How the moon affects fish activity

New light has been thrown on the relationship between the moon and fish activity by NSW Department of Primary Industries (DPI) scientists.

DPI research scientist Michael Lowry said information collected as part of the NSW DPI Gamefish Monitoring Program had unearthed a greater understanding of the interaction between moon phase and key species targeted by off-shore anglers.

"Results showed significant relationships between catch rates and lunar phase for black marlin, blue shark, shortfin mako, dolphin fish and yellowfin tuna," Dr Lowry said.

"Physiological differences between fish species appears to explain what is happening within the marine environment in response to the lunar phase.

"Prey fish dive deeper to avoid the light of the full moon, but some predator fish are unsuited to spend a long time in deeper, colder waters."

Dr Lowry said swimming depths have been found to be much deeper around the full moon for bluefin tuna, bigeye tuna, sword fish and school sharks - all of which have an ability to maintain body temperature in cooler waters.

"In contrast, billfish like Black marlin remain in the surface waters during a full moon, with occasional short dives of up to 200m," he said.

"They are surface feeders despite the lunar migration to depth of many prey species.

"As a result, billfish forage over a wide area which increases their chances of taking a bait and being caught by anglers."