rf „.- . -.., 

p.1 

5.2.4 Rockfishes 

a) 

b) 

c 

CD 

CO c 

CD 

50 

40 

30 

CD 

"53 

E 

1 

o 

$ 

c 

CO 

CO 

E 

20 

101 

Morro Bay Area: KGB rockfish complex 

PSMFC PacFIN Groundfish Landings (all gear types) 

70 -

_* 60 

w idln$ 

c 

« 40 -

c 30 -

I 20 

0 

10 -

0 - , • — i — 

,

T

;-:H 

DS. carnatus 

OS. chrysomelas 

US. a tro virens 

1 — 

;Pr!

:-

1 

: e.;.'2v-*L' 

Year 

KGB rockfish complex (Sebastes spp. V_De/V_D_) 

^_Vr^V"^f- '^ **"• \"\*&mHmJ*f*mmm • -^>\' 

i 1 1 1 1 1 1 r 

78 80 82 84 

1 — 1 — \ 1 1— 1 1—1—1—1—1—1— 1 r 

86 88 90 92 94 96 98 

Plant Start-up 

Year 

Figure 5.2.4-7. Yearly abundance of KGB rockfish complex measured by two independent 

methods: a) Commercial fishery landings of adults from Morro Bay area and, b) Mean number 

of adults and YOY observed per 50-meter subtidal benthic transect in the DCPP RWMP 

South Control area. Spline smoothing algorithm used to fit curve through points. 

TENERA E9-055.0 5-183 Final 316(b) Demonstration 

March 1,2000 
P.2 

5.2.4 Rockfishes 

^^ 

UJ 

CO 

T_ 

+ 

E 

% 

J > 

</> 

cu 

Q 

CO 

CO 

2 

0.25 T 

0.24 -

0.23 ~ 

0.21 T 

0.20 -

0.19 T 

0.18 -

0.17 -

0.16 -

0.15 -

0.14 -

0.13 -

0.12 -

0.11 -

0.10 -

0.09 -

0.08 -

0.07 -

0.06 -

0.05 -

0.04 -

0.03 -

0.02 1 

0.01 -

0.00 -

• designatessurve 

•nirimt 

Blue rockfish complex 

(Sebastes spp. V / S. mystinus) 

I iU..i.*iiL V)Y(Tn .rnn?mT il i. ) || .k.lti»)^_ M . 1 m , , t • » 

|o|N| D | J |F|M|A|M|J | J|A|S|O|N|D|J|F|M|A|M|J|J|A|S|O|N|O|J|F|M|A|M| J j 

| isee | iss7 | im e | isos | 

Survey Date 

y with density =0 , 

Figure 5.2.4-8. Weekly mean larval density (#/m3 + 1 S.E.) at the DCPP intake. 

TENERA E9-055.0 5-184 Final 316(b) Demonstration 

March 1.2000 
m 

z 

m 

m 

o in 

cn 

CO 

O l 

3 

22. 

w 

£• g> 

11 

- »• * 

N ) CO 

o s-. 

o o 

O 3 

Blue rockfish complex (Sebastes spp. V & S. mystinus) 

CO 

E 

0.88 

0.77 

0.66 

0.55 

0.44 

0.33 

0.22 

0.11 

0.00 

Depth Contours 

•" 20 meters 

• 40 meters 

•BB B 60 meters 

Point Buchon 

DCPP Intake 

Point San Luis 

Jul. 21,"97 Aug. 25,'97 Sep. 29,'97 Oct. 20,'97 Nov. 17,'97 Dec. 10,'97 

Figure 5.2.4-9a. Mean larval density (#/m5) collected in the DCPP study grid cells and at the entrainment sampling location. 

Ol 

R> 

7) 

o 

o 

X 

21 

(A 

3" 

O ' 

CA 

TJ 

CO 
m 

z 

m 

m 

co 

6 

cn 

Ol 

b 

oo 

O) 

3 

21 

co 

.2 

"cr 

2 O 

• ^* 

ro co 

o « 

o o 

o 3 

Blue rockfish complex (Sebastes spp. V & S. mystinus) 

CO 

E 

0.88 

0.77 

0.66 

0.55 

0.44 

0.33 

0.22 

0.11 

0.00 

Depth Contours 

20 meters 

— 40 meters 

mmmm 60 meters 

Point Buchon 

DCPP Intake 

Point San Luis 

Jan. 22, '98 Feb. 26, '98 Mar. 18, '98 Apr. 15, '98 May 18, '98 Jun. 8, '98 

Figure 5.2.4-9b (continued). Mean larval density (#/m3) collected in the DCPP study grid cells and at the entrainment sampling location. 

cn 
/ 

m 

z 

m 

m 

CO 

• o 

Ol 

Ul 

o 

CD 

3 

ffl. 

CO 

w g 

§1 

- A CO 

ro co 

o -t. o o 

O 3 

Blue rockfish complex (Sebastes spp. V & S. mystinus) 

CD 

E 

0.88 

0.77 

0.66 

0.55 

0.44 

0.33 

0.22 

0.11 

0.00 

Depth Contours 

!•• 20 meters 

- ^ — 40 meters 

M B M 60 meters 

Point Buchon 

DCPP Intake 

Point San Luis 

Jul. 20,'98 Aug. 25, '98 Sep. 15,'98 Oct. 5,'98 Nov 10,'98 Dec. 8,'98 

Figure 5.2.4-9c (continued). Mean larval density (#/m3) collected in the DCPP study grid cells and at the entrainment sampling location. 
m 

z 

m 

m 

CO 

o 

cn 

Ol 

CO 00 

3 

92. 

co 

a> 

"c? 

- * CO 

• ^* 

ro co O =: o o 

O 3 

Blue rockfish complex 

(Sebastes spp. V & S. mystinus) 

CO 

0.88 

0.77 

0.66 

0.55 

0.44 

0.33 

0.22 

0.11 

0.00 

Depth Contours 

20 meters 

— — 40 meters 

H M 60 meters 

Point Buchon 

DCPP Intake 

Point San Luis 

Jan. 11, '99 Feb. 2, '99 Mar. 16, '99 Apr. 13, '99 May 23, '99 Jun 22, '99 

Figure 5.2.4-9d (continued). Mean larval density (#/m3) collected in the DCPP study grid cells and at the entrainment sampling location. 

cn 

KJ 

Ti 

o 

o 

7V 

3 1 

CA 

3 * 

CD. 

CO 
5.2.4 Rockfishes 

P.7 

CU o 

c 

g 

o 

>. 

u 

c 

cu 

3 

CT 

0 

C 

CU 

cu 

a . 

Blue rockfish complex (Sebastes spp. V / S. mystinus) 

N= 2,407 

nJMedian 

I 

2 . 1 3 . 6 4.1 

Length Category (mm) 

i • i • r-' i ' i ' r- - ' i ' i ' i i i r~ 

O 2 A e S 1 0 1 2 1 4 1 6 «"•»• • 

Estimated age (days) 

Figure 5.2.4-10. Length frequency of all measured larval fish collected in the entrainment 

samples. Minimum, median, mean, maximum, and central 98% ofthe larval lengths are noted. 

X-axis scale is not continuous at larger lengths. 

TENERA E9-055.0 5-189 Final 316(b) Demonstration 

March 1,2000 
P.8 

5.2.4 Rockfishes 

15" 

1 0 ' 

CD 

O 

C

 5-I 

CO 

3 

O 

o 

O 

Blue rockfish complex (Sebastes spp. V / S. mystinus) 

Entrainment: N=443 

Mediarfrvlean 

Min 

1 % 

-tfU^ L 

99% 

" 15-

c 

CD 

3 

CT 

CD 

"- 10" 

c 

CD 

O 

— Min 

CD 5 — 

1.9 2.4 2.9 3.4 3.9 

Grid: N=2,159 

MedianMean 

Max 

4.4 4.9 *° ^ 

1% 

..llll 

99% 

hi 

Max 

PPP^ ^ 

1.9 2.4 2.9 3.4 3.9 4.4 

Length Category (mm) 

' T TTT 

4.9 <o** 

Figure 5.2.4-11. Length frequency of measured fish from entrainment surveys that paired with 

grid surveys (both years combined). Minimum, median, mean, maximum, and central 98% ofthe 

larval lengths are noted. X-axis scale is not continuous at larger lengths. 

TENERA E9-055.0 5-190 Final 316(b) Demonstration 

March 1,2000 
P.9 

5.2.4 Rockfishes 

<^«* UJ 

CO 

1 

+ 

% • • 

3 E, 

2? 

CO 

c CD 

Q 

CO 

CD 

2 

0.12 — 

o.n -E 

0.10 ~E 

o.os-E 

: 

0.08 — 

: 0.07 — 

. 0.O6-Z 

0.05 — 

- 0.04 — 

0.03 — 

0.02 ~i 

0.01 — 

o.oo—-

i 

Blue rockfish complex (Sebastes spp. V / S. mystinus) 

I i: ."..." 

J 

I

 J I 

I 

I I i i i i i i 

1990 1991 1992 1993 1994 1995 1996 1997 

Year 

i 

i 

1998 

Figure 5.2.4-12. Annual mean density +/- 2 standard errors (vertical lines) and grand mean 

density for all years combined (horizontal line) for the Intake Cove surface plankton tows. The 

annual mean densities are based on seven consecutive months ofdata (December through June) 

except for 1990, which had only five months (February through June). 

TENERA E9-055.0 5-191 Final 316(b) Demonstration 

March 1,2000 
P.10 

5.2.4 Rockfishes 

Blue rockfish complex (Sebastes spp. V/S. mystinus) - mean duration 

Analysis Period 3: Jul 1997-Jun 1998 

R» atonoshor* 

90% Cl. 

Estimate 

Pw = 0.00338 

Pu = 0.00095510.0700 

3 8 x 

e o s k m 

4 0 x 

Slz a of Ropulatlon Ralattva to Study Orld 

Equivalent Distanoa Alonaahor e 

Blue rockfish complex (Sebastes spp. V/S. mystinus) - mean duration 

Analysis Period 4: Jul 1998-Jun 1999 

90% Cl. 

ax 

BT Km 

10x 1 Sx 

174 k m 26 1 

2 0 x 

3 4 7 k m 

2 6 x 30 x 30 x 40 x 

4 3 4 k m 62 1 k m SOS k m 6B6 k m 

Slz a of Ropulatlon Relative to Study Orld 

Equivalent Dlatanoa Alongahor a 

Figure 5.2.4-13a. Total annual entrainment mortality (/£ ) and 90% confidence interval (CI.) as 

a function ofthe reciprocal ofthe fraction ofthe population at risk and contained in the study grid 

(i>s) used to approximate the alongshore extent ofthe study grid population expanded on the 

basis of alongshore current movements and the offshore extrapolation of study grid abundance 

extended alongshore using both onshore and alongshore current movements with 90% CI.'s 

indicated. 

TENERA E9-055.0 5-192 Final 316(b) Demonstration 

March 1,2000 
5.2.4 Rockfishes 

p.11 

Blue rockfish complex (Sebastes spp. V/S. mystinus) - maximum duration 

O.SSO -

0.48 6 -

0.44 0 

o.sss -

0.33 0 — 

0.27 6 -

0.22 0 

0.166 -

0.110 -

O.OS8 -

o.ooo — 

R s along>hor e 

Analysis Period 3: Jul 1997-Jun 1998 

Density Extrapolated Ps off scale 

1/Ps = 42.1 

PM = 0.000456 ± 0.0700 

Estimate 

90% Cl. 

=>»» = 0.00468 

Ox Sx 10 x IS x 20 X 2SX SOx 3SX 40 x 

O k m B 7 k m -. 17 4 km.,- 26 1 k m 34 7 k m 43 4 k m S2 1 k m SOS k m 69 6 k m 

Siz e o f Populatio n Relativ e t o Stud y Orl d 

Equivalen t Distanc e Alongahor a 

Blue rockfish complex (Sebastes spp. V/S. mystinus) -maximum duration 

o.sso -

o.ooo — 

Analysis Period 4: Jul 1998-Jun 1999 

Density Extrapolated Ps off scale 

1/Ps = 60.0 

PM-0.00356 ±0.0576 

Estimate 

90% Cl. 

Ox 

O k m 

Sx 

8 7 km 

1 0 x 1 Sx 

1 7 4 k m 26 1 kr 

2 0X 2S x SOx 3Sx 40 x 

3 4 7 k m 43 4 k m 62 1 k m 60 8 k m 6S 6 k m 

Siz e o f Populatio n Relativ e t o Stud y Orl d 

Equivalen t Distanc e Alongahor a 

Figure 5.2.4-l3b. Total annual entrainment mortality (P^) and 90% confidence interval (CI.) 

as a function ofthe reciprocal ofthe fraction ofthe population at risk and contained in the study 

grid (j^) used to approximate the alongshore extent ofthe study grid population expanded on the 

basis of alongshore current movements and the offshore extrapolation of study grid abundance 

extended alongshore using both onshore and alongshore cunent movements with 90% CI.'s 

indicated. 

TENERA E9-055.0 5-193 Final 316(b) Demonstration 

March 1, 2000 
P.12 

5.2.4 Rockfishes 

a) 

140 

p 120 

S 

w

 100 

b) 

Morro Bay Area: Blue rockfish complex 

PSMFC PacFIN Groundfish Landings (all gear types) 

M 

U> 

e 

c 

3 

•o o 

J 40 

E 

o 

CJ 

80 -

60 

20 

OS. miniatus 

US. crameri 

US. mystinus 

-+-

^mm JJ 

1993 1994 1995 1996 

Year 

1997 199S 

Blue rockfish complex (Sebastes spp. V/S. mystinus) 

o 

CD 

CO 

c 

CO 

0) 

afra* 

CD 

E 

I 

o in 

c 

CO 

CD 

E 

Figure 5.2.4-14. Yearly abundance of blue-rockfish complex measured by two independent 

methods: a) Commercial fishery +landings of adults from Morro Bay area and, b) Mean 

number of adults and YOY observed per 50-meter subtidal benthic transect in the DCPP 

RWMP South Control area. Spline smoothing algorithm used to fit curve through points. 

TENERA E9-055.0 5-194 Final 316(b) Demonstration 

March 1,2000 
5.2.5 Painted Greenling 

5.2.5 Assessment of Painted Greenling (Oxylebius pictus) 

Oxylebius pictus Gill 1862; painted greenling; length to 26 cm; Prince William 

Sound, Alaska to Islas San Benito, central Baja California; intertidal to 94 m; 

grayish to brown, sometimes white spotted; throat usually spotted and three 

dark bands radiate from eye; dark spots on caudal, pectoral and pelvic fins 

(Miller and Lea 1972; Eschmeyer et al. 1983; Love 1996). 

The painted greenling (Oxylebius pictus) is a member ofthe family Hexagram m idae, which is 

found exclusively in the northern Pacific Ocean (Nelson 1994). Three ofthe four subfamilies 

occur along the California coast: Hexagramminae (one genus, Hexagrammos), Ophiodontinae 

(one species, Ophiodon elongatus), and Oxylebiinae (one species, O. pictus; Nelson 1994). 

Painted greenling are solitary bottom dwellers that inhabit the intertidal zone down to depths of 

94 m among or near cobble and boulder substrata, tending to mingle with the benthic flora in 

areas of surge (Miller and Lea 1972; Burge and Schultz 1973; Eschmeyer et al. 1983; Love 

1996). Crustaceans and polychaetes are important food items (Burge and Schultz 1973; Love 

1996). In turn, painted greenling are an important food item of Brandt's cormorant (Love 1996). 

Painted greenling was one ofthe most common fish in surveys of Diablo Cove and the vicinity in 

1970 and 1971 (Burge and Schultz 1973). In southern California they are most abundant at 

depths ranging from 15 to 31 m, but in central California the peak distribution moves inshore to a 

range of 5 to 22 m (Love 1996). Painted greenling are territorial and seem to have high site 

affinity (Love 1996). 

Painted greenling are oviparous and lay adhesive batches of demersal eggs on exposed rock 

surfaces with low lying algae, with males guarding the eggs (Fitch and Lavenberg 1975; Love 

1996). Reports ofthe spawning period and duration vary among sources with Moser (1996) 

reporting spawning activity from October-July and Fitch and Lavenberg (1975) indicating 

TENERA E9-055.0 5-195 Final 316(b) Demonstration 

March 1,2000 
5.2.5 Painted Greenling 

spawning takes place February-November. Females collected from Diablo Cove and the 

surrounding area in May and September contained developing and mature eggs (Burge and 

Schultz 1973). Females spawn three times during a 3 mo (summer) season in Puget Sound and at 

least three times over 7 mo (September-March) in Monterey Bay, California (DeMartini and 

Anderson 1980). The number of eggs produced annually ranges from ca. 12,000-28,500 

(DeMartini and Anderson 1980; Love 1996). Larvae are planktonic and can remain in the water 

column for 1-3 mo (DeMartini and Anderson 1980; Moser 1996). The larvae transform to 

juveniles at a size of approximately 15 mm (Kendall and Vinter 1984). 

