p.1 

5.2.7 White Croaker 

Table 5.2.7-1. Estimated total annual entrainment (Er ) and standard error 

(SE(ET)) for white croaker (Genyonemus lineatus) larvae from the three 

analysis periods. 

Analysis Period PT SE(ET) 

1) Oct 23, 1996-Sep30, 1997 70,500,000 

2) Oct 1, 1997-Sep 30, 1998 65,100,000 

3) Jul 1, 1997-Jun 30, 1998 66,100,000 

2,620,000 

3,880,000 

3,890,000 

Table 5.2.7-2. Estimated total annual adjusted entrainment (PAdj_T ) and 

standard error (SE(PAdJ_T)) for white croaker (Genyonemus lineatus) larvae 

from the three analysis periods. 

Analysis Period 'Adj-T 

.1) Oct 23, 1996-Sep 30, 1997 305,000,000 

2) Oct 1, 1997-Sep 30, 1998 440,000,000 

3) Jul 1, 1997-Jun 30, 1998 447,000,000 

SP(PAJi-r) 

11,300,000 

26,300,000 

26,300,000 

I 

I 

I 

TENERA E9-055.0 5-283 Final 316(b) Demonstration 

March 1,2000 
P.2 

5.2.7 White Croaker 

Table 5.2.7-3. Estimated number of white croaker adult females (FH) whose 

reproductive output was equivalent to the adjusted number of larvae entrained per 

year (EAc9_T) at Diablo Canyon Power Plant including the standard error ofthe 

estimate (SE(FH)) and 90% confidence limits (C.L.). 

Analysis Period FH 

Upper Lower 

SE(FH) 90% C.L. 90% C.L. 

1) Oct 23, 1996-Sep 30, 1997 

2) Oct 1,1997-Sep 30, 1998 

3) Jul 1, 1997-Jun 30, 1998 

5,110 12,300 268,000 

7,380 17,800 387,000 

97 

141 

7,500 18,100 394,000 143 

Table 5.2.7-4. White croaker (Genyonemus lineatus): Sensitivity analysis for FH from 

the three analysis periods recalculated for each model input parameter (ff ): EAdj_T ± 

1.645 SE(ff); other parameters are Q.et\.MSCV0) where CV(0 ) = 1.0 or 100%. 

a) Analysis Period 1: Oct 1, 1996-Sept 30,1997 

Parameter 

FH 

^Adj-T 

S

 egg 

S larvae 

U Eggs/yr 

Longevity 

Maturation 

Estimate 

= 5,110 

305,000,000 

0.607 

0.187 

105,000 

12 

2 

Minimum 

4,800 

3,100 

987 

987 

2,320 

4,650 

Recalculated FH 

Maximum 

5,430 

26,500 

•26,500 

26,500 

162,000 

6,390 

Range 

626 

23,400 

25,500 

25,500 

159,000 

1,740 

TENERA E9-055.0 5-284 Final 316(b) Demonstration 

March 1,2000 
P.3 

5.2.7 White Croaker 

Table 5.2.7-4. White croaker (Genyonemus lineatus): Sensitivity analysis for FH from the three 

analysis periods recalculated for each model input parameter (ff): EAdj_T ± 1.645 SE(6); other 

parameters are 0.e±\M5Cr0) whereCV(ff)= 1.0 or 100% 

b) Analysis Period 2: Oct 1, 1997-Sept 30, 1998 

Parameter 

FH 

pAdj-T 

S

 egg 

S larvae 

# Eggs/yr 

Longevity 

Maturation 

Estimate 

= 7,380 

440,000,000 

0.607 

0.187 

105,000 

12 

2 

Minimum 

6,660 

4,480 

1,420 

1,420 

3,360 

6,710 

Recalculated FH 

Maximum 

8,110 

38,200 

38,200 

38,200 

233,000 

9,230 

Range 

1,450 

33,800 

36,800 

36,800 

230,000 

2,520 

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

1 

i 

t 

! 

I 

I 

Parameter 

FH 

E 

^•Adj-T 

S

 egg 

S larvae 

# Eggs/yr 

Longevity 

Maturation 

Estimate 

= 7,500 

447,000,000 

0.607 

0.187 

105,000 

12 

2 

Minimum 

6,780 

4,550 

1,450 

1,450 

3,410 

6,820 

Recalculated FH 

Maximum 

8,230 

38,900 

38,900 

38,900 

237,000 

9,380 

Range 

1,450 

34,300 

37,400 

37,400 

234,000 

2,560 

TENERA E9-055.0 5-285 Final 316(b) Demonstration 

March 1,2000 
P.4 

5.2.7 White Croaker 

Table 5.2.7-5. White croaker (Genyonemus lineatus): Monthly estimates of proportional 

entrainment (PE,) and annual proportion of larvae hatched in the ith 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 PP SE ffl f SP(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 

0.0244 

0 

0 

0 

0 

0 

0.0340 

0.000630 

0.000390 

0.00203 

0.00526 

0.00948 

0.0293 

0 

0 

0 

0 

0 

0.00858 

0.000450 

0.000120 

0.000720 

0.00146 

0.0116 

0.00704 

0.00447 

0.00584 

0.000570 

0.00135 

0.0628 

0.139 

0.00780 

0.0532 

0.293 

0.425 

0.000590 

0.000890 

0.000620 

0.000690 

0.000220 

0.000370 

0.00457 

0.00489 

0.000750 

0.00277 

0.00932 

0.0107 

0.000200 

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

Survey Start Date PE, SE m f SP(f) 

Jul 21, 1998 

Aug 26, 1998 

Sep 16, 1998 

Oct 6, 1998 

Nov 11, 1998 

Dec 9, 1998 

Jan 12, 1999 

Feb 3,1999 

Mar 17, 1999 

Apr 14, 1999 

May 24, 1999 

Jun 23, 1999 

ERA E9-055.0 

0 

0 

0 

0 

0 

0.00545 

0.00492 

0.0122 

0.0302 

0 

0 

0 

0 

0 

0 

0 

0 

0.00325 

0.000830 

0.00558 

0.0104 

0 

0 

0 

5-286 

0.00221 

0 

0 

0 

0 

0.0348 

0.673 

0.104 

0.186 

0 

0 

0 

0.000810 

0 

0 

0 

0 

0.00338 

0.00931 

0.00606 

0.00728 

0 

0 

0 

Final 316(b) Demonstration 

March 1,2000 

1 

I 
P.5 

5.2.7 White Croaker 

" 

. . 

tu 

w 

T— 

+ 

CO 

E 

CO 

c 

cu 

Q Mean 

0.38-

0.36-

0.34-

0.32-

0.30-

0.28-

0.26-

0.24-

0.22-

0.20-

0.18-

0.16-

0.14-

0.12-

0.10-

0.08-

0.06-

0.04-

0.02-

o.oo-

• designatessurve 

j 

Jlh III. It .1 

-

White croaker (Genyonemus lineatus) 

Sn" ir?ir"''"r"'"!"nmT r 

| 0 |N | D | J | F |M |A |M 

I

 1996

 1 

y with density* 0 

.(.Jit mmtriiti m? » * 

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

1997 | 1098 | 

Survey Date 

• ' , 1 t 

j|F|M|A|M|J | 

1S99 1 

Figure 5.2.7-1. Weekly mean larval density (#/m3 + 1 S.E.) at the DCPP intake. 

TENERA E9-055.0 5-287 Final 316(b) Demonstration 

March 1,2000 
rn 

z 

m 

n 

m 

CO 

o 

Ol 

yi 

b 

• 

00 

oo 

3 

QL 

co 

cn 

ii 

- ^-* 

to CU o sa 

o o 

o 3 

White croaker (Genyonemus lineatus) 

CO 

E 

4.0 

3.5 

3.0 

2.5 

2.0 

1.5 

1.0 

0.5 

0.0 

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 5.2.7-2a. Mean larval density (#/m1) collected in the DCPP study grid cells and at tiie entrainment sampling location. 

cn 

$ 

3" 

o 

3 

0) 

sr. 

TJ 

b> 
m 

z 

m 

m 

CO I 

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01 

O! 

y i 

1 ro 

00 

co 

3 

9L 

10 

-- tn 

mm 

to cu 

O ~*. 

o o 

O 3 

White croaker (Genyonemus lineatus) 

CO 

E 

4.0 

3.5 

3.0 

2.5 

2.0 

1.5 

1.0 

0.5 

0.0 

Depth Contours 

- 20 meters 

— — 40 meters 

•m^m 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 5.2.7-2b (continued). Mean larval density (tf/m1) collected in the DCPP study grid cells and at die entrainment sampling location. 

::;3 
m 

z 

m 

m 

(O 

i o 

Ol 

Ol 

to 

(O o 

3 

cu_ 

CO 

at 

&_ 

2 O 

If 

to cu 

O mf. 

o o 

O 3 

White croaker (Genyonemus lineatus) 

co 

4.0 

3.5 

3.0 

2.5 

2.0 

1.5 

1.0 

0.5 

0.0 

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 5.2.7-2c (continued). Mean larval density (#/m3) collected in the DCPP study grid cells and at the entrainment sampling location. 

to 

ZT 

o 

5 

CD ' 

"• 

bo 
m 

z 

m 

£ 

m co 

• o 

Ol 

Ol 

b 

01 

I 

ro 

co 

3 

9L 

w 

at 

2 ° 

M 

to S o =•. o o 

o 3 

White croaker (Genyonemus lineatus) 

CO 

E 

4.0 

3.5 

3.0 

2.5 

2.0 

1.5 

1.0 

0.5 

0.0 

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 5.2.7-2d (continued). Mean larval density (tf/m-1) collected in the DCPP study grid cells and at the entrainment sampling location. 

ro 

• ^ 1 

O 

1 

o 

01 

X" 

CD 

"• 

co 
P.10 

5.2.7 White Croaker 

CD 

o 

c 

a 

i_ 3 O O 

O o 

C s -

CU 

3 

cr 

a> 

c 

O 

a. 

ill 

White croaker (Genyonemus lineatus) 

N= 3,529 

1 m-m*T~~mmT~~^-T^mm.~T 

O.S 1.3 . 1. 8 2. 3 2 . a 3. 3 3. 8 4. 3 4. 8 S. 3 

f * 

Length Category (mm) 

o - r — 

1 2 

- I — 

1 5 -1 rrr 

2 1 

Estimated age (days) 

Figure 5.2.7-3. 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 5-292 Final 316(b) Demonstration 

March 1,2000 
5.2.7 White Croaker 

p.11 

White croaker (Genyonemus lineatus) 

1 5 -1 

l O -

Cl) 

u 

C

 5-1 

CD 

O 

1% 

Min 

Median 

Entrainment: N=150 

Mean 

99% 

VI ax 

>» 

« 15-| 

c 

CD 

3 —| Min 

cr 

CD 

"- io-" 

c 

CD 

O 

CD 5 — 

1% 

2.0 2.5 3.0 3.5 

Grid: N=1,263 

Median! Mean 

4.0 4.5 V****?? 

99% 

Max 

llilhhliilii. ll 

1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5

 r^"J 

Length Category (mm) 

Figure 5.2.7-4. 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 5-293 Final 316(b) Demonstration 

March 1,2000 
P.12 

5.2.7 White Croaker 

S.E.) 

E 

5S, Mea

n Density 

0.60 — 

0.55 ~= 

0.50"-= 

0.45-*: 

0.40-: 

0.35 — 

0.30-J 

0.25-^ 

0.20-^ 

O-15-i 

0.10 — 

0.05~| 

0.00 ~E 

-0.05 -= 

-0.10 — 

White croaker (Genyonemus lineatus) 

I 

I 

T 

i i 

i 

• 

m 

lllll l 

1990 1991 1992 1993 1994 1995 

Year 

\ 

i 

1996 

i 

I 

1997 

i 

I 

1998 

Figure 5.2.7-5. 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 of data (December through June) 

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

TENERA E9-055.0 5-294 Final 316(b) Demonstration 

March 1,2000 
P.13 

5.2.7 Whits Croaker 

White croaker (Genyonemus lineatus) - mean duration 

0.24 0 ~ 

0.210 -

O.10 2 -

o.-ie e 

0.14 4 

£ 0.12 0 

o.oee 

0.07 2 -

0.04 8 

0.02 4 — 

o.ooo 

Analysis Period 3: Jul 1997-Jun 1998 

R s alona'hor a 

Estimate 

90% C.l. 

Densit y 

Extrapolate d R a 

Pu= 0.00255 ±0.0266 

III I 

Ox Sx lOx 1Bx 20x 2Sx SOx SSx 40x 

O km S7 km 174 Km 201 Km 347 km 434 km S21 km 608 km BBS kn 

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

Equivalen t Dlatane e Alongthor a 

White croaker (Genyonemus lineatus) - mean duration 

Analysis Penod 4: Jul 1998-Jun 1999 

Estimate 

90% C.l. 

Ox 

O k m 

Sx 

8 7 k m 

1 0 x 1 Sx 20 x 

1 7 4 k m 28 1 k m 34 7 kn 

2 Sx SOx SSX 40 x 

4 3 4 k m S2 1 k m 80 8 k m 69 6 k m 

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

Equivalen t Distanc e Alongihor * 

Figure 5.2.7-6a. Total annual entrainment mortality (P^) and 90% confidence interval (CI.) as 

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

(p"s) used to approximate die alongshore extent of die study grid population expanded on die 

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

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

indicated. 

TENERA E9-055.0 5-295 Final 316(b) Demonstration 

March 1.2000 
P.14 

5.2.7 White Croaker 

White croaker (Genyonemus lineatus) - maximum duration 

R a alongshor e 

Analysis Period 3: Jul 1997-Jun 1998 

Density Extrapolated Ps off scale 

1/Ps=128 

PM = 0.00133 ±0.0265 

Estimate 

90% C.l. 

Ox 

O k m 

Sx 

8 7 k m 

—i—|—i—i—i—l—|—l—l—.—i—|— r 

l O x IS x 20 x 2S x 

1 7 4 k m 28 1 k m 34 7 k m 43 4 kr 

SOx SSx 40 x 

6 2 1 k m 80 8 k m 80 S k m 

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

Equivalen t Distanc e Alongshor e 

White croaker (Genyonemus lineatus) - maximum duration 

O.OO* 

Analysis Period 4: Jul 1998-Jun 1999 

Estimate 

90% C.l. 

Densit y 

Extrapolate d R a 

Ox Sx 10 x IS x 20 x 26 x 30 x SSx 40 x 

O k m 8 7 k m 17 4 k m 28 1 k m 34 7 k m 43 4 k m S2 1 k m 80 8 k m 80 S k m 

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

Equivalen t Diatano e Alongshor e 

Figure 5.2.7-6b. Total annual entrainment mortality (P^) and 90% confidence interval (CI.) as 

a function of die reciprocal of die fraction of die population at risk and contained in die study grid 

( R) used to approximate die alongshore extent ofthe study grid population expanded on the 

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

extended alongshore using bodi onshore and alongshore current movements widi 90% CI.'s 

indicated. 

TENERA E9-055.0 5-296 Final 316(b) Demonstration 

March 1.2000 
P.15 

- ^ 

5.2.7 White Croaker 

Commercial White Croaker (Genyonemus lineatus) Landings from 

the Morro Bay Area 

100 

-• 80 

^•60 -

I 40-

20 

0 n W 1 _ -

•Morro Bay (MT) 

DPort San Luis (MT) 

nA IL JJ 

in 

rO) 

ro> 

O 

ro> CO 

o> 

o 

00 

cn 

m r- O) «-

co co co cn 

cn cn cn o> 

CO 

Ot 

Or 

W 

cn 

ot 

cn 

Year 

Figure 5.2.7-7. Annual commercial landings (MT) of white croaker (Genyonemus lineatus) at 

ports in the Morro Bay area (source: California Department of Fish and Game Database). 

