Fish ecology

Fish Ecology research group is about  fish in sustainable and healthy habitats (FISHH). We do this by assessing fish diversity, abundance, size and movement patterns across much of the NSW coastline to assess how management might be best applied and to quantify management effectiveness and effects of a variety of human pressures. We aim to assess knowledge gaps in our understanding of threats to fish populations and work with traditional owners, stakeholders, the general public and managers to assist with management actions that may reduce these threats and their effects on fish populations and their habitats. The Fish Ecology theme is led by Dr Nathan Knott.

Research focus

Research under the Fish ecology theme supports the Marine Estate Management Strategy by providing data and information to support the Marine Integrated Monitoring Program (MIMP)

Within this research area we look at:

  • Identifying how fish use habitats and what works best to restore habitat quality, quantity and access for fish.
  • Measure and track the health of fish populations, using biological indicators, at multiple spatial and temporal scales
  • Applying experimental biology and ecology methods to establish cause and effect relationships, to test policy and management options

Current projects

State-wide reef fish monitoring

This program commenced in 2010 and uses a standardised method that is also being applied Australia-wide and globally. Surveys have been undertaking in 2010, 2011, 2015, 2016, 2022 and 2023, with resampling planned for 2027 and 2028. It provides an independent assessment of fishery target species such as snapper as well as the fish biodiversity. Nathan Knott, David Harasti, Hamish Malcolm, Matt Rees

Review of offshore anchoring

Shipping is vital to NSW trade and industry yet anchoring by these large vessels near ports may damage of seabed habitats and their associated marine life. This multi-agency project funded by the Marine Estate Management Strategy has quantified the ecological effects of offshore anchoring by large vessels along the Greater Sydney coastline. The Port Kembla Harbour Offshore Anchorage (Port Authority of NSW) was developed as part of this project to alleviate anchoring pressure on relatively intact rocky reef habitats, while directing anchoring to areas of deep sands or rocky reefs that have been already substantially altered. The current project is now moving to quantifying the recovery of the habitats and the associated biodiversity where anchoring has been alleviated. Matt Rees, Nathan Knott

Reviewing jetty designs

Seagrass beds are an important estuarine habitat, providing food and shelter for many marine animals. Seagrasses are marine plants that require sunlight to live and grow. Jetties and pontoons can pose a threat to the health of seagrasses as they may shade seagrasses from sunlight. This project is researching the design features of jetties that lead to the loss of seagrass. Nathan Knott, Matt Rees

Subtidal reef monitoring in the Greater Sydney region

Coastal reefs are important habitats that support a wide range of animals and plants, including many fish species caught by recreational and commercial fishers. This habitat in the Greater Sydney region is under increasing pressure from a range of threats such as pollution, coastal development and climate change. This project will monitor this habitat and its associated marine life to identify impacts and guide activities to manage threats. Nathan Knott, Matt Rees

Threats to estuarine fish assemblages

In the Greater Sydney region, estuaries, their habitats and associated species are under increasing threat from a range of stressors including pollution, and boating infrastructure, such as jetties, pontoons and moorings. This project will help understand the influence of boating infrastructure, stormwater runoff and natural habitats on estuarine fishes. Nathan Knott, Matt Rees

Assessing long-term changes and management of rocky reef biodiversity

A collaborative project between NSW DPI and the University of Tasmania has provided long-term data on the Jervis Bay and Batemans Marine Parks.  Fishes, invertebrates and algae are sampled by scientific divers across more 70 sites and have been regularly sampled over the last two decades providing a unique and quantitative understanding of the changes on these rocky reefs and the influence of marine park management actions.  Nathan Knott

Acoustic tracking of fishes to improve management and ecosystem functioning

This project has involved the development of one of the most sophisticated acoustic tracking systems in the world within Jervis Bay Marine Park.  This tracking array comprehensively covers multiple habitats across the Bay.  This array forms an important node in the National Integrated Marine Observing System along the NSW coastline. Nathan Knott

Key publications

Rees, M. J., N. A. Knott, K. L. Astles, D. S. Swadling, G. J. West, A. M. Ferguson, J. Delamont, P. T. Gibson, J. Neilson, and G. F. Birch. 2023. Cumulative effects of multiple stressors impact an endangered seagrass population and fish communities. Science of The Total Environment 904:166706.