Scientific literature gives no estimates of natural mortality rates for either early life stages or later 

(juvenile or adult) stages of painted greenling. Mortality rates have not been calculated for adults 

using age-frequency analyses because age distributions in the populations sampled were not 

stationary (DeMartini and Anderson 1980). Hatching success per brood ranged from 31 %± 9% to 

72% ± 6% (DeMartini 1987). Laboratory mortality rates during the yolk-sac stage for another 

family member, the greenling (Hexagrammos otakii), were calculated from survival curves as 

0.001-0.003 (Hamai and Kyushin 1964). Survival rates at the end ofthe yolk absorption period 

ranged from 13% to 38%. During the feeding period ofthe larvae, the mortality rate 

(0.018-0.083) depends on temperature, with higher temperatures conesponding to higher 

mortality rates (Hamai and Kyushin 1964). These laboratory-derived mortality rates were 

measured in the absence of natural mortality (e.g., predation) and, therefore, were not appropriate 

to use as the larval mortality rates of painted greenling. 

Longevity and age at maturation of painted greenling appear to vary with location. Their 

longevity was estimated at 8 yr from a 173 mm total length (TL) specimen collected in the 

vicinity of Diablo Canyon (Burge and Schultz 1973). In Monterey Bay, California the maximum 

longevity was estimated as 5 yr at 160 mm TL for males and 6 yr at 175 mm TL for females. Fish 

in Puget Sound had a maximum longevity of 6 yr at 200 mm TL for males and 8 yr at 215 mm 

TL for females (DeMartini and Anderson 1980). Age at 50% maturity was 3 yr for females and 2 

yr for males in Monterey Bay (DeMartini 1976; DeMartini and Anderson 1980). 

TENERA E9-055.0 5-196 Final 316(b) Demonstration 

March 1,2000 
P.15 

5.2.5 Painted Greenling 

Painted greenling have limited fishery value. They are typically taken incidentally by recreational 

and commercial fisheries while targeting other fishes (Fitch and Lavenberg 1975; Love 1996). 

Thus there are no stock assessments or catch records with which to compare losses attributable to 

power plant entrainment. 

5.2.5.1 Summary of Field Collections 

Painted greenling larvae were collected almost year round at the DCPP intake structure during 

the years 1996-1999 (Appendix H), with their highest abundance occurring in late March and 

May 1997 (Figure 5.2.5-1). It appears there were fewer painted greenling larvae during 1998 

than during either 1997 or 1999, especially during February and March 1998. This might have 

been due to the El Nino event that was detected along the central California coast in the fall of 

1997 (Lynn et al. 1998; NOAA 1999). There were 1,133 larval painted greenling in 553 bongo 

net subsamples collected at the DCPP intake structure between October 1996 and June 1999 

representing 12% ofthe subsamples collected and processed from that location during that 

period. 

Painted greenling larvae occurred in the DCPP study grid during most months except September 

1997, and August and September 1998 (Appendix H). The highest density occurred during May 

and June 1999 (Figure 5.2.5-2) and in the grid cells closest to shore. There were 372 larval 

painted greenling identified from 261 bongo net subsamples representing 9% ofthe study grid 

subsamples collected and processed from July 1997-June 1999. 

Standard lengths of all painted greenling larvae collected at the DCPP intake structure between 

October 1996 and June 1999 ranged from a minimum of 2.1 mm to a maximum of 7.9 mm 

(Figure 5.2.5-3). The central 98% of this length-frequency distribution resulted in minimum and 

maximum lengths for the analyses of 3.2 mm and 5.2 mm, respectively. The mean larval length 

in this distribution was 4.1 mm. The growth rate of larval painted greenling (0.083 mm/d) 

reported by Freeman et al. (1985) was used to estimate ages of entrained larvae. We assumed that 

the shortest larva ofthe central 98% ofthe length-frequency distribution was immediately posthatch and aged zero days. Consequently, the estimated ages of larvae entrained ranged from zero 

TENERA E9-055.0 - 5-197 Final 316(b) Demonstration 

March 1,2000 
P.16 

5.2.5 Painted Greenling 

days up to 24-70 d post-hatching for the largest larvae measured. On average, the estimated ages 

of painted greenling larvae entrained at DCPP ranged from 10-24 d post-hatching. Reported 

hatching size for painted greenling is less than 3.5 mm (Moser 1996). The fact that we observed 

some larvae smaller than the reported hatching lengths may be partly explained by natural 

variation of hatch lengths within the population and partly by the phenomenon of shrinkage 

following preservation (Theilacker 1980). 

Significant differences were detected between mean lengths (/-test: p < 0.041) and between 

length-frequency distributions (Kolmogorov-Smirnov test: p £ 0.002) of larval painted greenling 

from the DCPP intake structure and study grid despite the appearance of similarity between the 

two distributions (Figure 5.2.5-4). The mean standard lengths from the intake and study grid 

were 4.1 mm and 4.0 mm, respectively. The maximum difference between the length-frequency 

distributions detected by the Kolmogorov-Smirnov goodness offit test occurred at 4.1 mm, 

indicating that smaller individuals were collected from the DCPP intake. While these differences 

were statistically detectable and significant, we believe that the biological significance ofthese 

differences was low. 

5.2.5.2 Estimating Total Annual Entrainment 

The annual estimated mean entrainment for painted greenling larvae ranged from a minimum of 

8,410,000 (SE =800,000) in Analysis Period 2 to a maximum of 22,000,000 (SE =1,600,000) in 

Analysis Period 1 (Table 5.2.5-1). Values of 2-SE(ET) can be used to approximate 95% 

confidence intervals around the point estimates. These values for October 1996-September 1997 

and October 1997-September 1998 would not overlap, indicating that the differences between 

them is statistically significant. 

Estimates of Annual estimates of entrained painted greenling larvae adjusted to a long-term mean 

based on annual indices using weekly Intake Cove surface plankton tows (Figure 5.2.5-5) ranged 

from a minimum of 9,610,000 (SE =914,000) in Analysis Period 2 to a maximum of 24,200,000 

(SE =1,760,000) in Analysis Period 1 (Table 5.2.5-2). The average index for the years 1997 and 

1998 were 0.0023 and 0.0022 larvae/m^, respectively. The long-term average index was 0.0025 

TENERA E9-055.0 5-198 Final 316(b) Demonstration 

March 1,2000 
P.17 

5.2.5 Painted Greenling 

larvae/m3 for the years 1990-1998, yielding the ratio (7/7,) of 1.0990 for 1997 and 1.143 for 

1998 and indicating that larval greenling abundance was lower than the long-term average during 

1997 and 1998. The adjustment increased the differences between the estimates for Analysis 

Periods 1 and 2. 

NOTE: Entrainment estimates for painted greenling were not used to calculate FH or AEL 

models because no demographic data (e.g., larval survivorship) were available to parameterize 

these approaches. 

5.2.5.3 Empirical Transport Model (ETM) 

Monthly estimates of proportional entrainment (PE,) in each rth survey from the two years 

sampled ranged from a minimum of zero to a maximum of 0.0423±0.0393 (±\SE(PEi j) in 

February 1998 (Table 5.2.5-3). This maximum PE, was not associated with the maximum ft 

(0.252) which occurred in July 1997 and thus was proportionally less important during that 

analysis period. No larvae were collected at either the DCPP intake or from the study grid when 

both PE, and the proportion of larvae present in the rth survey period (Jj) were equal to zero. 

When PEj =0 but Jj>0, it indicated that larvae were collected at the DCPP intake during the 

survey period but not during the entrainment survey paired with the 72-hour study grid survey. 

During the Analysis Period 3, the highest PE, 's were all approximately 0.04, but only January 

1998 had a relatively large ft weighting factor (0.17) which meant it had proportionally greater 

influence on the annual entrainment mortality estimate. In Analysis Period 4, one ofthe lowest 

PE, values carried the greatest weighting factor j =0.23. 

Estimates of PM between analysis periods and for both larval durations are relatively similar and 

ranged from 0.032-0.067 (Figure 5.2.5-6). Since painted greenling larvae were dispersed 

throughout the study grid during most surveys (Figure 5.2.5-2), Ps was calculated using 

alongshore current movement and extrapolating study grid abundance offshore using onshore 

current movement. The estimates calculated using offshore extrapolation of study grid abundance 

were also similar between the two analysis periods and two larval durations and ranged from 

0.004-0.011. Estimates of PM for both analysis periods using either mean or maximum length in 

TENERA E9-055.0 5-199 Final 316(b) Demonstration 

March 1,2000 
P.18 

5.2.5 Painted Greenling 

calculating larval duration either declined are remained approximately the same when MPs 

increased. 

5.2.5.4 Interpretation of Assessment Results 

Painted greenling has very little commercial or recreational fishery value. Because ofthe absence 

of any commercial fishery for this species, there are no catch data or stock assessments with 

which to compare entrainment mortality rates (PM ). Results ofthe ETM modeling show that the 

power plant may annually entrain approximately 4-5% ofthe painted greenling larvae over an 

area 6 to 7 times the area ofthe study grid (Figure 5.2.5-6). 

Abundance of adult painted greenling was examined using data from the DCPP Receiving Water 

Monitoring Program studies on subtidal fishes (Figure 5.2.5-7). There was considerable variation 

in greenling abundance over the period of observation with one obvious decline in abundance 

from 1992 through 1994. This may have resulted from the extended El Nino events that occurred 

from 1991 through 1993 (Yoklavich et al. 1996) and again in 1994 (NOAA 1999). Annual mean 

density of painted greenling larvae from Intake Cove surface plankton tows show high larval 

production in 1992 and 1995, but no coherent trends (Figure 5.2.5-5). The absence of any 

evidence of long-term effects (>5 yr) on painted greenling abundance from these two sources 

indicates that entrainment of larvae by the power plant CWS is only removing excess larval 

production that does not affect local adult abundance or larval production. 

The lack of evidence of declining trends in adult abundance or larval production could also be the 

result of compensation for the additional larval mortality resulting from entrainment. If, as 

reported, painted greenling larvae transform into juveniles at a size of 15 mm and are planktonic 

for 1-3 mo (DeMartini and Anderson 1980; Moser 1996), then our results indicate that the larvae 

are only subject to entrainment for a very limited period oftime. The mean ofthe size frequency 

distribution for entrained larvae was 4.0 mm, and 99% of all the larvae ranged from 3.2 to 5.3 

mm (Figure 5.2.5-3). The period oftime represented by this size range is much less than the 

reported larval duration (up to 90 d) and may even be shorter if, as suspected, the lower sizes 

represent variation in hatch size. Only one larva was collected that was within the range of 

TENERA E9-055.0 - 5-200 Final 316(b) Demonstration 

March 1,2000 
FM9 

5.2.5 Painted Greenling 

Moser's (1996) reported length at flexion (7-9 mm). The absence of flexion and post-flexion 

length larvae in the samples may indicate that more developed larvae are able to avoid capture or 

that behavioral changes result in the larvae moving out ofthe plankton and into other habitats 

where they are not subject to capture or entrainment. These observations may also indicate that 

painted greenling larvae quickly settle out ofthe plankton and may have mechanisms in later 

stages that compensate for mortality of planktonic larvae since there do not appear to be declines 

in larval abundance through time. 

TENERA E9-055.0 5-201 Final 316(b) Demonstration 

March 1,2000 
P.20 

5.2.5 Painted Greenling 

Table 5.2.5-1. Estimated total annual entrainment (ET ) and standard error 

(SE(ET)) for painted greenling (Oxylebius pictus) larvae from the three 

analysis periods. 

Analysis Period ET SE(ET) 

1) Oct 23, 1996-Sep 30, 1997 22,000,000 1,600,000 

2) Octl, 1997-Sep30, 1998 8,410,000 800,000 

3) Jul 1, 1997-Jun 30, 1998 11,100,000 970,000 

Table 5.2.5-2. Estimated total annual adjusted entrainment (EAdj_T) and 

standard error ( SE(EAdJ_T ) ) for painted greenling (Oxylebiuspictus) larvae 

from the three analysis periods. 

Analysis Period EAdj_T SE(EMJ_T) 

1) Oct 23, 1996-Sep 30, 1997 

2) Octl, 1997-Sep 30, 1998 

3) Jul 1, 1997-Jun 30, 1998 

24,200,000 

9,610,000 

12,100,000 

1,760,000 

914,000 

1,110,000 

TENERA E9-055.0 5-202 Final 316(b) Demonstration 

March 1,2000 
P.21 

5.2.5 Painted Greenling 

Table 5.2.5-3. Painted greenling (Oxylebius pictus): Monthly estimates of proportional 

entrainment (PE, ) and annual proportion of larvae hatched in the rth survey period (Jt) and 

associated standard errors (SE) used in estimating entrainment mortality for two analysis 

periods. 

a) Analysis Period 3: July 1, 1997-June 30, 1998 

Survey Start Date PE, SE (V) ft 

b) Analysis Period 4: July 1, 1998-June 30, 1999 

Survey Start Date PE, SE(PE,) ft 

SE(f,) 

Jul 21, 1997 

Aug 25, 1997 

Sep 29, 1997 

Oct 20, 1997 

Nov 17, 1997 

Dec 10, 1997 

Jan 22, 1998 

Feb 26, 1998 

Mar 18, 1998 

Apr 15, 1998 

May 18, 1998 

Jun 8, 1998 

0.00894 

0.00954 

0 

0.0398 

0.00751 

0.0125 

0.0405 

0.0423 

0.0361 

0.00440 

0.00780 

0.0162 

0.00593 

0.0134 

0 

0.0474 

0.0106 

0.0144 

0.0206 

0.0393 

0.0255 

0.00341 

0.00318 

0.00515 

0.252 

0.0329 

0 

0.0310 

0.0191 

0.0333 

0.1703 

0.0296 

0.0345 

0.101 

0.089 

0.207 

0.016 

0.0046 

0 

0.0041 

0.0037 

0.0050 

0.0118 

0.0035 

0.0044 

0.0112 

0.0075 

0.0123 

SE ( / ) 

Jul 21, 

Aug 26, 

Sep 16, 

Oct 6, 

Nov 11, 

Dec 9, 

Jan 12, 

Feb 3, 

Mar 17, 

Apr 14, 

May 24, 

Jun 23, 

TENERA E9-055.0 

1998 

1998 

1998 

1998 

1998 

1998 

1999 

1999 

1999 

1999 

1999 

1999 

0.00285 

0 

0 

0 

0 

0.00741 

0.0153 

0.0181 

0.0116 

0.00924 

0.00997 

0.00747 

0.00305 

0 

0 

0 

0 

0.00827 

0.00478 

0.00464 

0.00362 

0.00450 

0.00338 

0.00208 

5-203 

0.0262 

0 

0 

0 

0 

0.0108 

0.124 

0.168 

0.236 

0.0775 

0.233 

0.125 

0.00366 

0 

0 

0 

0 

0.00196 

0.00499 

0.00562 

0.00960 

0.00524 

0.00962 

0.00601 

Final 316(b) Demonstration 

March 1,2000 
P.22 

5.2.5 Painted Greenling 

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o.oooPainted greenling (Oxylebius pictus) 

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M A 

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Survey Date 

T designatessurveywithOensity=0 

Figure 5.2.5-1. Weekly mean larval density (#/m3 + 1 S.E.) at the DCPP intake. 

TENERA E9-055.0 5-204 Final 316(b) Demonstration 

March 1,2000 
P.23 

5.2.5 Painted Greenling 

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TENERA E9-055.0 5-205 Final 316(b) Demonstration 

March 1,2000 
P.24 

5.2.5 Painted Greenling 

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TENERA E9-055.0 5-206 Final 316(b) Demonstration 

March 1,2000 
m 

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0.099 

0.088 

0.077 

0.066 

0.055 

0.044 

0.033 

0.022 

0.011 

0.000 

Depth Contours 

20 meters 

——» 40 meters 

^"" » 60 meters 

Point Buchon 

DCPP Intake 

Point San Luis 

Jul. 20,'98 Aug. 25,'98 Sep. 15,'98 Oct. 5, "98 Nov 10, "98 Dec. 8, '98 

Figure 5.2.5-2c (continued). Mean larval density (#/m1) collected in the DCPP study grid cells and at the entrainment sampling location. 

cn 

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0.044 

0.033 

0.022 

0.011 

0.000 

Depth Contours 

——— 20 meters 

• — • 40 meters 

^ — 60 meters 

Point Buchon 

DCPP Intake 

Point San Luis 

Jan. 11, '99 Feb. 2, "99 Mar. 16, '99 Apr. 13, "99 May 23, '99 Jun 22, '99 

Figure 5.2.5-2d (continued). Mean larval density (#/m3) collected in the DCPP study grid cells and at the entrainment sampling location. 

