Striped Bass Regulatory Proposal: The Staff Report

[Marty Gingras]

Hi all,

You know the regulatory proposal but we are only just now releasing the Staff Report in support of the proposal.

The California Fish and Game Commission has received the Staff Report (and memo on-topic) that I have posted at the links below:

ftp://ftp.delta.dfg.ca.gov/Adult_Sturgeon_and_Striped_Bass/signed%20memo.pdf

ftp://ftp.delta.dfg.ca.gov/Adult_Sturgeon_and_Striped_Bass/SB%20Staff%20Report%2012-05-11.pdf

The Commission's receipt of these documents is on the 'Consent Calendar' at their December 15 (2011) meeting but discussion is scheduled for the Commission's February 2 (2012) meeting in Sacramento.

Thanks

Marty Gingras
BDR-IEP Program Manager
California Department of Fish and Game
Bay Delta Region
4001 North Wilson Way
Stockton, California 95205

Phone (209) 948-3702
FAX (209) 946-6355
email mgingras@dfg.ca.gov

[Frank Alessio]

Looks like The Black Bass is second on the Hit list...

[Tony Buzolich]

This recommendation is so focused on striped bass other causitive factors seem downplayed.

Three things that I did pick up on was the mention that in years past when striped bass populations were at their highest so were the populations of delta smelt, longfin smelt, splittail, etc. Newer causitive factors like water diversions didn't get mentioned.

It also was brought up about" TOTAL KEEP AND KILL" of striped bass like that which was done to the pike population in Lake Davis, and, the consideration of even putting a "BOUNTY" on striped bass so as to again totally keep and kill every striped bass in the system. The report did say that both of these last considerations would result in a "nuclear" result to the population, but the fact that it was even considered shows how drastict this department thinks to achieve it's goal.
TONY

[Marty Gingras]

Three things that I did pick up on was the mention that in years past when striped bass populations were at their highest so were the populations of delta smelt, longfin smelt, splittail, etc. Newer causitive factors like water diversions didn't get mentioned.

In addition to our use of time-series information throughout (i.e., addressing changes over time), under alternatives at page 23 this statement addresses (I believe) your concern:

"The decline of listed species occurred only after striped bass had been established in California for many decades and the SWP and CVP were substantially implemented, which, given the timing and rate of development (e.g., water, timber, agriculture, roads, industry, etc.) in California, suggests the species could co-exist in a future where the impact of development was effectively mitigated. Although some have argued that habitat restoration and mitigation is being implemented to the fullest extent of the law, the status of the listed species has not improved. Recovering the listed species is an extremely urgent matter that must be attempted using all feasible means."


It also was brought up about" TOTAL KEEP AND KILL" of striped bass like that which was done to the pike population in Lake Davis, and, the consideration of even putting a "BOUNTY" on striped bass so as to again totally keep and kill every striped bass in the system. The report did say that both of these last considerations would result in a "nuclear" result to the population, but the fact that it was even considered shows how drastict this department thinks to achieve it's goal.

This report speaks to listed-fish stakeholders as well as to striped bass stakeholders (I know that many are in both camps), and some stakeholders support 'nuclear' options.

[Darian]

Read the report while trying to stay awake (late night :| ). Hope these thoughts make sense....

The inclusion of potential alternatives (even tho I'm not sure I like 'em) does tend to show there's consideration of the possibility that the unexpected can happen.

The report appears to cover everything relative to requirements of the settlement agreement. What is evident is the uncertainty of achieving desired outcomes of this proposal based on the incomplete information included in the report. I know this observation is, perhaps, a bit over the top but it seems to me that the proposal amounts to a SWAG as a result. In recognition, it's difficult to study/report everything under the dual constraints of limited time and resources....

The urgent tone of the proposal makes me curious. If fish from many or all of the listed species are being maintained in conservation hatcheries, why the urgency :?: Are those populations in the Delta so low in numbers that they're in immediate danger of disappearing :?: Are they unable to live/spawn in captivity successfully :?: Isn't using a hatchery to support populations of listed species a form of mitigation as in the case of Salmon/Steelhead???

[Marty Gingras]

If fish from many or all of the listed species are being maintained in conservation hatcheries, why the urgency :?:

As the abundance of listed species declines, so too does genetic diversity and resiliency. Hatcheries are a far-from-ideal measure of last resort.


