';c.O Cajundome 80Llltvard

Lafayette. La. 70506

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Nattonal Wetlands Research Center

IJ. S. Fish and ",HdUfe Service

BIOLOGICAL REPORT 82(10.153)

MARCH 1988

HABITAT SUITABILITY INDEX MODELS:

RED KING CRAB

and Wildlife Service

SK

361

. U54

n o . 82-

10 .1 53

Department of the Interior
MODEL EVALUATION FO~'

Habitat models are designed for a wide variety of planning applications

where habitat information is an important consideration in the decision

process. It is impossible. however. to develop a model that performs equally

well in all situations. Each model is published individually to facilitate

updating and reprinting as new information becomes available. Assistance from

users and researchers is an important part of the model improvement process.

Please complete this form following appl ication or review of the model. Feel

free to include additional infonnation that may be of use to either a model

developer or model user. We also would appreciate information on model

testing. modification. and application. as well as copies of modified models

or test results. Please return this fonn to the following address.

National Wetlands Research Center

U.S. Fish and Wildlife Service

1010 Gause Boulevard

Slidell. LA 70458

Thank you for your assistance.

Species _ Geograph ic

Location"---------------------------------------

Habitat or Cover Type(s) _

Type of Application: Impact Analysis Management Action Analysis _

Baseline Other------------------------------------------------- Variables Measured or Evaluated----------------------------------------

Was the species infonnation useful and accurate? Yes No

If not. what corrections or improvements are needed?-----------
Were the variables and curves clearly defined and useful? Yes No

If not, how were or could they be improved? __

Were the techniques suggested for collection of field data:

Appropriate? Yes No

Clearly defined? Yes No

Easily applied? Yes No

If not, what other data collection techniques are needed?

Were the model equations logical? Yes No

Appropriate? Yes No

How were or could they be improved?

Other suggestions for modification or improvement (attach curves,

equations, graphs, or other appropriate information) _

Additional references or information that should be included in the model:

Model Evaluator or Reviewer Date ---------------------- -------------

Agency _

Address -----------------------------------------------------------

Telephone Number Comm : FTS _
Biological Report 82(10.153)

March 1988

HABITAT SUITABILITY INDEX MODELS: RED KING CRAB

by

Stephen C. Jewett

Alaska Cooperative Fishery Research Unit

138 Arctic Health Research Building

University of Alaska

Fairbanks, AK 99775

and

Christopher P. Onuf

U.S. Fish and Wildlife Service

National Wetlands Research Center

1010 Gause Boulevard

Slidell. LA 70458

Performed for

U.S. Department of the Interior

Fish and Wildlife Service

Research and Development

National Wetlands Research Center

Washington. DC 20240
This report should be cited as:

Jewett, S.C., and C.P. Onuf. 1988. Habitat suitability index models: red

king crab. U.S. Fish Wi1d1. Servo Bio1. Rep. 82(10.153). 34 pp.
PREFACE

This document is part of the habitat suitability index (HSI) model series

and is designed for use with the U.S. Fish and Wildlife Service's (1980)

habitat evaluation procedures in impact assessment and habitat management

activities. The model was developed from a review and synthesis of existing

information. It is not intended to be an exhaustive literature review. It is

scaled to produce an index of habitat suitability between 0 (unsuitable

habitat) and 1 (optimally suitable habitat). Model documentation and

guidelines for model applications, including methods for measuring model

variables, are provided.

Model documentation is provided for several reasons. First, it provides a

means of explaining the model's structure and its inherent assumptions.

Second, the model-building process involves considerable judgement on the part

of the model builder, and documentation provides the insights necessary to

modify the model when these judgements are inconsistent with local or new

knowledge. Finally, the documentation should facilitate modification of the

model to meet individual study constraints on time and human resources.

The model presented is a hypothesis of species-habitat relationships, not

a statement of proven cause and effect. For this reason, users of the model

are encouraged to suggest improvements that may increase the utility and

effectiveness of this habitat-based approach to fish and wildlife management.

Please send suggestions to the following address:

Information Transfer Specialist

National Wetlands Research Center

U.S. Fish and Wildlife Service

1010 Gause Boulevard

Slidell, LA 70458.

iii

CONTENTS

PREFACE . TABLES •••••••••••••

ACKNOWLEDGMENTS .•• . .

iii

vi

vii

1

1

2

7

7

8

9

11

12

14

14

15

17

22

23

24

for Model Variables •••••• Determination•••

. .

Applicability .

Salinity .

Ternperat ure . HABITAT SUITABILITY INDEX (HSI) MODEL •••..••••••..••••••••.

Model

Model Description .........................•..•..•.•••...

Suitability Index (SI) Graphs

Component Index (CI) Equations and HSI

Field Use of the Models ••............•.••••••....••••.••.•••..

Interpreting Model Outputs ..•..•......•••••••....••••....••.....•.

INTRODUCTION .••••••••••

Distribution •.•........••••••••••

Life History Overview ••.••••••.

SPECIFIC HABITAT REqUIREMENTS •••..•..

Substrate .

Vegetation .

Food .•..•..•.

REFERENCES •••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 27

v
TABLES

Number

1

2

Fecundity of red king crab from various areas •••••••••.•••

Size at maturity of red king crab from various areas••••••

3

4

3 Size at 50% maturity of female red king crab from various

areas. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

4

5

Domi nant prey of red king crab from three shallow

locations around Kodiak Island •••.••••••••••••••••••••••••

~at~ sources and assumptions for red ki ng crab suitabil ity

tnd ices •••••••••••••••••••••••••••••••••••••••••••••••••••

10

21

6 Calculation of suitability indices, component indices, and

habitat suitability indices for three hypothetical study

areas. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

7 Suggested techniques for obtaining the data necessary to

app1y the red king cr ab HS I models ••••••••••••••••••••••••

vi

25
ACKNOWLEDGMENTS

The authors wish to thank Robert Otto and Bradley Stevens, National

Marine Fisheries Service, Northwest and Alaska Fisheries Center, Kodiak,

Alaska; A.J. Paul, University of Alaska, Institute of Marine Science, Seward;

and Daniel Wickham, University of California, Bodega Marine Laboratories,

Bodega Bay, for valuable comments on an earlier draft of this report.

Evaluation of model structure and functional relationships was provided by personnel of the U.S. Fish and Wildlife Service's (FWS) National Wetlands

Research Center and of the FWS Division of Ecological Services in Fairbanks

and Juneau, Alaska. Funding was provided by U.S. Fish and Wildlife Service.

vi i
RED KING CRAB (Paralithodes camtschatica)

INTRODUCTION

The red king crab (Paralithodes camtschatica) belongs to the family Lithodidae and is one of three commercially exploited king crabs in the

eastern North Pacific Ocean. Until recently this crab was the most valuable

shellfish resource on Alaska's Continental Shelf. In the 1980-81 fishing

season domestic fishermen harvested a record 81.6 thousand metric tons (t),

which had an ex-vessel value of nearly $180 million. Landings plummeted annually thereafter to only 2.6 thousand t in 1985-86. In that season

fishermen received only $14.8 million, even though the price per weight nearly

tripled from 1980 to 1986 (Alaska Department of Fish and Game 1985a,b,c,d,

1986). Exact causes underlying the drastic decline of this species are

unknown, although a combination of high natural mortality and variable yearclass strength probably is involved (Otto 1986). Inadequate management

practices are not blamed (Otto 1986). Possible causes for natural mortality

are predation by Pacific cod (Gadus macrocephalus), Pacific halibut

(Hippoglossus stenolepis), and yellowfin sole (Limanda aspera) on larval

through adult life stages and by nemertean worms (Carcinonemertes spp.) on

eggs (Armstrong 1983; Haflinger and McRoy 1983; Hayes 1983; Wickham et ale

1985; Blau 1986) and viral and microsporidan diseases (Sparks and Morado 1985)

(see Fukuhara 1985 for a review on predation).

Distribution

The red king crab occurs on both sides of the North Pacific Ocean at

depths <400 m. It is found from the Sea of Japan northward into the Sea of

Okhotsk and along the shores of the Kamchatka Peninsula; the northern limit on

the Asiatic coast is at Cape Olyutorskiy (60 ON latitude) (Vinogradov 1947).

On the western coast of North America, the northern limit is Point Barrow,

Alaska (71025 1 N latitude) (MacGinitie 1955). The species occurs throughout

the southeastern Bering Sea, the Aleutian Islands, and the Gulf of Alaska to

the southern limit off the Queen Charlotte Islands, British Columbia (54 ON

latitude) (Butler and Hart 1962). A population of introduced red king crab

also exists in the Barents Sea (Orlov and Ivanov 1978).

Historic major domestic fishery locations are Norton Sound in the

northeast Bering Sea, the southeast Bering Sea, the Aleutian Islands, south of

the Alaska Peninsula, near Kodiak Island, and Cook Inlet, while Prince William

Sound and southeast Alaska support smaller fisheries (Alaska Department of

Fish and Game 1985a,b,c,d). Major historic foreign fishing locations are on

the west coast of the Kamchatka Peninsula, along Hokkaido and Sakhalin, and on

the Japan Sea coast of the U.S.S.R. (Marukawa 1933; Vinogradov 1947). The

commercial fishery is generally confined to depths <200 m. Adult king crab

1
and those close to maturity use the deeper, offshore waters during most of the

year; shallower waters «50 m) are typically used during mating in the spring

(Powell and Nickerson 1965a). Some deeper offshore areas (50-100 m) are also

used for mating (McMullen 1967); however, the extent of offshore breeding is

not known. Juveniles <4 years old (approximately 70-mm carapace length - CL)

typically occur in depths <50 m (Powell and Nickerson 1965b; Sundberg and

Clausen 1977; McMurray et al. 1984).

Life History Overview

Reproduction. Male red king crab are polygamous. Under confined

conditions a male will mate with up to seven females annually (Powell et al.

1974). Under natural conditions the number of females mated by one male is

unknown, although the sex ratio during the mating period suggests that one

male may service as many as 11 females (McMullen 1967). The adult male to

female ratio on the spawning grounds of outer Alitak Bay was 1:2 in May 1962

(Gray and Powell 1966) and 1:7 in March 1977 (Feder and Jewett 1977). Females

mate annually with only one male (Powell and Nickerson 1965a). Adult males

are typically larger than their female partners (Powell et al. 1973, 1974);

however, no relationship between size of partners has been established.

Reproductive activities (egg-hatching, female-molting, mating, and spawning)

have been observed in shallow waters «20 m) near Kodiak Island from January

through June, but most activity is during March through May, specifically

April (G. Powell, Alaska Department of Fish and Game [retired], Kodiak, pers.

comm.; S. Jewett, pers. observ.). After egg hatching is nearly complete, each

female is thought to chemically attract a male mate as lobsters do (Hughes and

Mattiessen 1962). The male crab faces and grasps the female with his chelae at

the base of her first appendage. This precopulatory embrace lasts anywhere

from one to 16 days until the female molts (Powell et al. 1974). After the

female molts, the male releases the cast shell, reclasps her, and spreads

spermatophore bands (sperm) around her gonopores (genital openings). The male

then releases her and she lays her eggs, depositing them externally on her

abdomen. The eggs are fertilized externally as they emerge from the gonopores

(Powell and Nickerson 1965a). Egg attachment to the abdominal pleopods occurs

immediately upon extrusion (McMullen 1970).

Adult female red king crab typically produce a full clutch of eggs each

year. The percentage of adult females carrying eggs near Kodiak Island in the

fall of 1968 was 86.4%, with a range from 28% to 100% for different areas

around the island (McMullen and Yoshihara 1969). Ovigerity among adult

females in the southeastern Bering Sea was also examined for the years 1975-79

(Otto et al. 1980). The percentage of ovigerous females having a full clutch

of eggs (defined as three-fourths full to full) exceeded 90 percent in four of

five years, suggesting that clutch size was a stable population parameter.

Fecundity, measured within a few months after deposition, varies from

15,000 to nearly 447,000, depending on the area (Table 1). Incubation lasts

11 to 12 months before hatching begins (Haynes 1968).

