Cod

My high school science teacher told us, “The more you know, the more you know that you don’t know,” Boy was he right! Actually, that goes back to Socrates, but that’s another story. In March, 2026, I started using AI, and that makes everything easier. I have been using Grok 4, because that is supposed to be the most technically oriented. Below are the responses to questions that I had about cod.

Question 1: Studies of cod show they have low length at age, weigh at age, fecundity, and recruitment. In addition, the forage base has a lot of low lipid components like invertebrates and crustaceans. Could they be related and would more high lipid forage fish like herring, mackerel and menhaden help?

QUESTION 2: I have heard that there might be a correlation between cod and alewives, that cod might gather at the mouths of rivers for juvenile alewives, and they fatten up on them prior to spawning? is there anything to that story?

Question 3:The current US Atlantic Cod population demonstrates low weight at age, low length at age, low fecundity and low recruitment. This is believed to be caused by a diet that is low in lipids. The solution is to reduce harvesting of high lipid forage fish menhaden, herring and mackerel. Will the improved diet over time improve their ability to tolerate any increase in water temperature?

Question 4: To follow up on the previous question, would a healthy, well nourished fish population have a better chance of adapting to small changes in temperature over time?

Cod have been an iconic part of American history since the Portuguese first started fishing New England waters in the early 1500’s. Since the cod population collapse in the 1990’s, there has been a lot of research done on them, including a very robust study done in the straight between Sweden and Denmark. (LINK) Cod appear to be the worst case scenario in the Atlantic fishery, as they have undergone many decades of overfishing, their favorite prey, Atlantic herring have also had a population collapse, and the herring’s favorite food, the calanus zooplankton, are disappearing from the southern parts of their range because of warming waters. So this sounds like a hopeless case. Our only available solution for the rest of the Atlantic fishery is to close down the menhaden reduction fishery. What’s the chances of cod, which feed in the mid-water part of the water column, change their habits and start feeding on menhaden, which stay near the top of the water column? When the first TAC on menhaden was imposed in 2013, there was a large expansion of menhaden northward to the NY Atlantic Bight and the Gulf of Maine. Closing the menhaden reduction fishery would expand on the 2013 expansion into the GOM even more, which would create an abundance of menhaden there. As we have seen above, there is a history of cod coming to shallower waters to feed on alewives, both spring and fall. Historically, cod were caught just off Pt. Judith from December to April. A friend of mine caught a 26# cod from the West Wall in Pt. Judith about 60 years ago. Menhaden are now wintering in the NW Bight area. The Optimal Foraging Theory (OFT) (LINK) is a framework in behavioral ecology that predicts animals will forage in ways that maximize net energy (or fitness) gain relative to costs. What’s the chances of cod changing their diet and start feeding on menhaden? With the expected abundance of menhaden in the GOM and similar migrating patterns south in the winter, I want to be optimistic that it can happen.