Jellyfish hamper fishing operations off Pakistan coast

KARACHI: Fishing activities off the coasts of Balochistan and Sindh have been severely affected over the last two weeks by unprecedented jelly fish blooms, forcing many fishermen to move their activities to other areas mainly towards Somniani Bay and adjacent areas while many others have completely ceased their fishing operations.

The presence of mauve stinger or Pelagia noctiluca or ‘Langara’ in Sindhi and ‘Mus’ in Balochi has the ability to glow in the dark but has no commercial value while the mammoth jellyfish commonly called mushroom jellyfish (scientifically Rhopilema hispidium) and locally referred to as the ‘Jungli Langara’ are venomous jellyfish. The WWF has estimated the population to be over 150 stingers per cubic meter.

The Pelagia noctiluca is well known for its beautiful luminescence and glow in the night when disturbed or moved by wave action. Fishermen have reported witnessing it’s signature glow off the coasts of Sindh and Balochistan for the last two weeks spread over an area of 250 square kilometers.

Due to the increased presence, fishermen have complained of the jelly fish clogging their nets. In addition to hampering fishing activities, removing the jelly fish from nets is a cumbersome task and exposes the fishermen to the venomous sting that results in pain and inflammation that lasts for over 24 hours.

Affecting the Catch

Fishermen have reported a sudden decrease in their catch of some of the prime fish varieties, attributing the decrease to the presence of the jelly fish.

The WWF says previous blooms observed over the past years lasted between 10 to 20 days.

Unlike the Pelagius noctiluca, the Rhopilema hispdium does have commercial value and is harvested in creek areas of Sindh according to the WWF. These jellyfish are harvested for export purposes and Pakistan exports dried jellyfish to the tune of 2500 metric tons per year.

Besides the Rhopilema hispidum, the Catostylus perezi is also processed and exported. A record export of 4,000 metric tons was exported during 2005-2007 to Vietnam and China.

The jelly fish industry in Pakistan employs over 10,000 people and makes for extra income for smaller fisheries with main processing plants located in Ibrahim Hyderi, Rehri and Keti Bundar in Sindh and Damb along the Balochistan coast.

Sources add, that smaller blooms are witnessed frequently and do not threaten fishing operations.

Disruptions not limited to fishing activities

WWF’s Technical Advisor for Marine Fisheries, Muhammed Moazzam says the frequency of jelly fish blooms is increasing in Pakistan and the increased size of the blooms not only disrupt fishing activities but also clog cooling water intakes at power plants causing power shutdowns.

The increased jellyfish blooms also have an adverse impact on populations of commercially important fish varieties, as the jellyfish consume the plankton, eggs and larvae and juveniles as well. Experts say the impact of this not only depletes food resources of fish but even larger mammals such as whales.

Natural Cycle or Man to blame

Despite all the circumstantial evidence, scientists say more research is needed before they can determine conclusively if the increasing jellyfish blooms are the result of natural cycles of a result of human impacts on the environment.

While experts admit they do not fully understand the reasons for the sudden increase in jellyfish populations, it is generally believed that warmer sea temperatures favour most jellyfish species to swell in numbers. It is also believed that overfishing which eliminates the jellyfish’s natural predators and competition also plays an important role. Meanwhile another theory suggests the discharge of untreated sewage into the sea also increases the nutrients in the coastal waters that could play a role in making the area favourable for jellyfish to thrive in, due to the increased nutrients.

Until more research is done to understand the reasons behind increasing jellyfish blooms, scientists cannot conclude why this phenomenon is being witnessed more frequently.