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This study identified problems of the existing ecosystem-based fisheries assessment approach, and suggested new methods for scoring risk and for the estimation of fishery risk index. First, risk scores of zero to two for target and limit reference points for each indicator were replaced by those of zero to three, and the risk scores were calculated from new formulae which were developed in this study. Second, a new method for estimating fishery risk index (FRI) was developed in this study, considering the level of indicators. New method was applied to the Korean large purse seine fishery, large pair trawl fishery and drag net fishery. More precise and detailed risk scores were obtained from the new method, which can explain the risks by the wider range of both risk levels for `better than target` and `beyond limit`. The new method for estimating FRI could avoid the basic problem related with duplicated computations of fishery-level indicators, which improved the estimated FRI to be more accurate. Also, a method for estimating variance of FRI using the bootstrap was proposed in this study.

was target species for the trap fishery . For assessingindicators of four management objectives, that is the maintenance of sustainability , biodiversity , habitatquality and socio -economic benefits, indicators were selected considering the availability of data , whichwere 5 indicators for sustainability , 3 indicators for biodiversity , 4 indicators for habitat, 2 indicators forsocio -economic benefit. The Objective risk indices for sustainability and biodiversity of two fisheries wereestimated at yellow zone , medium risk level. The objective risk indices for habitat and socio -economicbenefit were estimated at green zone , safe level. The species risk indices (SRI) were estimated at yellowzone . The fishery risk indices (FRIs) were estimated at 1.143 and 1.400 for funnel net fishery and trapfishery , respectively . Finally the ecosystem risk index estimated at 1.184.Keywords: Jeonnam marine ranching , Ecosystem -based fisheries assessment, Risk index

The age and growth of flathead grey mullet , Mugil cephalus , were studied using samples collected from the coastal water of Yeosu from September 2009 to August 2010. Spawning season estimated from the gonadosometic index (GSI ) was from November to January . A method for increasing the readability of the otolith was described and criteria for the interpretation of otolith was provided . The annual ring was formed in September once a year . Annual ring in otolith for flathead grey mullet is validated for fish aged 1-8 using the marginal increment analysis . Using the sectioned otolith , between reader precision was 84%. Also , Within -reader agreement for sectioned otolith age readings was higher (reader 1〓84%, reader 2〓87%). The relationship between fork length and total weight was TW 〓0.022 FL 2.818 . The estimated von Bertalanffy growth parameters for the flathead grey mullet were L∞〓67.97 cm K〓0.164/ year and to〓－ 0.81 year .

Ecosystem-based fisheries management requires a holistic assessment of the status of fisheries by integrating fishery ecosystem indicators for management objectives. In this study four objectives were identified such as the maintenance of the sustainability, biodiversity and habitat quality and socio-economic benefits. The ecosystem-based fisheries assessment (EBFA) model to assess fisheries and their resources at the ecosystem level developed for Korean fisheries (Zhang et al., 2009) has a number of indicators for three management objectives. However, it was found that there were some overlapping components among indicators and that there were difficulties in assessing some indicators in the EBFA model. This study identified problems of the approach and suggested more pragmatic and simpler indicators. It also presented alternative reference points to assess indicators and discussed issues associated with the application of the EBFA model to a marine ranching ecosystem. In this study a total of 24 indicators were used for the assessment which included 4 socio-economic indicators. New indicators and reference points were demonstrated by applying it to the Uljin marine ranch.

A self-regulatory community fisheries management program in Korea is designed to enhance fisheriesresources, to protect fishing grounds of self-regulatory communities, and to manage their fisheries resourcesby their own regulations and knowledge. This study explored an applicable ecosystem-based managementplan based on the scientific investigation and analysis. This study suggested objectives, indicators andreference points of the ecosystem-based resource management system which are applicable to self-regulatory community fisheries. The objectives of the management system are to maintain sustainablefisheries production, to maintain optimum fishing intensity, to reduce by-catch, to conserve spawningground and habitat, to maintain optimum habitat environment, to increase/maintain abundance of preyspecies, to increase/maintain stock biomass, and to conduct stock enhancement on the basis of scientificassessment. The improved methods for the assessment and management are introduced by demonstrating aself-regulatory fishery which targets on hen clam in Dong-li fishing village in Busan.Key words : Ecosystem-based management, Self-regulatory community fisheries, Objectives, Indicator,Reference point

This study was performed to estimate biomass and to provide management plan through population ecological characteristics, including growth parameters, survival rate, instantaneous coefficient of natural and fishing mortalities, and age at first capture of hen clam, Mactra chinensis, in the Dong-li self-regulatory community of Busan. The von Bertalanffy growth parameters estimated from a non-linear regression were SH∞ 86.24mm, K 0.12/year, and 1.37year. Survival rate(s) of the hen clam was 0.515. The instantaneous coefficients of natural mortality(M) was estimated to be 0.232/year and fishing mortality(F) 0.432/year for hen clam. The current biomass of the hen clam in the study area was estimated to be 713mt and the acceptable biological catch(ABC) was estimated under various harvest strategies based on F0.1 and F40%.