9 

CO 

ca 
P.27 

5.2.5 Painted Greenling 

Painted greenling (Oxylebius pictus) 

N=963 

1 5 — 

-

Occurrence 

0 

I I I I I I I 

"o Frequency 

IIIII I 

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2 . 0 2. 5 3. 0 3. 5 4. 0 4. 5 S.O 5. 5 

L( 

c 

jngth Category (mm) 

...,, . 1 1 • i * ' ' i ' • * i • • . i • • • , . • 

5 4 B 1 2 16 . 2 0 2 4 2 8 

Estimated age (days) 

Vlax 

4,*X 

• 

i i i 

i 

Figure 5.2.5-3. Length frequency of all measured larval fish collected in the entrainment 

samples. Minimum, median, mean, maximum, and central 98% ofthe larval lengths are noted. 

X-axis scale is not continuous at larger lengths. 

TENERA E9-055.0 5-209 Final 316(b) Demonstration 

March 1,2000 
P.28 

5.2.5 Painted Greenling 

15" 

10" 

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Painted greenling (Oxylebius pictus) 

Entrainment: N=107 

1% 

Min 

Mean 

IIIII I 

Median 

99% 

Max 

I'•r I I I » » I I | •ITMl" I' I I ' ' ' ' I 

2.3 2.8 . 3.3 3.8 4.3 4.8 5.3 5.8 6.3 

Grid: N=178 

Medianl Mean 

1% 

ill 

99% 

III, I,.,,I, 

Max 

' I ' ' • TJ^TT^J^"^7'TX X , ,1. , , | ,-P, , |-P>1"P 44IL | 

2.3 2.8 3.3 3.8 4.3 4.8 5.3 5.8 6.3 

Length Category (mm) 

Figure 5.2.5-4. Length frequency of measured fish from entrainment surveys that paired with 

grid surveys (both years combined). Minimum, median, mean, maximum, and central 98% ofthe 

larval lengths are noted. X-axis scale is not continuous at larger lengths. 

TENERA E9-055.0 5-210 Final 316(b) Demonstration 

March 1,2000 
P.29 

5.2.5 Painted Greenling 

LU 

CO 

1 

+• 

l»> 

E 

5|, Density Mean 

0.012 — 

o.on -E 

o.oio — 

0.009 ~ 

o.oos -E 

0.007-E 

o.ooe -E 

0.005 -E 

0.004 -E 

0.003 -E 

0.002 -E 

0.001 -E 

o.ooo — 

Painted greenling (Oxylebius pictus) 

-

1 

• 

IIIII I 

1990 1991 1992 1993 1994 1995 

Year 

1 

1996 

•1 

i 

1997 

l 

199E I 

Figure 5.2.5-5. Annual mean density +/- 2 standard errors (vertical lines) and grand mean 

density for all years combined (horizontal line) for the Intake Cove surface plankton tows. The 

annual mean densities are based on seven consecutive months ofdata (December through June) 

except for 1990, which had only five months (February through June). 

TENERA E9-055.0 5-211 Final 316(b) Demonstration 

March 1,2000 
P.30 

5.2.5 Painted Greenling 

Painted greenling (Oxylebius pictus) - mean duration 

Analysis Period 3: Jul 1997-Jun 1998 

Pa alongshore 

Estimate 

90% Cl. 

Danalty 

Extrapolated Ra 

PM = 0.00877 ±0.0521 

S l i » of Population Relativ e to Study Orld 

Equivalent Olstanoa Alongahor a 

Painted greenling (Oxylebius pictus) - mean duration 

Analysis Period 4: Jul 1998-Jun 1999 

Estimate 

90% Cl. 

8lz e of Population Relative to Study Orld 

Equivalent Olatanoa Alongahor a 

Figure 5.2.5-6a. Total annual entrainment mortality (p^) and 90% confidence interval (C.I.) as 

a function ofthe reciprocal ofthe fraction ofthe population at risk and contained in the study grid 

(/£ ) used to approximate the alongshore extent ofthe study grid population expanded on the 

basis of alongshore current movements and Uie offshore extrapolation of study grid abundance 

extended alongshore using both onshore and alongshore current movements with 90% CI.'s 

indicated. 

TENERA E9-055.0 5-212 Final 316(b) Demonstration 

March 1.2000 
5.2.5 Painted Greenling 

P.31 

Painted greenling (Oxylebius pictus) - maximum duration 

Pa alongshore 

Analysis Period 3: Jul 1997-Jun 1998 

Density Extrapolated Ps off scale 

1/Ps = 47.8 

Pu- 0.00910 ±0.0575 

Estimate 

90% Cl. 

Slx e of Population Relative to Study Orld 

Equivalent Distance Alongshor e 

Painted greenling (Oxylebius pictus) - maximum duration 

Analysis Period 4: Jul 1998-Jun 1999 

Density Extrapolated Ps off scale 

1/Ps = 63.9 

Pu = 0.00444 ±0.0310 

Estimate 

90% Cl. 

Siz e of Population Relative to Study Orld 

Equivalent Oiatanoa Alongahor a 

Ll_ 

Figure 5.2.5-6b. Total annual entrainment mortality (/£ ) and 90% confidence interval (CI.) as 

a function ofthe reciprocal ofthe fraction ofthe population at risk and contained in the study grid 

(p.) used to approximate the alongshore extent ofthe study grid population expanded on the 

basis of alongshore current movements and the offshore extrapolation of study grid abundance 

extended alongshore using both onshore and alongshore current movements with 90% CI.'s 

indicated. 

TENERA E9-055.0 5-213 Final 316(b) Demonstration 

March 1, 2000 
P.32 

O 

<D 

CO 

c 

CO 

"SJ 

E 

I 

o 

lit 

c 

CO 

cu 

E 

5.2.5 Painted Greenling 

i 1 1 1 1 1 1 n—i 1 1 1 1 1 1 1 r78 80 82 84 \ 86 88 90 92 94 

Plant Start-up 

Year 

i r 

96 98 

Figure 5.2.5-7. Mean number of painted greenlings observed per 50-meter subtidal benthic 

transect in the DCPP RWMP South Control area. Spline smoothing algorithm used to fit curve 

through points. 

TENERA E9-055.0 5-214 Final 316(b) Demonstration 

March 1,2000 
P.33 

5.2.6 Sculpins 

5.2.6 Assessment of Sculpins (Family Cottidae) 

Cottidae is a scorpaeniform family that comprises 70 genera worldwide (Nelson 1994). Forty-two 

species of sculpin occur along the California coast (Miller and Lea 1972), primarily in intertidal 

or shallow subtidal habitats. The ETWG selected three cottid species for assessment in the DCPP 

entrainment study: smoothhead sculpin (Artedius lateralis), snubnose sculpin (Orthonopias 

triads), and cabezon (Scorpaenichthys marmoratus). 

Intertidal and shallow subtidal fishes, including the cottids, display a wide range of life histories 

that defy broad demographic generalization. Species within the family Cottidae display a variety 

of life history patterns ranging from relatively short-lived to longer-lived species (Gibson 1969, 

1982; Miller 1979). The large staghorn sculpin (Leptocottus armatus), common in Pacific coast 

bays and estuaries, is known to live to 3 yr and reach sexual maturity after 1 yr (Jones 1962; 

Tasto 1975). The fluffy sculpin (Oligocottus snyderi) and the tidepool sculpin (O. maeulosus) 

have short lifespans and early maturation. This conclusion is based on growth rate data coupled 

with the scarcity of individuals older than 1.5 yr and on data showing early maturation and high 

reproductive output for fluffy sculpin (deVlaming et al. 1982). Cabezon, the largest ofthe North 

American cottids, may live 13 yr but only inhabits tidepools during its first or second year of life 

(O'Connell 1953). The demography of cottids is not well known. 

A detailed review ofthe demography of several species of cottids closely related to smoothhead 

sculpin (Artedius lateralis) will show why substitution of early life history characteristics from 

related taxa is not possible for target taxa from the Cottidae. Begle (1989) proposed a 

phylogenetic classification placing the genera Oligocottus and Clinocottus as the nearest relatives 

to the genus Artedius. As with smoothhead sculpin, sculpins in the genera Oligocottus and 

Clinocottus are oviparous; lay demersal, adhesive egg batches; show varying degrees of parental 

care ofthe eggs; and produce pelagic larvae. 

Though the demography of local species from these closely related genera (i.e., tidepool sculpin, 

fluffy sculpin, and woolly sculpin [Clinocottus analis]) is similar in many respects to that of 

smoothhead sculpin, information necessary to compute AEL and FH for this latter species is 

TENERA E9-055.0 5-215 Final 316(b) Demonstration 

March 1,2000 
P.34 

5.2.6 Sculpins 

lacking (Table 5.2.6-1). The tidepool sculpin achieves a maximum size of 8.9 cm, becomes 

sexually mature by 12 mo (Pierce and Pierson 1990), and primarily occurs in the intertidal zone. 

Using unvalidated ages, Pierce and Pierson (1990) reported mean annual fecundity ranges from 

103 eggs for an age class I female to 699 eggs for an age class III female. The fluffy sculpin also 

reaches a maximum size of ca. 8.9 cm (Eschmeyer et al. 1983) and a maximum age of 1.5 yr at 

Dillon Beach, California (Freeman et al. 1985). It may spawn more than once during its 

approximately 8 mo reproductive period (Grossman and deVlaming 1984) and is found in 

tidepools and shallow rocky areas from Sitka, Alaska to Rio Socorro, northern Baja California 

(Miller and Lea 1972). Instantaneous growth rates of wild-caught fluffy sculpin adults, estimated 

by length-frequency analyses, varied between males and females and range from 0.063 for an age 

1+ female to 1.059 for an age 0+ male (Freeman et al. 1985). 

The wooly sculpin (Clinocottus analis) is larger and longer lived than either the smoothhead 

sculpin or the two representatives ofthe genus Oligocottus. It attains a maximum size of 18 cm 

(Eschmeyer et al. 1983) and a maximum age of 8 yr for males and 6 yr for females (Wells 1986). 

This sculpin is found from the intertidal zone to 18 m depths and from Cape Mendocino, northern 

California to Punta Asuncion, central Baja California (Miller and Lea 1972). It spawns in 

tidepools at Point Fermin, southern California from September through November. Young-ofthe-year (YOY) recruit to tidepools in southern California from November to February (Wells 

1986). Egg incubation takes ca. 18-30 d in the laboratory (Eigenmann 1892; Budd 1940; Hubbs 

1966). Wells (1986) indicates that all specimens over 60 mm TL and between zero and 1 yr of 

age appear sexually mature with batch fecundity described by the linear function F=l 1.6TL620.6 (n=45; r=0.940; P<0.01). Males of this species appear to grow faster and to a larger size 

than females (Wells 1986). The largest female collected (110 mm) contained 784 eggs; the mean 

number of eggs was 242 per average reproductive female (74 mm; Wells 1986). Number of 

spawns per season is unknown, but multiple spawns are implied by tri-modal size distribution of 

ova present in gonads (Wells 1986). Based on Budd (1940) examining wooly sculpin and Morris 

(1951) examining bald sculpins, 11-25 mm fishes were surmised to be newly settled from the 

pelagic larval phase and hatched approximately 6-8 wk prior (Wells 1986). Despite these life 

TENERA E9-055.0 5-216 Final 316(b) Demonstration 

March 1,2000 
P.35 

•7 - i 

5.2.6 Sculpins 

history descriptions, there are no estimates of larval survivorship with which to parameterize the 

FH or AEL models for members ofthe Cottidae. 

5.2.6.1 Smoothhead sculpin (Artedius lateralis) 

Artedius lateralis (Girard 1854); smoothhead sculpin; length to 14 cm; Kodiak 

Island, Alaska to Cabo San Quintin, northem Baja California; intertidal to 13 

m; greenish to brown on top, cream to light brown below (Miller and Lea 

1972; Eschmeyer et al. 1983). 

The smoothhead sculpin is a common nearshore, intertidal cottid (Miller and Lea 1972). 

Spawning varies between locations: winter-spring in British Columbia (Marliave 1977) and June 

in Puget Sound (Matarese et al. 1989). Their eggs hatch into pelagic larvae in about 16 d at 

15.5°C (Budd 1940; Matarese et al. 1989). Larvae of this species have been collected in DCPP 

entrainment samples nearly year-round (Figure 5.2.6-1). Love (1996) indicates that these 

sculpins likely mature within their first year of life and probably live as long as 3 yr. 

The demographic data available for smoothhead sculpin and its close relatives (Table 5.2.6-1) do 

not provide sufficient information to compute AEL or FH. Estimates of fecundity and spawning 

periodicity are available for closely related species that likely compare favorably with A. lateralis 

based on their similar ecological roles, adult habitats, and close phylogenetic relationships. 

However, in the absence of any estimates of egg or larval survivorship, FH or AEL cannot be 

computed for this species. 

Recreational and commercial fisheries do not target most small intertidal and shallow subtidal 

cottids. This is one reason that the literature on these species is limited. The absence of any 

TENERA E9-055.0 5-217 Final 316(b) Demonstration 

March 1,2000 
P.36 

5.2.6 Sculpins 

population estimates from fishery management plans or other sources will make assessment of 

impacts on the smoothhead sculpin population difficult. 

Summary of Field Collections -

Estimates of smoothhead sculpin larval abundance showed distinct seasonal peaks at the DCPP 

intake structure during the years 1996-1999 (Appendix H), with greatest abundance occuring 

between April and July (Figure 5.2.6-1). There were 5,598 larval smoothhead sculpin identified 

from 1,320 bongo net subsamples collected at the DCPP intake structure between October 1996 

and June 1999 representing 28% of the samples collected and processed from the intake structure 

during that period. With the exception of one very high peak density in April 1998, the 

distribution of abundance and magnitude of density did not appear to be different between 1997 

and 1998. Although only entrainment surveys that were paired with study grid surveys were 

processed after September 1998, the abundance patterns appear to be similar to previous years. 

Larval smoothhead sculpin generally occurred with similar seasonality in the DCPP study grid 

and at the DCPP intake structure (Appendix H). The largest densities in the study grid occurred 

in July 1997, April 1999, and May 1999 (Figure 5.2.6-2). There were 676 smoothhead larvae 

identified from 312 bongo net subsamples representing 10% ofthe study grid samples collected 

and processed from July 1997-June 1999. Larval abundance appeared to track the 20 m isobath, 

with larvae likely concentrated inshore of this contour (Marliave 1986). Apparently, the higher 

density of this species in the southern portion ofthe study grid results from the fact that more of 

the area in the southern half of the grid is within the 0-20 m depth range. 

Standard lengths of 4,929 smoothhead sculpin larvae measured from samples collected at the 

DCPP intake structure between October 1996 and June 1999 ranged from 1.6 mm to 11.8 mm 

(Figure 5.2.6-3). The central 98% of this length-frequency distribution resulted in minimum and 

maximum lengths of 2.4 mm and 5.3 mm, respectively. The mean larval length in this distribution 

was 3.1 mm. Reported hatch size for this species ranged from 3.9-4.5 mm (Moser 1996). The 

fact that we observed some larvae smaller than the reported hatching lengths can be explained 

partly by natural variation of hatch lengths within the population and partly by the phenomenon 

TENERA E9-055.0 5-218 Final 316(b) Demonstration 

March 1,2000 
P.37 

5.2.6 Sculpins 

of shrinkage following preservation (Theilacker 1980). The growth rate applied to this species 

(0.08 mm/d) from Freeman et al. (1985) was used to estimate ages of entrained larvae. Assuming 

that the shortest larvae (either 1.6 or 2.4 mm) were immediately post-hatch and aged zero days, 

the estimated ages of larvae entrained could range from zero days up to 35-123 d post-hatching 

forthe largest larvae measured. The average estimated ages of smoothhead sculpin larvae 

entrained at DCPP ranged from 9-19 d post-hatching. 

Significant differences exist between mean lengths (/-test: p < 0.001) and between lengthfrequency distributions (Kolmogorov-Smirnov test: p < 0.001) of larval smoothhead sculpin from 

the DCPP intake structure and study grid, despite the appearance of similarity between the two 

distributions (Figure 5.2.6-4). The mean standard lengths from the intake and study grid were 3.1 

mm and 3.7 mm, respectively. The large sample size (655 larvae from the intake and 280 larvae 

from the study grid) causes the Mest to be highly sensitive to small differences between the 

means (Zar 1984). Median lengths were similar at 3.1 mm and 3.2 mm at the intake structure and 

in the grid, respectively. The maximum difference between the length-frequency distributions 

detected by the Kolmogorov-Smimov goodness offit test occurred at 3.9 mm, indicating that 

more large individuals were collected from the grid. While these differences were statistically 

detectable and significant, we believe that the biological significance ofthese differences is low. 