Are those populations in the Delta so low in numbers that they're in immediate danger of disappearing :?:

Yes.


Are they unable to live/spawn in captivity successfully :?:

See my first reply.


Isn't using a hatchery to support populations of listed species a form of mitigation as in the case of Salmon/Steelhead???

No.

[Darian]

Marty,.... DFG conducts a trawl survey of listed species, what happens to the fish caught by that method :?: If they're not to be used for the purpose of study's, are they counted and released or do they die :?:

When conducting a trawl survey for Striped Bass, how often are listed species captured as by-catch :?:

[Marty Gingras]

DFG conducts a trawl survey of listed species, what happens to the fish caught by that method :?: If they're not to be used for the purpose of study's, are they counted and released or do they die :?:

The take of federally-listed species during research in the delta --- even research intended to protect and recover the listed species --- is conducted under the terms of permits. I'm quite sure that's the same everywhere. Same for take of fish listed under CESA, except that DFG doesn't issue permits to ourselves. I'm quite sure that's the same everywhere. A lot of thought and effort goes into what amount to 'scientific collecting permits.'

For example: The permits that have controlled the studies I supervise have effectively necessitated a reduction in listed-species take, often via an adaptive management process. Those permits require protective handling and release of listed fish, unless the research requires something different. The permits also require weekly reporting of take.


When conducting a trawl survey for Striped Bass, how often are listed species captured as by-catch :?:

There are no striped bass-specific trawl surveys. The closest we come to that are the large-mesh nets and traps --- which don't take the listed smelts --- used by the striped bass population study to collect adult striped bass for tag-and-release. That population study rarely encounters green sturgeon or listed salmonids, in large part because we select times of the year, locations, and gear that avoids them.

[matt johnson]

Thanks Marty, for this post and the many others.....

I found it interesting that the data in the staff report documents that populations of winter and spring-run Chinook, and to some extent Delta smelt, were actually increasing or enjoying a period of relative abundance during the period 1999-2006.

I understand that Chinook salmon are typically 3-4 years of age when they return as adults.

Subtracting 3-4 years off each year class of winter and spring run Chinook from the early to mid 2000's puts the juveniles in perilous intersection with a relatively robust late 90's to early 2000's striped bass population?

And what was up with that off the charts return of fall run in 2002?

Don't need an answer, just an observation. Thanks! Matt

[Darian]

Interesting observations.... If I recall my reading on Salmon from, admittedly non-scientific literature, that male Salmon return in larger numbers and at a wider variance in ages than females. Smaller males are called jacks and return earlier (in their second/third years) and in large numbers in order to supplement those of the older males. Thus, assuring enough males to guarantee mates for successful spawning. If my understanding is correct, wouldn't the 3 - 4 year return cited for typical Salmon be an overstatement of age or does typical mean an average (or some other measure) :?: Of course, since not much is as it was when most of the literature I was reading from was written, maybe this return strategy has changed, too. :confused:

I note in the Staff Report that no mention of predation on other listed species or canabalism by Salmon/Steelhead is included in the report. Yet, it does occur. :-s

Well, enough of this for now. I'm still digesting this stuff.... :lol:

[matt johnson]

Interesting observations.... If I recall my reading on Salmon from, admittedly non-scientific literature, that male Salmon return in larger numbers and at a wider variance in ages than females. Smaller males are called jacks and return earlier (in their second/third years) and in large numbers in order to supplement those of the older males. Thus, assuring enough males to guarantee mates for successful spawning. If my understanding is correct, wouldn't the 3 - 4 year return cited for typical Salmon be an overstatement of age or does typical mean an average (or some other measure) :?:

Two year-olds, mostly jacks (males) and a few jills (females), typically make up only a small proportion of the spawning run for all four races of Chinook in the Valley. I have heard that two year-olds are commonly found in higher proportions in the Klamath Basin, but I don't have much experience with the Klamath....

Most of the Chinook age reconstruction in the Central Valley comes from coded wire tag recoveries. Coded wire tags are essentially a hatchery salmon's birth certificate. They age a salmon with certainty. Most of the coded wire tagged hatchery Chinook in the Central Valley come back at three to four years of age....

However, (there are few holes for round pegs in fisheries science!) the last two years there have been unusually high numbers of two year old salmon returning to the hatcheries. Go figure? This has been verified through coded wire tag analysis.

