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First Year of Fish Surveying Complete

It has now been just over a year since we started our fish survey programme in the Kwanini Marine Protected Area (KMPA) and following many hours of video analysis we have our first provisional results! Read on to find out how many fish have been counted within the protected area and who the key residents are.

It has now been just over a year since the Kwanini Marine Protected Area (KMPA) fish surveys started. These surveys were a first of their kind in this area as scientific surveys of Pemba’s fish are few and far between. Additionally, the Kwanini Foundation are using a relatively new survey technique known as diver-operated stereo-video. This technique uses two mounted cameras, and the footage has the advantage of providing highly accurate estimates of fish abundance, diversity and body size when compared to conventional fish survey techniques. This method has not been used on Pemba’s reefs before and has limited use throughout East Africa. You can find out more about the survey method in our Fish Surveys Project Page.

The fish surveys are being undertaken with the goal of establishing baseline data for fish abundance and diversity within the KMPA, monitoring any improvements or deterioration of fish populations, and providing supplementary data alongside Kwanini’s reef restoration and monitoring programme.

The first surveys were completed at the end of July 2019 with additional surveys completed in October 2019 and January 2020. Unfortunately, due to the COVID-19 pandemic we were unable to undertake the fourth round of surveys in April 2020, however we will resume our normal survey programme as soon as international travel restrictions are lifted.

The fish surveys involve swimming a 50 meter transect along the reef with the stereo-video equipment set up to film all fish in the area. Twenty-eight of these 50 meter transects were completed during each survey period, with the exception of January 2020, when we were only able to complete 26 transects due to unusually poor visibility in the shallower waters. The surveys focus on two areas of the reef at two depth ranges; the KMPA and buffer zones to the north and south of the KMPA. Deep surveys are classed as between 14 and 16 meters and shallow surveys between depths of 6 and 8 meters.
Once each survey period is completed, fish counts and identification are undertaken. Our analysis so far indicates that throughout the three survey periods, a total of 48,348 fish were recorded. In July 2019, a total of 17,308 fish were counted with 19,088 and 11,952 fish counted in October 2019 and January 2020 respectively. We have also identified an amazing 168 individual species.

During the video analysis a list of key species has been compiled and includes species of commercial and ecological importance. Fish from the families Anthiinae (Anthias) and Pomacentridae (Damselfish and Clownfish) were the most common during all survey seasons. If you have snorkelled or dived on the reefs of the KMPA you are likely to have seen the huge schools of colourful Anthias, which due to their sheer numbers cannot be overlooked.
By producing a list of key species, this allows us to conduct a targeted analysis of species which are indicators of reef health or fishing pressure. For example, we are monitoring populations of butterflyfish as several species feed on coral and their presence or absence can be an indicator of changes in coral reef health. On the other hand, Emperors are considered a commercially important species and their numbers can indicate population recovery when the threat of fishing is removed through the protection offered by the KMPA. Other key species include groupers, triggerfish, porcupinefish, goatfish and pufferfish.
At present, it is not possible to draw accurate conclusions on the improvement or deteriorations of fish populations within the KMPA and surrounding area. This is due to a few different factors, including the lack of historical data on fish in, or near, this area and the seasonal changes in fish populations and diversity. However, the Kwanini Foundation hopes to build on this fish data which will allow for seasonal and annual comparisons between data sets.

The data gathered so far suggests that the total number of fish across all three survey periods is consistently higher within the KMPA, compared to the buffer zone sites. This is an important observation which supports the continued protection of KMPA as a refuge for fish.

Moving forward, we will continue monitoring fish populations and diversity.

Whilst the locations will remain unchanged, surveys will be reduced from four times a year to twice a year, to tie in with other monitoring programmes such as coral and invertebrate surveys.
The above images are screenshots from video footage taken during the surveys that show the stark contrast in fish numbers inside the KMPA (left) compared with the buffer zones (right).