 585 Swell shark 48 Unidentified turbot 2

Lingcod 580 Brown rockfish 40 Unidentified skate 2

Yellowtail rockfish 494 Darkblotched rockfish 38 Pacific electric ray 2

Greenspotted rockfish 462 Unidentified eelpout 36 Pacific sanddab 1

Starry rockfish 440 Gopher rockfish 35 Rainbow surfperch 1

Unidentified fish 381 Longspine combfish 31 California smoothtongue 1

Chilipepper 373 Island kelpfish 27 Bearded eelpout 1

Sharpnose seaperch 325 Blackgill rockfish 26 Unidentified cuskeel 1

Flag rockfish 309 Ocean whitefish 23 Phanerodon sp 1

Spotted ratfish 296 Threadfin bass 21 Bluebarred prickleback 1

California sheephead 237 Pink rockfish 17 C-O turbot 1

California scorpionfish 222 Pacific hagfish 14 Big skate 1

Whitespeckled rockfish 221 Bronzespotted rockfish 13 

 

GRAND TOTAL 298,379 

Minimum number of species 94 

Total rockfishes 276,034 

All rockfishes comprised 92.5% of all fishes surveyed.

TABLE 5. Twenty highest densities of rockfish young-of-the-year juveniles, 1996–2001 as observed from the Delta submersible. Platforms are listed in blue, natural outcrops in red. 

 Density of 

 Habitat Rockfish YOY

Site Year Type (fish per 100m2)

Hidden Reef 1999 Natural 1249.2

Platform Hermosa 1999 Midwater 993. 6

Platform Irene 1998 Midwater 935.4

Platform Harvest 1999 Midwater 555.1

Platform Irene 1999 Midwater 524.3

San Miguel Island 1995 Natural 520.5

Platform Grace 2001 Midwater 486.5

Platform Hidalgo 1997 Midwater 385.2

Potato Bank 1996 Natural 367.7

Platform Irene 1997 Bottom 363.8

Platform Grace 2000 Midwater 346.2

Platform Irene 1997 Midwater 344.1

North Reef 1995 Natural 338.7

Platform Holly 1999 Bottom 326.1

Platform Hidalgo 1999 Midwater 314.6

Platform Irene 2001 Midwater 306.2

San Nicolas Island 1996 Natural 302.9

San Miguel Island 1995 Natural 262.1

Santa Rosa Island 1995 Natural 227.1

Platform Harvest 1997 Midwater 225.6 

TABLE 6. Fish species observed as young-of-the-year juveniles at California oil/gas platforms.

Common Name Common Name

Bank rockfish Kelp bass* 

Black rockfish Kelp greenling*

Blackeye goby* Kelp rockfish*

Blackgill rockfish Lingcod*

Blacksmith* Olive rockfish

Blue rockfish* Pacific hake

Bluebanded goby* Painted greenling*

Bocaccio* Pinkrose rockfish*

Brown rockfish* Pygmy rockfish*

Cabezon* Rosy rockfish*

Calico rockfish* Sharpchin rockfish

Canary rockfish* Shortbelly rockfish*

Copper rockfish* Splitnose rockfish

Cowcod* Squarespot rockfish*

Flag rockfish* Starry rockfish*

Garibaldi* Stripetail rockfish*

Gopher/Black-and-Yellow rockfish* Treefish

Greenblotched rockfish* Vermilion rockfish*

Greenspotted rockfish* Widow rockfish*

Greenstriped rockfish* Yelloweye rockfish*

Halfbanded rockfish* Yellowtail rockfish

Halfmoon* Unidentified combfishes (Zaniolepis spp.)*

We also observed adult sarcastic fringehead, 

as well as unidentified blennies (Hypsoblennius 

spp.) and sculpins. Given the cryptic and sedentary nature of these species, we believe they 

arrived at platforms via larval recruitment. 

In addition, Carlisle et al. (1964) observed 

young-of-the-year black perch, pile perch, 

rubberlip seaperch, and white surfperch at 

Platform Hazel (removed in 1996).

*These species were observed as both newly settled juveniles and adults at platforms.
A-1

APPENDICES

APPENDIX 1. Platform Synopses

In this section, we give a brief summary of each of the California platforms. The platforms are listed from the most 

northwest, Irene, off Point Arguello, to Emmy in the southeast off Long Beach. 

Wherever possible, we have included the following information on each platform: (1) the original operator; (2) 

the current operator of record; (3) the date the platform was installed; (4) the first production date; (5) the platform’s 

distance from shore (including whether it is in state or outer continental shelf [OCS] waters); (6) the bottom depth of 

the platform; (7) the number of wells; (8) what the platform produces (oil and/or gas); (9) the platform jacket dimensions (generally at the seafloor [bottom]); (10) the size of the shell mound surrounding the platform; (11) the size of 

the platform’s footprint. This data was taken from California Resources Agency (1971), Manago and Williamson (1998), 

Holbrook et al. (2000), and Sea Surveyor Inc. (2001). We have also included a photograph of most of the platforms and 

their locations including latitude and longitude.

We follow this with a synopsis of the fish assemblages around each platform. When these summaries are based on our 

scuba and submersible surveys we include the years these surveys were conducted. Scuba surveys are midwater surveys 

except at the shallow water Platform Gina. Because of funding limitations, a number of platforms were surveyed only 

once and in a number of instances poor water visibility prevented complete coverage. Neither ExxonMobil nor Aera 

gave us permission to survey their platforms. In some instances, we were able to review videos that were taken during 

mandatory platform inspections. From these, we made a qualitative estimate of platform bottom fish assemblages for 

those platforms we were unable to survey.

IRENE 

Original operator: Union; current operator of record: Nuevo Energy; date 

installed: 1985; first production: 1987; distance from shore (miles): 4.7 (OCS); 

water depth: 73 m (242 ft.); number of well slots 72; produces: oil and gas; platform jacket dimensions: 47 x 56 m (155 x 185 ft.) (bottom); platform footprint 

(m2): 2,633; location: 120o43.45’N, 34o36.37’W.

Dates and types of surveys:

Scuba: 1995–2000

Submersible:

 Midwater Bottom Shell Mound

1995 x

1996 x x x

1997 x x x

1998 x x x

1999 x x x

2000 x x x

2001 x x x

Platform Irene’s midwaters consistently harbored large numbers of YOY 

(young-of-the-year) and older juvenile rockfishes. Bocaccio, blue, shortbelly, squarespot, treefish, and widow rockfishes, and the complex comprised of young black-and-yellow, copper, gopher, and kelp rockfishes, were abundant. 

Densities of these fishes were usually among the highest we observed around either platforms or natural outcrops. 

Young painted greenling, living on the jacket, were also quite abundant. During the 1998 El Niño, YOY blacksmith 

settled on the platform in large numbers. However, they were gone by the following year. Kelp greenling recruited as 

young-of-the-year in 1999; they swam to the platform bottom during the next year and were there through 2001.Two 

pelagic species, jack mackerel and Pacific sardine, were also occasionally seen in high numbers. The platform bottom had 

particularly high densities of halfbanded rockfish and YOY rockfishes, as well as subadult and adult copper, vermilion, 

calico, and brown rockfishes. Juvenile lingcod, pile perch and painted greenling were also very abundant and Pacific 

sanddab, canary and yellowtail rockfishes were frequently seen. On the shell mound, halfbanded and copper rockfish, as 

well as young lingcod were very common. Platform Irene is particularly noteworthy as it harbored far higher densities 

of young lingcod than did any other site (platform or natural outcrop) that we surveyed.

Opposite: Vermilion rockfish and assorted invertebrates at the bottom of Platform Grace. (Photograph by Donna Schroeder)
A-2

APPENDIIX 1

A-3

APPENDIIX 1

HIDALGO

Original operator: Chevron; current operator of record: Arguello Inc.; date installed: 1986; first production: 1991; 

distance from shore (miles): 5.9 (OCS); water depth: 130 m (430 ft.); number of well slots: 56; produces: oil and gas;

platform jacket dimensions: 78 x 53 m (257 x 176 ft.) (bottom); platform footprint (m2): 4,154; location: 34°29’N, 

120°42’W.

Dates and types of surveys:

Scuba: 1996–2000 

Submersible: 

 Midwater Bottom Shell Mound

1996 x x x

1997 x x x

1998 x x x

1999 x x x

2000 x x x

2001 x x x

We observed high densities of YOY and older juvenile rockfishes in the midwaters of Platform Hidalgo. A number of 

rockfishes, including blue, copper, gopher, kelp, olive, rosy, squarespot, and widow rockfishes and bocaccio were abundant. 

Halfmoon and young painted greenling were also common. Large numbers of YOY blacksmith recruited to the platform 

during 1998 and remained there through 2001. Similarly, kelp greenling young settled during 1999, and some remained 

through 2001. Jack mackerel and northern anchovy were occasional visitors. The bottom of this platform was dominated 

by halfbanded, greenspotted, and flag rockfishes, YOY rockfishes, and lingcod. Flag rockfish density was higher than at 

any natural outcrop or other platform. Other important species included canary, greenstriped, vermilion, and widow 

rockfishes and painted greenling. On the shell mounds, we noted extremely large numbers of halfbanded rockfish. Both 

juvenile and adult lingcod were also abundant. 

HARVEST

Original operator: Texaco; current operator of record: Arguello Inc.; date installed: 1985; first production: 1991; 

distance from shore (miles): 6.7 (OCS); water depth: 205 m (675 ft.); number of well slots: 50; produces: oil and gas;

platform jacket dimensions: 61 x 97 m (200 x 319 ft.) (bottom); platform footprint (m2): 5,859; location: 34°28’N, 

120°40’W.

Dates and types of surveys:

Scuba: 1996–2000 

Submersible: 

 Midwater Bottom Shell Mound

1996 x

1997 x x x

1998 x x x

1999 x x x

2000 x x x

2001

As on most of the other platforms we surveyed, YOY and somewhat older rockfishes characterized the midwaters 

of Platform Harvest. Of these, bocaccio, as well as blue, olive, squarespot, and widow rockfishes were most abundant. 

Young painted greenling , as well as halfmoon, also were seen frequently. Blacksmith were abundant, they had recruited 

in 1998 as YOY and remained at the platform through 2001. Large numbers of kelp greenling settled from the plankton 

in 1999. Pelagic species, such as northern anchovy and Pacific sardine, were occasional visitors. In the deeper midwaters, we saw many sharpchin and whitespeckled rockfishes. Stripetail, greenstriped, greenspotted, and greenblotched 

rockfishes and lingcod were commonly seen on the bottom. Stripetail, greenstriped and sharpchin rockfishes were most 

abundant on the shell mounds.

HERMOSA

Original operator: Chevron; current operator of record: Arguello Inc.; date installed: 1985; first production: 1991; 

distance from shore (miles): 6.8 (OCS); water depth: 183 m (603 ft.); number of well slots: 48; produces: oil and gas;

platform jacket dimensions: 61 x 85 m (200 x 280 ft.) (bottom); platform footprint (m2): 5,142; location: 34°27’N, 

120°38’W.

Dates and types of surveys:

Scuba: 1996–2000 

Submersible: 

 Midwater Bottom Shell Mound 

1996 x x 

1997 x x x

1998 x x x

1999 x x x

2000 x x x 

2001

Platform Hermosa’s midwaters are noteworthy as rockfish 

nursery grounds. They harbored the second highest densities of YOY rockfishes of any site we surveyed (second only to 

Hidden Reef) (Table 5). Bocaccio, blue, olive, squarespot, widow, and whitespeckled rockfishes, as well as painted greenling 

were very abundant. Blacksmith and halfmoon were also typical species. As at many other platforms, in 1999 kelp greenling 

settled out of the plankton at Platform Hermosa. Jack mackerel and northern anchovy were also common. While halfbanded 

rockfish dominated the bottom assemblage, greenspotted rockfish were also abundant. Halfbanded rockfish also were the 

most abundant species on the shell mound.

