Pre-existing basking shark fisheries have been historically characterised by a boom and bust relationship. This has given rise to the belief that basking sharks have a low annual population uptake, estimated at 2- 10% (Compagno, 1984). However, a number of studies have since attempted to examine the relationship between basking shark abundance and long-term zooplankton decline. This correlation is reported to be a contributing factor in the sudden changes in localised basking shark populations over short periods of time (Sims, 2000).

 

In Irish waters, it is suggested that basking shark target fisheries overexploited the localised basking shark population in the 1950’s and 60’s, leading to a collapse in the target fishing of basking sharks (McNally 1976, Sims & Reid 2002). However, there are currently no population estimates for basking sharks in Ireland, largely because no measurable data sets exist to indicate population expansion or contraction trends. There is also no research on the behavioural/feeding habits of basking sharks within Irish coastal waters, their spatial and temporal distributions or the major factors influencing these practices (Berrow, S.D., 2008, Speedie, 2003). The work of the IBSP and the IBSSG is attempting to address this knowledge gap (see out "Projects" page).