Cormorants

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Originally Posted by Gun Nut

I’m always amused in attempting to find historical information on the internet how sketchy it is. For instance I can find information on when the Cormorant population in the Great Lake basin began to explode. But information on when residential fishing licencing came into full swing doesn’t appear to be available. I stopped fishing at that time, and it’s so far back I’ve lost track of when it began.. I recall after the fishing licence got established they started fish restocking to give fishermen some return on the money they were spending on licencing. The earliest restocking started in the Great Lake basin and eventually after they received enough complains from those further back, they move on into stocking the back lakes. They dumped a lot of fry into the Great lake basin to improve the game fishery. After recalling the Delmar Peninsula thing with the corn harvest and the geese, I’m half wondering if the surplus of food from the restocking of game fish in the Great Lake basin may have been the biological trigger, that caused the Cormorants to stop their northern migration and take up residence in the basin. Something to think about.

You don’t stop hunting because you grow old. You grow old because you stop hunting.
- Gun Nut

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The amount of fish being stocked in the lakes would not be enough to cause numbers to increase the way they have. Cormorants began showing up in the Rondeau Bay, Lake Erie areas back in the early 70s, long before any fish stocking took place.

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Originally Posted by rick_iles

The amount of fish being stocked in the lakes would not be enough to cause numbers to increase the way they have. Cormorants began showing up in the Rondeau Bay, Lake Erie areas back in the early 70s, long before any fish stocking took place.

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Do have any dates for the initial stocking? The graph I'm looking at suggest some rather low numbers up until the beginning of the 80s. There appears to be a small jump around 84, with a big explosion coming in the late 80s and early 90. Over 10,000 nesting sites by 1991.

You don't stop hunting because you grow old. You grow old because you stop hunting.
- Gun Nut

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Originally Posted by Gun Nut

Do have any dates for the initial stocking? The graph I'm looking at suggest some rather low numbers up until the beginning of the 80s. There appears to be a small jump around 84, with a big explosion coming in the late 80s and early 90. Over 10,000 nesting sites by 1991.

You don't stop hunting because you grow old. You grow old because you stop hunting.
- Gun Nut

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No.... if my memory serves me correctly, the initial fish stocking was in the mid to late 80s, when coho were introduced. Again, I doubt that the number of fish stocked would impact cormorant numbers. I would suggest that their numbers went up as the lake water clarity improved due to zebra mussels. Prior to that, the lake was so dirty they likely couldn’t find fish. IMHO, factors including climate change and lake water clarity improvements contributed to the explosion of cormorant numbers.

Timing coincides with the round goby invasion. I wonder what percent of their diet is gobies. Wouldn't be surprised if it's the number one fish by total biomass in lakes like Erie now. I remember reading that they figure the big increase in Red-necked Grebe populations in the Great lakes is attributed to this food source.

https://greatlakesecho.org/2010/07/1...sh-study-says/

Looks like it could be a factor

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Originally Posted by Fenelon

https://greatlakesecho.org/2010/07/1...sh-study-says/

Looks like it could be a factor

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They may be eating fewer game fish because there are less game fish to eat..

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Originally Posted by Snowwalker

They may be eating fewer game fish because there are less game fish to eat..

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If you have ever seen a large flock of Cormorants feeding, you can see they are not feeding at the bottom, where gobies live. They are clearly feeding on schools of fish.

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Originally Posted by rick_iles

If you have ever seen a large flock of Cormorants feeding, you can see they are not feeding at the bottom, where gobies live. They are clearly feeding on schools of fish.

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Till the schools of game fish are gone, then and only then would they maybe feed on Gobies.

Which was my point. When the game fish are depleted they have to switch to Gobies. Does not help the game fish populations.

Karen found a dead Cormorant this spring, it had a large Carp down it's throat but got tangled in fishing line and drown(?). They can swallow some pretty large fish