MMS ENVIRONMENTAL STUDIES PROGRAM: ONGOING STUDIES
MMS OCS Region: Pacific
Title: Decommissioning Transplantation Experiment
Actual Costs: $252,077.00 Period of Performance: FY2006-2008
Conducting Organization: University of California-Santa Barbara (Contact: Milton Love)
MMS Contact: Dr. Ann.S.Bull
Description:
Background
Recent debates regarding offshore petroleum platform decommissioning has raised questions about how these structures function in replenishing local fish stocks. Populations of many deepwater reef-associated species of rockfishes, particularly bocaccio and cowcod, have been shown to be severely depleted due to overfishing. Platforms harbor large numbers of adults of these species, provide complex structure for these fishes to associate with, and reduce fishing pressures due to difficulties fishing within and around the structure, thereby allowing the platforms to function like de facto reserves (Love et al. 2003). Decommissioning in the Pacific Region generates great debate over reefing of platforms and even if reefing should be allowed not all platforms will be reefed. Those that are not reefed will be completely removed. Removal will either kill the fish directly or remove the habitat for these reef-related species. It is unlikely that many of these fish would survive their own trip to a natural reef across the Santa Barbara Channel. Preliminary results from an MMS-funded study have determined that adult rockfish associated with platforms exhibit high site fidelity staying at their home platform throughout the year. Over 100 acoustically tagged fish have not only survived being brought to the surface and tagged but were returned to the bottom and can also be detected moving in and amongst the structure of the platforms. Since rockfish survive surfacing, acoustic tagging and treatment, and return trip to the bottom, the potential for transplantation prior to decommissioning should be tested. If adult rockfish can be transplanted and remain at a new reef in a pre-existing Marine Protected Area (MPA), then at the time of platform removal MMS could better evaluate the potential impacts, various options, and conditions proposed for decommissioning individual platforms.
Objectives
The overall objectives are to determine: 1) if adult rockfish can be successfully transplanted from platforms to Marine Protected Areas (MPA’s); and, 2) the length of time (at least one year) that the transplanted rockfish remain at their new reef or migrate back to the original platform home.
Methods
Tagging methods will be the same as those used successfully in the Site-Fidelity on-going research. 1) Fish will be caught from the base of Platforms Gilda and Gail by trap. Fish in the trap will be slowly brought towards the surface, but held at 20m depth to minimize the effects of barotrauma and thermal shock A team of divers will meet the fish at 20m and those individuals large enough (> 20 cm total length) will be surgically fitted with individually coded acoustic transmitters. The acoustic transmitters will be set at a frequency that can be received by the pre-existing PIER receivers. Prior to release, fish will be measured and tagged with an external Floy dart tag for easy visual identification from a submersible or by divers or fishers. Fish will be held in the trap after tagging until a sufficient number have been tagged and fully adjusted to the depth and temperature.

2) Fish will be held in the traps until ready for transport to an appropriate MPA in the Channel Islands National Marine Sanctuary and/or National Park waters. Trap(s) containing the tagged fish will be held in water tanks on board the vessel. After transport, the traps will be lowered and the fish released at a depth appropriate to the species and capture depth.

3) The pre-existing PIER automated acoustic receivers that are relevant to the transplanted rockfish will be recovered monthly, downloaded, and repositioned if necessary. Receivers will be serviced and fitted with new batteries every 4 months.

4) The survivorship, residence time, site fidelity, and movement patterns of transplanted fishes will be determined at the new reef home. Downloaded data will be entered and maintained in an Access database for later querying and analysis. Transmitters will have a nominal battery life of 2 years (V8SC), with some up to 4 years (V13). Residence time for individuals tagged will be determined by recording the longest period of acoustic contact relative to the expect expiration date of the transmitter. Survivorship of tagging fish will be ascertained by noted periods of no detection among and between receivers.
Importance to MMS
Decommissioning platforms off California has been a subject of considerable debate, much of which is focused on the regional importance of rockfish populations at these facilities. An on-going MMS-funded study shows that platform rockfish are reef-specific and do not move from their platform home. It is highly unlikely that these species will survive and find a new home once the platforms are removed, even if non-explosive removal techniques are used. Explosive removal will no doubt kill these species due to the nature of rockfish (large swimbladders) and their habit of close association with platforms. Knowledge of potential for transplantation of these species to Marine Protected Areas in the region is important for fully evaluating the various options and conditions (including possible mitigation measures) proposed for decommissioning California’s offshore oil platforms.
Current Status:
On-going. Several species of fish have been successfully transplanted. Surprisingly lingcod and vermilion rockfish have migrated back to the platform of original within days of transplantation.
Final Report Due: 07/23/2009
Publications:  
Affiliated WWW Sites: http://www.csulb.edu/web/labs/sharklab/research/drlowe/rockfish.shtml
Revised date: November 30, 2006
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