Oil Platforms’ Fishy Future

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Oil Platforms’ Fishy Future
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A male sheephead (center) swims amongst kelp bass under Platform Gina off of Port Hueneme (Photo: Ed Romero)

By Harrison Tasoff, UC Santa Barbara

Biologists and fishermen alike know that offshore oil platforms function as de facto habitats for fish. The structures climb hundreds of feet into the water column, creating a prefab reef out in open water. But many of these platforms will soon be decommissioned, and government agencies are considering the potential ecological effects in deciding how this will be done.

UC Santa Barbara postdoctoral scholar Erin Meyer-Gutbrod and her colleagues have focused their research on predicting how different decommissioning scenarios will affect the productivity of the surrounding waters. They found that completely removing a platform could reduce fish biomass at the sites by 95% on average. Meanwhile, removing just the top of the rig could keep losses to around 10%. Their forecast appears in the journal Ecological Applications.

“The key result of the paper is that the biomass and production on the platforms are much higher than they would be if the structure were removed and the area reverted to soft bottom,” Meyer-Gutbrod said.

The state of California is currently weighing several possibilities for decommissioning 27 oil platforms off the coast. The three main options at each site: leave the platform in place, remove all of it, or remove the top part of it. Each possibility has its own economic and ecological effects.

The research team set out to study the size and composition of fish communities at 24 platforms and predict how they might change under the three decommissioning scenarios. They used visual survey and bottom-trawl data on the biomass and composition of fishes living within the platforms’ underwater structure, or jacket, and the nearby soft bottom. They divided each platform vertically by habitat type, starting with the mound of shells that accumulates on the seafloor below and rising up the jacket based on the position of all the major horizontal beams.

With data in hand, Meyer-Gutbrod used mathematical models to predict how each of the decommissioning scenarios would affect biological productivity. For partial removal, she assumed that all structures within 26 meters of the surface would be stripped, as this would eliminate the need for a lighted buoy to mark the location as per U.S. Coast Guard guidelines.

The researchers found that completely removing the platform would result in an average loss of 96% of the fish biomass across all 24 sites surveyed. Meanwhile, removing just the top 26 meters resulted in a loss of only 10% of the fish biomass. Meyer-Gutbrod pointed out that this varied considerably between locations, since the jackets are in different places and depths with different fish communities. They forecasted no losses resulting from partial removal on five of the platforms and up to 44% of losses on one, Platform Gina, which sits in only 29 meters of water.

According to the researchers’ models, leaving the underwater structure of all 24 sites in place would support slightly more than 29,000 kg of fish biomass. With the top 26 meters removed, these sites could support just shy of 28,000 kg. And if all 24 platforms were completely removed, the reestablished soft bottom habitats would support about 500 kg of fish biomass.

“This result was not particularly surprising,” Meyer-Gutbrod said, “however, it was very important to demonstrate it in a rigorous way.”

The analysis revealed that fish densities were highest near the base of the jacket. The team also found that the community of fish species observed on soft bottom habitats was very different from the species congregating around platforms. This was among the first studies to specifically consider the new community that would reestablish on the soft seafloor if all of a platform’s structure were to be removed.

“In short, partial removal does not result in much loss of fish biomass or production since most of the structure sits below 26 meters of water, and fish densities tend to be higher at the platform base and shell mound than in the midwater,” Meyer-Gutbrod said.

The results are a conservative estimate of the impact the different scenarios could have on the wildlife in the area, according to Meyer-Gutbrod. “Our models only account for fish found under the platform or ‘inside of the structure,’” she said. However, the halo of marine life extends beyond the confines of a platform’s submerged jacket, well into the surrounding waters. This implies that the removal of more structure would have a larger overall effect than reported in the study.

As California weighs how to decommission the oil platforms that sit off its coast, studies like this will be critical to informing those decisions. “The people living near the Santa Barbara Channel are highly invested in the marine ecosystems here, and there is a wide range of perspectives and interest in these habitats,” Meyer-Gutbrod said. “Our goal was to provide some predictions of what these sites might look like to help guide these impending decisions.”

The study, sponsored by the Bureau of Ocean Energy Management, also gives the federal government important information in the decision-making process for future decommissioning of oil and gas platforms.

Research Biologist Bob Miller, who also was involved in the study, said, “Ultimately the decision on what to do with decommissioned platforms will be a value judgement. Our study gives some objective information that will hopefully help the stakeholders come to the best decision for people and the marine environment.”

news.ucsb.edu

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condorhiker Jun 06, 2020 01:31 PM
Oil Platforms’ Fishy Future

I'm surprised that there was no mention in the article of the effect of stirring up the drilling mud that is deposited at the bottom of each platform. If the platform is removed completely, something must be done with the drilling mud, which is full of toxins. In other discussions I've read about removing the platforms this was a major issue.

