Hot Topics in Ecology

A drop in the ocean: marine fish releases in Australia

More fish in can mean more fish out
Synthesis by Prof Neil R. Loneragan, Dr Matthew D. Taylor & Dr James R. Tweedley, Murdoch University
  • Declining fish landings and increasing recreational fishing create an impetus to increase marine fish production through wild release of fish grown in aquaculture.
  • Recent release programs, informed by ecological knowledge and quantitative models, have shown that recruitment, competition with the same species and predation greatly influence the survival of released fish to capture.
  • Management policies are encouraging release programs that are monitored, evaluated and adaptively managed so that “more fish in can mean more fish out”.
From rearing to recapture: The aquaculture-based enhancement of Eastern King Prawn in New South Wales. This release program is one of ~14, including species of prawns, crustaceans and fish, which have been researched for release in Australia since the early 1990s (Photos: Matthew D. Taylor).

Release of fish bred in aquaculture into the ocean to enhance marine fisheries has expanded rapidly over the last 20 years, driven by declining fish stocks in Asia and increasing recreational fishing pressure in western countries. Significant advances in release programs include a solid conceptual foundation, guiding principles to minimise environmental impacts and to maximise fisheries outcomes. Major ecological questions that determine the appropriateness of releases include: Is the population recruitment limited? Will the scale of release exceed the environmental carrying capacity? Will the release have negative impacts (e.g., disease) on the wild population or ecosystem?

In a global context, the scale of releases in Australia is small (millions of released individuals each year), especially compared with those in China and Japan (billions released). Australian releases focus on small-scale, highly-targeted releases in direct response to recruitment limitation. Programs for the Eastern King Prawn and Western School Prawn both tested prawns for disease before release. Additionally, these programs have determined the best release sites, times and densities to reduce the chance of negative effects of high-density releases, such as slower growth and higher predation rates (“more fish in = less out”). Results from the Eastern King Prawn program and those from a program for Black Bream in the Blackwood River Estuary show that the released prawns and fish contributed significantly to fisheries stocks and that the Black Bream also contributed to the spawning population.

These release programs, which were informed by ecological research and quantitative modelling, have demonstrated that “more fish in can mean more fish out” and highlight the value of monitoring, evaluating, and adaptively managing releases to maximise their potential benefits. Management policies in Western Australia and New South Wales, combined with Environmental Impact Assessment such as that required in NSW, provide a mechanism for fostering responsible release programs.

