species

Saturday September 8, 2018

Editorial Cartoon by Graeme MacKay, The Hamilton Spectator – Saturday September 8, 2018

Scientists urging people to stop dumping aquarium and market fish into Hamilton Harbour

Harbour scientists say they have been finding some strange new creatures in Hamilton Harbour this summer, suggesting people are dumping aquarium and fish market species into the waters.

June 24, 2015

“We’ve seen some fish that really should not be there and it’s really a sign of people purposefully and irresponsibly and illegally releasing fish into Hamilton Harbour,” said Becky Cudmore, senior science adviser on aquatic invasive species with Fisheries and Oceans Canada.

Among the findings are four tilapia fish and a type of aquarium catfish. This is on top of an established population of goldfish, the outcome of untold numbers of people emptying their aquarium fish into the bay and Cootes Paradise.

“What we are seeing with goldfish is something we don’t want to see happening with other species,” she said.

She believes the tilapia, a non-native species originally from the Middle East and Africa, were bought at a fish market and then released into the harbour in a misguided effort to save the fish from being eaten.

“It’s not fair to the fish because they are not meant to be in that water,” said Cudmore. She urged people with unwanted aquarium fish to take the fish to pet rescue centres or back to the store where they bought them.

She expects tilapia in the harbour will die out over the winter because the species prefers tropical environments. But some could survive by using warm water effluent from Hamilton steel mills as an overwintering haven.

Tys Theijsmeijer, the head of natural lands for the Royal Botanical Gardens, says as well as adversely affecting native species, introduced species can bring new diseases to the ecosystem. (Source: Hamilton Spectator) 

 

Saturday January 9, 2015

Editorial Cartoon by Graeme MacKay, The Hamilton Spectator Ð Saturday January 9, 2015 Hamilton Harbour becoming giant goldfish bowl Millions of tiny ones are swimming around after a summer that saw weather and water conditions turn Cootes Paradise into a massive breeding ground for the carp-like creatures. The non-native fish species Ñ that people buy as pets and sometimes, ill-advisedly, release into local waterways Ñ have suddenly gone viral in the bay and have become the latest complication in its rehabilitation. It used to be that goldfish in the Ontario outdoors had a very low survival rate and little success at reproducing. But officials at the Royal Botanical Gardens and the Department of Fisheries and Oceans Canada say that's been changing in recent years in the warmer weather we've been experiencing. They've noticed exponential increases in numbers being counted at the Desjardins Canal Fishway Ñ from 20 or less per year in the late 1990s to 2,500 this past spring. And early this winter, millions of five centimetre, young-of-the-year goldfish have been seen swimming in giant schools at various locations in the harbour, including the section of the canal below the railway bridge. "They seem to be heading toward taking over," says Tys Theysmeyer, the head of natural lands for the RBG. Becky Cudmore, an invasive species expert with Fisheries and Oceans Canada, says it's a problem being noticed at numerous locations in the lower great lakes, with Hamilton Harbour being a particular hot spot. "With increased warming trends we're seeing an increased ability of some fish species to survive in areas where we wouldn't think they could survive," she says. Theysmeyer says low water levels in the early summer in Cootes Paradise Ñ where fish tend to reproduce Ñ that suddenly rose later on also assisted goldfish reproduction. Shallow water is good for eggs, slightly deeper water is better as the tiny fish start to swim around. When water levels jumped 50 cms, d

Editorial Cartoon by Graeme MacKay, The Hamilton Spectator – Saturday January 9, 2015

Hamilton Harbour becoming giant goldfish bowl

Millions of tiny ones are swimming around after a summer that saw weather and water conditions turn Cootes Paradise into a massive breeding ground for the carp-like creatures.

The non-native fish species — that people buy as pets and sometimes, ill-advisedly, release into local waterways — have suddenly gone viral in the bay and have become the latest complication in its rehabilitation.

It used to be that goldfish in the Ontario outdoors had a very low survival rate and little success at reproducing.

But officials at the Royal Botanical Gardens and the Department of Fisheries and Oceans Canada say that’s been changing in recent years in the warmer weather we’ve been experiencing.

They’ve noticed exponential increases in numbers being counted at the Desjardins Canal Fishway — from 20 or less per year in the late 1990s to 2,500 this past spring. And early this winter, millions of five centimetre, young-of-the-year goldfish have been seen swimming in giant schools at various locations in the harbour, including the section of the canal below the railway bridge.

“They seem to be heading toward taking over,” says Tys Theysmeyer, the head of natural lands for the RBG.

Becky Cudmore, an invasive species expert with Fisheries and Oceans Canada, says it’s a problem being noticed at numerous locations in the lower great lakes, with Hamilton Harbour being a particular hot spot.

“With increased warming trends we’re seeing an increased ability of some fish species to survive in areas where we wouldn’t think they could survive,” she says.

Theysmeyer says low water levels in the early summer in Cootes Paradise — where fish tend to reproduce — that suddenly rose later on also assisted goldfish reproduction. Shallow water is good for eggs, slightly deeper water is better as the tiny fish start to swim around.

When water levels jumped 50 cms, doubling the volume of water, Cootes Paradise “basically turned into a goldfish factory,” he says.

Most troubling, he says, is when the invading fish become fully grown. They can reach more than 40 cms in length, much smaller than mature carp, but big enough to cause similar damage to a fragile ecosystem.

Carp are destructive because they crowd out other species and are constantly churning up the bottom in their search for food. This inhibits the growth of plants and indigenous fish species.

The RBG has taken extensive steps to push them out of Cootes Paradise, most notably by using the fishway that operates like a gate for hand sorting of desirable and non-desirable species trying to return from Hamilton Harbour to Cootes in the spring. Those efforts have been largely successful.

But huge populations of carp remain in the harbour throughout the year and are a factor in discouraging the growth of desirable fish species such as pike and bass there. (Source: Hamilton Spectator)