Life stages. Red king crab pass through two distinct stages: a short

pelagic stage and a long benthic stage. Upon hatching, the pre-zoeal larvae

molt, usually within minutes, into the zoeal form (Weber 1967). The pelagic

2
Table 1. Fecundity of red king crab from various areas.

Area No. of eggs

Carapace

length, mm Source

Hokkaido

Hokkaido

Hokkaido

S. Alaska Peninsula

Bristol Bay

Cook Inlet

62,500-345,900

69,600-270,200

15,300-214,400

148,300-446,600

55,400-444,700

30,000-390,000

1I8-158a

106-157a

97-144a

128-145

85-162a

100-170

Nakazawa (1912)

Murukawa (1933)

Sato (958)

Wallace et al. (1949)

Rodin (970)

Haynes (1968)

aConverted from carapace width after Wallace et al. (1949)

zoeae larvae molt through four stages, each lasting 2-4 weeks. A fifth larval

stage is the semipelagic glaucothoe which lasts 3-4 weeks. The metamorphosis

to first postlarval instar occurs 3-4.5 months after hatching (Marukawa 1933;

Kurata 1960, 1961a,b; Weber 1967; Armstrong et al. 1981). Time of hatch

within a region is not necessarily synchronous and multistage larval

populations often occur simultaneously (Armstrong et ale 1981). Interannual

timing of the onset of hatch and seasonal occurrence of pelagic larvae can

vary by as much as 4-6 weeks (Armstrong et al. 1981; McMurray et ale 1984). A

large interannual difference in apparent time of hatch in the southeastern

Bering Sea was observed between the years 1976 and 1979. All larvae were

Stage I zoeae in mid-May 1976, but all were Stage IV in mid-June 1979,

indicating a very late and early hatch, respectively (Armstrong et ale 1981).

This variability is presumably due, in part, to environmental conditions

(mainly temperature) and timing of breeding among primiparous vs. multiparous

females (Powell et al. 1973; Incze et ale 1986; Stevens and MacIntosh 1986).

Larval densities in the southeastern Bering Sea are highest over bottom depths

of 40-70 m, extending 20-50 km offshore along the Alaska Peninsula (Armstrong

et ale 1981).

The benthic life stage may last 15 (McCaughran and Powell 1977) to 20

years (Kurata 1961b). By this age, crab are approximatey 220 mm CL and weigh

approximately 10 kg (Wallace et al. 1949).

Growth. During pelagic development, growth of larvae is substantial,

with increases from 0.2-0.3 mg dry weight as Stage I zoeae to >1.2 mg as

glaucothoe (Armstrong et al. 1981). After settlement crab molt from 8 (Powell

1967) to 11 (Weber 1967) times in the first year. Between the end of the first

year and the end of the third year, an additional eight molts occur;

thereafter, typically only one molt a year occurs (Weber and Miyahara 1962;

Weber 1967). Juveniles in the Kodiak Island vicinity and the southeastern

Bering Sea reach about 11, 35, 60, and 80 mm CL at 1, 2, 3, and 4 years,

respectively (Powell and Nickerson 1965b; Weber 1967; also see Incze et ale

1986 for size classes up to Age 6).

Red king crab are sexually mature at 5 to 6 years old or, depending on

the area, between 60 and 112 mm CL (Tables 2 and 3). Maturity of males and

females within an area is often attained at similar sizes. Based upon growth

3
Table 2. Size at maturity of red king crab from various areas.

Area

Kodiak Island

Pacific Ocean

Sea of Nemuro

S.E. Bering Sea

S.E. Bering Sea

S.E. Bering Sea

Kamchatka Coast

W. Kamchatka

Norton Sound

Norton Sound

Carapace

length, mm

100a

93-1l2 b

92- 96 a .c

85-102a

90-105a

b 76-105

78- 82a

87- 92 b

60- 79 b

62- 82b

Source

Powell and Nickerson (1965a)

Wall ace et a1. (1949)

Marukawa (1933)

Wallace et al. (1949)

Weber (1967)

Otto et al. (1980)

Marukawa (1933)

Matsuura et al. (1972)

Powell et al. (1983)

Stevens and MacIntosh (1986)

aBoth sexes.

bFemales only.

cConverted from carapace width after Wallace et al. (1949).

Table 3. Size at 50% maturity of female red king crab from various areas.

Area

Pacific Ocean

S.E. Bering Sea

S.E. Bering Sea

S.E. Bering Sea

W. Kamchatka

Norton Sound

Norton Sound

Carapace

length, mm

106

97

90- 97

86- 90

80a

68

73

Source

Wallace et al. (1949)

Wallace et al. (1949)

Weber (1967)

Otto et al . (1980)

Matsuura et al. (1972)

Powell et a1. (1983)

Stevens and MacIntosh (1986)

aConverted from carapace width after Wallace et al. (1949).

data obtained through tagging studies, the mean annual growth of adult male

king crab near Kodiak Island (Powell 1967) and the southeastern Bering Sea

(Weber and Miyahara 1962) is 20 and 16 mm CL, respectively. Simpson and

Shippen (1968), however, maintained that since many of the larger crab do not

molt annually, an average annual growth of 10 mm is more realistic for

describing annual growth for the adult male population in the southeastern

Bering Sea. Average annual growth for legal males in Norton Sound is 12.5 mm

CL (Powell et al. 1983). Commercial size limits for the male-only fishery are

set to ensure that males have two opportunities to mate before entering the

fishery (Otto 1985). This measure serves to protect the reproductive

potential of the population. Size at maturity within an area can be variable

from year to year, presumably due to different environmental conditions. In

the southeastern Bering Sea, Weber (1967) observed a change in the size at

which 50% of females were mature from about 90 to 97 mm CL over 4 years. Otto

et al. (1980) observed this value to vary from 86 to 90 mm CL over 5 years.

4
Growth models for the species have been developed by Weber and Miyahara

(1962), Weber (1967), Balsiger (1974), McCaughran and Powell (1977), and

Reeves and Marasco (1980). Growth data are also presented in Kurata (1961a,b)

and Hayes and Montgomery (1963).

Mortality. Egg loss is closely related to the age of the eggs, trends in

egg growth, structural changes in the embryo (Matsuura and Takeshita 1985),

and egg predation (Wickham et ale 1985). Among laboratory-reared king crab,

egg loss during incubation is reported to be 13%-24% in multiparous females

(three individuals) and nearly 50% in a single primiparous female (Matsuura

and Takeshita 1985). Matsuura and Takeshita (1985) noted that egg loss was

greatest at the beginning of the incubation period, presumably due to

unsuccessful egg attachment to the pleopods. Cumulative egg loss in a

primiparous individual after 1 day, 5 days, and 3.5 months of incubation was

8%, 9%-20% and 50%, respectively. Egg loss appeared to decrease near the

middle of the incubation period.

Egg mortality has recently been traced to predation by nemertean worms

(Carcinonemertes). The number of nemerteans found in certain populations in

the Gulf of Alaska represent the most massive infestation ever observed on any

crab species (Wickham et ale 1985). Sample collections of red king crab were

found with average densities up to 199 worms per 1,000 crab eggs; populations

on individual crab reached over 250,000. Many populations have measured egg

mortalities in excess of 90%. Populations from Cook Inlet lost their entire

reproductive output by September, slightly more than halfway through their 11-

month brooding period (Wickham et al. 1985). An annual survey by the Alaska

Department of Fish and Game in September 1983 near Kodiak Island revealed that

all adult females caught (n=341) were barren, having only empty egg cases

attached to the pleopods (Blau 1986). This marked the first time in the 30

year history of Kodiak king crab research that a population of females around

the island was found totally barren. Carcinonemertes was the major suspect for

egg loss, but this was not corroborated.

Typically, at least 90% of the adult females carry a full clutch of eggs

(see Reproduction section). However, in recent years the percentage of barren

females may have increased in some areas (R. Otto, Northwest and Alaska

Fisheries Center, Kodiak, AK; pers. comm.).

Cycles of abundance suggest that year-class success may depend on

survival at a critical life stage such as the eggs, larvae, or young

juveniles. However, the factors responsible for success are often unknown.

The large year-classes of 1971 and 1978 in the southeastern Bering Sea were

produced by two opposite extremes of adult female abundance (Incze et ale

1986). The large juvenile population observed during the middle 1970 ls led to

abundant ,stocks of adults during the late 1970 1s. In contrast, the large

year-class identified during 1982 did not show up in 1983, 1984, or 1985

(Incze et al. 1986). Year-class success is presumably related to water

temperature. Long-term series temperature data are not available for the

southeastern Bering Sea; however, such a series is available for the Gulf of

Alaska (Royer 1985). During the 1971-84 period the water column temperature

increased an average of 1.5 °C along the coast of the Gulf of Alaska

(monitored at 59°50.8 1 N, 149°28 1 W) (Royer 1985).

5
The act of molting is physiologically stressing, and the high frequency

of molting in the first few years could elevate mortality (Rice et al. 1985).

Factors influencing molting rate, such as temperature, might therefore be

responsible for some differences in year-class strength.

Instantaneous mortality rates of older juvenile and sublegal, sexually

mature red king crab have been estimated to be low, about 10% per year until

entering the fishery (Balsiger 1974; Reeves and Marasco 1980). Natural

mortality for adult males (>135 mm CL) in the absence of a fishery generally

increases with size to as high as 25% for crab of 170 mm CL (Hirschhorn 1966).

Increased rates of natural mortality were undoubtedly the major cause of the

recent recruitment failures in the southeastern Berinq Sea, because the size

limit and harvest quota on the fishery assured an adequate reproductive stock

(Otto 1986).

Although one of the major mechanisms contributing to na~ural mortality is

suspected to be predation, little specific information 1S available. An

estimate of the magnitude of predation on larval red king crab is available in

Haflinger and McRoy (1983). They conservatively estimated that 1.8 x 101 0 king

crab glaucothoe larvae were consumed by yellowfin sole in the southeastern

Bering Sea in a one-month period. This consumption value may not be

significant when one considers the number of glaucothoe that may have been

available. The estimated number of adult females in the southeastern Bering

Sea in 1982 was 5.48 x 107 (Incze et al. 1986). If one assumes that 90% of

these adults had full clutches of 1 x lOs eggs and 75% hatched, then

approximately 3.7 x 101 2 larvae hatched. Assuming 10% of the larvae reached

the glaucothoe stage, 3.7 x lOll were available. Yellowfin sole consumed

1.8 x 101 0 or only 5% of the available larvae.

Shimida and June (1982) sampled Pacific cod extensively throughout the

eastern Bering Sea and found that over 10% of the cod stomachs examined in

1981 contained newly molted red king crab. Apparently cod do not prey on king

crab except during molting, since studies conducted during other seasons have

found few king crab in the cod stomachs (S. Jewett, pers. observ.).

Thousands of demersal fish stomachs were examined from the Gulf of Alaska

and Bering Sea during 1975-1980, and king crab were rarely found as prey

(Feder and Jewett 1981a). Other predators on king crab include Pacific

halibut, sculpins (Hemilepidotus and Myoxocephalus) , Korean hair crab

(Erimacrus isenbeckii), and sea otters (Enhydra lutris). However, the extent

of predation is not known.

Movement. Sampling of larval red king crab in the spring in the

southeastern Bering Sea showed strong evidence of diel vertical migration

(McMurray et al. 1984). The noon and midnight samples exhibited the greatest

difference in vertical distribution, with higher densities at noonday at 40 m

and at midnight at 10 m. This trend was not as apparent in two bays of Kodiak

Island (Wolotira et al. 1984). During the day, most larvae were found 5-20 m

below the surface in Kiliuda Bay and in the upper 60 m of the water column in

Izhut Bay. Relatively few remained at or near the surface at night in both

bays; most were at 40-100 m.

6
Based on data on development time (3-4.5 months) and current speeds in

the southeastern Bering Sea, larvae could be transported over 200 km from

hatch to metamorphosis (Armstrong et al. 1981). Since optimal bottom type

does not occur uniformly along the North Aleutian Shelf into Bristol Bay, the

location of spawning females and the dispersion of larvae by oceanographic

factors (e.g., current speed and direction) are the major determinants of

placement of larvae over optimal benthos at metamorphosis (Armstrong et al.

