Title:

Tasmania's coastal reefs: deep reef habitats and significance for finfish production and biodiversity

Project Number:

2014-012

Organisation:

University of Tasmania (UTAS)

Principal Investigator:

Jeremy Lyle

Project Status:

Completed

FRDC Expenditure:

$227,904.26

Program(s):

Environment

Need

Reefs represent important habitats for commercially and recreationally exploited species under Tasmanian jurisdiction. In Tasmania, shallow reefs (<25 m) are significant to commercial and recreational fisheries for scalefish and invertebrates. These include live-fish fisheries for banded morwong (gillnet) and wrasse (trap and line), as well as recreational and commercial gillnet fisheries for species such as bastard trumpeter, striped trumpeter and blue warehou. Other species including jackass morwong, various leatherjackets and boarfish, are also relatively commonly caught on shallow inshore reefs. Most of these species also occur at greater depths but as only striped trumpeter are subjected to a targeted (line) deepwater fishery; deep reefs are therefore assumed to be important refuges from fishing pressure. While recent research has improved our understanding of the population biology of some of these species, management of these fisheries is primarily based on characteristics observed from shallow reefs. The lack of quantitative information on the significance of deep reef habitats as refuges and/or their role in population structuring limits our ability to undertake informed risk assessments of the impacts of current fishing practices and evaluate alternative management options. While the structure, composition and functioning of shallow-reefs (<10m) and their associated fish communities has been studied extensively, the ecological importance of deeper reef ecosystems has not been investigated apart from recent baseline studies of offshore Commonwealth MPAs. Linkages and associations between fish communities in shallow and deeper reef areas remain a distinct knowledge gap.

Objectives

1. Characterise reef fish communities on the east and south-east coasts of Tasmania by depth and habitat structure

2. Describe habitat associations for the key reef fish species and their links to life-history characteristics

3. Assess the potential to use habitat characteristics to describe and predict fish community structure

4. Assess the significance of reef habitats for fisheries production and fishery assessments

2014-012-DLD - Tasmania's coastal reefs: deep reef habitats and significance for finfish production and biodiversity

Final Report
ISBN:978-1-86295-902-6
ISSN:
Author(s):Jeremy Lyle
Date Published:May 2017
Principal Investigator: Jeremy Lyle
 
Key Words: Temperate reefs; Reef habitat classification; Reef fish assemblages; Reef fish fisheries; Baited remote underwater video (BRUV); Remotely operated vehicle (ROV); Gillnets; Bayesian Ordination and Regression Analysis, Relative abundance (maxN); Species distribution modelling.
 
Summary: This study surveyed fish communities associated with two large patches of coastal reef that had been mapped previously using high-resolution multibeam acoustics.  The reefs, located on the east and south coasts of Tasmania, are the focus of important commercial and recreational fisheries. The surveys utilised underwater video methods, including baited remote underwater video (BRUV) and remotely operated vehicle (ROV), as well as gillnets.  Patterns in community composition, interactions between species and relationships with reef characteristics were described using multivariate statistical analyses.  This information was assessed for its utility to develop predictive distribution and abundance maps of key species.