Estimating Total Annual Entrainment 

Annual mean entrainment estimates for smoothhead sculpin larvae ranged from 88,900,000 

(SE =3,660,000) in 1996-97 Analysis Period 1 to 96,100,000 (SE =9,410,000) in 1997-98 

Analysis Period 2 (Table 5.2.6-2). The estimates for 1997-98 Analysis Period 3 were slightly 

different than Analysis Period 2 because smoothhead sculpin larvae were collected during the 

summer and fall months of 1997 when the two periods did not overlap. Values of 2 • SE(Er) can 

be used to approximate 95% confidence intervals around the point estimates. Confidence 

intervals for the 1996-97 and 1997-98 estimates would overlap, indicating that the differences 

among them were probably not significant. 

TENERA E9-055.0 5-219 Final 316(b) Demonstration 

March 1,2000 
P.38 

5.2.6 Sculpins 

Annual entrainment estimates for smoothhead sculpin larvae adjusted to a long-term mean based 

on annual indices using weekly Intake Cove surface plankton tows (Figure 5.2.6-5) ranged from 

57,700,000 (SE =2,370,000) in Analysis Period 1 to 115,000,000 (SE=\ 1,300,000) in Analysis 

Period 2 (Table 5.2.6-3). The average index values for 1997 and 1998 were 0.0734 and 0.0397 

larvae/m^, respectively, while the long-term average index was 0.0476 larvae/m^ for the years 

1990-1998, yielding the ratio 111, of 0.649 for 1997, and 1.20 for 1998. Thus, the adjusted 

values increase the differences between the 1996-1997 and the 1997-1998 analysis periods. 

NOTE: Estimates of FH or AEL for smoothhead sculpin using annual entrainment were not 

calculated because no demographic data exists for this species. 

Empirical Transport Model (ETM) 

Monthly estimates of proportional entrainment (PE, ) in the surveys from the two analysis 

periods ranged from a minimum of zero to a maximum of 0.0729±0.0181 (±ISE(PE, J) in June 

1999 (Table 5.2.6-4). Both April and June 1999 demonstrated similar PE, values around 0.07, 

but the proportional entrainment estimate in April had greater weight with an annual proportion 

of larvae hatched in the ith survey period (Jj) equal to 0.30 as compared with an /=0.18 from 

June of 1999. When both PE, and Jj were equal to zero, there were no larvae collected at either 

the DCPP intake or the study grid. When PE, = 0 but Jj>0 (e.g., Sept.-Nov. 1997), larvae were 

collected at the DCPP intake during the survey period but not during the entrainment survey 

paired with the 72-hour study grid survey. The largest values of Jj occurred April through June 

in both analysis periods indicating that these were times of peak hatching for this species. 

Smoothhead sculpin adults are found in the shallow nearshore area (Miller and Lea, 1972). Study 

grid samples showed that the larvae were also distributed primarily in nearshore areas (Figure 

5.2.6-2). Therefore, Ps was calculated using only alongshore current movement to calculate point 

estimates of PM . Results for smoothhead sculpin show how large differences in estimated larval 

durations (9 vs. 35 d) can affect estimates of PM (Figures 5.2.6-6). Estimates of total 

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5.2.6 Sculpins 

entrainment mortality increased about 5% with increasing larval transport duration in both 

periods (Period 3, mean duration Pu =11% and max. duration PM =15%: Period 4, mean duration 

•PM =15% and max. duration PM =20%) with the second year being higher overall. Values for 

PM were greater in the second analysis period. The probability of entrainment is less for the 

shorter duration in both analysis periods because ofthe reduced time over which larval transport 

occurred. Estimates from longer larval durations showed that weaker alongshore currents 

resulting from the El Nino conditions during the 1997-98 analysis period resulted in a larger 

estimate of Ps and smaller areas of inference compared to the 1998-99 analysis period. 

Interpretation of Assessment Results 

Smoothhead sculpin has neither commercial nor recreational fishery value, and there is little 

information on its ecological role in the community. Because ofthe absence of any fishery for 

this species, no catch data can be used to compare harvest mortality rates to entrainment mortality 

rates (PM ). There are also no estimates of stock size or density that could be used to convert PM 

into an estimate of adult equivalent loss, assuming no compensatory mortality. 

Annual mean densities of smoothhead sculpin larvae from Intake Cove surface plankton tows did 

not show any long-term trends in abundance from 1990-1998 (Figure 5.2.6-5). Although the 

estimate for 1998 is close to the long-term mean density, the data overall show a large amount of 

variation among years. The data do not provide any evidence ofa reduction in larval production 

that would affect recruitment and eventually adult population density. Trends in adult populations 

of smoothhead sculpin were examined using data from the DCPP Receiving Water Monitoring 

Program studies on subtidal fishes. Mean abundance from three 50 m transects in an area 

approximately 1 km south of Diablo Cove and not contacted by the plant's thermal discharge 

combine data for smoothhead sculpin with data for other cottids because ofthe difficulties in 

identifying these small, cryptic fishes underwater (Figure 5.2.6-7). The data vary considerably 

among years, but the fitted curve shows a declining trend from 1992 through 1998. Although 

these data are variable the timing ofthe apparent decline is consistent with the life-span (~3 yr) 

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5.2.6 Sculpins 

and age of sexual maturity (-1-2 yr) for this species, since any reductions in adult density of 

smoothhead sculpin would only be expected to be detectable after several generations. 

The sizes ofthe majority ofthe entrained larvae ranged from 2.0 mm to 4.5 mm (Figure 5.2.6-3). 

Although larvae as large as 11.9 mm were entrained, there were few larvae greater than the 

reported size at flexion of 5.0-6.3 mm (Moser 1996). In fact, most ofthe larvae were less than 

the maximum hatch size of 4.5 mm reported by Moser (1996). This may indicate that smoothhead 

sculpin larvae are only subject to entrainment over a limited period of their larval development. It 

may also indicate that larger larvae are avoiding capture or that behavioral changes result in the 

larvae moving out ofthe plankton and into other habitats where they are not subject to 

entrainment or capture using our sampling methods. The considerable variation in adult densities, 

the absence ofa decreasing trend in larval abundance, and the relatively short developmental 

period over which larvae are entrained indicates that the removal of approximately 10-20% of 

the smoothhead sculpin larvae from an area 7-8 times that ofthe study grid does not negatively 

affect local adult populations or larval abundance. 

5.2.6.2 Snubnose sculpin (Orthonopias triads) 

Orthonopias triads (Starks and Mann 1911); snubnose sculpin; length to 10 cm. 

Farallon Islands, northern California to Isla San Geronimo, northern Baja 

California; intertidal to 30 m; green to reddish brown or orange above, with 

dark and light mottling; white below (Miller and Lea 1972; Eschmeyer et al. 

1983; Long 1992). 

Despite the common occurrence ofsnubnose sculpin in nearshore rocky subtidal and intertidal 

habitats, their life history remains relatively undescribed. Females are oviparous and spawn year 

round with peaks between February and October. The eggs are demersal and adhesive and hatch 

planktonic larvae (Feeney 1992; Moser 1996). Bolin (1941) conducted studies ofthe embryology 

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5.2.6 Sculpins 

and development of early larval stages of O. triads in laboratory rearing experiments. Egg 

incubation took 16-19 d at about 13°C, after which the larvae hatched at sizes ranging from 2.9-

3.8 mm. All larvae died within 10 d of hatching despite several regimes of aeration and nutrition, 

increasing by about 0.2 mm in length over that time (i.e., growth rate of 0.02 mm/d). Yolk sacs 

were exhausted by about 5 d. The growth described above, representing the first 5-6 d of life 

until the yolk stores were exhausted, probably underestimates the growth rate in the wild where 

they can feed successfully. The growth rate of 0.083 mm/d used to estimate larval age of 

entrained O. triads is from Freeman et al.'s (1985) description ofthe early life history of another 

intertidal cottid (O. snyderi). 

The demographic data available for O. triads do not provide sufficient information for 

computation of AEL or FH. Phylogenetic analyses indicate that the relationship of O. triads to 

sister cottids found in similar habitats remains unresolved (Begle 1989). Recreational and 

commercial fisheries do not target small intertidal and shallow subtidal cottids. This is one reason 

that the literature on these species is limited. In the absence of egg or larval survivorship 

estimates, the impact of entrainment on the smoothhead sculpin population will be assessed using 

only the ETM. 

Summary of Field Collections 

Estimates ofsnubnose sculpin larval abundance showed seasonal peaks in late spring and early 

summer at the DCPP intake structure during the years 1997 and 1998 (Figure 5.2.6-8). There 

were 4,533 snubnose sculpin larvae identified from 1,422 bongo net subsamples collected at the 

DCPP intake structure between October 1996 and June 1999 representing 31 % ofthe samples 

collected and processed from the intake structure during that period. There appeared to be 

relatively compressed period of larval abundance in April though July of 1998 compared to a 

more protracted spawning season in 1997 that lasted from February through September. This may 

have been related to the El Nino event that occurred during late 1997 (Lynn et al. 1998; NOAA 

1999) as substantial increases in water temperatures and lowered productivity negatively affected 

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larval production and survival. Monthly samples collected in 1999 show larval densities similar 

in timing with 1997. 

Larval snubnose sculpin generally occurred in the DCPP study grid with similar seasonality to 

that observed at the DCPP intake structure (Appendix H). The 447 snubnose larvae identified 

from 201 bongo net subsamples represented 7% ofthe fishes collected and processed from July 

1997-June 1999 study grid samples. Thus, snubnose larvae were less common in the study grid 

than at the intake structure where their larvae were found in 31% ofthe samples. The peak 

abundances in the study grid occurred in July 1997 (Figure 5.2.6-9). During July 1997 and other 

surveys, snubnose sculpin larvae were typically more abundant in the nearshore areas ofthe grid. 

Similar to smoothhead sculpin, spatial distribution of larval snubnose abundance appeared to 

follow the 20 m isobath. Marliave (1986) found that larvae ofrocky intertidal and nearshore 

fishes may resist offshore transport, and possibly even alongshore transport, to remain 

concentrated against the shore. Larvae of this species occurred more often in the southern portion 

ofthe study grid because more ofthe area in the southern half of the grid is within the 0-20 m 

depth range. 

Standard lengths of all measured snubnose sculpin larvae collected at the DCPP intake structure 

between October 1996 and June 1999 (3,750 larvae) ranged from 1.7 mm to 8.5 mm (Figure 

5.2.6-10). The central 98% of this length-frequency distribution resulted in minimum and 

maximum lengths used for analyses of 2.6 mm and 6.1 mm, respectively. The mean larval length 

in this distribution was 3.6 mm. Reported hatching size for this species ranged from 2.6-3.8 mm 

(Moser 1996). The fact that we observed some larvae smaller than the reported hatching lengths 

can be explained partly by natural variation of hatch lengths within the population and partly by 

the phenomenon of shrinkage following preservation (Theilacker 1980). The growth rate applied 

to this species (0.08 mm/d) from Freeman et al. (1985) was used to estimate ages of entrained 

larvae. Assuming that the shortest larvae (either 1.7 or 2.6 mm) were immediately post-hatch and 

aged zero days, then the estimated ages of larvae entrained could range from zero days up to 42-

82 d post-hatching for the largest larvae measured. The average estimated ages ofsnubnose 

larvae entrained at DCPP ranged from 11-22 d post-hatching. 

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5.2.6 Sculpins 

Distributions ofsnubnose sculpin larval lengths at the DCPP intake structure and in the study grid 

were compared using a Kolmogorov-Smirnov test (Figure 5.2.6-11). The test did not detect a 

significant difference between the two distributions (p > 0.14). Larvae in the study grid showed a 

bimodal size distribution, with a greater proportion of larger individuals represented in the grid 

relative to collections at the intake structure. A /-test detected a significant difference (p < 

0.0134) between mean lengths for the two locations: 3.5 mm at the DCPP intake and 3.7 mm in 

the study grid. The large sample size (380 larvae from the intake and 161 larvae from the study 

grid) causes the /-test to be highly sensitive to small differences between the means (Zar 1984). 

While the difference between the means was statistically significant, we believe that the 

biological significance ofthe difference is low. 

Estimating Total Annual Entrainment 

The annual estimated mean entrainment ofsnubnose sculpin larvae ranged from a minimum of 

59,800,000 (SE =4,120,000) in 1997-98 Analysis Period 2 to a maximum of 85,600,000 

(SE =3,490,000) in 1996-97 Analysis Period 1 (Table 5.2.6-5). The estimates for 1997-98 

Analysis Period 3 were slightly different than Analysis Period 2 because snubnose sculpin larvae 

were collected during the summer and fall months of 1997 when the two periods did not overlap. 

Values of 2-SE(ET) can be used to approximate 95% confidence intervals around the point 

estimates. These confidence intervals for October 1996-September 1997 and October 1997-

September 1998 would not overlap, indicating that the differences between them were probably 

statistically significant. 

The adjusted estimates of annual entrainment ofsnubnose sculpin larvae ranged from 83,500,000 

(SE =5,750,000) in 1997-98 Analysis Period 2 to 110,000,000 (S£ =4,480,000) in 1996-97 

Analysis Period 1 (Table 5.2.6-6) based on annual indices using weekly Intake Cove surface 

plankton tows (Figure 5.2.6-12). The average index values forthe years 1997 and 1998 are 0.028 

and 0.025 larvae/m^, respectively, while the long-term average index is 0.036 larvae/m3 for the 

years 1990-1998, yielding the ratio 111, of 1.28 for 1997 and 1.40 for 1998. The adjustments 

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5.2.6 Sculpins 

increased the estimates for all three periods but did not decrease the relative differences among 

them. 

NOTE: Estimates of FH or AEL for snubnose sculpin using annual entrainment were not 

calculated because no demographic data exists for this species. 

Empirical Transport Model (ETM) 

Monthly estimates of proportional entrainment (PE,) in the surveys from the two analysis 

periods ranged from a minimum of zero to a maximum of 0.859±0.911 (±\SE( PE, I) in 

December 1997 (Table 5.2.6-7). However, this maximum value was accompanied by a relatively 

low estimate ofthe annual proportion of larvae hatched in the rth survey period (Jj) indicating 

that relatively few snubnose sculpin larvae were collected at the intake during this month. When 

both PE, and J were equal to zero, no larvae were collected at either the DCPP intake or from 

the study grid. When PE, = 0 but J>0, larvae were collected at the DCPP intake during the 

monthly survey period but not during the entrainment survey paired with the 72-hour study grid 

survey. The largest values of J, occurred during April through July in both analysis periods. 

During the 1996-1997 analysis period, the largest values of PE, occurred during periods when 

the Jj were lowest, indicating that the high PE, values resulted from low entrainment densities 

used to estimate abundance in nearshore areas ofthe study grid. During the 1997-1998 analysis 

period these surveys were also associated with the largest values of PE, . 

Results of ETM for snubnose sculpin showed how differences in estimated larval durations (11 

vs. 42 d) can affect estimation of PM (Figures 5.2.6-13). Study grid samples showed that 

snubnose sculpin larvae were primarily distributed in nearshore areas (Figure 5.2.6-9) despite the 

fact that adults have been found from the intertidal zone out to depths of 30 m (Miller and Lea 

1972). Based on observed larval and reported adult distributions, Ps was calculated using both 

alongshore current movement and extrapolating study grid abundance offshore using onshore 

current movement before extending alongshore. The probability of entrainment was typically less 

for the shorter duration within an extrapolation class because ofthe reduced time period over 

which larval transport occurred. Estimates of PM using alongshore transport were larger for the 

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1998-1999 analysis period (0.24: Figure 5.2.6-13b) than for the 1997-1998 analysis period 

(0.14) and were greater than within-period differences between estimates based on different 

larval durations. Estimates of PM using offshore abundance extrapolation and maximum 

transport duration were very similar between periods (i.e., 0.021 for 1998-1999 and 0.023 for 

1997-1998). The increased onshore transport caused by the El Nino conditions during the 1997-

1998 period reduced the differences iii the estimates by compensating for the large differences in 

alongshore transport between the two periods. 

Interpretation of Assessment Results 

Snubnose sculpin has neither commercial nor recreational fishery value and there is little 

information on its ecological role in the community. Because ofthe absence of any fishery for 

this species, no catch data can be used to compare harvest mortality rates to entrainment mortality 

rates (PM ). There also are no stocks or adult density estimates that could be used to convert PM 

into equivalent adult losses (assuming no compensatory mortality). 

Annual mean density ofsnubnose sculpin larvae from Intake Cove surface plankton tows shows 

a declining trend in abundance over time, although the estimates for 1997 and 1998 appear to 

have leveled off (Figure 5.2.6-12). Reduced larval production may affect recruitment and 

eventually adult population densities. Reductions in adult density due to entrainment ofsnubnose 

sculpin larvae could be expected to appear only after several generations. There were no 

estimates in the scientific literature ofthe life-span or age at sexual maturity for snubnose 

sculpin, though they are likely to be similar to other small, nearshore cottids: 1-3 yr for sexual 

maturity and 2-7 yr for longevity (Gibson 1969; Miller 1979; deVlaming et al. 1982; Grossman 

and deVlaming 1984; Freeman et al. 1985; Wells 1986; Pierce and Pierson 1990). 

