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Sarufutsu River “Jumping” with Itou Salmon, Researchers Report

In the field of conservation, we are often faced with the question “Is a certain species or population secure?”  As I mentioned in my earlier blog this year, it is not an easy question to answer, particularly for river fishes that are elusive by nature.  However, I am happy to report we are making substantial progress on answering that very question through our field studies of itou “ee-toe”, a mysterious member of the great salmon family found in east Asia.

I just recently returned back from a Fulbright fellowship in Japan and have had some time to summarize this year’s findings and reflect back on our project.  We had another successful field season, and I am eager to report the news.

Soon after submitting my blog to National Geographic “Water Currents” in late April, the itou arrived at our study site.  Like many populations of returning salmon, it started with a few early “pioneers”, but quickly grew to a dramatic peak.  Indeed, we broke our record for daily passage by our site, with 146 of these giants passing our site in a single day!  That was a day to remember (29 April) as the site was full of jumping itou, with occasional flashes of bright red as the males struggled past our site to get to the spawning grounds (Figure 1).

itou 1

Figure 1. Two male itou courting a larger female in the Sarufutsu spawning grounds in northern Japan. Photo Credit: Pete Rand.

We had our “magic” acoustic camera in the water for nearly 4 weeks.  I made the daily drive from my home away from home (Kasai Ryokan, a traditional Japanese inn in the small town of Onishibetsu) to my study site on the Sarufutsu River.  My mantra all the while was: “Must bring power (charged batteries) out, and data (GB) back”.

Once back at the ryokan, I spent most of the rest of the day pouring through the sonar records using special software so I could come up with a daily count (Figure 2).  By dinner time each day, there was growing interest among the “itou watchers” asking: “Pete-san, what’s the count?”.  This was driven not by just idle curiosity, but by a desire to see (and film) these elusive fish in the wild, a pastime for a growing number of Japanese!

 

figure-2

Figure 2. On the left, the author holds the “magic camera” (ARIS 3000, soundmetrics.com).  On the right, a still image of two itou produced by the camera, captured at our study site this spring.  Photo Credit: Koichi Osanai.

Obviously, there was quite a bit of excitement when I announced results from our sampling on 29 April.  This turned out be over 30% of the entire run!  We counted a total of 425 adult itou passing our site this year, greater than 20% more than last year’s count of 335 (Figure 3).  It is a simple story to tell with only two years of data, but drawing broader inferences from two years of data is a tenuous scientific exercise!  We counted substantially more fish this year, but a clearer trajectory of the population is only possible with continued monitoring.  Periodic assessments like this can provide a solid foundation on which to gauge whether our conservation work is being effective.

figure 3Figure 3. Itou arrived earlier, and in greater abundance, this year compared to last year.  Blue bars are data from 2013, and red bars are data from 2014.

 Serendipity, and the perils of migrating upriver

Sometimes timing just works out.  We planned an outing one afternoon to take a look at some river habitat for itou in the upper watershed.  I traveled with a few members of the local conservation group, Itou no kai.  Soon after pulling off a logging road, we took note of a problem “perched culvert” intended to pass water (along with fish, although clearly not by design!) underneath a road (Figure 4).  At that point in our trip, as we looked at the river pushing fast through that metal pipe, we could all envision the difficulty a large itou would have navigating through this obstacle.

fig4Figure 4.  Culverts like this are one of the most challenging obstacles for itou to pass along their way from the ocean to the spawning grounds in the headwaters of the Sarufutsu River. Photo Credit: Pete Rand.

We only had to wait a few minutes before we got an opportunity to move beyond our imagination and see the grim result of giant itou migrating past that culvert.  We observed a spawning pair in shallow water with nearly identically injuries on their heads – the only plausible explanation was the injuries were a result of colliding with the sharp edge of that culvert as they attempted to get upriver (Figure 5).

fig5

Figure 5.  This picture of an injured spawning pair of itou serves as a reminder to keep the migration path connected and safe so itou can make their way each year to the spawning grounds. Photo Credit: Maki Yamamoto.

Luckily this is an easy fix – new culvert designs allow for easier passage of water, in-stream wood and fish.  Our Japanese partners have notified the forest agency and requested that the culvert be replaced or removed to allow freer passage of itou.   I hope to report back on whether this particularly tributary stream has been restored back to a more natural state.

The Future for Itou

After fully analyzing our data and reporting our results, we are now facing questions about the future.  At the Wild Salmon Center we constantly explore ways of maintaining investment in time and resources for the long-term to assure this species persists.  Our work in the Sarufutsu has helped us maintain the international spotlight on this river and this fish, but it is going to take a serious commitment from us and our partners to continue conservation and monitoring work across the species’ range.  In the parlance of conservation, itou is a flagship species, so focus on this particular fish helps us protect a variety of taxa and the river ecosystem itself, and also helps us move toward enhanced economic benefits from ecotourism and salmon fisheries.  For this particular species, we have decided to work intensively in three rivers: the Sarufutsu in Japan and the Koppi and Nabil Rivers in neighboring Russia.  For taimen, this set of rivers offer the greatest hope for fulfilling our organization’s mission of protecting the last, best salmon river ecosystems of the Pacific Rim.

A definitive answer to the question of whether itou are secure in Sarufutsu River remains an open question, but our work over the past few years there provides some hope that future generations will be able to see these amazing fish migrating up this amazing river!

Comments

  1. Pete Rand
    Portland, Oregon
    August 5, 2:33 pm

    Thanks, Zeb! We will definitely call on you for help and support! Alot of credit goes out to our amazing Japanese partners. Our work will continue in Japan, and we continue our work in neighboring Russian Far East. It is good to follow our work at @wildsalmoncntr @pete_rand

  2. Zeb Hogan
    Reno, Nevada
    August 4, 9:48 pm

    Thank you for taking the time to share your work with us Pete. It’s heartening to hear that the numbers of itou increased this year. Let’s hope those problem culverts get fixed soon. Congratulations to you and your partners and best of luck with your future efforts. Please let me know if I can help in any way.