Take, take, takeOverfishing and Overexploitation
‘Exploitation of the seas’ is a frightening term, however, many communities rely on seafood to sustain livelihoods and feed their families, and thus overfishing of fish stocks must be considered carefully.
Overfishing and overexploitation are terms that mean a fish stock is exploited in a non-sustainable way; in other words, if current exploitation rates were to continue, fish stocks would collapse and food security would be threatened. In order to conserve fish stocks effectively and maintain food security and economical stability, the goal is to ‘fully exploit’ stocks (Pers, comms. Shiffman 2021). This means that the maximum is yielded from fish stocks in a sustainable manner, and fish stocks will continue to stay high and profitable well into the future, without harming ecological balance.
This is easier said than done! One of the main threats marine ecosystem function faces today is overfishing because it is not simple nor easy to manage the needs of people and maintain a healthy fish stock. This is especially true in many contexts where knowledge gaps persist in the life history and ecology of commercial fish species, and illegal fishing practices mean that a lot of captures and discards go unreported (Barrett et al., 2018).
Exploitation for trade is one of the greatest threats for many species, especially marine species thought to have spiritual or medicinal properties like the seahorse. Despite all species of seahorse being identified as on the decline by the International Union for the Conservation of Nature (IUCN), seahorses are listed under Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). This designation allows exports of specimens that are sourced sustainably and legally according to CITES rules and regulations. However, since the designation, a lot of the main exporting countries of dried seahorse have banned trade entirely or are under export suspensions enforced by CITES. One of these countries is Thailand, with the export of dried seahorse being suspended in January of 2016.
Good news, right?…
Maybe not. Despite this ban being in place, surveys of seahorse traders in Hong Kong revealed almost all (95%) of dried seahorse and seahorse products were being imported from countries where trade has been banned. One of those countries is Thailand.
So, what does this mean for the seahorse? We can no longer regulate their trade and it is likely that without regulation or control seahorses are being harvested in non-discriminate methods such as bottom trawls. These methods not only destroy the seabed but everything on it too, such as corals, rays, benthic fish and often turtles.
Seahorses are particularly vulnerable due to their life history and ecology, characterized by strong fidelity to mates and small home ranges, as well as low mobility, parental care given to their young and low fecundity. This all means that the seahorse can’t withstand the current levels of exploitation and if we don’t manage trade soon, we could lose seahorses forever.
Big knowledge gaps remain in the target species of Thai fisheries in the Gulf of Thailand and the Andaman Sea, so it is difficult to really understand exactly which commercial species are at risk. However, what we can work from is the estimation of the proportions of the types of fishing methods used within Thai waters and typically what species they target and exploit. Studies have revealed that since its introduction to Thailand in the 1960s, trawling harvested approximately 70% of catch – and this is where sharks come in.
Trawling is a highly indiscriminate form of fishing and results in the catch of huge quantities of non-target species, namely sharks. Like many places in the world, Thailand has experienced great and rapid declines in shark numbers in recent decades, and despite sharks not listed as a target species of Thai fisheries, Thailand is still one of the greatest exporters of shark fin.
Unfortunately, there is no official landings data for sharks in Thailand that differentiates species, so it is hard to tell exactly which species are at the highest risk. We can infer from life histories of certain sharks that they may be experiencing great declines, for example, the bull shark, reported by an independent study to make up 48% of shark biomass landed in Ranong province of Thailand over a period of 1 year, is long-lived and has few young, making them less resilient as a species to overexploitation.
Tuna are an incredibly valuable group of species making up an estimated 8% of all seafood products in markets worldwide. As of 2018, 37% of tuna stocks globally were fully exploited and 33.5% already overexploited.
Yellowfin tuna (YFT) has a worldwide distribution, easily accessible by all but mainly fished in the tropics. Being large, powerful fish, YFT need to make huge migrations all over the world to forage for food and support their growth and metabolism. This species is usually caught using purse seine nets and other fish aggregation devices (FADs), which are indiscriminate and often catch dolphins and other fish too. YFT can also be caught by line and pole which is the most sustainable method, and longlining, another non-targeted method that often catches sharks as bycatch.
One of the most recent changes to YFT fisheries leading to reduced effort and therefore catch has actually been put down to piracy in the Indian ocean forcing vessels to stay home and vessels still operating to have extra expensive security measures in place such as working in pairs or having military personnel on board.
In order to curb YFT overfishing, conservation measures have been imposed by FAO Fisheries Department under the Convention on the Law of the Sea and two-to-three-month closures of fisheries have been proposed all over the world to reduce catch. YFT fishing is never going to completely cease due to its value and importance as a human food source, however, we can choose to eat less in our day-to-day lives as well as choose sources that use sustainable practices such as rod and line fishing. If in doubt, eat less, eat local and avoid yellowfin!
You can do your bit to curb the effect of overfishing and overexploitation by being a responsible consumer and reading about which fish species can be enjoyed sustainably and those to be avoided in our sustainable seafood guide.