Adult abundance ofsnubnose sculpin observed in the DCPP Receiving Water Monitoring 

Program (RWMP) studies on subtidal fishes varies considerably through time, but shows a 

downward trend from the early 1990s through 1998 (Figure 5.2.6-14). These data were collected 

along three 50 m transects in an area approximately 1 km south of Diablo Cove not contacted by 

the plant's thermal discharge. Since the potential life-span and age at sexual maturity ofsnubnose 

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5.2.6 Sculpins 

sculpin are less than the time since power plant operation began, there has been sufficient time 

for losses in the adult population to occur as a result ofa decrease in larvae. Thus, it appears that 

larval entrainment mortality ofsnubnose sculpin may be a factor in the reduction of adult 

abundance in the vicinity of DCPP. 

Snubnose sculpin have a smaller geographical distribution (Farallon Islands, northern California 

to Isla San Geronimo, northern Baja California) than other central California sculpins 

(Eschmeyer et al. 1983; Love et al. 1996). Although the results ofthe ETM evaluated using 

extrapolated abundance implying a large population area, the more restricted distribution of this 

taxon indicates that an estimate of PM closer to the values estimated using alongshore transport 

alone may be more appropriate. These estimates range from approximately 10% to over 20%, 

depending upon larval duration and sampling period (Figures 5.2.6-13). Based on Moser's 

(1996) reported size at flexion of 4.2-4.7 mm, the length range of larvae entrained shows that 

post-flexion larvae are still subject to entrainment (Figure 5.2.6-10). This also indicates that 

snubnose sculpin larvae have a prolonged exposure to entrainment. The prolonged exposure 

period and the levels of entrainment mortality estimated by PM may partially explain other 

results that show long-term declines in larval abundance in intake samples (Figure 5.2.6-12) and 

declines in local adult abundance (Figure 5.2.6-14). 

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5.2.6.3 Cabezon (Scorpaenichthys marmoratus) 

Scorpaenichthys marmoratus (Ayres 1854); cabezon; length to 99 cm; Sitka, 

Alaska to Punta Abreojos, central Baja California; intertidal to approx. 85 m; 

brown, reddish, or greenish above whitish or greenish below (Miller and Lea 

1972; Eschmeyer etal. 1983). 

The cabezon (Scorpaenichthys marmoratus) is the largest North American species of marine 

cottid and occurs over the nearshore continental shelf from depths of 85 m up to the intertidal 

zone (O'Connell 1953; Matarese et al. 1989). Cabezon are a popular sport fish and are also 

landed commercially (Fitch and Lavenberg 1971; Lamb and Edgell 1986). Females are oviparous 

and lay demersal, adhesive eggs in rocky crevices or on algae; males guard the egg nest until the 

pelagic larvae hatch (Burge and Schultz 1973; Feder et al. 1974; Matarese et al. 1989). Moser 

(1996) indicates that cabezon larvae hatch at 3-6 mm. 

Larvae appear in the water column around November or December and recruit to tidepools at 

around 40 mm SL in March off Moss Beach, California (RR. Harry unpubl. data cited in 

O'Connell 1953), implying a 3-4 mo planktonic duration. Females begin to mature in their third 

year between 25-48 cm SL (Fitch and Lavenberg 1971), and all are mature by year five (Starr et 

al. 1998). Fecundity for this species has been reported in several sources: 45,000 eggs for a 43 

cm SL specimen and 95,000 eggs for a 65 cm SL specimen (Hart 1973); mean fecundity of 

48,700 eggs for a 1.4 kg female and 97,600 eggs for a 4.6 kg female (O'Connell 1953; Bane and 

Bane 1971); and up to 152,000 eggs from a 76 cm SL female (Starr et al. 1998). O'Connell 

(1953) states that females spawn more than a single batch of eggs per year. Females live to 13 yr 

and males to 9 yr (O'Connell 1953). 

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5.2.6 Sculpins 

As with other members ofthe Cottidae, there are insufficient data to parameterize the FH and 

AEL approaches for impact assessment. No independent estimates of survivorship for early life 

stages prior to entrainment or later life stages are available from the literature. Thus, the impact 

of entrainment on this species' population will be assessed using only the ETM. 

Summary of Field Collections 

Estimates of cabezon larval abundance showed distinct seasonal peaks at the DCPP intake 

structure during the years 1996-1999 (Appendix H) with an apparent trend of decreasing 

abundance at the intake over the same period (Figure 5.2.6-15). There were 1,938 larval cabezon 

identified from 575 bongo net subsamples collected at the DCPP intake structure between 

October 1996 and June 1999 representing 12% ofthe entrainment samples collected and 

processed during that period. The spawning period for cabezon in winter 1996-1997 was longer 

and had higher abundances than the winter 1997-1998 spawning period. This difference may 

have been related to the El Niiio event that occurred during late 1997 (Lynn et al. 1998; NOAA 

1999) as substantial increases in water temperatures and lowered productivity negatively affected 

larval production and survival. The limited samples available from the winter 1998-1999 

spawning period appear to show similar timing as previous years. 

The seasonality of larval cabezon in the DCPP study grid was similar to the timing observed from 

the samples at the DCPP intake structure (Figure 5.2.6-16). There were 887 cabezon larvae 

identified from 326 bongo net subsamples (Appendix H) representing 11% of the study grid 

samples collected and processed from July 1997-June 1999. The spatial distribution of larval 

cabezon abundance in the study grid during 1997-1998 Analysis Period 3 appeared primarily 

constrained against the shoreward side ofthe study grid. During 1998-1999 Analysis Period 4, 

cabezon larvae appeared to be more widely distributed in the study grid. The stronger alongshore 

currents during the second analysis period may account for this difference. Larval dispersal may 

have been more limited during the El Nino conditions present during the 1997-1998 analysis 

period due to weaker alongshore and stronger onshore currents. 

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Standard lengths of all cabezon larvae collected at the DCPP intake structure between October 

1996 and June 1999 and measured (1,537 larvae) ranged from a minimum of 2.3 mm to a 

maximum of 8.4 mm (Figure 5.2.6-17). The central 98% of this length-frequency distribution 

resulted in minimum and maximum lengths of 3.7 mm and 6.1 mm, respectively, that were used 

for calculating larval duration. The mean length of this distribution was 4.8 mm. Reported 

hatching size for this species ranged from 3-6 mm (Moser 1996). The fact that we observed some 

larvae smaller than the reported hatching lengths can be explained partly by natural variation of 

hatch lengths within the population and partly by the phenomenon of shrinkage following 

preservation (Theilacker 1980). The growth rate applied to this species (0.3 mm/d) was derived 

from O'Connell (1953) and Moser (1996) and was used to estimate ages of entrained larvae. 

Assuming that the shortest larvae (either 2.3 or 3.7 mm) were immediately post-hatch and aged 

zero days, the estimated ages of larvae entrained could range from zero days up to 8-20 d posthatching forthe largest larvae measured. The average estimated ages of cabezon larvae entrained 

at DCPP ranged from 4-8 d post-hatching. 

Distributions of cabezon larval lengths at the DCPP intake structure and in the study grid were 

compared using a Kolmogorov-Smirnov test (Figure 5.2.6-18). The test detected a significant 

difference between the two distributions (p < 0.001). Larvae in the study grid had a greater 

proportion of smaller individuals relative to collections at the intake structure. A /-test also 

detected a significant difference (p < 0.002) between the mean lengths for the two locations: 

4.7 mm at the DCPP intake and 4.8 mm in the study grid. While these differences were 

statistically significant, we believe that the biological significance ofthese differences was low. 

Estimating Total Annual Entrainment 

The annual estimated mean entrainment of cabezon larvae ranged from 14,700,000 

(SE = 1,460,000) in 1997-98 Analysis Periods 2 and 3 to 35,700,000 (SE =2,720,000) in 1996-

97 Analysis Period 1 (Table 5.2.6-8). Values of 2 • SE(EJ.) can be used to approximate 95% 

confidence intervals around the point estimates. The confidence intervals for the 1996-97 and 

1997-98 periods would not overlap, indicating that the differences between them were probably 

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5.2.6 Sculpins 

statistically significant. The estimates for Analysis Period 3 are the same as Analysis Period 2 

because all ofthe cabezon were collected during the October-June period when the two periods 

overlapped (Figure 5.2.6-15). 

Annual estimates of entrained cabezon larvae, adjusted to a long-term mean based on annual 

indices using weekly Intake Cove surface plankton tows (Figure 5.2.6-19) ranged from 

36,300,000 (SE =3,600,000) in Analysis Periods 2 and 3 to 51,900,000 (SE =3,950,000) in 

Analysis Period 1 (Table 5.2.6-9). The average index for the years 1997 and 1998 are 0.0076 and 

0.0045 larvae/m^, respectively, while the long-term average index is 0.011 larvae/m^ forthe 

years 1990-1998, yielding the ratio 7/1, of 1.45 for 1997 and 2.47 for 1998. The adjustments 

increases the estimates of abundance and decreases the differences among them. 

NOTE: Estimates of FH or AEL for cabezon using annual entrainment were not calculated 

because there were no demographic data available for this species. 

Empirical Transport Model (ETM) 

Monthly estimates of proportional entrainment (PE,) in the surveys from the two analysis 

periods ranged from a minimum of zero to a maximum of 0.106±0.103 {±\SE(PE, j) in October 

1997 (Table 5.2.6-10). However, this maximum PE, value was not accompanied by a maximal 

estimate ofthe annual proportion of larvae hatched in the rth survey period (J,) so it was 

proportionally less important to the estimate of annual entrainment mortality than other values 

with higher J's. Periods when both PE, and Jj were equal to zero indicated that no larvae were 

collected at either the DCPP intake or from the study grid. When PE, = 0 but Jj>0, larvae were 

collected at the DCPP intake during the survey period but not during the entrainment survey 

paired with the 72-hour study grid survey. The largest values of J occurred from DecemberFebruary in both analysis periods indicating that these were times of high larval abundance at the 

intake structure. 

Estimates of PM for either alongshore current transport or offshore abundance extrapolation 

during both analysis periods were relatively similar and ranged from 0.006 to 0.03 (Figures 

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rr" 1"

5

 f 

5.2.6 Sculpins 

i 

i 

5.2.6-20). Cabezon adults have been found to depths of 75 m (Miller and Lea 1972) and their 

larvae were distributed throughout the study grid (Figure 5.2.6-16). Therefore, Ps was calculated 

using both alongshore current movement and extrapolating study grid abundance offshore using 

onshore current movement before extending it alongshore. Larval durations calculated using the 

mean and maximum larval lengths (central 98% of length distribution) only differed by 4 d (4 vs. 

8 d). This similarity in duration resulted in relatively small values of PM and rapid decline in 

their value with increasing Ps. Thus, it appears that cabezon larvae were entrainable over a 

relatively short period of their development. 

Interpretation of Assessment Results 

Cabezon has both commercial and recreational fishery value. Combined reported landings at the 

ports of San Luis and Morro Bay have varied during 1975-1998 from zero in 1975 to a high of 

78 MT in 1997 with an average of 9.7 MT (Figure 5.2.6-21). From 1995-1998, the combined 

average catch increased dramatically to over 60 MT/yr as a result of increased fishing effort 

stimulated by a high demand for cabezon in the 'live-fish' fishery. Juvenile and adult cabezon 

abundance examined using data from the DCPP Receiving Water Monitoring Program (RWMP) 

studies on subtidal fishes appears to be a declining since 1993 (Figure 5.2.6-21). Mean 

abundance ofjuvenile and adult cabezon was estimated from three 50 m transects in an area 

approximately 1 km south of Diablo Cove and not contacted by the plant's thermal discharge. 

This decline likely reflects the increased 'live-fish' fishery activity targeting young, nearshore 

species. Increases in the activity of fisherman in the 'live-fish' fishery near DCPP has been noted 

since approximately 1995. There does not appear to be a similar long-term abundance decline for 

cabezon larvae from the Intake Cove surface plankton tows; mainly due to high abundance in 

1995 (Figure 5.2.6-19). In addition, the narrow size range of larvae entrained by the power plant 

(central 98% of length-frequency distribution ranged from 3.7-6.1 mm) indicates that cabezon 

larvae are exposed to entrainment for a relatively short period oftime (Figure 5.2.6-17). 

Additionally, most larvae entrained were shorter than the reported length at flexion of 7.0 mm 

(Moser 1996). While it remains unclear whether local cabezon populations are in decline after 

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5.2.6 Sculpins 

examining these data, the size range of entrained larvae and relatively low estimates of PM can 

lead to the conclusion that larval entrainment mortality is not affecting local adult populations. 

Empirical transport modeling results indicate that the power plant may annually entrain 

approximately 1.5-3.5% ofthe cabezon larvae in an area 2-3 times the size ofthe study grid 

(assuming alongshore transport only) but less than 1% of larvae in an area from 4-22 times the 

size ofthe study grid (assuming both alongshore and offshore transport). Using this range of 

values, an estimate of PM = 0.015 or 1.5% was used to estimate entrainment effects on cabezon 

landings assuming no compensatory mortality. Based on landings and revenues of cabezon in the 

Morro Bay area from 1998 (75.2 MT and $592,300; PSMFC PacFIN database), the average 

dollar loss to the cabezon fishery (assuming a '1.5% proportional loss) due to larval entrainment at 

DCPP would be approximately $9,000/yr. 

TENERA E9-055.0 5-234 Final 316(b) Demonstration 

March 1,2000 

i 

I 
P.53 

rr"'" 

5.2.6 Sculpins 

Table 5.2.6-1. Summary of known demography for four closely related cottid species; 

x indicates data available from published sources; * indicates length-frequency data to 

estimate total adult mortality is available from this study; — indicates no data available. 

S S S ^ e @ ^ e * ^ta^

e 

Species '**

 b"va" 0duU Fecundity maturity Spawning Longevity Growth Duration 

A. lateralis — 

O. maeulosus — 

O. snyderi — 

C. analis — 

X 

X 

X 

X 

X 

X 

X 

X 

1

 Egg stage duration 

2 Planktonic larval duration 

Table 5.2.6-2. Estimated total annual entrainment (ET ) and standard error 

(SE(ET )) for smoothhead sculpin (Artedius lateralis) larvae from the three 

analysis periods. 

Analysis Period ET 

1) Oct 23, 1996-Sep 30, 1997 88,900,000 

2) Oct 1, 1997-Sep 30, 1998 96,100,000 

3) Jul 1, 1997-Jun 30, 1998 107,000,000 

SE(ET) 

3,660,000 

9,410,000 

9,490,000 

Xi 

XL2 

TENERA E9-055.0 5-235 Final 316(b) Demonstration 

March 1,2000 
P.54 

5.2.6 Sculpins 

Table 5.2.6-3. Estimated total annual adjusted entrainment (EAd/_T) and 

standard error (SE(EAdJ_T)) for smoothhead sculpin (Artedius lateralis) 

larvae from the three analysis periods. 

Analysis Period EAdj_T SE(EAdj_T) 

1) Oct 23, 1996-Sep 30, 1997 57,700,000 2,370,000 

2) Oct 1, 1997-Sep 30, 1998 115,000,000 11,300,000 

3) Jul 1, 1997-Jun 30, 1998 129,000,000 11,400,000 

TENERA E9-055.0 5-236 Final 316(b) Demonstration 

March 1,2000 
P.55 

5.2.6 Sculpins 

Table 5.2.6-4. Smoothhead sculpin (Artedius lateralis): Monthly estimates of proportional 

entrainment (PE,) and annual proportion of larvae hatched in the rth survey period (Jj) and 

associated standard errors (SE) used in estimating entrainment mortality for two analysis periods. 

a) Analysis Period 3: July 1, 1997-June 30, 1998 

Survey Start Date 

Jul 21, 1997 

Aug 25, 1997 

Sep 29, 1997 

Oct 20, 1997 

Nov 17, 1997 

Dec 10, 1997 

Jan 22, 1998 

Feb 26, 1998 

Mar 18, 1998 

Apr 15, 1998 

May 18, 1998 

Jun 8, 1998 

PE, 

0.00600 

0.0236 

0 

0 

0 

0 

0 

0 

0.0166 

0.0431 

0.0354 

0.0380 

SE(PE,) 

0.00248 

0.00797 

0 

0 

0 

' 0 

0 

0 

0.00453 

0.0115 

0.00750 

0.00685 

f 

0.112 

0.0175 

0.00235 

0.00016 

0.00022 

0 

0.00251 

0.00173 

0.0317 

0.453 

0.161 

0.219 

SE(j) 

0.00534 

0.00111 

0.000440 

0.0000900 

0.000110 

0 

0.000440 

0.000240 

0.00165 

0.0163 

0.00646 

0.00861 

b) Analysis Period 4: July 1, 1998-June 30, 1999 

Survey Start Date 

Jul 21, 

Aug 26, 

Sep 16, 

Oct 6, 

Nov 11, 

Dec 9, 

Jan 12, 

Feb 3, 

Mar 17, 

Apr 14, 

May 24, 

Jun 23, 

1998 

1998 

1998 

1998 

1998 

1998 

1999 

1999 

1999 

1999 

1999 

1999 

PE, 

0.00466 

0.00583 

0 

0 

0 

0 

0.0194 

0.0284 

0.0165 

0.0716 

0.0440 

0.0729 

SE(PE,} 

0.00229 

0.00619 

0 

0 

0 

0 

0.0104 

0.010 

0.00483 

0.0222 

0.00973 

0.0181 

f 

0.0301 

0.00198 

0 

0 

0 

0 

0.0157 

0.0511 

0.0915 

0.300 

0.329 

0.180 

SE(f,) 

0.00155 

0.000360 

0 

0 

0 

0 

0.00133 

0.00214 

0.00351 

0.00759 

0.00788 

0.00471 

TENERA E9-055.0 5-237 Final 316(b) Demonstration 

March 1,2000 
P.56 

5.2.6 Sculpins 

Table 5.2.6-5. Estimated total annual entrainment (ET ) and standard error 

(SE(ET)) for snubnose sculpin (Orthonopias triads) larvae from the three 

analysis periods. 

