Community-Based Stock Enhancement and Fisheries Management of the Japanese Flounder in Fukushima, Japan

Abstract

In Fukushima Prefecture, one million hatchery-reared juvenile Japanese flounder Paralichthys olivaceus have been released annually in the stock enhancement program since 1996. A community-based management system is used for this flounder fishery, where fishers pay 5% of their annual landings to operate the stock enhancement program. Also, since 1993, fishers have consented not to catch flounder <30 cm total length to maximize economic gains from the investment in stock enhancement. Our fish market surveys revealed that released flounder annually contributed an additional 30-90 tons to the catch. However, the economic efficiency of stocking has reduced since 1996, which has been largely attributed to a decline in fish price and recapture rate. Another problem is that the population dynamics of wild flounder have never been considered during implementation of the stock enhancement program. The occurrence of a dominant year-class of wild flounder causes a dramatic increase in landings and removes the need to release hatchery-reared juveniles. However, the program cannot be easily terminated because it plays important roles in having fishers recognize the importance of fishery management. It is a difficult but important realistic problem concerning how to make the stock enhancement program more flexible and effective.

Seasonal and spatial variations in prey utilization and condition of a piscivorous flatfish Paralichthys olivaceus

“…The Sendai Bay-Joban area is highly productive for Japanese flounder, possibly resulting in high stocking effectiveness (Fujita et al 1993, Tomiyama et al 2008a, with an annual commercial catch of this species of >1000 t in Miyagi, Fukushima, and Ibaraki Prefectures from 2006 to 2008 (Kurita et al 2010). The present study demonstrated the 2 predominant food items (anchovy and sandlance) for Japanese flounder in this area.…”

“…Because this fishery is managed to restrict the landing of small Japanese flounder (< 30 cm total length [TL]; Tomiyama et al 2008a), the 4640 individual wild and released Japanese flounder sampled at the fish markets were ≥30 cm TL. Location of capture of these samples was recorded by asking the fishermen who caught the landed samples or by inferring from the operation area of each fishery community.…”

Rapid fluctuation in infection levels of Neoheterobothrium hirame (Monogenea) in Japanese flounder Paralichthys olivaceus in the Joban area, Japan

“…Additionally, N. hirame infection causes behavioural changes in juvenile P. olivaceus which may enhance predation risk (Shirakashi et al ., 2008). The effects of N. hirame infection on the P. olivaceus stock, however, have been considered not to be serious because of the stable high commercial catch of P. olivaceus in this water, >400 t in 1998–2002 (Tomiyama et al ., 2008 b ) during high infection levels (Fig. 2) and because of the high stocking effectiveness (Fujita et al ., 1993; Tomiyama et al ., 2008 b ).…”

“…Host body L T was assigned to four classes of 150–299, 300–399, 400–499 and ≥500 mm, as above. The cumulative landed number of 1 and 2 year‐old wild and released P. olivaceus from September to December, in that year, estimated from the fish market surveys (Tomiyama et al ., 2008 b ) was used as the index of S HP . Parasite mean intensity ( n host −1 ) × S HP × parasite prevalence (%) ×10 −2 in winter of the previous year was used to estimate S PP .…”

Understanding and Managing Enhancement Fisheries Systems

“…Such transformations are facilitated where the number of decision makers is small, and their interests are well aligned with those of the key stakeholders and by supportive external arrangements (Ostrom, 1990). The transformed institutional arrangements can be far more effective at regulating resource use than those previously in place, and this may play a greater role in determining outcomes than the release of cultured fish per se Drummond, 2004;Tomiyama et al, 2008).…”