HONDO

Original operator: Exxon; current operator of record: ExxonMobil; date installed: 1976; first production: 1981; 

distance from shore (miles): 5.1 (OCS); water depth: 255 m (842 ft.); number of well slots: 28; produces: oil and gas;

platform jacket dimensions: 68 x 68 m (225 x 225 ft.) (bottom); platform footprint (m2): 4,649; location: 34°23’N, 

120°07’W.

Exxon and ExxonMobil did not allow us to survey this platform. However, we were able to review part of an inspection tape made at and near the bottom of Platform Hondo (Divecon International, 3 August 2002). Based on this, a 

number of rockfishes, including bank, darkblotched, pinkrose, widow and probably blackgill, live around the bottom 

of Platform Hondo. Darkblotched rockfish appeared to be particularly abundant. 

HARMONY

Original operator: Exxon; current operator of record: ExxonMobil; date installed: 1989; first production: 1993; 

distance from shore (miles): 6.4 (OCS); water depth: 363 m (1,198 ft.); number of well slots: 60; produces: oil and gas;

platform jacket dimensions: 91 x 117 m (300 x 385 ft.) (bottom); platform footprint (m2): 10,606; location: 34°22’N, 

120°10’W.

Exxon and ExxonMobil did not allow us to survey this platform.

HERITAGE

Original operator: Exxon; current operator of record: ExxonMobil; distance from shore (miles): 8.2 (OCS); water 

depth: 326 m (1,075 ft.); number of well slots: 60; produces: oil and gas; location: 34°21’N, 120°16’W.

Exxon and ExxonMobil did not allow us to survey this platform. We reviewed part of an ROV inspection of this 

platform (Divecon International, 2 August 2002) and noted blackgill, darkblotch, pinkrose, and widow rockfish at or 

near the bottom.
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APPENDIIX 1

A-5

APPENDIIX 1

HOLLY

Original operator: Atlantic Richfield, current operator of record: Venoco, date installed: 1966; first production: 1966; distance from shore (miles): 1.8 (state); water depth: 64 m (211 ft.); number of well slots: 30; produces: oil and gas; platform jacket 

dimensions: 18 x 30 m (60 by 100 ft.) (surface), 36 x 48 m (119 by 158 ft.) (bottom); location: 34°22’N, 119° 52’W.

Dates and types of surveys:

Scuba: 1995–2000 

Submersible: 

 Midwater Bottom Shell 

Mound 

1995 x

1996 x x 

1997 x x x

1998 x x x

1999 x

2000

2001 x x x

The midwaters around Platform Holly were populated 

by large numbers of blue, copper, kelp, olive, squarespot, 

and widow rockfishes and bocaccio. With the exception of 

kelp rockfishes, most of these fishes were juveniles. Blacksmith, halfmoon, kelp bass, painted greenling, pile perch, 

and sharpnose seaperch were also abundant. Schools of 

jack mackerel and Pacific sardines were also noted. The 

platform bottom fish assemblage was characterized by 

YOY widow rockfish, calico, vermilion, halfbanded, and 

copper rockfishes, sharpnose seaperch and blackeye goby. 

Most of the vermilion and copper rockfishes were juveniles 

and subadults. Calico, vermilion, and copper rockfishes were 

the most abundant species on the shell mound. 

C

Original operator: Union Oil; current operator of record: Nuevo Energy; date installed: 1977; first production: 1977; 

distance from shore (miles): 5.7 (OCS); water depth: 58 m (192 ft); number of well slots: 60; produces: oil and gas;platform 

jacket dimensions: 40 x 48 m (133 x 158 ft.) (bottom); platform footprint (m2): 1,930; location: 34°19’N, 119°37’W.

Dates and types of surveys: 

Submersible:

 Midwater Bottom Shell Mound

2000 x (partial) x

Only part of the platform midwater was surveyed and olive 

rockfish were most abundant. On the shell mound, vermilion, 

halfbanded, and calico rockfishes were most common, and blackeye goby, copper rockfish and painted greenling were also frequently 

encountered. A platform inspection video made on 23 September 

1999 (Stolt Comex Seaway) around the platform bottom showed 

large numbers of juvenile blue, brown, copper, olive, vermilion, 

and widow rockfishes and lingcod. Both juvenile and adult calico, 

gopher, halfbanded and kelp rockfishes and painted greenling were 

also present.

B

Original operator: Union Oil; current operator of record: Nuevo 

Energy; date installed: 1968; first production: 1969; distance from shore 

(miles): 5.7 (OCS); water depth: 58 m (190 ft.); number of well slots: 63; 

produces: oil and gas; platform jacket dimensions: 40 x 48 m (133 x 158 ft.) 

(bottom); platform footprint (m2): 1,930; location: 34°19’N, 119°37’W.

Dates and types of surveys: 

Submersible:

 Midwater Bottom Shell Mound

2000 x

Juvenile widow rockfish, which had probably settled from the plankton in 1999, were abundant in the platform 

midwaters in 2000. Blacksmith, young blue, olive and kelp rockfishes, senorita and painted greenling were also common. 

We reviewed a video of a platform inspection (Stolt Comex Seaway, 21 September 1999) and noted large numbers of 

juvenile lingcod, blue, flag, and vermilion rockfishes as well as many juvenile and adult calico, gopher, halfbanded, kelp 

and rosy rockfishes and painted greenling. 

A

Original operator: Union Oil; current operator of record: Nuevo 

Energy; date installed: 1968; first production: 1969; distance from 

shore (miles): 5.8 (OCS); water depth: 57 m (188 ft.); number of well 

slots: 57; produces: oil and gas; platform jacket dimensions: 40 x 48 

m (133 x 158 ft.) (bottom); platform footprint (m2): 1,930; location: 

34°19’N, 119°36’W. 

Dates and types of surveys: 

Submersible: 

 Midwater Bottom Shell Mound

2000 x

Blacksmith, blue and olive rockfishes were most abundant in the platform midwaters during 2000. Halfmoon, kelp 

bass and painted greenling were also common. Due to poor visibility, we were unable to survey the bottom and shell 

mound of Platform A during 2000. However, we reviewed a 2001 platform inspection video tape (Divecon International 

2001) conducted with a remotely operated vehicle. That tape showed that there were large numbers of fishes, primarily 

rockfishes, around the platform bottom. These included many subadult vermilion and copper rockfishes, as well as 

blue, calico, gopher, kelp, and juvenile widow rockfishes, lingcod and painted greenling. 

HILLHOUSE

Original operator: Sun Oil; current operator of record: Nuevo 

Energy; date installed: 1969; first production: 1970; distance from 

shore (miles): 5.5 (OCS); water depth: 58 m (190 ft.); number of well 

slots: 60; produces: oil and gas; platform jacket dimensions: 49 x 40 m 

(163 x 133 ft.) (bottom); location: 34°19’N, 119°36’W.

Dates and types of surveys: 

Submersible: 

 Midwater Bottom Shell Mound 

2000 x

Blacksmith and painted greenling were the most abundant species in the platform midwaters. Poor water visibility 

prevented us from surveying the platform bottom and shell mound. We reviewed a videotape made during an ROV 

platform inspection survey (Divecon International, 26 August 2001) and, although this too was conducted during poor 

visibility, noted juvenile copper, flag, and vermilion rockfishes, as well as painted greenling and pile perch. 
A-6

APPENDIIX 3

A-7

APPENDIIX 3

HENRY

Current operator of record: Nuevo Energy; date installed: 

1979; first production: 1980; distance from shore (miles): 4.3 

(OCS); water depth: 52 m (173 ft.); number of well slots: 24; 

produces: oil and gas; platform jacket dimensions: 45 x 33 m 

(149 x 110 ft.) (bottom); size of shell mound: 9 m (19 ft) high, 

circular and 76 m (250 ft.) in diameter; platform footprint (m2): 

1,505; location: 34°19’N, 119°33’W.

Dates and types of surveys: 

Submersible: 

 Midwater Bottom Shell Mound

2000 x

Halfmoon, blacksmith and kelp bass were common in the midwaters of Platform Henry.

HOUCHIN

Original operator: Phillips Petroleum/Continental Oil/

Cities Services Oil; current operator of record: Pacific Operators Offshore; date installed: 1968; first production: 1969; distance from shore (miles): 4.1 (OCS); water depth: 49 m (163 

ft.); number of well slots: 60; produces: oil and gas; platform 

jacket dimensions: 38 x 38 m (125 x 125 ft.) (bottom); size of 

shell mound: 6 m (21 ft.) high, circular and 85 m (280 ft.) in 

diameter; 1,435; location: 34°20’N, 119°33’W.

Dates and types of surveys: 

Submersible: 

 Midwater Bottom Shell Mound

2000 x

Painted greenling and halfmoon were the most abundant species in the platform midwaters.

HOGAN

Original operator: Phillips Petroleum/Continental Oil/Cities Services Oil; current operator of record: Pacific 

Operators Offshore; date installed: 1967; first production: 1968; distance from shore (miles): 3.7 (OCS); water depth: 

47 m (154 ft.); number of well slots: 66; produces: oil and gas; platform jacket dimensions: 38 x 38 m (125 x 125 ft.) 

(bottom); platform footprint (m2

): 1,435; location: 34°20’N, 119°32’W.

Dates and types of surveys: 

Submersible: 

 Midwater Bottom Shell Mound

2000 x

The midwaters around Platform Hogan were important habitat for a diverse 

fish assemblage. Blacksmith, blue and olive rockfishes, painted greenling, sharpnose 

seaperch, pile perch and California sheephead were all common species. 

 

HABITAT

Original operator: Texaco; current operator of record: Nuevo Energy; date installed: 1981; first production: 1993; distance 

from shore (miles): 7.8 (OCS); water depth: 88 m (290 ft.); 

number of well slots: 24; produces: gas; platform jacket dimensions: 60 x 38 m (199 x 125 ft.) (bottom); platform footprint 

(m2): 2,284; location: 34°17’N, 119°35’W.

Dates and types of surveys: 

Submersible: 

 Midwater Bottom Shell Mound

1995 x (partial)

2000 x

YOY widow rockfish, blacksmith, and one-year-old widow rockfish dominated the midwater at Platform Habitat. 

Blue and kelp rockfishes and painted greenling were also common species.

GRACE

Original operator: Standard Oil; current operator of record: Venoco; date installed: 1979; first production: 1980; 

distance from shore (miles): 10.5 (OCS); water depth: 96 m (318 ft.); number of well slots: 48; produces: Grace is a 

non-producing platform; platform jacket dimensions (at surface and at bottom): 27 x 44 m (90 by 145 ft.) (surface), 

48 x 65 m (158 x 213 ft.) (bottom); size of shell mound: 4 m (13 ft.) high, oval, 61 x 118 m (200 x 390 ft.), oriented in 

a northwest-southeast direction; platform footprint (m2): 3,090; location: 34°10’N, 119°28’W.

Dates and types of surveys:

Scuba: 1996–2000 

Submersible: 

 Midwater Bottom Shell Mound

1996 x x

1997 x x x

1998 x x

1999 x x x

2000 x x x

2001 x x x

The midwaters around Platform Grace contained very large 

numbers of young rockfishes. Most of these rockfishes recruited 

between 1999 and 2001.YOY widow rockfish and bocaccio, juvenile squarespot, blue and widow rockfishes, bocaccio and juvenile and adult blacksmith were very common. Painted greenling, 

sharpnose seaperch, jack mackerel and young flag rockfish were also frequently encountered. Halfbanded rockfish were 

the most abundant species around the platform bottom. Juvenile widow, vermilion, and flag rockfishes and bocaccio 

were also abundant. Many of these individuals had settled out of the plankton at the platform in 1999 and had remained 

there. Squarespot and greenspotted rockfishes, young lingcod, and sanddabs were also common. Over the shell mounds, 

halfbanded rockfish and shiner perch were the most abundant species. Pink seaperch, sanddabs, YOY bocaccio, young 

lingcod, juvenile greenspotted, flag and vermilion rockfishes were also characteristic species.
A-8

APPENDIIX 1

A-9

APPENDIIX 1

GILDA

Original operator: Union Oil; Current operator of record: 

Nuevo Energy; date installed: 1981; first production: 1981; distance from shore (miles): 8.8 (OCS); water depth: 62 m (205 

ft.); number of well slots: 96; produces: oil and gas; platform 

jacket dimensions: 45 x 52 m (150 x 170 ft.) (bottom); platform 

footprint (m2): 2,342.location: 34°10’N, 119°25’W.

