The importance of coastal environments for the resilience of gadoid fish populations

The importance of coastal environments for the resilience of gadoid fish populations

Issued: Wed, 22 Oct 2014 22:10:00 BST

Elliott, Bailey

In recent years important gadoid stocks have been reduced and unlike some stocks in the North Sea which have been better studied (i.e. cod, Gadus morhua), stocks of commercial importance on the west coast of Scotland are expected to remain below maximum sustainable yield (Bailey et al. 2011; Ware, 2009; Drinkwater, 2005, ICES, 2013).

Of particular concern is the priority marine feature listed Atlantic cod, which has been listed by ICES as below ‘safe biological limits’ and by OSPAR as ‘threatened and/or declining’ (ICES, 2013, OSPAR, 2008, Fernandes & Cook, 2013). The full causes of declining stocks are unclear, however anthropogenic impacts from fishing activities (decline in stock and habitat modification) and the effects of climate change are of concern (Frost et al. 2012; Heath et al. 2012; Pinnegar et al. 2010).

Several studies have taken place looking at spawning areas for gadoids (e.g. Galley et al., 2006; Wright et al., 2006, etc) and looking at juvenile abundances more generically using trawl methods (Ware 2009; Demain et al., 2011; Wright et al., 2010). However detailed research into gadoid habitat association is minimal, particularly on the west coast of Scotland. Essential fish habitat is poorly defined for early stages of most commercial species, particularly since juvenile finfish occupy a narrower range of habitat than adults (Ryer et al., 2007) and given cohort size of marine fish is thought to be determined during the first year of piscine life (Ings et al., 2008).

To better understand the reasons for an unrecovered gadoid stock on the west coast of Scotland, research into the role of juvenile gadoid habitats for stock recruitment and their vulnerability to anthropogenic activities could help understand how to improve the recovery of gadoid stocks on the west coast of Scotland and better manage impacts from climate change and benthic fishing activities.

This project is studying the role of coastal subtidal habitats in the Firth of Clyde, on the west coast of Scotland for juvenile gadoids. Gadoids of commercial importance such as Atlantic cod, whiting (Merlangius merlangus) and haddock (Melanogrammus aeglefinus) will be the focus of research. Stereo-Baited Remote Underwater Video drops and Stereo SCUBA transects have been used to investigate the relationship of these juvenile gadoid species to substrate types.

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