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COMPARATIVE STUDY OF FISH ASSEMBLAGES ON ARTIFICIAL AND NATURAL REEFS

Introduction

In 2000 three artificial reefs were installed on the damaged reef in front of the Bajo village of Sampella. Since this time the colonisation of these artificial reefs has been monitored. The artificial reefs are constructed of tires. Five units of nine tires are used for each artificial reef. Metal ties are used to hold the tires in place. These artificial reefs are approximately 2.5m X 5m, and less than 1m tall.

Aims

• To understand the fish community assemblages on artificial reefs and compare them to an adjacent degraded reef. 

•             To understand changes in the fish community assemblages during the day 

•             To understand changes in the fish community assemblages over the last three years. 

• To understand how the fish community assemblages compare to the fish species caught by the artisanal fisheries at Sampella.

Objectives

• To determine fish assemblages at different times of the day

• To determine fish assemblages on the artificial reef, the adjacent degraded reef and the pristine reef site.

• To examine historical records of these sites over the last two years and compare to results from this year.

• To interview local fishermen on the type of fishing practices and the area fished  and record species abundance, size and weight of the fish caught by the local fishermen at Sampela.

• To determine target species, by-catch and catch per unit effort. Determine fishing pressure on reefs surrounding the sample sites.

Methods

SCUBA equipment was used to make visual counts of the fish assemblages along a 50m X 5m X 5m transect at both the pristine and the degraded reef. Counts were taken over a twenty-minute period. For both of the natural reefs transects were made along the reef slope, the reef crest and the reef flat. Three replicates were made for each area of the reef for both a.m. and p.m. counts. The entire fish community associated with the artificial reefs was recorded.

Preliminary results 

Artificial reef 1:

Total species recorded: 27 spp

Average species recorded per count:18

Average number of individual fish: 237

Artificial reef 2:

Total species recorded: 32 spp

Average species recorded per count:19

Average number of individual fish: 578 

This artificial reef had the largest diversity of species and abundance. There was also a very high percentage of juvenile fish.

Artificial reef 3:

Total species recorded: 16 spp

Average species recorded per count: 9

Average number of individual fish: 96

Kaledupa pristine reef:

Average species recorded: 40

Sampela degraded reef:

Average species recorded: 38

Fish species associated to the artificial reefs: 

Dissemination of results

A final year dissertation report entitled A comparative study of fish assemblages on artificial and natural reefs will be completed by Lee Dunnett, University of Essex by May 2003.