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Female reproductive potential of eastern Bering Sea snow crab (Chionoecetes opilio) Laura M. Slater 1,3 , Joel B. Webb 2 , Gordon Kruse 3 , Franz J. Mueter 3 , Bernard Sainte-Marie 4 , Ginny L. Eckert 3 , and Douglas Pengilly 1 1 Alaska Department of Fish and Game, Commercial Fisheries Division, Kodiak, AK, USA. 2 Alaska Department of Fish and Game, Commercial Fisheries Division, Juneau, AK, USA. 3 University of Alaska Fairbanks, College of Fisheries and Ocean Sciences, Juneau, AK, USA. 4 Department of Fisheries and Oceans, Maurice Lamontagne Institute, Mont-Joli, QC, Canada.

Female reproductive potential of eastern Bering Sea snow ...Ashton Photography . Goals • Develop an index of female reproductive potential that reflects stock mating dynamics •

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Page 1: Female reproductive potential of eastern Bering Sea snow ...Ashton Photography . Goals • Develop an index of female reproductive potential that reflects stock mating dynamics •

Female reproductive potential of eastern Bering

Sea snow crab (Chionoecetes opilio)

Laura M. Slater1,3, Joel B. Webb2, Gordon Kruse3, Franz J. Mueter3, Bernard

Sainte-Marie4, Ginny L. Eckert3, and Douglas Pengilly1

1Alaska Department of Fish and Game, Commercial Fisheries Division, Kodiak, AK, USA. 2Alaska Department of Fish and Game, Commercial Fisheries Division, Juneau, AK, USA.

3University of Alaska Fairbanks, College of Fisheries and Ocean Sciences, Juneau, AK, USA. 4Department of Fisheries and Oceans, Maurice Lamontagne Institute, Mont-Joli, QC, Canada.

Page 2: Female reproductive potential of eastern Bering Sea snow ...Ashton Photography . Goals • Develop an index of female reproductive potential that reflects stock mating dynamics •

Motivation

• EBS snow crab is a

federally managed stock.

• FMP approved in 1989.

• The FMP establishes a

State/Federal

cooperative

management regime that

defers crab management

to the State of Alaska

with Federal oversight.

Page 3: Female reproductive potential of eastern Bering Sea snow ...Ashton Photography . Goals • Develop an index of female reproductive potential that reflects stock mating dynamics •

Motivation

Figure modified from Pengilly et al. (2014).

Data compiled from NMFS Fisheries Statistics Division:

www.st.nmfs.noaa.gov/st1/commercial/landings/gc_runc.html.

Commercial

Harvest

EBS snow

crab have

contributed ~¼

of the biomass

of crabs

commercially

harvested in

the U.S. over

the past three

decades

Page 4: Female reproductive potential of eastern Bering Sea snow ...Ashton Photography . Goals • Develop an index of female reproductive potential that reflects stock mating dynamics •

Motivation

How does large-male exploitation influence

female reproductive potential and stock productivity?

Mature male biomass

used as an index of

reproductive potential

in stock assessment

Ashton Photography

www.lastfrontier.org

Page 5: Female reproductive potential of eastern Bering Sea snow ...Ashton Photography . Goals • Develop an index of female reproductive potential that reflects stock mating dynamics •

Goals

• Develop an index of female reproductive potential

that reflects stock mating dynamics

• Analyze spatiotemporal trends in female sperm

reserves to inform functional relationships among

female reproductive potential, maternal

characteristics, and the availability of male mates

• Assess the impact of the fishery’s harvest of only

large males on the reproductive output by females

• Compare new indices with the biomass proxy for

stock productive capacity currently used in

management

Page 6: Female reproductive potential of eastern Bering Sea snow ...Ashton Photography . Goals • Develop an index of female reproductive potential that reflects stock mating dynamics •

Approach

Evaluate Fecundity

• Factors that effect

variability in egg

production

• Clutch fullness index

over survey time series

Evaluate Female

Sperm Reserves

• Male availably for

mating and direct

measure of contribution

to female reproductive

success

• Spatiotemporal

variability

Page 7: Female reproductive potential of eastern Bering Sea snow ...Ashton Photography . Goals • Develop an index of female reproductive potential that reflects stock mating dynamics •

Approach

Shell

Condition

Newshell

(SC2)

Oldshell

(SC3)

Very Oldshell

(SC4-5)

Reproductive

status Immature Primiparous

Multiparous

(Primiparous) Multiparous

Approximate

years post-

maturity

≤~ 1yr. ~2-4 yr. 4+ yr.

Female Reproductive Stage

Page 8: Female reproductive potential of eastern Bering Sea snow ...Ashton Photography . Goals • Develop an index of female reproductive potential that reflects stock mating dynamics •

Approach

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Depth (m)

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Study Area: Annual NOAA AFSC EBS shelf trawl survey

Page 9: Female reproductive potential of eastern Bering Sea snow ...Ashton Photography . Goals • Develop an index of female reproductive potential that reflects stock mating dynamics •

Approach

• Sperm

• Eggs

• Maternal characteristics and condition

Sample Processing: Dissect Crabs

Page 10: Female reproductive potential of eastern Bering Sea snow ...Ashton Photography . Goals • Develop an index of female reproductive potential that reflects stock mating dynamics •

Approach

Sample Processing: Sperm Storage

• Wet weight and counts

2nd count

Page 11: Female reproductive potential of eastern Bering Sea snow ...Ashton Photography . Goals • Develop an index of female reproductive potential that reflects stock mating dynamics •

Results

In Press. Canadian Journal of Fisheries and Aquatic Sciences.

