There are plenty of high-yield income shares listed on the UK stock market. But right now, Harbour Energy (LSE:HBR) and Energean (LSE:ENOG) stand out from the crowd with both offering a dividend yield of 9.7%.

With both oil & gas shares taking a bit of a tumble over the last 12 months, it isn’t surprising to see the yield rise. And while such a large payout does signal risk of a payout cut in the future, there are always some rare exceptions.

So are these shares a classic dividend trap? Or could there be a lucrative passive income opportunity here?

Opportunities in fossil fuels

Harbour Energy and Energean are both independent oil & gas producers. Harbour’s the larger producer operating a geographically diversified portfolio across the UK North Sea, US Gulf Coast, Latin America, and North Africa, while Energean’s concentrated in the Mediterranean with the bulk of production near Israel and Egypt.

However, the way these companies generate revenue is a bit different. Harbour sells its oil & gas directly to global commodity markets, making it highly sensitive to fluctuations in global oil & gas prices.

By comparison, Energean relies primarily on long-term take-or-pay contracts. In oversimplified terms, these agreements ensure that customers buy a fixed volume at a fixed price that often rises with inflation. While that does mean Energean doesn’t benefit as much as Harbour Energy when oil prices rise, it also doesn’t suffer as much if prices fall.

Why are the yields so high?

The high-yield situation is different for both companies. Starting with Harbour Energy, the chief concern revolves around its 2024 acquisition of the Wintershall Dea project for $11.2bn. While this deal doubled its production capacity overnight, the company also became responsible for around $4.9bn of Wintershall Dea’s outstanding debts.

For the time being, current oil prices are enabling free cash flow generation to service its new obligations as well as maintain dividends. However, due to the group’s sensitivity to swings in the commodity markets, that could change very quickly if oil & gas prices drop.

In its May 2025 trading update, management revealed that a $5 drop in the price per barrel of Brent oil could wipe out $115m in free cash flow. And with fears of lower prices in 2026, the dividend could be vulnerable.

Due to its revenue model, Energean doesn’t share this weakness. However, with over half of its production located off the coast of Israel, investors are understandably concerned about potential geopolitical escalation. After all, the region isn’t exactly the most stable area of the world right now, which could lead to production disruptions.

What’s the verdict?

With both income shares facing substantial risks, it isn’t surprising to see the yield rise so high. This is a classic high-risk/high-reward scenario. However, out of the two companies, Energean seems to have an upper edge in terms of dividend sustainability in 2026.

Providing that production remains undisturbed, its lower sensitivity to commodity price swings offers far more cash flow transparency and resilience. That’s why I think it deserves a closer look from more aggressive income investors who are comfortable with volatility.

Having said that, I’m not rushing to buy the shares today. Instead, I’ve got my eye on other lucrative and lower-risk income opportunities for my portfolio.