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Murray cod spawning and recruitment

Monitoring programs for Murray cod
NSW DPI Jun 16, 2020

Overview

Murray cod recreational fisheries are growing in popularity and many anglers are reporting improved fisheries for this species over the last few decades.

Much of this has resulted from stocking programs throughout the state. However, more is needed to fully understand spawning and recruitment for this species.
What is the difference between spawning and recruitment?
Murray cod spawning site during dry conditions.
Spawning is the process of fertilisation of eggs.
  
Recruitment is the next step after spawning where the larvae or small fish survive and have the opportunity to grow to an adult.

Successful spawning doesn’t always mean successful recruitment. As various environmental factors (e.g. food availability and environmental conditions) can influence this.
Murray cod eggs

How is DPI monitoring cod spawning and recruiting?

Image: Wild Murray cod from northern NSW

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Electrofishing is being used to monitor recruitment and survival of stocked fish as well as habitat preference of wild juvenile fish.

Radiotracking, larval sampling and underwater video are being used to monitor spawning and nesting cod. As well as larvae hatching and survival.

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Why have a closed season?

Murray cod display good parental care of eggs and monitor their nest for debris and predators.

This video shows a Murray cod guarding its nest and small larvae can be seen darting around.

How else are DPI monitoring murray cod fisheries?


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DPI have been building a strong program to monitor the recreational fishery for Murray cod.
This includes:
● Long term electrofishing surveys in the Murrumbidgee, Gwydir and Dumaresq to monitor population size structure.
● Monitoring effectiveness of stocking in impoundments.
● Monitoring angler catches, fish population size structure and fish effort with creel surveys and citizen science. 

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What’s next for Murray cod monitoring?
● Hydroacoustic surveys will be used to estimate population size/ biomass of Murray cod and other natives in impoundments.
● Keep an eye of the DPI website and Facebook pages for regular monitoring updates.