Fishery-induced changes to age and length dependent maturation schedules of three demersal fish species in the Firth of Clyde

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24 Citations (Scopus)
1765 Downloads (Pure)


Probabilistic maturation reaction norms (PMRNs) were used to investigate the maturation schedules of cod, haddock and whiting in the Firth Clyde to determine if typical lengths at maturation have changed significantly since 1986. Some potential sources of growth-independent plasticity were accounted for by including sea-surface temperature and abundance variables in the analysis. The PMRNs of the Clyde populations were compared with those from the wider west coast, in conjunction with regional differences in the fishery, to assess whether fishing may have been driving the observed trends of decreasing lengths at maturation. The lengths at which haddock, whiting and female cod were likely to mature decreased significantly during 1986-2009, with rates of change being particularly rapid in the Clyde. It was not possible to estimate PMRNs for male cod due to limited data. Trends in temperature and abundance were shown to have only marginal affects upon PMRN positions, so temporal trends in maturation schedules
appear to have been due to a combination of plastic responses to other environmental variables and/or fishing. Regional differences in fishing intensity and the size-selectivity of the fisheries suggest that the decreases in lengths at maturation have been at least partially due to fishing. The importance and scale of the Clyde Nephrops fishery increased as demersal landings declined, and the majority of demersal fish landings have come from Nephrops bycatch since about 2005 when the demersal fishery ceased. Since it appears as though fishing may have caused increasingly early maturation, and a substantial Nephrops fishery continues to operate in the Clyde, reversal of these changes is likely to take a long time – particularly if there is an evolutionary component to the trends. If size-selective fishing has contributed to the lowered abundance of large fish by encouraging maturation at increasingly small lengths, then large fish may remain uncommon in the Clyde until the observed trends in maturation lengths reverse.
Original languageEnglish
Pages (from-to)14-23
Number of pages10
JournalFisheries Research
Early online date30 May 2015
Publication statusPublished - Oct 2015


  • Firth of Clyde
  • probabilistic maturation reaction norm
  • demersal fish

Research Output

  • 24 Citations
  • 5 Article

Survival of the fittest: explanations for gadoid imbalance in heavily fish seas

Elliott, S. A. M., Allan, B. A., Turrell, W. R., Heath, M. R. & Bailey, D. M., 11 Jun 2018, In : Aquatic Conservation: Marine and Freshwater Ecosystems . 8 p.

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Open Access
2 Citations (Scopus)
5 Downloads (Pure)

Landscape effects on demersal fish revealed by field observations and predictive seabed modelling

Elliott, S. A. M., Sabatino, A. D., Heath, M. R., Turrell, W. R. & Bailey, D. M., 11 Dec 2017, In : PLoS One. 12, 12, 13 p., e0189011.

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Open Access
6 Citations (Scopus)
24 Downloads (Pure)

An assessment of juvenile Atlantic cod distribution and growth using diver operated stereo-video surveys

Elliott, S. A. M., Ahti, P. A., Heath, M. R., Turrell, W. R. & Bailey, D. M., 25 May 2016, In : Journal of Fish Biology. 41 p.

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Open Access
4 Citations (Scopus)
102 Downloads (Pure)


  • 1 Participation in conference
  • 1 Membership of committee

ICES Annual Science Conference 2015

Mike Heath (To be assigned)

22 Sep 2015

Activity: Participating in or organising an event typesParticipation in conference

Scottish Government (External organisation)

Mike Heath (Member)

Jun 2015 → …

Activity: Membership typesMembership of committee

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