Age analysis of naturally produced Chinook in the Central Valley is currently in active data collection and analysis mode and is based on scale reading. I am unaware of any results so far....

[matt johnson]

I note in the Staff Report that no mention of predation on other listed species or canabalism by Salmon/Steelhead is included in the report. Yet, it does occur. :-s


Predation is a constant in the life of a baby salmon. Ever wonder why a female salmon lays a few thousand eggs? If they stuck around to gaurd their young instead of dying, predation might be a lesser variable. The heat is on as soon as those fry emerge from the gravel!

Addressing Darian's point: Consider winter-run Chinook fry for a moment.... The entire fry population emerges smack in the middle of crazy numbers of big resident rainbows, rainbows that would likely have smolted and got the hell out to the ocean if livin' weren't so easy in a temperature controlled environment.... But who knows if the Sac rainbows even eat winter-run fry?? No one is looking at that. (So far swinging fry patterns on the Sac has not been as fruitful as it was for me on the Yuba, but I don't get out much these days...)

The cool thing about predation is it makes survivors. What really galls me about some predation studies out there is the fact that they are using (out of necessity) hatchery smolts to conduct their studies. It may be that hatchery and wild smolts behave completely differently when faced with predators in the delta environment???

Here is a likely scenario of what is being done in some studies: A group of flabby "meat missles" that have been living on pellets in a concrete ditch with zero exposure to predation are driven to some location in the delta. The fish are then put to sleep and surgically implanted with a plastic coated tag about the size of a seedless green grape. After coming out of the dope and resting in a tub for awhile, the fish are released and their progress through the delta is monitored. Do such studies offer an accurate representation of the behavior of wild juvenile salmonids when dealing with predation ??? Maybe they do maybe they don't???

Predation is a fact of life as soon as a fry emerges from the gravel. We have engineered the hydrology and physical structure of the delta so that predators have an advantage. That is the problem with predation . Matt

[bart]

They have done some radio tagging latl;y.I don't know the extent of it,but will be asking questions.

[Darian]

Matt,.... Thanks for the additional info. Your description of the situation with hatchery reared fish confirmed the way I thought it might actually be. I had no idea that the implant would be so large.... :shock:

BTW, I've had some luck on the Feather on alevin patterns during January (if that's any help).... :D

[Darian]

Matt,.... If I understand correctly, The radio tags are implanted into hatchery reared fish which are then released in Old River. Stripers eat/digest the hatchery smolts, including the radio tag. :-k

when Stripers pass their waste, what happens to the radio tag :?: Is it expelled by the Bass to lay on the bottom :?: Or, does it remain in the Striper :?:

Thinking out loud here, it's not likely the latter as there would be such an accumulation of tags that it would eventually block the digestive system.... So, it has to be that there's a bunch of tags remaining on the bottom of the Delta. Otherwise, there'd be a bunch of stripers dying from Constipation.... :eek: :lol: Do the radio tags continue to transmit while down there :?: If they still transmit, DFG must recognize this situation as the position of the transmitter would be static. Is DFG able to use the information generated or is it useless :?: I'm really curious about this.... :-k

[Marty Gingras]

I've done a bunch of telemetry (adult Chinook; splittail; striped bass), my staff have done some recently (pikeminnow; striped bass; steelhead), and we understand what others are doing.


If I understand correctly, The radio tags are implanted into hatchery reared fish which are then released in Old River. Stripers eat/digest the hatchery smolts, including the radio tag. :-k

Tagged fish are being released at a number of locations. No doubt striped bass sometimes eat tagged fish, but finding tagged fish in the stomach of striped bass (or any predator) is very uncommon. All told, critters that are reasonably big, act like predatory fish, are fast-moving, and sometimes quickly travel a long distance eat a varying and sometimes large fraction of tagged smolt-like salmonids.

As a related aside: Young salmonids implanted with coded-wire-tags --- or just the CWTs from such fish --- are relatively commonly found in the guts of pikeminnow harvested as part of the bounty program on the Columbia. The program has access to a lot of harvested pikeminnow. Application of CWTs is benign compared to application of acoustic or radio tags.


when Stripers pass their waste, what happens to the radio tag :?: Is it expelled by the Bass to lay on the bottom :?: Or, does it remain in the Striper :?:

Whatever eats the tagged fish generally expels the tag after a period of time.


