Fish Evolution Due to Ocean Warming Threatens Indonesian Fishermen's Catches

Increasing ocean temperatures are driving genetic evolution in fish species, a process that, while potentially helping them adapt to climate change, is predicted to create future challenges for traditional fishermen and the fishing industry. Mohammad Mukhlis Kamal, an ichthyologist and lecturer at IPB University's Faculty of Fisheries and Marine Science, explains that climate change impacts fish through three main pathways: rising water temperatures, decreasing dissolved oxygen, and ocean acidification.

“

The combination of temperature, oxygen, and acidity creates stronger natural selection pressures on fish populations.

These environmental shifts influence fish metabolism, growth rates, and spawning seasons. Simultaneously, reduced dissolved oxygen puts a strain on species requiring more oxygen, particularly fast-swimming fish like tuna, skipjack, and mackerel. Ocean acidification can also affect the development of scales and bones in fish larvae. Kamal notes that the combination of these factors creates stronger natural selection pressures on fish populations.

While warmer waters may not significantly disrupt smaller fish, larger species with higher biomass are increasingly pressured. From a fisheries perspective, a smaller body size means a reduction in catch biomass. The evolutionary adaptation to environmental anomalies, resulting in smaller fish, also signifies fewer eggs produced. Consequently, the "recruitment", the entry of new individuals into fish populations, including those commonly caught by fishing vessels, may decline sharply. Kamal emphasizes that the sustainability of fisheries heavily relies on the population's ability to replace caught fish.

“

The sustainability of fisheries heavily relies on the population's ability to replace fish that have been caught.

Another impact of warming oceans is the change in fish distribution. To escape rising surface temperatures, fish are migrating to deeper waters. This shift necessitates adaptations in the fishing sector, including changes in fishing gear design and increased operational costs. Some marine models predict a significant loss of fish populations in Indonesian waters due to ocean warming. As a tropical country, even a small temperature increase in Indonesia can have substantial effects, especially as many fish species move towards cooler regions at higher latitudes. For instance, skipjack tuna populations are showing a tendency to shift northward, moving towards areas around Taiwan. This evolution poses a risk to Indonesia's fisheries, potentially leading to the loss of local species that are currently vital for the fishing industry.

“

They are heading towards areas around Taiwan.