Biology professor spends nights making babies — salmon babies, that is

A biology professor at Memorial University and his team are helping to repopulate Rennie's River in St. John's.

Meet MUN's Craig Purchase, 'salmon daddy' who has fertilized thousands of baby fish

Craig Purchase, a.k.a. Salmon Daddy, holds an incubator box during an interview on the St. John's Morning Show. (Paula Gale/CBC)

A biology professor at Memorial University has been busy this fall, spending several late nights making thousands of babies — salmon babies that is.

Salmon daddy Craig Purchase is the coordinator for a project that is looking to reintroduce Atlantic salmon into Rennie's River in St. John's, an effort that has been ongoing for the last six years.

The males are always ready, they're like guys lined up at the bar.- Craig Purchase

The complicated process involves moving salmon eggs from Grand Falls-Windsor to St. John's, then fertilizing them in a lab and placing them in the river, all of which has to happen within in a 12-hour window.

It all starts around 10 a.m. when eggs are taken from ready females at the Grand Falls fish ladder. Not all the female fish are ready at the same time, so this fall eggs were taken in four separate batches. 

The salmon eggs come from the fishway in Grand Falls-Windsor and are brought to St. John's to be fertilized before being placed in Rennie's River. (

The sperm can be collected at anytime during the spawning season.

"The males are always ready, they're like guys lined up at the bar," Purchase told the St. John's Morning Show on Tuesday, the morning after the fourth and final batch of the year was fertilized.

After the eggs are collected they're put in mason jars, placed on ice and shipped to Purchase on the DRL bus service.

Starter home

Purchase then picks them up in Mount Pearl — in much the same way a university student would pick up a care package sent from home around the bay — and brings the eggs to his lab.

"We take the eggs, put them in a bucket, take the semen sample from the males and mix it with the eggs and we add a little bit of water. That will activate the sperm to swim and within a few seconds the fertilizations take place."

The sperm have a lifespan of only 30 seconds, so there's not much time.

DRL Coach Lines doesn't just transport university students and people with medical appointments across Newfoundland. It also is used to bring thousands of salmon eggs to St. John's to be fertilized. (

Mixing in the bucket simulates what happens naturally in a fast moving river, where sperm and eggs from many different salmon – and brown trout – mingle as everything floats downstream.

In fact, one of the main things Purchase is researching through the salmon program is how brown trout, which are not native to North America, are breeding with Atlantic salmon in Newfoundland rivers.

"Although the females will choose a male to spawn with, other males don't care and will sneak paternity from him," he said. "They will squirt semen into the mix and fertilize some of the eggs."

Moving on up ... to a condo

Once the eggs are fertilized in the lab, they are moved into incubator boxes, which Purchase calls salmon condos — technology developed about a decade ago.

Each unit allows 200 fertilized eggs to be housed without the risk of contaminating each other with fungi.

"Each egg gets it's own apartment," Purchase said.

These salmon egg incubators, called 'scotty boxes' or 'salmon condos', are a recent technology that reduces the chance of eggs being contaminated. (Submitted photo)

The box of eggs is then laid in Rennie's River for a few months until baby salmon finally swim outside and into the soil below.

After hatching in the spring, the fry live in the river bed for several months until they eventually move into the open river sometime in May.

Research projects

While the main goal of the program is to reintroduce salmon back into the river, Purchase is also conducting a number of research projects.

Salmon eggs usually hatch in the spring, when the fry move into the river bed. (Submitted photo)

That includes looking into the effectiveness and best practices for the incubators, the hybridization of brown trout with Atlantic salmon and other areas of salmon reproduction.

The project is also meant to help educate the public on the salmon life cycle through outreach programs with school children who release fry into the river in the spring.

With files from St. John's Morning Show