Analysis Period E^. SE(E^.) 

1) Oct 23, 1996-Sep 30, 1997 85,600,000 3,490,000 

2) Oct 1, 1997-Sep 30, 1998 59,800,000 4,120,000 

3) Jul 1, 1997-Jun 30, 1998 75,500,000 4,094,000 

Table 5.2.6-6. Estimated total annual adjusted entrainment (EAdj_T) and 

standard error (SE(EMJ_T)) for snubnose sculpin (Orthonopias triads) larvae 

from the three analysis periods. 

Analysis Period EAdj_T SE(EMJ.T) 

1) Oct 23, 1996-Sep 30, 1997 110,000,000 4,480,000 

2) Octl, 1997-Sep30, 1998 83,500,000 5,750,000 

3) Jul 1, 1997-Jun 30, 1998 105,000,000 5,720,000 

TENERA E9-055.0 5-238 Final 316(b) Demonstration 

March 1,2000 
P.57 

5.2.6 Sculpins 

Table 5.2.6-7. Snubnose sculpin (Orthonopias triads): Monthly estimates of proportional 

entrainment (PE,) and annual proportion of larvae hatched in the rth survey period (/•) and 

associated standard errors (SE) used in estimating entrainment mortality for two analysis periods. 

a) Analysis Period 3: July 1, 1997-June 30, 1998 

Survey Start Date 

Jul 2-1, 1997 

Aug 25, 1997 

Sep 29, 1997 

Oct 20, 1997 

Nov 17, 1997 

Dec 10, 1997 

Jan 22, 1998 

Feb 26, 1998 

Mar 18, 1998 

Apr 15, 1998 

May 18, 1998 

Jun 8, 1998 

PE, 

0.0139 

0.0182 

0.859 

0.859 

0.00474 

0.859 

0.0143 

0 

0 

0.0556 

0.0323 

0.0467 

SE^PE,} 

0.00482 

0.00671 

0.288 

0.527 

0.00625 

0.911 

0.00760 

0 

0 

0.0201 

0.00894 

0.0132 

/ 

0.246 

0.0589 

0.0322 

0.00588 

0.00343 

0.00303 

0.0133 

0.00472 

0.00648 

0.216 

0.117 

0.293 

SE(J) 

0.00837 

0.00296 

0.00173 

0.000700 

0.000510 

0.000510 

0.00108 

0.000500 

0.000810 

0.0106 

0.00480 

0.00877 

b) Analysis Period 4: July 1, 1998-June 30, 1999 

Survey Start Date 

Jul 21, 

Aug 26, 

Sep 16, 

Oct 6, 

Nov 11, 

Dec 9, 

Jan 12, 

Feb 3, 

Mar 17, 

Apr 14, 

May 24, 

Jun 23, 

1998 

1998 

1998 

1998 

1998 

1998 

1999 

1999 

1999 

1999 

1999 

1999 

PE, 

0.0129 

0.00885 

0.00445 

0.0199 

0.0292 

0.00470 

0.0726 

0.0532 

0.123 

0.104 

0.0357 

0.150 

SE(PE,) 

0.00582 

0.00783 

0.00293 

0.0103 

0.0270 

0.00509 

0.0407 

0.0255 

0.0414 

0.0420 

0.00896 

0.0527 

f 

0.148 

0.00908 

0.00420 

.0.0148 

0.0160 

0.00375 

0.0257 

0.0439 

0.168 

0.251 

0.143 

0.173 

SE(J) 

0.0112 

0.00109 

0.000600 

0.00121 

0.00175 

0.000680 

0.00218 

0.00297 

0.00570 

0.00736 

0.00448 

0.00745 

TENERA E9-055.0 5-239 Final 316(b) Demonstration 

March 1.2000 
P.58 

5.2.6 Sculpins 

Table 5.2.6-8. Estimated total annual entrainment (ET ) and standard error 

(SE(ET)) for cabezon (Scorpaenichthys marmoratus) larvae from the three 

analysis periods. 

Analysis Period ET SE(ET) 

1) Oct 23, 1996-Sep 30, 1997 35,700,000 2,720,000 

2) Octl, 1997-Sep 30, 1998 14,700,000 1,460,000 

3) Jul 1, 1997-Jun 30, 1998 14,700,000 1,460,000 

Table 5.2.6-9. Estimated total annual adjusted entrainment (EAdj_T) and 

standard error (SE(EAdJ_T)) for cabezon (Scorpaenichthys marmoratus) 

larvae from the three analysis periods. 

Analysis Period EAdJ.T SE(EAdJ_T) 

1) Oct 23, 1996-Sep30, 1997 51,900,000 3,950,000 

2) Oct 1, 1997-Sep 30, 1998 36,300,000 3,600,000 

3) Jul 1, 1997-Jun 30, 1998 36,300,000 3,600,000 

TENERA E9-055.0 5-240 Final 316(b) Demonstration 

March 1,2000 
T- J 

_Pj5 ^ 

5.2.6 Sculpins 

Table 5.2.6-9. Cabezon (Scorpaenichthys marmoratus): Monthly estimates of proportional 

entrainment (PE,) and annual proportion of larvae hatched in the rth survey period (Jj) and 

associated standard errors (SE) used in estimating entrainment mortality for two analysis periods. 

a) Analysis Period 3: July 1, 1997-June 30, 1998 

Survey Start Date PE, SE (m f 

Jul 21, 1997 

Aug 25, 1997 

Sep 29, 1997 

Oct 20, 1997 

Nov 17, 1997 

Dec 10, 1997 

Jan 22, 1998 

Feb 26, 1998 

Mar 18, 1998 

Apr 15, 1998 

May 18, 1998 

Jun 8, 1998 

0 

0 

0 

0.106 

0.00608 

0.0140 

0.00317 

0 

0 

0 

0 

0 

0 

0 

0 

0.103 

0.00340 

0.00395 

0.00244 

0 

0 

0 

0 

0 

0 

0 

0 

0.0935 

0.0596 

0.289 

0.428 

0.108 

0.00924 

0.0107 

0.00280 

0 

b) Analysis Period 4: July 1, 1998-June 30, 1999 

Survey Start Date PE, SE(PE,) fi 

5E(f.) 

0 

0 

0 

0.00830 

0.00605 

0.0139 

0.0185 

0.00854 

0.00197 

0.00219 

0.00115 

0 

SE(J,) 

Jul 21, 

Aug 26, 

Sep 16, 

Oct 6, 

Nov 11, 

Dec 9, 

Jan 12, 

Feb 3, 

Mar 17, 

Apr 14, 

May 24, 

Jun 23, 

1998 

1998 

1998 

1998 

1998 

1998 

1999 

1999 

1999 

1999 

1999 

1999 

0 

0 

0 

0 

0 

0.00140 

0.00630 

0.00359 

0.00380 

0.00679 

0 

0 

0 

0 

0 

0 

0 

0.00072 

0.00209 

0.00127 

0.00181 

0.00774 

0 

0 

0 

0 

0 

0 

0 

0.104 

0.587 

0.177 

0.103 

0.028 

0 

0 

0 

0 

0 

0 

0 

0.00895 

0.0175 

0.0112 

0.00768 

0.00486 

0 

0 

TENERA E9-055.0 5-241 Final 316(b) Demonstration 

March 1,2000 
P.60 

5.2.6 Sculpins 

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Figure 5.2.6-1. Weekly mean larval density (#/m3 + 1 S.E.) at the DCPP intake. 

TENERA E9-055.0 5-242 Final 316(b) Demonstration 

March 1.2000 
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DCPP Intake 

Point San Luis 

Jul. 21,'97 Aug. 25,'97 Sep. 29,'97 Oct. 20,'97 Nov. 17,'97 Dec. 10,'97 

Figure 5.2.6-2a. Mean larval density (#/m3) collected in the DCPP study grid cells and at the entrainment sampling location. 

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TENERA E9-055.0 5-244 Final 316(b) Demonstration 

March 1,2000 
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Jul. 20, '98 Aug. 25, '98 Sep. 15, '98 Oct. 5, '98 Nov 10. '98 Dec. 8, '98 

Figure 5.2.6-2c (continued). Mean larval density (fl/m1) collected in the DCPP study grid cells and at the entrainment sampling location. 

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TENERA E9-055.0 5-246 Final 316(b) Demonstration 

March 1,2000 
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Figure 5.2.6-3. Length frequency of all measured larval fish collected in the entrainment 

samples. Minimum, median, mean, maximum, and central 98% ofthe larval lengths are noted. 

X-axis scale is not continuous at larger lengths. 

TENERA E9-055.0 5-247 Final 316(b) Demonstration 

March 1,2000 
P.66 

5.2.6 Sculpins 

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Median! Mean 

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Max 

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Max 

4.7 * •? 

Figure 5.2.6-4. Length frequency of measured fish from entrainment surveys that paired with 

grid surveys (both years combined). Minimum, median, mean, maximum, and central 98% ofthe 

larval lengths are noted. X-axis scale is not continuous at larger lengths. 

TENERA E9-055.0 5-248 Final 316(b) Demonstration 

March 1,2000 
P.67 

5.2.6 .Sculpins 

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Year 

I 

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Figure 5.2.6-5. Annual mean density +/- 2 standard errors (vertical lines) and grand mean 

density for all years combined (horizontal line) for the Intake Cove surface plankton tows. The 

annual mean densities are based on seven consecutive months ofdata (December through June) 

except for 1990, which had only five months (February through June). 

TENERA E9-055.0 5-249 Final 316(b) Demonstration 

March 1,2000 
P.68 

5.2.6 Sculpins 

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Analysis Period 4: Jul 1998-Jun 1999 

P a alongshor e 

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Sx 

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I T * km 

18x 

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3 4 7 km 

2 8 x 

4 3 * km 

SOx S21 km SBx 40x 

BOB km 88B km 

Slz a of Population Relative to Study Orld 

Equivalent Distanc e Alongshor e 

Figure 5.2.6-6a. Total annual entrainment mortality (P^) and 90% confidence interval (CI.) as 

a function ofthe reciprocal ofthe fraction ofthe population at risk and contained in the study grid 

(/£) used to approximate the alongshore extent ofthe study grid population expanded on the 

basis of alongshore current movements with the 90% C.I. indicated. 

TENERA E9-055.0 5-250 Final 316(b) Demonstration 

March 1.2000 
P.69 

5.2.6 Sculpins 

Smoothhead sculpin (Artedius lateralis) - maximum duration 

Analysis Period 3: Jul 1997-Jun 1998 

Estimate 

90% Cl. 

Ox Bx lO x 1Sx 20 x 2S x SOx 38 x 4Qx 

O k m 8 7 k m 17 4 k m 28 1 k m 34 7 k m 43 4 k m B2 1 k m 60 8 k m BSS k m 

Siz e o f Populatio n Relativ e t o Stud y Orl d 

Equivalen t Distanc e Alongshor e 

Smoothhead sculpin (Artedius lateralis) - maximum duration 

Analysis Period 4: Jul 1998-Jun 1999 

Estimate 

90% Cl. 

Ox 

O km 

Bx 

8 7 k m 

10x 1 Sx 20x 

174 k m 281 k m 347 k m 

2 Sx 

4 3 4 k m 

SOX 3Sx 40 x 

8 2 1 k m 80 8 k m 89 5 k m 

Siz e o f Populatio n Relativ e t o Stud y Orl d 

Equivalen t Distanc e Alongshor e 

Figure 5.2.6-6b. Total annual entrainment mortality (p^) and 90% confidence interval (C.I.) as 

a function ofthe reciprocal ofthe fraction ofthe population at risk and contained in the study grid 

(p.) used to approximate the alongshore extent ofthe study grid population expanded on the 

basis of alongshore current movements with the 90% C.I. indicated. 

TENERA E9-055.0 5-251 Final 316(b) Demonstration 

March 1,2000 
P.70 

5.2.6 Sculpins 

Figure 5.2.6-7. Mean number of sculpins (Cottidae) observed per 50-meter subtidal transect 

in the DCPP RWMP South Control area. Spline smoothing algorithm used to fit curve through 

points. 

TENERA E9-055.0 5-252 Final 316(b) Demonstration 

March 1,2000 
P.71 

5.2.6 Sculpins 

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Survey Date 

• designatessurveywithaensity=0 

Figure 5.2.6-8. Weekly mean larval density (#/m3 + I S.E.) at the DCPP intake. 

TENERA E9-055.0 5-253 Final 316(b) Demonstration 

March 1,2000 
H 

m 

z 

m £ 

m 

i o 

Ol 

Ol 

b 

3 

OJ 

2

 a 

D) 5 

§1 

IS) 3 

o a: 

s ° 

O 3 

Snubnose sculpin (Orthonopias triads) 

5-254 

CO 

E 

% 

0.90 

0.75 

0.60 

0.45 

0.30 

0.15 

0.00 

Depth Contours 

— — 20 meters 

• — 40 meters 

—•— 60 meters 

Point Buchon 

DCPP Intake 

Point San Luis 

Jul. 21,'97 Aug. 25,'97 Sep. 29,'97 Oct. 20.'97 Nov. 17.'97 Dec. 10.'97 

Figure 5.2.6-9a. Mean larval density (fV/m1) collected in the DCPP study grid cells and at the entrainment sampling location. 5' w 
m 

z 

m 

5 

m to * o 

Ol 

Ol 

Ol 

Ol 

3 

to 

20) ° (D 

" 3 

- » . OT 

ro 3 

o a-, 

o o 

o 3 

Snubnose sculpin (Orthonopias triacis) 

CO 

0.90 

0.75 

0.60 

0.45 

0.30 

0.15 

0.00 

Depth Contours 

i" 20 meters 

• — • 40 meters 

- ^ — 60 meters 

Point Buchon 

DCPP Intake 

Point San Luis 

Jan. 22, "98 Feb. 26,'98 Mar. 18,'98 Apr. 15,'98 May 18,'98 Jun. 8,'98 

Figure 5.2.6-9b (continued). Mean larval density (tf/m1) collected in the DCPP study grid cells and at the entrainment sampling location. 

Ul 

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b> 

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m 

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b 

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w 

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Snubnose sculpin (Orthonopias triacis) 

CO 

0.90 

0.75 

0.60 

0.45 

0.30 

0.15 

0.00 

Depth Contours 

— —• 20 meters 

mmmm• 40 meters 

^•a a 60 meters 

Point Buchon 

DCPP Intake 

Point San Luis 

Jul. 20.'98 Aug. 25,'98 Sep. 15,'98 Oct. 5, "98 Nov 10,'98 Dec. 8,'98 

Figure 5.2.6-9c (continued). Mean larval density (#/m}) collected in the DCPP study grid cells and at the entrainment sampling location. 

Ul 

co 

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m 

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o 

cn 

cn 

to 

Ul 

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91 

co 

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2 ° to § l l 

-k w 

ro u 

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o o 

O 3 

Snubnose sculpin (Orthonopias triacis) 

CO 

E 

0.90 

0.75 

0.60 

0.45 

0.30 

0.15 

0.00 

Depth Contours 

<—— 20 meters 

• — 40 meters 

• — 60 meters 

Point Buchon 

DCPP Intake 

Point San Luis 

Jan. 11. '99 Feb. 2, '99 Mar. 16, '99 Apr. 13, '99 May 23. "99 Jun 22, 99 

Figure 5.2.6-9d (continued). Mean larval density (#/m3) collected in the DCPP study grid cells and at the entrainment sampling location. 

