MUMBAI: The first comprehensive marine fish stock assessment for India reveals a surprisingly positive picture: 91.1% of 135 fish stocks evaluated in 2022 were found to be "healthy".

The two-year break in fishing activity caused by the pandemic may have played a big role, experts said.Out of the 135 stocks, 86.7% were found to be sustainable - meaning that they had enough population to support maximum sustainable yields.

Sustainable stocks included certain varieties of dolphinfish, eels, lizardfish and snappers, as well as pomfret."This doesn't mean these stocks can be fished more and more without consequences," cautioned Shoba Joe Kizhakudan, principal scientist with the Central Marine Fisheries Research Institute (CMFRI), which did the evaluation.

"(While) 91% seems like a good figure, it is based on biological status at the moment," she added, noting that fishing pressures can easily change the picture in subsequent years.Regionally, the southeast coast had the highest percentage of healthy stocks (97.4%) in 2022, followed by the southwest (92.7%), the northeast (87.5%), and the northwest was at the lowest at 83.8%.Overall, the assessment found 8.2% of stocks to be overfished, including varieties of croakers, catfish, groupers, sharks, and lobsters, and about 4.4% were tending to be overfished.

An overfished stock is one whose biomass or population is too small and fishing pressure too high to support maximum sustainable yields.

However, none of the stocks assessed had collapsed - that is when a population has fallen to such a low level that it does not recover within a certain time.One stock, that of squid in the northwest coast, was found to be rebuilding after collapse.

This was unsurprising, scientists said, since squids are short-lived creatures whose populations can rise and drop sharply in natural cycles.

"It's the slow-growing large fish like sharks you have to worry about," said Rajan Kumar, a scientist at CMFRI Veraval.The Covid-19 pandemic seems to have helped the health of fish stocks.

Although there is not enough data from those years, a comparison of pre- and post-pandemic figures suggests that the break in fishing may have played a role, said Kizhakudan.

The year before the pandemic, 2019, also had lower fishing activity on the northwest coast due to cyclone activity, noted Kumar, who also worked on the assessment.The catch of pomfret, for instance, was on the decline before the pandemic, with much concern about overfishing of juveniles that could affect the population health.

But several years of reduced fishing activity helped push pomfret "just over the threshold" into the healthy category in 2022, he said."We will not be surprised if there is a drop in the number of (healthy stocks) in subsequent assessments," he added.As the first assessment of its kind, the study was limited to 70 species across four coastal regions - north and south, west and east - as well as Lakshadweep, and included 49 finfish and 21 shellfish.

Subsequent reports will need to look at many more fish, including such valuables ones as hilsa.

Annual stock assessments are a standard tool of fisheries management in industrialised fishing regions such as Europe and the USA.

Such reports can be important in an era of increasing demand for sustainably sourced fish.

Although CMFRI says its report cannot be used as a certification of sustainability, the evaluation could help exporters seeking to show their products are sustainably produced, experts said.For stocks found to be overfished, the CMFRI report recommends measures such as imposing a minimum legal size and changing the mesh size of nets to reduce catch of juveniles and bycatch.

For species like sharks and lobsters, incentives to fishermen to release them back into the sea need to be given, experts said.