TENERA E9-055.0 5-297 Final 316(b) Demonstration 

March 1.2000 
P.16 

I 

Blank Page 
5.2.8 Monkeyface Prickleback 

5.2.8 Assessment of Monkeyface Prickleback (Cebidichthys 

violaceus) 

Cebidichthys violaceus (Girard 1854); monkeyface prickleback; length to 76 cm; 

southern Oregon to Bahia San Quintin, north-central Baja California; 

intertidal to 24 m; uniform black, olive, or gray, except for black streaks at 

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

The monkeyface prickleback (Cebidichthys violaceus) is a member ofthe family Stichaeidae, 

i 

which is primarily distributed in the northern Pacific Ocean (Nelson 1994). The family consists 

of three subfamilies, 31 genera, and about 60 species (Nelson 1994). The monkeyface 

prickleback belongs to the subfamily Xiphisterinae, which contains 15 species, several of which 

are common to the California coast (Miller and Lea 1972; Nelson 1984). The monkeyface 

prickleback is found as far south as central Baja California, Mexico but is rare south of Point 

Conception (Burge and Schultz 1973; Love 1996). They are common in crevices and rocks from 

the upper intertidal to shallow rocky reefs at depths of about 24 m and appear to be highly 

territorial (Wang 1986; Love 1996). They are not commonly sighted subtidally because of their 

cryptic nature (Burge and Schultz 1973). In central California, juveniles are most abundant in 

water about 0.5 m above mean lower low water (MLLW) tidal height and commonly found under 

rocks at low tide (Love 1996). Investigations into the diet of this fish in Diablo Cove reveal it is 

an herbivore feeding largely on red algae (Burge and Schultz 1973). 

Monkeyface prickleback lay demersal, adhesive eggs (Wang 1986; Fitch and Lavenberg 1971; 

Baxter 1974) and exhibit parental egg-guarding behavior (Fitch and Lavenberg 1971; Bane and 

Bane 1971). Spawning has been reported from January to May (Fitch and Lavenberg 1971; 

Baxter 1974; Wang 1986; Love 1996). In Diablo Cove, females were full of eggs in January, 

contained small undeveloped eggs in July, and had spent ovaries in September (Burge and 

Schultz 1973). This evidence, coupled with the presence of young-of-the-year (YOY) in fall, 

suggests late summer spawning (Burge and Schultz 1973). Additionally, maturing ovaries were 

TENERA E9-055.0 5-298 Final 316(b) Demonstration 

March 1,2000 
P.18 

5.2.8 Monkeyface Prickleback 

observed from December through June, mature ovaries from March through May, and spent 

ovaries from February through August with one in December. Older fish appear to spawn earlier 

in the season than younger fish (Marshall and Wyllie Echeverria 1991). 

** 

Fecundity increases with age and length. Smaller fish produce 6,000 to 8,000 eggs (Fitch and 

Lavenberg 1971; Baxter 1974) while larger females produce more. A 41 cm SL female aged 7 yr 

produced 17,500 eggs, and a 61 cm SL female aged 11 yr had 46,000 eggs (Marshall and Wyllie 

Echeverria 1991). 

Monkeyface prickleback larvae are planktonic (Wang 1986), but little else is known about the 

early life history of this species. A family member, the black prickleback (Xiphister 

atropurpureus), was shown to have marked positive phototaxis (attraction to light) for 3-5 d, 

after which time they become negatively phototactic (Peppar 1965 in Coleman 1992). There were 

no data on monkeyface prickleback larval growth rates in the literature. The larval growth rate 

(Stepien 1986) for an ecologically similar species, the giant kelpfish (Heterostichus rostratus, 

family Clinidae), was substituted for the missing C. violaceus growth rate. The accuracy of this 

growth rate as it applies to monkeyface prickleback is unknown, but it represents the best 

available data from the current scientific literature. 

Longevity ofthe monkeyface prickleback was estimated at 18 yr from a 67 cm SL fish (Marshall 

and Wyllie Echeverria 1991). Females 20 cm in length from Monterey Bay, California were aged 

at 12 to 15 yr (Fitch and Lavenberg 1971). The oldest age estimated from fish collected in Diablo 

Cove was 14 yr based on two individuals that were approximately 49 cm SL and 64 cm SL 

(Burge and Schultz 1973). Considering this species reaches 76 cm SL (Eschmeyer et al. 1983), it 

probably lives longer. Fitch and Lavenberg (1971) reported the age at 50% maturity at 3-4 yr. 

However, Marshall and Wyllie Echeverria (1991) determined that age at first maturity is 4 yr, age 

at 50% maturity is 5 yr, and age at 100% maturity is 7 yr. 

The fishery for monkeyface prickleback is largely recreational although some are sold 

commercially (Wang 1986; Love 1996). They are usually caught using a fishing method called 

TENERA E9-055.0 5-299 Final 316(b) Demonstration 

March 1.2000 
P.19 

1 

1 

I 

1 

1 

1 

1 

1 

I 

I 

I 

5.2.8 Rflorakeylface Prickleback 

"poke-poling" among intertidal rocks. A small commercial fishery has been underway in the 

Morro Bay area since 1993 (California Department of Fish and Game Database). 

S.2.8.H Summmroairy ©f Fo@!dl C@il©©ttDomis 

Abundances of monkeyface prickleback larvae at the DCPP intake structure were seasonal during 

the years 1996-1999 (Appemiiix M), with highest densities occurring during the spring and 

summer (Figonre 5.2.8-1). Few larvae of this species were collected during die months of August 

through December. It appears diat the initiation of reproduction in monkeyface prickleback might 

have been delayed by a month or two during 1998. This might have been due to the EI Nino 

)j event diat began in 1997 (Lynn et al. 1998; NOAA 1999). There were 7,090 larval monkeyface 

prickleback identified from 1,253 bongo net subsamples collected at die DCPP intake structure 

between October 1996 and June 1999 representing 27% of die intake subsamples collected and 

processed during that period. 

Monkeyface prickleback larvae were generally present in die DCPP study grid during January 

through July of each year (Apperadlk M), with their highest abundance occurring during May 

1998 and April-May 1999 (Figuiire 5.2.8^2). They were distributed in higher density in the cells 

closest to shore in the southern half of the grid. There were 904 larval monkeyface prickleback 

identified from 294 bongo net subsamples representing 10% ofthe study grid subsamples 

collected and processed from July 1997-June 1999. 

Standard lengths of all monkeyface prickleback larvae collected at the DCPP intake structure 

between October 1996 and June 1999 ranged from a minimum of 2.8 mm to a maximum of 24.6 

mm; corresponding age estimates ranged from zero days (just hatched) to about 88 d (Figure 

5.2.8-3). The growth rate of larval giant kelpfish (0.25 mm/d) reported by Stepien (1986) was used 

to estimate ages of these monkeyface prickleback larvae. The central 98% of this length-frequency 

distribution resulted in minimum and maximum lengths for the analyses of 5.7 mm and 12 mm, 

respectively. The mean larval length in this distribution was 7.33 mm, which corresponded to an 

estimated age of 6.5 d. We assumed that larvae shorter than the minimum length ofthe central 

98% ofthe distribution had just hatched and were aged zero days. Subsequent ages were estimated 

TENERA E9-055.0 5-300 Final 316(b) Demonstration 

March 1,2000 
P.20 

5.2.8 Monkeyface Prickleback 

from this assumed hatch length. No reported hatching length for monkeyface prickleback was 

found in the scientific literature. Reported hatching size for bluebarred prickleback 

(Plectobranchus evides) is <7.4 mm (Moser 1996). Individuals that appeared to be different ages 

*•% 

based on length might be the same age as a result of natural variation in hatching size or variable 

shrinkage after preservation. Thus, it is possible that at least some ofthe smaller-sized larvae, at 

least up to 5.7 mm and possibly larger, had just hatched before being caught. 

Distributions of monkeyface prickleback larval lengths at the DCPP intake structure and in the 

study grid were compared using a Kolmogorov-Smirnov test (Figure 5.2.8-4). The test did not 

detect a significant difference between die two distributions (p > 0.288). A t-test also did not 

detect a significant difference (p > 0.75) between the mean lengths from the two locations. On 

average, these larvae were estimated to be about 6.5 d old, indicating that die power plant 

entrains relatively young monkeyface prickleback larvae. In addition, these data indicate diat die 

age and size structure of die population entrained is nearly identical to diat of die population at 

risk. 

5.2.8.2 Estimating Total Annual Entrainment 

The annual estimates ofthe average entrainment for 1996-97 Analysis Period 1 (ET = 

106,000,000) and 1997-98 Analysis Period 2( ^ = 119,000,000) were similar (Table 5.2.8-1). 

The small differences in the estimated entrainment numbers are not statistically significant 

because 95% confidence intervals approximated by ±2 • SE(ET) would not overlap. 

Annual entrainment estimates of monkeyface prickleback larvae, adjusted to the long-term 

average from nine years of Intake Cove plankton sampling (Figure 5.2.8-5), ranged from 

61,500,000 (SE =5,580,000) in Analysis Period 2 to 83,100,000 (SE =8,160,000) in Analysis 

Period 1 (Table 5.2.8-2). The adjustment index (/ //,) was calculated as the ratio between the 

nine year average (/ ) of Intake Cove sampling and the average annual index estimated from 

these same tows during the year being adjusted (/,). The average index for the years 1997 and 

1998 (/;) were 0.019 and 0.029 larvae/m3, respectively, while the long-term average index (7) 

was 0.0148 larvae/m3 for the years 1990-1998, yielding the ratios 111, of 0.783 for 1997 and 

TENERA E9-055.0 5-301 Final 316(b) Demonstration 

March 1.2000 
P.21 

5.2.8 Monkeyface Prickleback 

0.517 for 1998. The differences between the adjusted estimates were not statistically significant 

because 95% confidence intervals approximated by ±2 • SE(EAdj_T) did not overlap. 

NOTE: Entrainment estimates for monkeyface prickleback larvae were not used to calculate 

annual adult losses (FH or AEL) because there were insufficient demographic data with which to 

parameterize these approaches. 

5.2.8.3 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±0.464 (±\SE(PE,)) in January 

1999 (Table 5.2.8-3). Periods when both PE, and the annual proportion of larvae hatched in the 

hh survey period (f) were equal to zero indicated that no larvae were collected at either the 

DCPP intake or from the study grid. When PE, = 0 but fj>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/ occurred between April and June in both analysis 

periods indicating that these were periods of high monkeyface prickleback larval abundance at 

the intake structure. These surveys were also associated with the largest values of PE, except for 

the estimate in January 1999. Since f was used to weight individual estimates of PE,, those 

with higher f values were proportionally more important to the annual entrainment mortality 

estimates. 

Larval monkeyface prickleback were distributed close to shore in the study grid subsamples 

(Figure 5.2.8.2) and similar to observed adult distributions in shallow nearshore areas up to 

depths of 25 m (Miller and Lea 1972). Therefore, Ps was only calculated using alongshore 

current movement and not offshore extrapolation of study grid abundance. ETM results for 

monkeyface prickleback show the differences in how estimated larval durations can affect 

calculation of Pu (Figures 5.2.8-6a and b). As expected, values for PM increase with increasing 

values of Ps (i.e., decreasing \IPS ) for shorter larval duration between periods. The probability 

of entrainment is less for the shorter duration because ofthe reduced time period for larval 

transport to occur. The difference between years for PM is much less for the shorter larval 

TENERA E9-055.0 5-302 Final 316(b) Demonstration 

March 1,2000 
P.22 

5.2.8 Monkeyface Prickleback 

duration than the longer duration (0.11 to 0.16 vs. 0.11 to 0.23). The larger confidence intervals 

around Ps for the longer larval duration reflect the larger uncertainty that results from increased 

alongshore transport. The point estimates for PM for both larval durations are greater during 

1997-1998 because of weaker alongshore currents associated with El Nino conditions. 

5.2.8.4 Interpretation of Assessment Results 

A limited fishery exists for monkeyface prickleback. Monkeyface prickleback landings were first 

recorded in 1993 at Port San Luis and Morro Bay, peaked in 1995, and declined through 1998 

(Figure 5.2.8-7). Landings ranged from a low of 3 kg at Port San Luis in 1993 to a high of 180 

kg at Morro Bay in 1995. The average combined annual catch between 1993 and 1998 from the 

Morro Bay area was 75 kg/yr. Because ofthe limited fishery for this species, there have been no 

estimates of stock size or adult density. Therefore, the catch data will not be used to compare 

harvest mortality rates to PM . 

The highest annual densities of monkeyface prickleback larvae from Intake Cove surface 

plankton tows occurred in 1990. Abundances in 1997 and 1998 were slightly above the long-term 

mean density (Figure 5.2.8-5). Adult monkeyface prickleback abundance was low and variable 

on the transects surveyed during the DCPP Receiving Water Monitoring Program fish 

observations from 1978 to 1998 (Figure 5.2.8-7). Monkeyface prickleback have a relatively long 

lifespan that has been estimated at up to 18 yr from a 67 cm SL fish (Marshall and Wyllie 

Echeverria 1991). Results ofthe ETM show that the power plant may annually entrain 11-23% of 

the monkeyface prickleback larvae from an area 7 to 8 times the area ofthe study grid (Figure 

5.2.8-6). The wide range in the size of larvae entrained (<3 mm to >24 mm) indicate that 

monkeyface prickleback larvae are vulnerable to entrainment over a large portion of their larval 

life (Figure 5.2.8-3). This could indicate an increased potential for impacts from entrainment on 

this taxon. In the absence of other estimates of adult population abundance, there is no definitive 

way to determine whether this level of larval mortality is sufficient to cause a long-term local 

population decline. However, this species is widely distributed from southern Oregon to Baja, 

TENERA E9-055.0 5-303 Final 316(b) Demonstration 

March 1,2000 
P.23 

5.2.8 Monkeyface Prickleback 

and it is unlikely that larval losses from entrainment that may affect local adult abundances would 

affect the larger population. 

TENERA E9-055.0 5-304 Final 316(b) Demonstration 

March 1.2000 
P.24 

5.2.8 Monkeyface Prickleback 

Table 5.2.8-1. Estimated total annual entrainment (ET ) and standard error 

(SE(Ej)) for monkeyface prickleback (Cebidichthys violaceus) larvae from 

the three analysis periods. 

Analysis Period ET SE(ET) 

1) Oct 23, 1996-Sept 30, 1997 106,000,000 10,400,000 

2) Oct 1, 1997-Sep 30, 1998 119,000,000 10,800,000 

3) Jul 1,1997-Jun 30, 1998 116,000,000 10,700,000 

Table 5.2.8-2. Estimated total annual adjusted entrainment (EAdj_-) and 

standard error (SE(EAdJ_T)) for monkeyface prickleback (Cebidichthys 

violaceus) larvae from the three analysis periods. 

