Bishop, a highly promising rugby player, was hurled from the jetski and struck in the water by Mr Harrison's jetski. The impact caused a serious head injury.
Mourners performed a haka as his body was brought out of the water after a five-day search by police, who remain uncertain whether he could have been saved had he been wearing a lifejacket.
Mr Harrison and Mr Maaka were charged over the accident and convicted and discharged in June.
At a coronial inquest yesterday morning, Bishop's aunt Myra Iraia agreed lifejackets and helmets should be compulsory for jetski riders.
Coroner Dr Wallace Bain also noted earlier recommendations he made in his findings into the death of 9-year-old Genevieve Lewis, who died after being hit by a motor boat while waterskiing on Lake Taupo almost exactly two years before Bishop's death.
They included bringing maritime laws into line with road laws, including introducing similar offences and a system under which boats would be be registered and have warrant of fitness checks.
"On the one hand, it's understandable when you get young men, boys, having fun on a jetski, and they obviously had a ball ... [but] when you are on those sorts of vessels or vehicles capable of those speeds, you are going to get, tragically, inevitable accidents sometimes, which is why there needs be some control, surely," Dr Bain told the inquest.
Rotorua police Detective Sergeant John Wilson said police had "erred on the side of leniency" when choosing not to charge the boys with manslaughter.
After the inquest, Barbie Iraia said a compulsory lifejackets law would save other families the grief her family had suffered.
"With the lifejackets, I just can't believe how my son didn't put one on," she said.
Water Safety NZ general manager Matt Claridge said moves were being made to introduce a lifejacket law, but he saw them as "an ambulance at the bottom of the cliff".
