October 24, 2007
Invasive Round Gobies off the Oshawa / Bomanville shoreline (Lake Ontario)
Winston Stairs, one of the regular readers of this site, recently submitted this report to me. He previously reported on Bloody Red Shrimp.
If my research is accurate, my report (below) is the first to document round gobies* off the Oshawa / Bomanville shoreline. Previous reported locations were Hamilton and Picton, Ontario.* - Round Gobies (Neogobius melanostomus) are a non-indigenous species of fish from the Baltic region (Europe) introduced into the Great Lakes basin back in 1990. They are believed to have come in by way of ballast water on ships entering the Great Lakes system through the St. Lawrence River. They have few natural predators and are a stressor to the ecosystem by competing for food stores of native species of fish (bass, perch, pickerel, etc.).
Subject: Neogobius - minor report - 10/21/2007
Regrettably, conditions were less than optimal today for conducting a full and complete survey of Neogobius melanostomus on the wreck of the Juno off Bomanville shore.
Horizontal visibility was estimated at 4'-5' (1.2m) and aquatic (piscine) life was virtually non-existent - one sizeable small mouth bass (Micropterus dolomieu) and 5 small (5-6cm) round gobies (N. melanostomus).
In addition, the density of suspended particulate matter made photography virtually impossible due to backscatter from the flash.
Having seen many round gobies on the Juno in past, I had hoped to run a 10m transect line and conduct population counts within a 1m quadrat along the line. However, seeing the conditions and scarcity of gobies I opted to provide a brief, informal report.
Date: October 21, 2007
Time: 09:50 - 10:30 EDT (13:50 - 14:30 UTC)
Location: Lake Ontario, wreck of 'The Juno', off Bomanville shore (GPS 43 53.157 / W 78 40.491)
Depth: 12' (3.65m) max., 10' (3.04m) average
Temp: 52 deg F (11.1 deg C) at depth
Visibility: 5' (1.5m) horizontal est. (Vertical transparency using Secchi disk not conducted)
Gobies Present: Yes
Number: 5
Length: 5-6cm avg.
Benthic Substrate: Predominately sand (fine grain) with rocky inclusions (avg. stone size - 4cm dia.)
Spatial Distribution of Neogobius nests: None identified
Estimated Density of Neogobius nests/cavities: No findings
Nearest neighbour distribution of nests: None identified
Size of nest opening: No findings
Size of nest guarding male: None present
Surface area of nest covered with eggs: No findings
Posted by Dida at October 24, 2007 10:18 AM
