Assessing the Effectiveness of Releasing Cod Larvae for Stock Improvement With Monitoring Data

Chan, Kung‐Sik; Stenseth, Nils Christian; Kittilsen, Marte O.; Gjøsæter, Jakob; Lekve, Kyrre; Smith, Tim; Tveite, Stein; Danielssen, Didrik S.

doi:10.1890/1051-0761(2003)013[0003:ateorc]2.0.co;2

Cited by 23 publications

(34 citation statements)

References 23 publications

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“…For earlier studies that have used these data for ecological modelling, see Fromentin et al (1997Fromentin et al ( , 1998Fromentin et al ( , 2000Fromentin et al ( , 2001, Stenseth et al (1999), Bjørnstad et al (1999a,b) and Chan et al (2003a,b). Building upon the ecological model of Chan et al (2003b), we here extend the application of these monitoring data to testing the population genetic hypothesis suggested by Knutsen et al (2004).…”

Section: Methodsmentioning

confidence: 99%

Ecological and genetic impact of Atlantic cod larval drift in the Skagerrak

et al. 2006

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We evaluate the hypothesis that Atlantic cod larvae are passively transported by sea currents from off-shore spawning areas to settle in coastal waters, a hypothesis which has recently gained support from genetic analysis of cod in the North Sea-Skagerrak area. Such larval transport has been suggested to be an important mechanism behind the commonly observed low spatial genetic differentiation in many marine organisms. Here, we apply an ARMAX(2,2) model for juvenile abundance and use long-term monitoring data from the Skagerrak coast, constituting 54 continuous annual series from 1945 to 1997. Analysing the model, we find that the product of the size of the North Sea breeding stock and the strength of the net inflow of North Sea waters had a significant, positive effect on the abundance of coastal juvenile cod. The peak effect occurs during the month of March, just after spawning, when eggs and larvae remain pelagic and sensitive to currents. In contrast, we find no evidence of any direct effect of the North Sea spawning stock alone. Our analyses indicate that 15-20 000 0-group larvae from the North Sea reach each fjord per year, on average. This corresponds to about 1-10% of the total 0-group population in each fjord on average. These findings clearly demonstrate a direct link between larval drift and gene flow in the marine environment.

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Section: Methodsmentioning

confidence: 99%

Ecological and genetic impact of Atlantic cod larval drift in the Skagerrak

et al. 2006

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“…While some projects have made an effort to disperse released fish (Støttrup et al, 2002), random distribution would best be replaced by targeted releases at a suitable density. Targeted stocking may even prompt a return to restocking the oceans (e.g., Chan et al, 2003), by releasing eggs into key oceanographic areas such as remotely sensed fronts or eddies.…”

Section: Targeted Stocking Approachmentioning

confidence: 99%

A Predatory Impact Model and Targeted Stock Enhancement Approach for Optimal Release of Mulloway (Argyrosomus japonicus)

Taylor

Suthers

2008

Reviews in Fisheries Science

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Habitat, diet, and life history information were used to estimate appropriate stocking density and the potential predatory impact of a stocked finfish. Our Predatory Impact Model uses data from the literature for fish in freshwater or estuarine habitats. Model simulations were run for the Georges River Recreational Fishing Haven (RFH), Sydney, to evaluate appropriate stocking density and associated predatory impact. The estuary contained about 1,760,000 m 2 of key nursery habitat for mulloway (Argyrosomus japonicus), and 10% of mysid shrimp production within this habitat was assigned to support stocked fish, as mysids represent the immediate forage requirements of stocked mulloway. Given these values, this section of river could support 17,500 stocked mulloway of 8 cm TL. During the first 3.5 years post stocking, when mulloway are predominantly estuarine residents, predatory impact includes 1 t mysid shrimp, 80 t forage fish, 45 t prawns, 3 t miscellaneous invertebrates and 5 t cephalopods. For comparison, this predatory impact represents 107%, 154%, and 24% of the commercial fishery in Botany Bay/Georges River for forage fish, prawns, and cephalopods, respectively, for 3.5 years before the declaration of the RFH. To maximize the benefit of the approach, a targeted approach to stocking should be taken. Stocked fish should be stocked directly into key habitats, as opposed to being released from a few shore-based sites within the estuarine system.

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“…Parallel with this, a similar programme was launched in the northeastern USA (Earll, 1880;Solemdal et al, 1984). Recent statistical analyses have shown that these programmes did not result in any long-term increase in mature cod biomass in any of the relevant fjords/local areas (Chan et al, 2003). Coincidentally, from May to October 1983, the so-called breakthrough in cod rearing happened: 75 000 cultivated juveniles were collected in a 60 000-m 3 dammed pond at the IMR Austevoll Biological Station (Øiestad et al, 1985).…”

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