Lake Ontario Temps

[Gill-T]

As of Dec 13th, 46 degree water offshore of Sodus. NE winds been pushing the cooling surface water to the West. 

[Gill-T]

December 20 th reading showing 45 deg water off Sodus Pultneyville. I wonder if the alewife survey will show stronger in the central region this year?

[jeb1340]

I wonder what has a bigger impact. A warmer early winter? Early thaw? Or if it’s just total duration of warmer temps?

[Gill-T]

I think the answer is where does the foodweb set up at the plankton level. Currents, nutrients and oxygen levels at depths have to be in play. 

[GAMBLER]

3 hours ago, jeb1340 said:

I wonder what has a bigger impact. A warmer early winter? Early thaw? Or if it’s just total duration of warmer temps?

I ran years of temp data and compared it to the State of the Lake meetings trawl assessments and there were warm winters with great survival and warm winters with poor survival.  There were also cold winters with good survival and cold winter with bad survival.  What we all know is winters like 2014 and 2015 survival is horrible.  Those winters, we had issues with frazzle ice in our intake.  Schreksoff is the man and hopefully he chimes in.  

[Gill-T]

Agreed it can’t all be the weather. During  the last few decades the system has undergone huge upheaval with invasive species. The lakes are still settling things out. Is it the cold winter or the effect of an invasive shrimp species that negatively affect a year class of alewives?  

[GAMBLER]

24 minutes ago, Gill-T said:

Agreed it can’t all be the weather. During  the last few decades the system has undergone huge upheaval with invasive species. The lakes are still settling things out. Is it the cold winter or the effect of an invasive shrimp species that negatively affect a year class of alewives?  

I would think there are tons of factors.  Length of winter, health of YOY alewife going into winter, strength of the bottom of the food chain going into winter, predation and who knows what else!    

[ifishy]

there is likely a specific threshold for plankton growth where it can out pace predation.  its likely a combination of temp and photo period and nutrient load.  the longer it is not able to grow the longer the bait has to survive on its fat stores.  Temperature is a significant factor but its probably a higher temperature needed than we generally think about so a cold vs mild winter could easily be off set by a faster or shorter warm up and cool down.  

the longer the growing season the fatter and healthier the bait going into the cold and the shorter the non growing season the less time the bait has to go without food.  

[schreckstoff]

You all have perfectly described how I think, and what the data suggests, are the factors driving LO alewife year class strength.

 

 Warm early springs increase spawn timing and number of spawns which allows the most age-0 alewife to grow as big as possible by winter. Larger size going in to winter increases the probability they make it through to be counted by trawl following spring. Nutrients and larval predation help set a carrying capacity going into winter and then winter duration can have an effect, especially when populations are dense. But we don’t have those densities like we used to (late 70s- early 90s). This is why biologists and managers from that era talked so much about winter severity but you don’t hear that as often now. Now we think spring timing, nutrients, and predation have a stronger influence.