**Delta smelt Risk Assessment Matrix (DSRAM) June 22, 2004**

  ------------ -------------- ------------- -------------- ----------- ----------- --------- ---------- ----------
  **Tools for  **December**   **January**   **February**   **March**   **April**   **May**   **June**   **July**
  Change** (7)                                                                                          

  Export       X              X             X              X           X           X         X          X
  reduction at                                                                                          
  one or both                                                                                           
  facilities                                                                                            

  Change in                                                                        X         X          X
  barrier                                                                                               
  operations                                                                                            

  Change in                                                X           X           X         X          X
  San Joaquin                                                                                           
  River flows                                                                                           

  Change                                                                           X         X          
  position of                                                                                           
  cross                                                                                                 
  channel                                                                                               
  gates                                                                                                 
  ------------ -------------- ------------- -------------- ----------- ----------- --------- ---------- ----------

Delta Smelt Risk Assessment Matrix Footnotes

1.  The Recovery index is calculated from a subset of the September and
    October Fall Midwater Trawl sampling
    (<http://www.delta.dfg.ca.gov/>). The number in the matrix, 74, is
    the median value for the 1980-2002 Recovery Index (Figure 1)

2.  The temperature range of 12 to 18 degrees Celsius is the range in
    which most successful delta smelt spawning occurs. This has been
    analyzed by using observed cohorts entering the 20-mm Survey length
    frequency graphs (1996-02). Cohorts were defined by having a
    noticeable peak or signal and occurring over three or more surveys
    during the rearing season. Temperature data from DWR's CDEC web site
    was compiled using three stations representing the south Delta
    (Mossdale), confluence (Antioch), and north Delta (Rio Vista).
    Spawning dates for each cohort was back-calculated by applying an
    average daily growth rate (wild fish) of 0.45 mm/day (Bennett, DFG
    pers. comm.) and egg incubation period of 8-14 days
    (Baskerville-Bridges, Lindberg pers. comm.)(Mager et al. 2004) from
    the median value of the analyzed cohort. Each spawning event was
    then plotted against temperature over time (Figure 2.1). While
    spawning does occur outside of the 12-18 degree range, larval
    survival is most likely reduced when temperatures are either below
    (DFG pers. comm.) or above this range (Baskerville-Bridges & DFG
    pers. comm.).

> Critical thermal maxima for delta smelt was reached at 25.4 degrees
> Celsius in the laboratory (Swanson et al., 2000); and at temperatures
> above 25.6 degrees Celsius smelt are no longer found in the delta
> (DFG, pers. comm.).
>
> Websites for the temperature data:
> <http://cdec.water.ca.gov/cgi-progs/queryF?MSD>
>
> <http://cdec.water.ca.gov/cgi-progs/queryF?ANH>
>
> <http://cdec.water.ca.gov/cgi-progs/queryF?RIV>
>
> Mager RC, Doroshov SI, Van Eenennaam JP, and Brown RL. 2004. Early
> Life Stages of Delta Smelt. American Fisheries Society Symposium
> 39:169-180.
>
> Swanson C, Reid T, Young PS, and Cech JJ. 2000. Comparative
> environmental tolerances of threatened delta smelt (*Hypomesus
> transpacificus*) and introduced Wakasagi (*H. nipponensis*) in an
> altered California estuary. Oecologia 123:384-390.
>
> 3 Figure 3: The working hypothesis for delta smelt is that spawning
> only occurs when temperatures are suitable during the winter and
> spring. In years with few days having suitable spawning temperatures,
> the spawning \"window\" is limited, so the species produces fewer
> cohorts of young smelt. Few cohorts increases the risk that mortality
> sources such as entrainment may have population level effects. The
> figures below were used to help define years when there were
> relatively days with suitable temperatures. For April 15 and May 1,
> the figures show the cumulative spawning days for each year during
> 1984-2002. The cumulative spawning days for each year were calculated
> based on the number of days that the mean water temperature for three
> Delta stations (Antioch; Mossdale and Rio Vista) was in the 12 - 18 C
> range starting on February 1. The results are plotted in terms of the
> ranks to identify the lower quartile. In other words, years in the
> lower quartile represent examples of years with relatively few
> spawning days.

4.  The adult spawning stage is determined by the Spring Kodiak Trawl
    and/or fish salvaged at the pumping facilities
    (http://www.delta.dfg.ca.gov/). A stage greater than or equal to 4
    indicates female delta smelt are ripe and ready to spawn or have
    already spawned (Mager 1996).

> Mager RC. 1996. Gametogenesis, Reproduction and Artificial Propogation
> of Delta Smelt, *Hypomesus transpacificus.* \[Dissertation\] Davis:
> University of California, Davis. 115 pages. Published.

5.  The spring kodiak trawl will be used to help generally determine the
    distribution of adult smelt. However, since the spring kodiak trawl
    is not intended to be a survey for abundance or distributions, no
    definitive trigger for concern can be determined at this time.