1981). This rationale also applies throughout the range of the red king crab.

When king crab are about 1 year old, they emerge from rock crevices, kelp

patches, and other protective niches where they have been living since

settling as glaucothoe larvae a year before (Jewett and Powell 1981). They

gather with crab of similar size, and one small group meets another forming

larger groups. As these groups join, mounds of crab or pods are formed,

sometimes consisting of thousands of individuals. Juvenile crab in the 2+ to

3+ age classes are known to pod frequently throughout the year in the shallow

water «50 m). Most podding crab are smaller than 69 mm CL (Powell and

Nickerson 1965b). Vinogradov (1969) reported that the maximum size of

nonmigrating crab is about 65 mm CL (converted from 70-mm carapace width after

Wallace et al. 1949).

At approximately 4 years old, king crab begin their onshore-offshore

migration with the adults. The adults migrate to shallow waters generally

during spring months, and then gradually return to deeper water. Tagging

studies have revealed little about within-year movement. However, based on

release and recovery data, migrations typically do not exceed 61 km in the

Norton Sound crab stock (Powell et ale 1983), 185 km in the southeast Bering

Sea stock (Simpson and Shippen 1968), and 65 km in the south Alaska Peninsula

stock (Hayes and Montgomery 1963). The longest distance traveled by a crab

during a single year was 426 km (Simpson and Shippen 1968). Sexes of the

adults and subadults (usually refers to individuals that will reach maturity

on the next molt) are normally segregated in deep water, but occur together in

shallow water or in offshore breeding areas (Powell and Nickerson 1965a;

McMullen 1967).

SPECIFIC HABITAT REQUIREMENTS

Substrate

The distribution of young-of-the-year red king crab is generally

restricted to coarse substrates such as boulders, gravel, cobble, and shell

debris with attached epifauna (Powell and Nickerson 1965b; Tsalkina 1969;

Sundberg and Clausen 1977; McMurray et ale 1984). Dependence upon such a

refuge substrate appears to progressively diminish for crab from Age 1 to Age

4. One area along the west Kamchatka Shelf that is especially important for

young-of-the-year crab is the Cape Khairyuzovo coastline (57°061 Nand 156°341

E) (Tsalkina 1969). Rocky bottoms predominate there, resulting in abundant

sessile epifauna. Young crab in this area live mainly among an assemblage of

hydroids (28 species), sponges (24 species), and bryozoans (10 species). Twoyear-old crab were generally caught at locations where the epifauna was

considerably sparser. The depth of the area surveyed was 1.5 to 20 m.

7
Statistical analyses indicate that juvenile crab distributions correlate

better with biological parameters than physical parameters (McMurray et ale

1984). In the Bristol Bay region of the southeastern Bering Sea (mainly <50

m), strong, positive correlations were found between young-of-the-year cra~

and tube-building polychaete worm biomass and between juvenile crab through

Age 2 and sea urchin (Strongylocentrotus droebachiensis) biomass. Older

juvenile crab distributions correlated positively with tunicate (Boltenia

ovifera) biomass (McMurray et ale 1984).

In Cook Inlet, an embayment of the northern Gulf of Alaska «27 m),

young-of-the-year crab were mainly found among coarse substrates (phi values

<-3) containing dense refuge habitats of bryozoans (Flustrella sp. and

Dendrobenia spp.), hydroids, sponges, and filamentous red algae (Sundberg and

Clausen 1977). At five locations where postlarval crab were found, densities

of 1.3/m2 were observed (Sundberg and Clausen 1977).

Young crab depend on an environment which provides for adequate food (i.e., hydroids and bryozoans) and protection from predators (demersal

fishes). The distribution of such suitable substrates in some locations (e.g., Bristol Bay) is extremely patchy, and it is believed that settling in areas

where such substrates are absent or limited will hasten natural mortality.

Settlement on unprotected bottom presumably will leave them exposed to

predation, waves, and currents.

Shipboard substrate preference tests were conducted with Age 1+ crab

(McMurray et ale 1984). These tests indicated that in the absence of

epifauna, young crab preferred a medium-sized rock substrate over small rock,

gravel, or sand. When small "reefs" of natural epifaunal materials were placed

on the previously bare substrates, the highest percentages of crab were found

on combinations of tube worms with sand and of mussels with small rocks.

Erect bryozoans in combination with medium-sized rock attracted the smallest

percentage of crab. Crab were observed during the experiments feeding directly

on the tube worms and scavenging food from the spaces between mussels.

Subadult and adult red king crab populations reside on variable

substrates from rocky, nearshore regions to mud, silt, or sand in deeper

offshore and some nearshore areas. The latter substrate appears to be preferred (Korolev 1964; Powell et ale 1983; Feder and Jewett 1987). A

historically important spawning area near the south end of Kodiak Island has

substrates mainly consisting of mud, silt, and sand; however, some rocky areas

also occur adjacent to the spawning ground (Kingsburg and James 1971; S.

Jewett, pers. observ.). In April 1970, during the height of the king crab

mating and spawning, an estimated 1.4 million red king crab occupied 208.7 km2

of the above area between depths of 9 and 53 m. The average crab density was

6,722 per km2 (Kingsbury and James 1971).

Vegetation

Spawning crab also occupy regions where kelp (i.e., Alaria, Costaria, and

Laminaria) occurs (Powell and Nickerson 1965a). Numerous exoskeletons of

recently molted crab were seen in a kelp bed near Kodiak Island (S. Jewett,

pers. observ.). The rocks and kelp presumably give protection to the females

while they are soft following ecdysis and during subsequent mating.

8
Food

Investigations of the food habits or feeding behavior of king crab have

been conducted in the following areas: the west Kamchatka Shelf, Okhotsk Sea,

Sea of Japan, southeastern Bering Sea, and northern Gulf of Alaska (Cook Inlet

and the Kodiak Island vicinity) (see Jewett and Feder 1982 for references

relative to the above areas; Pearson et al. 1984).

The larvae are plankton feeders consuming both phytoplankton and

zooplankton (Bright 1967). Therefore, the concurrence of the time of hatching

and the spring phytoplankton and subsequent zooplankton blooms is important in

determining larval feeding success. It appears that diatoms are an important

energy source for first feeding larvae (A.J. Paul, University of Alaska,

Seward, pers. comm.) with copepods (Paul and Paul 1980) and some meroplankton

(A.J. Paul, pers. comm.) supplying additional energy.

First zoeae that received food within 60 hours of hatching were capable

of capturing prey thereafter if prey concentrations were adequate. When

feeding was delayed an additional 24 hours, the ability to capture prey was

reduced, especially at water temperatures <4°C (Paul and Paul 1980).

Paul et al. (1979) designed a laboratory study to determine zooplankton

prey densities necessary to elicit a successful feeding response in firstfeeding zoeae of red king crab (five zoeae per 500 ml of filtered seawater).

Prey (copepod) densities had to equal 80 per liter before an average zoea was

able to consistently capture at least one prey item each day. Prey densities

of this magnitude are considerably higher than those in waters where larval

king crab are known to occur (Paul et al. 1979). Prey consumption increased

from 0.8 per day at a concentration of 20 prey items per liter to 7.6 at a

concentration of 160 prey items per liter. The survival rate to day 11 in the

container having 20 prey items per liter was 40%, and the survival rate to day

11 in beakers containing 40, 80, and 160 organisms per liter was 60%. In a

beaker containing zoeae without prey, the first mortality occurred on day 4,

and 100% mortality occurred by day 8 (Paul et al. 1979).

Although no quantitative information is available on the food of early

postlarval king crab, some qualitative information is available. Young-of-theyear crab in a coastal region of the west Kamchatka Shelf were found to feed

on hydroids, the dominant epifaunal component of the refuge substrate within

the region (Tsalkina 1969). Young-of-the-year crab (172 between 3.2 and 5.0

mm CL) from the shallow «27 m), rocky, bryozoan-dominated substrate of Cook

Inlet most frequently contained diatoms, foraminifera, sponge spicules,

bryozoans, polychaetes, and crustaceans (ostracods and harpacticoid copepods).

Sediment was also found in 93% of these tiny crab (Feder et al. 1980). Pearson

et al. (1984) reported that stomachs of 24 small juveniles (9-24 mm CL) from

the southeastern Bering Sea were mainly full of sediment, in addition to unidentifi~ble organic matter. Although the discernible items were few, the

most frequently occurring identifiable prey groups were pelecypods,

gastropods, crustaceans, and sand dollars. These studies indicate that young

crab feed on attached epifauna, as well as organisms within the sediment. It

is not known if the high incidence of sediment represents accidental ingestion

while taking larger organisms or deliberate ingestion for the extraction of

bacteria, diatoms, foraminiferans, and meiofauna.

9
The calculated values for daily ration and caloric intake for juvenile

king crab (53-80 mm CL) in the southeastern Bering Sea during June 1982 were

6.30 mg dry weight and 17.5 calories per g of crab wet weight, respectively.

Similar values for August were higher with a daily ration of 11.92 mg dry

weight and 42.2 calories per g of crab wet weight (Pearson et al. 1984). Two

polychaetes, Pectinaria sp. and a sabel lid, constituted over 50% of the

caloric intake in June and August. The sand dollar Echinarachnius parma constituted 36% of the caloric intake in June, but only 2% in August.

Bivalves constituted 3% of the caloric intake in June, but 25% in August. The

major bivalve in the August diet was a small, thin-shelled clam, Tellina sp. The dietary differences between June and August were probably seasonal or

temporal, but differences in geographic location or depth may have also been

an important factor.

Cultured postlarval king crab are cannibalistic (Nakanishi 1985).

Mollusks (mainly bivalves), crustaceans (mainly barnacles, amphipods, and

crabs), and echinoderms (mainly brittle stars, sand dollars, and sea urchins)

are generally the dominant prey of adult and subadult red king crab nearshore

as well as offshore (Feniuk 1945; Kun and Mikulich 1954; Kulichkova 1955;

McLaughlin and Hebard 1961; Takeuchi 1967; Cunningham 1969; Tarverdieva 1976;

Feder and Paul 1980; Feder and Jewett 1981b; Jewett and Feder 1982; Rusanowski

et al. 1987). Adult and subadult crab were examined from three shallow «20

m) areas around Kodiak Island in May and June 1978-79 (Feder and Jewett

1981b). Crab from these shallow waters contained 53 different prey taxa. All

crab came from variable substrates, i.e., mud, silt, sand, firm bottoms with

little or no apparent epifauna, and firm bottoms with lush, sessile epifauna. Although numerous prey types were taken, dominant prey, in terms of frequency

of occurrence, biomass, and volume, were bivalves (clams and cockles) and

barnacles (Table 4; Feder and Jewett 1981b; Feder and Jewett, unpubl.). Kulichkova (1955) also noted that the chief prey among recently molted red

king crab from 16 m in the Okhotsk Sea were bivalves and barnacles. He

suggested that the crab need to replace calcium carbonate lost during molting

Table 4. Dominant prey of adult and subadult red king crab from three shallow

locations around Kodiak Island. All crab were collected in May and June. Prey

are ranked by decreasing relative importance using an index calculated as %

frequency of occurrence x (% weight + % volume).

Location

Depth (m)

Number examined

%with food

Size range (mm CL)

Mean size (mm CL)

Near Island McLinn Island Anton Larsen Bay

5-11 9-15 6-9

88 65 69

98.8 87.7 92.7

85-148 84-149 95-173

113 108 120

Bivalves

Barnacles

Polychaetes

Echinoids

Hydroids

RAN K

1

2

3

4

5

D 0 MIN ANT

Bivalves

Tanner crab

Snails

Polychaetes

Barnacles

10

PRE Y

Barnacles

Bivalves

Snails

Polychaetes

Hydroids
and that young clams and barnacles in shallow waters during spring represent

abundant resources to fulfill this need. Takeuchi (1959) and Jewett and Feder

(1982) observed that red king crab feed most intensively in late spring.

