How the world’s most widely used insecticide led to a fishery collapse

Neonicotinoids disrupt aquatic food webs and decrease fishery yields

1. Masumi Yamamuro1,2,*, 
2. Takashi Komuro2, 
3. Hiroshi Kamiya3, 
4. Toshikuni Kato3, 
5. Hitomi Hasegawa4, 
6. Yutaka Kameda5

 See all authors and affiliations

Science  01 Nov 2019:
Vol. 366, Issue 6465, pp. 620-623
DOI: 10.1126/science.aax3442

(https://science.sciencemag.org/content/366/6465/620?fbclid=IwAR3EAGT-rGqgBSzpHTa4qIRSdntqeaGAkqTrfM7K2W3hjeyS7G5DVK5h-pI)

Abstract

Invertebrate declines are widespread in terrestrial ecosystems, and pesticide use is often cited as a causal factor. Here, we report that aquatic systems are threatened by the high toxicity and persistence of neonicotinoid insecticides. These effects cascade to higher trophic levels by altering food web structure and dynamics, affecting higher-level consumers. Using data on zooplankton, water quality, and annual fishery yields of eel and smelt, we show that neonicotinoid application to watersheds since 1993 coincided with an 83% decrease in average zooplankton biomass in spring, causing the smelt harvest to collapse from 240 to 22 tons in Lake Shinji, Shimane Prefecture, Japan. This disruption likely also occurs elsewhere, as neonicotinoids are currently the most widely used class of insecticides globally.

How the world’s most widely used insecticide led to a fishery collapse

Neonicotinoids wiped out plankton and fish in a Japanese lake, and are likely harming aquatic ecosystems worldwide, new research suggests.

In 1993, farmers in Shimane Prefecture, Japan began using

neonicotinoids in their rice paddies and agricultural fields.

Kilograms of neonicotinoids sold annually in Shimane Prefecture

May 1993

Start of neonicotinoid use

in Shimane Prefecture

Runoff containing neonicotinoids from fields and paddies was

linked to a dropoff of zooplankton biomass in Lake Shinji.

Monthly measurement of zooplankton in micrograms carbon per liter

present in water from Lake Shinji

May 1993

Start of neonicotinoid use

in Shimane Prefecture

Populations of commercial smelt and eel in Lake Shinji, which

were reliant on zooplankton and benthos as a source of food,

began to collapse.

Tons of smelt and eel, caught annually in Lake Shinji

SMELT

EEL

May 1993

Start of neonicotinoid use

in Shimane Prefecture

SMELT

EEL

JOHN KAPPLER, NG STAFF.

SOURCE: MASUMI YAMAMURO ET AL., SCIENCE, 2019

Ultrasensitive determination of 17β-estradiol in eel serum

Doping of transition metal dichalcogenides in molecularly imprinted conductive polymers for the ultrasensitive determination of 17β-estradiol in eel serum

Biosensors and Bioelectronics

journal homepage: http://ees.elsevier.com

A B S T R A C T

Molecularly imprinted polymers (MIPs) have been developed to replace antibodies for the recognition of target molecules (such as antigens), and have been integrated into electrochemical sensing approaches by polymerization onto an electrode. Electrochemical sensing is inexpensive and flexible, and has demonstrated utility in point-of-care devices. In this work, several 2D (conductive) materials were employed to improve the performance of MIP sensors. Screen-printed electrodes were coated by the electropolymerization of aniline and metanilic acid, commingled with target molecules and various 2D materials. Tungsten disulfide (WS2) with an average particle size of 2 μm was found to increase the sensitivity of detection of molecularly imprinted conductive polymer-coated electrodes to 17β-estradiol. As estradiol concentrations are important to eel aquaculture, we screened eel serum samples to determine their 17β-estradiol concentrations, which were found to be in the range 28.2 ± 3.6 to 73.0 ± 11.6 pg/mL after dilution. These results were in agreement with measurements using com-

mercial immunoanalysis.

