A crowd of just 5217 turned up to watch the match between the Highlanders and the Lions at Carisbrook on Saturday night, a game the Lions won in the last minute, winning 26-22.
Clark said though they had no expectations as to crowds this season he would have thought a larger number would have come through the gate on Saturday night.
"It was disappointing to see a crowd of that amount considering how well the team has played this year. With the importance of the game you have to be disappointed with the lack of support," he said.
"We understand the Lions and the South African teams in general do not draw well but this was a really, really important game for the Highlanders and I would have thought the players would have deserved some more support."
South African sides have traditionally been unable to draw teams to Carisbrook and those low crowds in part contributed to the decision to move to a conference system where more derbies between teams from the same country are played.
The franchise relies on gate money and sponsorship for income.
More than 20,000 had turned out for the match between the Highlanders and the Crusaders in March while about 12,000 watched the game against the Blues last month.
The cold weather and the night kick-off did not help attendance but television demanded games are played at night.
The competition has also been extended and is being played well into winter, while last year the round-robin part of the tournament was over by the middle of May.
Clark said it was vital fans came along to support the franchise this Friday night, for the match against the Force.
"This is a must-win game and is the last time the team will be seen here this season. Why would you not want to go see them?
"We would have to really question whether there is a future for the franchise in this region if we don't get a good crowd on Friday night.
This team is in play-off contention, it is the last-ever game at Carisbrook for the team, there is the unveiling of a new jersey. So why wouldn't people come along?"
The Force arrived in Dunedin on Saturday and trained at Montecillo yesterday.