Sessile epifauna taken by king crab in shallow Kodiak Island waters, in

addition to barnacles, were hydroids. Crab that contained hydroids at a high

frequency of occurrence came from locations which had high proportions of

sessile organisms, including hydroids (S. Jewett, pers. observ.).

The mean weight of prey found in 713 feeding individuals (65-187 mm CL)

from shallow and deep waters near Kodiak Island was 1.41 g wet weight, or 1 mg

wet weight of prey per g of crab wet weight (Jewett and Feder 1982). Similar

quantities of food have been reported in king crab of similar size from the

west coast of the Kamchatka Peninsula. The mean quantities of stomach

contents within crab of 75 and 165 mm CL approximated 0.3 and 2 g wet weight,

respectively (Takeuchi 1967). Logvinovich (1945) reported the ratio of food

weight to body weight to be much higher among smaller crab. Experiments indicate stomach residence time among juveniles (53-80 mm CL) is approximately

11 hours for soft tissue, whereas hard parts can remain in the stomach almost

indefinitely, unless regurgitated (Pearson et ale 1984). Thus, the importance

of prey possessing hard parts, i.e., mollusks, barnacles, and fishes, may tend

to be overestimated in some studies, particularly those that rely exclusively

on frequency of occurrence data.

Salinity

Little is known of the salinity tolerances of various stages of red king crab. Laboratory experiments have shown that the growth rate of zoeae is not

affected by salinities within the range of 21.7 and 39.7 parts per thousand

(ppt) (Ku~ata 1960). Further laboratory studies revealed that the optimal

salinity for larvae, under various temperatures, is 26.8-40.2 ppt (Nakanishi

1985). Values approaching 40 ppt are unlikely to occur in natural areas.

Nakanishi (1985) reported that the salinity optima narrow from first zoeae to

first postlarvae, although no values were presented. Paul et ale (1979)

reared Stage I zoeae at salinities of 32 to 33.5 ppt.

Sampling in Bristol Bay in April and June of 1983 revealed that the

greatest densities of red king crab larvae occurred at salinities between 30

and 32 ppt (salinity measured at a depth of 10 m) (McMurray et ale 1984).

Juveniles to Age 3 (approximately 67 mm CL) were most dense at bottom

salinites between 26 and 32 ppt (April, June, and September). Crab >68 mm CL

(including a few adults) were most dense at bottom salinities between 30 and

32 ppt.

Little salinity information is available concerning adult king crab.

Adults are typically present in the shallow, coastal waters off Nome, Alaska

(Norton Sound), during the ice-covered months. However, they are typically

absent from these waters during the ice-free period (C. Lean, Alaska

Department of Fish and Game, Nome; pers. comm.). Large differences in

salinity and temperature have been observed between these two periods. The

bottom salinity and temperature at 20 m during March 1971 (crab are usually

caught through the ice in March) were 34 ppt and -1.8 °C (Hood et ale 1974).

In contrast, bottom values at 10 m during August and September 1986 (crab are

11
usually absent nearshore during these months) were 22-24.5 ppt and 8.5-11 °c

(Rusanowski et al. 1987). It appears that salinity, more than temperature, may

exclude king crab from the shallow waters near Nome during much of the icefree period.

Although salinity data are meager, an optimal range from 26 to 34 ppt is

indicated for larvae, juveniles, and adults.

Temperature

Temperature is considered one of the most crucial physical factors

affecting survival and growth of red king crab of all stages. Regional and

interannual differences in bottom water temperatures may significantly affect

the rate of embryonic development in the egg and, in turn, the appropriate

time of hatch each year.

Extrusion of eggs has been observed at a water temperature of 0-2.7 °c

(McMullen 1970; Powell et al. 1973). McMullen (1970) reported the 8-blastomere

stage was attained 5-7 days after fertilization at temperatures of 2.8-4.4 °C.

Powell et al (1973) observed the 8-blastomere stage after 10-14 days at 0-1.7

°C. The first appearance of the zoeae in the eggs normally occurs in the late

fall, approximately 6 months after fertilization (Nakanishi 1985). In

laboratory trials, the optimal temperature from fertilization to the egg-zoeae

stage is 3-8 °C (Nakanishi 1985). The zoeae then overwinters in the egg, and

the optimal temperature in the laboratory is correspondingly lower: 3 °C

(Nakanishi 1985). The thermal tolerance of free-swimming zoeae has been

determined to be between 0.5 and 15°C (unspecified salinity) (Kurata 1960)

and -1.8 and 18°C at a salinity of 33.5 ppt (Nakanishi 1985). Duration of

the first free-swimming stage varies from 24 days at 2 °C to 9 days at 8 °C

(Kurata 1960). It took 84 days to raise crab to first postlarvae at water

temperatures between 3.8 and 7.8°C (Marukawa 1933). Nakanishi (1985)

stated that the optimal water temperature for survival and growth of

laboratory-reared larvae is 8°C. Kurata (1960) found the greatest survival

of zoeae to be between 5 and 10°C and formulated an equation that relates

developmental time to temperature. Larval development time can double with a

decrease of temperature from 10 to 5 °C (Kurata 1960), and an average of 460

degree days (= cumulative average daily temperature) is required for

development from hatch of egg to metamorphosis of glaucothoe (Kurata 1961a).

Paul and Paul (1980) studied the effect of temperature and starvation on

subsequent ability to capture food, and found that prey availability when

zoeae first begin to feed had more effect on later feeding success than water

temperature. First zoeae held at 2, 4, and 6 °C and first fed after 12 and 60

hours were able to successfully capture copepod prey. Zoeae held at 6 °C and

starved for 84 hours retained the ability to capture prey; however, there was

a significant reduction in predation rates in comparison to zoeae starved for

shorter periods at this temperature. Zoeae held at 2 °C and 4 °C without food

for 84 hours were unable to capture copepod prey when later presented.

Takeuchi (1962) collected larvae in the southeastern Bering Sea in April- June 1960. During this period temperatures at 10 and 50 mdepths were 1.5-5.5

°C and 1.5-2.8 °C, respectively. Larval densities in Bristol Bay in April and

12
June 1983 were highest at I-3°C and 5-7 °c, respectively (temperature measured at 10 m depth) (McMurray et ale 1984).

The effect of temperature on juvenile (30-40 mm Cl) king crab was

examined in a 90-day laboratory study (Rice et ale 1985). Crab held at 5 °C

had high overall survival (88%) because the crab had a moderate amount of

molting attempts (46%) and the highest molting success (75%). Crab at 10°C

had good overall survival (65%); all attempted to molt and 65% were

successful. Survival at 15 °C was poor (46%) because a high percentage of crab

attempted to molt (62%) and survival of molting crab was only 12%. Crab at 1

and 20°C had high survival (92% and 81%, respectively), but few attempted to

molt and none succeeded. Food consumption in these crab increased linearly

with increasing temperature. At 1°C, crab ate a daily average of 0.09 g of fish, and at 20°C, 1.0 g. There was no significant difference in growth

among crab held at 5 and 10°C (Rice et al. 1985). The optimal water

temperature for long-term rearing of juvenile crab (30-40 mm Cl) was

concluded to be 10°C, because it allowed relatively rapid molting and reasonably good survival.

Numerous young-of-the-year crab were observed beneath rocks at 6 m in an

embayment of Kodiak Island (S. Jewett, pers. observ.). The bottom temperature

during this observation in May 1978 was 5.5 °C. The distribution of juveniles

up to Age 3 (approximately 67 mm Cl) within Bristol Bay in 1983 was generally

restricted to the coastal region «50 m) (McMurray et ale 1984). Juvenile crab

of this size had their highest concentrations at bottom temperatures of I-3°C

in April, 4-10 °C in June, and 10-11 °C in September 1983 (McMurray et ale

1984). Red king crab older than Age 3 (>67 mm Cl) (including a few adults)

were mainly located at depths of 50-70 m in temperatures of I-3°C in April,

4-7 °C in June, and 9 °C in September (McMurray et al. 1984).

The known temperatures in shallow coastal areas where adult red king crab molt, mate, and spawn are mainly from the Kodiak Island area. Primiparous females in holding pens molted and mated at temperatures between -0.3 and 1.7

°C during February and March 1971 (Powell et ale 1973). Adults were observed

where bottom water temperatures at 6-12 m ranged between 5.5 and 7.0 °C in May

and June 1978 and 1979 (S. Jewett, pers. observ.). Activity mainly observed at

this time was feeding, although some molting and mating also occurred. Much

information is available on temperatures in deeper, offshore waters where

adults reside during most of the year. The bottom temperatures associated

with sublegal and legal-sized male crab at depths averaging between 50 and 60

m in the southeastern Bering Sea in June and July of 1975-85 ranged between

-1.5 and 8°C, with most found between 2 and 5 °C (Otto et ale 1982, 1983,

1984; Stevens and MacIntosh 1985). Although there were peaks in catch rates

associated with a narrow temperature range in each year, peak catches were

associated with different temperatures in different years. Stinson (1975)

correlated male and female abundance with temperature and, from several years

of National Marine Fisheries Service (NMFS) survey data, located most sexually

mature females inshore of the 4 °C isotherm in the southeastern Bering Sea.

Surveys of red king crab populations in Norton Sound in September-October 1976

and 1985 found most adults dispersed at 18-22 m, where temperatures were

between 6 and 8 °C (Wolotira et al. 1977; Stevens and MacIntosh 1986). Sato

(1958) reported that in Asiatic waters, commercial concentrations of king crab

were not found where bottom temperatures exceeded 12 cC.

13
In summary, based on laboratory and field data, king crab of different

life stages have specific temperature tolerances and optima. Optimal

temperatures for eggs are 3-8 °C. Although larvae may tolerate water-column

temperatures of -1.8 to 18 oC, survival appears to be best at 5-10 °C.

Juveniles can tolerate temperatures at least 0-15 oC, but their optimal

temperatures are thought to be 5-10 °C. While adults are in shallow waters,

mainly from March through May, they may be exposed to temperatures -1.8 to 9

oC, but 2-7 °C is assumed to be optimal, based on our interpretation of the

NMFS survey analyses.

HABITAT SUITABILITY INDEX (HSI) MODEL

Model Applicability

Geographic area. The red king crab model is applicable to the Continental

Shelf of the North Pacific Ocean (54 0 to 71 025 1 N latitude), with emphasis on

coastal waters of the Gulf of Alaska and the southeastern Bering Sea, from the

intertidal zone to around 50 m. The crab population in Norton Sound, an

embayment of the northeastern Bering Sea, is subjected to a suite of

environmental conditions unlike the conditions known for other populations.

Anomalies in depth «30 m depths throughout the Sound) and ice-covered

conditions (up to 6 months per year) suggest that the timing of various

activities, e.g., mating, may differ from populations elsewhere. Therefore,

the model should not be applied to this northern population.

Season. The model can be applied throughout the year for juveniles to Age

4. It is designed to be used for larvae for about 6 months, from March

through August. This is approximately 6 weeks longer than the longest time

suspected for larval existence (approximately 4.5 months) so that interannual

variability can be taken into account. Similarly, the model is designed for

seasonal use for adults and subadults (Age 4+ juveniles). They typically use

the coastal waters for not more that three months in spring (mainly MarchMay) .

Minimum habitat area. This is defined as the minimum area of contiguous suitable habitat required for a species to live and reproduce successfully. No

attempt has been made to establish a minimum habitat area for this species.

Verification level. The model output is an index value between 0.0 and

1.0 that reflects the habitat potential for all life stages of the crab after

the egg. The model has not been field tested. Hypothetical data sets were

used to verify the acceptability of the model output.

The following biologists have reviewed this model for accuracy and

applicability to various Alaskan coastal water areas: Robert Otto and Bradley

Stevens, National Marine Fisheries Service, Northwest and Alaska Fisheries

Center, Kodiak, Alaska; A.J. Paul, Institute of Marine Science, University of

Alaska, Seward; and Daniel Wickham, Bodega Marine Laboratories, University of

California, Bodega Bay. Their comments have been incorporated, but the

authors are responsible for the final version of this model.