Dates and types of surveys:

Scuba: 1995–2000 

Submersible:

 Midwater Bottom Shell Mound

2000 x

Blacksmith, halfmoon, kelp bass, opaleye, senorita, as well 

as YOY and juvenile blue, olive, squarespot and widow rockfishes and bocaccio were abundant in the midwater of this 

platform. Many of these rockfishes recruited from the plankton as YOYs during 1999. Due to poor visibility, we were 

unable to survey the bottom and shell mound of Platform Gilda during 2000. However, we reviewed a 2001 platform 

inspection video tape (Divecon International 2001) conducted with a remotely operated vehicle. That tape showed 

high densities of calico and juvenile vermilion rockfishes, as well as blue, brown, copper, halfbanded, olive, and widow 

rockfishes. Kelp greenling, lingcod, Pacific sanddab, and painted greenling were also noted.

GAIL

Original operator: Standard Oil; current operator of record: Venoco; date installed: 1987; first production: 1988; 

distance from shore (miles): 9.9 (OCS); water depth: 224 m (739 ft.); number of well slots: 36; produces: oil and gas;

platform jacket dimensions: 21 x 52 m (70 x 170 ft.) (surface), 60 x 90 m (197 x 297 ft.) (bottom); platform footprint 

(m2): 5,327; location: 34°07’N, 119°24’W.

Dates and types of surveys:

Scuba: 1996–2000 

Submersible: 

 Midwater Bottom Shell Mound

1996 x x

1997 x x x

1998 x

1999 x x x

2000 x x x

2001 x x x

Blacksmith, halfmoon, kelp bass and a variety of young 

rockfishes, including bocaccio, blue, flag, olive, and widow, 

characterized the midwaters of this platform. Most of the young 

rockfishes settled from the plankton in 1999. The platform bottom fish assemblage was dominated by adult bocaccio, 

greenblotched, greenspotted, stripetail and pinkrose rockfishes. Of particular interest, we observed higher densities of 

both adult cowcod and bocaccio at the bottom of Platform Gail than at any natural outcrop or other platform. The 

shell mound at Platform Gail was characterized by stripetail, pinkrose, greenblotched and greenstriped rockfishes. On 

one occasion, large numbers of juvenile hake were observed, on another northern anchovies were abundant.

GINA

Original operator: Union Oil; current operator of record: Nuevo Energy; date installed:1980; first production: 1982; 

distance from shore (miles): 3.7 (OCS); water depth: 29 m (95 ft.); number of well slots: 15; produces: oil and gas; platform jacket dimensions: 28 x 20 m (94 x 65 ft.) (bottom); shell mound: 4 m (13 ft.) high, oval, 45 x 64 m (150 x 210 

ft.), oriented in a northwest-southeast direction; platform footprint (m2): 561; location: 34°07’N, 119°16’W.

Dates and types of surveys:

Scuba: 1995–2000

Platform Gina had the highest species richness (47) of any platform surveyed using scuba. Blacksmith dominated 

the assemblage, comprising 38% of all fishes observed. A close second was kelp bass, which counted for 31% of all fishes 

observed. Platform Gina had the highest number and density of surfperches of any platform, and was the only site 

where rubberlip surfperch formed part of the assemblage. The shell mound habitat at this platform provided excellent 

habitat for many species of recruiting rockfishes, where 13 species were observed. However, despite being present at 

every other surveyed platform, no widow or bocaccio juveniles were observed at Platform Gina. Pelagic species that 

characterized this assemblage include yellowtail, barracuda, and jackmackerel.

EDITH

Original operator: Standard Oil; current operator of record: 

Nuevo Energy; date installed: 1983; first production: 1984; distance 

from shore (miles): 8.5 (OCS); water depth: 49 m (161 ft.); number 

of well slots: 72; produces: oil and gas;platform jacket dimensions:

58 x 50 m (190 x 165 ft.) (bottom); platform footprint (m2): 

2,879; location: 33°35’N, 118°08’W.

Dates and types of surveys: 

Submersible:

 Midwater Bottom Shell Mound

1998 x x x

Blacksmith, halfmoon, opaleye, sheephead and garibaldi 

characterized the midwater fish assemblage at Platform Edith. 

Very high densities of California scorpionfish, along with sharpnose seaperch, blacksmith and blackeye goby were found 

at the platform bottom. California scorpionfish were also extremely abundant on the shell mound.

ELLEN

Original operator: Shell Oil; current operator of record: Aera Energy; date installed: 1980; first production: 1981; 

distance from shore (miles): 8.6 (OCS); water depth: 80 m (265 ft.); number of well slots: 80; produces: oil and gas; platform 

jacket dimensions: 45 x 56 m (147 x 186 ft.) (bottom); platform footprint (m2): 2,511; location: 33°34’N, 118°07’W.

Aera did not allow us to survey this platform. We reviewed 

a tape of a platform inspection carried out with a remotely operated vehicle (Divecon International, 7 September 2001) and 

observed very high densities of flag, halfbanded, squarespot 

and honeycomb rockfishes. We also saw a number of young 

vermilion rockfish. In the platform midwater, from about 61 

m (200 ft) and deeper, there were very large numbers of young 

rockfishes, including both squarespots and widows.
A-10

APPENDIIX 1

A-11

ELLY

Original operator: Shell Oil; current operator of record: Aera Energy; 

date installed: 1980; first production: n/a; distance from shore (miles): 8.6 

(OCS); water depth: 77 m (255 ft.); number of well slots: n/a; produces: 

Elly is a processing facility for Ellen and Eureka; platform jacket dimensions: 48 x 61 m (159 x 202 ft.) (bottom); platform footprint (m2): 

2,949; location: 33°35’N, 118°07’W.

Aera did not allow us to survey this platform. We reviewed a tape 

of a platform inspection carried out with a remotely operated vehicle 

(Divecon International, 9 September 2001) and observed high densities 

of young vermilion and young widow rockfishes, as well as many flag, 

honeycomb, olive, and squarespot rockfishes, and lingcod.

EUREKA

Original operator: Shell Oil; current operator of record: Aera 

Energy; date installed: 1984; first production: 1985; distance from 

shore (miles): 9.0 (OCS); water depth: 212 m (700 ft.); number of well 

slots: 60; produces: oil and gas; platform jacket dimensions: 54 x 85 

m (179 x 282 ft.) (bottom); platform footprint (m2): 4,635; location: 

33°33’N, 118°06’W.

Aera did not allow us to survey this platform. We reviewed a tape of a 

platform inspection carried out with a remotely operated vehicle (Divecon 

International, 5 September 2001) and observed large numbers of pinkrose and juvenile darkblotched rockfishes, as well as juvenile and subadult 

bocaccio and widow rockfish. Also present were flag, greenblotched and 

greenspotted, and perhaps speckled, rockfishes and lingcod. 

EVA

Original operator: Union Oil Company; current operator of 

record: Nuevo Energy; date installed: 1964; first production: 1966; 

distance from shore (miles): 1.8 (state); water depth: 17 m (57 ft.); 

number of well slots: 39; produces: oil and gas; location: 33°39’N, 

118°03’W.

EMMY

Original operator: Signal Oil and Gas Company; current operator 

of record: Aera Energy; date installed: 1963; first production: 1963; 

distance from shore (miles): 1.2 (state); water depth: 14 m (47 ft.); 

number of well slots: 53; produces: oil and gas; location: 33°39N, 

118°02’W.

Aera did not allow us to survey this platform.

APPENDIX 2 

Density of fishes observed during the oil/gas platform scuba surveys off central and southern California. Platforms 

are listed from northwest to southeast. Density is in fish per 100 m2, “<” means “less than.”

Common name Irene Hidalgo Harvest Hermosa Holly Grace Gilda Gail Gina

Barred sand bass 0.8

Black rockfish <0.1 <0.1 <0.1 <0.1

Black-and-yellow rockfish <0.1 <0.1 <0.1 

Blackeye goby <0.1 <0.1 <0.1 0.2 4.0

Blacksmith 1.6 16.2 20.0 8.5 20.9 71.3 57.4 77.4 51.3

Blue rockfish 32.3 3.8 18.9 7.5 36.3 5.3 9.8 3.9 1.3

Bluebanded goby <0.1

Bocaccio 9.5 0.1 3.7 0.8 36.6 2.7 5.0 5.9

Brown rockfish <0.1 <0.1 <0.1 <0.1

Bull sculpin <0.1

Cabezon 0.1 0.1 0.2 0.2 0.1 <0.1 0.1 <0.1 1.1

Calico rockfish <0.1 0.6

California barracuda 0.4 <0.1 0.8

California scorpionfish <0.1 <0.1 0.1

California sheephead <0.1 <0.1 0.1 <0.1 0.3

C-O turbot <0.1

Copper rockfish 0.2 0.2 0.1 0.1 0.8 0.1 <0.1 <0.1 <0.1

Copper 6.1 4.7 3.1 1.5 0.7 0.8 0.4 0.1 0.2

 -complex juv. rockfishes

Garibaldi <0.1 0.1 <0.1 0.1

Giant kelpfish <0.1 

Gopher rockfish <0.1 <0.1 <0.1 <0.1 0.1 <0.1 <0.1 <0.1 <0.1

Grass rockfish <0.1 <0.1 <0.1 0.2 <0.1

Halfbanded rockfish 0.6

Halfmoon <0.1 1.3 0.3 0.9 3.1 2.2 16.7 13.7 2.4

Jackmackerel 69.3 22.1 8.0 34.5 6.1 6.3 0.2 9.6

Kelp bass <0.1 0.5 6.1 1.8 42.9

Kelp greenling 0.1 0.4 0.6 0.4 0.1 0.1 0.1 0.1 <0.1

Kelp rockfish <0.1 0.7 0.2 0.1 3.7 1.5 0.6 0.4 0.4

Lingcod <0.1 0.1 <0.1 0.2

Mussel blenny <0.1 

Northern anchovy 6.3 7.4 7.4 

Ocean sunfish <0.1 

Ocean whitefish 0.0 0.8

Olive rockfish 0.6 0.7 4.5 3.8 2.5 0.3 1.6 0.9 0.2

Opaleye <0.1 2.4 0.1 2.5

Pacific butterfish <0.1 

Pacific mackerel <0.1 

Painted greenling 3.4 1.6 1.5 2.9 1.9 1.0 0.5 1.7

Pile perch 0.1 0.7 0.2 3.4

Rock wrasse 0.1 0.1

Rosy rockfish <0.1 0.5 <0.1 <0.1 <0.1 0.1

Rubberlip seaperch 0.6

Sarcastic fringehead <0.1 

Sardine 7.1 0.2 169.3 36.4 1.2 6.8

Senorita 3.6 0.2

Sharpnose seaperch 1.9 0.7 2.3
A-12

APPENDIIX 2

A-13

Common name Irene Hidalgo Harvest Hermosa Holly Grace Gilda Gail Gina

Shortbelly rockfish 57.0 

Spotted sand bass <0.1

Squarespot rockfish 4.7 8.4 3.3 49.0 5.4 13.3 0.2 4.2

Starry rockfish <0.1

Stripetail rockfish 1.2

Treefish 0.4 0.1 0.2 <0.1 0.1 0.2 0.1 0.1 0.1

Unidentified Atherinidae 12.3 

Unidentified Blenniidae <0.1 <0.1 <0.1

Unidentified Bothidae <0.1

Unidentified Clinidae <0.1 

Unidentified Cottidae <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

Unidentified fish species <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

Unidentified 4.9 8.6 1.2 0.1 1.6 0.5 0.2 0.1 0.6

 rockfish juveniles

Vermilion rockfish 0.1

White seaperch <0.1 <0.1 <0.1 1.5

Widow rockfish 141.4 10.8 46.9 15.5 54.9 2.7 1.5 <0.1

Wolf eel <0.1 <0.1

Yellowtail 0.1

APPENDIX 3 

Number and density of fishes observed in the midwaters, bottoms and shell mounds of oil/gas platforms off central and southern California. Platforms are listed geographically, from northwest to southeast. Species are ranked by 

number observed. YOY means “young-of-the-year”, those are fish that are less than one year old. Density is in fish per 

100 m2, “<” means “less than”. 

