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Spatial and temporal variations in abundance and distribution of juvenile and adult jackass morwong, Nemadactylus macropterus, in south-eastern Tasmania

journal contribution
posted on 2023-05-16, 13:19 authored by Alan JordanAlan Jordan
Depth-stratified random demersal trawl surveys of the shelf of southern and eastern Tasmania from summer 1993 to summer 1995 showed seasonal variations in abundance of N. macropterus in all depth strata, although the trend varied between years, with abundance peaking in summer 1993 and winter 1994. This variation is attributed to the seasonal movement of fish from south-eastern Tasmanian shelf waters, although some seasonal change in size composition is also evident. Catch rates were highest on the outer shelf and lowest on the inner shelf, reflecting the distinct size-structuring, with juveniles concentrated on the inner and mid shelf and mature fish on the outer shelf. Size compositions differed among shelf regions, with few mature fish on the mid shelf of Storm Bay compared with the same stratum on the east coast, indicating that the bay is primarily a nursery area for the species. Settlement from the pelagic post-larval phase occurred in spring and early summer at 7-9 cm, with evidence of movement between inner- and mid-shelf strata by autumn. Abundance of 0+ fish was highest in 1993 and 1994 and a considerable decrease in the abundance in both regions in 1995. The influences of local hydrography and the large size at settlement are discussed.

History

Publication title

Marine and Freshwater Research

Volume

52

Issue

4

Pagination

661-70

ISSN

1323-1650

Department/School

Institute for Marine and Antarctic Studies

Publisher

CSIRO Publishing

Place of publication

Victoria, Australia

Repository Status

  • Restricted

Socio-economic Objectives

Fisheries - wild caught not elsewhere classified

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