Basking sharks "staging comeback" back in UK waters
July 23 2012 Lewis Smith
A basking shark feeding on plankton
Basking sharks, the world’s second largest fish, are thought to be mounting a recovery in UK waters following the end of commercial hunting.
Sightings have not only risen in number over the last 20 years but the size of the individual sharks seen has increased, a classic sign of population recovery.
More than 81,000 basking sharks were caught in the North East Atlantic from 1952 to 2004 but they are now widely protected. They were sought mostly for their large livers which are high in oil used for cosmetics and dietary supplements, or in dishes such as shark fin soup.
Large-scale commercial exploitation of the shark mostly ended in UK waters in 1953 but it was renewed off Scotland from 1982 to 1994. It was ended by Iceland in 1975 and by Norway in 2000.
Legal protection for the basking shark, classified as vulnerable by the International Union for the Conservation of Nature (IUCN) was introduced by the UK in 1998 Scientists analysing sightings reported by the public and researchers in the last 20 years now believe that the basking shark is showing signs of recovery.
The increased rate of sightings, while encouraging, is not regarded by researchers as strong evidence of a population recovery because it could be affected by other factors, such as greater awareness by the public of reporting schemes.
However, the increased size of the specimens seen – the public reported seeing more medium-sized sharks while researchers on shark-spotting boats recorded more large sharks – is a typical indicator of a larger population. Reliable estimates of the number of basking sharks have, so far, been impossible.
Basking sharks are slow to recover from population declines because they only produce small numbers of young each year and are not thought to breed until they are at least 5 metres (16.4 feet) long and are 12 to 16 years old. They can reach 10 metres long and more than 50 years in age. The only species of fish bigger than the basking shark is the whale shark.
Analysis of the summer sightings was described as “the most comprehensive ever” and was carried out by the University of Exeter, the Marine Conservation Society, the Cornwall Wildlife Trust and Wave Action. The results are published in the journal Marine Ecology Progress Series.
“Our research shows that basking sharks could be recovering from the extensive hunting that took place in the 20th century,” said Professor Brendan Godley of the University of Exeter.
“Anyone who has had the experience of seeing a basking shark from our coastline will know what awe-inspiring creatures they are and our research suggests that more of us may be fortunate enough to see them in the future.”
Ruth Williams, of the Cornwall Wildlife Trust said the study illustrated the importance of data collected by the public and added: “It is hugely encouraging to see the positive trend in numbers of basking sharks in our waters.”
Dr Jean Luc Solandt, of the Marine Conservation Society, said: “These exciting results show that long-term protection for basking sharks seems to be paying off – great news to celebrate the 25th anniversary of MCS Basking Shark Watch, which has been supported by thousands of people across the UK. It is only through public participation that we can see this positive change - citizen science works!
“The industrial demand for basking shark oil is now over, but the large basking shark gatherings we see each summer in our seas are proving to be popular wildlife spectacles. This conservation success means that these harmless giants will be here to be enjoyed by generations to come.”
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