14
Model Description

Overview. The requirements of red king crab differ considerably according

to life stage. Therefore, separate models are developed for larval, young-ofthe-year juvenile, Age 1 to Age 4 juvenile, and Age 4+ juvenile (subadult)

through adult life stages. Red king crab larvae are pelagic, and the model for

larval stages has only a water quality component with temperature and salinity

variables (Figure 1). All other stages are benthic. The models for benthic

stages all have the same structure, with a food/cover component derived from

one substrate variable and a water quality component consisting of temperature

and salinity variables (Figure 1). Existing salinity data are too limited to

detect differences among life stages, but tolerances are broad. In these

Life stage Habitat variable Component

Larva1 Middepth salinity March through August ______

.. 7 Water

Maximum middepth temperature

March through August

qual ity -- HSI

Substrate FOOd/c:~::>HSI

Bottom salinity all year=:> Water

Maximum bottom temperature

all year

Young-of-the-year V3 juvenile

Bottom sal i ni ty a11 year----......... __ ,/Water

Maximum bottom temperature

all year

Age 1-4 juvenile V3

V4

Substrate ---------

QUali>HSI

Food/cover

Age 4+ juvenile V7 (subadult) and

adult

Bottom sal i nity

March through May ~water quality

Maximum bottom temperature /

March through May HSI

Substrate Food/cover

Figure

Habitat

crab.

1. Relationship of habitat variables and life requisites to

Suitability Index (HSI) values for different life stages of red

the

king

15
models, salinites between 26 and 40 ppt are assumed optimal for all life

stages. Because the crab are so unresponsive to this factor, temperature is

assumed to be the more important determinant of water quality. The models

differ in their season of application and the specific relationships between

other measured variables and suitability. Usually it is inappropriate to use

all models at the same site because the requirements of some stages are

mutually exclusive. Guidance about application of models is provided under

Field Use of the Models.

Larval life stage. Conditions in the water column determine habitat

suitability for the pelagic larvae of king crab. The model has only a water

quality component, where salinity during the larval period from March through

August can range quite broadly without adversely affecting suitability. Since

the period that larvae are present in the water column is much longer than

that required for an individual to complete development (3-4.5 months), it is

possible for segments of the population to successfully complete development

even if conditions were lethal much of the March-August period before or after

they were in the water column. Therefore, the duration of the period that

salinities are in the optimal range between 26 and 34 ppt from March through

August (V 1) is a good indicator of suitability. Under ideal conditions,

larval development is completed in approximately 90 days (Marukawa 1933). It

is assumed in this model that salinities in the optimal range for at least

half this long (>45 days) are required for any successful development. Above

that threshold, the longer the duration of optimal salinities, the higher the

suitablity will be.

The temperature variable (V2 ) must take into account three responses.

(1) Starvation is likely to occur before first successful feeding below 4 °c

(Paul and Paul 1980). (2) In the laboratory, survival is high between 5 °c

and 10°C (Kurata 1960) and developmental time is half as long at 10°C as at

5 °C (Kurata 1961a). Nakanishi (1985) reported 8 °C as optimal. (3) Survival

decreases as temperature increases above 10°C, presumably because metabolism

is so high that further increase in the molt rate is physiologically

stressful. If the high risk of predation in the water column under natural

conditions is taken into account, optimal temperatures would appear to be near

10 °c, where the length of the larval period is minimized while viability

remains high.

The maximum middepth water temperature during the larval period of March

through August is an easily obtained field measurement that nevertheless can

be used to express these complex relations. If the highest temperature

achieved during the larval period is 4 °C or lower, starvation probably will

occur. If not, development will take so long that predation will be severe.

Between the two effects, unsuitability is assumed. If a maximum temperature

of 7 °C is reached, survival is high and developmental time is intermediate,

but the time that these conditions prevailed probably would be short.

Therefore, suitability would be intermediate for the whole larval period. For

a maximum of 10°C, shortest development time compatible with high survival

probably would prevail for the longest time. For still higher maxima, some

larvae will complete development before conditions become unsuitable. It is

assumed that the higher the maximum, the sooner in the larval period

unsuitable conditions will ensue and the fewer larvae will complete

development, to the point that none are successful at a maximum of 20 °C.

16
Young-of-the-year and ¥ounS juvenile (A~e 1-4) life stages. The same

water quality component appl1es 1n both juven1le stage HSI models. Similar

water quality variables apply as for the larval life stage, except that the

measurements are for conditions on the bottom and year-round. It is assumed

that considerably longer periods in the 26- to 34-ppt salinity range (V3 ) are

required for high suitability than is the case for the larval stage and that

suitability decreases linearly from 1.0 at 12 months in the optimal range to a

when salinities are never in the optimal range. Since juveniles reared at 5

and 10 °C had high molting success (Rice et ale 1985), maximum temperatures

(V 4 ) of 5-10 °C appear to be optimal. Unsuitable conditions presumably exist

when maximum temperatures are <1°C or >16 °C (Rice et al. 1985). Suitability

decreases more rapidly at high maximum temperatures than is the case for

larvae, because the whole population of juveniles, but not of larvae, is at

risk at the same time. In contrast, many larvae may have successfully

completed development and may no longer be in the water column when unsuitable

temperatures are reached there.

The food/cover component is defined by slightly different substrate

variables for young-of-the-year (V s) and Age 1-4 (V6 ) juveniles, as a

consequence of the decreasing need for cover as juveniles grow. The decreased

vulnerability of larger individuals allows them to exploit the alternative

food resources provided by adjacent soft-bottom areas, and these changes are

reflected in different suitability index values for the same substrate

classes, depending on age.

Subadult (Age 4+) and adult life stages. Subadult and adult red king crab

engage in inshore-offshore migrations and are typically only present in

shallow coastal waters from March through May. The water quality variables

are adjusted accordingly. Suitability is assumed to increase linearly the

longer that salinities are in the 26- to 34-ppt range (V 7)' Maximum

temperatures (Va) are assumed unsuitable below 2 °C and above 15°C, optimal

at 7°C, and to change linearly between 2 and 7 °C and between 7 and 15°C.

The food/cover component is determined by a substrate variable (V 9)' with

finer substrates assigned slightly higher suitabilities than for Age 1-4

juveniles.

Suitability Index (SI) Graphs for Model Variables

This section provides graphic representations of the relations previously

described between the habitat variables (V 1-V9 ) and habitat suitability for

different life stages of red king crab in coastal waters. An SI value of 1.0

indicates optimal conditions and a value of a indicates unsuitable conditions.

Data sources and assumptions associated with documentation of the SI graphs

are listed in Table 5.

17
Variable Suitability Graph

VI Salinity - number of days March 1.

through August with 26- to 34-ppt

middepth salinity - larvae.

)( 0.8

Q)

.5 0.6

>- ::

:a 0.4

as

-i 0.2

0.0

0 45 90 135 180

Days

V Maximum middepth water 1.

2 temperature March through August - larvae.

)( 0.8

Q)

.5 0.6

>- :=

:a 0.4

as

"5-(I) 0.2

o.

-5 0 +5 +10 +15 +20 +25

o C

V 1.

3 Salinity - number of months during

the year with 26- to 34-ppt bottom

salinity - young-of-the-year )( 0.8

juvenil es. Q)

.5 0.6 ....

::

:a 0.4

as

"5-(I) 0.2

0.0

Months

18
Variab1e Suitability Graph

1.

)( 0.8

CD

"

oS 0.6

>-

:a

= 0.4

II

:c

tIJ 0.2

o.

-5 +5 +10 +16 +20+26

o C

V4 Maximum bottom water temperature

during year - young-of-the-year

and Age 1-4 juveniles.

fo

-

Vs Substrate class - young-of-the-year 1.0

juveni lese

)( 0.8

1) Bare bedrock CD

2) Bare rocks, gravel, shell "

oS 0.6 3) Bedrock, rocks, gravel, shell with >-

sessile epifauna/flora

4) Substrate with sessile :a= 0.4

epifauna/flora adjacent to soft II

:

bottom areas 0.2 5) Soft bottom - sand, mud. tIJ

0.0 1 2 3

Class

4 5

fo

V6 Substrate class - Age 1-4 juveniles. 1.0

1) Bare bedrock )( 0.8

2) Bare rocks, gravel, shell CD

3) Bedrock, rocks, gravel, shell with "

c

- 0.6 sessile epifauna/flora >- 4) Substrate with sessile

epifauna/flora adjacent to soft :a

= 0.4 II bottom areas :c

5) Soft bottom - sand, mud. tIJ 0.2

0.0 1 2 3

Class

4 6

19
Variable Suitability Graph

V7 Salinity - number of days March 1.

through May with 26- to 34-ppt

bottom salinity - subadults

)( 0.8 and adults. G)

'0

.5 0.6

:!::

--.Q 0.4

aJ

.-.;

t/) 0.2

0.0

0 30 60 90 120

Days

1. Vs Maximum bottom water temperature

March through May - subadults

and adults. )( 0.8

G)

'0

.5 0.6

:!::

.--.Q 0.4

aJ

.-";

t/) 0.2

0.0

-5 0 +5 +10 +15 +20 +25

o C

V9 Substrate class - subadults and

adults.

)(

1) Bare bedrock G)

'0

2) Bare rocks, gravel, shell c

- 3) Bedrock, rocks, gravel, shell with

sessile epifauna/flora 4) Substrate with sessile .Q

aJ epifauna/flora adjacent to soft :!::

bottom areas ::::I

t/)

5) Soft bottom - sand, mud.

1.0

0.8

0.6

0.4

0.2

0.0

1 2 3

Class

4 5

20
Table 5. Data sources and assumptions for red king crab suitability indices.

Variable and source Assumptions

V1,3,7 Kurata 1960

Paul et al. 1979

McMurray et al. 1984

Nakanishi 1985

Marukawa 1933

Kurata 1960, 1961a

Takeuchi 1962

Paul and Paul 1980

McMurray et al. 1984

Nakani shi 1985

McMurray et al. 1984

Rice et al. 1985

Jewett, unpubl.

Probable optimal salinities for

larvae, juveniles, and adults are

26-34 ppt.

Tolerance is reported variously as

-1.8 to +18 °c or 0.5-15 °C; survival

is best at 5-10 °C; development is

twice as fast at 10°C as at 5°C;

development is optimal in the

laboratory at 8 oC; starvation before

first meal is likely at <4°C.

Molting success is high in the laboratory at 5-10 °C; survival is better at

5 °C than at 10°C, but frequency of

molting at 5 °C is half that at 10°C;

only 12% of crab molting at 15 °C

survive; no molting occurs at 1 and 20

°C; field observations are consistent

with these laboratory determinations.

Vs Powell and Nickerson 1965b

Tsalkina 1969

Sundberg and Clausen 1977

McMurray et al. 1984

V6 Feder et al. 1980

McMurray et al. 1984

Pearson et al. 1984

Sato 1958

Wolotira et al. 1977

Otto et al. 1982, 1983, 1984

Stevens and MacIntosh 1985

Jewett , unpubl.

Coarse substrates with sessile

epifauna/flora are optimal by

providing food and cover; soft bottoms

are low in suitability; bare bedrock

is unsuitable.

Soft bottoms are more suitable for Age

1-4 juveniles than for the young of

the year, because larger individuals

can forage more successfully in the

surface layers of the sediment and are

less vulnerable to predators; however,

coarse material with epifauna/flora is

still valuable for food and cover.

Subadults and adults are exposed to

temperatures from -1.8 to 9°C; the

optimal range is 2-7 °C.

(continued)

21
Table 5. Concluded.

Variable and source Assumptions

Feniuk 1945

Kun and Mikulich 1954

Kulichkova 1955

McLaughlin and Hebard 1961

Korolev 1964

Powell and Nickerson 1965a

Takeuchi 1967

Cunningham 1969

Kingsbury and James 1971

Tarverdieva 1976

Feder and Paul 1980

Feder and Jewett 1981b

Jewett and Feder 1982

Powell et al. 1983

Feder and Jewett 1987

Subadult and adult red king crab

reside on substrates ranging from

rock to mud; soft bottoms seem to be

preferred slightly offshore t but

coarse substrate with sessile

epifauna/flora adjacent to soft bottom

is assumed optimal inshore for feeding

and allowing protection for females

during the necessary molt for

reproduction.

