I have noticed a rapid and substantial increase in the catch of albacore in the Indian Ocean by Indonesia in recent years. I felt curious about this phenomenon because I had thought Chinese Taipei is the dominant country catching albacore in the Indian Ocean. My curiosity was confirmed at the Annual meeting of the Indian Ocean Tuna Commission (IOTC) held last May in Mauritius where serious arguments over the management of albacore stock were reported.
A significant reduction in tuna fishing activities in the Western part of the Indian Ocean has been attributed to piracy off Somalia, forcing longline fishing vessels to shift their fishing grounds to the southern Indian Ocean. Their target fish is sashimi grade albacore and thus the catch amount has increased rapidly. In the past, albacore in the Indian Ocean was exploited almost exclusively by longline fishing vessels, particularly by Chinese Taipei vessels. However, Indonesia remarkably increased its catch of albacore in recent years, even slightly exceeding that of Chinese Taipei for some years.
The Scientific Committee (SC) of the IOTC recognized that overfishing of the albacore stock is occurring and recommended to reduce the catch by 20%. However, Indonesia claimed that its catch is much less than the figures used in the stock assessment. The arguments forced the Commission to have the SC conduct a stock assessment again next year and the management measures will be considered based on the new assessment.
I personally felt doubt in the accuracy of the catch statistics. I found the trend of abundance indices used in the assessment differed among the major longline fishing countries, especially in recent years. In my view, since the size of fish taken by longline vessels is similar, the indices should show a similar trend for any longline vessel of any country. Both the catch statistics and the interpretation of different trends in recent abundance indices should therefore be carefully reviewed in order to assess the stock status more certainly.
If the albacore is really declining, its main cause may be due to the increase in the number of small longline vessels. In fact, the number of small longline vessels has rapidly increased and it now far exceeds the large longline vessels. This happened through improvement in the fishing efficiency and the economic competitiveness of small longline vessels. The increase of the number of small longline vessels seems not to be well acknowledged by the IOTC but it should start to seriously consider measures to control the fishing capacity of the small longline vessels in order to ensure the sustainability of the albacore fishery and the stock in the region.
In general, management of small longline vessels (less than 24 m in length) has been a rather low key issue hidden by the management of large longline vessels. However, in view of the fact that concern is also rising in the South Western Pacific over expansion in the capacity of small longline vessels, I think RFMOs and their parties should pay more attention to the impact to tuna resources caused by the unlimited expansion of small longline vessels.