PLATFORM MIDWATERS

Because we could not estimate the lengths of the transects around Platforms Habitat and Gilda, no fish densities are presented.

PLATFORM IRENE (Surveyed 1995–2001) PLATFORM HIDALGO (Surveyed 1996–2001)

Species Number Density Species Number Density

Shortbelly rockfish YOY 7,300 378 Unidentified rockfish YOY 13,134 186

Unidentified rockfish YOY 4,133 214 Widow rockfish YOY 794 11

Widow rockfish YOY 2,310 120 Painted greenling 136 2

Pacific sardine 1,600 83 Bocaccio YOY 87 1

Bocaccio YOY 989 51 Halfbanded rockfish 34 <1

Widow rockfish 372 19 Widow rockfish 26 <1

Yellowtail rockfish 133 7 Flag rockfish 6 <1

Blacksmith 120 6 Kelp greenling 5 <1

Painted greenling 26 1 Yellowtail rockfish 5 <1

Copper rockfish 24 1 Squarespot rockfish 5 <1

Pile surfperch 11 <1 Pygmy rockfish 3 <1

Blue rockfish 5 <1 Unidentified fish 3 <1

Unidentified rockfish 2 <1 Greenspotted rockfish 2 <1

Kelp greenling 1 <1 Unidentified sculpin 1 <1

Lingcod 1 <1 Copper rockfish 1 <1

Olive rockfish 1 <1 Cabezon 1 <1

TOTAL 17,028 880 TOTAL 14,243 200

Minimum number of species 14 Minimum number of species 13 

Total rockfish YOY 14,732 763 Total rockfish YOY 14,015 198

Total rockfishes 15,269 790 Total rockfishes 14, 097 198

Rockfish YOY comprised 86.5% of all fishes surveyed. Rockfish YOY comprised 98.3% of all fishes surveyed.

All rockfishes comprised 89.7% of all fishes surveyed. All rockfishes comprised 98.9% of all fishes surveyed.

Cabezon in the midwater of Platform Holly.

DAN DUGAN
A-14

APPENDIIX 3

A-15

APPENDIIX 3

PLATFORM MIDWATERS, cont.

PLATFORM HARVEST (Surveyed 1996–2000) PLATFORM HERMOSA (Surveyed 1996–2000)

Species Number Density Species Number Density

Unidentified rockfish YOY 5,000 54 Unidentified rockfish YOY 17,242 199

Widow rockfish YOY 1,474 16 Widow rockfish YOY 1,140 16

Squarespot rockfish 1,246 14 Painted greenling 480 7

Painted greenling 289 3 Blue rockfish 436 5

Sharpchin rockfish 171 2 Widow rockfish 256 3

Whitespeckled rockfish 134 1 Squarespot rockfish 148 2

Widow rockfish 113 1 Whitespeckled rockfish 47 <1

Chilipepper 50 <1 Sebastomus sp. 42 <1

Sebastomus sp. 47 <1 Blacksmith 30 <1

Bocaccio YOY 43 <1 Bocaccio YOY 29 <1

Flag rockfish 26 <1 Unidentified rockfish 22 <1

Unidentified rockfish 23 <1 Pacific hake 19 <1

Unidentified fish 22 <1 Greenspotted rockfish 12 <1

Greenspotted rockfish 21 <1 Halfbanded rockfish 10 <1

Blue rockfish 18 <1 Flag rockfish 8 <1

Blacksmith 13 <1 Copper rockfish 5 <1

Kelp rockfish 5 <1 Cowcod 5 <1

Cabezon 2 <1 Unidentified fish 4 <1

Kelp greenling 2 <1 Unidentified sculpin 3 <1

Pacific sardine 2 <1 Cabezon 3 <1

Rosy rockfish 2 <1 Lingcod 3 <1

Shortbelly rockfish 2 <1 Sharpchin rockfish 3 <1

Blackeye goby 1 <1 Chilipepper 2 <1

Bocaccio 1 <1 Stripetail rockfish 2 <1

Calico rockfish 1 <1 Treefish 2 <1

Halfbanded rockfish 1 <1 Yelloweye rockfish 2 <1

Pygmy rockfish 1 <1 

Shortspine combfish 1 <1 TOTAL 19,955 232

Starry rockfish 1 <1 Minimum number of species 21 

Treefish 1 <1 Total rockfish YOY 18,411 215

Wolf-eel 1 <1 Total rockfishes 19,413 225

Yellowtail rockfish 1 <1 Rockfish YOY comprised 92.2% of all fishes surveyed.

 All rockfishes comprised 97.3% of all fishes surveyed.

TOTAL 8,715 91 

Minimum number of species 26 

Total rockfish YOY 6,517 70 

Total rockfishes 8,382 88 

Rockfish YOY comprised 74.8% of all fishes surveyed. 

All rockfishes comprised 96.2% of all fishes surveyed. 

PLATFORM MIDWATERS, cont.

PLATFORM HOLLY (Surveyed 1995–1998, 2001) PLATFORM A (Surveyed 2000)

Species Number Density Species Number Density

Pacific sardine 1,506 78 Blacksmith 421 28

Squarespot rockfish 315 16 Blue rockfish 336 22

Jack mackerel 287 15 Olive rockfish 126 8

Unidentified rockfish YOY 129 6 Halfmoon 25 2

Painted greenling 120 6 Kelp bass 17 1

Kelp rockfish 43 2 Painted greenling 11 <1

Copper rockfish 31 2 Unidentified seaperch 9 <1

Sharpnose seaperch 31 1 Sharpnose seaperch 9 <1

Yellowtail rockfish 22 1 Kelp rockfish 8 <1

Blacksmith 8 <1 Garibaldi 7 <1

Pile perch 7 <1 Unidentified rockfish YOY 6 <1

Brown rockfish 7 <1 Pile perch 5 <1

Calico rockfish 6 <1 California sheephead 4 <1

Gopher rockfish 6 <1 Blackeye goby 3 <1

Unidentified rockfish 6 <1 Unidentified fish 1 <1

Sebastomus sp. 4 <1 Unidentified rockfish 1 <1

Treefish 3 <1 

Unidentified sculpin 2 <1 TOTAL 989 61

Widow rockfish 2 <1 Minimum number of species 13 

Blue rockfish 2 <1 Total rockfish YOY 6 <1

Bocaccio YOY 2 <1 Total rockfishes. 477 30

Unidentified fish 2 <1 Rockfish YOY comprised <1% of all fishes 

 surveyed.

Lingcod 1 <1 All rockfishes comprised 48.2% of all fishes 

 surveyed.

Olive rockfish 1 <1 

Rubberlip seaperch 1 <1 

Widow rockfish YOY 1 <1 

Unidentified seaperch 1 <1 

 

TOTAL 2,546 127 

Minimum number of species 22 

Total rockfish YOY 122 6 

Total rockfishes 580 27 

Including the one time occurrence of Pacific sardine, YOY rockfishes comprised 4.8%, and all rockfishes comprised 

22.8% of all fishes surveyed.

Excluding Pacific sardines, YOY rockfishes comprised 11.7%, and all rockfishes comprised 55.8% of all fishes surveyed.
A-16

APPENDIIX 3

A-17

APPENDIIX 3

PLATFORM MIDWATERS, cont.

PLATFORM B (Surveyed 2000) PLATFORM C (Partially Surveyed 2000) 

Species Number Density Species Number Density

Widow rockfish 180 12 Olive rockfish 13 3

Blacksmith 124 8 Kelp rockfish 7 2

Blue rockfish 44 3 Pile perch 4 <1

Olive rockfish 26 2 Blue rockfish 4 <1

Kelp rockfish 16 1 Phanerodon sp. 3 <1

Senorita 13 <1 Vermilion rockfish 2 <1

Painted greenling 13 <1 Unidentified rockfish 2 <1

California sheephead 9 <1 Lingcod 1 <1

Kelp bass 6 <1 Unidentified fish 1 <1

Sharpnose seaperch 6 <1 Unidentified rockfish YOY 1 <1

Halfmoon 5 <1 

Pile perch 4 <1 TOTAL 38 5

Bluebanded goby 2 <1 Minimum number of species 7 

Cabezon 1 <1 Total rockfish YOY 1 <1

Copper rockfish 1 <1 Total rockfishes 27 5

Gopher rockfish 1 <1 All rockfishes comprised 71.1% of all fishes 

 surveyed.

Lingcod 1 <1 

Unidentified rockfish YOY 1 <1 

 

TOTAL 453 26 

Minimum number of species 17 

Total rockfish YOY 1 <1 

Total rockfishes 269 18 

Rockfish YOY comprised <1.0% of all fishes surveyed. 

All rockfishes comprised 59.4% of all fishes surveyed. 

 

PLATFORM HILLHOUSE (Surveyed 2000) PLATFORM HENRY (Surveyed 2000)

Species Number Density Species Number Density

Blacksmith 23 2 Halfmoon 57 6

Painted greenling 22 2 Blacksmith 20 2

Kelp bass 7 <1 Kelp bass 12 1

Olive rockfish 7 <1 Painted greenling 8 <1

Pile perch 3 <1 Kelp rockfish 1 <1

Kelp rockfish 1 <1 Unidentified rockfish YOY 1 <1

Lingcod 1 <1 

Phanerodon sp. 1 <1 TOTAL 99 9

Unidentified rockfish 1 <1 Minimum number of species 5 

 Total rockfish YOY 1 <1

TOTAL 66 4 Total rockfishes 2 <1

Minimum number of species 8 Rockfish YOY comprised 1% of all fishes surveyed.

Total rockfishes 9 <1 All rockfishes comprised 2% of all fishes surveyed.

 All rockfishes comprised 13.6% of all fishes 

 surveyed. 

 

PLATFORM MIDWATERS, cont.

PLATFORM HOUCHIN (Surveyed 2000) PLATFORM HOGAN (Surveyed 2000)

Species Number Density Species Number Density

Painted greenling 41 4 Blacksmith 75 7

Halfmoon 12 1 Blue rockfish 72 6

Kelp rockfish 9 <1 Olive rockfish 41 3

Blacksmith 4 <1 Painted greenling 28 3

Unidentified rockfish YOY 4 <1 Sharpnose seaperch 26 2

Garibaldi 3 <1 Pile perch 16 1

Pile perch 2 <1 California sheephead 15 1

California sheephead 1 <1 Kelp rockfish 4 <1

Olive rockfish 1 <1 Unidentified rockfish YOY 4 <1

Sharpnose seaperch 1 <1 Garibaldi 1 <1

Unidentified sculpin 1 <1 Kelp bass 1 <1

 Rubberlip seaperch 1 <1

TOTAL 99 6 

Minimum number of species 10 TOTAL 293 23

Total rockfish YOY 4 <1 Minimum number of species 11 

Total rockfishes 14 <1 Total rockfish YOY 4 <1

Rockfish YOY comprised 4% of all fishes surveyed. Total rockfishes 121 9

All rockfishes comprised 14% of all fishes surveyed. Rockfish YOY comprised 1.4% of all fishes surveyede

 All rockfishes comprised 41.3% of all fishes surveyed.