Component Index Equations and HSI Determination

The Habitat Suitability Index (HSI) model for the larval life stage of

red king crab has only a water quality component in which temperature is

considered to be more important than salinity. It is assumed that high

suitability for one variable can partially compensate for low suitability for

the other variable t except that unsuitable conditions for one variable will be

limiting. Therefore t a weighted geometric mean is used to combine salinity

and temperature SI values into the water quality component index (CI) and HSI.

The HSI models for juvenile and adult life stages are composed of water

quality components of the same form as for the larval stage t plus a food/cover

component equal to the SI for the substrate variable. No compensatory

relationships between water quality and food/cover components are assumed to

operate. Therefore t the HSI for these stages is the lower of the two CI

values. Examples of model outputs using hypothetical data sets appear in

Table 6.

Life Stage Component Equation

Larval Water qual ity (WQ) [SIV x (SI )2 J1/3

1 V2

HSI = WQ

Young-of-the-year WQ [SIV x (SI )2J1I3

juvenile 3 V4

Food/cover (FC) SI

vs

HS I = WQ or FC t whichever is lower

22
Life 5tage Component Equation

Age 1-4 juvenile WQ [5IV 3 x (51 )2]1/3 V4

FC 51V6

H5 I = WQ or FC, whichever is lower

Age 4+ j uvenil e WQ [51V7

x (51 )2 ]1/3

and adult VB

FC 51V9

H5 I = WQ or FC, whichever is lower

Table 6. Calculation of suitability indices (51), component indices (CI), and

habitat suitabil i ty indices (HSI) for three hypothetical data sets using habitat variable (V) measurements and red king crab H51 model equations.

Model Data set 1 Data set 2 Data set 3

component Data 51 Data 51 Data 51

VI days 180 1.00 150 0.78 90 0.33

V2 °C 8 0.67 6 0.33 4 0.00

V3 months 10 0.83 6 0.50 4 0.33

V4 °C 8 1.00 4 0.80 1 0.20

Vs Class 3 1.00 2 0.50 5 0.10

V6 Class 3 0.80 2 0.40 5 0.80

V7 days 120 1.00 60 0.50 30 0.25

VB °C 7 1.00 4 0.40 1 0.00

Vg Class 3 0.70 2 0.30 5 0.90

WQ larvae 0.77 0.44 0.00

young-of-the-year 0.94 0.68 0.24

Age 1-4 0.94 0.68 0.24

Age 4+ 1.00 0.43 0.00

FC young-of-the-year 1.00 0.50 0.10

Age 1-4 0.80 0.40 0.80

Age 4+ 0.70 0.30 0.90

H51 larvae 0.77 0.44 0.00

young-of-the-year 0.94 0.50 0.10

Age 1-4 0.80 0.40 0.24

Age 4+ 0.70 0.30 0.00

Field Use of the Models

The most important step in the proper application of the red king crab

H51 models is model selection. Usually it is inappropriate to aggregate

results of models for different life stages applied at the same location.

23
Since the different life stages have conflicting requirements, most approaches

to aggregation will yield intermediate results that are unresponsive to

changes in conditions. Changes that increase suitability for one life stage

decrease suitability for another. The lack of response of the aggregate HSI

could be very misleading if the life stage that was adversely affected was

limiting the population.

In many cases, knowledge about the biology of the crab in the proposed

study area will provide the needed guidance for proper model selection.

Almost certainly an area will not be equally important for all life stages. If

it is known or strongly suspected that an area is especially significant for a

life stage, then this should dictate the choice of models. Alternatively, even

though an area is known to be particularly important for one life stage,

another life stage might be selected for evaluation if it is known to be

limiting for the population as a whole. The young-of-the-year life stage is

the most likely candidate.

Two other options are available when prior knowledge is insufficient to

rank the importance of a location for different life stages. All the models

can be applied for baseline conditions and the model selected for the life

stage that has the highest HSI. In this case, the assumption is that the

study area is most important to the life stage that does best there under

baseline conditions. In the absence of other information, this assumption may

be acceptable, but even here judgment should be exercised. A relatively poor

area for a life stage may nevertheless be the best there is and critical for

the population, a possibility that would not be accounted for with this

approach.

The other option is to perform before and after comparisons using all

life stages and select the life stage most adversely affected for assessing

project impacts. This approach also has the drawback that the life stage

suffering the largest impact may not be the stage for which habitat is

limiting to the stock as a whole.

It should be recognized that these models do not take into account

some aspects of red king crab habitat that may be more critical than those

addressed. Among these, factors responsible for water column stability and

upwelling are critical in determining the availabilty of the planktonic food

supply for larval stages. Currents and local patterns of water circulation

will determine whether or not larvae will be carried to areas suitable for

juvenile rearing after settlement. Probably both of these aspects are more

important influences on habitat suitability for the larval stage than the

water quality factors included in this model. Unfortunately, data are not

available to formulate models that incorporate larval food supply and access

to juvenile rearing areas, and general models will never be feasible. In local

situations, these factors may be amenable to analysis and users should take

them into consideration. Guidance on obtaining the necessary information to

apply the models is provided in Table 7.

Interpreting Model Outputs

The proper interpretation of the red king crab HSI models is one of

comparison. The models can be used to compare different areas at the same

24
time or the same area at different times. Provided that the model for the

limiting life stage was selected and that larval food and larval access to

juvenile-rearing areas do not overwhelm the effects measured by these models,

areas with higher HSI values should support larger red king crab populations.

Table 7. Suggested techniques for obtaining the data necessary to apply the red king crab HSI models.

Variable

V5.6,9

Techniques

Long-term salinity records are desirable. Surveys of the National

Marine Fisheries Service, Alaska Department of Fish and Game, and

University of Alaska Institute of Marine Science may be the best

sources of this information. Field measurements should be made at

middepth with a probe or from water samples collected at middepth by

titration, refractometer, hydrometer, or conductivity meter

(Strickland and Parsons 1968). Limited observations will be

adequate, if they are made at the known time of most extreme

salinity conditions and values still are in the 26- to 34-ppt range.

When measurements fall outside this range, monthly or more frequent

sampling from March through August is desirable.

Long-term temperature records are desirable. The same sources listed

for VI should be consulted. In addition, satellite remote monitoring of sea surface temperature is being conducted. The National Ocean

Surveyor National Weather Service should be contacted about the

availability of monitoring records for Alaskan coastal waters. If

surface temperatures are available, it will be necessary to

determine the relationship between surface and middepth temperatures

before application in the model. When only limited field

measurements are possible, the measurements should be made in July and August, when maximum temperature during the larval period is

bound to occur. Temperature should be measured with a probe at

middepth or with a thermometer in a water sample immediately after

collection at middepth.

Same as VI' except measurements should be at the bottom and for the

whole year.

Same as V2 , except measurements should be at the bottom and for the

whole year.

Three grab samples should be collected while the boat is anchored at

the same location. The substrate is Class 1 if all three samples are

empty; Class 2 if bare coarse material is dominant in all three

samples; Class 3 if coarse material with sessile epifauna or sessile

epifauna alone is dominant in all three samples; Class 4 if mud and

coarse material with sessile epifauna are dominant in different

samples from the same location; Class 5 if mud or sand is dominant

(continued)

25
Variable

Table 7. Concluded.

Techni ques

V5,6,9 (cont/d)

in all three samples. Intermediate values should be assigned when

different substrates are dominant among samples collected at the

same location, except as specified for Class 4. Users should have

little difficulty in adapting these criteria for visual

determinations made by diving.

V7 Same as VI' except measurements should be at the bottom and for

March through May.

Va Same as V2 , except measurements should be at the bottom and for

March through May.

26
REFERENCES

Alaska Department of Fish and Game. 1985a. Shellfish. report to the Alaska

Board of Fisheries. Lower Cook Inlet Management Area. Rep. 85-4. Div. Comm.

Fish., Homer, Alaska. 56 pp.

Alaska Department of Fish and Game. 1985b. Shellfish report to

Board of Fisheries. Prince William Sound Management Area. Rep.

Comm. Fish., Homer, Alaska. 54 pp.

the Alaska

85-2. Div.

Alaska Department of Fish and Game. 1985c. Shellfish report to the Alaska

Board of Fisheries. Westward Region Management Area. Div. Comm. Fish.,

Kodiak, Alaska. 346 pp.

Alaska Department of Fish and Game. 1985d. Shellfish report to the Alaska

Board of Fisheries. Southeast Alaska-Yakutat Management Areas. Div. Comm.

Fish., Petersburg, Alaska. 102 pp.

Alaska Department of Fish and Game. 1986. Westward region shellfish report to

the Alaska Board of Fisheries. Div. Comm. Fish., Kodiak, Alaska. 329 pp.

Armstrong, D.A. 1983. Cyclic crab abundance and relationship to environmental

causes. Pages 102-110 in W. Wooster, ed. From year to year: interannual

variability of the environment and fisheries of the Gulf of Alaska and

eastern Bering Sea. Washington Sea Grant Publ. WSG-WO-83-3. University of

Washington, Seattle.

Armstrong, D.A., L.S. Incze, D.L. Wencker, and J.L. Armstrong. 1981.

Distribution and abundance of decapod crustacean larvae in the southeastern

Bering Sea with emphasis on commercial species. U.S. Dep. Commer., NOAA,

OCSEAP Final Rep. 53(1986):479-878.

Balsiger, J.W. 1974. A computer simulation model for the eastern Bering Sea

crab population. Ph.D. Dissertation. University of Washington, Seattle.

198 pp.

Blau, S.F. 1986. Recent declines of red king crab (Paralithodes camtschatica)

populations and reproductive conditions around the Kodiak Archipelago,

Alaska. Pages 360-369 in G.S. Jamieson and N. Bourne, eds. North Pacific

workshop on stock assessment and management of invertebrates. Can. Spec.

Publ. Fish. Aquat. Sci. 92.

Bright, D.B. 1967. Life histories of the king crab, Paralithodes camtschatica,

and the "Tanner" crab, Chionoecetes bairdi, in Cook Inlet, Alaska. Ph.D.

Dissertation. University of Southern California, Los Angeles. 265 pp.

27
Butler, T.H., and J.F.L. Hart. 1962. The occurrence of the king crab,

Paralithodes camtschatica (Tilesius), and of Lithodes aequispina Benedict in

British Columbia. J. Fish. Res. Board Can. 19(3):401-408.

Cunningham, D.T. 1969. A study of the food and feeding relationships of the

Alaskan king crab, Paralithodes camtschatica. M.S. Thesis. San Diego State

College, San Diego. 78 pp.

Feder, H.M., and S.C. Jewett. 1977. The distribution, abundance, biomass and

diversity of the epifauna of two bays (Alitak and Ugak) of Kodiak Island,

Alaska. University of Alaska, Institute of Marine Science, Rep. No. R77-3.

74 pp ,

Feder, H.M., and S.C. Jewett. 1981a. Feeding interactions in the eastern

Bering Sea with emphasis on the benthos. Pages 1229-1261 D.W. Hood and

J.A. Calder, eds. The eastern Bering Sea shelf: oceanography and resources.

Vol. 2. University of Washington Press, Seattle.

Feder, H.M., and S.C. Jewett. 1981b. Distribution, abundance, community

structure and trophic relationships of the nearshore epibenthos of the

Kodiak Continental Shelf. University of Alaska, Institute of Marine Science,

Rep. No. R81-1. 216 pp.

Feder, H.M., and S.C. Jewett. 1987. The subtidal benthos. Pages 347-396 in

D.W. Hood and S.T. Zimmerman, eds. Gulf of Alaska: physical environmenI

and biological resources. Government Printing Office, Washington, D.C.

Feder, H.M., and A.J. Paul. 1980. Food of the king crab, Paralithodes

camtschatica, and the Dungeness crab, Cancer magister, in Cook Inlet, Alaska.

