Supplementary comments from newspaper interviews about Japanese eels

Supplementary comments on the interview in the Mainichi Shimbun (reported on October 29, 2025 "Are Japanese eel populations increasing? Two conflicting papers, third-party assessment") Japanese blog of 8 Nov. 2025

• Kaifu et al. (2025)'s criticisms of Tanaka (2014, 2025) are based on three main points:

1. The CPUE data for glass eels includes both under-reporting and over-reporting.
2. The data includes a mixture of information on eel fishing and bycatch, meaning that effort is not limited to eels.
3. The catch, including releases, cannot be said to reflect the resource abundance.　However, Tanaka (2025) conducted a sensitivity analysis that took into account unreported data (Figure 6b).

• On the other hand, Tanaka (2025, p. 8, left column, below Figure 7) criticized Kaifu & Yokouchi (2019) for failing to ensure representativeness of the resource status due to the lack of a sampling plan and the small scale of the survey.
• These criticisms are valid for both (and also for Kaifu et al. 2025). This is unavoidable, as the assessment is based on incomplete information.
• Regarding the criticism of Tanaka (2025), the question is whether the stock assessment would qualitatively change if these factors were corrected. If the unreported rate has remained constant both in the past and now, the absolute stock abundance would actually be higher (Tanaka Figure 6b). If the unreported rate was much higher in the past, it is unlikely that the stock has recovered (although it is questionable whether it continues to decline sharply). (2) If dependence on eel fishing has been lower in recent years, using total effort as the denominator of CPUE would actually underestimate the stock recovery rate. If dependence has been higher in recent years, the opposite would be true. (3) If the glass eel catch rate is lower now, an analysis including releases would not necessarily underestimate the true rate of decline. If it is higher now, the opposite would be true.
• I don't mind Kaifu et al. using unpublished data, but to maintain anonymity, the catch amount data are not shown. Unfortunately, we are unable to confirm their regression model (though Kaifu can replicate Tanaka 2025 to some extent). It's likely that the reviewers also pointed this out. Furthermore, Kaifu et al. (2025, Table 3) treat each fishing ground as an independent population and provide point estimates of the decline rate for each fishing ground. However, the Japanese eel stock is actually a single entity, and parent and offspring likely do not migrate upstream to the same location. A single overall decline rate should be estimated as an interval estimate. Including Chiba, where the population increased 4.5-fold (this could be adjusted, for example, by limiting the overall population to the October-December period), would result in a value with a reasonable range. To begin with, CPUE is not suitable for quantitatively assessing the true decline rate of stock abundance (R. Myers's infamous 90% decline in tuna species was later criticized, and it's now said to be at most 30-50%). However, Kaifu's analysis is also valuable. The fact that it can only be published anonymously is "abnormal." He persisted in his analysis. 
• The results for glass eels are consistent in both cases, suggesting a flat population (or no significant increase or decrease, as stated in the abstract of Kaifu et al. 2025). However, Kaifu et al. 2025 includes the results for glass eels, excluding as many unreported cases as possible, in Figure 4 and Table 4. Table 4 does not specify the estimates and SEs, but the likely growth rates are -0.021 and +0.101 (per year?). Simply applying SE (whether this is appropriate or not is unclear, but the paper lacks the data necessary for further analysis) would suggest a 0.17 increase and a 0.09 decrease (unclear increase or decrease). This is probably the most reliable conclusion. If this is the case, we cannot deny the possibility of continued decline (a decrease of more than 80% over 24 years [or, at the same rate, a decrease of more than 60% over 14 years] is likely less than 5%), but there is also a possibility of recovery. 
• This alone may not be sufficient evidence for listing species under CITES. There is no doubt that the decline has been significant compared to half a century ago. However, it is unclear whether the decline has continued since 2010. If the proposal had been made at the same time as the European eel, there would have been little opposition to listing it on CITES Appendix II, but it would be better to wait a little longer to see the results of subsequent conservation efforts. It's unclear why it's being proposed now.
• The international treaty could be throwing cold water on the issue without waiting for the results of Asian countries' efforts since around 2015, but perhaps that's their raison d'être. Like the IWC, CITES is a "fossilized" treaty based on a dichotomy.
• The Red List is determined based on past decline rates, so it likely met the numerical standards of the IUCN (criteria A) and the Japan Ministry of the Environment at the time (criteria E). The Red List is not based on extinction risk itself, so even with a CR rating, fishing is still possible, as with bluefin tuna, and some species are recovering through exploitation. I have been criticizing the Red List criteria for about 30 years (Matsuda et al. 1997), saying they are strange, but the IUCN criteria (ver. 3.1) has been clearly stated that "species that meet the numerical criteria will be included even if they are known to have a low risk of extinction".