 

 

PLATFORM HABITAT (Partially Surveyed 1995, Surveyed 2000) 

Species Number Density

Widow rockfish YOY 470 

Blacksmith 122

Widow rockfish 111

Unidentified rockfish YOY 41

Blue rockfish 25

Painted greenling 14

Kelp rockfish 14

Bocaccio YOY 12

Flag rockfish 7

Halfmoon 5

Olive rockfish 5

Copper rockfish 4

Garibaldi 4

Kelp bass 1

Sebastomus sp. 1 

 

TOTAL 836 

Minimum number of species 13 

Total rockfish YOY 523

Total rockfishes 690

Rockfish YOY comprised 62.6% of all fishes surveyed. 

All rockfishes comprised 82.5% of all fishes surveyed. 
A-18

APPENDIIX 3

A-19

APPENDIIX 3

PLATFORM MIDWATERS, cont.

PLATFORM GRACE (Surveyed 1996–2001) PLATFORM GILDA (Surveyed 2000)

Species Number Density Species Number Density

Unidentified rockfish YOY 5,454 79 Widow rockfish 650 

Widow rockfish YOY 2,768 40 Blue rockfish 23 

Squarespot rockfish 1,554 22 Olive rockfish 15 

Blue rockfish 1,029 15 Kelp bass 6 

Widow rockfish 633 9 Kelp rockfish 6 

Bocaccio YOY 396 6 Painted greenling 5 

Blacksmith 313 4 Squarespot rockfish 3 

Bocaccio 142 2 Blacksmith 2 

Painted greenling 86 1 Bocaccio 2 

Sharpnose seaperch 54 <1 Lingcod 1 

Jack mackerel 54 <1 Mola 1 

Flag rockfish 46 <1 Opaleye 1 

Kelp rockfish 35 <1 Pile perch 1 

Olive rockfish 30 <1 Senorita 1 

Pacific mackerel 30 <1 Sharpnose seaperch 1 

Unidentified rockfish 28 <1 

Halfmoon 26 <1 TOTAL 718 

Chilipepper 25 <1 Minimum number of species 15 

Sebastomus sp. 15 <1 Total rockfishes 699 

Brown rockfish 10 <1 All rockfishes comprised 97.4% of all fishes surveyed.

Copper rockfish 10 <1 

Lingcod 7 <1 

Whitespeckled rockfish 5 <1 

Unknown fish 4 <1 

Unknown sculpin 3 <1 

Greenspotted rockfish 3 <1 

Rosy rockfish 2 <1 

Swordspine rockfish 2 <1 

Treefish 2 <1 

Calico rockfish 1 <1 

Cowcod 1 <1 

Kelp greenling 1 <1 

Pink seaperch 1 <1 

Vermilion rockfish 1 <1 

White seaperch 1 <1 

Unidentified seaperch 1 <1 

 

TOTAL 12,773 178 

Minimum number of species 29 

Total rockfish YOY 8,618 125 

Total rockfishes 12,192 173 

Rockfish YOY comprised 67.5% of all fishes surveyed. 

All rockfishes comprised 95.5% of all fishes surveyed. 

PLATFORM MIDWATERS, cont.

PLATFORM GAIL (Surveyed 1996–2001) PLATFORM EDITH (Surveyed 1998)

Species Number Density Species Number Density

Unidentified rockfish YOY 2,371 24 Blacksmith 1,241 265

Blacksmith 241 2 Halfmoon 59 13

Flag rockfish YOY 102 1 Opaleye 37 8

Widow rockfish YOY 93 <1 Sheephead 23 5

Painted greenling 46 <1 Garibaldi 20 4

Bocaccio YOY 28 <1 Sharpnose seaperch 8 1

Unidentified fish 23 <1 Kelp bass 5 1

Pinkrose rockfish 12 <1 Painted greenling 4 1

Widow rockfish 8 <1 

Squarespot rockfish 7 <1 TOTAL 1,397 298

Whitespeckled rockfish 6 <1 Minimum number of species 8 

Bank rockfish 4 <1 No rockfishes observed.

Unidentified rockfish 4 <1 

Greenblotched rockfish 3 <1 

Blue rockfish 2 <1 

Cabezon 2 <1 

Greenspotted rockfish 2 <1 

Olive rockfish 2 <1 

Bocaccio 1 <1 

Chilipepper 1 <1 

Kelp greenling 1 <1 

Pacific hake 1 <1 

Sebastomus sp. 1 <1 

Swordspine rockfish 1 <1 

 

TOTAL 2,962 26 

Minimum number of species 19 

Total rockfish YOY 2,593 25 

Total rockfishes 2,648 25 

Rockfish YOY comprised 87.5% of all fishes surveyed. 

All rockfishes comprised 89.4% of all fishes surveyed. 
A-20

APPENDIIX 3

A-21

APPENDIIX 3

PLATFORM BOTTOMS

PLATFORM IRENE (Surveyed 1996–2001) PLATFORM HIDALGO (Surveyed 1996–2001)

Species Number Density Species Number Density

Halfbanded rockfish 5,393 217 Halfbanded rockfish 9,664 305

Unidentified rockfish YOY 1,411 57 Greenspotted rockfish 587 19

Copper rockfish 1,187 47 Unidentified rockfish YOY 307 10

Vermilion rockfish 799 40 Flag rockfish 256 8

Lingcod 468 19 Lingcod 97 3

Calico rockfish 381 15 Greenblotched rockfish 69 2

Widow rockfish YOY 335 13 Widow rockfish 69 2

Pile perch 115 5 Greenstriped rockfish 60 2

Painted greenling 105 4 Bocaccio 56 2

Pacific sanddab 96 4 Painted greenling 47 1

Brown rockfish 78 3 Vermilion rockfish 43 1

Yellowtail rockfish 30 1 Canary rockfish 39 1

Canary rockfish 28 1 Rosy rockfish 36 1

Blue rockfish 25 1 Widow rockfish YOY 34 1

Rosy rockfish 21 <1 Squarespot rockfish 28 <1

Kelp greenling 20 <1 Sebastomus sp. 26 <1

Rubberlip seaperch 19 <1 Sharpchin rockfish 15 <1

Bocaccio YOY 17 <1 Pygmy rockfish 12 <1

Sebastomus sp. 12 <1 Yelloweye rockfish 12 <1

Olive rockfish 8 <1 Swordspine rockfish 10 <1

Unidentified seaperch 5 <1 Cowcod 8 <1

Gopher rockfish 5 <1 Unidentified rockfish 8 <1

Sharpnose seaperch 4 <1 Starry rockfish 6 <1

Squarespot rockfish 4 <1 Unidentified combfish 6 <1

Widow rockfish 4 <1 Kelp greenling 5 <1

Unidentified fish 4 <1 Bocaccio YOY 4 <1

Greenspotted rockfish 3 <1 Shortspine combfish 2 <1

Unidentified rockfish 3 <1 Bank rockfish 1 <1

Bocaccio 2 <1 Stripetail rockfish 1 <1

Flag rockfish 2 <1 Unidentified poacher 1 <1

Kelp rockfish 2 <1 

Honeycomb rockfish 1 <1 TOTAL 11,509 358

Yelloweye rockfish 1 <1 Minimum number of species 24 

Unidentified ronquil 1 <1 Total rockfish YOY 345 11

Unidentified sanddab 1 <1 Total rockfishes 11, 351 354

Unidentified flatfish 1 <1 Rockfish YOY comprised 3.0% of all fishes surveyed.

 All rockfishes comprised 98.6% of all fishes 

 surveyed.

TOTAL 10,591 427 

Minimum number of species 29 

Total rockfish YOY 1,766 70 

Total rockfishes 9,748 395 

Rockfish YOY comprised 16.7% of all fishes surveyed. 

All rockfishes comprised 92% of all fishes surveyed. 

PLATFORM BOTTOMS, cont.

PLATFORM HARVEST (Surveyed 1997–2000) PLATFORM HERMOSA (Surveyed 1996–2000)

Species Number Density Species Number Density

Stripetail rockfish 250 10 Halfbanded rockfish 6,718 262

Greenstriped rockfish 207 8 Greenspotted rockfish 321 13

Greenspotted rockfish 78 3 Flag rockfish 42 2

Greenblotched rockfish 67 3 Sebastomus sp. 26 1

Sharpchin rockfish 44 2 Lingcod 24 1

Lingcod 35 1 Unidentified rockfish YOY 9 <1

Sebastomus sp. 24 <1 Pinkrose rockfish 7 <1

Flag rockfish 17 <1 Shortspine combfish 7 <1

Unidentified rockfish 12 <1 Cowcod 6 <1

Unidentified combfish 10 <1 Greenstriped rockfish 6 <1

Unidentified rockfish YOY 6 <1 Greenblotched rockfish 5 <1

Chilipepper 5 <1 Shortbelly rockfish 4 <1

Halfbanded rockfish 4 <1 Unidentified rockfish YOY 4 <1

Shortspine combfish 4 <1 Pacific hake 2 <1

Unidentified flatfish 3 <1 Ratfish 2 <1

Cowcod 2 <1 Swordspine rockfish 2 <1

Pinkrose rockfish 2 <1 Unidentified rockfish 2 <1

Unidentified poacher 2 <1 Bocaccio YOY 1 <1

Bank rockfish 1 <1 Canary rockfish 1 <1

Bocaccio 1 <1 Darkblotched rockfish 1 <1

Swordspine rockfish 1 <1 Pink seaperch 1 <1

 Sharpchin rockfish 1 <1

TOTAL 775 27 Starry rockfish 1 <1

Minimum number of species 17 Whitespeckled rockfish 1 <1

Total rockfish YOY 6 <1 Widow rockfish 1 <1

Total rockfishes 721 26 Unidentified combfish 1 <1

Rockfish YOY comprised <1% of all fishes surveyed. Unidentified fish 1 <1

All rockfishes comprised 93.0% of all fishes surveyed. Unidentified flatfish 1 <1

 Unidentified poacher 1 <1

 

 TOTAL 7,195 279

 Minimum number of species 23 

 Total rockfish YOY 14 <1

 Total rockfishes 7,159 278

 Rockfish YOY comprised <1% of all fishes surveyed.

 All rockfishes comprised 99.5% of all fishes 

 surveyed.
A-22

APPENDIIX 3

A-23

APPENDIIX 3

PLATFORM BOTTOMS, cont.

PLATFORM HOLLY (Surveyed 1996–1999, 2001) PLATFORM GRACE (Surveyed 1996, 1997, 

 1999–2001)

Species Number Density Species Number Density

Widow rockfish YOY 1,028 49 Halfbanded rockfish 11,078 408

Calico rockfish 726 35 Widow rockfish 413 15

Vermilion rockfish 444 21 Squarespot rockfish 220 8

Sharpnose seaperch 407 19 Vermilion rockfish 205 8

Halfbanded rockfish 405 19 Bocaccio YOY 203 7

Copper rockfish 285 13 Bocaccio 183 7

Squarespot rockfish 221 10 Shiner perch 130 5

Blackeye goby 67 3 Flag rockfish 103 4

Unidentified seaperch 66 3 Unidentified sanddab 79 3

Unidentified rockfish YOY 54 3 Greenspotted rockfish 66 2

Pink seaperch 53 3 Lingcod 41 2

Painted greenling 51 2 Painted greenling 29 1

Rosy rockfish 43 2 Unidentified rockfish YOY 28 1

Brown rockfish 38 2 Chilipepper 26 <1

Pile perch 37 2 Sebastomus sp. 24 <1

Lingcod 36 2 Rosy rockfish 21 <1

Widow rockfish 29 1 Pink seaperch 19 <1

Flag rockfish 24 1 Unidentified flatfish 12 <1

Sebastomus sp. 24 1 Blue rockfish 9 <1

Unidentified flatfish 20 <1 Kelp greenling 9 <1

Honeycomb rockfish 19 <1 Copper rockfish 8 <1

Canary rockfish 18 <1 Unidentified rockfish 8 <1

Unidentified rockfish 13 <1 Canary rockfish 7 <1

Blue rockfish 12 <1 Unidentified fish 6 <1

Unidentified ronquil 10 <1 Treefish 5 <1

Rubberlip seaperch 9 <1 Greenblotched rockfish 4 <1

Treefish 9 <1 Unidentified combfish 4 <1

Kelp rockfish 8 <1 Whitespeckled rockfish 3 <1

Olive rockfish 8 <1 Widow rockfish 3 <1

Gopher rockfish 7 <1 Shortspine combfish 3 <1

Kelp greenling 5 <1 Yellowtail rockfish 2 <1

Unidentified fish 4 <1 Pink rockfish 1 <1

California scorpionfish 3 <1 Rathbunella sp. 1 <1

Bocaccio YOY 2 <1 Yelloweye rockfish 1 <1

Rathbunella sp. 2 <1 Unidentified sculpin 1 <1

Yellowtail rockfish 2 <1 

Unidentified combfish 2 <1 TOTAL 12,955 471

Cowcod 1 <1 Minimum number of species 28 

Greenspotted rockfish 1 <1 Total rockfish YOY 231 8

Shortspine combfish 1 <1 Total rockfishes 12,621 460

Shortspine thornyhead 1 <1 Rockfish YOY comprised 1.8% of all fishes surveyed.

