Operating Revenues – Unigas Pool. Operating revenues – Unigas Pool was $15.9 million for the three months ended December 31, 2021 and represents our share of the revenues earned from our 10 vessels operating within the Unigas Pool, based on agreed pool points. These vessels were acquired as part of the Ultragas transaction on August 4, 2021, and therefore there is no Operating Revenues—Unigas Pool for the three months ended December 31, 2020.
Operating Revenues – Luna Pool Collaborative Arrangements. Pool earnings are aggregated and then allocated (after deducting pool overheads and managers fees) to the Pool Participants in accordance with the Pooling Agreement. Operating revenues—Luna Pool collaborative arrangements was $8.3 million for the three months ended December 31, 2021, compared to $4.5 million for the three months ended December 31, 2020 and which represents our share of pool net revenues generated by the other participant’s vessels in the pool. The Luna Pool, which comprises nine of the Company’s ethylene vessels and five ethylene vessels from Pacific Gas Pte. Ltd., focuses on the transportation of ethylene and ethane to meet the growing demands of our customers.
Brokerage Commissions. Brokerage commissions, which typically vary between 1.25% and 2.5% of operating revenues, increased by $0.2 million or 11.9% to $1.5 million for the three months ended December 31, 2021, from $1.3 million for the three months ended December 31, 2020, primarily due to an increase in operating revenues on which brokerage commissions are based.
Voyage Expenses. Voyage expenses increased by $5.4 million or 32.4% to $21.9 million for the three months ended December 31, 2021, from $16.5 million for the three months ended December 31, 2020. This increase is primarily due to voyage expenses of the additional seven handysize vessels acquired as part of the Ultragas transaction. These voyage expenses are pass through costs, corresponding to an increase in operating revenues of the same amount.
Voyage Expenses – Luna Pool Collaborative Arrangements. Voyage expenses – Luna Pool collaborative arrangements were $6.3 million for the three months ended December 31, 2021, compared to $5.1 million for the three months ended December 31, 2020. These voyages expenses – Luna Pool collaborative arrangements represent the other participant’s share of pool net revenues generated by our vessels in the pool. The net effect after deducting operating revenues – Luna Pool collaborative arrangements was that the other participant’s vessels contributed $1.9 million to our vessels in the Luna Pool for the three months ended December 31, 2021, compared to our vessels contributing $0.6 million to the other participant’s vessels for the three months ended December 31, 2020.
Vessel Operating Expenses. Vessel operating expenses increased by $12.4 million or 43.8% to $40.8 million for the three months ended December 31, 2021, from $28.4 million for the three months ended December 31, 2020, primarily as a result of the additional Ultragas vessels joining the fleet. Average daily vessel operating expenses decreased by $120 per vessel per day, or 1.5%, to $7,999 per vessel per day for the three months ended December 31, 2021, compared to $8,119 per vessel per day for the three months ended December 31, 2020.
Depreciation and Amortization. Depreciation and amortization increased by $6.6 million or 34.2% to $25.7 million for the three months ended December 31, 2021, from $19.1 million for the three months ended December 31, 2020. This increase is as a result of the 18 additional Ultragas vessels in the fleet for the three months ended December 31, 2021. Depreciation and amortization included amortization of capitalized drydocking costs of $3.9 million and $2.0 million for the three months ended December 31, 2021 and 2020 respectively.
Impairment Losses on Vessels. Impairment losses on vessels were $63.7 million for the three months ended December 31, 2021, following an impairment review on which the estimated useful life of the vessels was reduced from 30 years to 25 years. These impairment losses relate to a write down of the carrying values of nine vessels.
General and Administrative Costs. General and administrative costs increased by $3.9 million or 62.2% to $10.3 million for the three months ended December 31, 2021, from $6.3 million for the three months ended December 31, 2020, primarily as a result of the additional general and administrative costs of Ultragas of $1.4 million, severance costs of $1.1 million and legal and other costs incurred relating to the Ultragas transaction of $1.3 million.
Other Income. Other income was $0.1 million for both the three months ended December 31, 2021 and 2020 and consists of that portion of the management fees for commercial and administrative activities performed by the Company for the Luna Pool, relating to the other participant’s vessels.
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