Oceans/fishermen living: 'Jellyfish bloom dynamics can help understand impact of climate change'

On the eve of International Jellyfish Day, experts said that the scientific dynamics of jellyfish bloom can help understand the impacts of climate change on the marine environment and livelihoods of coastal communities. Nations across the world mark International Jellyfish Day on Nov 3 every year, signifying the spectacular marine species. The WWF-Pakistan believes the scientific dynamics of jellyfish bloom can be helpful in finding the impacts of global weather change on oceans and resultantly on fishermen living.
An important component of the pelagic ecosystem, jellyfish blooms have been reported to indicate the introduction of species in marine waters, over-fishing, eutrophication and most importantly, climate change. It is unclear whether the increase in biomass of gelatinous jellyfishes is caused by anthropogenic changes or is a manifestation of natural ecosystem variability.
Jellyfish are mainly free-swimming marine animals with umbrella-shaped bells and trailing tentacles which may have stings. When conditions are favourable, jellyfish can form vast swarms or blooms. The name jellyfish is given to the certain gelatinous members of the phylum Cnidaria.
According to Muhammad Moazzam Khan, Technical Adviser (Marine Fisheries), WWF-Pakistan, eutrophication, overfishing, habitat modification and climate change are all possible contributory factors that facilitate proliferation of jellyfish blooms. To determine the causes of bloom formation, WWF-Pakistan is closely observing their dynamics. He said jellyfish fisheries play an important role in the livelihood of fisher communities along Pakistan's coast.
By considering its bloom status, location and production, the coastal communities in Miani Hor manage this fishery in an organized way and WWF-Pakistan works closely with these communities to ensure sustainable management of jellyfish and improve livelihood options. "We are also trying to develop a similar management regime for jellyfish fisheries in Sindh,' he added.
It is believed that jellyfish blooms affect commercial fisheries by choking and damaging fishing gear, and sometimes clog the cooling systems of power and desalination plants, which draw water from the sea. A major bloom of jellyfish Crambionella orsini was observed in the Arabian Sea, including Yemen, Oman, Iran and Pakistan in May 2002 and August 2003. In addition, a massive jellyfish bloom occurred along the coast of Pakistan in December 2002.
The WWF-Pakistan reported a major mushroom jellyfish (Rhopilema hispidium) bloom from the offshore waters near Swatch Area in December 2016. It is reported that a large number of Crambionella orsini have resulted in reduction of catch of commercial fishing operations along the Pakistan coast. It also caused massive clogging of nets and interrupted the operation of seawater cooling systems of power plants and ships. A number of smaller blooms of jellyfish frequently occur in Pakistan but these do not pose any threat to fishing and other such operations.
Jellyfish are eaten as a delicacy in some Asian countries. These are also commercially harvested from Pakistani waters for export. It is reported that about 2,500 m. tons of dried jellyfish, mainly Rhopilema hispidum and Catostylus perezi is exported annually. The highest jellyfish export took place during 2005 to 2007 when about 4,000m tons of jellyfish products were annually sent to China and Vietnam. Jellyfish fisheries in Pakistan provide an extra source of income to small scale fisheries. It is estimated that more than 10,000 people are engaged in jellyfish fisheries in the country.