Developing Assessments and Performance Indicators for a Small-Scale Temperate Reef Fish Fishery

Developing Assessments and Performance Indicators for a Small-Scale Temperate Reef Fish Fishery

Philippe E. Ziegler, Jeremy M. Lyle, Malcolm Haddon, and Paul Burch

Developing Assessments and Performance Indicators for a Small-Scale Temperate Reef Fish FisheryThis is part of Fisheries Assessment and Management in Data-Limited Situations
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Description

In Australia, the development of live fish markets in the early 1990s created strong demand for temperate reef fish species, particularly banded morwong (Cheilodactylus spectabilis). The fishery expanded rapidly over a very short period but has subsequently undergone a marked decline. Several management controls have been progressively introduced, including size limits, seasonal closures, and limited entry. Only simple performance indicators based on catch and catch rate trends have been utilized to monitor stocks.

Banded morwong are sedentary and appear to have a depth-structured sex and size distribution. They are long-lived (>80 years), and growth rates and maximum sizes are distinctly different for males and females. These life-history characteristics and the likely population structuring at small spatial scales have marked consequences for stock assessment.

A variety of simple assessment approaches, including catch rate standardization, yield-per-recruit and spawning biomass-per recruit analyses, catch curve analysis, and biological indicators (median size and age, sex ratio) have been examined. These methods proved inconclusive in indicating whether current fishing levels are sustainable, or based on continued reduction of accumulated biomass and/or serial depletion of spatially structured populations. General uncertainty regarding data quality from the commercial fishery and spatial representation of biological data within the populations are of concern.

Because data intensive assessment techniques cannot be justified for this small-scale fishery, we propose the development of an operating model that can be used to evaluate whether simple biological and/or fishery indicators can assist performance monitoring and address issues of sustainability.

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