Resolutions from the World Heritage Committee regarding Steller Sea Lions in Shiretoko

In 2024, we revised the Basic Management Policy for the Steller Sea Lion (see below), which included the Shiretoko World Heritage Site within the management area. We gained a general understanding of this from the World Heritage Committee (see 47 COM 7B.7). We are very grateful for this. It was important for us to gain an understanding of the concerns of both the local fishers, who suffer damage to their industry due to sea lions, and the World Heritage Committee, who are concerned with the Outstanding Universal Values of Shiretoko. We will continue to strengthen the scientific evidence in order to promote the coexistence of fisheries and sea lions, while striving for both conservation and human activities.

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How to Build Matrix Population Models from Process Components

 Literature Introduction of "Notes on Building Matrix Population Models: Insights From Combining Distinct Matrices for Survival, Reproduction, and Growth" (Matsuda H & Taper ML 2025, Population Ecology POPE70005, doi.org/10.1002/1438-390x.70005) (full manuscript) (See html for lecture pdf & video).

Abstract

We propose a unified method for formulating matrix population models in wildlife and fisheries management, adaptable to variations in population measurement timing and natural and human-induced mortality. For populations with a common and short breeding season, this approach applies to age-, size-, and stage-structured populations. The process is considered separately as three: survival, reproduction, and age increment or growth, with the respective matrices designated as S, B, and G. In the age-structured model, reproduction and age increment occurs simultaneously, and are expressed as a matrix model of S(BG) if the population census is taken immediately before the parturition, and (BG)S if it is taken immediately after the parturition. In the size- or stage-structured model, growth and survival proceed in parallel, and are expressed as a matrix model of (GS)B if the population census is taken just before the parturition, and B(GS) if it is taken just after the parturition. When the population census is taken at any other time, the survival rate from the parturition to the census and the survival rate from the census to the parturition can be considered separately. Furthermore, even when capture mortality is given as the number of individuals rather than a rate, a unified formulation by capture time is possible by expressing the number of captures as a vector. 

Inaugural Address by the New Chair of Earthwatch Institute Japan

In recent years, the fusion of traditional knowledge and scientific knowledge has progressed beyond the conventional scientific framework. The role of citizens in advancing science has also become increasingly important. Since its founding in 1971, Earthwatch has been a leader in citizen science, sending citizen volunteers into the field to advance research activities with corporate support. In the future, environmental issues will become increasingly important and urgent, and we are entering an era that will require a new "relationship between people and nature”. We would like to work hard to further develop citizen science by respecting diverse values and positions and providing a forum for free and lively exchange of opinions. We sincerely appreciate your participation and cooperation.

(Original Message in Japanese)

On the issue of mobile base stations at Cape Shiretoko

 2024-06-25

I would like to make four brief comments on mobile base stations.

The current discussion seems to be about whether the Scientific Committee will acknowledge the impact on OUV*1, but as with dams and sea lions, it is more important how the World Heritage Committee will recommend. If there is a possibility of criticism, it is important to develop measures to deal with it. I apologize for being late in noticing the seriousness of this issue.