ChemicalSuperFreak Jun 05, 2020 09:15 PM
Oil Platforms’ Fishy Future

I'm surprised there is no mention of Prof. Milton Love at the UCSB Marine Science Institute. From his university website: "Dr. Love has carried out surveys of the fish populations living around natural reefs and oil/gas platforms throughout the southern California Bight". I saw his lecture at Santa Barbara's Paradise Dive Club and have a copy of his book 'Certainly More Than You Want to Know About the Fishes of the Pacific Coast'. He presents very compelling evidence on the benefits of artificial reefs created by the active platforms, as well as their remnants after being largely dismantled.

Eggs Ackley Jun 05, 2020 08:58 PM
Oil Platforms’ Fishy Future

In any scenario the wells would be shut-in so that’s probably a moot point. Eventually, any parts left in place will transmogrify into a heap of decomposing structural steel in an ugly mess on the sea floor... still creating habitat. Tough call. The energy and effort and dollars to remove completely might be better spent as others have noted, and in lieu of in-situ mitigation, create nearshore habitat enhancement projects such as constructed reefs for kelp forest habitat establishment.

hz Jun 05, 2020 07:54 PM
Oil Platforms’ Fishy Future

hw about turning them into housing, rentals, holiday camps, retreat centers , airbnb...

RHS Jun 05, 2020 06:45 PM
Oil Platforms’ Fishy Future

The oil companies are obligated to remove these dangerous installations and make the area safe from future blow outs and leakage. While it is so that the sea life has benefited from this in the short run it is less clear that the attendant harm these devices have caused does not balance that out. Never-the-less minimally the oil companies should be required to pay an amount close to what it would have cost to remove the rigs, that amount should be held in trust for the monitoring and improvement of the sites.

oceandrew Jun 06, 2020 01:33 PM
Oil Platforms’ Fishy Future

Good luck with that. Oil companies are notoriously adept at sidestepping culpability and will spend many times more to avoid it than just give in, be good neighbours and pay to clean up their messes. It's what they do. Besides all it takes is to file for bankruptcy, dissolve then re-incorporate under a new name and bingo bango they're back in biz.

yacht rocked Jun 05, 2020 04:55 PM
Oil Platforms’ Fishy Future

I'm with the lazy researcher's post. If removing the top 26m is a good solution, then go with it. Any savings in the removal costs to the oil companies can go towards sea life monitoring and enhancement.

Chip of SB Jun 05, 2020 04:50 PM
Oil Platforms’ Fishy Future

I've got a solution to all of this. Remove the oil platforms completely. Destroying the marine life is a small price to pay to be rid of the legacy of this horrible technology that has made our modern standard of living possible and provided the material to make the things we enjoy, use, and even depend on every day such as solar panels and electric vehicles. I propose installing a wind farm in the channel. There is room for hundreds of wind towers, and each would create a marine sanctuary comparable to one of the oil platforms that occupy the channel today. The hundreds of 500 foot white towers would also be a nice addition to the aesthetics of the channel, a real vision of the future.

PitMix Jun 08, 2020 01:37 PM
Oil Platforms’ Fishy Future

You're always railing about anything someone wants to do, but it is hard to tell what you are actually for, unless by default it is always the status quo. Like they say at 7-11, change is good.

Minibeast Jun 05, 2020 04:12 PM
Oil Platforms’ Fishy Future

Feeling too lazy to do the research myself, and I do have many questions: How will the lack of shade from the extant platforms affect the marine biosystem once the shade-giving parts of the platforms are removed? How much, if any platform structure is left in place, will the deterioration of these artificial reefs affect the marine ecosystem? If "we" go with only removing to 26m down, what's the material make up of the remaining parts of these platforms? As a long-time vegetarian and respecter of all fellow Earthlings, I am all for keeping intact the fish and shellfish and seaweed and whatever else constitutes the delicate marine biomass now making use of these platforms -----unless the fact that doing so becomes some huge, hazardous, toxic problem on down the line. What happens when the oil companies are no longer culpable-----does this concern outweigh keeping current marine biomass healthy and happy? Our marine life needs all the help it can get. Keep our ocean healthy. But what does the EDC have to say about this only top 26m removed proposal? If the EDC green lights it, I am all in.

macpuzl Jun 05, 2020 02:22 PM
Oil Platforms’ Fishy Future

At least something good might come from these failed relics of a ruinous technology.

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