Edgar, G. J., R. D. Stuart-Smith, F. J. Heather, N. S. Barrett, E. Turak, H. Sweatman, M. J. Emslie, D. J. Brock, J. Hicks, and B. French. 2023. Continent-wide declines in shallow reef life over a decade of ocean warming. Nature 615:858-865.

Day, J., N. A. Knott, D. Ayre, and M. Byrne. 2023a. Effects of habitat on predation of ecologically important sea urchin species on east coast Australian temperate reefs in tethering experiments. Marine Ecology Progress Series 714:71-86.

Day, J. K., N. A. Knott, D. Swadling, D. Ayre, M. Huggett, and T. Gaston. 2023b. Non‐lethal sampling does not misrepresent trophic level or dietary sources for Sagmariasus verreauxi (eastern rock lobster). Rapid Communications in Mass Spectrometry 37:e9435.

Lennox, R. J., F. G. Whoriskey, P. Verhelst, C. S. Vandergoot, M. Soria, J. Reubens, E. L. Rechisky, M. Power, T. Murray, I. Mulder, J. L. Markham, S. K. Lowerre-Barbieri, S. T. Lindley, N. A. Knott, S. T. Kessel, S. Iverson, C. Huveneers, M. Heidemeyer, R. Harcourt, L. P. Griffin, C. Friess, A. Filous, L. C. Fetterplace, A. J. Danylchuk, R. Daly, P. Cowley, S. J. Cooke, E. J. Chávez, A. Blaison, and K. Whoriskey. Globally coordinated acoustic aquatic animal tracking reveals unexpected, ecologically important movements across oceans, lakes and rivers. Ecography: e06801.

Pini-Fitzsimmons, J., N. A. Knott, and C. Brown. 2023. Recreational fishery discard practices influence use of tidal estuary by a large marine mesopredator. Marine and Freshwater Research 74:320-334.

Pini‐Fitzsimmons, J., V. Raoult, T. Gaston, N. A. Knott, and C. Brown. 2023. Diving into the diet of provisioned smooth stingrays using stable isotope analysis. Journal of Fish Biology 102:1206-1218.

Davis, T. R., N. A. Knott, C. Champion, and R. Przeslawski. 2023. Impacts of Climate Change on Densities of the Urchin Centrostephanus rodgersii Vary among Marine Regions in Eastern Australia. Diversity 15:419.

Udyawer, V., C. Huveneers, F. Jaine, R. C. Babcock, S. Brodie, M.J. Buscot, H. A. Campbell, R. G. Harcourt, X. Hoenner, E. J. I. Lédée, C. A. Simpfendorfer, M. D. Taylor, A. Armstrong, A. Barnett, C. Brown, B. Bruce, P. A. Butcher, G. Cadiou, L. I. E. Couturier, L. Currey-Randall, M. Drew, C. L. Dudgeon, R. G. Dwyer, M. Espinoza, L. C. Ferreira, A. Fowler, D. Harasti, A. R. Harborne, N. A. Knott, K. Lee, M. Lloyd, M. Lowry, T. Marzullo, J. Matley, J. D. McAllister, R. McAuley, F. McGregor, M. Meekan, K. Mills, B. M. Norman, B. Oh, N. L. Payne, V. Peddemors, T. Piddocke, R. D. Pillans, R. D. Reina, P. Rogers, J. M. Semmens, A. Smoothey, C. W. Speed, D. Meulen, and M. R. Heupel. 2023. Scaling of Activity Space in Marine Organisms across Latitudinal Gradients. The American Naturalist 201:586-602.