Analysis Period 

1) Oct 23, 1996-Sep 30, 1997 

2) Oct 1, 1997-Sep 30, 1998 

3) Jul 1,1997-Jun 30,1998 

PAdj-T 

83,100,000 

61,500,000 

60,200,000 

SP{pAdj-T) 

8,160,000 

5,580,000 

5,520,000 

TENERA E9-055.0 5-305 Final 316(b) Demonstration 

March 1.2000 
P.25 

5.2.8 Monkeyface Prickleback 

Table 5.2.8-3. Monkeyface prickleback (Cebidichthys violaceus): Monthly estimates of 

proportional entrainment (PE,) and annual proportion of larvae hatched in the /th 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 PP SE(PE,) f 

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

Survey Start Date PE, SE^PE,) f, 

SP(f) 

Jul 21, 

Aug 25, 

Sep 29, 

Oct 20, 

Nov 17, 

Dec 10, 

Jan 22, 

Feb 26, 

Mar 18, 

Apr 15, 

May 18, 

Jun 8, 

1997 

1997 

1997 

1997 

1997 

1997 

1998 

1998 

1998 

1998 

1998 

1998 

0.0247 

0 

0 

0 

0 

0 

0 

0.00621 

0.0217 

0.139 

0.0135 

0.0542 

0.00723 

0 

0 

0 

0 

0 

0 

0.00369 

0.0108 

0.0481 

0.00301 

0.0123 

0.0437 

0 

0 

0 

0 

0 

0.00320 

0.0122 

0.0379 

0.403 

0.188 

0.313 

0.00248 

0 

0 

0 

0 

0 

0.000510 

0.00101 

0.00490 

0.0164 

0.00981 

0.0126 

SE(f) 

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 

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0 

0 

0 

0 

0 

0.859 

0.0384 

0.0223 

0.0401 

0.0155 

0.0615 

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0.00972 

0 

0 

0 

0 

0 

0.464 

0.0245 

0.00636 

0.0146 

0.00440 

0.0170 

5-306 

0.0580 

0 

0 

0 

0 

0 

0.0116 

0.0389 

0.119 

0.434 

0.178 

0.161 

0.00483 

0 

0 

0 

0 

0 

0.00114 

0.00348 

0.00538 

' 0.0140 

0.00729 

0.00667 

Final 316(b) Demonstration 

March 1,2000 
P.26 

5.2.8 Monkeyface Prickleback 

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TENERA E9-055.0 5-307 Final 316(b) Demonstration 

March 1,2000 
P.27 

5.2.8 Monkeyface Prickleback 

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TENERA E9-055.0 5-308 Final 316(b) Demonstration 

March 1,2000 
P.28 

5.2.8 Monkeyface Prickleback 

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TENERA E9-055.0 5-309 Final 316(b) Demonstration 

March 1,2000 
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TENERA E9-055.0 5-311 Final 316(b) Demonstration 

March 1.2000 
5.2.8 Monkeyface Prickleback 

P.31 

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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 5-312 Final 316(b) Demonstration 

March 1,2000 
P.32 

5.2.8 Monkeyface Prickleback 

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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 5-313 Final 316(b) Demonstration 

March 1,2000 
r -

P.33 

5.2.8 Monkeyface Prickleback 

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Figure 5.2.8-5. 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 of data (December through June) 

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

TENERA E9-055.0 5-314 Final 316(b) Demonstration 

March 1,2000 
P.34 

5.2.8 Monkeyface Prickleback 

Monkeyface prickleback (Cebidichthys violaceus) - mean duration 

O.OO* 

Analysis Period 3: Jul 1997-Jun 1998 

Pa alongahore 

90% C.l. 

Ox Sx 10x ISx 20x 26x SOx SSx 40x 

O km 87 Km 174 km 261k m 347 km 43 4 km 621 km 60S km SBS km 

Siz e of Population 'Relative to Study Oli d 

Equivalent Diatanoe Alongshor e 

Monkeyface prickleback (Cebidichthys violaceus) - mean duration 

Analysis Period 4: Jul 1998-Jun 1999 

Estimate 

90% C.l. 

Siz e of Population Relative to Study Oli d 

Equivalent Diatanoe Alongahor e 

Figure 5.2.8-6a. Total annual entrainment mortality (P^) and 90% confidence interval (CI.) as a 

function ofthe reciprocal of die fraction of die population at risk and contained in die study grid 

(Ps) used to approximate die alongshore extent ofthe study grid population expanded on the 

basis of alongshore current movements widi the 90% C.I. indicated. 

TENERA E9-055.0 5-315 Final 316(b) Demonstration 

March 1,2000 
P.35 

5.2.8 Monkeyface Prickleback 

Monkeyface prickleback (Cebidichthys violaceus) - maximum duration 

Analysis Period 3: Jul 1997-Jun 1998 

Estimate 

90% C.l. 

Siz e of Population Relative to Study Oli d 

Equivalent Diatanoe Alongahor e 

Monkeyface prickleback (Cebidichthys violaceus) - maximum duration 

Analysis Period 4: Jul 1998-Jun 1999 

Estimate 

90% C.l. 

Ox 

O km 

Sx 

ST km 

i—i—i—;—i — 

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20x 2Sx 

347 km 43 4 km 

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SOx SSx 

621 km SOS km 

40x 

80S km 

Siz e of Population Relative to Study Oli d 

Equivalent Diatanoe Alongahore 

Figure 5.2.8-6b. Total annual entrainment mortality (/-^) and 90% confidence interval (CI.) as 

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

( P ) used to approximate the alongshore extent ofthe study gnd population expanded on die 

basis of alongshore current movements with die 90% CI. indicated. 

TENERA E9-055.0 M 16 Final 316(b) Demonstration 

March 1. 2000 
P.36 

a) 

5.2.8 Monkeyface prickleback 

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

observed per 50-meter subtidal benthic transect in the DCPP RWMP South Control area. 

Spline smoothing algorithm used to draw the curve through the points. 

TENERA E9-055.0 5-317 Final 316(b) Demonstration 

March 1,2000 
P.37 

5.2.9 Kelpfishes 

5.2.9 Assessment of Clinid Kelpfishes (Clinidae) 

Gibbonsia elegans (Cooper 1864); spotted kelpfish; length to 16 cm; Piedras 

Blancas Pt., central California to Bahia Magdalena, southern Baja California, 

including Isla Guadalupe; to 56 m (Miller and Lea 1972; Eschmeyer et al. 

1983); green to brown or tan or reddish, often blotched or streaked 

(Eschmeyer et al. 1983). 

Gibbonsia metzi Hubbs 1927; striped kelpfish; length to 24 cm; Vancouver Is., 

British Columbia to Punta Rompiente, central Baja California; intertidal to 

9.1 m (Miller and Lea 1972; Eschmeyer et al. 1983); reddish to light brown 

with stripes or darker mottling (Eschmeyer et al. 1983). 

Gibbonsia montereyensis Hubbs 1927; crevice kelpfish; length to 15 cm; British 

Columbia to Rio Santo Tomas, northern Baja California. 15-37 m. (Miller 

and Lea 1972; Eschmeyer et al. 1983); reddish to brown or lavender, plain 

colored to spotted or striped (Eschmeyer et al. 1983). G. erythra is a 

synonym (Stepien and Rosenblatt 1991). 

I 

I 

Heterostichus rostratus Girard 1854; giant kelpfish; length to 61 cm; British 

Columbia to Cabo San Lucas, southern Baja California, including Isla 

Guadalupe; intertidal to 40 m (Miller and Lea 1972; Eschmeyer et al. 1983); 

giant kelpfish come in as many as three color forms (red, brown, or green) 

usually associated with the plant habitats from which they were collected 

(Stepien 1987). 

In the family Clinidae there are three species of kelpfishes in the genus Gibbonsia and the giant 

kelpfish (Heterostichus rostratus) that occur along the west coast of North America from Baja to 

British Columbia (George and Springer 1980). Nelson (1994) indicates that worldwide there are 

three groups of clinids with about 20 genera and 73 species. Clinids are small (generally <25 cm 

SL; exception H rostratus ca. 60 cm SL), primarily demersal residents of nearshore rocky reefs 

and kelp and seaweed beds in temperate marine waters (Lamb and Edgell 1986; Moser 1996). 

TENERA E9-055.0 5-318 Final 316(b) Demonstration 

March 1,2000 
P.38 

5.2.9 Kelpfishes 

There are no catch statistics for these species because they are not commercially or recreationally 

harvested. 

All four representatives of this family in central Califomia are oviparous (Nelson 1994), probably 

spawning demersal adhesive eggs (Fitch and Lavenberg 1971; Moser 1996) although Bane and 

Bane (1971) report striped kelpfish (Gibbonsia metzi) as having pelagic eggs. Larval forms are 

pelagic and are only identifiable to genus in the case of Gibbonsia spp. although giant kelpfish 

can be identified to species at most life stages. Yolk-sac duration in this latter species appears to 

be 2-3 d (Shiogaki and Dotsu 1972). Bane and Bane (1971) report a fecundity of around 2,300 

eggs/female for a spotted kelpfish (G. elegans). Kelpfishes of Gibbonsia spp. first spawn at 2 yr, 

may spawn more than once per year, and live to around 7 yr (Fitch and Lavenberg 1975). 

There is very little demographic information relating to the early life stages of clinids in general 

or specifically to the four representatives ofthe family found in central California. Growth of 

larval giant kelpfish was estimated by linear regression from data on lab-reared specimens 

(Stepien 1986) as 0.25 mm/d ±0.013 (slope ± 1 SE). A similar estimate of growth rate is not 

available for Gibbonsia spp., but ifthe growth rate for giant kelpfish is substituted for Gibbonsia, 

it allows us to estimate larval ages at entrainment and calculate ETM for kelpfishes. There are no 

available data to indicate how well the larval growth rate of giant kelpfish describes the larval 

growth of Gibbonsia spp. Therefore, using giant kelpfish larval growth is considered only as an 

approximation to the growth of Gibbonsia spp. larvae. Additionally, there are no literature 

estimates of early life stage survivorship for any ofthe clinids treated here, so FH and AEL are 

not calculated for the clinid kelpfishes. The relatively few identified larval giant kelpfish (42 at 

the DCPP intake and one from the study grid) were incorporated into the clinid kelpfish group for 

the analyses. 

5.2.9.1 Summary of Field Collections 

Estimates of kelpfish larval abundance at the DCPP intake structure during the years 1996-99 

indicate that species in this genus are continuous spawners (Appendix H) exhibiting at least two 

peaks in larval abundance per year. During the 1996-97 season, larval abundance at the intake 

TENERA E9-055.0 5-319 Final 316(b) Demonstration 

March 1,2000 
P.39 

1 

1 

1 

1 

i 

I 

I 

i 

5.2.9 (Kelpfishes 

M structure peaked in January and again in June-August (Figure 5.2.9-1). In the 1997-98 season, 

the January peak seen in the previous year did not occur, and the later peak appeared displaced 

w by about one month and occurred in May-June. Although there are fewer processed subsamples 

from the 1998-99 spawning season, the peaks appear to conform with the pattern for the 1996-

(jj 97 period. There were 9,361 larval kelpfishes identified from 2,808 bongo net subsamples 

y. collected at die DCPP intake structure between October 1996 and June 1999 representing 60% of I 

IE! the subsamples collected and processed from the intake structure during that period. 

Jj] Larval kelpfishes were relatively scarce in die DCPP study grid (Apperadax H), but the temporal 

distribution of abundance roughly corresponded to that observed at the DCPP intake structure. 

SI There were 467 kelpfish larvae identified from 213 bongo net subsamples in study grid between 

July 1997-June 1999 representing 7% ofthe study grid subsamples collected and processed. 

Kelpfish larval abundance was generally distributed widiin the 20 m isobath, and larvae were 

likely concentrated in unsampled areas inshore ofthe study grid (Marliave 1986). The apparently 

higher density of this species in the southern portion ofthe study grid results from the 

relationship postulated with depth above and the fact that more ofthe area in the southern half of 

the grid is within the 0-20 m depth range. 

Standard lengths ofthe Gibbonsia spp. larvae (7,331 larvae) measured from subsamples at die 

DCPP intake structure between October 1996 and June 1999 ranged from a minimum of 2.4 mm 

to a maximum of 23 mm (Fignare S.2.9-3). The minimum and maximum lengths, 4.1 mm and 12 

mm, from the central 98% of this length-frequency distribution were used in calculating larval 

duration. A larval growth rate from giant kelpfish of 0.25 mm/d (Stepien 1986) was applied to the 

range of lengths to estimate the ages ofthe entrained larvae. The mean larval length in this 

distribution was 6.4 mm at approximately 9 d of age. We assumed that larvae shorter than the 

minimum length ofthe central 98% ofthe distribution were just hatched and aged zero days. 

Subsequent ages were estimated from this length and up. Other reported data for this species 

suggests that hatching length is approximately 4.5 mm (Moser 1996), indicating that the smallest 

larvae observed represent either natural variation in hatch lengths within the population or the 

phenomenon of shrinkage following preservation (Theilacker 1980). The possibility remains diat 

TENERA E9-055.0 5-320 Final 316(b) Demonstration 

March 1,2000 
P.40 

5.2.9 Kelpfishes 

all larvae from the observed minimum length of 2.4 mm to the greatest reported hatching length 

of 4.5 mm (Moser 1996) could have just hatched, leading to overestimation of ages for all larvae 

<4.5 mm. 

Distributions of Gibbonsia spp. larval lengths at the DCPP intake structure and in the study grid 

(Figure 5.2.9-4) were compared using a Kolmogorov-Smirnov test. The test detected a 

significant difference between the two distributions (p <, 0.001). The length-frequency 

distributions in both sampiing locations were unimodal, with a few larger individuals. A t-test did 

not detect a significant difference (p > 0.786) between mean lengths at the DCPP intake and in 

the study grid. The estimated age for an average length larva was about 9 d. These data indicate 

diat entrained larvae were very young and that differences between age and length ofthe 

population entrained and the population at risk are very small. 

5.2.9.2 Estimating Total Annual Entrainment 

There was considerable variation of annual estimated mean entrainment of larval kelpfishes 

among years (Table 5.2.9-1). Approximately 186,000,000 (SE =4,740,000) kelpfish larvae were 

entrained in Analysis Period 1 while entrainment estimates ranged from 83,600,000 

(SE =4,150,000) to 124,000,00 (SE =5,000,000) between the two analysis periods in the 1997-

98 sampling season. All periods appeared to be different from one anodier because 95% 

confidence intervals approximated by 2 • SE(ET) did not overlap. 

Annual estimates ofthe number of kelpfish larvae entrained, adjusted to the nine year average 

estimated from Intake Cove surface plankton tow sampling (Figure 5.2.9-5), were 181,000,000 

( SE =4,610,000) for Analysis Period 1 and 308,000,000 (SE = 15,300,000) for Analysis Period 2 

(Table 5.2.9-2). The adjustment index (III,) was calculated as the ratio between the average 

( 7) of Intake Cove and the average annual index estimated from these same tows during the year 

being adjusted (/,). The average index for 1997 and 1998 (/,) was 0.0682 and 0.0181 larvae/m3, 

respectively, while the long-term average index (7 ) is 0.0664 larvae/m3 for the years 1990-

1998, yielding a ratio Til, of 0.974 for 1997 and 3.68 for 1998. The adjusted estimate for the 

1997-1998 period is larger than the unadjusted entrainment estimate, and was significantly 

TENERA E9-055.0 5-321 Final 316(b) Demonstration 

March 1,2000 
P.41 

5.2.9 Kelpfishes 

greater than the 1996-1997 adjusted estimate because 95% confidence intervals approximated by 

2 • SE(EAdj-T) did not overlap. 

NOTE: FH and AEL estimates were not calculated from the estimates of entrainment for 

kelpfishes because there were no demographic data available to parameterize these models. 

5.2.9.3 Empirical Transport Model (ETM) 

Monthly estimates of proportional entrainment (PE,) for kelpfishes from the surveys during the 

two years sampled ranged from a minimum of 0.00144±0.00156 (±\SE(PE,)) in March 1998 to 

a maximum of 0.346±0.189 in May 1998 (Table 5.2.9-3). There were other months when the / 

was larger than the value for May 1998, which would cause the PE, during that month to 

contribute more to the total PM value calculated for the ETM. There were no periods when PE, 

and fj were both equal to zero indicating that larvae were always present during the pasired 

entrainment and 72-hour study grid surveys. 

Kelpfish larvae from the study grid subsamples were primarily distributed in nearshore areas 

(Figure 5.2.9-2) and similar to reported adult distributions (Miller and Lea 1972). Therefore, Ps 

was calculated using only alongshore current movement and not by extrapolating study grid 

abundance offshore. The large differences in estimated ages of larval kelpfish at entrainment 

(9 vs. 31 d) can affect calculation of PM (Figure 5.2.9-6). As expected, values for PM were less 

for shorter larval durations because ofthe reduced period of larval transport. Estimates of PM for 

either larval duration are relatively similar within an analysis period for a given duration 

5.2.9.4 Interpretation of Assessment Results 

Kelpfish do not have any commercial or recreational fishery value, and there is little information 

on their ecological role in the community. Because ofthe limited fishery harvest data for these 

species (ca. 0.14 MT at Port San Luis in 1990), entrainment mortality rates (PM ) could not be 

compared to harvests. Additionally, there are no estimates of population size or adult density that 

could be used to convert PM into an estimate of adult equivalent loss. Annual mean density of 

TENERA E9-055.0 5-322 Final 316(b) Demonstration 

March 1.2000 
P.42 

5.2.9 Kelpfishes 

kelpfish larvae from Intake Cove surface plankton tows shows considerable variation in 

abundance relative to the long-term mean for the period 1995-1998 (Figure 5.2.9-5). Abundance 

ofthe local adult kelpfish population appears to decline from 1993-1998 (Figure 5.2.9-7). 

