South Island tribe Ngai Tahu is reported to have lost $20 million from its fishing division.
The losses were detailed in a confidential draft annual report leaked to The Press newspaper.
The report also showed tourism profits from the tribe's commercial arm, Ngai Tahu Holdings Corporation (NTHC), fell $2.7m.
NTHCchief executive Robin Pratt quit in May and half the board resigned a month later.
According to the report, Mr Pratt was paid between $1.1m and $1.2m by the company last year. He rejected a suggestion the bulk of that was a golden handshake.
NTHC's performance alarmed some tribe members, the paper reported.
At least one runanga (local council) was looking at taking legal action to regain control of its fisheries shares from Te Runanga o Ngai Tahu (Tront), it said.
Tront was described by the runanga as an "insatiable money beast".
NTHC, which oversees the iwi's tourism, property, seafood and equities assets, had a $22.8m loss before interest and tax for its seafood division in the 2005-2006 financial year.
The loss contributed to an overall decrease in net surplus of more than $20m from the previous year.
Ngai Tahu Seafood's poor performance was attributed to a write-off of assets as well as rising fuel prices and poor profitability for large-volume wetfish species.
The group's tourism performance, which was down by $2.7m, was mostly because of Shotover Jet closures in January, resulting in an estimated $1.6m loss.
In a confidential email from Tront chief executive Tahu Potiki to a lawyer, leaked to The Press in May, Potiki described the relationship between Tront and NTHC as a "dysfunctional environment".
Tront is due to receive its $86m fisheries allocation from Maori Fisheries Trust Te Ohu Kaimoana this year and is proposing to form a new company to manage the assets.