Do the radio tags continue to transmit while down there :?:

They are usually acoustic tags. They transmit until their battery dies, which is generally relatively quickly (e.g., weeks to a month or so) for tags in little fish. Tags applied to the big fish around here (e.g., sturgeon) are often designed to transmit for years.


If they still transmit, DFG must recognize this situation as the position of the transmitter would be static. Is DFG able to use the information generated or is it useless :?:

The researchers in all the studies I've been a part of and in local studies I've read about take this into account. Vogel does it really well.

[cyama]

From the report
"Although studies of striped bass predation show each of the listed species to constitute a relatively small part of the striped bass diet, and although the actual level of striped bass predation on these species is unknown and likely unknowable, the enormous volume of fish (up to 110 million pounds annually) consumed by striped bass and the widespread distribution of striped bass within the geographic range of the listed species indicate the impact of striped bass predation on the listed species could be substantial;"


Marty,

The report is admitting that predation of listed species is a small part of the diet of Striped bass and is basically unknown and unknowable. How can the DFG justify such a huge jump in the catchable limit of bass? You are going from 2 fish over 18" to up to 6 fish at 12". Twenty fish in some areas. Can these numbers be challenged? Is the DFG set on the regulation as written? In comparison this would be like raising the trout limit to 15 fish in some areas...

I must admit i am not an expert in the whole striped bass predation situation, but last year I remember that the situation in the Delta was that water could not be pumped down South due to conservation of the Delta Smelt. Over the past year huge amounts of water have been pumped down south, tons of smelt have been ground up and now the stripers are at fault? What happened is all I can say...


One other question

"the enormous volume of fish (up to 110 million pounds annually) consumed by striped bass and the widespread distribution of striped bass within the geographic range of the listed species indicate the impact of striped bass predation on the listed species could be substantial;"


Is the estimated 110 million pounds consumed by striped bass to include their diet while in the ocean? If so that number should be reduced substantially when discussing the predation in the Delta...

[Marty Gingras]

How can the DFG justify such a huge jump in the catchable limit of bass?

The Staff Report, including the references, describes the justification. The sort of paraphrase I could provide here wouldn't do it justice.


You are going from 2 fish over 18" to up to 6 fish at 12". Twenty fish in some areas. Can these numbers be challenged? Is the DFG set on the regulation as written?

The proposal we submitted to the Commission is just that. The Commission can accept, reject, or amend it. The Commission receives a lot of input from those who oppose proposed regulations, and --- by sending a FAX or email, in person at a meeting, or by making a phone call --- anyone can given input to the Commission challenging our proposal.


Over the past year huge amounts of water have been pumped down south, tons of smelt have been ground up and now the stripers are at fault?

Water operations cause indirect and direct adverse impacts on listed fish. The indirect impacts are notoriously hard to quantify and are no doubt important. The direct impacts (e.g., loss of entrained fish) are easier to quantify up to a point --- because of the massive amount of data developed at the salvage facilities --- and are no doubt important.

I am not a 'water apologist', but have to say this because it's true and will help the discussion: Water operations have changed a lot over the years and many people don't realize that relatively few (but important numbers to be sure) delta smelt and longfin smelt have been lost in recent years due to entrainment. For example: I believe less than 60 delta smelt were salvaged (that is, rescued rather than allowed to get to the pumps) this year, such that --- even loosely accounting for delta smelt too small to be salvaged and such --- probably more like less than 20 pounds of them have been lost into the CVP and SWP south-delta diversions this year.

The salvage information is here:

http://www.dfg.ca.gov/delta/apps/salvage/Default.aspx

Reports on salvage (and to an extent, 'loss') are here:

ftp://ftp.delta.dfg.ca.gov/salvage/Annual%20Salvage%20Reports/


Is the estimated 110 million pounds consumed by striped bass to include their diet while in the ocean? If so that number should be reduced substantially when discussing the predation in the Delta...

All the bioenergetics-based estimates of prior prey consumption we cite in the Staff Report are system-wide and w/o regard to prey species. That is, the estimates include prey taken in the ocean. It's that way because it was impossible to discern otherwise.

We recognize that only a fraction of what striped bass consume gets consumed in any particular region during any particular period.

The collective 'we' are working to develop methods to make region- and prey-species-specific estimates of what striped bass consume.

