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The Round Goby is a small, aggressive fish that feeds on the bottom. It has the ability to proliferate in new surroundings due to its tolerance to a wide range of environmental conditions. It can spawn up to 4 times in one growing season. (www.invadingspecies.com)
The invasive Round Goby, originally native to the Black and Caspian Seas in Eastern Europe, has successfully entrenched itself in all five of the Great Lakes, infiltrating inland waters, including Lake Simcoe. This incursion is believed to have occurred through the introduction of this species to North America via ballast water from transoceanic ships originating in Europe.
The initial discovery of Round Goby within the confines of Pefferlaw Brook in 2004 sounded alarms regarding its potential impact on Lake Simcoe. Subsequent attempts in 2005 to eradicate the species proved fruitless, culminating in the establishment of a Round Goby population in Lake Simcoe since 2006. The primary concern associated with these invasive fish arises from their aggressive feeding habits, which encompass the consumption of fish eggs, insects, and various small organisms. They directly engage in competition with native fish species, such as the Mottled Sculpin, for essential food resources.
Owing to their insatiable appetite and remarkable reproductive capacity, with the potential for up to four breeding cycles per season, Round Gobies have undergone rapid proliferation and dissemination throughout the expanse of Lake Simcoe. This proliferation poses a significant threat to the ecosystem of the lake.
The native Mottled Sculpin looks very similar to the Round Goby. The main difference is the sculpin does not have a black spot on its dorsal fin and has 2 pelvic fins and not one like the Goby. (www.invadingspecies.com)
Despite their competition with native fish species, Round Goby have evolved into a pivotal component of the Lake Simcoe food web. Species such as Yellow Perch, Lake Trout, and Whitefish now enjoy bountiful feasts on the burgeoning Round Goby populations. Numerous anglers have reported encounters with Goby-stuffed bellies in their catches, prompting them to adapt their tactics in order to locate and hook their desired fish species. Furthermore, anglers have observed that Smallmouth Bass, Lake Trout, and Whitefish have exhibited larger-than-average sizes, a phenomenon attributed to the abundant and easily accessible Round Goby population within the lake.
In the historical context of Lake Simcoe, Sportfish predominantly relied on Lake Herring, Rainbow Smelt, and Shiners as their primary forage. Vast schools of baitfish once roamed the lake, serving as prey for larger predatory fish. Seasoned ice anglers frequently employed bait options that closely resembled these elongated, silvery fish, employing spoons, Jigging Rapalas, shiners, minnow swim baits, and various other vertical jigging lures. It was not unusual for anglers to engage in their pursuits at depths ranging from 80 to 120 feet.
At present, Lake Herring, Smelt, and Shiners continue to constitute a significant portion of the diet for numerous sportfish inhabiting Lake Simcoe, and traditional baiting techniques remain prevalent. Nevertheless, the angling landscape is undergoing a noteworthy transformation as artificial baits meticulously crafted to mimic Round Goby garner increasing attention.
Pioneering this evolving angling methodology are coveted bait selections like the "Meeg's," the Badd Boyz, and petite brown soft plastic drop shot baits, typified by the Set the Hook "Drifter" and "Grumpy Baits" goby soft plastics. These bait options have become essential components in the tackle boxes of Simcoe's anglers due to their uncanny resemblance to Round Gobies. Their efficacy in replicating this invasive species has firmly established their presence within the toolkit of modern-day anglers.
The evolution in angling approaches extends beyond bait selection to encompass preferred fishing locations. Ice anglers are currently discovering Lake Trout and Whitefish in shallower waters than traditionally expected. Remarkably, these fish are frequently encountered in depths of less than 30 feet, marking a departure from established norms. This phenomenon is attributed to their pursuit of Round Goby, a prey species that thrives in hard, rocky substrates and shallow shoals. It is noteworthy that while these fish exhibit a preference for rocky and harder bottoms, they are also adaptable to sand and silt substrates when necessary.
Ice fishing baits that have performed well for Simcoe Gamefish due to their Goby like appearance.
A Lake Simcoe Whitefish that fell victim to a goby hair jig.
While Round Goby offer an alternative food source for several fish species within Lake Simcoe, predicting the long-term consequences for the aquatic ecosystem remains a complex challenge. However, there is a notable positive aspect to their presence: Round Goby have shown an inclination to consume the invasive Quagga and Zebra Mussels, which have drastically altered the Lake Simcoe landscape. These freshwater mussels function as filter feeders, extracting substantial quantities of plankton and nutrients from the water, thereby depleting the lake of essential nutrients required by native fish species. By preying upon these mussels, Round Goby may play a pivotal role in unlocking nutrients from the lake bottom and redistributing them throughout the aquatic food web, potentially mitigating some of the adverse effects caused by the invasive mussels.
Laboratory investigations have yielded precise insights into the dietary habits of Round Goby, revealing their predilection for Lake Trout eggs and fry. An illuminating study conducted in Lake Erie further underscored this behavior. When nesting Smallmouth Bass were temporarily extracted through angling efforts, Round Goby promptly infiltrated the vacated nests and, on average, devoured approximately 2000 eggs before the vigilant male bass was reinstated. Significantly, in instances where the male bass remained undisturbed at his nest, no eggs or larvae fell prey to Round Goby consumption.
The impact of the Round Goby extends beyond aquatic environments, posing a significant concern for researchers. There is a strong belief that the Round Goby is implicated in the occurrence of Type E botulism outbreaks. This bacterium has the potential to infect fish-eating avian species, including gulls, loons, and cormorants, significantly impairing their mobility, rendering them unable to fly or hold their heads aloft. Tragically, these afflictions can lead to the unfortunate drowning of infected birds. This toxin is transmitted through a complex chain: an infected mussel is consumed by a Round Goby, and subsequently, the infected goby is ingested by a bird, facilitating the spread of the toxin within the ecosystem.
The presence of Round Goby in Lake Simcoe necessitates ongoing and vigilant monitoring to comprehensively assess their potential impacts on the Lake Simcoe fishery. This includes understanding the dynamics of coexistence between this non-native species and popular gamefish species.
While anglers currently relish the benefits of larger catches and embrace innovative techniques for targeting popular game fish, alluding to the positive influence of Round Goby, the long-term implications for the Lake Simcoe fishery remain uncertain. The need for continuous evaluation and research is imperative to gain a comprehensive understanding of how this invasive species may ultimately shape the ecological balance of Lake Simcoe's aquatic ecosystem.
Round Goby's feed on Zebra and Quagga mussels which may help to redistribute important nutrients from the bottom back into the aquatic foodweb.
Round Goby may be linked to Type E Botulism. The toxin can be passed to birds that eat Gobies which have eaten infected mussels. (Photo credit: https://toronto.citynews.ca)
Information from this article was gathered from:
Cudmore, Becky & Koops, Marten. (2007). Risk assessment of round goby (Neogobius melanostomus) to Lake Simcoe, Ontario: A Quantitative Biological Risk Assessment Tool (QBRAT) case study.
http://www.natureconservancy.ca/en/what-we-do/resource-centre/invasive-species/round-goby.html
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