 All rockfishes comprised 97.4% of all fishes surveyed.

TOTAL 4,195 191 

Minimum number of species 33 

Total rockfish YOY 1,084 52 

Total rockfishes 3,421 157 Rockfish YOY comprised 25.8% of all fishes surveyed.

 All rockfishes comprised 81.5% of all fishes surveyed.

 

PLATFORM BOTTOMS, cont.

PLATFORM GAIL (Surveyed 1996, 1997, 1999–2001) PLATFORM EDITH (Surveyed 1998)

Species Number Density Species Number Density

Greenblotched rockfish 369 12 California scorpionfish 274 63

Bocaccio 328 11 Sharpnose seaperch 71 16

Greenspotted rockfish 278 9 Blacksmith 35 8

Stripetail rockfish 200 7 Blackeye goby 22 5

Pinkrose rockfish 168 6 Treefish 9 2

Sebastomus sp. 63 2 Unidentified seaperch 8 2

Greenstriped rockfish 61 2 Painted greenling 6 1

Cowcod 34 1 Unidentified rockfish YOY 5 1

Mexican rockfish 22 <1 Pile perch 3 <1

Lingcod 17 <1 Cabezon 3 <1

Unidentified rockfish 14 <1 Unidentified fish 3 <1

Flag rockfish 11 <1 Honeycomb rockfish 2 <1

Chilipepper 7 <1 Squarespot rockfish 1 <1

Unidentified rockfish YOY 5 <1 Sebastomus sp. 1 <1

Unidentified poachers 4 <1 California sheephead 1 <1

Swordspine rockfish 3 <1 Unidentified rockfish 1 <1

Dover sole 2 <1 

Unidentified fish 2 <1 TOTAL 445 98

Unidentified flatfish 2 <1 Minimum number of species 12 

Bank rockfish 1 <1 Total rockfish YOY 5 <1

Bocaccio YOY 1 <1 Total rockfishes 19 

Darkblotched rockfish 1 <1 Rockfish YOY comprised 1.1% of all fishes 

surveyed.

Northern anchovy 1 <1 All rockfishes comprised 1% of all fishes surveyed.

Painted greenling 1 <1 

Pink rockfish 1 <1 

Redbanded rockfish 1 <1 

Sharpchin rockfish 1 <1 

Widow rockfish 1 <1 

Unidentified combfish 1 <1 

 

TOTAL 1,600 50 

Minimum number of species 23 

Total rockfish YOY 5 <1 

Total rockfishes 1,570 50 

Rockfish YOY comprised <1% of all fishes surveyed. 

All rockfishes comprised 98.2% of all fishes surveyed. 
A-24

APPENDIIX 3

A-25

APPENDIIX 3

PLATFORM SHELL MOUNDS

PLATFORM IRENE (SURVEYED 1996–2001) PLATFORM HIDALGO (SURVEYED 1996–2001)

Species Number Density Species Number Density

Halfbanded rockfish 965 45 Halfbanded rockfish 3,496 124

Lingcod 404 19 Lingcod 127 4

Copper rockfish 215 10 Painted greenling 35 1

Pacific sanddab 92 4 Greenspotted rockfish 28 <1

Vermilion rockfish 76 4 Greenstriped rockfish 24 <1

Painted greenling 72 3 Unidentified rockfish YOY 21 <1

Calico rockfish 32 2 Rosy rockfish 20 <1

Pile perch 18 <1 Pacific sanddab 17 <1

Rosy rockfish 9 <1 Swordspine rockfish 17 <1

Kelp greenling 8 <1 Unidentified combfish 8 <1

Unidentified rockfish YOY 8 <1 Unidentified sanddab 7 <1

Olive rockfish 5 <1 Cowcod 4 <1

Unidentified fish 5 <1 Flag rockfish 4 <1

Canary rockfish 3 <1 Pink seaperch 4 <1

Unidentified flatfish 3 <1 Shortspine combfish 4 <1

Unidentified sanddab 3 <1 Unidentified poacher 4 <1

Bocaccio YOY 2 <1 Canary rockfish 2 <1

Brown rockfish 2 <1 Unidentified fish 2 <1

Sebastomus sp. 2 <1 Bank rockfish 1 <1

Widow rockfish 2 <1 Longspine combfish 1 <1

Wolf-eel 2 <1 Pygmy rockfish 1 <1

Yellowtail rockfish 2 <1 Ratfish 1 <1

Unidentified ronquil 2 <1 Rathbunella sp. 1 <1

Flag rockfish 1 <1 Sebastomus sp. 1 <1

Pink seaperch 1 <1 Sharpchin rockfish 1 <1

Unidentified rockfish 1 <1 Starry rockfish 1 <1

Unidentified sculpin 1 <1 Vermilion rockfish 1 <1

 Unidentified rockfish 1 <1

TOTAL 1,936 87 Unidentified ronquil 1 <1

Minimum number of species 23 

Total rockfish YOY 8 <1 TOTAL 3,835 129

Total rockfishes 1,341 61 Minimum number of species 22 

Rockfish YOY comprised <1% of all fishes surveyed. Total rockfish YOY 21 <1

All rockfishes comprised 69.3% of all fishes surveyed. Total rockfishes 3,623 124

 Rockfish YOY comprised <1% of all fishes surveyed.

 All rockfishes comprised 94.5% of all fishes 

 surveyed.

PLATFORM SHELL MOUNDS, cont.

PLATFORM HARVEST (Surveyed 1997–2000) PLATFORM HERMOSA (Surveyed 1997–2000)

Species Number Density Species Number Density

Stripetail rockfish 373 14 Halfbanded rockfish 3,572 188

Greenstriped rockfish 136 5 Shortbelly rockfish 114 6

Sharpchin rockfish 91 3 Stripetail rockfish 64 3

Greenspotted rockfish 41 2 Shortspine combfish 38 2

Unidentified poacher 18 <1 Greenspotted rockfish 27 1

Sebastomus sp. 17 <1 Greenstriped rockfish 14 <1

Lingcod 16 <1 Unidentified sanddab 11 <1

Greenblotched rockfish 9 <1 Lingcod 9 <1

Unidentified rockfish 8 <1 Unidentified combfish 9 <1

Unidentified flatfish 7 <1 Flag rockfish 6 <1

Shortspine combfish 7 <1 Sebastomus sp. 6 <1

Unidentified combfish 6 <1 Cowcod 4 <1

Pinkrose rockfish 5 <1 Unidentified poacher 3 <1

Unidentified rockfish YOY 5 <1 Greenblotched rockfish 3 <1

Halfbanded rockfish 4 <1 Unidentified fish 3 <1

Unidentified fish 3 <1 Longspine combfish 2 <1

Chilipepper 2 <1 Pink seaperch 2 <1

Bank rockfish 1 <1 Rosy rockfish 2 <1

Cowcod 1 <1 Unidentified rockfish YOY 2 <1

Flag rockfish 1 <1 Blackeye goby 1 <1

Pacific hake 1 <1 Ratfish 1 <1

Ratfish 1 <1 Widow rockfish 1 <1

Rathbunella sp. 1 <1 Unidentified rockfish 1 <1

Swordspine rockfish 1 <1 

Unidentified sanddab 1 <1 TOTAL 3,895 200

 Minimum number of species 17 

TOTAL 756 24 Total rockfish YOY 2 <1

Minimum number of species 18 Total rockfishes 3,814 

Total rockfish YOY 5 <1 Rockfish YOY comprised <1% of all fishes surveyed.

Total rockfishes 695 24 All rockfishes comprised 97.9% of all fishes 

surveyed.

Rockfish YOY comprised <1% of all fishes surveyed. 

All rockfishes comprised 91.9% of all fishes surveyed. 
A-26

APPENDIIX 3

A-27

APPENDIIX 3

PLATFORM SHELL MOUNDS, cont.

PLATFORM HOLLY (Surveyed 1997, 1998, 2001) PLATFORM C (Surveyed 2000)

Species Number Density Species Number Density

Pacific sardine 200 25 Vermilion rockfish 153 74

Calico rockfish 129 16 Halfbanded rockfish 59 29

Vermilion rockfish 64 8 Calico rockfish 33 16

Copper rockfish 44 5 Olive rockfish 19 9

Halfbanded rockfish 35 4 Blackeye goby 16 8

Blackeye goby 31 4 Copper rockfish 15 7

Squarespot rockfish 21 3 Painted greenling 10 5

Pink seaperch 18 2 Kelp rockfish 9 4

Lingcod 14 2 Lingcod 8 4

Honeycomb rockfish 13 2 Brown rockfish 1 <1

Painted greenling 13 2 Canary rockfish 1 <1

Flag rockfish 11 1 Widow rockfish 1 <1

Rosy rockfish 9 1 Yellowtail rockfish 1 <1

Canary rockfish 8 <1 

Brown rockfish 6 <1 TOTAL 326 156

Kelp greenling 6 <1 Minimum number of species 13 

Pile perch 6 <1 Total rockfishes 292 139

Unidentified fish 6 <1 All rockfishes comprised 89.5% of all fishes 

 surveyed.

Rathbunella sp. 5 <1 

Sebastomus sp. 5 <1 

Unidentified flatfish 4 <1 

Unidentified ronquil 4 <1 

Olive rockfish 3 <1 

Pacific hake 3 <1 

Unidentified combfish 3 <1 

Unidentified rockfish 2 <1 

California halibut 1 <1 

California scorpionfish 1 <1 

Sharpnose seaperch 1 <1 

Treefish 1 <1 

Widow rockfish 1 <1 

Sebastomus sp. 1 <1 

Unidentified seaperch 1 <1 

Unidentified rockfish YOY 1 <1 

 

TOTAL 670 75 

Minimum number of species 26 

Total rockfish YOY 1 <1 

Total rockfishes 354 40 

Including the one-time observation of Pacific sardine, YOY rockfishes comprised <1%, and all rockfishes comprised 

52.8% of all fishes surveyed. 

Excluding sardines, YOY rockfishes comprised <1%, and all rockfish comprised 75.3% of all fishes.

PLATFORM SHELL MOUNDS, cont.