Results ofthe ETMshow that the power plant may annually entrain approximately 40% ofthe 

kelpfish larvae over an area six to seven times the area ofthe study grid (Figure 5.2.9-6). The 

length frequency distribution of entrained larvae shows a wide range of lengths, indicating that 

the larvae are subject to entrainment for a longer duration than other nearshore taxa. (Figure 

5.2.9-3). If Moser's (1996) estimate of size at flexion for spotted kelpfish Gibbonsia elegans is 

used for comparison, then the length frequency data indicates that post-flexion larvae are also 

being entrained. Although PM for kelpfishes is likely to be overestimated because of grid 

sampling that is biased for nearshore taxa, the relatively high probability of entrainment by the 

power plant intake as well as additional evidence of declines in local adult and larval abundance 

indicate a high likelihood for local impacts on this taxon. Additionally, local habitat for 

kelpfishes (the rocky habitat between Point Buchon and Point San Luis) is bordered to the north 

and south by large expanses of sandy beach that do not favor adult kelpfishes and may imply a 

geographically constrained subpopulation. However, the extent of larval duration estimated from 

our data indicates that kelpfish larvae could be transported sufficient distances to connect the 

local rocky habitat to areas north and south ofthe headlands mentioned above. The most common 

member of this genus found locally as an adult, crevice kelpfish (Gibbonsia montereyensis), is 

distributed from British Columbia to Baja California, making it unlikely that local impacts could 

affect the larger population. 

TENERA E9-055.0 5-323 Final 316(b) Demonstration 

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5.2.9 Kelpfishes 

Table 5.2.9-1. Estimated total annual entrainment (ET ) and standard error 

(SE(ET)) for kelpfish larvae from the three analysis periods. 

Analysis Period Er SE(ET) 

1) Oct 23, 1996-Sep 30, 1997 186,000,000 4,740,000 

2) Oct 1,1997-Sep 30, 1998 83,600,000 4,150,000 

3) Jul 1,1997-Jun 30, 1998 124,000,000 5,000,000 

Table 5.2.9-2. Estimated total annual adjusted entrainment (EAdj_T) and 

standard error (SE(EMJ_T ) ) for kelpfish larvae from the three analysis 

periods. 

Analysis Period EAdj_T SP(EMj_T) 

1) Oct 23, 1996-Sep 30, 1997 181,000,000 4,610,000 

.2) Oct 1, 1997-Sep 30, 1998 308,000,000 15,300,000 

3) Jul 1,1997-Jun 30, 1998 458,000,000 18,400,000 

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P.44 

5.2.9 Kelpfishes 

Table 5.2.9-3. Kelpfishes: Monthly estimates of proportional entrainment (PE, ) and annual 

proportion of larvae hatched in the hh survey period (fj) 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 PP SE(PE,) f SP(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 

0.0347 

0.250 

0.0298 

0.0357 

0.0239 

0.0160 

0.00836 

0.0148 

0.00144 

0.168 

0.346 

0.216 

0.0146 

0.122 

0.022 

0.0181 

0.0117 

0.00762 

0.00291 

0.00473 

0.00156 

0.114 

0.189 

0.122 

0.224 

0.172 

0.0668 

0.0329 

0.0307 

0.0206 

0.0466 

0.0229 

0.00948 

0.0468 

0.0815 

0.246 

0.00635 

0.00471 

0.00447 

0.00162 

0.00155 

0.00116 

0.00194 

0.00100 

0.000850 

0.00177 

0.00372 

0.00863 

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

Survey Start Date PE, SE(PE,) fi SP(f) 

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 

0.152 

0.168 

0.0417 

0.0612 

0.116 

0.0389 

0.0137 

0.0802 

0.0131 

0.190 

0.240 

0.277 

0.104 

0.0937 

0.0174 

0.0241 

0.0412 

0.00762 

0.00293 

0.0331 

0.00592 

0.0940 

0.113 

0.149 

0.0847 

0.0532 

0.0286 

0.0560 

0.129 

0.183 

0.0946 

0.103 

0.0351 

0.0762 

0.0989 

0.0580 

0.00336 

0.00270 

0.00199 

0.00259 

0.00283 

0.00426 

0.00253 

0.00286 

0.00140 

0.00200 

0.00288 

0.00240 

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P.45 

5.2.9 Kelpfishes 

ui 

ai 

E 

CO 

c 

CD 

o 

c 

CD 

CD 

Kelpfishes 

Survey Oate 

T designatessurveywithdensity=0 

Figure 5.2.9-1. Weekly mean larval density (#/m3 + 1 S.E.) at the DCPP intake. 

TENERA E9-055.0 5-326 Final 316(b) Demonstration 

March 1,2000 
m 

2 

m 

m 

CO 

o 

Ul 

Ut 

b 

3 

co 

g-cp 

-- Vt 

m+ 

N> Q> 

o ca-. 

o o 

O 3 

Kelpfishes 

cn 327 

CO 

E 

* 

0.84 

0.70 

0.56 

0.42 

0.28 

0.14 

0.00 

Depth Contours 

20 melees 

mmmmm 40 metefS 

mmmm 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 5.2.9-2a. Mean larval density (#/m3) collected in the DCPP study grid cells and at the entrainment sampling location. 

Ul 

io 

io 

2. 

TJ 

zn 

Vt 

ZT. 

CD 

CO 

J** 

0) 
m 

z 

m 

m 

CD 

• 

o 

cn 

m 

vco 

ro 

oo 

3 

CU 

CO 

CD 

§1 

to CU 

o t*. 

o o 

O 3 

Kelpfishes 

CO 

E 

0.84 

0.70 

0.56 

0.42 

0.28 

0.14 

0.00 

Depth Contours 

in 20 meters 

----m 40 meters 

•^••TM 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 5.2.9-2b (continued). Mean larval density (tf/m1) collected in the DCPP study grid cells and at the entrainment sampling location. 

cn 

ro 

co 

CD 

Vt 

ZT 

CD 

Vt 

tr ^1 
H 

m 

z 

m 

rn 

CO 

o 

Ul 

Ul 

co 

M 

CO 

T l 

5 ' 

co_ 

co 

at 

§1 

^ • * 

ro S 

O mt 

o o 

o 3 

Kelpfishes 

co 

0.84 

0.70 

0.56 

0.42 

0.28 

0.14 

0.00 

Depth Contours 

— — 20 meters 

• — 40 meters 

—mm 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 5.2.9-2c (continued). Mean larval density (#/m3) collected in the DCPP study grid cells and at the entrainment sampling location. 

cn 

ro 

CO 

2. 

•o 

vt 

CD 

Vt 

|5 
m 

z 

m 

m 

CO 

i 

o 

cn 

ui 

V 

CO 

CO 

o 

3 01 

co 

at 

M 

ro S 

o a: 

o o 

o 3 

Kelpfishes 

CO 

E 

0.84 

0.70 

0.56 

0.42 

0.28 

0.14 

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 5.2.9-2d (continued). Mean larval density (#/m3) collected in the DCPP study grid cells and at the entrainment sampling location. 

cn 

ro 

co 

2. 

• o 

3 1 

CA 

•T 

CD 

Vt 
P.50 

5.2.9 Kelpfishes 

Kelpfishes 

N= 7,331 

15 — 

-

-

of Occurrence 

0 

I I I I I I I I I 

Frequency 

IIIII I 

Percent 

IIIII I 

_ 

M i n 

Madia 

1 * % 

jl 

O | . . . | . . . | . 

2.2 3.2 4. 2 S.2 

C 

n Mean 

9 9 % 

. 

I 

I llllllll.ll..-. . I L. 

6.2 7.2 6.2 9.2 10.2 11.2 V 3 

M a x 

^ 

Length Category (mm) 

• • • i • • • i • • i • • • i • • • i i • • • • • M I 

*) A a 12 16 2 0 ZA 28 •*••*&-» 

Estimated age (days) 

Figure 5.2.9-3. 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 5-331 Final 316(b) Demonstration 

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I 

I 

1 

I 

I 

I 

I 

I 

I 

I 

I 

I 

1 

1 

I 

I 

I 

1 

I 
P.51 

5.2.9 Kelpfishes 

Kelpfishes 

15-

- Min 

10" 

o 

c

 5- I 

CD 

3 

O 

O 

O 

1% 

Entrainment: N=612 

Medianl Mean 

3.3 4.5 

>. 

" 15-

c 

CD 

3 

cr 

IV 

L. 

1 0 ~ 

c 

CD 

CJ 

Min 

1% 

99% 

Max 

P*P^T*^ 4 

10.8 *»*.% 

ledian 

Grid: N=311 

Mean 

99% 

3.3 4.5 5.8 

lllllll— 

Max 

i 

7.0 8.3 9.5 10.8 *-*\% 

Length Category (mm) 

Figure 5.2.9-4. 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 5-332 Final 316(b) Demonstration 

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P.52 

5.2.9 Kelpfishes 

^^ S.E -/+ Mea

n Density (#/m3 

0.24 — 

0.22 -E 

0.20 — 

0.18-E 

0.16 — 

0.14 -Z 

0.12 -. 

o.io-r 

0.08 ^ 

0.06-E 

0.04-E 

0.02-E 

o.oo — 

-

Kelpfishes 

i i i 

1990 1991 1992 

I 

I 

1993 

i 

1994 

Year 

-I 

i 

1995 

I 

I 

1996 

I 

1 

I 

1997 

i 

I 

1998 

Figure 5.2.9-5. 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 of data (December through June) 

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

TENERA E9-055.0 5-333 Final 316(b) Demonstration 

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5.2.9 Kelpfishes 

1.20 -

i.oe -

o.eeO.C*4~ 

0.72 -

£ o.eo — 

0.4 8 — 

0.3 « — 

0.2.4 — 

o.ooP a alongshor e 

! \ \ \ 

\ 

\ 

\ 

\ 

t 

t 

1 \ \ \ \ 

V 1 \ * \ 1 • \ 1 

\ 1 ^^^ 

V ! 

\l 

i . i 

—i—•—i—i—i—i—i—i — 

Kelpfishes - mean duration 

Analysis Period 3: Jul 1997-Jun 1998 

^.Pu- 0.318 

Estimate 

90% C.l. 

"~~~~~---_ 

—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—T—i—i—r-i—i—i—'—r 

Ox 

O km 

Sx . 

87 km 

lOx 

1*74 km 

-ISx 

2B1 km 

20x 

347 km 

2Sx 

434 km SOx 

S21 km 

3Sx 

BOS km 40x 

e s s km 

S U > of Population Relative to Study Oli d 

Equivalent Dlatanc a Alongshore 

Kelpfishes - mean duration 

Analysis Period 4: Jul 1998-Jun 1999 

90% C.l. 

Siz e of Population Relative tio Study Qrld 

Equivalent Diatanoe Alongshoro 

Figure 5.2.9-6a. Total annual entrainment mortality (\\) and 90% confidence interval (CL) as 

a function of die reciprocal of die fraction of die population at risk and contained in die study grid 

(ft.) used to approximate die alongshore extent of die study grid population expanded on die 

basis of alongshore current movements widi the 90% CI. indicated. 

TENERA E9-055.0 W34 Final 316(b) Demonstration 

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5.2.9 Kelpfishes 

Kelpfishes - maximum duration 

1.20 

1.08 -

o.se -

O.B4 -

0.72 -

J| o.eo — 

0.4B — 

0.3 6 

0.24 -

0.1 2 

o.oo — 

\ \ \ 

1 ^ 

: J 

l\ 

i \ 

* \ 

l\ 

i \ 

i \ 

1 \ 

i \ ! V 

i i r i | i • r 

&m alon g *»t">or*> 

•* I 

1 

N. 1 

v ! V 1 

•N. | 

v ; 

>. 1 ^x^ 

^**l —-

—1—1—1—1—1—1—1—1—1—1— 

Analysis Period 3: Jul 1997-Jun 1998 

^P* * = 0.410 

r—i—i—r i—i—i—r ' -

Estimate 

90% C.l. 

"""•"-- -

-i—i—i—i—i—i—i—i—i—i—i—i—i—r 1 

Ox 

O km 

Sx 

B7 k m 

lOx 

1 7 4 k m 

I Sx 

2S1 k m 

2 Ox 

3 4 7 k m 

28X 

4 3 4 km 

SOx 

S21 km S Sx 

eoe km 

40x 

SSS km 

Siz e of Population Relativ e to Study Orld 

Equivalent Diatanoe Alonaanor e 

Kelpfishes - maximum duration 

Analysis Period 4: Jul 1998-Jun 1999 

Estimate 

90% C.l. 

Siz e of Population Relative to Study Orld 

Equivalent Diatanoe Alongahor e 

Figure 5.2.9-6b. Total annual entrainment mortality (P^) and 90% confidence interval (CI.) as 

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

(j>s) used to approximate die alongshore extent of die study grid population expanded on the 

basis of alongshore current movements widi die 90% CI. indicated. 

TENERA E9-055.0 W35 Final 316(b) Demonstration 

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IT" P.55 

5.2.9 Kelpfishes 

o 

ta 

CO 

c 

co 

B "53 

E 

I 

o 

IO 

• * 

c 

CO 

V 

E 

Figu re 5.2.9-7. Mean number of kelpfishes observed per 50-meter subtidal transect in the 

DCPP RWMP South Control area. Spline smoothing algorithm used to draw the curve through 

the points. 

TENERA E9-055.0 5-336 Final 316(b) Demonstration 

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Blank Page 
5.2.10 Blackeye Goby 

5.2.10 Assessment of Blackeye Goby (Coryphopterus nicholsi) 

Coryphopterus nicholsi (Bean 1882); blackeye goby; length to 15 cm; northern 

British Columbia to south of Punta Rompiente, central Baja California; 

intertidal to 106 m; pale tan widi some brown or greenish speckling; small 

blue dot below eye (Miller and Lea 1972; Eschmeyer et al. 1983). 

The Gobiidae is the most speciose family of marine fishes with 1,875 species in 212 genera 

occurring worldwide in temperate to tropical climates and in a range of habitats from freshwater 

to brackish and marine environments (Brothers 1975; Nelson 1994). About 21 species and 16 

genera occur in the CalCOFI study area from the Oregon-California border to south of Cabo San 

Lucas, Baja California Sur, Mexico (Moser 1996). Adult blackeye goby (Coryphopterus nicholsi) 

is common in benthic nearshore marine environments in the vicinity of Diablo Canyon, generally 

at the rock-sand interface (Tenera unpubl. data; Miller and Lea 1972; Love 1996). 

The early life history of blackeye goby is similar to other members ofthe family Gobiidae. 

Females are oviparous, laying demersal, adhesive eggs under rocks that the males guard until 

planktonic larvae hatch (Love 1996; Moser 1996). Nests containing eggs are found from April to 

August in southern California (Wiley 1973). Larvae are reported to hatch at 2.8-3 mm (Moser 

1996), with planktonic durations of approximately 75 d (Steele 1997). Larval transformation 

occurs at 16-25 mm (Moser 1996), which is within the range of lengths at settlement 

(15-29 mm) reported by Steele (1997). Blackeye goby demonstrate protogynous 

hermaphroditism (Cole 1983; Breitburg 1987; Cole and Shapiro 1992), with all animals 

beginning life as females and transforming to males at around 6-7.5 cm (Love 1996). They live 

approximately 5 yr and mature around 0.5 yr at approximately 4.5 cm (Steele 1997). Spawning 

occurs year-round, peaking between February and October (Matarese et al. 1989; Moser 1996). 

