Impact of the Great East Japan Earthquake on the oyster market: a difference-in-differences estimation

This paper uses prefecture-level data during 1970–2015 to examine the impact of the Great East Japan Earthquake on the oyster market in Japan. Using a difference-in-differences estimation, we find that the disaster decreased the oyster production by 65%. This negative effect peaked in 2012, but did not completely disappear 4 years after the disaster. In contrast, we find that oyster prices only increased by 26%, and the parameter estimate is only marginally significant. Moreover, this impact is relatively constant over time. The apparent lack of price changes corresponding to large production changes can be caused by three factors: elastic demand, market integration, and demand shocks. We examine each possibility and conclude that the demand shocks due to the concern for radioactive contamination is the most likely cause of the small impact on oyster prices.     

Macropore structure and water management affect greenhouse gas emissions in agricultural fields

Paddy and Water Environment - The process of greenhouse gas (GHG) emission processes is substantially affected by soil factors. Here, an intensive experiment was conducted to observe the effects of...     

Econometric analysis of the factors contributing to the fish price increase in coastal TURFs in Japan: the case of income-pooling fishery for coastal shrimp “Sakuraebi Sergia lucens”

While rights-based management systems have often been encouraged as effective management tools, few studies have analyzed the effects of those systems empirically. In this article, we have focused on a special form of the territorial use rights in fisheries strategy, namely, an income-pooling system, and examined the effects of this system empirically. Earlier studies have regarded the control of fish landing amount and improvement of the quality of fish as the two main determining factors in such a system. Consequently, in our study, we estimated the relationships between these two factors and the price of fish using the econometric method. The results show that the two factors do indeed have significant effects on price changes.     

Annual variation in otolith increment widths of walleye pollock (Gadus chalcogrammus) larvae in Funka Bay,Hokkaido, Japan

To clarify relationships between year‐class strength and larval growth of walleye pollock (Gadus chalcogrammus), and oceanographic conditions in the Pacific stock off Hokkaido and Tohoku, Japan, we undertook conductivity/temperature/depth (CTD) observations and investigated larval densities, larval otolith increment widths and larval prey densities (of copepod nauplii) of the 2008, 2009, 2010 and 2011 yr classes in Funka Bay. Oyashio Coastal Water (OCW) flowed into the bay in late February in 2008, 2010 and 2011, and the mean water temperatures decreased to 1.9–3.1 °C in March. OCW was not observed in 2009, and it was warm in late February (≥3.4 °C). Increment widths of lapillar otoliths during the yolk‐sac stage were wide in 2009 and 2011, medium in 2010 and narrow in 2008. Increment widths during the first‐feeding stage tended to become wider as the hatch month progressed, and the annual variation during the first‐feeding stage was larger than that of the yolk‐sac stage. The densities of the primary food for the larvae were high in 2008 when larval increment widths were narrowest, so the effect of prey abundance on larval growth appeared to be small. The ranking of the larval abundance in March was nearly coincident with that of the increment width during the larval stage. We, therefore, suggest that the larval growth rate is associated with the mortality rate and that the growth–mortality hypothesis may be applicable to walleye pollock in Funka Bay. Feeding success under warm water conditions may be an important factor that contributes towards high growth rates.     

Change of fish fauna in ponds after eradication of invasive piscivorous largemouth bass,Micropterus salmoides,in north‐eastern Japan

• 1. The change in fish fauna was monitored in ponds within irrigation systems in Iwate prefecture, north‐eastern Japan to evaluate the effectiveness of eradicating the invasive piscivorous largemouth bass, Micropterus salmoides.
• 2. Eleven study ponds were categorized into three pond groups: bass‐dwelling (n=3), bass‐eradicated (n=3) and non‐invaded ponds (n=5).
• 3. Species richness and diversity, which temporally decreased in bass‐dwelling ponds, increased in bass‐eradicated ponds. Furthermore, in bass‐eradicated ponds, the mean numbers of topmouth minnow and freshwater goby were gradually restored, but in bass‐dwelling ponds the numbers decreased and both species eventually disappeared.
• 4. Although the eradication of piscivorous invaders is helpful for restoring fish species diversity in ponds, its effectiveness varies among species, and other alien fish such as the rose bitterling (Rhodeus ocellatus ocellatus) often invade and proliferate in the bass‐eradicated ponds.
• 5. To ensure successful restoration of native biota and avoid undesirable results, it is necessary to plan and implement continuous monitoring and adaptive management after eradication of alien predators. Copyright © 2010 John Wiley & Sons, Ltd.

     

Manageable risks and the demand for food products: the case of oyster

The risk of norovirus food poisoning from oyster consumption can be minimized by consumers, as thorough cooking can destroy norovirus. This paper uses data from 23 prefectures in Japan during 1970–2010 to examine how the demand for oysters responds to this manageable risk. We find that the incidence rate of norovirus has no effect on the price of oysters in prefectures that specialize in oysters for cooking, whereas it has significant negative impacts in prefectures that produce oysters to be eaten raw. These results indicate that consumers respond differently to manageable and non-manageable risks.     

Niche processes and conservation implications of fish community assembly in a rice irrigation system

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Structural changes and imperfect competition in the supply chain of Japanese fisheries product markets

This study analyzed the existence of imperfect competition, and the time period for which it existed in the supply chain of fisheries products in Japan from 1976 to 2009. An empirical analysis of the imperfect competition using a structural model robust to nonstationary time series revealed that sellers of horse mackerel, Japanese flying squid, and sardines in wholesale markets located in consumption areas had market power before 1993 in upstream markets. In downstream markets, retailers of horse mackerel and sardines had market power not only before 1993 but also after 1992, and retailers of Pacific saury and red seabream had market power before 1993. However, there were a number of periods when the detected imperfect competition was mostly less than that in upstream markets. The findings of this study are consistent with those of a previous study, which pointed out that sellers in wholesale markets lost negotiation power due to the emergence of large retailers, such as supermarkets, who buy directly from producers, trading companies, wholesalers at production sites, etc., especially after 1992. A comparison with another previous study indicates that market power and asymmetric price transmission are closely related.     

Species,space and time: A quarter century of fishers' diversification strategies on the US West Coast

Diversification within fisheries operations can serve as an important form of self-insurance against natural, regulatory and market risks to fishers' livelihoods. Diversification can take many forms, and yet the literature has primarily emphasised diversification across species to the exclusion of spatial and temporal dimensions of diversification. We analyse trends in diversification across species, space and time for all fishers along the entire continental West Coast of the United States from 1990 to 2015. Our findings reveal the importance of untangling both compositional (i.e. driven by changes in fleet composition) and individual (i.e. driven by within-owner changes in diversification strategies) dimensions of diversification by showing how these effects have moved in contrary directions for all three forms of diversification. We also demonstrate how increases in temporal diversification have overwhelmed the overall stability of species and spatial diversification to leave the current fleet less exposed to financial variability compared to in the early 1990s.