Excitingly, blacktip #2 was just a few hooks away, and so the process began again. This time we switched roles, allowing our international volunteers to gain valuable hands-on experience. It was at this point that the gentle drizzle turned into a torrential, tropical Bahamian downpour. Within a few minutes we were drenched and forced to come up with imaginative ways to record data in the logbook. A drink cooler that we call a ‘dry box’ doubled as a makeshift shelter.

We completed the ‘pit stop’ work-up on five more occasions that night, bringing our tally for the check to seven female blacktips that ranged in length from 1.2 to 1.82 metres. Happily, all these delicate sharks swam off vigorously when released and, despite our waterlogged exterior, the team was full of excited chatter on our return to the Shark Lab. ‘We cheated death’, ‘My favourite experience at the Shark Lab so far’ were just a few of the comments I heard as we tied up to the dock. Based on our long-term monitoring of Bimini’s populations of large sharks, we have come to expect higher catches of blacktips towards the end of the summer months, but seven on one check in extreme weather conditions was certainly an entry for the diary!

Due to the longevity of our research programme, the long-line survey has enabled us to investigate population trends for large coastal sharks over the long term. The main species in question – lemon, nurse, blacktip and tiger sharks – are abundant in the commercial shark long-line fisheries of the north-west Atlantic and our longitudinal study can contribute important regional data that are species-specific and will improve management of these species and ultimately their conservation. Furthermore, biological samples taken during surveys have contributed to our study of the genetic family tree, mating system and life history of the lemon shark, and have identified how blacktips captured in The Bahamas and the United States belong to different populations.

Our 30-year data-set is currently being scrutinised by University of Massachusetts Master’s student Alex Hansell in collaboration with former Shark Lab PhD candidate Dr Steve Kessel of Windsor University, Canada. They are assessing how the shark assemblage in Bimini’s environs has changed over time and how other factors, such as water temperature, lunar cycle, bait type or soak time, might influence our catches. Importantly, with this historical data-set we are able to examine long-term trends in shark abundance, which improves our understanding not only of natural population fluctuations, but also how they are disrupted by anthropogenic influences. This is particularly important for top predators that can exert controlling influences on the ecosystems they inhabit and may be susceptible to human-driven population declines. Finally, given the recent designation of The Bahamas as a shark sanctuary, it is hoped that in the future this study can be used as a benchmark against which a continued long-line survey will be measured to assess the effectiveness of the sanctuary in protecting regional shark populations.