> Juveniles (March-July) -- distribution of juvenile delta smelt where
> the centroid is located upstream (negative) or downstream (positive)
> of the Sacramento-San Joaquin River confluence (Figure 5.1). The 20-mm
> Survey (or Summer Townet Survey) centroid is calculated by multiplying
> the observed delta smelt station CPUE (fish/10,000 m3) by a distance
> parameter in km from the confluence. The summed result (summed over a
> survey) is divided by the survey CPUE which gives the survey centroid
> position (Figure5.2)
>
> Low juvenile abundance will also be a trigger. Abundance (total
> cumulative count) will be monitored throughout the sampling season
> with low values based upon median values of historic cumulative 20-mm
> Survey catch (1995-2003). Each survey within a season has a median
> value associated with it and when catch is equal to or below that
> value, concern is high (Table 5).
>
> 6 Salvage trigger: the salvage trigger for December through March is
> determined by calculating the ratio of adult salvage to the fall MWT
> index. This ratio will increase as fish are salvaged during the winter
> months. If the ratio exceeds the median of what was observed during
> December-March 1980-2002, then the trigger was met (see Figure 6 for
> more explanation of the calculation)
>
> During May and June, if delta smelt salvage at the salvage facilities
> is greater than zero, then the working group will meet. This is
> because May and June are the peak of smelt salvage and salvage
> densities cannot be predicted. Therefore, during these two months, the
> smelt working group will meet proactively to protect these fish by
> looking at relevant information such as salvage, delta temperatures,
> delta hydrology and smelt distributions.
>
> 7 The tools for change are actions that the working group can
> recommend to the DAT and WOMT group to help protect delta smelt.
> Exports may be reduced at one or both of the south delta export
> facilities and a proposed duration of the reduction would be
> recommended by the working group. Export reductions and changes in San
> Joaquin River flows may be covered by B(2) or EWA assets. Details of
> past fish actions can be found at the Calfed Ops website:
> [http://wwwoco.water.ca.gov/calfedops/index.html]{.underline};
> \>Operations \[year\]

**Figure 1**

![](media/image1.wmf){width="6.4992125984251965in"
height="5.504724409448819in"}

Points are labeled with the year representing the recovery index.

The winter salvage is for this analysis starts in December of the
recovery index year

and carries through March of the following year.

**Figure 2.1**. Successful delta smelt spawning periods (black bars) and
start and end of spawning season (yellow bars) determined by the 20-mm
Survey catch results (1996-2002). Temperature data (^o^C) was compiled
from CDEC using mean daily temperatures from the south Delta (Mossdale),
north Delta (Rio Vista), and confluence (Antioch).

> ![](media/image2.wmf){width="6.0in"
> height="3.0in"}![](media/image3.wmf){width="6.0in"
> height="2.958267716535433in"}![](media/image4.wmf){width="6.0in"
> height="2.986220472440945in"}

**Figure 2.1 cont.**

> ![](media/image5.wmf){width="6.0in"
> height="2.9791338582677165in"}![](media/image6.wmf){width="6.0in"
> height="3.0in"}![](media/image7.wmf){width="6.0in" height="3.0in"}

**Figure 2.1 cont.**

> ![](media/image8.wmf){width="6.010416666666667in"
> height="3.0520833333333335in"}

**Figure 3**

![](media/image9.wmf){width="6.270833333333333in"
height="3.9791666666666665in"}

**Figure 3 continued**![](media/image10.wmf){width="6.28125in"
height="3.9895833333333335in"}

**Figure 5.1**. A 20-mm Survey delta smelt bubble plot map with
calculated centroid position from the confluence of Sacramento-San
Joaquin Rivers with one standard deviation.

![](media/image11.wmf){width="6.0in" height="7.857638888888889in"}

**Figure 5.2**. Historic juvenile centroid position (20-mm Survey) with
one standard deviation.

![](media/image12.wmf){width="6.0in" height="3.5625in"}

**Table 5.** Lower quartile values of cumulative catch from the 20-mm
Survey. When cumulative catch per survey during a season is at or below
the calculated value, concern is high.

  ---------- -------- -------- -------- -------- -------- -------- -------- --------
             survey 1 survey 2 survey 3 survey 4 survey 5 survey 6 survey 7 survey 8

  lower      12       40       144      188      346      500      924      1019
  quartile                                                                  
  ---------- -------- -------- -------- -------- -------- -------- -------- --------

**Figure 6**

The objective is to quantify a level of concern for adult delta smelt
during the winter, that is based upon not only the number of fish
salvaged but also accounts for the overall abundance of smelt. Whatever
quantifier we select should reflect that when the abundance is low and
salvage is high concern is high and conversely, when abundance is high
and salvage is low that concern is low.

Below is a Quantile plot of the ratio of winter salvage to MWT index
(ln(winter salvage/MWT index)). Winter salvage is defined as the total
salvage from December through March. In the figure below, the size of
the bubbles is proportional to the log of the fall midwater trawl just
to give some indication of relative abundance. The resulting quartiles
of the ratio are as follows: 25% =: 2.950; 50%= 3.575; 75% 5.029.

If we were to use this approach to calculate winter concern levels and
use the median value, then all years above the 1999 point in the graph
would have been years of concern. In other words, these are the years in
which we may have recommended some protection. Comparing it to the
protection afforded adult delta smelt in the winter by the 1995
Biological Opinion ("red light" was, or would have been reached in the
following winters of 1980, 1981, 1982, 1984 and 1999) .

If the median was selected was selected as the measure of concern would
be calculated by:

concern level = anti ln(3.575)\* MWT index

![](media/image13.wmf){width="6.5in" height="4.605555555555555in"}

The goal for the DSRAM is to avoid the upper quartile of the above
graph, in general, to avoid high salvage events when the MWT index is
low. Actions would be taken prior to salvage events and ideally, high
salvage events would not occur.