Scientists: Fish growth declining due to overfishing

Sydney (ANTARA) - Scientists from Australia warn that overfishing and environmental changes are eroding the biological foundations of many fisheries and reducing fish growth globally over the past century. To reach this conclusion, a team of researchers from James Cook University (JCU) in Australia analysed nearly 7,700 growth records covering 1,479 marine species from 1908 to 2021, and found a decline in growth performance since around 1908, with the largest declines concentrated in commercially valuable species. The research team measured growth performance, a biological characteristic describing the balance between growth rate and body size, over a 113-year period. The lead researcher, Helen Yan, said that various pressures triggered by human activities are causing large-scale changes to fish ecology and life cycles. “Managed fisheries have experienced an average decline in growth performance of 9 percent over the past century. This indicates that fish are growing to relatively smaller sizes and/or at slower rates,” said Yan, who conducted the research as part of her doctoral studies at JCU. She added that size-based commercial fishing practices, rather than temperature, are the main driver of the global fish growth decline pattern, although climate change may exacerbate its impacts. Intensive fishing leaves a clear biological footprint on fish populations, Yan continued, stating that the trend is most evident in temperate regions where fishing pressure is recorded as the highest. The team of scientists warns that smaller fish sizes and slower growth could alter food webs, reduce catch yields, and complicate recovery efforts, while emphasising the need for stricter catch limits, size and habitat protections, and longer-term monitoring to detect biological changes.