Proc. Natl. Shellfish. Assoc. 70:240-246.

Feder, H.M., K. McCumby, and A.J. Paul. 1980. The food of post-larval king

crab, Paralithodes camtschatica, in Kachemak Bay, Alaska (Decapoda,

Lithodidae). Crustaceana 39:315-318.

Feniuk, V.F. 1945. Analysis of stomach contents of king crab. [In Russian,

Japanese and Engl ish] J. Pac , Sci. Res. Inst. Mar. Fish. Oceanogr. (TINRO)

Izvestiya 19:71-78.

Fukuhara, F.M. 1985. Biology and fishery of southeastern Bering Sea red king

crab (Paralithodes camtschatica, Tilesius). Northwest and Alaska Fish. Cent.

Process. Rep. 85-11. NMFS/NWAFC, Seattle.

Gray, G.W., Jr.; and G.C. Powell. 1966. Sex ratio and distribution of

spawning king crabs in Alitak Bay, Kodiak Island, Alaska (Decapoda Anomura,

Lithodidae). Crustaceana 10:303-309.

Haflinger, K.E., and C.P. McRoy. 1983. Yellowfin sole (Limanda

predation on three commercial crab species (Chionoecetes opilio, C.

and Paralithodes camtschatica) in the southeast Bering Sea. Final~

NMFS, Contract No. 82-ABC-00202. 28 pp.

28

aspera)

baird; , Rep. to
Hayes, M.L. 1983. Variation in the abundance of crab and shrimp with some

hypotheses on its relationship to environmental causes. Pages 86-101 in W.

Wooster ed. From year to year: interannual variability of the environment

and fisheries of the Gulf of Alaska and eastern Bering Sea. Washington Sea

Grant Publ. WSG-WO-83-3. University of Washington, Seattle.

Hayes, M.L., and D.T. Montgomery. 1963. Movements of king crabs tagged and

released in Shumagin Islands area, 1957-62. U.S. Fish Wildl. Servo Spec. Sci. Rep. Fish. No. 458. 7 pp ,

Haynes, E. 1968. Relation of fecundity and egg length to carapace length in

the king crab, Paralithodes camtschatica. Proc. Natl. Shellfish. Assoc.

58:60-62.

Hirschhorn, G. 1966. Variation in biomass of eastern Bering Sea king crab based on tagging estimates of growth and mortality. U.S. Dep. Commer.,

NOAA/NMFS, Seattle, Washington, Unpubl. Rep. 24 pp.

Hood, D.W., V. Fisher, D. Nebert, H. Feder, G.J. Mueller, D. Burrell, D.

Boisseau, J.J. Goering, G.D. Sharma, D.T. Kresge, and S.R. Fison. 1974.

Environmental study of the marine environment near Nome, Alaska. University

of Alaska, Institute of Marine Science, Rep. No. 74-3. 265 pp.

Hughes, J.T., and G.C. Mattiessen. 1962. Observations of the American lobster,

Homarus americanus. Limnol. Oceanogr. 7(3):414-421.

Incze, L.S., R.S. Otto, and M.K. McDowell. 1986. Recruitment variability of

juvenile red king crab, Paralithodes camtschatica, in the southeastern

Bering Sea. Pages 370-378 in G.S. Jamieson and N. Bourne, eds. North

Pacific workshop on stock assessment and management of invertebrates. Can.

Spec. Publ. Fish. Aquat. Sci. 92.

Jewett, S.C., and H.M. Feder. 1982. Food and feeding habits of the king crab Paralithodes camtschatica near Kodiak Island, Alaska. Mar. Biol. 66:243-250.

Jewett, S.C., and G.C. Powell. 1981. Nearshore movement of king crab. Alaska

Seas and Coast 9(3):6-8.

Kingsburg, A.P., and K.E. James. 1971. Abundance and composition of king crabs

in the Alitak and Kaguyak Bay areas during April and June, 1970. Alaska Dep. Fish Game Inf. Leafl. 152. 42 pp.

Korolev, N.G. 1964. The biology and commercial exploitation of the king crab

Paralithodes camtschatica (Tilesius) in the southeastern Bering Sea. Pages

102-108 in P.A. Moiseev, ed. Soviet fisheries investigations of the North

Pacific.-Pt. 2. Proc. All-Union Sci. Res. Inst. Mar. Fish. Oceanogr. (VNIRO)

Trudy, Vol. 49. (Israel Program for Scientific Translations TT67-51204.)

Kul i chkova, V.A. 1955. Feedi ng of Kamchatka crabs duri ng the spri ng-surnmer period on the shores of Kamchatka and Sakhalin. [In Russian and English.]

J. Pac. Sci. Res. Inst. Mar. Fish. Oceanogr. (TINRO) Izvestiya 43:21-42.

29
Kun, M.S. and L.V. Mikulich 1954. Diet composition of far eastern crabs of

commercial quality during the summer. [In Russian, Japanese and English.]

J. Pac. Sci. Res. Inst. Mar. Fish. Oceanogr. (TINRO) Izvestiya 41:319-332.

Kurata, H. 1960. Studies on the larva and post-larva of Paralithodes

camtschatica. 3. The influence of temperature and salinity on survival and

growth of the larva. Bull. Hokkaido Reg. Fish. Res. Lab. No. 21:9-14.

Kurata, H. 1961a. Studies on the larva and post-larva of Paralithodes

camtschatica. 4. Growth of the post-larva. Hokkaido Prefectural Fish. Exp.

Stn., Month. Rep. 18(1):1-9.

Kurata, H. 1961b. On the age and growth of king crab Paralithodes

camtschatica. Hokkaido Prefectural Fish. Exp. Stn., Month. Rep. 18(1):10-22.

Logvinovich, D.N. 1945. Aquaria observations on the feeding of king crabs. [In

Russian, Japanese and English.] J. Pac. Sci. Res. Inst. Mar. Fish. Oceanogr.

(TINRO) Izvestiya 19:1-79.

MacGinitie, G.E. 1955. Distribution and ecology of the marine invertebrates

of Point Barrow, Alaska. Smithsonian Misc. Collect. 128:1-201.

Marukawa, H. 1933. Biological and fisheries research on Japanese king crab

Paralithodes camtschatica (Tilesius). [In Japanese with English summary.] J.

Imp. Fish. Exp. Stn. Tokyo 4(37):1-152.

Matsuura, S., and K. Takeshita. 1985. Development and decrease in number of

eggs attached to pleopods of laboratory-reared king crab, Paralithodes

camtschatica (Tilesius). Pages 155-165 in Proceedings of the international

king crab symposium, Lowell Wakefield Flsheries Symposium Series, January

1985, University of Alaska, Alaska Sea Grant Rep. No. 85-12. 507 pp.

Matsuura, S., K. Takeshita, and H. Kawasaki. 1972. Reproduction and fecundity

of the female king crab, Paralithodes camtschatica (Tilesius), in the waters

off western Kamchatka - II. Determination of the fecundity based on the

counts of the ovarian eggs and of the spawned eggs attached to pleopods. Far

Seas Fish. Res. Lab. Bull. 6:169-190.

McCaughran, D.A., and G.C.

Paralithodes camtschatica.

Powell. 1977. Growth model for Alaska king crab

J. Fish. Res. Board Can. 34(7):989-995.

McLaughlin, P.A., and J.F. Hebard. 1961. Stomach contents of the Bering Sea king crab. Int. N. Pac. Fish. Comm. Bull. 5:5-8.

McMullen, J.C. 1967.

in ocean environment.

Breeding king crabs Paralithodes camtschatica

J. Fish. Res. Board Can. 24:2627-2628.

located

McMullen, J.C. 1970. Aspects of early development and attachment of fertilized

king crab eggs. Alaska Dep. Fish Game Inf. Leafl. 140. 12 pp.

McMullen, J.C., and H.T. Yoshihara. 1969. Fate of unfertilized eggs in king

crabs Parlithodes camtschatica (Tilesius). Alaska Dep. Fish Game Inf. Leafl.

127. 14 pp.

30
McMurray, G., A.H. Vogel, P.A. Fishman, D.A. Armstrong, and S.C. Jewett. 1984.

Distribution of larval and juvenile red king crabs (Paralithodes

camtschatica) in Bristol Bay. U.S. Dep. Commer., NOAA, OCSEAP Final Rep.

53(1986):267-477.

Nakanishi, T. 1985. The effects of the environment on the survival rate,

growth and respiration of eggs, larvae and post-larvae of king crab

(Paralithodes camtschatica). Pages 167-185 in Proceedings of the international king crab symposium, Lowell WakefTeld Fisheries Symposium

Series, January 1985, University of Alaska, Alaska Sea Grant Rep. No. 85-12.

507 pp.

Nakazawa, K. 1912. A study of the Hokkaido king crab. [In Japanese.] Tokyo,

Dobutsugaku Zasshi (Zoological Magazine) 24(279):1-13.

Orlov, Y.I., and B.G. Ivanov. 1978. On the introduction of the Kamchatka

king crab Paralithodes camtschatica (Decapoda: Anomura: Lithodidae) into the

Barents Sea. Mar. Biol. 48:373-375.

Otto, R.S. 1985. Management of Alaskan king crab stocks in relation to the

possible effects of past policies. Pages 447-481 in Proceedings of the

international king crab symposium, Lowell Wakefiel~ Fisheries Symposium

Series, January 1985, University of Alaska, Alaska Sea Grant Rep. No. 85-12.

507 pp.

Otto, R.S. 1986. Management and assessment of eastern Bering Sea king crab stocks. Pages 83-106 in G.S. Jamieson and N. Bourne, eds. North Pacific

workshop on stock assessment and management of invertebrates. Can. Spec. Publ. Fish. Aquat. Sci. 92.

Otto, R.S., A.K. Fukuyama, T.M. Armetta, R.A. MacIntosh, and J. McBride. 1980.

King and tanner crab research in the eastern Bering Sea, 1979. Pages 78-95

Int. N. Pac. Fish. Comm., Annu. Rep. 1979. 95 pp.

Otto, R.S., R.A. MacIntosh, T.M. Armetta, and W.S. Meyers. 1982. Report to

industry on the 1982 eastern Bering Sea crab survey. Northwest and Alaska

Fish. Cent. Process. Rep. 82-13. NMFS/NWAFC, Kodiak, Alaska.

Otto, R.S., R.A. MacIntosh, K.L. Stahl-Johnson, and S.J. Wilson. 1983. Report

to industry on the 1983 eastern Bering Sea crab survey. Northwest and Alaska

Fish. Cent. Process. Rep. 83-18. NMFS/NWAFC, Kodiak, Alaska.

Otto, R.S., R.A. MacIntosh, K.L. Stahl-Johnson, and S.J. Wilson. 1984. Report

to industry on the 1984 eastern Bering Sea crab survey. Northwest and Alaska

Fish. Cent. Process. Rep. 84-17. NMFS/NWAFC, Kodiak, Alaska.

Paul, A.J., and J.M. Paul. 1980.

feeding success of king crab zoeae.

The effect of early starvation on later

J. Exp. Mar. Biol. Ecol. 44:247-251.

Paul, A.J., J.M. Paul, P.A. Shoemaker, and H.M. Feder. 1979. Prey

concentrations and feeding response in laboratory-reared stage-one zoeae of

king crab, snow crab, and pink shrimp. Trans. Am. Fish. Soc. 108:440-443.

31
Pearson, W.H., D.L. Woodruff, and B.J. Higgins. 1984. Feeding ecology of

juvenile king and Tanner crab in the southeastern Bering Sea. U.S. Dep.

Commer., NOAA, OCSEAP Final Rep. 53(1986):155-265.

Powell, G.C. 1967. Growth of king crab in the vicinity of Kodiak Island,

Alaska. Alaska Dep. Fish Game Inf. Leafl. No. 92. 106 pp.

Powell, G.C., and R.B. Nickerson. 1965a. Reproduction of king crabs,

Paralithodes camtschatica (Tilesius). J. Fish. Res. Board Can. 22(1):101- 111.

