Otoliths of Common Australian Temperate Fish: A Photographic Guide

By Dianne Furlani, Rosemary Gales and David Pemberton

The accurate identification of fish ‘ear-bones’, known as otoliths, is essential to determine the fish prey of marine and terrestrial predators. Fish otoliths are species-specific when combining size, shape and surface features, and can remain undigested for long periods. As a result, they can indicate which fish make up the diet of various predators, including cephalopod, seabird, marine mammal and fish species. Such studies are crucial for understanding marine ecosystems, and trophodynamics in particular. Increasingly, these methods are being used to understand the diet of some terrestrial predators, also extending to that of humans in archaelogical studies.

Otoliths of Common Australian Temperate Fish offers users a verified reference collection to assist in the accurate identification of species and size of fish using otoliths. It covers 141 fish species from a broad geographic range of the Australian temperate region and includes commercial and non-commercial fish species. A standardised written description of the otolith structure, size and surface features is provided for each species. Included are brief distribution and ecology notes, and regression for both otolith and fish lengths, together with high-quality SEM photographs of the otolith described.

This guide will be an essential reference for marine scientists and marine mammal researchers; ornithologists, fisheries researchers and fish biologists studying age and growth or comparative anatomy; and archaeologists.

Winner of the 2008 Whitley Award for Zoological Manual.

• Language: English
• Publisher: CSIRO PUBLISHING
• Release date: Aug 20, 2007
• ISBN: 9780643100046

Book preview

OTOLITHS OF COMMON

AUSTRALIAN TEMPERATE FISH

OTOLITHS OF COMMON

AUSTRALIAN TEMPERATE FISH

A PHOTOGRAPHIC GUIDE

Dianne Furlani, Rosemary Gales and David Pemberton

CSIRO

 PUBLISHING

© CSIRO 2007

All rights reserved. Except under the conditions described in the Australian Copyright Act 1968 and subsequent amendments, no part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, duplicating or otherwise, without the prior permission of the copyright owner. Contact CSIRO PUBLISHING for all permission requests.

National Library of Australia Cataloguing-in-Publication entry

Furlani, Dianne.

Otoliths of common Australian temperate fish: a photographic guide.

Bibliography.

Includes index.

ISBN 9780643092556 (hbk.).

1. Otoliths – Classification – Pictorial works.

2. Otoliths – Laboratory manuals. 3. Fishes – Age determination – Australia.

I. Gales, Rosemary, 1960–. II. Pemberton, David. III. Title.

597.1440994

Published by

CSIRO PUBLISHING

150 Oxford Street (PO Box 1139)

Collingwood VIC 3066

Australia

Front cover

Pseudophycis bachus (Red cod), distal surface of otolith;

Seriolella brama (Blue warehou), proximal surface of otolith;

Diodon nichthemerus (Globefish), proximal surface of otolith.

Back cover

Dolphin (photo: istockphoto);

Tetractenos glaber (Smooth toadfish), proximal surface of otolith;

Shy albatross (photo: DPIW).

Set in 10/13 ITC New Baskerville and Optima

Cover and text design by James Kelly

Typeset by Desktop Concepts Pty Ltd, Melbourne

Printed in Australia by Ligare

CONTENTS

Acknowledgements

Introduction

Methods and materials

Definition of terms

Abbreviations

Species List (systematic order)

Otolith descriptions and images

References

Index

ACKNOWLEDGEMENTS

Many individuals have provided their time and expertise in the development of this guide – and we thank them all. We are especially grateful to Tony Rees (CMAR) and Wieslaw Jablonski (UTAS) for assistance with the Scanning Electron Microscopy and to Peter Last for assistance with identification of selected fish species. The former Department of Sea Fisheries and the Inland Fisheries Commission are gratefully acknowledged for providing access to many prey specimens. We are indebted to Norbert Klages for his extensive input over the protracted development of this guide. We are also grateful to Louise Bell for her knowledge in image preparation, Jo Eberhard for assistance with line drawings, and Roger Kirkwood for input into several regression analyses. We would particularly like to thank George Jackson and Sue Gibbs for their manuscript review and invaluable comments. And lastly, Oliver Gales and Caitlin Gunn are thanked for their assistance with final detail checking – Elsa Gales and Simon Gunn are thanked for letting them.

INTRODUCTION

Otoliths of Common Australian Temperate Fish: A Photographic Guide has been compiled primarily as a reference work for use in studies of the dietary composition of a range of marine animals, including fish, sharks, cephalopods, mammals, penguins and other seabirds.

Ecosystem studies have been recognised as being increasingly important to the understanding of the marine system (EPBC Act, 1999). The study of the diet of marine animals, particularly the identification of teleost otoliths from the gut content of piscivorous predators, is integral to an understanding of their ecology and interactions with commercial fisheries (Croxall 1987, Gales and Pemberton 1994, McMahon et al. 1999, Tasker et al. 2000, Bulman et al. 2001, Childerhouse et al. 2001, Bradshaw et al. 2003). These dietary studies are presently limited by the lack of taxonomic accuracy in identifying prey items.

