OUR PROJECT BOARD
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The true inspiration of Fishers4Science is the ongoing Fisher-Researcher Collaboration that is central to all the work we do at F4S. The concept behind this initiative is to reduce fishing pressure on sharks by working with shark fishers to diversify their income. We began strategically working with them primarily during the shark fishing season to lessen their fishing efforts and incorporate tagging as a way to reduce the time fishers spent targeting sharks. It has been a massive success and now we partner with shark fishers to conduct research at all times of the year. This initiative is behind every project we do and the benefits of this collaboration is 3-fold: 1.) it collects important information about the sharks and shark fishery here in Belize, 2.) it reduces fishing pressure, and 3.) it helps support local fishers by diversifying their income and contributing to job security.
Coastal Longline Survey
Anal Fin Monitoring Program
The anal fin monitoring program is a user-friendly program designed to aid managers in the Western Caribbean region to monitor and assess their shark fishery or bycatch of sharks in a cost-effective way. It works well in data-poor environments as it only requires the collection of a secondary fin to successfully reconstruct the catch. The anal fin is first visually identified to species level, the number of anal fins reflects the number of individuals caught for each species elucidating species compositon of the catch, and lastly linear regression is applied to the measurement of the fin to regress the length of the animal in which the fin came from. Though this program has been tailored to monitor common shark species in the western Caribbean region this program has broader implications as with few modifications it can be adopted in other regions. This is an ongoing, collaborative study that is expanding and continually developing new species-specific regression equations and describing new anal fins in the published Anal Fin Guide.
Goal: overcome the challenges of data collection to improve monitoring of shark landings.
Monitoring a shark fishery can be very challenging, especially in a developing nation with limited resources. An additional adversity Belize must overcome is there is no central landing site; rather, shark fishers work up their catch at different cayes or camps throughout the country, making it very difficult for managers to be in all places at once. This can make it very challenging to track landings or be able to assess the fishery for sustainability. There are seemingly basic, fundamental data that are required to be able to assess a fishery for sustainability: species, quantity, and size. But in a country where resources are limited, fishers are dispersed, and prioritizing processing the catch can leave fisher logbooks incomplete, it can be quite challenging to collect this basic information.
This is where the anal fins come in..
Nearly all species of shark have an anal fin. It is a single fin located on the underside of the shark and is the last fin before the caudal fin (tail). This fin has little to no value in the trade and is considered a secondary fin, meaning it is not like the dorsal fin (along the back), or the pectoral fins (airplane wings) of a shark, which can be highly valued in the fin trade. So how does this fin help us monitor a shark fishery? Well, after conducting a pilot study where a subset of fishers were asked to submit the anal fin from each shark they landed, it was found that anal fins were as unique as the sharks they come from. Nearly all fins could be visually identified to species level, with few exceptions. After seeing the success and potential of this the Belize Fisheries Department made submitting anal fins a condition of license renewal for shark fishers. This method was then upscaled nationwide and applied to a full shark fishing season. Being able to identify anal fins in this way gave us two of the three fundamental pieces of data we needed: species and quantity. By knowing what species each fin came from we understood what species were being landed and by counting the anal fins we were able to determine how many of each species was being landed.
Still missing size…
With knowing what species and how many were being landed, our last piece of the puzzle was to determine what size, in this case length, individuals were being caught. To do this we investigated the relationship between the anal fin width and the total length of the animal. This entailed going to different fisher’s camps to collect paired measurements; anal fin width and total length, from each shark. We established this relationship for the top four most commonly caught species in Belize; Caribbean reef, blacktip, sharpnose and bonnethead sharks. Using linear regression we obtained species-specific regression equations which we were able to apply to the widths of the anal fins submitted by fishers. With each species-specific equation, we are able to infer the total length of the animal in which the anal fin came from.
Scientists and managers are able to reconstruct the catch of the shark fishery with only the use of a fisher-contributed fin; the anal fin. With this fin we are able to deduce species composition (which species and how many individuals of each) and infer the lengths of the most commonly landed sharks.
As researchers and managers process the anal fins being submitted, a stock assessment for sustainability is on the horizon to determine if each shark species can handle the current level of fishing pressure. Check back here to to see these results in the coming months.
If you are interested in collaborating or implementing the Anal Fin Monitoring Program please email Fins4science@gmail.com. Below are resources on the method: