Quantitative indicators to track changes on fish abundance based on - - PowerPoint PPT Presentation

Quantitative indicators to track changes on fish abundance based

• n fishers’ knowledge in the Tapajos River, Brazilian Amazon

Renato A. M. Silvano

• Dep. Ecology

Universidade Federal do Rio Grande do Sul

Photo: Pedro Peixoto

Research Project: Linking sustainability of small-scale fisheries, fishers’ knowledge, conservation and co-management of biodiversity in large rivers of the Brazilian Amazon

PEER Cycle 4 Grant Award Number: AID-OAA-A-11

Mekong Mackenzie Tapajos

Tapajós River ➢ 8 fishing communities, 4 inside X 4 outside (red squares) Extractive Reserve (RESEX): comparison

Communities River Lake

RESEX Tapajos-Arapiuns 1998

Main goal: 5 quantitative indicators to track changes on fish availability from fishers’ knowledge (interviews) 1) Fish size: indicated in a tape 2)Temporal trends on fish abundance: increased, same or decreased ✓ 3) Composition of catches: species of fish cited (already presented) 4) Biomass of fish caught (kg) 5) Catch per unit of effort (CPUE) of fish caught: kg/h x n of fishers

✓ Interviews with fishers: standard questionnaire with 31 questions addresing fishing practices, socioeconomic issues, local knowledge, management ✓ Snow-ball sampling: 161 fishers interviewed, 10 to 20 fishers in each studied community Methods

Questions about fish: 1) Which are the most caught fish species (list 5)? 2) Which is the average size of these fish (show in a metric tape)? 3) Do you think that the abundance of these fish has increased, decreased or remained the same over the las 20 years? 4) How much fish (kg) do you regularly catch? 5) How many hours you take to cath this amount of fish and with how many people? 2006 2016 1996

RESEX Tapajós-Arapiuns

Past (20 years ago) Actual

1) Fish size: citations of size estimates for 12 commercial fish species (or groups of species) in both time periods

Aracu Caratinga Dourada Filhote Jaraqui Mapara Pacu Pescada Pirarucu Surubim Tambaqui Tucunare

Fish 50 100 150 200 250 300 350 F i s h s i z e ( c m ) Past (20 years) Actual PERIOD

Outside RESEX Region

30 60 90 120 150 180 210 240 270 300

F i s h s i z e ( c m ) 20 years ago Actual Period

Larger fish in the past, no difference between RESEX and outside

A r a c u B a r a r u r á B

• c

ó B r a n q u i n h a C a r a t i n g a C h a p e r e m a C h a r u t

• D
• u

r a d a F i l h

• t

e F u r a

• c

a l ç a J a r a q u i M a p a r á P a c u P e s c a d a P i a u P i r a r u c u S a r d a S u r u b i m T a m b a q u i T u c u n a r é

Fish species

• 1.0
• 0.6
• 0.2

0.2 0.6 1.0 A b u n d a n c e t r e n d

• utside

RESEX REGION

2) Comparison of abundancetrends, for each fish species: Increased= +1, Same = 0, Decreased = -1 (X proportion of fishers) All fish decreasedin abundance, except a small, less valuablefish insideRESEX

4) Biomass of fish caught (kg): more fish in the past, no difference between RESEX and outside (OUT X)

OUT X RESEX Region 1 2 3 4 Log10 (Fish Biomass kg) 20 years ago Actual Period

5) CPUE: higher CPUE in the past, no difference between RESEX and outside (“Fora”)

Fora RESEX Region 1 2 3 L

• g

1 C P U E f i s h 20 years ago Actual Period

Indicators Temporal change? Influence of RESEX? Fish composition of catches No No Temporal abundance trends Yes No Fish size Yes No Biomass of fish caught Yes No CPUE of fish caught Yes No

Biomass, CPUE and temporal trends indicated same patterns Temporal change, few effects of RESEX

We made 16 meetings with fishers in all fishing communities to discuss some of the results of the research.

Photo: Daiana Scneider

Acknowledgments ➢ To fishers for their cooperation ➢ To USAID for funding the research ➢ The research team ➢ To Tracking Change Project and SSHRCC ➢ To you by your attention

Questions??