Zanzibar Shark Project Update 13/02/2013 – When tigers became makos

The excitement and anticipation of waiting for the Nungwi shark photos to see if there were great white sharks in Zanzibar ended in slight disappointment. The shark data sheets labelled white sharks turned out to be silky sharks, whilst those labelled tiger sharks were actually shortfin mako sharks. How a shortfin mako could be mistaken for a tiger shark, I haven’t got a clue! Of the 68 sharks caught in Nungwi from September to December 2012 there were: 27 shortfin makos, 14 smooth hammerheads, 8 scalloped hammerheads, 3 great hammerheads, 6 silky sharks, 3 pelagic threshers, 2 bigeye threshers, 1 white-tailed dogfish, 1 bignose shark, 1 bigeye sixgill shark, 1 blacktip shark and 1 actual tiger shark. Even though there were no white sharks and not as many tigers found as I had hoped for, the fact that shortfin mako and hammerhead sharks were present in large numbers mean that I can focus on these species groups for my dissertation.

Mako shark

Hammerhead shark

Meanwhile the system of informing myself and the research of any sharks caught here in Kizimkazi-Dimbani fish market was not working as well as I had hoped. However after discussion with Mr Pandu there was an immediate improvement. The morning after our discussion I was informed of a large catch of 11 sharks, doubling my shark total in Dimbani in one morning! The sharks were all identified as white-tailed dogfish.

Now that we have the communication sorted, I am waiting eagerly for the month of March, when shark catches are reported to be quite high in the area and catches of 11 sharks every morning may become a regular occurrence! Large numbers of sharks are obviously welcome for the study but also a concern regarding the status of the species caught. We hope that the studies now conducted will provide data for an initial shark assessment and also indicate where more research may be needed.

Tutaonana badye (see you later),

William Jolly

Newcastle University

Shark project, Zanzibar

Zanzibar Shark Project – The beginning

Zanzibar Shark Project – The beginning

The Zanzibar Shark Project was initiated in July 2012 by asking local collaborators to assist in collection of data on landed sharks in two villages, Kizimkazi-Dimbani (where we live) in the south and Nungwi in the north of Zanzibar. We provided data forms, tape measure, sample bags and a camera to record information on the sharks caught in the local fisheries.

When we arrived here in Zanzibar we met with Mr Pandu and Mr Chupe who covers the areas in the south and north, respectively. We received data on 9 sharks from the south collected between September and November 2012 (including bull, scalloped hammerhead , bronze whaler and bigeye sixgill shark). We used the photographs and identification keys to match photos to species without much problem.  It was slightly disappointing to find the catch rate low in the south, as there is very little to go on to establish what species are present.

Hammerhead shark

Bull shark

The data received from the north were more encouraging. We received records from 68 sharks caught off Nungwi. The data forms indicate that tiger and hammerhead sharks are the dominant catches in the area with some, as of yet, unidentified sharks and the possibility of great whites. All species will be confirmed with the shark identification key once we have downloaded the photos from the camera that Mr Chupe has up in Nungwi.

Shark data form

As my original proposal is based upon hammerheads and considerable background research went into this group of species before leaving for Zanzibar, this is the sort of shark data I’d been hoping for. The possibility of finding juvenile great whites is also very exciting given that this species is not normally found this close to the equator but the sharks must of course be properly identified first before any conclusions are drawn.

We have now provided with additional sampling kits including scales to weigh the landed sharks. We are also adding a third sampling location at the fish market in Stone town (capital of Zanzibar) where sharks from most other areas around Zanzibar are marketed. Shark data forms, plastic vials for genetic material and glass vials for stable isotope analysis have been sent to the fish market in the hope that samples can be obtained.

Tutaonana badye (see you later),

William Jolly
Shark project, Zanzibar
Newcastle University