Ul 

to 

b> 

co 

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c_ 

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5'. in 

cn 
P.76 

5.2.6 Sculpins 

cu 

o 

c 

g 3 

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>» 

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c 

0) 

3 

cr 

cu 

c 

8 •• 

cu 

0. 

Snubnose sculpin (Orthonopias triacis) 

N= 3,750 

- T— 

•lllm 

1.6 2.1 2.6 3.1 3.6 4.1 4.6 S.l S. 6 *+•*<*» 

wW* 111 

Length Category (mm) 

i • • • i • ' • i ' ' ' i ' • ' i ' ' ' i • ' ' i • • • i • • ' i • • • i • n— r 

O 4 8 1 2 1 6 2 0 • 2 4 2 8 3 2 3 6 

Estimated age (days) 

Figure 5.2.6-10. Length frequency of all measured larval fish collected in the entrainment 

samples. Minimum, median, mean, maximum, and central 98% ofthe larval lengths are noted. 

X-axis scale is not continuous at larger lengths. 

TENERA E9-055.0 5-258 Final 316(b) Demonstration 

March 1,2000 
r 

5.2.6 Sculpins 

UJ 

co 

E 

iE. 

$ 

c 

a> 

Q 

rz 

ro 

cu 

20—I 

15" 

10" 

CU 

O 

c 

cu 

"»- 5 — 

Min 

1% 

cr 

CD 

20—I 

15 — 

c 

cu 10 -

o 

cu 

a. 

Min 

1% 

Snubnose sculpin (Orthonopias triacis) 

Entrainment: N=380 

Median! Mean 

Median 

Grid: N=161 

Mean 

Length Category (mm) 

99% 

Max 

99% 

ill 

Max 

sit) <? <• *r 

Figure 5.2.6-11. Length frequency of measured fish from entrainment surveys that paired with 

grid surveys (both years combined). Minimum, median, mean, maximum, and central 98% ofthe 

larval lengths are noted. X-axis scale is not continuous at larger lengths. 

TENERA E9-055.0 5-259 Final 316(b) Demonstration 

March 1.2000 
P.78 

5.2.6 Sculpins 

UJ 

CO 

1 

+ 

E sity (# 

c Mea

n De 

0.12 — 

0.11 —I 

0.10 — 

0.09 -3 

~ 

0.08 — 

0.07-r 

0.06 — 

0.05-: 

- 0.04 — 

0.03 -E 

0.02 ~ 

0.01 ~ 

o.oo — 

Snubnose sculpin (Orthonopias triacis) 

I 

A 

I > I 

IIIII I 

1990 1991 1992 1993 1994 1995 

Year 

I 

i 

1996 

i 

i 

1997 • 

I 

i 

1998 

Figure 5.2.6-12. Annual mean density +/- 2 standard errors (vertical lines) and grand mean 

density for all years combined (horizontal line) for the Intake Cove surface plankton tows. The 

annual mean densities are based on seven consecutive months ofdata (December through June) 

except for 1990, which had only five months (February through June). 

TENERA E9-055.0 5-260 Final 316(b) Demonstration 

March 1,2000 
. ••" ' • 1 V 

P.79 

5.2.6 Sculpins 

1.20 -

1.08 -

o.seo.B4 -

0.72 ~ 

JjC o.eo -

0.4 8 ~ 

O.SB -

0.2.4 -

0.12 -

O.OO — 

Snubnose sculpin (Orthonopias triacis] - mean duration 

Analysis Period 3: Jul 1997-Jun 1998 

P s alongahor a 

\ \ 

\ 

! 

-y "r*"-

—i—I—I—i— i 

Densit y 

Extrapolate d P s 

Estimate 

90% Cl. 

J>*f = 0.102 

^^Pu- 0.0361 ±0.113 

r—i—i—i i i i i i r i i i i i i i i i 1—1—1—1—|—1—1—1—1—|—r —1—1—1—r1 

Ox 

O k m 

Bx 

ar km 1 0 x 

1 7 4 K m 

1 5 x 

2 8 1 km 

2 Ox 

3 4 7 k m 

2 B x 

4 3 4 k m 

SOx 

B 2 1 k m 

3 Sx 

BOS k m 

4 0 x 

BSS k m 

S i a » o f Populatio n Relativ e t o Stud y Orl d 

Equivalen t Distanc e Alongahor a 

Snubnose sculpin (Orthonopias triacis) - mean duration 

Analysis Period 4: Jul 1998-Jun 1999 

Estimate 

90% Cl. 

Pu = 0.202 

PAI = 0.121 ±0.182 

2 0 x 

3 4 7 k m 

2 B x 

4 3 4 k m 

SOx 

S 2 1 k m 

3Bx 

BOB k m 

4 0 x 

B 8S k m 

Siz e o f Populatio n Relativ e t o Stud y Orl d 

Equivalen t Distanc e Alongshor e 

Figure 5.2.6-13a. Total annual entrainment mortality (P^) and 90% confidence interval (CI.) as 

a function ofthe reciprocal ofthe fraction ofthe population at risk and contained in the study grid 

(P.) used to approximate the alongshore extent ofthe study grid population expanded on the 

basis of alongshore current movements and the offshore extrapolation of study grid abundance 

extended alongshore using bodi onshore and alongshore current movements with 90% CI.'s 

indicated. 

TENERA E9-055.0 5-261 Final 316(b) Demonstration 

March 1,2000 
P.80 

5.2.6 Sculpins 

Snubnose sculpin (Orthonopias triads) - maximum duration 

Analysis Period 3: Jul 1997-Jun 1998 

— Estimate 

— 90% Cl. 

Densit y 

Extrapolate d P s 

Pu- 0.0231 ±0.0883 

Ox 

O k m 

Sx 

8 7 k m 

1Ox 16 x 20 x 2B x 

1 7 4 k m 28 1 k m • 34 7 k m 43 4 k m 

30x 

S21 km 

38x 40x 

BOB km BBS km 

S i a • o f Populatio n Relativ e t o 8tud y Orl d 

Equivalen t Distanc e Alongahor a 

Snubnose sculpin (Orthonopias triacis) - maximum duration 

Analysis Period 4: Jul 1998-Jun 1999 

Density Extrapolated Ps off scale 

1/Ps = 55.8 

Pu = 0.0210 ±0.0413 

Estimate 

90% Cl. 

Sx 

8 7 k m 

1 0 x 

1 7 4 k m 

1 Sx 20 x 

2 6 1 k m 34 7 k m 

2 B x 

4 3 4 k m 

SOx 

S 2 1 k m 

SSx 40 x 

BOB k m BBS k m 

Slare o f Populatio n Relativ e t o Stud y Oli d 

Equlvelen t Olatano e Alongahor a 

Figure 5.2.6-13b. Total annual entrainment mortality (pu ) and 90% confidence interval (CI.) 

as a function ofthe reciprocal ofthe fraction ofthe population at risk and contained in the study 

grid (/£) used to approximate the alongshore extent ofthe study grid population expanded on the 

basis of alongshore current movements and the offshore extrapolation of study grid abundance 

extended alongshore using both onshore and alongshore current movements with 90% C.I.'s 

indicated. 

TENERA E9-055.0 5-262 Final 316(b) Demonstration 

March 1.2000 
r f • T 

5.2.6 Sculpins 

transect i #/50-meter mear 

1.2 

1.1 

1.0 

0.9 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.11 

0.0 

at 

• s 

• w 

al^ar^BB 

• aal n • 

iiili i 

78 80 82 

• 

• 

• 

• 

• 

• 

• • 

• 

84 

\ B • ^^^^ \ • 

• • • • ^s . • • 

>• • • • \ 

• • • m rn. 

IIIIIIIII I 

86 88 90 92 94 

Plant Start-up 

Year 

• • 

96 

• 

• • • 

98 

Figure 5.2.6-14. Mean number of snubnose sculpins observed per 5 0-meter subtidal 

transect in the DCPP RWMP South Control area. Spline smoothing algorithm used to fit 

curve through points. 

TENERA E9-055.0 5-263 Final 316(b) Demonstration 

March 1,2000 
P.82 

5.2.6 Sculpins 

0.10" 

0.09 -

UJ 

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+ 

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-

0.07 -

-

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0.05 -

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0.04 -

-

0.03 -

0.02 -

0.01 -

o.oo - II. 

Cabezon (Scorpaenichthys marmoratus) 

U, rirmtmimiimifiH 

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Survey Date 

T aesignatassurvey with density =0 

Figure 5.2.6-15. Weekly mean larval density (#/m3 + 1 S.E.) at the DCPP intake. 

TENERA E9-055.0 5-264 Final 316(b) Demonstration 

March 1.2000 
H 

m 

z 

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Cabezon (Scorpaenichthys marmoratus) 

co E 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

0.0 

Depth Contours 

— — 20 metets 

— — 40 meters 

^ — 60 meters 

Point Buchon 

DCPP Intake 

Point San Luis 

Jul. 21,'97 Aug. 25,'97 Sep. 29, "97 Oct. 20,'97 Nov. 17,'97 Dec. 10.'97 

Figure 5.2.6-16a. Mean larval density (#/m*) collected in the DCPP study grid cells and at the entrainment sampling location. 

Ul 

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TENERA E9-055.0 5-266 Final 316(b) Demonstration 

March 1.2000 
m 

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CO J: 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

0.0 

Depth Contours 

»'i 20 meters 

•• 40 meters 

^ — 60 meters 

Point Buchon 

DCPP Intake 

Point San Luis 

Jul. 20, '98 Aug. 25, "98 Sep. 15, '98 Oct. 5. '98 Nov 10. '98 Dec. 8, "98 

Figure 5.2.6-16c (continued). Mean larval density (#/m3) collected in the DCPP study grid cells and at the entrainment sampling location. 
P.86 

5.2.6 Sculp'ns 

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TENERA E9-055.0 5-268 Final 316(b) Demonstration 

March 1,2000 
r ,.. . , 

5.2.6 Sculpins 

Occurrence 

o Frequency Percent 

Cabezon (Scorpaenichthys marmoratus) 

N= 1,537 

10 — lll l 

s — IIIIII I 

M i n 

Media n 

1«X> 

ill <-> 1 1 1 1 1 

2 . 2 2. T 3. 2 3. 7 A.Z A.' 

L 

c 

Moa n 

9 9 % 

||1| 

r S. 2 5. 7 6. 2 6. 7 

ength Category (mm) 

•IIII I 

3 2 A e O I O 

Estimated age (days) 

M a x 

' VJlr 

1 1 1 

Figure 5.2.6-17. Length frequency of all measured larval fish collected in the entrainment 

samples. Minimum, median, mean, maximum, and central 98% ofthe larval lengths are noted. 

X-axis scale is not continuous at larger lengths. 

I 

TENERA E9-055.0 5-269 Final 316(b) Demonstration 

March 1.2000 
P.88 

5.2.6 Sculpins 

Cabezon (Scorpaenichthys marmoratus) 

15-

- Min 

10" 

co 

1 % 

Entrainment: N=104 

Mean Median 

II u 

99% 

Max 

2.8 3.3 . 3.8 4.3 4.8 

ll I ' ' ' ' I H I 

5.3 5.8 6.3 6.8 v-W 

Grid: N=s705 

15—I 

CD 

C 

CO 

o 

t_. 

CD 

1 0 — 

Min 

IIIII I 

1% 

+|UP 

Median Mean 

99% 

*ul • # i i i1^-'• • * i I ?T T 

2.8 3.3 3.8 4.3 4.8 5.fc 3 5.8 6.3 6.8 ""^ 

LL 

Max 

Length Category (mm) 

Figure 5.2.6-18. Length frequency of measured fish from entrainment surveys that paired with 

grid surveys (both years combined). Minimum, median, mean, maximum, and central 98% ofthe 

larval lengths are noted. X-axis scale is not continuous at larger lengths. 

TENERA E9-055.0 5-270 Final 316(b) Demonstration 

March 1.2000 
P.89 

r 

5.2.6 Sculpins 

-•— * 

UJ 

CO 

1 

+ 

E 

2§. 

i > 

CO 

c CD 

O Mean

0.048 — 

0.044 ~E 

' 0.040 -E 

0.036 ~E 

0.032 — 

z. 

0.028 — 

0.024 — 

-

0.020 — 

-

0.016 ~L, 

0.012 — 

0.008 -E 

0.004-E 

p.ooo —' 

1 

Cabezon (Scorpaenichthys marmoratus) 

j 

: . . . -

* 

, I 

IIIII I 

990 1991 1992 1993 1994 1995 

Year 

I 

I 

1996 

I 

I 

1997 

r

. 

1 

i 

199£ I 

Figure 5.2.6-19. Annual mean density +/- 2 standard errors (vertical lines) and grand mean 

density for all years combined (horizontal line) for the Intake Cove surface plankton tows. The 

annual mean densities are based on seven consecutive months ofdata (December through June) 

except for 1990, which had only five months (February through June). 

1 

I 

TENERA E9-055.0 5-271 Final 316(b) Demonstration 

March 1,2000 
5.2.6 Sculping 

P.90 

Cabezon (Scorpaenichthys marmoratus) - mean duration 

Analysis Period 3: Jul 1997-Jun 1998 

90% Cl. 

r—|—i—i—i—i—|—i—i—i — 

Ox 6>x 10 x IB x 20 x 25 x SOx 3B x 40 x 

O k m ST k m 17 4 k m 20 1 k m 3* 7 k m 43 4 k m S2 1 k m SOB k m 6B 6 k m 

Six * o f Populatio n Relativ e t o Stud y Orl d 

Equivalen t Distanc e Alongahor a 

Cabezon (Scorpaenichthys marmoratus) - mean duration 

F»s alonoahor* 

Analysis Period 4: Jul 1998-Jun 1999 

Estimate 

90% Cl. 

P/u = 0.0140 

Pu - 0.00835 ± 0.0403 

-I Ox IB x 

1 7 4 k m 2B 1 k m 

2 0 x 2S x 

3 4 7 k m 43 4 k m 

SOx 

S 2 1 k m 

3 Sx 40 x 

aoa km aes km 

Slz a of Ropulatlon Relative t o Study Orld 

Equivalent Distanc e Alongshor e 

Figure 5.2.6-20a. Total annual entrainment mortality (P^) and 90% confidence interval (CI.) as 

a function ofthe reciprocal ofthe fraction ofthe population at risk and contained in the study grid 

(p~s) used to approximate the alongshore extent ofthe study grid population expanded on the 

basis of alongshore current movements and the offshore extrapolation of study grid abundance 

extended alongshore using both onshore and alongshore current movements with 90% C.I.'s 

indicated. 

TENERA E9-055.0 W72 Final 316(b) Demonstration 

March 1.2000 
P.91 

S.2.6 Sculpins 

Cabezon (Scorpaenichthys marmoratus) - maximum duration 

Analysis Period 3: Jul 1997-Jun 1998 

Rs alongshore 

Estimate 

— 90% Cl. 

Density 

Extrapolated Rs 

?u = 0.00569 ± 0.0456 

Ox 

O km 

Sx 

87 km 

i i i i i i i i 

lOx IBx 20x 28x 30x 35x 40x 

174 km 281 km 347 km 434 km 821 km 808 km 888 km 

S i a » of Ropulatlon Relative to Study Grid 

Equivalent Distanc e Alongshor e 

Cabezon (Scorpaenichthys marmoratus) - maximum duration 

Analysis Period 4: Jul 1998-Jun 1999 

Estimate 

90% Cl. 

Siz e of Ropulatlon Relative to Study Orld 

Equivalent Distance Alongshore 

Figure 5.2.6-20b. Total annual entrainment mortality (pu ) and 90% confidence interval (CI.) 

as a function ofthe reciprocal ofthe fraction ofthe population at risk and contained in the study 

grid (p.) used to approximate the alongshore extent ofthe study grid population expanded on the 

basis of alongshore current movements and the offshore extrapolation of study grid abundance 

extended alongshore using both onshore and alongshore current movements with 90% C.I.'s 

indicated. 

I 

TENERA E9-055.0 5-273 Final 316(b) Demonstration 

March 1.2000 
5.2.6 Sculpins 

a) 

b) 

Cabezon (Scorpaenichthys marmoratus) 

Landings from the Morro Bay Area 

w 

O) 

_c 

TJ 

e 

80 

70 

60 

50 4 

40 

30 4 

20 -

QMorro Bay 

• Port San Luis 

CO CO CO CO 

- J - J ^J CD 

CJI ^ 1 CO - » 8 (O 

Uol o 

CO 

CB 

•si 

CO 

0» 

CO 

CO 

CO 

CO 

CO 

w 

CO 

CO 

cn 

CO 

-cJ o 

Year 

o 

cu 

CA 

c 

CO 

0) 

0) 

E 

I 

o 

c 

CO 

CD 

E 

Figure 5.2.6-21. Yearly abundance of cabezon measured by two independent methods: 

a) Commercial landings of adults from Morro Bay area and, b) Mean number of adults and 

juveniles observed per 50-meter subtidal benthic transect in the DCPP RWMP South Control 

area. Spline smoothing algorithm used to fit curve through points. 

