Land based on-growing of Atlantic cod (Gadus morhua) using Recirculating Aquaculture Systems; a case study from the Basque region (Northern Spain)

Abstract Glover, K. A., Dahle, G., and Jørstad, K. E. 2011. Genetic identification of farmed and wild Atlantic cod, Gadus morhua, in coastal Norway. – ICES Journal of Marine Science, 68: 901–910. Each year thousands of Atlantic cod escape from Norwegian fish farms. To investigate the potential for the genetic identification of farmed–escaped cod in the wild, three case studies were examined. Samples of farmed, recaptured farmed escapees, and wild cod were screened for ten microsatellite loci and the Pan I locus. Variable genetic differences were observed among cod sampled from different farms and cages (pairwise FST = 0.0–0.1), and in two of the case studies, the most likely farm(s) of origin for most of the recaptured escapees were identified. In case study 2, wild cod were genetically distinct from both farmed fish (pairwise FST = 0.026–0.06) and recaptured farmed–escaped cod (pairwise FST = 0.029 and 0.039), demonstrating the potential to detect genetic interactions in that fjord. Genetic identification of escapees was more challenging in case study 3, and some morphologically characterized wild cod were found to most likely represent farmed escapees. It is concluded that where cod are farmed in the same region as their own parents/grandparents were initially sourced, or where farmed escapees originate from multiple sources, quantifying genetic interactions with wild populations will be challenging with neutral or nearly neutral markers such as microsatellites.

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Intergenerational valuation of fisheries resources can justify long-term conservation: a case study in Atlantic cod (Gadus morhua)

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f05-010 ◽

2005 ◽

Vol 62 (5) ◽

pp. 1104-1110 ◽

Cited By ~ 12

Author(s):

C H Ainsworth ◽

U R Sumaila

Keyword(s):

Discount Rate ◽

Gadus Morhua ◽

Atlantic Cod ◽

Ecosystem Model ◽

Conventional Model ◽

Fisheries Resources ◽

Optimal Harvest ◽

Harvest Policies

Where the conventional model of discounting advocates aggressive harvest policies, intergenerational discounting could have been used to render the historic gross overfishing of Atlantic cod (Gadus morhua) economically unappealing compared with a more conservative long-term strategy. Under these discounting approaches, we compare the historic harvest trend from 1985 (and projected postcollapse earnings) with theoretical optimal harvest profiles determined by an ecosystem model. The optimal scenarios generate less initial harvest than the historic profile but maintain the resource and provide greater yields over the long term. At a discount rate equal to market interest, we demonstrate that it was more economic under conventional valuation to harvest the cod stock to collapse than it would have been to sustain the population. However, under intergenerational valuation, the sustainable optimal scenarios outperform the actual harvest profile. Application of conventional discounting by fishing consortiums may be partly to blame for depletion, yet management fell short of even that ideal.

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