Karachi: Described as an intelligent and inquisitive marine mammal, dolphins are loved all over the world for their playful behaviour. Sadly, this beautiful creature is facing a battle for its survival in our sea waters.
A recent study conducted by the World Wide Fund for Nature-Pakistan (WWF-P) shows that a staggering number of dolphins are killed every year as bycatch, after being entrapped in tuna gillnets. The estimated annual mortality figure for dolphins is 12,000.
Unlike other species, dolphins have no commercial value. Experts believe that the fast disappearance of this top predator from marine waters would have a direct bearing on our fragile ecosystem.
Titled ‘An Assessment of Cetacean Mortality in the Tuna Fisheries of Pakistan’, the study was conducted by director WWF-P (Sindh region) Rab Nawaz and Mohammad Moazzam Khan, former director of the marine fisheries department and presently serving as the technical adviser on marine fisheries with WWF-P. It was funded by the Australian Marine Mammal Centre.
The year-long data was collected in 2012 through observers posted on four tuna gillnet vessels as well as daily monitoring of tuna gillnetters at the Karachi fish harbour, the main landing centre for tuna. The data was made available online in 2014.
According to the study, Pakistan is one of the few countries where gillnet is being used for catching different species of tuna. The report discovered yellowfin tuna as the main tuna species being reported in commercial catches.
“Although eight species of tuna are known from Pakistan, only six were found to be common at commercial landing during the study. The data collected from Karachi fish harbour revealed that yellowfin tuna was the most commonly occurring species contributing about 45pc in the total commercial landing.
“Longtail tuna contributed about 25pc, followed by kawakawa 19pc, frigate tuna 6pc, skipjack tuna only 5pc whereas bullet tuna less than 1pc,” it says.
A small peak of tuna landing was observed during the months of September and December while tuna landing declined in June and July as almost all tuna gillnet vessels stopped their operations due to the intensive monsoon.
All tuna smuggled
There seems to be disparity between the data revealed by the government and the one found in the present study. The report points out that while the total tuna landing (along with the bycatch) was estimated to be around 47,000 tonnes from Sindh during the present survey, official statistics shows it at 32,156 tonnes.
This difference in data, according to the report, is mainly due to the inclusion of tuna catches that are transshipped at high seas.
It is important to mention here that tuna is one of the world’s favourite and highly-priced fish. Improper handling of catch and a lack of storage facilities on local fishing vessels make it a non-consumable item in the city market. However, the species, caught in large numbers in Pakistan, is smuggled to Iran which leaves a small portion of total catch for export.
High bycatch
According to the study, the gillnet tuna operation yields high bycatch, as large numbers of different fish species and other animals are caught by gillnet vessels.
Data reveals that about 30pc of the catch of tuna gillnet vessels consisted of bycatch which landed at the Karachi fish harbour. The data recorded by observers, however, showed that the contribution was actually 40pc (the disparity is on account of the same reasons as explained above).
Fish more prominently found in bycatch include Indo-Pacific sailfish and common dolphinfish followed by sharks and marlins. Other fish species included unicorn leatherjacket, rough triggerfish, narrow-barred Spanish mackerel, wahoo, great barracuda, rainbow runner and sickle pomfret, which, the study says, were regularly caught by tuna gillnetters.
These bycatch species, the study says, are commercially important and sometimes fetch very high prices. As shark species fetch high prices in the local market too, therefore, they are retained and landed at fish harbours.
“The Indian Ocean Tuna Commission to which Pakistan is a signatory has issued a number of resolutions on shark catch and requires the nations to record incidental catches of sharks, to release live thresher sharks and conduct research to take appropriate measures on scientific data etc. However, resolutions are not being implemented in Pakistan,” the study reveals.
Tuna vessels, it points out, occasionally also catch a number of demersal species whose names are not included in the report.
According to the study, about 12,000 dolphins are annually killed in tuna gillnet operations along the coast of Pakistan. A single tuna vessel, it is estimated, kills about 24 dolphins a year during its operations (there are about 500 tuna vessels operating in Pakistani waters).
“It was observed that maximum mortality of dolphins occurs during September-November when a total of 3,300 dolphins are killed in the tuna gillnet operation. This may be attributed to operation of tuna gillnet vessels in comparatively offshore waters. The other peak time of dolphin mortality was found between January and March,” it says.
Among the dolphins species, Indo-Pacific humpback dolphin, bottlenose dolphin, spinner dolphin, pantropical spotted dolphin, long-beaked common dolphin, Risso’s dolphin, striped dolphin and rough-tooth dolphin were killed during the tuna gillnet operation.
It was observed that all enmeshed dolphins were killed immediately because they couldn’t come to the surface to breathe. In no case was a dolphin found alive in gillnets. Fishermen have reported heavy depredation of dolphins on enmeshed species especially tuna.
No enmeshment of finless porpoise was observed that, the study says, was mainly because the species is found in shallow coastal waters. No mortality of baleen whales was observed and with the exception of one dwarf sperm whale, no mortality of toothed whales was recorded.
The study recorded only one case of a toothed whale getting trapped and killed.
Entrapped turtles
Marine turtles, according to the study, get entrapped frequently in the tuna gillnets operation in the coastal and offshore waters of Pakistan. The data collected during the project reveals that olive Ridley turtle is the most dominating turtle species entrapped in Pakistan followed by green turtle.
“It is noteworthy that no nesting or dead olive Ridley turtle has been recorded from Pakistan over the last 11 years but still it is the most dominating turtle species enmeshed in tuna gillnets. A large population of this turtle has been observed in the offshore waters of Pakistan.
“Population of enmeshed olive Ridely turtles in the tuna gillnet is estimated to be about 31,000. It is speculated that this population might be nesting in neighbouring countries. Turtles were seldom found to be dead when heaved from the sea along with gillnet during the study,” it says.
Citing some estimates, it points out that about 200 to 300 turtles, mainly olive Ridley turtles, are killed every year in the tuna gillnet operation along Pakistan coast. Their death occurs mainly because of their mishandling on board or crude way of throwing them back into the sea.
The study suggests appropriate management measures including a ban on new entries in tuna gillnet fishing, compliance to the United Nations General Assembly resolutions restricting gillnet length to 2.5km, conversion of gillnetting fleet to long-lining, declaration of marine protected areas and establishment of a regular database on the mortality of turtle and cetaceans.
The use of long gillnets, from five to 30km is the major factor that causes trapping of dolphins and their death, experts say.