鰻魚蓋飯常見的「蒲焼」，到底是什麼意思？

吃過鰻魚飯的話，一定見過「蒲焼」二字。「蒲焼」唸作「かばやきkabayaki」，意思是將鰻魚或海鰻切開後，取掉骨頭，串成一串後蘸上醬油、味醂等醬料後燒烤的料理。

圖片來源：PhotoAC

---

那為什麼這種料理要叫做「蒲焼」呢？據說是因為將鰻魚串起來的樣子長得很像「蒲穗」這種植物，所以才叫做「蒲焼」。理由意外地非常簡單。下次吃「蒲焼」這道料理時，就可以告訴朋友這個小知識啦！

(https://www.letsgojp.com/archives/413609/?fbclid=IwAR3eGWNksAtABW6B_kmtSc2eNffs96adWmJQOi6CWuKzfDsLkoxLdE63xOg)

https://www.wur.nl/en/news-wur/Show/First-observation-ever-of-a-spontaneously-matured-female-European-eel.htm?fbclid=IwAR2zHaIyxlSbJGegdtsoLOCFZtIUzB8wL8VX-Qa4vHNK-W-JwVwSgUYL-4g

First observation ever of a spontaneously matured female European eel

Published on

November 1, 2019

For the first time in history, scientists have observed a spontaneously matured female European eel. She was caught in 2002 and has since lived in the Finnish aquarium house Maretarium in Kotka. Researchers of Wageningen University & Research have, together with colleagues of the Natural Resources Institute Finland and the Maretarium, studied the eel to gain knowledge on the natural process of sexual maturation. The gained insights will contribute to the closing of the production cycle of eels in aquaculture. The information is also very important for conservation of the natural population.

Spawning in the Sargasso Sea

At the end of their life, European eels migrate from the European freshwaters to the Sargasso Sea to reproduce. When they leave the continent, they are 5 to 50 years old but still pre-pubers. After a 5 to 6,000 km swim trip, they reproduce and die afterwards. Two day old larvae have been caught in the Sargasso, to date still the most convincing evidence that reproduction should be occurring there. Naturally matured eels have never been caught, in the Sargasso Sea or elsewhere. In captivity only by long-term hormonal treatment eels can be matured artificially.

The live eels at the Maretarium (photo by Pauline Jehannet)

The spontaneously matured eel was a 43 year old female, stocked as a French glass eel in the Finnish Lake Vesijärvi in 1978. She was part of a batch of twelve eels that was re-caught again in 2002 and which was then transferred to the Finnish Maretarium in Kotka. Last summer this eel increased her belly size as a sign of the oocyte hydration response that occurs during the final stage of sexual maturation. Finally she died at a length of 114 cm and a weight of 3.3 kg with most oocytes having overripened but without having released any. The remaining eels will be closely monitored for progressing maturation.

Eel aquaculture and conservation of the natural population

Eels can be reproduced artificially by hormonal injections in captivity but the larvae die before they feed. “In Wageningen we can produce larvae weekly” says researcher Arjan Palstra of the Eel Reproduction Innovation Centre, a collaborative R&D initiative between Wageningen Livestock Research and the sustainable eel foundation DUPAN. “But what always has been lacking was a natural reference for the process of sexual maturation in eels. And that is important as the quality of the eggs and larvae that we produce could be improved.”

With the newly gained insights, the researchers expect to be able to improve the protocols and develop ways to naturally mature eels. And that will contribute to closing the production cycle as eels still cannot be propagated. But the information is also very important for management of the natural population and conservation of this iconic fish.

Kindai University has succeeded in incubating and growing for 50 days Japanese eels

Japanese university artificially incubates endangered eel species

 KYODO NEWS - Nov 2, 2019 - 14:22 | All, Japan

A Japanese university known for its technique to cultivate bluefin tuna has succeeded in incubating and growing for 50 days Japanese eels, an endangered species that is a sought-after delicacy in the country.

Kindai University, which sells the bluefin tuna it farms, said Friday it will also aim to achieve "full-cycle" aquaculture of eels, meaning incubating and cultivating eels and then obtaining second-generation eels from them, for commercial use.

[Courtesy of Kindai University]

In 2002, Kindai University became the first institution in the world to achieve full-cycle aquaculture of bluefin tuna. The fish has gained popularity as "Kindai tuna."

"With eels as well, we will try to achieve sustainable aquaculture, without depleting natural resources," said Shukei Masuma, head of the Aquaculture Research Institute of the university based in Higashiosaka, Osaka Prefecture.

Efforts to cultivate Japanese eels, designated in 2014 as endangered by the International Union for Conservation of Nature, have been led by the state-run Japan Fisheries Research and Education Agency, which succeeded with full-cycle farming in 2010 for the first time in the world.

Kindai University said about 30 eel larva, which were artificially incubated on Sept. 12 at its research facility in Wakayama Prefecture, have grown to about 2 centimeters over 50 days.

The university is separately growing around 1,100 larva. If things go smoothly, some of these are expected to grow to a marketable size next spring.

In a bid to cut back on aquaculture costs and workloads, Kindai will try to develop a feed that is less likely to pollute water, according to the university.

Nov 2, 2019 | KYODO NEWS