[Darian]

Marty,.... Could the low numbers of Smelt lost to entrainment at the pumps in recent years be due, at least in part, to their low population numbers overall :?: (I'm assuming at my peril that nothing has been done to upgrade the salvage process at the pumps that would account for this)

[Jgoding]

Another thing thing on smelt.... aren't they pretty fragile and would probably disitengrate pretty easily anyway passing through the pumps? It would seem you would never know they were there as they pretty much melt like butter for the most part and you would be lucky to salvage any.

This whole situation kind of pisses me off but I will give Marty kudos for actively participating. My personal opinion is stripers are getting the short end of the stick on this proposal and we really need to look at habitat, water quality issues, and maybe even hatchery practices if we really want to save our beloved fisheries.

I know water interests are important as well, but goddamn, we're not the well-spring for SoCal or agribusiness that wants to grow water intense crops or crops solely for export in arid regions.... it's not sustainable and they need to realize that and get over it really quick or invest money in other resources/technologies to get freshwater elsewhere. I gather from what is spent on hiring lawyers etc... and court costs it couldv'e been done already. And the peripheral canal..... really..... the whole idea and how it's being pushed into a possible reality is just disgusting.

[Marty Gingras]

Could the low numbers of Smelt lost to entrainment at the pumps in recent years be due, at least in part, to their low population numbers overall :?:

Yes. The Biological Opinion (basically, a permit from USFWS with conditions protective of delta smelt) accounts for that though, by varying allowable loss of delta smelt relative to the most-recent delta smelt abundance index.


Another thing thing on smelt.... aren't they pretty fragile and would probably disitengrate pretty easily anyway passing through the pumps?

Delta smelt are fragile. That's not an issue though, because there is no need to sample them downstream of the CVP and SWP south delta pumps. Salvage happens way upstream from the pumps and any fish that aren't salvaged are defined as lost.

[Jgoding]

Thanks Marty, wasn't exactly sure where the salvage occurred. I guess I always assumed it was at the pumps.

[bart]

Marty.Where upstream are smelt salvaged and by what method?

[Marty Gingras]

Marty.Where upstream are smelt salvaged and by what method?

The salvage (salvage is a good thing) of fish from water diverted by USBR happens in the Tracy Fish Facility, which is near Clifton Court Forebay at the confluence of Old River and West Canal.

The salvage of fish from water diverted by DWR happens in the Skinner Fish Facility at (basically) Clifton Court Forebay. The draft report here explains a lot about salvage at the Skinner Fish Facility:

ftp://ftp.delta.dfg.ca.gov/Adult_Sturgeon_and_Striped_Bass/Draft%20Skinner%20Fish%20Facility%20POD%20Report%2 0-%20jmorinaka%2011-%E2%80%A6.pdf

Salvage at the Tracy Fish Facility happens very much like salvage at the Skinner Fish Facility. Here is a link to a lot of information about the Tracy Fish Facility:

http://www.usbr.gov/pmts/tech_services/tracy_research/

[Darian]

While reading the draft report on the Skinner facility, it suddenly dawned on me that the Trash rack has some very large openings in it. This is a quote taken from the report:

"Large fish and debris are prevented from entering the facility through the trash rack’s vertical 5.1 cm wide openings."

If I'm calculating correctly, a 5.1 meter wide opening equals approximately 199". Also, this rack spans the entire width f the channel and, I assume, extends from top to bottom. How do the openings prevent large fish passage :?: Only the largest Sturgeon (....and perhaps Humphrey the wayward whale) would not be able to go through an opening that wide. Is there more to the description of the Trash Rack.... :confused:

[cyama]

Marty,

Thanks for taking time to answer my questions and provide information! I must admit you have a very tough job! I have seen some of the work being done by several fisheries biologists on various projects and they all work hard to make it all work. One of the best sites I have visited is the Livingstone Hatchery at the base of Shasta Dam. They have a secret stash of Delta Smelt if the system crashes. Lets just hope we don't have to use that stash.... Peace

[Marty Gingras]

"Large fish and debris are prevented from entering the facility through the trash rack’s vertical 5.1 cm wide openings."

If I'm calculating correctly, a 5.1 meter wide opening equals approximately 199". Also, this rack spans the entire width f the channel and, I assume, extends from top to bottom. How do the openings prevent large fish passage :?:

The trash rack openings are small. You swapped units from centimeters to meters w/o moving the decimal point.

[Darian]

Senior moment.... #-o #-o Ed,.... I need a day or two with Duke....

