The eyes of government scientists are excitedly focused on a captivating species of sport fish in Hamilton Harbour that has defied the odds and prospered after years of stocking efforts.

And come spring, with tracking equipment and other technology, they will watch closely for evidence that maturing members of the walleye community will make it to the next life cycle stage and reproduce.

The fish of note were stocked by the provincial Ministry of Natural Resources in 2012 and are reaching an age where they are old enough to spawn. If walleye in significant numbers successfully rear young, it could set a chain reaction of improvements to the bay, experts say.

"It's one thing to stock the bay with a sport fish. It's another to have naturally producing populations," said Chris McLaughlin, executive director of the Bay Area Restoration Council.

"It's a huge reward after 25-30 years of effort in restoring fish and wildlife habitat that native predators can be restored. It's a huge win for public perception of the health of the harbour because it is so widely perceived as lifeless and that is far from true."

Last summer, workers from Fisheries and Oceans Canada outfitted 25 walleye with telemetry transmitters to keep track of their movements. In April, they plan to double that number and make use of set of receivers around the bay that "ping" and record every time one of the fish goes by.

They know a substantial population — which has reached 40 centimetres to 73 centimetres in length — has survived because anglers are catching them, as are government catch-and-release trap nets.

That's a success in itself because a previous effort to introduce walleye to the harbour in the 1990s didn't pan out.

But the question now is whether the latest stocked fish will find the harbour a suitable place to rear young. There are all kinds of issues that could potentially affect the outcome, such as the availability of suitable habitat, predators, contaminants and water temperature.

"They are doing really well, growing really well. We just don't know what is going to happen next," said Christine Boston, of Fisheries and Oceans Canada, the lead researcher in the monitoring project.

"Now that they are getting towards reproductive age, we want to know where they are going," said Boston, who works out of the Canada Centre for Inland Waters on the Beach Strip. "Are they staying in the harbour? Are they going out? Are they going to spawn? What habitat are they using?"

Walleye like to spawn in clean coarse substrate such as gravel or cobble in lakes or rivers in the spring. Water temperatures of 7 to 10 C cue the onset of spawning, said Colin Lake, of the Ministry of Natural Resources. "Stable temperatures and water levels are important for proper development of the eggs and fry."

Sizable numbers of naturally produced walleye young will be seen as a major victory for the much maligned body of water that has been undergoing massive remediation efforts since the 1980s. The bay is still deemed an "area of concern" by the International Joint Commission.

A healthy bay, Boston said, should have 20 per cent sport fish among its aquatic life. As it is now, there is less than 10 per cent.

Predator species such as walleye help create a healthier ecosystem. For one thing, large populations of walleye would feed on young carp and goldfish, helping to keep populations of those non-native species under control.

Carp and goldfish, whose numbers have increased exponentially over the years, are problematic because they crowd out native species and are constantly stirring up the bay bottom. This inhibits plant growth and makes the water murky.

A bay filled with sport fish is not only a plus from an ecological perspective, it will go a long way in enhancing the harbour's image, says McLaughlin.

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"Reproducing walleye would be the Holy Grail for restoration. This is a significant milestone in this process. It would be a feather in the cap of entire remediation program."