Hot Topic Lead Author: 
Name: Prof Neil R. Loneragan
Phone: 08 9360 6453

Name: Dr Matthew D. Taylor
Phone: 02 9385 2079

Name: Dr James R. Tweedley
Phone: 08 93602823

ID Title Location Type
9304 Grant W. S., Jasper J., Bekkevold D. & Adkison M. (2017) Responsible genetic approach to stock restoration, sea ranching and stock enhancement of marine fishes and invertebrates. Reviews in Fish Biology and Fisheries 27: 615-49. Global A review.
9303 Cottingham A., Hall N. G. & Potter I. C. (2015) Performance and contribution to commercial catches and egg production by restocked Acanthopagrus butcheri (Sparidae) in an estuary. Estuarine, Coastal and Shelf Science 164: 194-203. Blackwood Estuary Field-based sampling.
9198 Andersen K. H., Jacobsen N. S., Jansen T. & Beyer J. E. (2017) When in life does density dependence occur in fish populations? Fish and Fisheries 18, 656-67. Global Simulation
9199 Bell J. D., Watson R. A. & Ye Y. (2017) Global fishing capacity and fishing effort from 1950 to 2012. Fish and Fisheries 18, 489-505. Global Simulation
9201 Bell J. D., Leber K. M., Blankenship H. L., Loneragan N. R. & Masuda R. (2008) A new era for restocking, stock enhancement and sea ranching of coastal fisheries resources. Reviews in Fisheries Science 16, 1-9. Global Review paper
9202 Bell, J.D., P.C. Rothlisberg, J.L. Munro, N.R. Loneragan, W.J. Nash, R.D. Ward, and N.L. Andrew. 2005. Restocking and stock enhancement of marine invertebrate fisheries. Advances in Marine Biology 49: 1-353. Global Review paper
9204 Blankenship H. L. & Leber K. M. (1995) A responsible approach to marine stock enhancement. American Fisheries Society Symposium 15, 167-75. Global Review paper
9205 Blount C., O’Donnell P., Reeds K., Taylor M. D., Boyd S., Van derWalt B., McPhee D. P. & Lincoln Smith M. (2017) Tools and criteria for ensuring estuarine stock enhancement programs maximise benefits and minimise impacts. Fisheries Research 186, 413-25. New South Wales (Australia) Methodological paper
9206 Broadley A. D., Tweedley J. R. & Loneragan N. R. (2017) Estimating biological parameters for penaeid restocking in a temperate Australian estuary. Fisheries Research 186, 488-501 Swan-Canning Estuary (Australia) Field-based sampling paper
9207 Camp E. V., Larkin S. L., Ahrens R. N. M. & Lorenzen K. (2017) Trade-offs between socioeconomic and conservation management objectives in stock enhancement of marine recreational fisheries. Fisheries Research 186, 446-59. Florida (USA) Simulation
9208 Chenoweth E. M., Straley J. M., McPhee M. V., Atkinson S. & Reifenstuhl S. (2017) Humpback whales feed on hatchery-released juvenile salmon. Royal Society Open Science 4. Southeast Alaska (USA) Field-based sampling paper
9209 Doherty, P.J. 1999. Recruitment limitation is the theoretical basis for stock enhancement in marine populations. In Stock Enhancement and Sea Ranching, ed. B.R. Howell, E. Moksness and T. Svåsand, 9-21. Oxford: Fishing News Books. Australia Review paper
9210 Hamasaki, K., Kitada, S. (2008). Potential of stock enhancement for decapod crustaceans. Reviews in Fisheries Science,16:1,164- 174. Global Simulation
9211 Hilborn, R. 1998. The economic performance of marine stock enhancement projects. Bulletin of Marine Science 62: 661-674. Global Review paper
9212 Hindar K., Ryman N. & Utter F. (1991) Genetic Effects of Cultured Fish on Natural Fish Populations. Canadian Journal of Fisheries and Aquatic Sciences 48, 945-57. Global Review paper
9213 Hixon, M. A., and M. H. Carr. 1997. Synergistic predation, density dependence, and population regulation in marine fish. Science 277:946-949. Bahamas Field-based sampling paper
9214 Kitada S. & Kishino H. (2006) Lessons learned from Japanese marine finfish stock enhancement programmes. Fisheries Research 80, 101-12. Japan Review paper
9215 Kitada S., Shishidou H., Sugaya T., Kitakado T., Hamasaki K. & Kishino H. (2009) Genetic effects of long-term stock enhancement programs. Aquaculture 290, 69-79. Japan Review paper
9216 Leber K. M. & Arce S. M. (1996) Stock enhancement in a commercial mullet, Mugil cephalus L., fishery in Hawaii. Fisheries Management and Ecology 3, 261-78. Hawaii Field-based sampling and simulation
9217 Loneragan, N.R., G.I. Jenkins, and M.D. Taylor. 2013. Marine stock enhancement, restocking, and sea ranching in Australia: Future directions and a synthesis of two decades of research and development. Reviews in Fisheries Science 21: 222-236. Australia Review paper
9218 Lorenzen K. (2005) Population dynamics and potential of fisheries stock enhancement: practical theory for assessment and policy analysis. Philosophical Transactions of the Royal Society B: Biological Sciences 360, 171.
9220 Lorenzen K. (2014) Understanding and managing enhancements: why fisheries scientists should care. Journal of Fish Biology 85, 1807-29. Global Review paper
9221 Lorenzen K., Agnalt A.-L., Blankenship H. L., Hines A. H., Leber K. M., Loneragan N. R. & Taylor M. D. (2013) Evolving context and maturing science: aquaculture-based enhancement and restoration enter the marine fisheries management toolbox. Reviews in Fi Global Review paper
9222 Lorenzen K. & Enberg K. (2002) Density-Dependent Growth as a Key Mechanism in the Regulation of Fish Populations: Evidence from among-Population Comparisons. Proceedings: Biological Sciences 269, 49-54. Northern Europe and the USA Simulation
9223 Lorenzen, K., K.M. Leber, and H.L. Blankenship. 2010. Responsible approach to marine stock enhancement: An update. Reviews in Fisheries Science 18: 189-210. Global Review paper
9224 Pile A. J., Lipcius R. N., van Montfrans J. & Orth R. J. (1996) Density-Dependent Settler-Recruit-Juvenile Relationships in Blue Crabs. Ecological Monographs 66, 277-300. USA Field-based sampling and laboratory experiments
9225 Svåsand T., Kristiansen T. S., Pedersen T., Salvanes A. G. V., Engelsen R., Nævdal G. & Nødtvedt M. (2000) The enhancement of cod stocks. Fish and Fisheries 1, 173-205. Norway, Denmark, Sweden the Faroe Islands and the USA Review paper
9226 Sloychuk, J. R., D. P. Chivers, and M. C. O. Ferrari. 2016. Juvenile lake Sturgeon go to school: life-skills training for hatchery fish. Transactions of the American Fisheries Society 145:287-294. Canada and northern USA
9227 Taylor M. D., Chick R. C., Lorenzen K., Agnalt A.-L., Leber K. M., Blankenship H. L., Haegen G. V. & Loneragan N. R. (2017) Fisheries enhancement and restoration in a changing world. Fisheries Research 186, Part 2, 407-12. Global Review paper
9228 Tringali, M.D. 2006. Bayesian approach for the genetic tracking of cultured and released individuals. Fisheries Research 77: 159-172. Florida (USA) Methodological paper
9229 Wang Q., Zhuang Z., Deng J. & Ye Y. (2006) Stock enhancement and translocation of the shrimp Penaeus chinensis in China. Fisheries Research 80, 67-79. China Review paper
9230 Ye Y., Loneragan N., Die D., Watson R. & Harch B. (2005) Bioeconomic modelling and risk assessment of tiger prawn (Penaeus esculentus) stock enhancement in Exmouth Gulf, Australia. Fisheries Research 73, 231-49. Exmouth Gulf (Australia) Simulation

Further information about this topic contact:

Prof Neil R. Loneragan
08 9360 6453

Chair, Hot Topics Editorial Board
Dr Rachel Standish