[bart]

Delta smelt are fragile. That's not an issue though, because there is no need to sample them downstream of the CVP and SWP south delta pumps. Salvage happens way upstream from the pumps and any fish that aren't salvaged are defined as lost.

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Last edited by Marty Gingras; Yesterday at 03:27 PM.
The impression from the above quote is that there is an upstream collection going on.The skinner facility and fed facility are very close to each other and the louvers are appox.2" wide and use a vibration type water to channel them to the collection area.I thought you meant there was some point i didn't know about.The chance for survival from transport to release on sherman island is almost nil.I don't know of any down strea survey that tells about survival from that point

[Marty Gingras]

The chance for survival from transport to release on sherman island is almost nil.I don't know of any down strea survey that tells about survival from that point

What makes you say that? That used to be the common wisdom among biologists and the public, but really isn't anymore with biologists who work on it. We have relatively-recent data --- from the so-called CHTR studies conducted around 2005 --- that pretty-strongly suggests otherwise.


I don't know of any down strea survey that tells about survival from that point

Post-release survival of salvaged fish is an important gap in knowledge. It's a very difficult thing to quantify. Common-sense things (e.g., more release sites) are being done in hopes of improving it. Studies are being considered to evaluate it.

[Darian]

Bart,.... Could you clarify the following partial quote:

"....use a vibration type water...."

I'm not clear on what that is. In the context used, do you mean that the moving water is difficult for smaller fish like Smelt to maintain position in or something else :?:

[bart]

Darian.The angle of the louvers creates big vibrations that cause the fish to be channeld into the pipe that goes to the recovery area.Maybe next spring we can set up a tour of skinner.I have lead 3 tours over the years.

[Darian]

Bart,.... A tour is a great idea. Let me know when you can set it up. :D

[bart]

May is a good time for a tour.Thats the hight of the spawning time.I'll look into it.

[Justin]

Marty,

A Northern California Newspaper recently(I believe Friday?) ran an article on the recent up spike in Delta Smelt populations. It quoted you as citing the increase of water from last years rain fall as the contributing factor. With that in mind, has the DFG pursued stopping or lessening the export of water(again) in a law suit? If they have not, why? And what is the DFG plan for stopping water loss. You yourself understand the impact of water to our fisheries. My apologies if you have answered this somewhere else.

Thanks,

Justin

[Marty Gingras]

Marty,

A Northern California Newspaper recently(I believe Friday?) ran an article on the recent up spike in Delta Smelt populations. It quoted you as citing the increase of water from last years rain fall as the contributing factor. With that in mind, has the DFG pursued stopping or lessening the export of water(again) in a law suit? If they have not, why? And what is the DFG plan for stopping water loss. You yourself understand the impact of water to our fisheries. My apologies if you have answered this somewhere else.

Thanks,

Justin

Potential litigation, litigation tactics, and litigation strategy are things that staff like me don't comment on because those are policy matters and because we aren't attorneys.

When managing listed fish being taken by water diversions, DFG operates under the California Endangered Species Act (CESA).

If the fish is listed under both CESA and the federal ESA (FESA) --- like Delta smelt --- then under certain circumstances DFG can address water through what's called a Consistency Determination (CD). Here is a link explaining CDs:

http://www.dfg.ca.gov/habcon/cesa/incidental/consist_determine.html

DFG has issued a CD regarding Delta smelt and operation of the State Water Project.

If the fish is listed only under CESA --- like longfin smelt --- then under certain circumstances DFG can address water through an Incidental Take Permit (ITP). Here is a link explaining ITPs:

http://www.dfg.ca.gov/habcon/cesa/incidental/incid_perm_proced.html

Here is a link to an ITP for longfin smelt:

http://www.dfg.ca.gov/delta/data/longfinsmelt/documents/LongfinSmeltIncidentalTakePermitNo.2081-2009-001-03.asp

Managing non-listed fish being taken by water diversions is relatively complicated and I'd have to do some research to give a reasonably comprehensive explanation. I've seen (and done) it by way of Section 1600 of the Fish and Game Code. See here for that law:

http://www.leginfo.ca.gov/cgi-bin/waisgate?WAISdocID=95728122563+1+0+0&WAISaction=retrieve

I think the upshot of the above is this: The legislature has given DFG only certain authority to restrict the export of water, using that authority is not a trivial exercise, and DFG commonly uses that authority.