Striped bass...

[Marty Gingras]

Have any dietary studies been done based on the size of the specimen being collected? Or have they simply been done based on the species as a whole?

The dietary studies I'm familiar with have all collected the data necessary to identify the fish eaten by striped bass of a particular size, but only most of the studies have also documented the size of prey. Due to rapid digestion of prey, it's actually quite tough (read, expensive) to get accurate lengths of prey items.

...was any of this taken into consideration in developing the proposed changes...

It was indeed.

W/regard to the proposed possession limits and the safe-eating guidelines, there are many different ways to think about our proposal. Here are a few:

(1) Due to striped bass demographics, the proposal would have the effect of allowing people to limit on small fish rather than large fish and --- because small fish have somewhat lower Mercury concentrations and relatively small mass --- those small-fish limits are safer than large-fish limits;

(2) the present bag and possession limits allow people to eat ~730 striped bass per year, yet you don't hear about people doing that;

(3) white sturgeon and striped bass have similar Mercury concentrations, even though a white sturgeon limit likely has much more Mercury (due to fish size) than the proposed striped bass limit.

[Darian]

Thanks for the response, Marty. I guess the consideration reflected is the opposite of what I thought it might be....

Would you say that the reason you don't hear about people eating the amount of Stripers possible in a given year is due to catch & release practices or just that nobody has actually checked on it

[ssy]

The dietary studies I'm familiar with have all collected the data necessary to identify the fish eaten by striped bass of a particular size, but only most of the studies have also documented the size of prey. Due to rapid digestion of prey, it's actually quite tough (read, expensive) to get accurate lengths of prey items.



It was indeed.

W/regard to the proposed possession limits and the safe-eating guidelines, there are many different ways to think about our proposal. Here are a few:

(1) Due to striped bass demographics, the proposal would have the effect of allowing people to limit on small fish rather than large fish and --- because small fish have somewhat lower Mercury concentrations and relatively small mass --- those small-fish limits are safer than large-fish limits;

(2) the present bag and possession limits allow people to eat ~730 striped bass per year, yet you don't hear about people doing that;

(3) white sturgeon and striped bass have similar Mercury concentrations, even though a white sturgeon limit likely has much more Mercury (due to fish size) than the proposed striped bass limit.

(1) Nice way of sugar-coating it!

[Marty Gingras]

Would you say that the reason you don't hear about people eating the amount of Stripers possible in a given year is due to catch & release practices or just that nobody has actually checked on it

From our creel data, the population of successful striped bass anglers are on average taking home less than the daily bag limit and releasing a lot of striped bass. That said, some may take limits frequently and some may eat quite a lot of striped bass.

I've never found any sign of a study about the eating habits of local striped bass anglers (or any anglers for that matter). It could be done, but would be expensive and pretty challenging.

[Darian]

Hi Marty,.... Just so you won't think we were giving you some time off for the holidays , I have a question related to invasives. How much impact, if any, has the unusually large volume of hyacinth had on the low end of the food chain in the delta and on food sources for the Delta/Longfin Smelt It must be part of the reason some parts of the Delta waters are so clear....

A follow-up on the above question is, what impact, if any, on the low end food chain has spraying to control hyacinth had on food sources for the same species

[Marty Gingras]

Hi Marty,.... Just so you won't think we were giving you some time off for the holidays

No problem at all!

How much impact, if any, has the unusually large volume of hyacinth had on the low end of the food chain in the delta and on food sources for the Delta/Longfin Smelt It must be part of the reason some parts of the Delta waters are so clear....

Since 2003 at least, discussion of exotic plants impacting fish has been about Egeria densa (Brazilian waterweed) rather hyacinth. Egeria is thought to have been a major part of the observed increase in water clarity.

A follow-up on the above question is, what impact, if any, on the low end food chain has spraying to control hyacinth had on food sources for the same species

I looked into this a while back and didn't find much information. The science is done by Department of Boating and Waterways. I can't do the topic justice here now, but there are a few threads about weed control on Blanton's Board, the following being (as I recall) the most fact-based:

http://www.danblanton.com/viewmessage.php?id=153787

Current emphasis on food for delta smelt is focused on the low-salinity zone (aka X2) during Fall. Research is on-going actually and is urgent, because one of the RPAs in the OCAP BO for delta smelt requires X2 to be farther downstream under certain circumstances and the rationale is (in part, basically) that delta smelt growth and survival is better when X2 is relatively far downstream during Fall.

[Darian]

Hmmm,.... Is X2 (Low salinity zone) where Smelt spend the majority of the year in the bays/Delta

Thinking out loud here.... I suppose the study of Smelt food sources in the fall is more reflective of impacts on food sources in X2 of low water (due to reduced input flows) than the rest of the year.... ( )

But, until it rains in the fall the only solution to moving X2 downstream appears to be increased releases from upstream storage. Do the upstream releases of water for Salmon spawning help or hinder the movement of X2 in favor of the Smelt or are there some timing issues

The more I think about this stuff, the more I realize how complex the overall relationships really are....

[ycflyfisher]

Marty,

Did the multiagency task force ever complete the study that was being conducted on the POD? If so is it available for public review? If not, is there anything more recent that the "Progress Report" from 2008 available?

[Marty Gingras]

Marty,

Did the multiagency task force ever complete the study that was being conducted on the POD? If so is it available for public review? If not, is there anything more recent that the "Progress Report" from 2008 available?

The POD investigations are still going on. Here is the web site:

http://www.water.ca.gov/iep/pod/

Here is a link to the latest synthesis of findings:

http://www.water.ca.gov/iep/pod/synt..._workplans.cfm

[Marty Gingras]

Is X2 (Low salinity zone) where Smelt spend the majority of the year in the bays/Delta

Sort of. Here are 'interactive' maps:

http://www.dfg.ca.gov/delta/projects.asp?ProjectID=20mm

http://www.dfg.ca.gov/delta/projects.asp?ProjectID=SLS

http://www.dfg.ca.gov/delta/projects.asp?ProjectID=SKT

http://www.dfg.ca.gov/delta/projects...ojectID=TOWNET

Do the upstream releases of water for Salmon spawning help or hinder the movement of X2 in favor of the Smelt or are there some timing issues

I can't do that question justice. Suffice to say that there are plans afoot to (sort of) consolidate the NMFS and USFWS OCAP Biological Opinions so that interactions can be better addressed.

The more I think about this stuff, the more I realize how complex the overall relationships really are....

I do believe that ours is the most-complicated system in the country where major efforts are underway to understand and improve things.