Counting reef fish could now be easier


Marine biologists have solved a conundrum that has stumped them for years – how to count reef fish.

Biologists from the University of Miami and the NOAA Fisheries Service developed a method of surveying reefs after realising that simply counting fish landed at docks was not an effective way of evaluating reef populations.

The programme has taken over 30 years to develop. Steven Thur acting manager of NOAA’s Coral Reef Conservation Program said: "The results of this study can be utilised to support stock assessments of principal exploited species, evaluate the performance of 'no-take' marine reserves, and assess community health for many non-target reef fish species."

Earlier methods used started with scientific divers counting the number and sizes of reef fish by species.

Then in the mid-1990s a statistical method was developed which involved dividing the entire Florida Keys reef ecosystem into small sections classified according to simple features like soft and hard bottom, coral, and other features that related to where fish might live.

This monitoring framework allowed the researchers to calculate the abundance and size-structure of more than 250 exploited and non-target reef fishes from Miami to Key West and out to the Dry Tortugas.

"Through our collaborative work we were able to create a framework that brings together cutting edge techniques in underwater sampling, coral reef mapping and statistical survey design that will serve us well as our marine resources continue to be impacted by fishing, habitat degradation and environmental changes," Smith said.

Although the team began testing its theories in the Florida Keys, the new framework is fully transferable to other U.S. coral reef ecosystems and areas around the globe.

Jerry Ault part of the University of Miami’s team said:"We have already been using this methodology in the North-western Hawaiian Islands to assess multispecies reef fish populations, and federal and local management agencies are extremely pleased with the results of these efforts. We hope to take this approach to new areas in order to have a single, quantitative framework to assess coral reefs at local, regional, national, and international spatial scales."

For further information see the paper: Multispecies survey design for assessing reef-fish stocks, spatially explicit management performance, and ecosystem condition. Steven G. Smith, Jerald S. Ault, James A. Bohnsack, Douglas E. Harper, Jiangang Luo and David B. McClellan Fisheries Research Vol 109 Issue 1.