According to a recent investment policy on ESG, environmental, social and corporate governance [i], industries that have a negative impact on World Heritage sites are "subject to a cross-sectoral ban on investment, financing, etc." Although there is a note that "it is different if there is prior consent from the government of the country," if such a problematic project is forced through, it could have a major impact on the management of mobile phone companies and construction contractors. *2

The mayor of Rausu has made his opinion public. Citing the tourist boat accident, he explained that the mobile base station is a project to protect the lives of users. It also says that the World Heritage site "had a promise that it would not cause any disadvantage to fishermen." If we are to protect the lives of users, we would like to see the report of the third-party accident investigation committee made public*3. Frankly, I think that the cause of the accident was the lack of safety compliance obligations, and that citing this to build mobile base stations is a red herring. If the World Heritage Committee also questions the cause of the accident, it may become a problem beyond the impact on OUV. In the UN Principles for Responsible Investment and ESG investment, management governance is as important as environmental issues.*2

Finally, before the establishment of the Marine Area Working Group in February 2005 when the site was registered as a World Heritage Site, the members of the Working Group and the Fisheries Association had direct discussions. After that, the fishermen expanded the voluntary no-fishing zone for Alaska pollock, which was one of the deciding factors in meeting the condition of raising the level of protection of the marine area. In other words, the Fisheries Association contributed greatly to the registration of Shiretoko as a World Heritage Site, and it should have been evaluated that Shiretoko's fishing activities and the World Heritage Site have the same aspirations. I think it is up to the Marine Area Working Group to decide whether the suspension of the base station construction violates the promise made at the time not to impose new restrictions on fishing activities under the Natural Parks Act and other laws without the consent of the Fisheries Association in order to manage the Shiretoko World Heritage Site, but the expression "will not cause any disadvantage" is not literal. However, I think that the Scientific Committee should have a dialogue with those who want to build the base station on this issue as well.

*1 Outstanding Universal Value = An outstanding cultural and/or natural value that transcends national boundaries and is of common importance to present and future generations of humanity as a whole. There are 10 OUV criteria for World Heritage inscription.

*2 Added 7/11: KDDI has published the TNFD report. It does not say that they will consult with experts as a contribution to biodiversity conservation (p. 7). Instead, it says, "The latest name recognition AI will identify the types of plants and animals, so a person, even if she/he is not a taxonomist,  can conduct a highly accurate survey just by taking a photo" (p. 23).  

*3 Added 6/28. Found on the website. I will discuss this in more detail in a separate section, but Chapter 5, "Measures to prevent recurrence," states that "mobile phones will be excluded from statutory wireless equipment." However, in 5.3.5, "Improvement of the communications environment in the waters around the Shiretoko Peninsula," it states that "mobile phone carriers and relevant ministries and agencies, etc." have "launched the Shiretoko Peninsula Regional Communications Infrastructure Strengthening Project, which will advance concrete efforts to improve the mobile phone communications environment in the Shiretoko Peninsula region." *Report on marine accident investigation into mobile phones as statutory wireless equipment, September 4, 2023, 

concern about the recent earthquake and aircraft accident in Japan

 

Dear colleagues,

I sincerely appreciate your thoughtful message expressing concern about the recent earthquake and aircraft accident in Japan.

Noto holds a special place in my heart as it is a base of the Kanazawa University Ecology Group. They started another UNESCO Chair since 2023.  I have been there several times.  One is a UN University event at Nanao city. Noto.

There was a significant incident at Haneda on the 2nd. Personally, I frequently take flights from New Chitose (Sapporo) to Haneda every year. The fact that there were no casualties among the passengers is, at the very least, a relief. My secretary is a former flight attendant, and her husband works for JAL. She was deeply shocked when she saw the news but she mentioned that the annual evacuation drill must have been a success. I told her that JAL should take pride in that.

I have had the opportunity to witness the beauty of the Shiretoko World Heritage Site from a Japan Coast Guard plane. Unfortunately, this incident occurred while the team was departing for Noto for relief efforts.

As we embark on a new year, my fervent hope is that it will not be marred by misfortunes and disasters in the world.

 Best,

5/13松田裕之最終講義 ご意見ご質問ありましたらお願いします

 

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