Females may spawn several times per year with fecundity estimates ranging in southern 

TENERA E9-055.0 5-337 Final 316(b) Demonstration 

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P.58 

5.2.10 Blackeye Goby 

California from 1,700 eggs/nest (Ebert and Turner 1962) to 3,274-4,788 eggs in Orange County 

(Wiley 1973). 

While the size at age for post-larval blackeye goby has been described (Wiley 1973), size at age 

for the larvae estimated from planktonic duration and size at settlement are 2-3 mo and 15-29 

mm, respectively (Steele 1997). Additionally, larval growtii has been characterized for diree 

gobiid species (arrow goby: Clevelandia ios; cheekspot goby: Ilypnus gilberti; shadow goby: 

Quietula y-cauda) from Mission Bay, California (Brodiers 1975). Brothers (1975) described the 

growth coefficient of C. ios using the VBGF as k=0.96 (L.= 36 mm), that of I. gilberti as k=0.18 

(L«,= 60 mm), and that of Q. y-cauda as k=0.16 (L„= 70 mm). 

No species-specific larval survivorship estimates have been reported for blackeye goby. 

However, Brodiers (1975) calculated larval mortality up to settlement (to age 0 yr) for the diree 

sympatric gobiids (arrow goby, cheekspot goby, and shadow goby) from Mission Bay, California 

(Table 5.2-10-1). These estimates were used to approximate blackeye goby mortality for early 

life stages as well as post settlement juvenile and adult stages. Substituting the survivorship 

information for diese closely-related species into the assessment mediods allowed us to estimate 

the number of lost spawning females using FH and to project losses into the future as equivalent 

adults, using AEL. 

5.2.10.1 Summary of Field Collections 

Blackeye goby larvae were collected almost year round at die DCPP intake structure during the 

years 1996-1999 (Appendix H), with their highest densities occurring primarily between May 

and September (Figure 5.2.10-1). Blackeye goby larvae were more abundant in 1997 than in 

1998. This might have been due to the El Nino event that began during the spring of 1997 (Lynn 

et al. 1998; NOAA 1999). There were 7,658 larval blackeye goby identified from 1,119 bongo 

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

representing 24% ofthe subsamples processed from that location during that period. 

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5.2.10 Blackeye Goby 

Larval blackeye goby occurred in the DCPP study grid during most months except between 

February and March (Appendix H), with their highest density occurring during July 1997 

(Figure 5.2.10-2). Blackeye goby larvae were dispersed diroughout the study grid. However, 

during some months (e.g., October and November 1997, March 1999) blackeye goby larvae were 

abundant at the DCPP intake, but in low abundance in the study grid. There were 1,255 larval 

blackeye gobies identified from 505 bongo net subsamples representing 16% ofthe study grid 

subsamples collected and processed from July 1997-June 1999. 

Standard lengths of all blackeye goby larvae collected at the DCPP intake structure between 

October 1996 and June 1999 ranged from a minimum of 1.5 mm to a maximum of 5.1 mm 

(Figure 5.2.10-3). The growth rate of larval blackeye goby (0.27 mm-d'1) reported by Steele 

(1997) was used to estimate larval ages. Examining the central 98% of this length-frequency 

distribution resulted in minimum and maximum lengths for die analyses of 2 mm and 3.4 mm, 

respectively. The mean larval length in this distribution was 2.6 mm and was estimated to be 

approximately 2 d old. We assumed that larvae shorter than the minimum length ofthe central 

98% ofthe distribution were just hatched and assigned an age of 0 d. Reported hatching size 

range for this species is 2.8-3.0 mm (Moser 1996) however, indicating that the smallest larvae 

observed at DCPP represented either natural variation in hatch lengths within the population or 

the phenomenon of shrinkage following preservation (Theilacker 1980). Ifthe observed lengths 

are the result of natural variation in hatching lengths, then the possibility exists that all larvae 

from the observed minimum length of 1.5 mm to the greatest reported hatching length of 3.0 mm 

(Moser 1996) could have just hatched (aged-0 d), leading to overestimation of ages for all larvae 

<3.0 mm. The average estimated age at entrainment of ca. 2 d for blackeye goby larvae indicated 

that the power plant entrains relatively young larvae. 

There were significant differences between mean lengths (Mest: p < 0.001) and between lengthfrequency distributions (Kolmogorov-Smirnov test: p < 0.037) of larval blackeye goby from the 

DCPP intake structure and study grid despite the apparent similarity between the two 

distributions (Figure 5.2.10-4). The mean standard lengths from the intake and study grid were 

2.6 mm and 2.8 mm, respectively. The disparity between sample sizes (699 larvae from the intake 

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5.2.10 Blackeye Goby 

and 144 larvae from the study grid) may cause the t-test to be overly sensitive to slight 

differences between the means (Zar 1984). While these differences were statistically detectable 

and significant using the t-test and K-S test, we believe die biological significance of these 

differences was probably low. 

5.2.10.2 Estimating Total Annual Entrainment 

The annual estimated mean entrainment of larval blackeye gobies for the 1996-97 Analysis 

Period 1 (E~T = 138,000,000 ;SE =14,100,000) and 1997-98 Analysis Period 2 

(E^ = 133,000,000 ; SE=13,300,000) were extremely close in value (Table 5.2.10-2). The 

estimate for Analysis Period 3 differs from the other estimate for 1997-98, Analysis Period 2, 

because larval blackeye gobies were collected diroughout die year, including the time period that 

does overlap between die two periods (Figure 5.2.10-1). Values of ±2 SE(ET) can be used to 

approximate 95% confidence intervals around die point estimates. These approximate confidence 

intervals overlapped, indicating that die apparent differences between them were probably not 

statistically significant. 

Annual estimates ofthe number of entrained blackeye goby larvae, adjusted to die nine year 

average estimated from Intake Cove surface plankton tow sampling (Figure 5.2.10-5), were 

128,000,000 (SE=13,100,000) for Analysis Period 1 and 109,000,000 (SE= 10,900,000) for 

Analysis Period 2 (Table 5.2.10-3). The adjustment index (111,) was calculated as the ratio 

between the nine year average (/ ) of Intake Cove plankton samples and die average annual 

index estimated from these same tows during the year being adjusted (/,). The average index for 

the years 1997 and 1998 (I,) are 0.0181 and 0.0206 larvae/m3, respectively, while the long-term 

average index (7) is 0.0168 larvae/m3 for the years 1990-1998, yielding the ratio III, = 0.925 

for 1997 and 0.816 for 1998. The confidence intervals, estimated from ±2-SE(EAdJ_T), around 

the adjusted entrainment abundance overlap, indicating that the differences between the estimates 

are probably not statistically significant. 

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5.2.10 Blackeye Goby 

5.2.10.3 Fecundity Hindcasting (FH) 

Larval mortality rates were not available for blackeye goby, but Brothers (1975) indicates that 

99% mortality over two months is*reasonable for low fecundity gobies. Finite survivorship for 

blackeye goby larvae was estimated as 0.926-d'1 from Brothers (1975) who examined three 

sympatric goby species (arrow, cheekspot, and shadow goby). Average age at entrainment of 

blackeye gobies at DCPP was estimated as 2.12 d, calculated using minimum size ofthe central 

98% distribution (2 mm), mean size at entrainment (2.6 mm), and a growth rate of 0.27 mm-d'1 

(Steele 1997). Survival to entrainment is then estimated as 0.9262 n = 0.850. Lifetime fecundity 

(TLF) is calculated using a longevity of 3.6 yr estimated from the von Bertalanffy growth 

function (VBGF; Ricker 1975) described below, an age at first maturation of 0.5 yr (Steele 1997), 

and an estimated annual fecundity of 8,062 eggs (2 batches of 4,031 annually; Wiley 1973). The 

VBGF was used to estimate longevity of females at their transformation length from female to 

male. Steele'(1997) indicates that blackeye gobies mature at 0.5 yr (ca. 4.5 cm), and Love (1996) 

indicates that the largest fish recorded was ca. 15 cm; longevity is five years (Wiley 1973). The 

VBGF can be formulated as 

L,=Lm(\-e-kl), 

where 

L, = fish length at timet, 

Lr = theoretical maximum fish length (Lx assumed to be 15 cm), and 

k = growth coefficient. 

Then, using a length at maturity of approximately 4.5 cm and U- = 15 cm, k = 0.1724, the VBGF 

estimated an age of 3.6 yr based on a length of transformation from female to male of 7 cm SL. 

The adjusted total larval entrainment for blackeye goby (EAdj_T) was used to estimate the number 

of breeding females needed to produce the number of larvae entrained. The estimated number of 

breeding females (FH ) whose fecundity equals the estimated total loss of entrained larvae is 

calculated assuming age of maturation of 0.5 yr and longevity value of 3.6 yr. The number of 

adult females hindcast from the larvae entrained at DCPP was greater for Analysis Period 1 

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5.2.10 Blackeye Goby 

(FH = 12,000; SE =23,900) than for Analysis Period 2 (FH = 10,300; SE =20,300) (Table 

5.2.10-4). 

Sensitivity Analysis 

Longevity had the greatest leverage on recalculated values of FH (Table 5.2.10-5). Varying this 

parameter in the model resulted in an FH range of 4,750-192,000 adult females for 1996-97 

and 1997-98 analysis periods, compared to die original estimate of 10,300-12,100 adult females. 

Fecundity and larval survivorship had die next greatest amount of leverage on recalculated FH. 

5.2.10.4 Adult Equivalent Loss (AEL) 

No independent estimate of survival of blackeye goby from entrainment to age of adults was 

found in the literature. Therefore, we used survival estimates for AEL from two goby species 

(cheekspot and shadow goby) presented by Brodiers (1975). Blackeye goby larval survival from 

entrainment up to settlement was estimated starting at estimated average entrainment age (2.12 d) 

to 75 d at settlement (Steele 1997), using daily survival of 0.926 derived from Brothers (1975). 

Larval survivorship over tiiis period was calculated as 0.926^2.9 » 0.004. Juvenile and adult 

survivorship was estimated to 2 yr of age, which is die average age of adults assuming linear 

survival from 0.5 (age of first reproduction) to 5 yr (longevity). Daily finite survivorship was 

estimated as e~

x 02/36S

 = 0.997 using annual instantaneous mortality = 1.02 (Brodiers 1975). 

Survivorship from settlement to adulthood (2 yr less die 75 d of planktonic duration) is then 

0.997656 « 0.159. 

The adjusted total larval entrainment for blackeye goby (PAdj.T ) was used to estimate the number 

of equivalent adults lost to the population based on the estimated number of larvae entrained 

(Table 5.2.10-6). The estimated number of equivalent adults corresponding to the number of 

larvae entrained at DCPP was 75,200 (SE =220,000) for Analysis Period 1 and 64,100 

(SE =188,000) for Analysis Period 2. Because blackeye gob}' are protogynous hermaphrodites, 

we do not assume that,4£Z is related to FH by a factor of two since we cannot assume a 50:50 

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5.2.10 Blackeye Goby 

sex ratio in the adult population. The magnitude ofthe SE for the two estimates indicates that the 

differences between analysis periods are not statistically significant. 

Sensitivity Analysis ' 

Early larval and early juvenile survivorship had the greatest leverage on recalculated values of 

AEL (Table 5.2.10-7). Varying either of these parameters in the model resulted in an AEL 

range of 12,400-390,000 adult equivalents for the 1996-97 and 1997-98 analysis periods, 

compared to the original estimate of 64,100-75,400 adult equivalents. The range of estimates of 

entrainment had less effect on estimated AEL. 

5.2.10.5 Empirical Transport Model (ETM) 

Monthly estimates of proportional entrainment (PE,) for blackeye goby in each /th survey from 

the two years sampled ranged from a minimum of zero to a maximum of 0.859±0.543 

(l SE^PE,)) in February 1998 and March 1999 (Table 5.2.10-8). 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 (fj) were equal to zero (e.g., February 1999). When PE, = 0 and 

f>0 (e.g., March 1998), 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. For blackeye goby, 

the relatively large PE, for February 1998 and March 1999 resulted from the fact that no 

blackeye goby larvae were collected in the study grid. This PE, was calculated using the larval 

density from the weekly entrainment sample (Appendix H) multiplied by the unsampled volume 

inshore ofthe two cells nearest the intake (Dl and El) to approximate the number of larvae in 

this volume. This number was then added to the number of larvae found in cells Dl and El, zero 

in this case as well as elsewhere in the grid, to approximate the number of larvae in the whole 

study grid. The low / values associated with these PE, 's indicated that few larval blackeye 

gobies were collected at the intake structure during the survey period and that these estimates had 

low weights attributed to them in calculating the annual estimate of entrainment mortality. The 

greatest abundances of blackeye goby larvae at the intake structure occurred from July through 

September or October of each year as indicated by the higher values of / during those months. 

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5.2.10 Blackeye Goby 

Empirical transport modeling results for blackeye goby (PM ) show the effects of low estimated 

larval durations (Figure 5.2.10-6). Blackeye goby larvae were collected throughout the study 

grid, and thus, Ps was calculated by using alongshore and onshore current movement over 

estimated larval entrainment ages; study grid estimates ofthe number of blackeye goby larvae 

were extended alongshore or were extrapolated offshore, based on study grid abundance patterns 

offshore, and then extended alongshore. Alongshore larval transport over the short larval 

durations estimated from entrained larvae (average of 2 d to maximum of 5 d old at entrainment) 

resulted in low estimates ofPs . Consequently, estimates of PM over these small extrapolated 

areas were high. Estimates of PM were reasonably similar between the two analysis periods for 

either larval duration (mean or max.), whether extending Ps only alongshore or extrapolating 

offshore and then extending alongshore. The alongshore PM value ranged from 0.174 to 0.228, 

while the extrapolated PM values range from 0.079 to 0.179. 

5.2.10.6 Interpretation of Assessment Results 

Blackeye goby does not support a commercial or recreational fishery, and there is little 

information on their ecological role in the community. However, there are some indications of 

their importance as forage for other species (e.g., cormorants: Love 1996). Because ofthe 

absence of any fishery for this species, there are no catch data that can be used to compare 

harvest mortality rates to entrainment mortality rates (PM ) or to estimated FH and AEL values. 

Results of ETM modeling show that the power plant may annually entrain approximately 17-23% 

ofthe blackeye goby larvae from an area approximately twice that ofthe study grid. Fecundity 

hindcast estimates indicate that these values ofPM may be equal to predicted losses ofthe 

reproductive output of about 10,000-12,000 adult females. An independent estimate of AEL 

yields a predicted loss of 64,000-75,000 adults (males and females combined). Blackeye gobies 

are protogynous hermaphrodites (Cole 1983; Breitburg 1987; Cole and Shapiro 1992) and there 

is no reason to assume that the adult population for this species reflects a 50:50 sex ratio that 

would to required for the relationship of AEL = 2FH . Although both of these estimates are 

relatively large the local population of adult blackeye goby does not exhibit any long-term 

declines based on DCPP Receiving Water Monitoring Program studies on subtidal fishes (Figure 

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5.2.10 Blackeye Goby 

5.2.10-7: Tenera 1997c). The time period since power plant operation began is much greater than 

the relatively short life-span (~5 yr) of blackeye gobies, indicating that there has probably been 

sufficient time for power plant effects to become apparent for this species. 

The Intake Cove surface plankton tows were also analyzed to determine if any declining trends in 

larval production could be detected. These data were only analyzed for the period December 

through June. Blackeye goby larvae were present in the intake cove samples collected during 

December through June, but were also abundant in the.entrainment subsamples collected from 

July through September. Therefore, the index based on these data that was used to adjust annual 

entrainment estimates to the long-term average may not be a good estimator for blackeye goby. 

