A Potential New Dimension for the SVII: Fish

Image: A school of Blackfin Barracuda photographed by Ken Marks of the Living Oceans Foundation


I am excited to be viewing the Catlin Seaview Survey team in action for the very first time. We are on a trip with the Living Oceans Foundation to the Solomon Islands and I have quickly realized that what I thought was a straightforward project – taking pictures of the reefs worldwide - is a highly complex and challenging mission. It starts with bringing enormous numbers of heavy boxes full of delicate electronics, lasers and underwater scooters (which look just like bombs on the x-ray machine) into another country. Within minutes of arriving onboard The Golden Shadow, our room is filled with cables and blinking lights.  Hours of careful cleaning and testing are required before the impressive looking SVII underwater camera and scooter can be assembled. The end product looks like a giant metal dragonfly ready to fly over the reef.



Looking at fish diversity and abundance


Our mission on this trip is not only to document the current condition of the reefs around the Solomon Islands but also to look at fish diversity and abundance. We are evaluating the suitability of the SVII imagery to detect fish abundance in comparison with standard fish monitoring methods.  If we find a good correspondence between fish seen in the SVII imagery and fish seen by human observers along the same transects, we can add another dimension to the Catlin Seaview Survey: fish.   



Measuring the size of detected fish


We are also attempting to measure the size of the fish detected in the SVII imagery.  It is impossible to extract fish size data from the images without knowledge of the distance between the object and the camera.  At the beginning of a standard transect we place objects of known dimensions along the transect tapes at known distances from the camera system in an attempt to identify fish size.   


Adding fish data to the Catlin Seaview Survey will allow us to evaluate the interconnection between fish population and reef health.  Fish diversity and abundance is highest on healthy reefs protected from excessive human influence.



A community-based approach for food security


Interestingly, the Solomon Islands have a community-based approach to resource and fisheries management. While a national and regional legislation exists, communities determine areas that can be fished and how much can be extracted. No-take zones are also determined by the communities, largely to ensure food security.


In the first few days of counting fish the list of species identified has grown to well over 200. The most amazing thing to me is that not a single dive goes by without a ‘herd’ of grazing Bumphead Parrotfish going past our survey sites.