Deakin University
Browse

File(s) under embargo

Temporal variability of pelagic fish assemblages around fish aggregation devices: Biological and physical influences

Version 2 2024-06-03, 01:47
Version 1 2024-01-17, 02:01
journal contribution
posted on 2024-06-03, 01:47 authored by Tim DempsterTim Dempster
Pelagic fishes were counted around four fish aggregation devices (FADs) moored between 3 and 10 km offshore on the continental shelf off Sydney, Australia. Visual counts were made at FADs on 81 days periodically from April 1999 to April 2002. Surface water temperature and current speed were also measured at the FADs. Assemblages of fishes at FADs followed a seasonal pattern, however, biological and physical variables influenced seasonal structure greatly. Abundances at FADs were greatest in spring due to the appearance of large schools (100s to 1000s) of juvenile Trachurus sp. In contrast, diversity was far greater in summer and autumn, principally due to the appearance of schools (10s to 100s) of juvenile Coryphaena hippurus(Coryphaenidae), and other warm water species from January to May when water temperatures were >20° C. Short‐term variability differed among species; C. hippurus fluctuated greatly among counts separated by 2–3 days, while Seriola lalandi(Carangidae) and Alutera monoceros(Monacanthidae) abundances were more stable, indicating greater residence times at FADs for these two species. Marked differences in fish assemblages occurred between times when predators were present and absent, with few small fishes being observed when piscivorous predators occurred at FADs, regardless of season. Furthermore, abundances of C. hippurus and A. monoceros were correlated with current speed, with greatest abundances observed when currents were strong and weak, respectively. The results indicated that much of the temporal variability in fish assemblages at moored FADs could be explained by biological and physical factors.

History

Journal

Journal of Fish Biology

Volume

66

Pagination

1237-1260

Location

London, Eng.

ISSN

0022-1112

eISSN

1095-8649

Language

eng

Publication classification

C1.1 Refereed article in a scholarly journal

Issue

5

Publisher

Wiley

Usage metrics

    Research Publications

    Exports

    RefWorks
    BibTeX
    Ref. manager
    Endnote
    DataCite
    NLM
    DC