2006 Sag.Bay naturals and VHS.

[Walleye Express]

>>> <[email protected]> 03/12/2007 3:59 PM >>>

So, Dave.

Any more word on the 2006 Saginaw Bays natural walleye survival rates. And does the DNR plan on taking any eggs at all from the Tittabawassee this spring considering the VHS findings. Dan.

Dan.

The catch rate of Young-of-the-year walleyes in our trawling this past September was much lower than the last three years (which were all record numbers) but still represented a year class that was about average compared to most stocked years (for the long term average) before the recent surge the past three years. Alewives are still scarce in Lake Huron and we believe that the conditions are still optimal for very good reproductive success for walleye but as we also predicted that at some point, these other very strong year classes would begin to suppress newer walleye year class strength of subsequent years through competition and even cannibalism. This is a common phenomenon in walleye populations (a strong year class will suppress the following year class) thus its unusual to have two strong year classes in a row and three in a row (like we have) is almost unheard of. So the fact that the 2006 year class is not nearly as strong is not surprising and not particularly disturbing. Besides, there is still a 2006 year class there, and not out of line with the long term average despite the lack of stocking in 2006. The exciting news is that it now appears that the 2005 year class is much much stronger than we previously thought (compared to how it showed as young-of-the-year). It appears to be as much as twice as strong as the 2003 year class. This is based on catch rate of yearlings in our survey nets. Yearling catch rate is the best expression of year class strength because they have survived their first winter and the true (lasting) strength of the year class is usually set by then. It appears as if the 2005 year class enjoyed much better over-winter survival than the 2003 and 2004 year classes did. This very strong 2005 year class explains partly why everyone is still catching many many sublegal walleyes. The 2003s are fully legal size by now and the 2004s will be this summer too. The future continues to look very bright for Saginaw Bay walleyes sans the VHS issue.

As for walleye stocking in 2007 (this year), its all very much undecided at the moment. The final decision will probably be made this week. Because egg disinfection procedures for walleye eggs are unproven at present, there is a real possibility that no walleye egg collection or culture will take place in any state operated hatchery this year (in an effort to keep the disease out of our hatcheries). That decision hasn't been made yet, but its a real possibility. If that decision gets made (to not rear any walleye in 2007) that will be a decision only for this year and will again be revisited for future years once egg disinfection techniques are established for walleye. There's a good possibility that no walleye stocking will be recommended for Saginaw Bay in 2007 even if walleye rearing were to take place because of the three to four strong year classes currently present and because alewives continue to remain scarce. That decision is under advisement and we should have the final word here soon as well.

Check back with me in a week or two and I can tell you more then.