PVOA Sunny Rice, Marine Advisory Agent, UAF Outline 1) Background - - PowerPoint PPT Presentation

▶
pvoa
SMART_READER_LITE
LIVE PREVIEW

PVOA Sunny Rice, Marine Advisory Agent, UAF Outline 1) Background - - PowerPoint PPT Presentation

Nov 07, 2022 504 likes •874 views

Recolonization, prey selection and resource competition by sea otters, Enhydra lutris , in southern southeast Alaska. Zac Hoyt, PhD student, UAF Verena Gill, Wildlife Biologist, USFWS Ginny Eckert, Professor, UAF PVOA Sunny Rice, Marine

slide-1
SLIDE 1

Recolonization, prey selection and resource competition by sea otters, Enhydra lutris, in southern southeast Alaska.

Zac Hoyt, PhD student, UAF Verena Gill, Wildlife Biologist, USFWS Ginny Eckert, Professor, UAF Sunny Rice, Marine Advisory Agent, UAF

PVOA

slide-2
SLIDE 2

1) Background – Sea otter biology A)Historic and current distribution of sea otter in the N Pacific, AK, SE AK, and finally SSE AK. B)Current distribution and growth of SSE AK otter pop. C)Resource competition in SE AK

Outline

slide-3
SLIDE 3

1) Background – Sea otter biology A)Historic and current distribution of sea otter in the N Pacific, AK, SE AK, and finally SSE AK. B)Current distribution and growth of SSE AK otter pop. C)Resource competition in SE AK 2) Foraging A)Calculate proportion of sea otter diet of commercially important macro invertebrates in SSE AK.

Outline

slide-4
SLIDE 4

1) Background – Sea otter biology A)Historic and current distribution of sea otter in the N Pacific, AK, SE AK, and finally SSE AK. B)Current distribution and growth of SSE AK otter pop. C)Resource competition in SE AK 2) Foraging A)Calculate proportion of sea otter diet of commercially important macro invertebrates in SSE AK. B) Differences in sea otter diet on a spatial scale relating to current sea otter distribution.

Outline

slide-5
SLIDE 5

Sea otters have a high metabolism

The only marine mammals without blubber

slide-6
SLIDE 6

Sea otter predators

Orcas Sharks Eagles

slide-7
SLIDE 7

Only 1 pup/year. Rare twinning.

slide-8
SLIDE 8

Population of sea otters ranged from 200,000 – 300,000 pre fur trade

slide-9
SLIDE 9

1000 -2000 sea otters in 1911

slide-10
SLIDE 10

Present population 85,000 individuals

Current estimate 82,350-95,000 sea otters

slide-11
SLIDE 11

Alaska (73,000+) in 3 stocks

USFWS 2009

slide-12
SLIDE 12

Translocation Sites

Cape Spencer Yakobi Island Khaz Bay Biorka Island Maurelle Islands Barrier Islands 55 51

slide-13
SLIDE 13

1960’s Release

Esslinger and Bodkin 2009

Southern portion (2003) estimated at 5,845 otters SE = 821 SE AK

2003 Population

Maurelle Islands 51 otters Barrier Islands 55 otters

slide-14
SLIDE 14

Survey completed

July / Aug. for SSE AK

Aerial Survey method

Systematic transects, stratified design, with a calculated site ability factor

slide-15
SLIDE 15
slide-16
SLIDE 16

Results 2010

Growth rate =

13% annually

Abundance estimate =

In review

slide-17
SLIDE 17

5,845 otters in 2003 2010 13% annual increase since 2003

slide-18
SLIDE 18

Sea otter harvest levels in SE AK 1989-2010

*

slide-19
SLIDE 19

Resource Conflicts

slide-20
SLIDE 20

Fisheries affected in southern SE AK - value $16 million dollar (2008 -09) Dungeness Crab, Metacarcinus magister (formerly Cancer magister) Red Sea Urchin, Strongylocentrotus franciscanus California Sea Cucumber, Parastichopus californicus Geoduck Clam, Panopea abrupta

slide-21
SLIDE 21

YEAR

Fisheries Interactions

Sea otter abundance

slide-22
SLIDE 22

Foraging

data collection

slide-23
SLIDE 23

The sea otter diet is extremely diverse

Specialists and generalists. High metabolic rate so can eat up to 23% of body weight

slide-24
SLIDE 24

Forage in shallow water (0-100 m)

slide-25
SLIDE 25

Foraging

50 mm 1.5 paw Telmessus cheiragonus Coded = TEC – 2b

slide-26
SLIDE 26

2010 Field Work

slide-27
SLIDE 27

116 bouts recorded 1500 dives recorded 1332 successful

Otter foraging success

Results

slide-28
SLIDE 28

Diet composition by taxonomic group

slide-29
SLIDE 29

Red king crab, Paralithodes camtschaticus Pinto Abalone, Haliotis kamtschatkana Pandalus spp. - 2 % Tanner Crab, Chionoecetes bairdi - < 1%

Other commercially important species

slide-30
SLIDE 30

Commercial Component of Sea Otter Diet

108 bouts, 1332 dives Proportion of observed diet

slide-31
SLIDE 31

Spatial

differences in diet

1)Colonization history 2)Ho: Commercially important component of diet does not differ by otter colonization history

slide-32
SLIDE 32

Otters present before 2003 Otters present since 2003 Proportion of observed diet

z= -1.85, p=0.643 z= -3.114, p=0.0018 z= 5.121, p<0.0002

slide-33
SLIDE 33

Observed proportion of diet

z= 5.121, p<0.0002 z= 5.87, p<0.0002

No statistical power Proportion of observed diet

slide-34
SLIDE 34

Conclusion

  • Results confirm what we have been hearing

anecdotally from the commercial fleet.

  • Otters are having a significantly greater effect on

commercial macro invertebrates on the frontal boundaries of their current distribution especially relating to California Sea Cucumbers and Dungeness Crab.

  • More foraging data is needed from the region to

address conflict of the other commercially important species.

slide-35
SLIDE 35

What’s next

  • Continue forage

sampling in 2011

  • Caloric/ biomass

scale

  • Fisheries assessment

analysis, depletion rates, spatial scale and economic impacts

  • NPRB project

Goal: Examine interactions between sea otter population & prey, small- scale distribution, movement, & prey selection

  • n the recolonizing front of

the SSE AK population

slide-36
SLIDE 36

PERMITS : MMPA permit #041309 IACUC 164017-1

Special Thanks

Icicle Seafood's Kake Tribal USFS - Petersburg Ranger District Bonnie Greenwood Tory Wilson Marlene Wagner Crew of the F/V’s: Kuprenof Kamalar Westerly Deco Bay