Otolith structures, primarily sagittal otoliths, vary widely among fish species and are recognised as being species-specific (Maisey 1987). Being dense, otoliths are one of the last features to be digested and can therefore often be obtained from stomach contents and scats, and their distinctive morphology compared with reference otoliths to identify the individual prey species. As the range of diet studies increases, it has become apparent that guides to the otoliths of the fish of different regions are an essential element in the toolbox of ecologists.

Otolith publications are available for specific regions around the world: the northeast Atlantic (Harkonnen 1986), the north-west Atlantic (Campana 2004), the south Pacific (Garcia-Godos Naveda 2001), the western Indian Ocean and south-eastern Atlantic (Smale et al. 1995), the Southern Ocean (Hecht 1987) and the Australian Antarctic territory, including Macquarie and Heard Islands (Williams and McEldowney 1990). These publications may include some species occurring in Australian waters, but, until now, limited information on otoliths has been available for Australian marine species.

This guide is designed to describe the sagittal otoliths of fish species that occur predominantly in the temperate waters of south-east Australia, but may extend from Western Australia through to New South Wales. The species included are mostly benthic, benthopelagic or mesopelagic in origin, or from inshore coastal habitats. From the sampling opportunities available to us, a total of 141 species, from 68 families and 15 orders, were collected and included, but this guide does not cover all fish species known from the area. As such, there is still a need for further collection and identification of otoliths, particularly for pelagic species.

Alternative research uses of otoliths

Otoliths, which are present in all bony fishes, consist of a calcium carbonate (usually aragonite) crystal that grows continuously by accretion over the life of the fish. They are contained within a membranous labyrinth in paired otic capsules on either side of the skull. Three pairs of otoliths are present – sagittae, asteriscus and lapillus – with the sagittae being the largest in most bony fishes. Primarily an organ associated with balance, movement and hearing (Tavolga et al. 1981, Popper and Lu 2000), findings from otolith research have provided fisheries scientists with several valuable tools, particularly in the areas of fish ageing and population studies.

Otoliths have become the primary structure for estimation of fish age, predominantly using otolith increment analysis techniques in adults, and applying alizarin marking techniques in larvae and juveniles. As these techniques have developed, the importance of accuracy and precision in age determination has become increasingly evident (e.g. Beamish and McFarlane 1983, Chambers and Miller 1995, Secor et al. 1995, Campana 2001). As such, validations of methods for estimating fish age continue to be assessed for many species (e.g. Milton et al. 1995, Fowler and Short 1998, Stewart et al. 1999, Dwyer et al. 2001, Dwyer et al. 2003).

Otoliths have proved valuable beyond the studies of feeding, age and growth alone. Research into studies of populations – stock assessment and stock discrimination, together with fish migration and movement studies – all benefit from data derived from otoliths.

Through the examination of otolith microstructure, patterns of chemically or thermally induced increments have been used to distinguish between populations or stocks of fish (Gunn et al. 1992, Proctor et al. 1995, Secor 1999, Campana and Thorrold 2001, Gao et al. 2001, Bastow et al. 2002, and others). As the chemical composition can be distinct for different water masses, trace elements incorporated into the surface of the otolith reflect the physical and chemical characteristics of the ambient water, and can be used to discriminate between groups of fish that have spent part of their lives in different environments (e.g. Thresher 1999, Campana et al. 2000). Strontium to calcium ratios have been used as indicators of salinity, to show migration between freshwater, estuaries and saltwater environments (e.g. Edmonds et al. 1999, Bath et al. 2000, Pontual et al. 2003). Stable isotopes, particularly oxygen, have been used as indicators of the metabolic and temperature history of fish (e.g. Kalish 1991, Weidman and Millner 2000, Lenanton et al. 2003, Ayvazian et al. 2004).

Other disciplines have also benefited from otolith research. Studies of archaeology and palaeoclimatology have based reconstructions of palaeoclimate on the elemental and isotopic composition of recovered otoliths (Anderson et al. 1997, Patterson 1998, Ivany et al. 2000, Wurster and Patterson 2001). Studies of ecology and ecomorphology have drawn on the implications of otolith structures and function, and tested these variations for some species and habitats (Gauldie 1988, Sideleva and Zubina 1990, Lombarte 1992, Arellano et al. 1995, Paxton 2000, Volpedo and Echeverria 2003) to provide a further source of information to fisheries studies.