TENERA E9-055.0 5-274 Final 316(b) Demonstration 

March 1.2000 
r 

5.2.7 White Croaker 

5.2.7 Assessment of White Croaker (Genyonemus lineatus) 

Genyonemus lineatus (Ayres 1855); white croaker; length to 41 cm; Barkley 

Sound, British Columbia to Bahia Magdalena, southern Baja California; 

inshore to 236 m; incandescent brownish to yellowish on back, silver below; 

fins yellow to white (Miller and Lea 1972; Eschmeyer et al. 1983). 

White croaker is one of eight species in the family Sciaenidae (the drums) occurring in California 

coastal waters. Other representatives of this family are white seabass (Atractoscion nobilis), 

shortfin corvina (Cynoscion parvipinnis), black croaker (Cheilotrema saturnum), spotfin croaker 

(Roncador stearnsi), Califomia corbina (Menticirrhus undulatus), queenfish (Seriphus politus), 

and yellowfin croaker (Umbrina roncador). Two ofthese, shortfin corvina and black croaker, are 

neither commercially nor recreationally important fishes in California. 

White croaker are most abundant in southern and central California at depths from 6 m to 75 m 

(Love 1996). They tend to form schools, often over sand or mud bottoms. White croaker spawn 

year-round in central California. Love et al. (1984) state that 

I 

I 

1 

Batch fecundities ranged from 800 eggs in a 15.5 cm long female to 37,200 eggs in a 

26 cm long female. During the spawning period about 19% of all mature female white 

croaker sampled contained hydrated eggs, implying that a female spawned about once 

every 5 d. Females of ages 1 and 2 (13-18 cm) have a spawning season of 3 mo and 

spawn about 18 times per season, whereas older fish (19 cm and larger) spawn over a 

period of 4 mo, about 24 times per season. 

Love et al. (1984) also indicate that eggs and larvae are pelagic, and post-flexion larvae settle to 

the bottom as they develop. Juveniles are found near the bottom in 3-6 m of water, then migrate 

to deeper water as they mature. By one year after settlement, half of all male and female white 

TENERA E9-055.0 5-275 Final 316(b) Demonstration 

March 1,2000 
P.94 

5.2.7 White Croaker 

croaker are reproductively mature, with 100% cohort maturity attained by the third to fourth year. 

White croakers live 12-13 yr. 

Studies conducted at the San Onofre Nuclear Generating Station (SONGS) provided estimates of 

adult equivalent losses for white croaker that were entrained and impinged by the cooling water 

intake system (Murdoch et al. 1989). They estimated the duration ofeach larval stage (e.g., yolksac, pre-flexion, flexion, post-flexion) at risk by dividing the range in body length ofa larva in a 

given stage by the estimated daily growth rate of 0.20 mm/d (Murdoch et al. 1989). This method 

assumed linear growth rates throughout the larval stages. In the present study we used the same 

growth rate with the same assumption. 

5.2.8.1 Summary of Field Collections 

White croaker larvae were found seasonally at the DCPP intake structure during the years 1996-

1999, with their highest densities occurring during the winter and spring (Appendix H). There 

were 4,300 larval white croaker identified from 1,114 bongo net subsamples collected at the 

DCPP intake structure between October 1996 and June 1999 representing 24% ofthe subsamples 

collected and processed from that location during that period. The highest densities of larval 

croaker occurred in March 1997 and May 1998 (Figure 5.2.7-1). The density of this species was 

variable between weeks, with one or two weeks of rather high density followed by several 

consecutive weeks of lower density. The highest entrainment densities of white croaker larvae in 

1998 occurred in May, while only a few were seen during that month in 1997. This shift in 

abundance peaks between years may have been affected by the El Nino event that began during 

the fall/winter season of 1997-98 (Lynn et al. 1998; NOAA 1999). 

White croaker larvae generally occurred in the DCPP study grid during December through May 

ofeach year (Appendix H), with their highest recorded abundance occurring during March 1998 

(Figure 5.2.7-2). When present, the highest white croaker larval densities occurred in the 

southern half of the nearshore grid sampling area. There were 1,710 larval white croaker 

identified from 422 bongo net subsamples representing 14% ofthe study grid subsamples 

collected and processed from July 1997-June 1999. 

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Standard lengths of all white croaker larvae collected at the DCPP intake structure between 

October 1996 and June 1999 ranged from a minimum of 0.90 mm to a maximum of 8.2 mm 

(Figure 5.2.7-3). The central 98% of this length-frequency distribution resulted in minimum and 

maximum lengths for the analyses of 1.1 mm and 5.5 mm, respectively. The mean larval length 

in this distribution was 2.4 mm. Hatching size for white croaker is reported between 1.5 and 1.8 

mm (Moser 1996). The fact that we observed larvae smaller than the reported hatching lengths 

can be explained by natural variation of hatch lengths within the population and by the 

phenomenon of shrinkage following preservation (Theilacker 1980). 

The growth rate of larval white croaker (0.20 mm/d) reported by Murdoch et al. (1989) was used 

to estimate ages of entrained larvae. Assuming that the shortest larvae were immediately posthatch and aged zero days, then the estimated ages of larvae entrained could have ranged from 

zero days up to 22-37 d post-hatching for the longest larvae measured. On average, the estimated 

ages of white croaker larvae entrained at DCPP ranged from 7-8 d post-hatching. 

Differences between the distributions of white croaker larval lengths at the DCPP intake structure 

and the study grid (Figure 5.2.7-4) were tested using a Kolmogorov-Smirnov test. The test 

detected a significant difference between the two distributions (p < 0.001). The largest difference 

between the distributions was detected at a length of approximately 2.7 mm, the size separating 

two modes ofthe distribution from the DCPP intake. A single mode predominated in the study 

grid distribution. A t-test also detected a significant difference (p < 0.001) between the mean 

lengths for the two locations: 2.7 mm at the DCPP intake and 2.3 mm in the study grid. 

Differences in the mean are partly due to a larger differences in sample size between the study 

grid (n= 1,263) and the intake location (n=150). A large sample size also causes the /-test to be 

highly sensitive to small differences between the means (Zar 1984). The length frequency of 

white croaker (n=3,529) in all entrainment subsamples (Figure 5.2.7-3) yielded a distribution 

similar to that ofthe nearshore grid subsamples. While these differences were statistically 

detectable and significant, both distributions were heavily weighted with recently hatched (yolksac) and pre-flexion larvae. Therefore, we believe that the entrainment subsamples and grid 

subsamples represent the same population of available larvae. 

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5.2.7 White Croaker 

5.2.7.2 Estimating Total Annual Entrainment 

The annual estimated mean entrainment white croaker larvae ranged from a minimum of 

65,100,000 (SE =3,880,000) in Analysis Period 2 to a maximum of 70,500,000 (SE =2,620,000) 

in Analysis Period 1 (Table 5.2.7-1). A 95% confidence interval around these estimates 

approximated by 2 • SE(ET) does not overlap indicating that the estimates were probably not 

statistically different. 

Annual estimates ofthe number of white croaker larvae entrained, adjusted to a long-term mean 

based on annual indices using weekly Intake Cove surface plankton tows (Figure 5.2.7-5), 

ranged from a minimum of 305,000,000 (SE =11,300,000) in Analysis Period 1 to a maximum of 

447,000,000 (SE =26,300,000) in Analysis Period 3 (table 5.2.7-2). The average index for the 

years 1997 and 1998 are 0.0251 larvae/m^ and 0.0161 larvae/m^, respectively, while the longterm average index is 0.109 larvae/m^ forthe years 1990-1998, yielding the ratio III, of 4.33 

for 1997 and 6.77 for 1998. The adjustment increases the difference between the estimates. A 

95% confidence interval, approximated by 2-SE(EMJ-T) would show a statistically significant 

difference between the 1996-1997 estimates and the two 1997-1998 estimates. 

5.2.7.3 Fecundity Hindcasting (FH) 

Fecundity hindcasting requires age-specific fecundity and mortality to assess entrainment effects. 

White croaker spawn multiple times within a year. Females of 1-2 yr (i.e., 13-18 cm) undergo a 

3 mo spawning season and spawn ca. 18 times per season. Older fish (i.e., 19 cm and larger) 

spawn over a period of 4 mo, ca. 24 times per season (Love et al. 1984). In our calculations we 

will assume an average of 21 egg batches per yr. The average number of eggs per batch will be 

based on Love et al. (1984) who showed a modal age of 3 yr for fish lengths of 18-18.9 cm. This 

permits extrapolation to a batch fecundity of approximately 5,000 eggs for age 3 yr. 

Love et al. (1984) found that adult white croaker have a maximum longevity of 12 yr, and Love 

(1996) stated that the species matures between 1 and 4 yr, with half spawning after 1 yr. The 

expected average age of maturation for the purpose of calculations was estimated as 2 yr. 

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Love (1996) reported that white croaker eggs hatch in 2 d, while Murdoch et al. (1989) suggested 

an instantaneous egg mortality rate of Z = 0.25 (survival «78%/day). Egg survival can therefore 

be estimated as 

SEgg=e2l0-

2S) =0.6065. 

An estimate of survival for larvae from the time of egg hatching to entrainment was based on 

information on larval lengths collected from DCPP entrainment subsamples. The central 98% 

lengths ofthe larvae ranged from 1.1-5.5 mm with a mean of 2.44 mm. Murdoch et al. (1989) 

states that white croaker larvae grow at a rate of approximately 0.2 mm per day. The average 

time to entrainment from hatching (hatch length is assumed to be the shortest length recorded in 

DCPP subsamples) is then estimated as 6.7 d. Assuming that the instantaneous larval survival 

rate is the same as for eggs, larval survival is estimated as 

SLanm=e^i°

2i) =0.1873. 

It is likely that the larval survival rate is equal to or greater than the survival rate of eggs. Thus, 

the survival rate for larvae is probably underestimated, resulting in an overestimate bf FH. 

As an example ofthe /"//calculation, when these parameters are modeled for the period October 

1, 1997 through September 30, 1998, the resulting number of adult females that would have 

produced the number of entrained larvae is given as 

440,198,000 

12-2 FH = : - /t „ . = 7,380 adult females per yr. 

(0.6065)(0.1873)(5,000-21) 

Estimates of FH were different between the two years of sampling (Table 5.2.7-3). Numbers of 

hindcast adult females from the three analysis periods ranged from 5,000-7,500. The least 

number of hindcast individuals were estimated from Analysis Period 1 (October 1996-September 

1997) while the greatest were estimated from Analysis Period 3 (July 1997-June 1998). 

Sensitivity Analysis 

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5.2.7 White Croaker 

Longevity had the greatest leverage on recalculated values of FH (Table 5.2.7-4). Varying this 

parameter in the model resulted in an FH range of 2,320-237,000 adult females for the three 

periods, compared to the original estimate of 5,110-7,500 adult females. Survivorship had the 

next greatest amount of leverage on recalculated FH. 

5.2.7.4 Adult Equivalent Loss (AEL) 

For white croaker, no independent estimate of survival from entrainment to age of adult 

recruitment was found in the literature. To calculate AEL as 2 • FH, we must first align the ages 

at maturity (~5 yr) and recruitment into the fishery (3-4 yr) so that the FH females are ofthe 

same age as the AEL recruits. As such, AEL ranged from 14,700 to 21,600 adult white croaker 

per year across the three analysis periods. 

5.2.7.5 Empirical Transport Model (ETM) 

Monthly estimates of proportional entrainment (PE,) in each rth survey from the two years 

sampled ranged from a minimum of zero to a maximum of 0.0340±0.008 (±\SE(PE, 1) in 

January 1998 (Table 5.2.7-5). No larvae were collected at either the DCPP intake or from the 

study grid when both PE, and the proportion of larvae present in the rth survey period (Jj) were 

equal to zero (e.g., August-November 1998 and April-June 1999). When PE, =0 and J>0, 

larvae were collected at the DCPP intake during the survey period but not during the entrainment 

survey paired with the 72-hour study grid survey. Since PE, was weighted by Jj , some ofthe 

larger PE, values were less important to the annual estimate of entrainment mortality. 

The lengths of entrained white croaker larvae, excluding the largest 1% and smallest 1% of all 

measurements, ranged from 1.1 to 5.5 mm. Assuming a growth rate of 0.2 mm/day (Murdoch et 

al. 1989), larvae may be susceptible to entrainment by the plant for approximately 22 days. The 

frequent, repeated breeding of white croaker suggests that the entrainment at Diablo Canyon 

occurs over multiple larval batches. Literature on the life history of white croaker would support 

this contention (Love et al. 1984; Love 1996). 

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Estimates of PM differed markedly when calculated using the mean and maximum larval 

durations and were generally higher during the second year of sampling (Figures 5.2.7-6). The 

larval durations calculated using the mean and maximum larval lengths differed by 15 d (7 vs. 22 

d). For /s calculated using only alongshore currents, differences in duration did not cause much 

change in PM between mean and maximum duration; ca. 2-3% in Analysis Period 3 and ca. 4-

6% in Analysis Period 4. Although white croaker larvae were more common in the southern half 

ofthe study grid when they were abundant (March 1998), they generally occurred throughout the 

study grid and were not restricted to the nearshore grid cells. Therefore, Ps was calculated using 

both alongshore current movement and extrapolating study grid abundance offshore based on 

onshore current movement. For Ps calculated using alongshore currents and offshore abundance 

extrapolation, changing larval duration did not change PM much in Analysis Period 3 (ca. 0.1-

0.3% for both durations), but yielded a change from 2% (mean duration) to 1% (maximum 

duration) in Analysis Period 4. 

5.2.7.6 Interpretation of Assessment Results 

White croaker have both commercial and recreational fishery value. Love et al. (1984) stated that 

fishing for white croaker in Monterey Bay occurs on a daily basis year round. The daily catch can 

range from 400-900 kg (ca. 0.4-0.9 MT) with a maximum catch of 1,800 kg (ca. 1.8 MT) of 

white croaker. The annual harvest of white croaker in Monterey Bay can then be estimated at 

approximately 248 MT. However, available evidence suggests that commercial catches of white 

croaker have been declining since around 1985 in the Monterey Bay area (Starr et al. 1998). 

Payment to the fishermen in 1990 was ca. $0.19/kg depending on catch size and fish condition 

(Leet et al. 1992). The total recreational catch in both northern and southern California in 1998 

was estimated at 443,000 fishes (PSMFC RecFIN database). Data from the California 

Department of Fish & Game show that local commercial landings of white croaker during the 

period 1975-1998 averaged 9.1 MT at Port San Luis and 3.8 MT at Morro Bay (Figure 5.2.7-7). 

Because ofthe low economic value ofthe species in comparison to other targeted species, some 

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5.2.7 White Croaker 

ofthe white croaker landings probably represent incidental catches as a result ofthese other 

fisheries. 

Love et al. (1984) gives the length mode for white croaker caught in the commercial gillnet 

fishery (28 cm SL) and from skiff sportfishing (22.5 cm SL). The weight ofa 28 cm white 

croaker is approximately 200-225 g, depending on gender, with females generally heavier. 

Assuming a daily natural mortality rate of 0.0005 (Ricker 1975), we can align the approximately 

5-yr old /"//females to an age of recruitment to the fishery of 3.5 yr (Love et al. 1984). In this 

manner, assuming a 50:50 sex ratio in the population, 2 • FH becomes equivalent to AEL. Thus, 

the approximate AEL based on ///ranged from 14,700 3.5-yr old adults in 1996-1997 to a 

maximum of 21,600 in 1997-1998. Using an average weight of 0.213 kg/adult in the fishery 

derived from Love et al. (1984), the price per kg from Leet et al. (1992), and assuming 100% 

catchability^ these equivalent adult losses could equate to 3.1-4.6 MT annually, approximately 

$594-872/yr. Alternatively, this conservative estimate of loss represents 24-36% ofthe average 

annual catch from the Morro Bay area between 1975-1998. However, estimates of annual 

proportional larval entrainment mortality (PM ) that assume no compensation, suggest losses of 

0.1% to perhaps as high as 6% ofthe local population (over areas 4-41 times the study grid area), 

providing a lower limit to these proportional effects. 

Adult white croaker are widely distributed over sand and mud bottoms in shelf waters and are not 

typically found in association with rock substratum. Combining this fact with the fact that white 

croaker adults are rarely observed in the vicinity ofthe power piant (Tenera 1997c) leads to the 

conclusion that their abundance is centered elsewhere than around Diablo Canyon. Therefore, the 

greater abundance of soft bottom habitat relative to rock substrata in the Morro Bay and Avila 

areas, combined with relatively low larval mortality probabilities of PM (0.001-0.06), suggests 

that entrainment impacts on local white croaker populations are not appreciable. 

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