"The netball trial is on a week before the rowing trials and it was it a bit much for Sammy to take on both in such a short timeframe - she's only 15 and has it in front of her," Murphy said.
The U18 North Island trials are scheduled for three days at Lake Karapiro starting April 20, while the national junior trials run for a week at the same venue from April 22.
Collegiate boys and girls coaches Barry Banks and Fiona Symes said the selections were clear recognition of their respective rowers performances over recent regatta culminating in the Maadi Cup at Lake Karapiro last month.
"These guys are young and the exposure at this level will assist them greatly - they deserve to be there," Symes said yesterday.
"Jessica, who is off to trial for the national junior team, also has athletic duties and joined us late to become stroke of our girls eight with a minimum of training.
"She then rowed in the singles and came fifth in the final of the U16 at the Maadi Cup.
"The junior trials are on pretty much at the same time as the North Island U18 trials, so the other girls will get a feel for what to expect in the future when they reach that level.
"They have done well at regattas, but trials are a completely different kettle of fish," Symes said.
Banks said his boys had worked hard under his guidance over the past few years and were making significant progress.
"Our plan is to try and keep them in rowing after they finish school and this sort of recognition helps that.
"But our boys have made huge progress over the past three years, although Jamie [Clark] came to us just last season after the Christchurch earthquake and we're glad he did, and Edward [Phelps] got a late call-up for the U18 North Island trial," Banks said.
Coach Ian Weenick has had Back, Murphy, Gowler and Nugent-O'Leary in a training camp lately and rates them all talented rowers with potential for even higher honours.
"These girls are good rowers who will also do well long term," Weenick said.