Mating competition between farmed and wild cod Gadus morhua

J E Skjaeraasen; Justin J Meager; Ø Karlsen; I Mayer; G Dahle; G Rudolfsen; A Fernö

doi:10.3354/meps08670

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Mating competition between farmed and wild cod Gadus morhua

Journal article

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Peer reviewed

Mating competition between farmed and wild cod Gadus morhua

J E Skjaeraasen, Justin J Meager, Ø Karlsen, I Mayer, G Dahle, G Rudolfsen and A Fernö

Marine Ecology Progress Series, Vol.412, pp.247-258

2010

DOI: https://doi.org/10.3354/meps08670

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Abstract

Fisheries Sciences

genetic introgression

leks

female choice

sperm traits

Gadus morhua

Increasing numbers of hatchery-produced fish entering marine environments has caused concern over potential fitness depressions in wild populations, yet no study has addressed the likelihood of hybridisation between farmed and wild marine fish. Escape rates of Atlantic cod Gadus morhua L. from commercial net pens have been substantial and there is a risk of interbreeding between depleted local coastal populations and escapees. We studied mating competition between farmed and wild cod in 2 mixed spawning groups. In addition to detailed behavioural analysis, we examined a suite of individual male characteristics thought to be associated with male reproductive success, including, for the first time in any 'naturally' spawning teleost, sperm motility traits. We found that the expression of reproductive behaviours was similar for both male types (farmed and wild). Males 'courted' both sexes, but courtships lasted longer with a female recipient. Both farmed and wild males also directed most female courtships towards farmed females. The frequency of male displays was linked to their steroid levels. Wild males sired 75% of eggs spawned by wild females, but only 48 to 67% of eggs spawned by farmed females. It is likely that wild females rejected farmed males and chose among the wild males based primarily on behavioural cues. Female choice thus appears to be an integral part of the cod mating system. Sperm traits were not associated with overall reproductive success. Our results suggest that hybridisation between farmed escapees and wild cod is likely and that farmed cod may interfere with the natural spawning behaviour of cod.

Details

Title: Mating competition between farmed and wild cod Gadus morhua
Authors: J E Skjaeraasen (Author) - University of Bergen, Norway
Justin J Meager (Author) - University of Bergen, Norway
Ø Karlsen (Author) - Institute of Marine Research, Norway
I Mayer (Author) - University of Bergen, Norway
G Dahle (Author) - Institute of Marine Research, Norway
G Rudolfsen (Author) - University of Tromso, Norway
A Fernö (Author) - University of Bergen
Publication details: Marine Ecology Progress Series, Vol.412, pp.247-258
Publisher: Inter-Research
Date published: 2010
DOI: 10.3354/meps08670
ISSN: 0171-8630
Copyright note: Copyright © 2010 Inter-Research. Reproduced in accordance with the copyright policy of the publisher.
Organisation Unit: University of the Sunshine Coast, Queensland
Language: English
Record Identifier: 99449772602621
Output Type: Journal article

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Collaboration types: Domestic collaboration
Web Of Science research areas: Ecology; Marine & Freshwater Biology; Oceanography

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