Page 12: Female reproductive potential of eastern Bering Sea snow ...Ashton Photography . Goals • Develop an index of female reproductive potential that reflects stock mating dynamics •

Results

Clutch Fullness Index

Page 13: Female reproductive potential of eastern Bering Sea snow ...Ashton Photography . Goals • Develop an index of female reproductive potential that reflects stock mating dynamics •

Results

Robust size-fecundity relationship by clutch fullness

0 1 2 3 4 5 6 7 8 9

Series1

Series2

Series3

Series4

Series5

0

25,000

50,000

75,000

100,000

40 55 70 85

Fec

un

dit

y

Carapace Width (mm)

CFI 2

CFI 3

CFI 4

CFI 5

CFI 6

Linear mixed model, R2=0.80

Page 14: Female reproductive potential of eastern Bering Sea snow ...Ashton Photography . Goals • Develop an index of female reproductive potential that reflects stock mating dynamics •

Results

SC2 SC3

SC4 SC5

Increased variability and decreased output over

reproductive stage (age)

Page 15: Female reproductive potential of eastern Bering Sea snow ...Ashton Photography . Goals • Develop an index of female reproductive potential that reflects stock mating dynamics •

Results

Indices of Reproductive Potential

Page 16: Female reproductive potential of eastern Bering Sea snow ...Ashton Photography . Goals • Develop an index of female reproductive potential that reflects stock mating dynamics •

Conclusions

Egg Production

• clutch fullness index is a robust index of

egg production

• Demography (age & proportion abundance

by age) impacts population egg output

• Egg production index is proportional to

mature female abundance

• Proportion of population on biennial cycle

important but difficult to estimate

Page 17: Female reproductive potential of eastern Bering Sea snow ...Ashton Photography . Goals • Develop an index of female reproductive potential that reflects stock mating dynamics •

Results

2010. Biology and Management of Exploited Crab Populations under

Climate Change.

Page 18: Female reproductive potential of eastern Bering Sea snow ...Ashton Photography . Goals • Develop an index of female reproductive potential that reflects stock mating dynamics •

Results

• Most (92% of

3,781) snow

crab examined

had clutches

with mostly

viable eggs

• Restricted to

eggs with

noticeable

embryonic

development

Page 19: Female reproductive potential of eastern Bering Sea snow ...Ashton Photography . Goals • Develop an index of female reproductive potential that reflects stock mating dynamics •

Results

• Scale established for Atlantic Ocean snow crab

• Low SL where most of population is distributed

• Similar trends by reproductive stage

Primiparous Multiparous

Page 20: Female reproductive potential of eastern Bering Sea snow ...Ashton Photography . Goals • Develop an index of female reproductive potential that reflects stock mating dynamics •

Results

Size declines with latitude across all years

Page 21: Female reproductive potential of eastern Bering Sea snow ...Ashton Photography . Goals • Develop an index of female reproductive potential that reflects stock mating dynamics •

Results

SL also declines with latitude across all years

Page 22: Female reproductive potential of eastern Bering Sea snow ...Ashton Photography . Goals • Develop an index of female reproductive potential that reflects stock mating dynamics •

Results

SL increases with female size

Page 23: Female reproductive potential of eastern Bering Sea snow ...Ashton Photography . Goals • Develop an index of female reproductive potential that reflects stock mating dynamics •

Results

However, when examined at a station level

2012

Page 24: Female reproductive potential of eastern Bering Sea snow ...Ashton Photography . Goals • Develop an index of female reproductive potential that reflects stock mating dynamics •

Results

However, when examined at a station level

2013

Page 25: Female reproductive potential of eastern Bering Sea snow ...Ashton Photography . Goals • Develop an index of female reproductive potential that reflects stock mating dynamics •

Conclusions

Sperm Reserves

• no evidence of current sperm limitation

• re-mating is necessary and occurs

frequently

• lack of buffer against sperm limitation

• persistent spatial trends

Page 26: Female reproductive potential of eastern Bering Sea snow ...Ashton Photography . Goals • Develop an index of female reproductive potential that reflects stock mating dynamics •

Future Directions

Needs and New Opportunities

• Biennial reproduction – difficult to model,

paucity of empirical data

• Relationship with sex ratio (quantity and

quality of males)

• Relationship with temperature

• Genetics of paternity

Page 27: Female reproductive potential of eastern Bering Sea snow ...Ashton Photography . Goals • Develop an index of female reproductive potential that reflects stock mating dynamics •

Many Helping Hands

Pilot Study • Kirsten MacTavish (formerly ADF&G, now IPHC)

Project Management • ADF&G: Nat Nichols, Natura Richardson

Sample Collection – NOAA EBS Survey • ADF&G, NOAA, UAS survey participants, especially: Meg

Inokuma, Mike Knutson, Natura Richardson

Logistics & Sample Transport • ADF&G Kodiak and Dutch Harbor staff, NOAA Kodiak Lab staff,

UniSea

Live Crab Stewardship & Sample Processing • ADF&G in Kodiak and Juneau, especially: Kayla Bevaart, Jassalyn

Bradbury, Leslie Curran, Tara Fritzinger, Meg Inokuma, Sarah

Johnson, Thomas Kinsley, Mike Knutson, Nina Leacock, Natura

Richardson, Andrew Olsen

Page 28: Female reproductive potential of eastern Bering Sea snow ...Ashton Photography . Goals • Develop an index of female reproductive potential that reflects stock mating dynamics •

Funding

• ADF&G, including Bristol Bay Red King Crab Test Fishery

• National Oceanographic and Atmospheric Administration Grants

• North Pacific Research Board (Project #714)

Page 29: Female reproductive potential of eastern Bering Sea snow ...Ashton Photography . Goals • Develop an index of female reproductive potential that reflects stock mating dynamics •

Any Questions?

[email protected]