Baywide Monitoring of Key Fishery Species in Seagrass Beds Sub-Program
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Baywide Monitoring of Key Fishery Species in Seagrass Beds Sub-Program Milestone Report No. 7 (April 2011) No. 136 July 2011 Baywide Monitoring of Key Fishery Species in Seagrass Beds Sub -Program Milestone Report No. 7 (April 2011). Neil Hutchinson, Greg Jenkins and Andrew Brown July 2011 Fisheries Victoria Technical Report Series No. 136 If you would like to receive this Copyright The State of Victoria, Department of information/publication in an Primary Industries, 2011. accessible format (such as large This publication is copyright. No part may be print or audio) please call the reproduced by any process except in accordance Customer Service Centre on: with the provisions of the Copyright Act 1968. 136 186, TTY: 1800 122 969, Authorised by the Victorian Government, GPO Box 4440, Victoria 3001. or email Printed by Fisheries Victoria, Queenscliff, [email protected] Victoria Published: Fisheries Victoria Hutchinson, N. Jenkins, G. and Brown, A. (2011). Department of Primary Baywide Monitoring of Key Fishery Species in Industries, Queenscliff Centre Seagrass Beds Sub-Program. Milestone Report PO Box 114, Queenscliff, Victoria No. 7 (April 2011). Fisheries Victoria Technical 3225 Australia. Report Series No. 136, July 2011, Department of Primary Industries, Queenscliff, Victoria, Australia. 37pp. General disclaimer This publication may be of assistance to you but the State of Victoria and its employees do not ISSN 1835-4785 guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all ISBN 978-1-74264-910-8 liability for any error, loss or other consequence which may arise from you relying on any information in this publication. Baywide Monitoring of Key Fishery Species in Seagrass Beds Milestone Report #7 ii Executive Summary The objective of the Monitoring Key Fishery In shallow seagrass at Blairgowrie, significantly Species in Seagrass Beds Sub-Program is to more fish were sampled in autumn 2011 than collect data on the types and abundance of fish spring 2010, but not autumn 2010, while no in shallow and deeper seagrass beds that will fill significant differences were apparent at Mud existing knowledge gaps and assist in Islands or St Leonards. In deep seagrass at understanding the significance of any observed Blairgowrie and Mud Islands, significantly more changes in seagrass habitat for these fish. fish were sampled in autumn 2011 than spring 2010 and autumn 2010, but no significant Surveys are undertaken to compare the differences were apparent at St Leonards. distribution and abundance of fish in shallow (< 1 m) and deeper (2–8 m) seagrass beds in three areas of PPB. These surveys are conducted Fish size in spring and autumn each year and results are Size frequencies of finfish varied significantly analysed to compare against results for the but inconsistently between dates, and between preceding seasonal survey and for the same deep and shallow seagrass beds, with the largest seasonal survey 12 months prior. Specific fish collected in autumn 2011 recorded in comparisons are made between regions and shallow seagrass. depths for species richness, fish abundance, length frequency distribution and fish Assemblage structure assemblage structure. The greatest difference in fish assemblage Sampling of fish in shallow and deep water structure during autumn 2011 was between seagrass beds was completed successfully at the deep and shallow seagrass beds. Fish Blairgowrie, Mud Islands and St Leonards sites assemblage structure also varied significantly in autumn (April) 2011. A total of 45 fish species with time, and was significantly different (43 finfish and two squid) from 22 families (20 between autumn 2011 and spring 2010 at both families for finfish and two families for squid) depths, and between autumn 2011 and autumn was sampled from all sites. 2010 in deep seagrass beds only. Species richness and fish Conclusions abundance Results from autumn 2011 sampling continue to show that shallow and deep seagrass beds in Species richness was significantly higher in PPB have distinct fish assemblages. As with shallow seagrass compared with deep seagrass previous sampling events from this sub- in autumn 2011 at St Leonards, but not at program, shallow seagrass beds tend to be Blairgowrie or Mud Islands. dominated by small, schooling species that do In shallow seagrass beds at St Leonards, species not occur in deeper seagrass. Seasonal patterns richness was higher in autumn 2011 than spring of change in assemblage structure can now be 2010, but not different to autumn 2010. There clearly seen, partly due to distinct population were no significant differences in species changes in species such as bridled leatherjackets richness at this site in deep seagrass beds in deep and shallow seagrass beds, wide-body between autumn 2011 and the two previous pipefish in both deep and shallow seagrass beds, seasons. At Blairgowrie and Mud Islands, and the seasonal presence of King George species richness in deep seagrass beds was whiting in shallow seagrass beds. A positive higher in autumn 2011 than spring 2010 and relationship between seagrass biomass/length autumn 2010, but no significant differences were and fish abundance/species richness also apparent in shallow seagrass beds at these sites. continues to be apparent. Fish abundances were significantly higher in In general, based on previous studies, variability shallow seagrass compared with deep seagrass in fish assemblages in shallow and deep in autumn 2011 at Mud Islands and St Leonards, seagrass beds during the autumn 2011 reporting but not at Blairgowrie. period was within what would be expected in PPB. Baywide Monitoring of Key Fishery Species in Seagrass Beds Milestone Report #7 iii Table of Contents Executive Summary............................................................................................. iii Species richness and fish abundance...................................................................................................................iii Fish size .....................................................................................................................................................................iii Assemblage structure..............................................................................................................................................iii Conclusions...............................................................................................................................................................iii Introduction............................................................................................................ 1 Purpose of this report................................................................................................................................................1 Materials and Methods......................................................................................... 2 Statistical model ......................................................................................................................................................2 Definitions ..................................................................................................................................................................2 Data Management......................................................................................................................................................2 QA/QC......................................................................................................................................................................2 Results...................................................................................................................... 4 Species Richness......................................................................................................................................................4 Fish Abundance ......................................................................................................................................................4 Wide-body pipefish ................................................................................................................................................4 Fish Size....................................................................................................................................................................5 Fish and Seagrass....................................................................................................................................................5 Fish assemblage structure......................................................................................................................................5 Discussion............................................................................................................... 6 Conclusions.................................................................................................................................................................7 Acknowledgements............................................................................................... 8 References ............................................................................................................... 9 Appendix 1 Results ............................................................................................. 11 Species Richness....................................................................................................................................................11