There is no way to estimate how the index would have changed if based on an entire 12 mo 

period. Nonetheless, the Intake Cove surface plankton tows data do not show any declining 

trends in annual mean larval blackeye goby densities and larval densities in 1997 and 1998 were 

greater than the nine year average(Figure 5.2.10-5). 

• , 

Estimates of total annual entrainment mortality (PM ) for this species were relatively high among 

the target fish taxa examined (ca. 13-23%). These values are based on extending the larval 

abundance within the study grid alongshore (or extrapolating that abundance offshore and then 

extending it alongshore) using estimated larval duration at entrainment. The short estimated 

larval durations for this taxa resulted in relatively small estimated areas for the population at risk 

These small population areas are representative ofthe reflects the small size range for the 

majority of entrained larvae (2.0-3.4 mm). This size range is well below the reported range at 

flexion of 5.8-6.8 mm (Moser 1996). In fact, our observed minimum larval lengths were less 

than reported hatching lengths in the literature, which may be due to natural variation in hatching 

lengths plus an undetermined contribution of larval shrinkage due to preservation (Theilacker 

1980). This may indicate that our assumption that age-0 d larvae correspond to our minimum 

99% larval length is inaccurate and that all larvae less than maximum reported hatching length of 

3.0 mm (Moser 1996) were aged-0 d. This would further reduce our estimate of larval duration 

and population area. While the small areas based on these short larval durations and alongshore 

and onshore current movements lead, in part, to the high estimates of entrainment mortality, the 

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5.2.10 Blackeye Goby 

size ofthe entrained larvae indicate that the time the larvae are exposed to entrainment is very 

short. The lack of apparent declines in the local adult and larval populations over several 

generations since power plant startup indicates that entrainment mortality may only be affecting 

surplus larval production that would not lead to a reduction in the local population. This could 

also indicate that compensation is occurring at some later stage in development. In either case, it 

does not appear the DCPP cooling water intake is causing a long-term decline in the local 

population of blackeye goby. 

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5.2.10 Blackeye Goby 

Table 5.2.10-1. Larval mortality statistics for three sympatric gobiids from Mission Bay, 

California (Brothers 1975). 

Species 

Clevelandia ios 

Ilypnus gilberti 

Quietula y-cauda 

Two^-Month Larval 

Mortality Rates 

(to settlement) 

% (Finite) 

98.3 

98.6 

99.2 

Annual PostSettlement 

Mortality Rates 

% (Finite) 

89-91 

66-74 

62-69 

(Instantaneous) 

-2.39 

-1.08 

-0.96 

Table 5.2.10-2. Estimated total annual entrainment (ET ) and standard error 

(SE(ET )) for blackeye goby (Coryphopterus nicholsi) larvae from the three 

analysis periods. 

Analysis Period SE(ET) 

1) Oct 23, 1996-Sep30, 1997 138,000,000 

2) Oct 1, 1997-Sep 30, 1998 133,000,000 

3) Jul 1, 1997-Jun 30, 1998 157,000,000 

14,100,000 

13,300,000 

14,600,000 

Table 5.2.10-3. Estimated total annual adjusted entrainment (EAdJ_T) and 

standard error (SE(EAdJ_T)) for blackeye goby (Coryphopterus nicholsi) 

larvae from the three analysis periods. 

Analysis Period ^Adj-T 

1) Oct 23, 1996-Sep 30, 1997 128,000,000 

2) Oct 1, 1997-Sep30, 1998 109,000,000 

3) Jul 1, 1997-Jun 30, 1998 128,000,000 

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SE(EM.T) 

13,100,000 

10,900,000 

11,900,000 

Final 316(b) Demonstration 

March 1,2000 
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5.2.10 Blackeye Goby 

Table 5.2.10.-4. Estimated number of blackeye goby adult (Coryphopterus nicholsi) 

females (FH) whose reproductive output was equivalent to the adjusted number of 

larvae entrained per year (EAdj_T) at Diablo Canyon Power Plant including the 

standard error ofthe estimate (SE(FH)) and 90% confidence limits (C.L.). 

Analysis Period 

Upper Lower 

FH SE(FH) 90% C.L. 90% C.L. 

1) Oct 23, 1996-Sep 30, 1997 

2) Oct 1,1997-Sep 30,1998 

3) Jul 1, 1997-Jun 30, 1998 

12,000 23,900 315,000 461 

10,300 20,300 268,000 393 

12,100 24,000 316,000 462 

Table 5.2.10-5. Blackeye goby (Coryphopterus nicholsi): Sensitivity analysis for 

FH from the three analysis periods recalculated for each model input parameter (0): 

pAdj-T ± I64 5 SE(0); other parameters are 0.e

±l645CyW whereCV(0)= l.Oor 100%. 

a) Analysis Period 1: October 1, 1996-September 30, 1997 

Parameter 

FH = 

pAdj-T 

S larvae 

U Eggs/yr 

Longevity 

Maturation 

Estimate 

= 12,000 

128,000,000 

0.850 

8,060 

3.60 

0.5 

Minimum 

10,000 

10,200 

2,320 

5,570 

11,100 

Recalculated FH 

Maximum 

14,100 

62,400 

62,400 

192,000 

14,400 

Range 

4,050 

52,200 

60,100 

186,000 

3,210 

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__„..--, 

5.2.10 Blackeye Goby 

Table 5.2.10-5 (continued). Blackeye goby (Coryphopterus nicholsi): Sensitivity analysis 

for FH from the three analysis periods recalculated for each model input parameter (0): 

P-Adj-T ± 1 -

6 4 5

 SE0); other parameters are ff.g±iM5CV0) where CV( 0) = 1.0 or 100%. 

b) Analysis Period 2: October 1, 1997-September 30, 1998 

Parameter 

FH = 

E 

^Adj-T 

S larvae 

# Eggs/yr 

Longevity 

Maturation 

Estimate 

= 10,300 

109,000,000 

0.850 

8,060 

3.60 

0.5 

Minimum 

8,580 

8,710 

1,980 

4,750 

9,490 

Recalculated FH 

Maximum 

11,900 

53,100 

53,100 

163,000 

12,200 

Range 

3,370 

44,400 

51,200 

158,000 

2,740 

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

Parameter 

FH = 

pAdj-T 

Slarvae 

# Eggs/yr 

Longevity 

Maturation 

Estimate 

12,100 

128,000,000 

0.850 

8,060 

3.60 

0.5 

Minimum 

10,200 

10,300 

2,330 

5,590 

11,200 

Recalculated FH 

Maximum 

13,900 

62,600 

62,600 

192,000 

14,400 

Range 

3,690 

52,300 

60,200 

187,000 

3,220 

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5.2.10 Blackeye Goby 

Table 5.2.10-6. Estimated number of equivalent blackeye goby (Coryphopterus 

nicholsi) adults (AEL) equal to the adjusted number of larvae entrained per year 

(EAdj_j) at Diablo Canyon Power Plant including the standard error ofthe estimate 

(SE(AEL)) and 90% confidence limits (C.L.). 

Analysis Period 

Upper Lower 

AEL SE(AEL) 90% C.L. 90% C.L. 

1) Oct 23, 1996-Sep 30, 1997 75,200 220,000 9,260,000 611 

2) Oct 1, 1997-Sep 30, 1998 64,100 188,000 7,890,000 521 

3) July 1, 1997-June 30, 1998 75,400 221,000 9,290,000 613 

Table 5.2.10-7. Blackeye goby (Coryphopterus nicholsi): Sensitivity analysis for AEL 

from the three analysis periods recalculated for each model input parameter (0): EAdJ_T

 ± 

1.645 SE(0); other parameters are ff.gtiMScrtf) where CV(0)= 1.0 or 100%. 

a) Analysis Period 1: October 1, 1996-September 30, 1997 

Parameter Estimate 

AEL = 75,200 

EAdJ_T 128,000,000 

S early larvae 

S early 

juvenile 

Minimum 

87,900 

390,000 

390,000 

Recalculated AEL 

Maximum 

, 

62,600 

14,500 

14,500 

Range 

25,300 

375,000 

375,000 

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5.2.10 Blackeye Goby 

Table 5.2.10-7 (continued). Blackeye goby (Coryphopterus nicholsi): Sensitivity analysis 

for AEL from the three analysis periods recalculated for each model input parameter (0): 

PA^-T ± 1-645 SE(0); other parameters are g.^\MScr(d) whereCV(0)= 1.0 or 100%. 

b) Analysis Period 2: October 1, 1997-September 30, 1998 

Parameter Estimate 

AEL =64,100 

P-Adj-T 109,000,000 

S earlylarvae 00037 2 

S early ° 1 5 8 

juvenile 

Minimum 

74,600 

332,000 

332,000 

Recalculated AEL 

Maximum 

53,600 

12,400 

12,400 

Range 

21,000 

320,000 

320,000 

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

Parameter Estimate 

AEL = 75,400 

EAdj_T 128,000,000 

S early larvae 00037 2 

S early ° 1 5 8 

juvenile 

Minimum 

87,000 

391,000 

391,000 

Recalculated AEL 

Maximum 

63,900 

14,600 

14,600 

Range 

23,100 

376,000 

376,000 

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5.2.10 Blackeye Goby 

Table 5.2.10-8. Blackeye goby (Coryphopterus nicholsi): Monthly estimates of 

proportional entrainment (PE,) and annual proportion of larvae hatched in the ith survey 

period (fj) 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 

b) Analysis Period 4: July 1, 

Survey Start Date 

Jul 21,1998 

Aug 26, 1998 

Sep 16, 1998 

Oct 6, 1998 

Nov 11, 1998 

Dec 9, 1998 

Jan 12, 1999 

Feb 3, 1999 

Mar 17, 1999 

Apr 14, 1999 

May 24, 1999 

June 23, 1999 

TENERA E9-055.0 

PE, 

0.0141 

0.0353 

0.0398 

0.452 

0.291 

0.0658 

0.0512 

0.859 

0 

0.859 

0.291 

0.202 

1998-June 30, 

PE, 

0.0377 

0.0130 

0.00747 

0.0186 

0.167 

0.0575 

0.0297 

0 

0.859 

0.395 

0.0164 

0.0125 

SE (PE,) 

0.00798 

0.0130 

0.0172 

0.288 

0.185 

0.0332 

0.0270 

0.543 

0 

0.361 

0.130 

0.111 

1999 

SE(PE,) 

0.0167 

0.00539 

0.00370 

0.00953 

0.148 

0.0514 

0.0413 

0 

0.504 

0.217 

0.00620 

0.00555 

5-352 

fi 

0.206 

0.219 

0.143 

0.0390 

0.0524 

0.0174 

0.0447 

0.0140 

0.00172 

0.0368 

0.0854 

0.140 

f 

0.160 

0.182 

0.0687 

0.153 

0.0903 

0.00879 

0.00163 

0 

0.0755 

0.0837 

0.0806 

0.0955 

SP(f) 

0.0187 

0.0140 

0.0127 

0.00500 

0.00554 

0.00160 

0.00556 

0.00150 

0.000310 

0.00285 

0.00667 

0.0119 

SP(f) 

0.0115 

0.0131 

0.0122 

0.0236 

0.0118 

0.00118 

0.000310 

0 

0.00730 

0.00785 

0.00555 

0.00862 

Final 316(b) Demonstration 

March 1,2000 
P.73 

5.2.10 Blackeye Goby 

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T designates survey with density =0 

Figure 5.2.10-1. Weekly mean larval density (#/m3 + 1 S.E.) at the DCPP intake. 

TENERA E9-055.0 5-353 Final 316(b) Demonstration 

March 1,2000 
m 

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Depth Contours 

HI 20 meters 

• — 40 meters 

H M > 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 5.2.10-2a. Mean larval density (#/mJ) collected in the DCPP study grid cells and at the entrainment sampling location. 

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Depth Contours 

<—TM~ 20 meters 

«•—1» 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 5.2.10-2b (continued). Mean larval density (#/m3) collected in the DCPP study grid cells and at the entrainment sampling location. 

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P.76 

5.2.10 Blackeye Goby 

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TENERA E9-055.0 5-356 Final 316(b) Demonstration 

March 1.2000 
m 

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0.16 

0.12 

0.08 

0.04 

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 5.2.10-2d (continued). Mean larval density (#/m3) collected in the DCPP study grid cells and at the entrainment sampling location. 

k» 

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P.78 

5.2.10 Blackeye Goby 

Blackeye goby (Coryphopterus nicholsi) 

N=4,812 

2 0 — 

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Occurrence 

01 

1 1 1 1 1 1 1 1 1 

*o - Frequency m 0 

1 1 1 1 1 1 1 1 

Percent 

01-

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Moan Median 

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Length Category (mm) 

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Estimated age (days) 

H - p 

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t~ 

1 1 1 

-» * « 

Figure 5.2.10-3. 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 5-358 Final 316(b) Demonstration 

March 1,2000 
p ". -J 

P.79 

5.2.10 Blackeye Goby 

25—I 

20 — 

15" 

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Blackeye goby (Coryphopterus nicholsi) 

Entrainment: N=699 

1% 

Median Mean 

99% 

Grid: N=144 

Min 

1 % 

Median Mean 

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Length Category (mm) 

Figure 5.2.10-4. 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 5-359 Final 316(b) Demonstration 

March 1.2000 
P.80 

5.2.10 Blackeye Goby 

ai 

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0.008 -E 

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Blackeye gob) r (Coryp hopterus nicholsi) 

I : 

i 

1990 1991 1992 1993 1994 

Year 

1995 1996 1997 1998 

Figure 5.2.10-5. 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 of data (December through June) 

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

TENERA E9-055.0 5-360 Final 316(b) Demonstration 

March 1,2000 
5.2.10 Blackeye Goby 

P.81 

Blackeye goby (Coryphopterus nicholsi) - mean duration 

Analysis Period 3: Jul 1997-Jun 1998 

Estimate 

90% C.l. 

Sx lO x IS x 20 x 2B x SOx SSx 40 x 

8 7 km IT * Km 261k m 347 km 434kf n 621k m SOB km BOS km 

Siz e of Population Relative to Study Orld 

Equivalent Diatanoe Alongahore 

Blackeye goby (Coryphopterus nicholsi) • mean duration 

Analvsis Period 4: Jul 1998-Jun,}999 

Estimate 

90% C.l. 

P« = 0.174 

P* = 0.163 ±0.207 

20x S«7 km SOx 

S 2 1 k m 

SSx SOB km 

40x 

BBS km 

81a » of Population Relative to Study Orld 

Equivalent Diatanoe Alonoenore 

Figure 5.2.10-6a. Total annual entrainment mortality (PM) and 90% confidence interval (CI.) as 

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

(j>s) used to approximate die alongshore extent ofthe study grid population expanded on die 

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

extended alongshore using bodi onshore and alongshore current movements with 90% C J.'s 

indicated. 

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March 1,2000 
P.82 

5.2.10 Blackeye Goby 

Blackeye goby (Coryphopterus nicholsi) - maximum duration 

Analysis Period 3: Jul 1997-Jun 1998 

Estimate 

90% C.l. 

Ox 

O k m 

Sx 

B 7 k m 

l O x IS x 20 x 2S x 

1 7 4 k m 2S 1 k m 34 7 k m 43 4 k m 

SOx 

S 2 1 k m 

SSx 

SOB k m 

4 0 x 

ees km 

Six * o f Populatio n Relativ e t o Stud y Orl d 

Equivalen t Diatano e Alongahor e 

Blackeye goby (Coryphopterus nicholsi) - maximum duration 

Analysis Period 4: Jul 1998-Jun 1999 

Estimate 

90% C.l. 

Sx 

B 7 k m 

l Ox 

1 7 4 k m 

I S x 

2 S 1 k m 

2 0 x 

3 4 7 k m 

2 S x 

4 3 4 k m 

3 0 x 

S 2 1 k m 

SSx 40 x 

BOB k m BOS k m 

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

Equivalen t Diatano e Alongshor e 

Figure 5.2.10-6b. Total annual entrainment mortality (Pu) and 90% confidence interval (CI.) 

