KELP-SEA URCHIN-FISHERMEN DYNAMICS: IMPLICATIONS FOR SMALL-SCALE FISHERIES MANAGEMENT

Nicolas GutierrezSAFS - UW

R Hilborn, AE Punt, LW Botsford, D Armstrong, D Beauchamp

I. A spatially-explicit individual-based model of sea urchin, kelp and fishermen

II. Alternative approaches for sea urchin stock assessment

- Gutiérrez et al. Developing a Bayesian stock assessment framework and decision analysis for the red sea urchin fishery in Baja California, Mexico (Submitted N. Am. J. Fish. Manag.)

III. Exploring dedicated access management strategies for sedentary small-scale fisheries

- Fishing for uni: potential benefits of cooperative harvesting

Thesis Sections

Background & Motivation 

• Roe fishery, with marked spatio-temporal patterns in gonad quality/yield (depending on food availability)

• SDWA and the fishing industry concerned about sustainability and economic viability. Optimize harvest flexibility and quality by:

- getting biological information to better manage the fishery (BE program)

- developing a community-based management strategy

• Fishing for uni: Selective harvesting of “well fed urchins”, by fishing those areas where the gonad yield is at its peak

Fishing for uni: potential benefits of cooperative harvesting

Approach

5 areas with same number of urchins (B0 = 20,000)

1. Competitive fishery: each diver go to the area that produced the best return (as total uni production: Y = gonad yield x abundance)

2. Cooperative managed fishery: each diver is directed to fish each area at/around its seasonal peak

a. Constant recruitment (legal/mature):

b. Seasonal/pulse recruitment:

 

Fishing for uni: potential benefits of cooperative harvesting

Time

Re

cru

itsR

ecru

its

Fishing for uni: potential benefits of cooperative harvesting

DATA: Spatio-temporal variations in gonad yield (%)

4.0

5.0

6.0

7.0

8.0

9.0

Jan-05

Feb-05

Mar-05

Apr-05

May-05

Jul-05 Aug-05

Sep-05

Oct-05

Nov-05

Time (months)

4.00

5.00

6.00

7.00

8.00

9.00

1 2 3 4 5 6 7 8 9 10 11 12

Time (months)

Gonad Y

ield

(%

)

12345

Area 3

a

b

Preliminary results 

Fishing for uni: potential benefits of cooperative harvesting

Catch (lbs)

Revenue (US$)

Catch 22,449 25,943 13%

Revenue 18,821 23,272 19%

Catch 20,931 21,355 2%

Revenue 17,370 19,665 12%

Change

Constant

Seasonal

Open Access (Competitive) Dedicated Access (Cooperative)

Management strategyRecruitment Indicator

Competitive Cooperative

Constant recruitment Seasonal recruitment

Competitive Cooperative Competitive Cooperative

Next steps

• Increase spatial resolution of data set on gonad yield, abundance, etc

• Density-dependence recruitment

• Market considerations (e.g. price depending on catches 2 weeks earlier)

• Gonad Quality threshold (e.g. > 5.2 % ~ 0.75 $ per lbs)

• Depletion levels (e.g. B=0.4•B0)

• Include processing costs for “bad” urchins

 

Fishing for uni: potential benefits of cooperative harvesting