METHODS AND MATERIALS

The material described and illustrated in this guide was collected from fishing boats working off the north-west and south coast of Tasmania, between 1985 and 1987, and from CSIRO Southern Surveyor research cruises between Wilsons Promontory (Victoria) and Bermagui (New South Wales), between April and December 1996, predominantly trawling in depths from 25 to 200 m. In addition, species were collected at the Melbourne markets from fishing operations in Bass Strait waters. Once fish were identified, individual fish lengths and weights were recorded and otoliths removed and stored in seed envelopes or gelatin capsules.

Otoliths were later soaked in distilled water and cleaned with a soft brush to remove any blood, tissue or otic fluids. Cleaned otoliths were weighed, measured and mounted onto numbered stubs, using double-sided carbon tape. Stub numbers were cross-referenced to the individual species details. Mounted otoliths were lightly sputter-coated as a requirement for scanning electron microscopy. Samples from CSIRO Marine and Atmospheric Research (CMAR) were sputter-coated with platinum, and samples from Tasmanian Museum and Art Gallery (TMAG) and Department of Sea Fisheries (DSF – currently Tasmanian Aquaculture and Fisheries Institute) were sputter-coated with gold. All mounted otoliths where then stored in lidded containers to minimise dust or damage.

Scanning electron micrograph (SEM) images were taken of all otoliths. Descriptions were based on these images and original specimens. Where possible, a size range of otoliths from each specimen was photographed and described. Where there was extensive variation with ontogeny, this was also stated. All material described are sagittal otoliths, either left or right otoliths, and generally proximal side only, unless diagnostic features were found to occur on the distal surface. These instances are individually noted.

SEM images from CSIRO collected otoliths were carried out at the CSIRO laboratories in Hobart and were stored as TIFF files using Powerpoint software. Raw images were enhanced by sharpening contrast and making images lighter or darker to increase clarity. As the minimum SEM magnification was X10, the largest otoliths needed to be scanned in parts and ‘pasted’ together.

SEM images of DSF and TMAG collected otoliths were carried out at the University of Tasmania, Central Science Laboratories, and stored as micro-graphic negatives.

The species contained in this guide have been arranged by phylogenetic sequence of Order and Family, with species then listed alphabetically by genus. Scientific names are shown in bold italic typeface, with common names and previous nomenclature also provided after the recognised species name. This allows easy cross-referencing of predator–prey information from published literature where previous taxonomic naming has been used.

Taxonomic names follow the nomenclature contained within the Codes for Australian Aquatic Biota (CAAB) website (http://www.marine.csiro.au/caab/) (Rees et al. 2000) and, where included, other names cited in Gomon et al. (1994) and Last et al. (1983). For species not included in these latter references, previous taxonomic names follow the California Academy of Sciences, Catalog of Fishes On-line nomenclature, (http://www.calacademy.org/research/ichthyology/catalog/fishcatsearch.html) which is regularly updated. Similarly, we have included the official common name for each species in bold typeface (obtained from CAAB), followed in brackets by other previously used common names.

Fish length and weight data has been recorded at point of capture/collection. Otolith length data has been recorded at the time of otolith extraction, after cleaning. Where available, otolith weight and primordium position are from the Marine and Freshwater Resources Institute (MAFRI – currently Central Ageing Facility (CAF)) Final Reports 1 and 2, compiled for CSIRO from material collected during the listed Southern Surveyor research cruises. Brief details of distribution and ecology have also been provided, as a means of further aiding species identification.

Line drawings of fish have been provided for each species. Used together with distributional and ecological information, these provide a quick reference to the fish morphology, and some assumption of the likelihood of predator–prey interactions. Line drawings have been predominantly taken from Fishes of Tasmania (Last et al. 1983), with permission from copyright holders, Department of Primary Industry and Water, Tasmania. The remainder are sourced from Gomon et al. (1994) or redrawn from Smith and Heemstra (1986).

For each fish species, references are made to known data or published information on predators of that species. In many cases references identify the prey fish to only the Family or Genus level. In these instances, comment is made that the particular predator preys upon undistinguished species of that particular Family or Genus. If the respective group has more than one species represented in the atlas, we place the reference with the first species.

Morphometric data sets

Early morphometric studies identified a positive relationship between fish size and otolith size (Trout 1954, Templemann and Squires 1956), between fish weight and otolith length (Casteel 1974), and later between fish length and otolith length (Frost and Lowry 1981, Wyllie Echeverria 1987, Gamboa 1991). Generally, a simple linear regression can be used to describe these relationships.

For species within this guide, information regarding fish length, fish weight, otolith weight and otolith length were compiled from original unpublished data, with standard error and sample values provided. The source of this data is noted and includes morphometric measurements from CMAR research cruises (1984–86 and 1995–2002) and TMAG measurements collected during predator– prey studies (1984–90).

Because of the general lack of availability of this data to date, it was considered important to include all available length/weight data for the species included. As such, some data sets are very small. It should be emphasised that n and R values should be carefully noted when using these regressions.

Further limitations do exist in this technique, for example, for juvenile fishes or