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

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

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

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

indicated. 

TENERA E9-055.0 5-362 Final 316(b) Demonstration 

March 1.2000 
P.83 

-*H1 

5.2.10 Blackeye goby 

o 

0 

0) 

c 

CO 

CD 

V 

E 

I 

o 

LO 

c 

CO 

CD 

E 84 : 86 

Plant Start-up Year 

Figure 5.2.10-7. Mean number of blackeye gobies observed per 50-meter subtidal 

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

draw the curve through the points. 

TENERA E9-055.0 5-363 Final 316(b) Demonstration 

March 1,2000 
P.84 

Blank Page 
P.85 

5.2.11 Flatfishes 

5.2.11 Assessment of Flatfishes (Family Paralichthyidae) 

Left-eyed flatfishes (Paralichthyidae) are represented in the California Current region by 8 genera 

and 19 species (Nelson 1994; Moser and Sumida 1996). The larvae of four sanddab species 

(genus Citharichthys) are abundant in CalCOFI tows up to 180 km offshore, while other 

paral ichthy id flatfish such as the California halibut (Paralichthys californicus) are primarily 

found within 40 km of shore. Females in this family are oviparous with large batch sizes and 

multiple spawns. Spawning takes place throughout the year with seasonal peaks. DCPP 

entrainment effects on larvae were assessed for sanddabs (Citharichthys spp.) and for California 

halibut. 

5.2.11.1 Sanddabs (Citharichthys spp.) 

Citharichthys stigmaeus Jordan and Gilbert 1882; speckled sanddab; length to 17 cm; 

Prince William Sound, Alaska to Bahia Magdalena, southern Baja California; 

nearshore to 607 m; eyed side brown or tan with black speckles and spots; blind side 

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

Citharichthys sordidus (Girard 1854); Pacific sanddab; length to 41 cm; Sea of Japan to 

Bering Sea to Cabo San Lucas, southern Baja California; 0-549 m (Miller and Lea 

1972; Eschmeyer et al. 1983); eyed side light brown, mottled with dark brown 

sometimes with yellow and orange spots; blind side whitish or light tan (Eschmeyer 

etal. 1983). 

Citharichthys species, including the speckled and Pacific sanddabs, are commercially fished and 

generally found over sandy bottom, with the speckled sanddab generally found in shallow water 

bays and estuaries (Moser 1996; Rackowski and Pikitch 1989). Sanddab females are oviparous, 

TENERA E9-055.0 5-364 Final 316(b) Demonstration 

March 1,2000 
P.86 

5.2.11 Flatfishes 

producing planktonic eggs and larvae (Moser 1996). According to Moser (1996), both species 

spawn year-round in the CalCOFI area with their highest abundance during the periods AugustDecember for speckled sanddab, and January-February plus August-October for Pacific 

sanddab. In southern California, Goldberg and Pham (1987) found that speckled sanddab spawn 

March-October, while Ford (1965) reported that Pacific sanddabs spawn mainly from AprilSeptember. 

Longevity and reproduction have been investigated in both species of sanddabs. Ford (1965) 

found that female speckled sanddabs begin to spawn in their second year and can produce up to 

three batches of eggs per year. They may produce 1,000-6,000 eggs per batch and may live over 

4 yr (Ford 1965; Table 5J.11-1). Some female Pacific sanddabs first mature at 2 yr (Smith 

1936). Half of the older females are mature by 3 yr and all are mature by 4 yr (Arora 1951). Total 

lifespan may be over 11 yr (Love 1996). No estimates of annual egg production have been 

reported. 

Both species of sanddabs can have extended planktonic durations. Sakuma and Larson's (1995) 

review reports that speckled sanddab (Citharichthys stigmaeus) larvae may be planktonic up to 

324 d, while the Pacific sanddab (Citharichthys sordidus) may remain in the plankton for 271 d. 

Kendall (1992) found that speckled sanddabs probably settle after 113-324 d. Settlement sizes 

for speckled and Pacific sanddabs are 35 mm and 40 mm, respectively (Moser 1996). Larval 

growth rate of Citharichthys spp., mainly Pacific sanddab, for age-0 yr individuals was 0.19-0.30 

mm/d, and the monthly instantaneous mortality rate was 0.437 in 1983 and 0.176 in 1984 (Rogers 

1985). Speckled sanddab mortality during the egg and larval period is nearly 99.9% (Ford 1965; 

Table 5.2.11-1). 

Summary of Field Collections 

Sanddab larvae were collected at the DCPP intake structure during two periods: a minor pulse 

during December-March and a stronger pulse during July-September in all years 1996-1999 

(Appendix H). Their highest density occurred in early August 1997 (Figure 5.2.11-1). The 

density during July-September 1998 was lower than during the same months in 1997, possibly 

TENERA E9-055.0 5-365 Final 316(b) Demonstration 

March 1,2000 
P.87 

5.2.11 Flatfishes 

due to the El Nino event that occurred during the fall-winter seasons spanning 1997-98 (Lynn et 

al. 1998; NOAA 1999). There were 254 sanddabs identified from 170 bongo net subsamples 

representing 3.5% ofthe entrainment subsamples collected and processed from that location 

during this period. Ofthe total number identified from the entrainment subsamples, 113 were 

Pacific sanddabs, 71 were speckled sanddabs, and 70 were only identifiable to the generic level. 

Sanddab larvae, notably C. stigmaeus, occurred year-round in the study grid (Appendix H), with 

their greatest density occurring during July 1997 and 1998 (Figure 5.2.11-2). The spatial 

distribution of sanddab larvae in the grid was inconsistent between surveys. Generally, they were 

collected farther from shore, except large numbers collected inshore in July 1997. There were 

361 larval sanddabs identified from 43 bongo net subsamples representing 1% ofthe study.grid 

subsamples collected and processed. Ofthe total number identified from the grid subsamples, 

142 were Pacific sanddabs, 156 were speckled sanddabs, and 63 were identifiable to only die 

generic level.' 

Standard lengths of sanddab larvae in entrainment subsamples between October 1996 and June 

1999 ranged from 1.3 mm to 32 mm (Figure 5.2.11-3). Only one larvae measuring 32 mm was 

collected; the next largest individual was 3.5 mm. The central 98% ofthe sanddab lengthfrequency distribution resulted in minimum and maximum lengths for the analyses of 1.3 mm and 

3.5 mm, respectively. The growth rate of larval sanddabs (0.20 mm/d) reported by Kendall 

(1992) and Sakuma (1995) was used to estimate larval ages. The mean larval length in this 

distribution was 2.61 mm and approximately 6.5 d of age. The reported hatch length for C. 

stigmaeus is about 1.3 mm and less than 2.6 mm for C. sordidus (Moser 1996). 

Lengths of sanddab larvae were collected for paired DCPP intake and study grid subsamples 

(Figure 5.2.11-4). However, very few measurable larvae occurred in the coincident subsamples: 

4 at the DCPP intake and 52 in the study grid. These low sample sizes precluded statistical 

analyses and render difficult even qualitative comparisons between the two length distributions. 

TENERA E9-055.0 5-366 Final 316(b) Demonstration 

March 1.2000 
P.88 

5.2.11 Flatfishes 

Estimating Total Annual Entrainment 

The annual estimated mean entrainment and associated standard error for sanddab larvae show 

that few larval sanddabs were entrained (Table 5.2.11-2). Estimated entrainment was greater in 

1996-97 Analysis Period 1 (E^ = 7,160,000; SE = 702,000) than in 1997-98 Analysis Period 2 

(ET = 1,540,000; SE = 283,000). The high larval abundance observed in summer 1997 produced 

die highest entrainment estimates. The apparent difference between the estimates for Analysis 

Period 2 (October 1997-September 1998) and Analysis Period 3 (July 1997-June 1998) 

illustrates the sensitivity of unadjusted annual entrainment estimates to die time period selected 

and to episodic oceanographic events. The estimates for these two periods were identical or very 

close in value for most target taxa. The estimated entrainment values for the analysis periods 

were not adjusted by the long-term weekly Intake Cove surface plankton tows (December-July), 

because sanddab spawning occurred mainly after die 7 mo surface tow period used for analysis 

(Figure 5.2.11-5). 

Fecundity Hindcasting (FH) 

Both FH and AEL mediods required age-specific mortality, and FH required fecundity to assess 

entrainment effects. Egg and larval survival rates were estimated using Ford's (1965) estimate of 

0.0015 survival through the first 90 d based on examination of fecundity, number of females, and 

transformed juveniles (Table 5.2.11-1). The calculated egg and larval daily survival was 0.930/d. 

An estimated age at entrainment of sanddab larvae was ca. 6.6 d, based on a growth rate of 0.2 

mm/d and an average length at entrainment of 2.6 mm. Survival to entrainment was estimated as 

0.936 6 = 0.62. 

The FH approach combines larval entrainment losses and adult fecundity to hindcast the numbers 

of adult females effectively removed from the reproductively active population. An estimate of 

mean annual fecundity was 15,414 eggs/female based on a range of fecundity data for females 

measuring 85 to 148 mm in total length (Table 5.2.11-3; Ford 1965). 

Age of maturation was assumed to be equal to 2.5 yr and longevity was assumed to be 6 yr from 

Ford (1965) and Arora (1951). The estimated total larval entrainment was used to estimate the 

TENERA E9-055.0 5-367 Final 316(b) Demonstration 

March 1.2000 
5.2.11 Flatfishes 

number of breeding females needed to produce the number of larvae entrained during the three 

analysis periods. A comparison of Analysis Periods l and 2 show that the value for 1996-97 

(FH = 426; SE = 996) to be greater than the same time period for 1997-98 (FH = 92; 

SE = 215) (Table 5.2.11-4). 

Sensitivity Analysis 

Fecundity had the greatest effect on recalculated values of FH (Table 5.2.11-5). Varying this 

parameter in the model resulted in an FH range of ca. 18-2,210 adult females for Analysis 

Periods 1 and 2, compared to the original estimate of 92-426 adult females. Larval survivorship 

had the next greatest effect on recalculated FH. 

i 

Adult Equivalent Loss (AEL) 

The AEL approach uses estimates ofthe abundance of entrained organisms to project the loss of 

equivalent numbers of adults based on mortality schedules and age at recruitment. Survival rates 

were estimated from entrainment of larval stage to recruitment into the fishery including juvenile 

to 2 yr adults (Table 5.2.11-1). Larval survival was estimated from the average age at 

entrainment through settlement as 

SLarvae = 0.930( 9 °~6 6 ) = 0.002 . 

Survivorship to recruitment was apportioned into several age stages from Ford (1965; Table 

5.2.11-1), and AEL was calculated using the entrainment ofa single age class having an average 

age of 6.6 d. Values of AEL for Analysis Periods 1 and 2 show that the value for 1996-97 

(AEL = 2,370; SE = 6,710) to be greater than the same time period for 1997-98 (AEL = 511; 

SE = 1,450) (Table 5.2.11-6). 

Sensitivity Analysis 

Early larval survivorship had the greatest effect on recalculated values of AEL (Table 5.2.11-7). 

Varying this parameter in the model resulted in an AEL range of 99-12,300 adult equivalents 

among the three analysis periods, compared to the original estimate of 511-2,372 adult 

TENERA E9-055.0 5-368 Final 316(b) Demonstration 

March 1,2000 
P.90 

5.2.11 Flatfishes 

equivalents. Late larval through pre-recruit survivorship had the next greatest effect on AEL. The 

range of entrainment estimates did not substantially change the calculated values of AEL. 

Empirical Transport Model (ETM) 

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

analysis periods ranged from a minimum of zero to a maximum of 0.859±0.9l l (±ISE(PE,)) in 

April 1998 (Table 5.2.11-8). When both PE, and the annual proportion of larvae hatched in the 

/th survey period (fj) were equal to zero, no larvae were collected at either die DCPP intake or 

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

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

For sanddabs, the relatively large PE, for April 1998 resulted from the fact that no sanddab 

larvae were collected in die study grid. This PE, was calculated using the larval density from the 

weekly entrainment sample (Appendix H) multiplied by the unsampled volume inshore ofthe 

two cells nearest the intake (Dl and El) to approximate the number of larvae in this volume. This 

number was then added to the number of larvae found in cells Dl and El, zero in this case as 

well as elsewhere in the grid, to approximate the number of larvae in the whole study grid. The 

accompanying low value of / (0.00893) indicated that there were few sanddab larvae in the 

water column and, therefore, die high PE, had relatively low weight in the annual estimate of 

entrainment mortality. July and August ofthe first study year and May and June ofthe second 

year had higher values of / due to greater larval abundance in the subsamples from these 

months. 

Estimates of PM between years showed the greatest differences in point estimates (Figures 

5.2.1 l-6a and b). Estimated mean and maximum larval durations (7 or 11 d, respectively) were 

relatively similar, causing minimal change in point estimates of PM within-years. Since sanddab 

larvae were dispersed throughout the study grid, Ps was calculated using both onshore and 

alongshore current movements. Density was extrapolated offshore, with a common slope for all 

surveys of 0.0000342/m for Analysis Period 3 and 0.0000661/m for Analysis Period 4. The 

offshore extrapolation of study grid abundance, followed by an alongshore extension, yielded a 

TENERA E9-055.0 5-369 Final 316(b) Demonstration 

March 1,2000 
P.91 

5.2.11 Flatfishes 

range of PM from both analysis periods of 0.4-4.5% ofthe larvae contained in an estimated 

population of approximately 3 to 22 times that in the study grid. The area of extrapolation ranged 

between 3 to 20 times the 52 km-2 area study grid. The extrapolated area was slightly less than the 

population because ofthe slightly increasing trend in density. In comparison, using only 

alongshore extension of study grid abundance, PM ranged from 1-7% ofthe larvae in an area 

two to four times the study grid alongshore or around 30-60 km of coastline distance. 

Interpretation of Assessment Results 

Estimates of adult equivalent loss, both FH and AEL, of sanddabs depend on estimated 

entrainment. Comparisons ofthe annual estimates of FH (92-426) and AEL (511-2,370) from 

Analysis Periods 1 and 2, that have comparable time periods, reflects the effects ofthe high 

entrainment estimates from summer 1997. The estimate of AEL assumes a recruitment age of 2.3 

yr, while females in the fecundity hindcasting estimate range between 2.5 and 6 yr (3.7 yr 

assuming linear survival). The FH and AEL estimates are similar (2-FH 10.25 = 736-3,408) when 

accounting for additional survival (Table 5-2.11-1) and equal number of males as females. 

Sanddabs have both commercial and recreational fishery value. Catch data are available to 

compare harvest mortality rates to entrainment mortality rates. In 1998, an estimated 51,000 

sanddabs were caught by recreational anglers in southern California waters (PSMFC RecFIN 

database). Commercial ex-vessel value in 1998 from ports between San Diego and Mendocino 

totaled $420,100, representing 595.6 MT (PSMFC PacFIN database). Value of sanddab landings 

in the port area of Morro Bay, that includes Port San Luis, in 1998 totaled $7,000, representing 

12.7 MT (PSMFC PacFIN database). 

The estimated larval duration for sanddabs (7-11 d) produced a potential area of effects between 

3-9 times the study area (for 7 d duration) and 9-20 times (for 11 d duration) that was used in 

computing an offshore extrapolation-based Ps (Figure 5.2.11-6). This indicates that only the 

commercial catch from the local ports of Morro Bay and Avila could potentially be affected by 

entrainment. An estimate of 60 g per average adult (Arora 1951) can be applied to the largest 

mortality predicted by the survival-weighted FH estimate. If we assume no compensatory 

TENERA E9-055.0 5-370 Final 316(b) Demonstration 

March 1.2000 
5.2.11 Flatfishes 

Alternately, estimates of annual entrainment mortality (PM ) could be used to determine the effect 

of larval entrainment on Morro Bay area catches. Proportional entrainment mortality ranged from 

-1-7% over areas ranging from 3-22 times the study grid area (larger area associated widi 

smaller mortality). These proportional losses can be applied to die 1993-1999 annual average 

revenue for the Morro Bay area sanddab catch of ca. $8,200/yr (PSMFC PacFIN Database) 

assuming no compensation. This results in an average dollar value impact on die Morro Bay area 

sanddab fishery of $82/yr, by translating a 1% larval mortality to adult losses (using the larger 

extrapolated areas still conservatively less than die fishery area). 