PLATFORM GRACE (Surveyed 1997–2001) PLATFORM GAIL (Surveyed 1997, 1999–2001)

Species Number Density Species Number Density

Halfbanded rockfish 4,154 144 Pacific hake 470 15

Shiner perch 1,031 36 Stripetail rockfish 242 8

Pink seaperch 171 6 Northern anchovy 158 5

Unidentified sanddab 148 5 Pinkrose rockfish 112 4

Bocaccio YOY 91 3 Greenblotched rockfish 65 2

Lingcod 88 3 Greenstriped rockfish 60 2

Unidentified rockfish YOY 80 3 Unidentified poacher 46 2

Greenspotted rockfish 38 1 Unidentified combfish 29 <1

Flag rockfish 35 1 Swordspine rockfish 25 <1

Vermilion rockfish 34 1 Shortbelly rockfish 23 <1

Shortspine combfish 27 <1 Sharpchin rockfish 18 <1

Unidentified combfish 26 <1 Darkblotched rockfish 12 <1

Hornyhead turbot 15 <1 Dover sole 11 <1

Painted greenling 10 <1 Unidentified fish 11 <1

Blue rockfish 8 <1 Sebastomus sp. 9 <1

Sebastomus sp. 5 <1 Unidentified rockfish 9 <1

Bocaccio 4 <1 Pacific sanddab 8 <1

Canary rockfish 4 <1 Unidentified rockfish YOY 8 <1

Swordspine rockfish 4 <1 Unidentified sculpin 8 <1

California scorpionfish 2 <1 Greenspotted rockfish 8 <1

Copper rockfish 2 <1 Jack mackerel 7 <1

Kelp greenling 2 <1 Blackgill rockfish 5 <1

Rathbunella sp. 2 <1 Chilipepper 4 <1

Rosy rockfish 2 <1 Unidentified flatfish 4 <1

Unidentified flatfish 2 <1 Cowcod 3 <1

Greenstriped rockfish 1 <1 Flag rockfish 3 <1

Hornyhead turbot 1 <1 Mexican rockfish 3 <1

Squarespot rockfish 1 <1 Pacific electric ray 2 <1

Treefish 1 <1 Unidentified ronquil 2 <1

Unidentified fish 1 <1 Bocaccio 1 <1

Unidentified rockfish 1 <1 California smoothtongue 1 <1

Unidentified seaperch 1 <1 California tonguefish 1 <1

 Halfbanded rockfish 1 <1

TOTAL 5,992 203 Redbanded rockfish 1 <1

Minimum number of species 25 Rex sole 1 <1

Total rockfish YOY 171 6 

Total rockfishes 4,464 153 TOTAL 1,371 38

Rockfish YOY comprised <1% of all fishes surveyed. Minimum number of species 30 

All rockfishes comprised 74.5% of all fishes surveyed. Total rockfish YOY 8 <1

 Total rockfishes 603 16

 Rockfish YOY comprised <1% of all fishes surveyed.

 All rockfishes comprised 44.0% of all fishes surveyed.
A-28

APPENDIIX 3

A-29

PLATFORM SHELL MOUNDS, cont.

PLATFORM EDITH (Surveyed 1998) 

Species Number Density

California scorpionfish 280 67

Blackeye goby 81 19

Unidentified fish 3 <1

Unidentified rockfish YOY 3 <1

Unidentified seaperch 3 <1

Calico rockfish 2 <1

Sharpnose seaperch 2 <1

Painted greenling 1 <1

Pile seaperch 1 <1

Unidentified flatfish 1 <1

TOTAL 377 0.86

Minimum number of species 8 

Total rockfish YOY 3 <1

Total rockfishes 5 <1

Rockfish YOY comprised <1% of all fishes surveyed.

All rockfishes comprised <1% of all fishes surveyed.

 

APPENDIX 4

Densities, at the top 20 sites, of some of the most abundant species in our deepwater surveys. Platforms are listed in 

blue, natural outcrops in red.

Species Site Year Habitat Type Density(Fish per 100 m2)

Lingcod (adult) Hidalgo 1996 Bottom 3.2

 Irene 1997 Bottom 1.7

 Irene 1997 Shell Mound 1.5

 Hermosa 1996 Bottom 1.0

 Footprint 2001 Natural 1.0

 Hermosa 1997 Bottom 0.9

 Reef “A” 1997 Natural 0.8

 Reef “A” 1998 Natural 0.7

 Hermosa 1999 Bottom 0.7

 Gail 2001 Bottom 0.7

 Santa Monica Bay 2001 Natural 0.7

 Santa Cruz I. 2000 Natural 0.6

 Santa Monica Bay 2001 Natural 0.5

 Hermosa 2000 Bottom 0.5

 Gail 1996 Bottom 0.5

 Gail 1997 Bottom 0.5

 Gail 1999 Bottom 0.5

 GAIL 2000 Bottom 0.5

 Irene 1998 Bottom 0.5

 Irene 2000 Bottom 0.5

 Irene 2001 Bottom 0.5

Lingcod (juvenile) Irene 1996 Bottom 18.8

 Holly 1999 Bottom 6.1

 Grace 2000 Shell Mound 5.4

 Grace 2001 Platform pipe 4.6

 14 Mile Bank 2001 Natural 4.5

 Grace 2000 Bottom 3.8

 Hidalgo 1999 Shell mound 3.6

 Platform “C” 2000 Shell mound 3.4

 Grace 2001 Shell mound 3.2

 Irene 2001 Bottom 2.7

 Hidalgo 1997 Bottom 2.7

 Grace 1999 Shell Mound 2.3

 Harvest 2000 Bottom 2.2

 Grace 2001 Bottom 2.2

 Irene 1999 Bottom 2.2

 Hidalgo 2000 Bottom 2.1

 Harvest 1999 Bottom 1.9

 More Mesa 1995 Natural 1.9

 Irene 1997 Shell Mound 1.9

 12 Mile Reef 2000 Natural 1.8

Lingcod YOY Irene 1998 Shell Mound 31.5

 Irene 2001 Shell Mound 29.2

 Irene 2001 Bottom 24.1

 Irene 1998 Bottom 19.6

 Irene 1996 Bottom 17.9

 Irene 2000 Shell Mound 12.0

 Irene 1997 Shell Mound 10.9

 Irene 2000 Bottom 10.6

An invertebrate tossed salad at the bottom of Platform Grace.

DONNA SCHROEDER
A-30

APPENDIIX 4

A-31

APPENDIIX 4

Species Site Year Habitat Type Density(Fish per 100 m

2

)

Lingcod YOY (cont.) Irene 1999 Shell Mound 9.7

 Irene 1999 Bottom 7.5

 Hidalgo 1999 Shell Mound 4.6

 Hidalgo 2000 Shell Mound 4.3

 Hidalgo 2000 Bottom 3.0

 Irene 1997 Bottom 2.9

 Hidalgo 2001 Shell Mound 2.6

 Hidalgo 1998 Shell Mound 1.9

 Hidalgo 1997 Shell Mound 1.8

 Grace 1999 Shell Mound 1.2

 Hidalgo 1998 Bottom 1.1

 Hidalgo 1999 Bottom 1.1

Painted greenling Holly 1998 Midwater 18.0

 Harvest 1999 Midwater 9.9

 Harvest 1997 Midwater 9.9

 Holly 2001 Midwater 8.2

 Hermosa 1997 Midwater 8.1

 Irene 1997 Bottom 8.0

 Hermosa 1998 Midwater 6.9

 Hermosa 1999 Midwater 5.5

 Houchin 2000 Midwater 5.3

 Irene 1997 Shell Mound 5.3

 Irene 2000 Shell Mound 5.1

 Irene 1996 Bottom 4.8

 Harvest 1999 Midwater 4.7

 Holly 1998 Shell Mound 4.6

 Irene 2000 Bottom 4.6

 Irene 2000 Midwater 4.5

 Platform “C” 2000 Shell Mound 4.4

 Hermosa 2000 Midwater 4.4

 Irene 2001 Bottom 4.4

 Hidalgo 2000 Midwater 4.2

Greenspotted rockfish Hermosa 1996 Bottom 30.3

 Hidalgo 2000 Bottom 21.8

 Gail 1996 Bottom 21.3

 Hidalgo 1996 Bottom 20.6

 Hidalgo 1999 Bottom 19.9

 Hidalgo 1998 Bottom 19.1

 Hidalgo 1997 Bottom 17.6

 Hidalgo 2001 Bottom 12.1

 Gail 1997 Bottom 10.8

 Hermosa 1997 Bottom 10.6

 North Reef 1997 Natural 9.8

 Gail 2000 Bottom 9.3

 Hermosa 1998 Bottom 9.1

 Hermosa 2000 Bottom 5.8

 Reef “A” 1997 Natural 5.0

 North Reef 1998 Natural 5.0

 Reef “C” 1999 Natural 4.9

Species Site Year Habitat Type Density(Fish per 100 m

2

)

Greenspotted rockfish Reef “A” 2000 Natural 4.8

(cont.) Hermosa 1999 Bottom 4.3

 Grace 1996 Bottom 4.0

Copper rockfish Irene 2000 Bottom 88.5

 Irene 1996 Bottom 71.6

 Irene 1997 Bottom 53.6

 Irene 2001 Bottom 40.8

 Irene 2000 Shell Mound 27.1

 Holly 1997 Bottom 21.8

 Holly 1999 Bottom 21.5

 Irene 1999 Bottom 21.5

 Holly 1998 Shell Mound 12.0

 Holly 1996 Bottom 11.4

 Irene 2001 Shell Mound 10.4

 Irene 1998 Bottom 10.4

 Holly 1997 Shell Mound 9.3

 Holly 2001 Bottom 8.4

 Platform “C” 2000 Shell Mound 7.3

 Irene 1997 Shell Mound 5.2

 Irene 1999 Shell Mound 4.5

 Holly 1998 Bottom 4.4

 Irene 2001 Midwater 3.9

 Irene 2000 Midwater 3.7

Swordspine rockfish 14 Mile Bank 1996 Natural 94.4

 14 Mile Bank 1996 Natural 47.4

 14 Mile Bank 2001 Natural 45.8

 Footprint 2000 Natural 41.0

 Footprint 2000 Natural 39.6

 Footprint 1999 Natural 29.7

 Osborn Bank 2000 Natural 27.5

 Footprint 2001 Natural 24.9

 Catalina I. 1996 Natural 22.4

 Santa Monica Bay 2001 Natural 21.9

 Tanner Bank 1997 Natural 20.1

 Footprint 2000 Natural 20.1

 Santa Barbara I. 2000 Natural 18.3

 Footprint 2001 Natural 15.3

 Footprint 2000 Natural 14.2

 Cortes Bank 1997 Natural 12.8

 Santa Monica Bay 1998 Natural 10.6

 Footprint 2001 Natural 9.9

 Footprint 2000 Natural 8.3

 Footprint 1999 Natural 8.2

Greenstriped rockfish Harvest 2000 Bottom 14.7

 Harvest 1999 Bottom 9.2

 Gail 2000 Bottom 7.5

 Harvest 1997 Shell Mound 7.1

 Harvest 1997 Shell Mound 6.1

 Harvest 2000 Shell Mound 5.9
A-32

APPENDIIX 4

A-33

APPENDIIX 4

Species Site Year Habitat Type Density(Fish per 100 m

2

)

Greenstriped rockfish Harvest 1998 Bottom 5.2

(cont.) Harvest 1999 Shell Mound 4.3

 Harvest 1997 Bottom 3.6

 Harvest 1998 Shell Mound 3.5

 Hidalgo 1998 Bottom 3.4

 Hidalgo 2000 Bottom 3.4

 Reef “A” 2000 Natural 3.3

 Gail 1997 Shell Mound 2.6

 Reef “A” 1997 Natural 2.5

 Gail 1999 Shell Mound 2.4

 Hidalgo 2001 Bottom 2.3

 Gail 2000 Shell Mound 2.2

 Santa Rosa Passage 1995 Natural 2.2

 Hidalgo 1998 Shell Mound 2.1

Widow rockfish (YOY) Irene 1998 Midwater 344.0

 Irene 1996 Midwater 253.3

 Holly 1999 Bottom 252.9

 Harvest 1999 Midwater 188.9

 Grace 2000 Midwater 175.7

 Irene 1997 Midwater 173.6

 San Nicholas I. 1996 Natural 173.5

 Catalina I. 1996 Natural 116.8

 Irene 1998 Bottom 79.1

 Grace 2001 Midwater 73.8

 San Nicolas I. 1996 Natural 68.1

 Grace 1997 Bottom 66.3

 Cortes Bank 1997 Natural 66.0

 Santa Cruz I. 2000 Natural 65.4

 North Reef 1999 Natural 63.6

 Hidalgo 1998 Midwater 52.9

 Footprint 1995 Natural 45.9

 Hermosa 2000 Midwater 44.4

 Footprint 2001 Natural 40.3

 Grace 1999 Midwater 39.6

Squarespot rockfish Santa Cruz I. 2000 Natural 282.5

 Santa Barbara I. 2000 Natural 263.0

 Santa Monica Bay 1998 Natural 196.4

 Harvest 1999 Midwater 180.0

 Cortes Bank 1997 Natural 149.6

 Grace 2001 Midwater 130.6

 San Miguel I. 1995 Natural 122.1

 Footprint 1998 Natural 94.6

 San Nicolas I. 1996 Natural 93.9

 Anacapa Passage 1999 Natural 88.8

 Santa Monica Bay 1998 Natural 85.0

 Hidden Reef 1999 Natural 72.6

 San Nicolas I. 1996 Natural 69.7

 Guano Bank 1995 Natural 69.6

 Footprint 2000 Natural 61.8

Species Site Year Habitat Type Density(Fish per 100 m

2

)

