LYNN-With City Hall closely watching all spending, the supply of dockside gasoline and diesel fuel at Seaport Landing Marina will be temporarily limited as boating season approaches.David McQuarrie, the marina dock master, said city officials curtailed the purchase of fuel from John’s Oil because of fluctuating market prices. Fuel prices during the winter were hovering around $4 per gallon but have since dropped.”It was a smart decision to wait,” said Harbormaster Jim Perry. “We didn’t want to get stuck with 5,000 gallons of fuel at $4 a gallon.”According to Perry, the marina has a limited amount of gasoline and diesel fuel in its tanks but will top them off in mid-April. “We have enough for the lobstermen to fill up and for somebody who might need fuel in an emergency, but that’s about it,” he said. “The boating season really hasn’t begun yet. There are a few boats out, but most won’t be down here until June.”Seaport Landing Marina, owned and operated by the city, is home port to hundreds of power, sail and fishing boats.An online appendix of marina fuel prices in Massachusetts shows pre-winter per-gallon averages of $3-$3.50 for gasoline and $3.30-$3.70 for diesel. At the Newburyport Harbor Marina, prices in December were $2.99 for gasoline and $3.29 for diesel.