Modeling the Efficacy of Three Types of Artificial Timber Reefs in Mitsu Bay, Japan

Jamaluddin Fitrah Alam,Tetsuya Umino,Shinya Nakahara,Tamiji Yamamoto,Kiyonori Hiraoka

doi:10.3390/w12072013

Abstract

With the aim of simultaneously improving fishery production and utilizing forestry and oyster fishery wastes, three types of artificial timber reefs (ATRs)—constructed from simple timbers, timbers with oyster shells from local oyster farms, and timbers with leaves/branches from forest thinning—were deployed in Mitsu Bay, Japan. We developed a food web model to investigate the relative efficacies of these ATR types compared with the bare, sandy seafloor. The model described the material flow through the food webs formed in each ATR type and their potential to increase fisheries production. The model outputs were validated with observational data over three years. The model fit the observed biomass of both prey animals and fish predators. The simulation results highlighted that ATRs, particularly those with additional materials, had two to three times higher feeding flow than the sandy seafloor and resulted in increased fish biomass. Fish catch doubled in the ATR areas compared to the bare seafloor. Aside from providing a feeding ground, the complexity of the ATRs with additional materials likely acts to provide shelter for juvenile fish. ATR deployment using by-products such as those mentioned above may not only enhance fish stock but also help foster the establishment of a recycling-oriented society.

Highlights

Artificial reefs (ARs) are human-made structures deployed in the aquatic ecosystem for various services and benefits
The calculations from the numerical model of the attached and benthic animal biomass showed good and satisfactory fits to all observed values; the percent bias (PBIAS) values were in the 25–70% range for all, except for bivalves (BIV), errant worm (EWO), caprellid (CAP), and other amphipods (OAM) in the artificial timber reefs with leaves and branches (ATRsLB) (Table S1)
caprellid biomass (CAP), shrimp biomass (SHR), BIV, errant worm biomass (EWO), and sedentary worm biomass (SWO) were significantly higher in artificial timber reefs with oyster shells (ATRsOS) and ATRsLB

Summary

Introduction

Artificial reefs (ARs) are human-made structures deployed in the aquatic ecosystem for various services and benefits. The deployment of ARs is believed to benefit fishery yield by providing a habitat for fish and their feeds [1,2]. The type of structures and materials used for the construction of ARs is key for meeting the expected goals. The materials used for AR construction vary around the world, ranging from either natural materials such as rocks, shells, and wood or artificial materials such as concrete, fiberglass, tires, vessels, and vehicles [3]. In Japan, fishery production has been decreasing over the past few decades [4]. The current estimated domestic fishery production is approximately 60% and the remaining 40% is imported

Objectives

Methods

Results

Conclusion