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I 

i mortality and directly apply the ^£Z-based loss to the fishery catch, 3,400 fish represents 0.2 MT 

or $l 10. However, FH and AEL models do not consider selectivity, catchability, and fishing 

effort when extrapolated to fishery losses, so this estimate of monetary value is likely an m 

overestimate ofthe loss to the fishery because it assumes all equivalent adults were harvested. 

Long-term trends, shown by Intake Cove plankton tows (Figure 5.2.11-5), show wide variation 

of larval abundance from 1990-1998 widi no apparent trend. Since the startup of power plant 

operations, sanddabs have increased in Diablo Cove compared to pre-operation observations 

(Figure 4-39 in PG&E 1997c). Fishery harvest information indicates that catches in the MBNMS 

have generally increased between 1980 and 1995 (Starr et al. 1998), but there may be a declining 

trend for catches in the Monro Bay area since 1994 (Figure 5.2.11-7). Declining catches in the 

Morro Bay area could be due to many factors, but without data describing fishing effort it is 

difficult to attribute this apparent decline to any feature ofthe fishery. Since larval abundance • 

does not appear to be declining in the Intake Cove, it seems likely that entrainment mortality is 

not reducing larval production locally or that compensation in birth rates is occurring. 

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5.2.11 Flatfishes 

5.2.11.2 California halibut (Paralichthys californicus) 

Paralichthys californicus (Ayres 1859); California halibut: length to 152 cm; Quillayute 

River, northern Washington to Bahia Magdalena, southern Baja California; nearshore 

to 183 m; eyed side mostly uniform dark brown to black, but often mottled with light 

and dark; blind side usually white (Miller and Lea 1972; Eschmeyer et al. 1983). 

California halibut is an important part of California's commercial and recreational fisheries (Leet 

et al. 1992; Starr et al. 1998). It is generally found on sandy substrata near rocks, kelp holdfasts, 

or other bottom structures (Love 1996). One-year-old individuals can be greater than 80 cm SL 

(Allen et al. 1990). Halibut can live to 30 yr (Frey 1971), with 50% of females mature by 4 yr and 

100% mature by 7 yr (Love and Brooks 1990). They are oviparous, producing planktonic eggs 

and larvae (Oda 1991; Moser 1996) with external fertilization (Allen 1990). Halibut can spawn 

year-round, with peak spawning taking place during the late winter to spring and usually in water 

shallower than 75 m (Lavenberg et al. 1986). Spawning for the fish under natural environmental 

conditions was investigated in the laboratory during three different spawning years (Caddell et al. 

1990; Table 5.2.11-9). They found during their laboratory study that halibut spawned 57 million 

eggs per year in an artificial environmental setting. 

Little information on the population dynamics of larval California halibut was found in the 

scientific literature. In southern California, halibut less than 10 cm SL are found in greater 

numbers in bays than in coastal waters (Plummer et al. 1983). Peak densities of California halibut 

larvae occurred during February in CalCOFI samples (Moser et al. 1993). Moser and Watson 

(1990) found that less than 1% ofthe halibut larvae within the CalCOFI study area were collected 

in the central California zone that extends from just north of Point Conception to just north of San 

Francisco Bay. Allen and Jensen (unpubl. data in Allen et al. 1990) stated that newly settled 

larvae are about 8-12 mm and about 30 d old. Kramer (1990) stated that halibut 6-10 mm larvae 

TENERA E9-055.0 5-372 Final 316(b) Demonstration 

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5.2.11 Flatfishes 

Summary of Field Collections 

Within the DCPP study grid, Califomia halibut larvae occurred sporadically during the two years 

surveyed (Appendix H), with their highest densities occurring during April-May and July 1998 

(Figure 5.2.11-9). No clear distribution pattern was observed in the grid. The density estimates 

from the study grid represented 251 larval California halibut identified from 164 bongo net 

subsamples: 5% ofthe study grid subsamples collected and processed. 

TENERA E9-055.0 5-373 Final 316(b) Demonstration 

March 1,2000 

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I grew <0.3 mm/d, while larger 70-120 mm halibut grew about 1.0 mm/d. In a laboratory study, 

halibut held at 16°C grew to a length of 11.1 mm ± 2.61 (SD) in 2 mo from an initial hatch length 

of 1.9 mm (Gadomski et al. 1990). Instantaneous mortality rates (Z, ) were greatest for the m 

smallest length classes, followed by lower, relatively stable rates for subsequent length classes up 

to 70 mm (Table 5.2.11-10). | 

In the 1985-1988 commercial catch, 63% ofthe California halibut were 6-7 yr (Sunada et al. I 

1990). Fish over 8 yr averaged about 18% ofthe catch, while a few 3 yr fish were large enough 

to be included in the fishery. No stock assessment has yet been published for this species (Bob 

Leos, CDF&G, Monterey, pers. comm.). 

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California halibut larvae were collected seasonally in the DCPP intake entrainment surveys 

during the years 1996-1999 (Appendix H). Halibut larvae at the intake occurred in two periods: 

March-May and July-August (Figure 5.2.11-8). The greatest apparent densities occurred during 

late April 1998. There were 378 California halibut larvae identified from 157 bongo net M 

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

representing 3% ofthe entrainment subsamples collected and processed. I 

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Standard lengths of California halibut larvae collected at the DCPP intake structure ranged from • 

1.5 mm to 8.0 mm (Figure 5.2.11-10). The growth rate of larval California halibut (0.28 mm/d) 

reported by Allen et al. (1990) was used to estimate ages of entrained larvae. The central 98% of • 

this larval length-frequency distribution resulted in minimum and maximum lengths for the 

analyses of 1.6 mm and 7.8 mm, respectively. The mean larval length in this distribution was • 

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5.2.11 Flatfishes 

3.28 mm and approximately 6 d post-hatch. Reported hatching size for California halibut ranges 

l .5-1.8 mm (Moser 1996,) and it is one ofthe smaller larvae entrained at DCPP. The collection 

of just a few California halibut larvae from the paired entrainment and study grid surveys 

precluded statistical comparisons of larval length (Figure 5.2.11-11). 

Estimating Total Annual Entrainment 

Annual estimated entrainment of California halibut larvae was greater in 1997-98 Analysis 

Period 2 (E- = 14,300,000; SE = 2,130,000) than in 1996-97 Analysis Period 1 

(E^ = 2,270,000; SE = 296,000) (Table 5.2.11-11). These estimates represent a total of only 378 

individual larval California halibut collected at the DCPP intake structure. Although the number 

of larval California halibut entrained was low it was chosen for assessment because ofits 

importance in sport and commercial fisheries. 

Estimated annual entrainment of California halibut larvae was adjusted (Table 5.2.11-12) to the 

long-term average index (7 //,) estimated from Intake Cove surface plankton tows (Figure 

5.2.11-12). The index was calculated as the ratio between the nine year average (J ) of Intake 

Cove sampling and the average annual index estimated from the plankton tows during the year 

being adjusted (I,). The average indices for the years 1997 and 1998 (I,) were 0.0005 and 

0.0016 larvae/m^, respectively. The long-term average index (7 ) was 0.0017 larvae/m^ for the 

years 1990-1998, yielding the ratio 7/7, of 3.64 for 1997 and 1.10 for 1998 indicating that 

Intake Cove density in these years was lower than the long-term average. Annual adjusted 

entrainment of California halibut larvae was estimated to be 8,260,000 in 1996-97 Analysis 

Period 1 (SE = 1,080,000) and 15,700,000 in 1997-98 Analysis Period 2 (SE = 2,340,000) 

(Table 5.2.11-12). 

NOTE: Annual entrainment estimates of California halibut larvae were not used to estimate FH 

or AEL because no larval survival data were available to parameterize these models. However, an 

approximate FH estimate is made in the interpretation section below. 

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5.2.11 Flatfishes 

Empirical Transport Model (ETM) 

Monthly estimates of proportional entrainment (PE,) for California halibut in each rth survey 

from the two years sampled ranged from a minimum of zero to a maximum of 0.859±0.9l l 

(±\SE(PE,)J ) in April 1999 (Table 5.2.11-13). During periods when no larvae were collected at 

either the DCPP intake or from the study grid, both the annual proportion of larvae hatched in the 

rth survey period (f) and PE, were equal to zero. When PE, = 0 but f>0, larvae were 

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

paired with the 72-hour study grid survey. The maximum PE,, recorded in April 1999, was the 

result of using study grid estimates based only on inshore volumes as no larvae were found in 

study grid cells. That is, PE for this survey period was calculated using the larval density from 

die weekly entrainment sample (Appendix H) multiplied by the unsampled volume inshore of 

the two cells nearest the intake (Dl and El) to approximate the number of larvae within this 

volume. The product was added to the abundance in cells Dl and El, zero in this case as well as 

elsewhere in the grid, to approximate the number of larvae in the whole study grid. The low value 

of / during April 1999 indicated that California halibut were not as prevalent as they were 

during August 1998 or March 1999. In comparison with PE, a month earlier, their distribution 

was more inshore during April 1999. 

Estimates of PM showed greater differences between years than between larval durations during 

the same year (Figures 5.2.11-13). Since halibut larvae were dispersed throughout the study grid, 

Ps was calculated using both onshore and alongshore current movements with a common slope 

used for offshore extrapolation of study grid abundance of 0.0000252/m for Analysis Period 3 

and 0.0000127/m for Analysis Period 4. Using offshore extrapolation of study grid abundance 

pattern followed by alongshore extension yielded a range of PM from both analysis periods of 

0.07-0.08% (1997-1998) and 5-12% (1998-1999) ofthe larvae contained in a population area 

approximately 4 to 39 times the study grid area (and 4 to 35 times the grid's estimated larval 

population size). In comparison, PM results using only alongshore extension of study grid 

abundance also reflected differences between the years' results, ranging from 0.3-25% ofthe 

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5.2.11 Flatfishes 

larvae in an area two to six times the study grid alongshore or around 41-105 km of coastline 

distance. 

Interpretation of Assessment Results 

California halibut have both commercial and recreational fishery value. Commercial vessel 

landing prices in 1998 from ports between San Diego and Mendocino totaled $2,746,700 

representing 532.1 MT (PSMFC PacFIN database). During the same year, landings in the Morro 

Bay area totaled about 10% ofthe catch from this larger area (54.8 MT and $264,000; PSMFC 

PacFIN database). In 1998, recreational fishers in southern California caught 66,000 adult 

California halibut (PSMFC RecFIN database). 

The estimated age of larval California halibut entrained at DCPP averaged six days with a 

maximum estimated age of 22 d. The average duration, combined with current meter data, 

produced an extrapolated reference population that ranged from 4-8 times the study area between 

sampling years, while the maximum duration produced a reference population contained in an 

area 23-39 times the study grid. The population contained within the study grid and extended 

alongshore using current meter data and both average and maximum larval age at entrainment 

ranged over shoreline distances of 10-170 km. Therefore, we assumed that the commercial catch 

likely affected by entrainment was limited to the local ports of Morro Bay and^Port San Luis. 

Estimates of stock size or adult density that could be used to convert PM numbers of adult fishes 

were not available for this species. However, proportional losses predicted by ETM can be 

applied to the 1993-1999 average value ofthe local catch of $161,000/yr (PSMFC PacFIN 

Database) assuming no compensation. Thus, the proportional dollar loss to this fishery in the 

Morro Bay area could range from ca. $120-20,000 based on PM ranging from 0.00076-0.123 

from the combined offshore extrapolated and alongshore extension ofthe study grid abundance. 

Between-year differences in larval California halibut density at DCPP could be the result of 

changes in nearshore, coastal transport processes or may reflect some other factors. Relatively 

higher abundance observed in the study grid during the 1997-98 El Niiio event may have been 

TENERA E9-055.0 5-376 Final 316(b) Demonstration 

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5.2.11 Flatfishes I 

due to increased shoreward transport at DCPP (out ofthe south) or could be related to suppressed m 

upwelling during that period. However, the nine years of Intake Cove plankton tow data indicate 

that larval California halibut density does not vary greatly from the long-term average with the *• 

exception ofa single strong year-class in 1992. Additionally, catches in the MBNMS appear to 

be relatively stable or only slightly decreasing between 1980 and 1995 (Starr et al. 1998); local 

Morro Bay area catches show a similarly stable catch between 1993 and 1999 (Figure 5.2.11-

14). One explanation for the apparent between-year differences of entrainment effects is high 

interannual variability within the study period due to low sample size: only 378 California halibut 

larvae were collected over the course ofthe study. The large 1998-99 estimated larval mortality 

is based on a limited number of California halibut larvae. 

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TENERA E9-055.0 5-377 Final 316(b) Demonstration ' 

March 1,2000 I 

Using the adjusted entrainment estimated over 1996-97, an estimate of FH can be made 

assuming a relatively small larval survival of 0.5/d during six days, average yearly fecundity of 

4.9 million eggs (Table 5-2.11-9), and reproductive life of 11.5 yr as 

£T> pAdj-T 8.3x1 Q6 

FH = „ A.= -. r-= 9 females 

An estimate similarly can be made for 1997-98 as 18 females. These small adult female losses 

indicate that while PM is large for 1998-99, die population impact is probably slight. 
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5.2.11 Flatfishes 

Table 5.2.11-1. Life table for speckled sanddab (C. stigmaeus) covering the probable 

lifespan, where x is the age in months, bx the number of eggs spawned per female within 

the interval and lx the number surviving at the start ofthe interval. Separate lx columns are 

given for the 1962-63 and 1963-64 survival data. Values of Zx for age group 3 were 

estimated by assuming the same mortality rate for age 2 and 3 fish. Intrinsic rate of natural 

increase, intrinsic birth and mortality rate, and generation length, based on these data, are 

given for 1962-63 and 1963-64 (Table 25 in Ford 1965). 

Life stage/Age 

(yrs) 

Eggs and larvae 

0 

1 

2 

3 

Age 

j (mo) 

0-3 

3-6 

6-9 

9-12 

12-15 

15-18 

18-21 

21-24 

24-27 

27-30 

30-33 

33-36 

36-39 

39^12 

42-45 

bx 

0 

0 

0 

0 

3,500 

700 

0 

0 

1,010 

2,000 

0 

0 

1,860 

3,700 

0 

1962-63 

lx 

100,000 

150 

82 

45 

44 

42 

41 

40 

33 

27 

22 

18 

14 

12 

10 

1963-64 

Zx 

100,000 

150 

87 

51 

38 

29 

22 

16 

12 

8 

6 

4 

3 

2 

1 

Survival 

0.00150 

0.563 

0.567 

0.861 

0.859 

0.867 

0.851 

0.788 

0.742 

0.782 

0.742 

0*764 

0.762 

0.667 

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5.2.11 Flatfishes 

Table 5.2.11-2. Estimated total annual entrainment (ET ) and standard error 

(SE(Er)) for sanddab (Citharichthys spp.) larvae from the three analysis 

periods. 

Analysis Period Ej SE(E,) 

1) Oct 23, 1996-Sep 30, 1997 7,160,000 702,000 

2) Oct. 1,1997-Sep 30, 1998 1,540,000 283,000 

3) Jul 1, 1997-Jun 30, 1998 6,610,000 704,000 

Table 5.2.11-3. Estimated number of eggs spawned per season by 

speckled sanddabs (Citharichthys stigmaeus) collected during 

April and May 1963 (Ford 1965) 

Total length 

85.0 

90.5 

109.5 

110.5 

129.0 

130.0 

148.0 

Total # mature and 

maturing eggs 

4,300 

4,100 

15,200 

9,000 

20,900 

23,600 

30,800 

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