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Photo: CINMS. Photo: J. Maassen. Could spatial management of sea urchins increase fishery profits?. Sarah Teck, Nick Shears, Sarah Rathbone, Steve Gaines Department of Ecology, Evolution, and Marine Biology, University of California Santa Barbara. Background. red sea urchin fishery:

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could spatial management of sea urchins increase fishery profits

Photo: CINMS

Photo: J. Maassen

Could spatial management of sea urchins increase fishery profits?

Sarah Teck, Nick Shears, Sarah Rathbone, Steve Gaines

Department of Ecology, Evolution, and Marine Biology,

University of California Santa Barbara

background
Background
  • red sea urchin fishery:
    • California

~11.2 million lbs.

~$6.1 million

    • N. Channel Islands ~66%
    • Port of Santa Barbara ~52%
    • 90% western end

Santa Barbara

San Miguel

Santa Cruz

Santa Rosa

Anacapa

Image: www.incabrain.com

background1
Background
  • seasonal variability in gonad quality influences price
  • ($0.39/lb vs >$1.00/lb)
  • fishermen race to harvest year-round vs. waiting for optimal quality
  • (how much more $ would they make, if they waited?)
  • delaying harvest through spatial property rights,
  • TURF’s (Territorial Use Rights in Fisheries) 
  • fishermen’s profits
  • (also would save time, no need to survey area to fish during suboptimal conditions, just wait for optimal quality)
background2
Background
  • with fished species need to wait for
  • individuals and population growth
  • with urchins also need to wait for
  • seasonal gonad quality
  • first, we need to understand more detailed ecological information on temporal and spatial variability of gonad quality
background3
Background
  • with fished species need to wait for

individuals and population growth

  • with urchins also need to wait for
  • seasonal gonad quality
  • first, we need to understand more detailed ecological information on temporal and spatial variability of gonad quality
slide6

Channel Island field sampling

Santa Barbara

San Miguel

Santa Cruz

Santa Rosa

Anacapa

slide7

Red urchin gonad variability over space

gonad: somatic index (GSI)

Santa Barbara

San Miguel

Santa Cruz

Santa Rosa

Anacapa

red urchin gonad variability over time
Red urchin gonad variability over time

gonad: somatic index (GSI)

Oct

‘08

Dec

Feb

‘09

Mar

May

Jul

Aug

Oct

red urchin gonad variability over time1
Red urchin gonad variability over time

gonad: somatic index (GSI)

Oct

‘08

Dec

Feb

‘09

Mar

May

Jul

Aug

Oct

red urchin gonad variability over time2
Red urchin gonad variability over time

gonad: somatic index (GSI)

Oct

‘08

Dec

Feb

‘09

Mar

May

Jul

Aug

Oct

red urchin gonad variability over time3
Red urchin gonad variability over time

gonad: somatic index (GSI)

Oct

‘08

Dec

Feb

‘09

Mar

May

Jul

Aug

Oct

red urchin gonad variability over time4
Red urchin gonad variability over time

gonad: somatic index (GSI)

Oct

‘08

Dec

Feb

‘09

Mar

May

Jul

Aug

Oct

slide14

Red urchin landings 1985-2005

Purple urchin abundance 2007

purple sea urchin
purple sea urchin
  • purples compete with reds for kelp
  • not commercially harvested (smaller)
  • form persistent urchin barrens (mostly in the east)
  • long-term monitoring sites deforested by purples ~33% of the time—mostly in the east
slide17

Long-term (1985-2007) Variation in Kelp and Urchin

kelp

Density (m-2)

purple urchins

Density (m-2)

red urchins

Biomass (gm-2)

NPS—KFM data (eastern SCI and Anacapa Island)

slide18

Long-term (1985-2007) Variation in Kelp and Urchin

kelp

Density (m-2)

purple urchins

Density (m-2)

red urchins

Biomass (gm-2)

NPS—KFM data (eastern SCI and Anacapa Island)

slide19

Long-term (1985-2007) Variation in Kelp and Urchin

kelp

Density (m-2)

  • Red urchins have persistently higher biomass inside of the reserves.
  • Reproductive output is ~4 times higher in kelp forests versus urchin barrens

purple urchins

Density (m-2)

red urchins

Biomass (gm-2)

NPS—KFM data (eastern SCI and Anacapa Island)