Squarespot rockfish Osborn Bank 2000 Natural 54.9

(cont.) Osborn Bank 2000 Natural 51.9

 Anacapa Passage 1995 Natural 50.5

 Santa Monica Bay 2001 Natural 44.3

 Santa Rosa I. 1995 Natural 43.4

Vermilion rockfish Platform “C” 2000 Shell Mound 74.5

 Holly 2001 Bottom 58.1

 Irene 2000 Bottom 55.2

 Irene 1996 Bottom 47.8

 Irene 1997 Bottom 32.8

 Grace 2001 Platform pipe 30.8

 Irene 1999 Bottom 30.4

 Anacapa Passage 1995 Natural 30.1

 Grace 2001 Bottom 29.9

 Holly 1999 Bottom 23.8

 Holly 1996 Bottom 22.0

 Irene 2001 Bottom 14.0

 Irene 1998 Bottom 12.5

 Holly 2001 Shell Mound 11.9

 Irene 2000 Shell Mound 10.6

 Grace 2001 Bottom 8.8

 Holly 1998 Shell Mound 8.3

 Irene 2001 Shell Mound 6.1

 Santa Cruz I. 2000 Natural 5.2

 Holly 1997 Bottom 4.5

Bocaccio (adult) Gail 1997 Bottom 18.2

 Gail 1999 Bottom 11.0

 Gail 1996 Bottom 10.8

 Gail 2000 Bottom 6.2

 Gail 2001 Bottom 3.5

 Hidalgo 2001 Bottom 3.0

 Hidalgo 1996 Bottom 2.7

 Reef “A” 1997 Natural 1.9

 Reef “D” 1999 Natural 1.6

 Hidalgo 1997 Bottom 1.3

 Santa Rosa Passage 1995 Natural 1.2

 Footprint 1995 Natural 1.1

 Hidalgo 1998 Bottom 0.9

 Footprint 2001 Natural 0.9

 Footprint 2001 Natural 0.9

 Footprint 2000 Natural 0.8

 Footprint 2000 Natural 0.7

 Catalina I. 1996 Natural 0.6

 Footprint 1999 Natural 0.6

 San Nicolas I. 1996 Natural 0.6

Bocaccio (juvenile) Grace 2000 Bottom 39.6

 Grace 2000 Midwater 13.0

 Santa Cruz I. 2000 Natural 5.6

 14 Mile Bank 2001 Natural 5.1
A-34

APPENDIIX 4

A-35

APPENDIIX 4

Species Site Year Habitat Type Density(Fish per 100 m

2

)

Bocaccio (juvenile) Santa Barbara I. 2000 Natural 2.5

(cont.) Santa Monica Bay 2001 Natural 2.4

 Gail 2001 Bottom 2.3

 Osborn Bank 2000 Natural 2.3

 12 Mile Reef 2000 Natural 2.0

 Gail 2000 Bottom 1.8

 Footprint 2000 Natural 1.2

 Grace 2001 Platform pipe 0.9

 Reef“A” 1997 Natural 0.9

 Footprint 2000 Natural 0.8

 Hidalgo 2000 Bottom 0.8

 Gail 1997 Bottom 0.7

 Footprint 2000 Natural 0.6

 Grace 2000 Shell Mound 0.6

 Hidalgo 1996 Bottom 0.6

 Hidalgo 2001 Bottom 0.6

Bocaccio (YOY) Irene 1999 Midwater 166.4

 Irene 1996 Midwater 91.8

 Grace 1999 Bottom 44.9

 Grace 1999 Midwater 24.1

 Irene 1997 Midwater 17.2

 Grace 1999 Shell Mound 15.9

 Hidalgo 1996 Midwater 5.6

 Harvest 1999 Midwater 4.0

 Grace 2001 Midwater 3.0

 Hidden Reef 1999 Natural 2.3

 Irene 1999 Bottom 2.2

 Grace 2001 Midwater 1.5

 Harvest 1999 Midwater 1.3

 Santa Barbara I. 1996 Natural 1.3

 Irene 1997 Bottom 1.2

 Harvest 1997 Midwater 1.1

 Grace 2000 Midwater 1.0

 Hidalgo 1997 Midwater 0.9

 Santa Monica Bay 2001 Natural 0.9

 Hidalgo 2000 Bottom 0.8

Canary rockfish Irene 2001 Bottom 5.5

 Holly 2001 Bottom 3.4

 Hidalgo 1999 Bottom 1.9

 Holly 2001 Shell Mound 1.7

 Hidalgo 1998 Bottom 1.7

 North Reef 1999 Natural 1.7

 Reef “D” 1999 Natural 1.6

 Hidalgo 1996 Bottom 1.3

 Reef “A” 1999 Natural 1.2

 Irene 1997 Bottom 1.2

 Reef “B” 1997 Natural 1.1

 Hidalgo 1997 Bottom 0.9

 Hidalgo 2001 Bottom 0.9

Species Site Year Habitat Type Density(Fish per 100 m

2

)

 Grace 2000 Bottom 0.9

 Holly 1996 Bottom 0.8

 North Reef 2000 Natural 0.7

 Reef “C” 1998 Natural 0.7

 Irene 2001 Shell Mound 0.7

 Reef “A” 1998 Natural 0.5

 Grace 1998 Shell Mound 0.5

Greenblotched rockfish Gail 1997 Bottom 17.7

 Gail 1999 Bottom 13.7

 Gail 2001 Bottom 11.3

 Hidalgo 2001 Bottom 10.6

 Gail 1996 Bottom 9.7

 Gail 2000 Bottom 9.2

 Gail 1997 Shell Mound 5.9

 Harvest 1999 Bottom 4.6

 Harvest 1998 Bottom 3.8

 Gail 1999 Shell Mound 3.3

 Harvest 1997 Bottom 1.6

 San Miguel I. 1995 Natural 1.4

 Hidalgo 1999 Bottom 1.3

 North Reef 1997 Natural 1.0

 Footprint 2001 Natural 1.0

 Reef “A” 1999 Natural 0.9

 Reef “B” 1997 Natural 0.8

 Hidalgo 2000 Bottom 0.8

 North Reef 2001 Natural 0.7

 Gail 2001 Shell Mound 0.7

Flag rockfish Hidalgo 1997 Bottom 15.5

 Hidalgo 1996 Bottom 11.0

 Hidalgo 1999 Bottom 7.2

 Grace 1996 Bottom 6.6

 Grace 2001 Bottom 5.7

 Hidalgo 1998 Bottom 5.5

 Hidalgo 2000 Bottom 5.1

 Grace 2000 Bottom 4.4

 Hidalgo 2001 Bottom 3.8

 Holly 2001 Bottom 3.1

 Grace 2001 Bottom 3.1

 Santa Barbara Point 1995 Natural 3.0

 Hermosa 1996 Bottom 2.7

 Grace 1999 Midwater 2.6

 Gail 1999 Midwater 2.5

 Hermosa 2000 Bottom 2.2

 Grace 2001 Shell Mound 2.2

 Santa Rosa Passage 1995 Natural 2.0

 Holly 1998 Shell Mound 1.8

 Holly 2001 Shell Mound 1.7
; tk'

A-36

APPENDIIX 4

A-37

APPENDIIX 4

Species Site Year Habitat Type Density(Fish per 100 m2)

Halfbanded rockfish Hidalgo 2000 Bottom 907.1

 Grace 1997 Bottom 800.5

 Anacapa I. 1999 Natural 703.1

 Irene 1999 Bottom 621.2

 Irene 1998 Bottom 595.9

 Hidalgo 2000 Shell Mound 461.0

 Grace 1999 Shell Mound 415.1

 Hermosa 2000 Shell Mound 406.9

 Grace 2000 Bottom 405.2

 Hermosa 2000 Bottom 398.1

 Grace 1996 Bottom 395.1

 Hermosa 1997 Bottom 381.4

 Grace 1999 Bottom 344.2

 Hidalgo 2001 Bottom 318.4

 Hermosa 1999 Bottom 313.2

 E. End Anacapa I. 1995 Natural 284.9

 Hidalgo 1999 Bottom 275.8

 Grace 2001 Bottom 266.4

 Grace 2001 Shell Mound 259.1

 Grace 2001 Bottom 237.7

Pygmy rockfish Hidden Reef 1999 Natural 263.7

 San Nicolas I. 1996 Natural 236.9

 Footprint 2001 Natural 125.7

 Cortes Bank 1997 Natural 119.7

 North Reef 2000 Natural 93.8

 Santa Monica Bay 1998 Natural 93.7

 San Miguel I. 1995 Natural 87.3

 Santa Monica Bay 2001 Natural 84.1

 Cortes Bank 1997 Natural 76.7

 Footprint 2000 Natural 72.2

 Santa Cruz I. 2000 Natural 71.9

 Osborn Bank 2000 Natural 71.2

 San Nicolas I. 1996 Natural 64.6

 14 Mile Bank 2001 Natural 64.5

 San Nicolas I. 1996 Natural 64.2

 Santa Rosa I. 1995 Natural 60.6

 Footprint 2000 Natural 54.6

 Reef “D” 1999 Natural 47.0

 Footprint 1999 Natural 42.3

 Santa Monica Bay 2001 Natural 38.3

Pink seaperch Santa Monica Bay 1998 Natural 304.5

 Grace 1998 Shell Mound 39.2

 Holly 1998 Shell Mound 11.1

 Holly 1999 Bottom 9.1

 Catalina I. 1996 Natural 4.0

 Grace 1997 Shell Mound 2.9

 Grace 1997 Bottom 2.7

 Holly 1996 Bottom 1.8

Species Site Year Habitat Type Density(Fish per 100 m2)

Pink seaperch Reef “D” 1999 Natural 1.7

(cont. Santa Monica Bay 1997 Natural 1.3

 Holly 1997 Bottom 1.3

 Catalina I. 1996 Natural 1.2

 Holly 1997 Shell Mound 1.2

 Santa Monica Bay 1997 Natural 1.2

 Santa Rosa I. 1995 Natural 1.2

 Grace 2000 Bottom 1.1

 Grace 2001 Platform pipe 1.0

 Reef“A” 1997 Natural 0.9

 Santa Cruz I. 1996 Natural 0.8

 North Reef 1998 Natural 0.8

Yellowtail rockfish Reef “B” 1995 Natural 3.9

(adult) San Miguel I. 1995 Natural 3.5

 North Reef 1996 Natural 2.8

 North Reef 1995 Natural 2.1

 Santa Rosa I. 1995 Natural 2.1

 San Miguel I. 1995 Natural 1.9

 San Miguel I. 1995 Natural 1.7

 Reef “D” 1999 Natural 1.6

 North Reef 2000 Natural 1.5

 Reef “A” 2000 Natural 1.0

 San Miguel I. 1995 Natural 0.7

 Reef “A” 1998 Natural 0.7

 Reef “B” 1997 Natural 0.5

 North Reef 1999 Natural 0.5

 Santa Rosa I. 1995 Natural 0.4

 Reef “A” 1997 Natural 0.3

 North Reef 1997 Natural 0.3

 Santa Rosa I. 1995 Natural 0.2

 North Reef 1998 Natural 0.2

Young-of-the-year rockfish in the platform midwater.

LOVELAB UC, SANTA BARBARA