Powell, G.C., and R.B. Nickerson. 1965b. Aggregations among juvenile king crab

(Paralithodes camtschatica Tilesius), Kodiak, Alaska. Anim. Behav. 13(2-

3):374-380.

Powell, G.C., B. Shafford, and M. Jones. 1973. Reproductive biology of young

adult king crabs Paralithodes camtschatica (Tilesius) at Kodiak, Alaska.

Proc. Natl. Shellfish. Assoc. 63:77-87.

Powell, G.C., K.E. James, and C.L. Hurd. 1974. Ability of male king crab,

Paralithodes camtschatica, to mate repeatedly, Kodiak, Alaska, 1973. U.S.

Fish Wildl. Servo Fish. Bull. 72:171-179.

Powell, G.C., R. Peterson, and L. Schwarz. 1983. The red king crab,

Paralithodes camtschatica (Tilesius) in Norton Sound, Alaska: history of

biological research and resource utilization through 1982. Alaska Dep. Fish

Game Inf. Leafl. No. 222. 104 pp.

Reeves, J.E., and R. Marasco. 1980. An evaluation of alternative management options for the southeastern Bering Sea king crab fishery. Northwest and

Alaska Fish. Cent. Process. Rep. 80-6., Seattle, Washington.

Rice, S.D., C. Brodersen, and P.J. Arasmith. 1985. Feeding rates, molting

success, and survival of juvenile red king crabs at different temperatures.

Pages 187-191 in Proceedings of the international king crab symposium. Lowell WakefieldiFisheries Symposium Series, January 1985, University of

Alaska, Alaska Sea Grant Rep. No. 85-12. 507 pp.

Rodin, V.E. 1970. Some data on the distribution of king crab (Paralithodes

camtschatica Tilesius) in the southeast Bering Sea. J. Pac. Sci. Res. Inst.

Mar. Fish. Oceanogr. (TINRO) Izvestiya 72:143-148.

Royer, T.C. 1985. Coastal temperature and salinity anomalies in the northern

Gulf of Alaska, 1970-84. Pages 107-115 in W.S. Wooster and D.L. Fluharty,

eds., El Nino North, Nino effects in the eastern subarctic Pacific Ocean.

Washington Sea Grant, University of Washington, Seattle. 312 pp.

Rusanowski, P.C., L.A. Gardner, and S.C. Jewett. 1987. Nome offshore placer

project. Annual report. Prepared for Inspiration Gold, Inc ; , Nome,

Alaska. 212 pp. + appendixes.

32
Sato, S. 1958. Studies of larval development and fishery biology of king crab,

Paralithodes camtschatica (Ti1esius). Bull. Hokkaido Reg. Fish. Res. Lab.

No. 17. 102 pp ,

Shimada, A., and J. June. 1982. Eastern Bering Sea Pacific cod food studies.

NOAA/NMFS/NWAFC, Seattle, Washington. Unpub1. Rep. 41 pp.

Simpson, R.R., and H.H. Shippen. 1968. Movement and recovery of tagged king crabs in the eastern Bering Sea, 1955-63. Int. N. Pac. Fish. Comm. Bull.

24:111-123.

Sparks, A.K., and J.F. Morado. 1985. A preliminary report on the diseases of

Alaska king crab. Pages 333-339 in Proceeding of the international king crab symposium, Lowell Wakefield FTSheries Symposium Series, January 1985,

University of Alaska, Alaska Sea Grant Rep. 85-12. 507 pp.

Stevens, B.G., and R.A. MacIntosh. 1985. Report to industry on the eastern

Bering Sea crab survey. Northwest and Alaska Fish. Cent. Process. Rep. 85-

20. NMFS/NWAFC, Kodiak, Alaska.

Stevens, B.G., and R.A. MacIntosh. 1986. Analysis of crab data from the 1985

NMFS survey of the northeast Bering Sea and Norton Sound. Northwest and

Alaska Fish. Cent. Process. Rep. 86-16. NMFS/NWAFC, Kodiak, Alaska.

Stinson, J.E. 1975. The effects of ocean currents, bottom temperatures, and

other biological considerations in regard to the location and abundance of

mature southeastern Bering Sea king crab, Paralithodes camtschatica.

University of Washington., Fish. Res. Inst. Co11. Fish. Course Proj. 11 pp. (Un pub 1. Rep.)

Strickland, J.D.H., and T.R. Parsons. 1968. A practical handbook of sea water

analysis. Bull. Fish. Res. Board Can. No. 167. 311 pp.

Sundberg, K.A., and D. Clausen. 1977. Post-larval king crab (Para1ithodes

camtschatica) distribution and abundance in Kachemak Bay, Lower Cook Inlet,

Alaska, 1976. Pages 1-36 in L.L. Trasky, L.B. Flagg, and D.C. Burbank, eds.

Environmental studies of Kachemak Bay and Lower Cook Inlet. Vol. 5. Alaska

Dep. Fish Game, Anchorage, Alaska.

Takeuchi, I. 1959. Food of king crab (Para1ithodes camtschatica) off the west

coast of Kamchatka in 1958. Bull. Hokkaido Reg. Fish. Res. Lab. No. 20:67-

75. (Fish. Res. Board Can. Transl. Sere No. 1193, 1968.)

Takeuchi, I. 1962. On the distribution of zoeal larvae of

Para1ithodes camtschatica, in the southeastern Bering Sea in

Hokkaido Reg. Fish. Res. Lab. No. 24:163-170. (Fish. Res. Board

Sere No. 1191, 1968.)

king crab,

1960. Bull.

Can. Trans1.

Takeuchi, I. 1967. Food of king crab, Para1ithodes camtschatica, off the west

coast of the Kamchatka Peninsula, 1958-1964. Bull. Jpn. Sea Reg. Fish. Res.

Lab. 33:32-44. (Fish. Res. Board Can. Trans1. Sere No. 1194, 1968.)

33
Tarverdi eva , M.L 1976. Feeding of the Kamtchatka cr ab, Paralithodes

camtschatica and tanner crabst Chionoecetes bairdi and Chionoecetes opilio in the southern part of the Bering Sea. Soviet J. Mar. Biol. 2:34-39.

Tsalkina t A.V. 1969. Characteristics of the epifauna of the west Kamchatka

shelf (from "Problems of commercial hydr-obto loqy"}. Proc, All-Union Sci.

Res. Inst. Mar. Fish. Oceanogr. (VNIRO) Trudy 65:248-257. (Transl. Ser.

Fish. Res. Board Can. No. 1568 t 1970.)

Vinogradov t L.G. 1947.

Proc. All-Union Sci.

232.

The geographic distribution of the Kamchatka crab.

Res. Inst. Mar. Fish. Oceanogr. (VNIRO) Trudy 22:195-

Vinogradov t L.G. 1969. On the reproduction mechanism in the stocks of king

crab (Paralithodes camtschatica) in the Okhotsk Sea off western Kamchatka.

Proc. All-Union Sci. Res. Inst. Mar. Fish. Oceanogr. (VNIRO) Trudy 65:337-

344. (Transl. Ser. Fish. Res. Board Can. No. 1540 t 1969.)

Wallacet M.M. t C.J. Pertuit t and A.H. Hvatum. 1949. Contributions to the

biology of the king crab Paralithodes camtschatica (Tilesius). U.S. Fish

Wildl. Serv. t Fish. Leafl. 340:1-49.

Weber t D.O. 1967. Growth of immature king crab Paralithodes camtschatica

(Ft l est us) . Int. N. Pac , Fish. Comm. t Bull. 21:21-53.

Weber t D.O. and T. Miyahara. 1962. Growth of adult male king crab Paralithodes

camtschatica (Tilesius). U.S. Fish Wildl. Servo Fish. Bull. 62:53-75.

Wickham t D.E. t S.F. Blau t and A.M. Kuris. 1985. Preliminary report on egg

mortality in Alaskan king crabs caused by the egg predator Carcinonemertes.

Pages 365-370 in Proceedings of the international king crab symposium. Lowell WakefieldiFisheries Symposium Series t January 1985 t University of

Alaskat Alaska Sea Grant Rep. No. 85-12. 507 pp.

Wolotira t R.J. t Jr. t T.M. Sample t and M. Morin t Jr. 1977. Demersal fish and

shellfish resources of Norton Sound t the southeastern Chukchi Seat and

adjacent waters in the baseline year 1976. Northwest and Alaska Fish. Cent.

Process. Rep. NMFS/NWAFC t Seattle t Washington.

Wolotira t R.J. t Jr. t J.E.

distribution and abundance

Northwest and Alaska Fish.

Washington.

Munk t and J. H. Bowerman t Jr. 1984. Seasonal

of decapod larvae for the Kodiak Island region.

Cent. Process. Rep. 84-01. NMFS/NWAFC, Seattle,

34
S0271-IOI

REPORT DOCUMENTATION 11. 1I£l'OtlT NO.

Report 82(10.153): 2-

1. Recipient" Ace ••lloft No.

PAGE Biological

4. Tltl••nd lubtill. So 1I.1lO" 0.1.

Habitat Suitability Index Models: Red King Crab March 1988 .. ,._.) .. ,.rfonnl". O..."lullon lI.pt. "0.

S.C. Jewett and C.P. Onuf

t. ~rforml... O,.aftlzetlon Hame and Add,..,. 10. ''''ioctlT••kfWo,. U"lt "0.

U.S. Fish and Wildlife Service

Alaska Cooperative Fishery Research Unit 11. Com,••IICI or G.-mIGI "0.

138 Arctic Health Research Bldg., Uni versity of Alaska IC)

Fairbanks, AK 99775 12. $P'Onlorina O,••nlzatlon Hama and Add ..... IGI

U. Type of lI.po" & ,.,iocl Cowered

National Wetlands Research Center

Research and Development

Fish and Wildlife Service 14.

U.S. Department of the Interior

Washington, DC 20240

15. $upplam.ntary Nota.

I&. A~tr.ct (limit: 200 wards)

A review and synthesis of existing information were used to develop models for

evaluating habitat of different life stages of red king crab. The model is scaled

to produce an index between 0 (unsuitable habitat) and 1 (optimal habitat) in

Alaskan coastal waters, especially in the Gulf of Alaska and the southeastern

Bering Sea. Habitat suitability models are designed for use with the Habitat

Evaluation Procedures previously developed by the U.S. Fish and Wildlife Service.

Guidelines for model application and techniques for measuring model variables are

provided.

17. Document Analylil e. O.scriptors

Alaska

Crabs

Habitat

Mathemat i ca1 models

b. Identlfie,,/Open-[nded T."ml

Habitat Suitabi 1i ty Index

Impact assessment

Red King Crab

Paralithodes camtschatica •. CaSAli n.ldfGroup

lL A".i1ablllty Statement 1'. Security CI••, (Thil Report) 21. Ho. of , ••••

Unclassified 34

Unl imited -- 20. Sec:urity cra.1 (Thi, P•••) 22. 'rica

Unclassified IS•• AHSI-Z39.11)

u.s. GOVERNMENT PRINTING OFFICE: 1987-781-070/40006

OI"TIO"AL 'Olt.. 272 14-77)

l'orme,ly "TI5-JSI

Department 01 Commerce
TAKE PRIDE

in America "," "

• u.s. DEPARTMENT OF THE INTERIOR > _ ' • FISH AND WILDLIFE SERVICE

=.'"

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, ' ...•. -" ,.' '

As the Nation', principal conSflrvation agency , the Department of the Interior has ressonslbllity for most of our nationally owned public land. and natural re50Ufen. This Includ..

'ostennl the WIsest us.e of our land and water resourcn. Protectinl our fish and wildlife,

pr-.seJVml tn••nvlfonmenlal end cultuntl values 01 our national perk. and hIstorical placn.

and providin. for the enjoyment of life 1hmull'! outdoor recreation. T1'1. Department as -

MSseS our eneflY and mlner.1 resources and \IIfOrks to .Inure that thei, devel opment is in

tha bnt inte'etts of all our people. The Department .Iao has • INIjor respOnSIbility for

American Indian reservation communities and for peopM who Ii.... in island t.rritorin under

U.S. ~mln••t,..tIO" _