Wednesday, January 15, 2020

Tomcod Tomfoolery

Tomcod (Microgadus tomcod), also called winter cod or frostfish, are native to the North American Atlantic coast from the Gulf of St. Lawrence to Virginia. Their tolerance of cold water and indeed their preference of it now means they are extremely diminished in abundance in many places. CT is one of those places. A combination of warming water temperatures as a result of climate change, diminished tidal marsh habitat, and pollution are keeping tomcod from making the sort of comeback many of us wold like to see. In the Hudson River though a population of tomcod persists due to a freakishly fast incidence of evolution. The Hudson River tomcod have evolved an immunity to PCB's that would otherwise have killed them. This National Geographic article goes in depth and is worth a read. Ironically, the same genes found in the Hudson River tomcod have been found in tomcod caught by CT DEEP in the Niantic River. In recent years tomcod have made a very minor resurgence in CT waters and are around in small numbers in the winter. So Leo, Noah and I went to try to find some.


The waters we intended to fish had been confirmed in recent years to have tomcod, however we had no real way of knowing if they would be there while we were, if we cold actually effectively get to them, or if they were going to be in an eating mood. The first location had tomcod last winter as confirmed by DEEP, but it was very much in question whether we would be able to reach them. In hindsight I'm not sure we would have caught any whether they were in that river at the time or not, and I'm not sure they were. This has been a very warm winter. That day was cold, but on the whole things have been extremely mild. Tomcod aren't big fans of that sort of thing. Leo did kill the skunk though, coaxing a number of tiny banded killifish out of the rocks.


The second location we tried has reliable reports of hook and line catches, and on paper seemed very promising. Choose the wrong tide though and it doesn't matter. We chose a bad tide. Our lines collected trash, the felt soles on my Korkers collected snow, but we collected no tomcod. 



If a fish like tomcod can evolve rapidly to survive human pollutants, it gives me hope. What a remarkable little fish. But it still is one I'm not sure I'll ever catch on the fly. If I do, it is more than likely going to have to be through a hole in the ice.  
Until next time.
Fish for the love of fish.
Fish for the love of places fish live.
Fish for you.


Thank you to my Patrons; Erin, David, John, Elizabeth, Brandon, Christopher, Shawn, Mike, Sara, an Leo for supporting this blog on Patreon.


4 comments:

  1. That's a really cool adaptive response... Indeed it does give some hope, yet also suggests how substantial the risk is to see dramatic reductions or elimination of many species. Good luck on this quest!

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    1. Agreed, and the fact remains that even though there are still some tomcod around in Southern NE, there is effectively zero chance there will ever be the kind of fishery there used to be in NJ, LI, and CT.

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  2. Any idea if the browns in the housatonic have developed the same immunity to PCBs as the Hudson strain tomcod? MA only stocks the housy with browns bc they discovered a wild population of browns but that area of the housy is loaded with PCBs bc of GE.

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    1. No. Brown trout almost certainly were less susceptible to mortality because of the PCBs from the get-go than tomcod. There's been no documentation of a rapid evolution incidence in brown trout due to PCB contamination.

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