Feats and Defeats in Flatfish Stocking: Determinants for Effective Stocking

Støttrup, Josianne

doi:10.1002/9780470751329.ch6

Cited by 3 publications

(3 citation statements)

References 35 publications

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“…releasing hatchery-reared [HR] juveniles) of commercially important organisms. Stocking should be implemented within the 'available' carrying capacity (Støttrup 2004), to allow for a residual production of prey after consumption by both existing and stocked predators. Some studies suggest me thods to determine stocking density within the carrying capacity (Taylor et al 2005, Yamashita et al 2006, Taylor & Suthers 2008, Ochwada-Doyle et al 2012), but current stock enhancement programs have not given this concept much consideration.…”

Section: Introductionmentioning

confidence: 99%

Feeding relationships among fishes in shallow sandy areas in relation to stocking of Japanese flounder

Tomiyama¹,

Uehara²,

Kurita³

2013

Mar. Ecol. Prog. Ser.

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Juvenile Japanese flounder Paralichthys olivaceus inhabit shallow sandy areas and consume chiefly mysids. Hatchery-reared P. olivaceus (ca. 100 mm in total length) released in stock enhancement programs also consume mysids. To examine whether stocking is implemented within the available carrying capacity, we assessed the feeding relationships among fishes, based on the stomach contents of fishes collected off the coast of Fukushima, Japan. Similarity in diet suggested that 10 species, particularly the poacher Occella iburia and nibe croaker Nibea mitsukurii were potential competitors of P. olivaceus juveniles for food. Large inter-annual variability in the abundance of these competitors was observed, suggesting variability in their consumption of mysids. The predominant mysid Orientomysis mitsukurii was abundant every year, and growth rates of wild P. olivaceus, estimated from otolith microstructure, were mostly high (>1 mm d −1 ), even in the year when wild P. olivaceus were highly abundant. In our statistical model, abundance of mysids and consumption of mysids by fishes significantly affected the growth rates of wild P. olivaceus but only accounted for a small proportion (i.e. explained 2.2 and 2.4% of variance, respectively) of the total compared to the body size of juveniles (30.0%) and bottom water temperature (4.5%). These results suggest that the productivity of mysids is usually high enough to support the production of mysid consumers, but exceptionally high abundances of wild P. oliva ceus or other competitors can reduce the available carrying capacity. In such a situation, stocking should be restricted so as not to reduce productivity of wild fishes.

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Section: Introductionmentioning

confidence: 99%

Feeding relationships among fishes in shallow sandy areas in relation to stocking of Japanese flounder

Tomiyama¹,

Uehara²,

Kurita³

2013

Mar. Ecol. Prog. Ser.

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“…Trials with turbot, Psetta maxima (L.), in an exposed coast in inner Danish waters showed that it is possible to stock flatfish species to increase local recruitment, if both the ecological and biological criteria for stocking are addressed (Støttrup, Sparrevohn, Modin & Lehmann 2002; Støttrup 2004). One of these criteria involves choice of location and ensuring an ideal habitat with regards to both biotic and abiotic factors for the released fish.…”

Section: Introductionmentioning

confidence: 99%

The quality of release habitat for reared juvenile flounder, Platichthys flesus, with respect to salinity and depth

Andersen¹,

Schou²,

Sparrevohn³

et al. 2005

Fisheries Management Eco

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One prerequisite for a successful stocking programme is the choice of an appropriate release site, which would ensure good growth, survival and recruitment to the local fishery. The influence of different salinity regimes on habitat quality for juvenile flounder, Platichthys flesus (L.), was examined in Danish inshore waters using enclosures to study growth and survival. Three locations were chosen: Virksund (V) -constant low salinity at 10&; Harre Vig (HV) -constant high salinity at 24&; and Hjerk Nor -variable salinity, 0-25&. Fish movement was examined, using a diffusion model, at the first two sites. At HV the fish had unrestricted dispersal opportunity resulting in average individual movement of 45 m day )1 . Fish at V were restricted in dispersal in one direction because of a dam, about which they would concentrate under certain hydrographical conditions. Growth was highest at the locations with stable salinity and mortality highest at the location with variable salinity.

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“…However, growth of other strong year-classes such as the 1999 and 2004 year-classes ( Figure 4) was not decreased, possibly because food was generally abundant and carrying capacity was seldom reached (van der Veer et al, 2000). Available carrying capacity is a necessary condition for successful stocking (Støttrup, 2004). Excessive releases (overstocking) will inhibit growth of wild flounder (Yamashita et al, 2006) and thus result in the reduction of wild fish production, a form of lost production caused by releases.…”

Section: Issues Concerning Stocking and Wild Population Dynamicsmentioning

confidence: 99%

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

Tomiyama¹,

Watanabe²,

Fujita³

2008

Reviews in Fisheries Science

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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.

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Feats and Defeats in Flatfish Stocking: Determinants for Effective Stocking

Cited by 3 publications

References 35 publications

Feeding relationships among fishes in shallow sandy areas in relation to stocking of Japanese flounder

Feeding relationships among fishes in shallow sandy areas in relation to stocking of Japanese flounder

The quality of release habitat for reared juvenile flounder, Platichthys flesus, with respect to salinity and depth

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

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