Assessing Maldivian Fish Populations

Image: Fish Head, a famous Maldivian dive site



After a busy field trip, the fish team sadly had to say goodbye to the other teams as well as to the wonderful boat crew who had no small part to play in the success of this trip. Back in my Brisbane home, I only have to close my eyes to see big schools of fish of all colours and shapes, and once again I am swimming along the inevitable line of transect tapes. Thanks to the expert knowledge of Dr. Maria Beger, who knows all fish by first (and second) name, I have been able to add Indian Ocean fish species to the repertoire of Pacific species I can identify.


Looking at the numbers in our spreadsheet, it seems hard to believe that we counted a total of 22,668 fish belonging to 224 species. We visited 20 sites, swam 6km defying (almost) all currents and deployed 5kms of transect tape for in situ as well as SVII based fish counts. Based on these numbers, I feel I should have lost some weight, and I blame the chefs and their beautiful food that this in fact did not happen!



A novel way to survey


The aim of our part of the mission was to assess fish diversity, abundance and species richness in the Maldives, based on traditional belt transect survey techniques.  At each site, we marked the area we assessed with transect tapes so that the SVII team could fly over the exact same area. Comparison of our in situ measurements can then be compared with fish data extracted from SVII imagery and thus help establish the Catlin Seaview Survey as a novel and fast way of conducting fish surveys.


During our time in the field, we had the opportunity to work with the Maldives Marine Research Centre (MRC) as well as with the International Union for Conservation of Nature (IUCN). We learned that the local reef fisheries mostly targets groupers as well as small fish, such as some triggerfish and fusiliers, which are used as bait fish for the tuna fishery. We certainly noticed the general lack of large groupers at our survey sites and it remains to be determined whether baitfish numbers are also diminished in more heavily targeted areas and/or over time. We visited several MRC long time monitoring sites and plan to work with the MRC to compare our data with those collected in the past.   



Creating a comprehensive picture


While the field trip is completed, more exciting work lies ahead of us. Analysis of our data will show if there is a difference between sites heavily influenced by humans (land reclamation, population size, known fishing practices etc.) and sites which are more removed from such influences. Then, we will be able to combine data collected by all teams to create a comprehensive picture of the present condition of Maldivian reefs along this gradient of human influences.  Ultimately, we hope that through working with MRC and IUCN, our data will contribute to the planning and improvement of local conservation efforts to preserve these beautiful reefs for the future.